Recent Publications

@article{RN83,
   author = {Duncan, J. L. and Ahmad, R. N. and Danesi, H. and Slade, D. J. and Davalos, R. V. and Verbridge, S. S.},
   title = {Electro-antibacterial therapy (EAT) to enhance intracellular bacteria clearance in pancreatic cancer cells},
   journal = {Bioelectrochemistry},
   volume = {157},
   pages = {108669},
   note = {1878-562x
Duncan, Josie L
Ahmad, Raffae N
Danesi, Hunter
Slade, Daniel J
Davalos, Rafael V
Verbridge, Scott S
Journal Article
Netherlands
2024/02/21
Bioelectrochemistry. 2024 Feb 15;157:108669. doi: 10.1016/j.bioelechem.2024.108669.},
   abstract = {Intratumoral bacteria have been implicated in driving tumor progression, yet effective treatments to modulate the tumor microbiome remain limited. In this study, we investigate the use of electroporation in combination with metronidazole to enhance the clearance of intracellular Fusobacterium nucleatum within pancreatic cancer cells. We explore various parameters, including electric field strength, pulse width, and pulse number to assess the permeability of pancreatic cancer cells infected with F. nucleatum, compared to non-infected cells of the same type. We subsequently quantify the clearance of intracellular bacteria when these pulsing schemes are applied to a suspension of infected pancreatic cancer cells in the presence of metronidazole. Our results reveal distinct differences in cell permeability between infected and non-infected cells, identifying a unique biophysical marker for host cells infected with F. nucleatum. We demonstrate that the combinatorial use of electroporation and metronidazole significantly enhances the delivery of metronidazole into host cells, leading to more effective clearance of intracellular F. nucleatum compared to independent treatments; we term this novel approach Electro-Antibacterial Therapy (EAT). EAT holds promise as an innovative strategy for addressing intratumoral bacteria in pancreatic cancer, other malignancies, and potentially treatment-resistant infections, offering new avenues for therapeutic intervention.},
   keywords = {Antibiotic
Bacteria
Electroporation
Fusobacterium
Pulsed Electric Fields
Tumor Microbiome},
   ISSN = {1567-5394},
   DOI = {10.1016/j.bioelechem.2024.108669},
   year = {2024},
   type = {Journal Article}
}

Intratumoral bacteria have been implicated in driving tumor progression, yet effective treatments to modulate the tumor microbiome remain limited. In this study, we investigate the use of electroporation in combination with metronidazole to enhance the clearance of intracellular Fusobacterium nucleatum within pancreatic cancer cells. We explore various parameters, including electric field strength, pulse width, and pulse number to assess the permeability of pancreatic cancer cells infected with F. nucleatum, compared to non-infected cells of the same type. We subsequently quantify the clearance of intracellular bacteria when these pulsing schemes are applied to a suspension of infected pancreatic cancer cells in the presence of metronidazole. Our results reveal distinct differences in cell permeability between infected and non-infected cells, identifying a unique biophysical marker for host cells infected with F. nucleatum. We demonstrate that the combinatorial use of electroporation and metronidazole significantly enhances the delivery of metronidazole into host cells, leading to more effective clearance of intracellular F. nucleatum compared to independent treatments; we term this novel approach Electro-Antibacterial Therapy (EAT). EAT holds promise as an innovative strategy for addressing intratumoral bacteria in pancreatic cancer, other malignancies, and potentially treatment-resistant infections, offering new avenues for therapeutic intervention.

@article{RN86,
   author = {Jacobs, E. J. th and Aycock, K. N. and Santos, P. P. and Tuohy, J. L. and Davalos, R. V.},
   title = {Rapid estimation of electroporation-dependent tissue properties in canine lung tumors using a deep neural network},
   journal = {Biosens Bioelectron},
   volume = {244},
   pages = {115777},
   note = {1873-4235
Jacobs, Edward J 4th
Aycock, Kenneth N
Santos, Pedro P
Tuohy, Joanne L
Davalos, Rafael V
Journal Article
England
2023/11/05
Biosens Bioelectron. 2024 Jan 15;244:115777. doi: 10.1016/j.bios.2023.115777. Epub 2023 Oct 21.},
   abstract = {The efficiency of electroporation treatments depends on the application of a critical electric field over the targeted tissue volume. Both the electric field and temperature distribution strongly depend on the tissue-specific electrical properties, which both differ between patients in healthy and malignant tissues and change in an electric field-dependent manner from the electroporation process itself. Therefore, tissue property estimations are paramount for treatment planning with electroporation therapies. Ex vivo methods to find electrical tissue properties often misrepresent the targeted tissue, especially when translating results to tumors. A voltage ramp is an in situ method that applies a series of increasing electric potentials across treatment electrodes and measures the resulting current. Here, we develop a robust deep neural network, trained on finite element model simulations, to directly predict tissue properties from a measured voltage ramp. There was minimal test error (R(2)>0.94;p<0.0001) in three important electric tissue properties. Further, our model was validated to correctly predict the complete dynamic conductivity curve in a previously characterized ex vivo liver model (R(2)>0.93;p<0.0001) within 100 s from probe insertion, showing great utility for a clinical application. Lastly, we characterize the first reported electrical tissue properties of lung tumors from five canine patients (R(2)>0.99;p<0.0001). We believe this platform can be incorporated prior to treatment to quickly ascertain patient-specific tissue properties required for electroporation treatment planning models or real-time treatment prediction algorithms. Further, this method can be used over traditional ex vivo methods for in situ tissue characterization with clinically relevant geometries.},
   keywords = {Humans
Animals
Dogs
*Biosensing Techniques
Electroporation
Electroporation Therapies
Electric Conductivity
Neural Networks, Computer
*Lung Neoplasms
Artificial intelligence
Cancer
Deep neural network
Electric tissue properties
Finite element methods
Pulsed field ablation
Tissue ablation},
   ISSN = {0956-5663},
   DOI = {10.1016/j.bios.2023.115777},
   year = {2024},
   type = {Journal Article}
}

The efficiency of electroporation treatments depends on the application of a critical electric field over the targeted tissue volume. Both the electric field and temperature distribution strongly depend on the tissue-specific electrical properties, which both differ between patients in healthy and malignant tissues and change in an electric field-dependent manner from the electroporation process itself. Therefore, tissue property estimations are paramount for treatment planning with electroporation therapies. Ex vivo methods to find electrical tissue properties often misrepresent the targeted tissue, especially when translating results to tumors. A voltage ramp is an in situ method that applies a series of increasing electric potentials across treatment electrodes and measures the resulting current. Here, we develop a robust deep neural network, trained on finite element model simulations, to directly predict tissue properties from a measured voltage ramp. There was minimal test error (R(2)>0.94;p<0.0001) in three important electric tissue properties. Further, our model was validated to correctly predict the complete dynamic conductivity curve in a previously characterized ex vivo liver model (R(2)>0.93;p<0.0001) within 100 s from probe insertion, showing great utility for a clinical application. Lastly, we characterize the first reported electrical tissue properties of lung tumors from five canine patients (R(2)>0.99;p<0.0001). We believe this platform can be incorporated prior to treatment to quickly ascertain patient-specific tissue properties required for electroporation treatment planning models or real-time treatment prediction algorithms. Further, this method can be used over traditional ex vivo methods for in situ tissue characterization with clinically relevant geometries.

@article{RN87,
   author = {Jacobs Iv, E. J. and Campelo, S. N. and Charlton, A. and Altreuter, S. and Davalos, R. V.},
   title = {Characterizing reversible, irreversible, and calcium electroporation to generate a burst-dependent dynamic conductivity curve},
   journal = {Bioelectrochemistry},
   volume = {155},
   pages = {108580},
   note = {1878-562x
Jacobs Iv, Edward J
Campelo, Sabrina N
Charlton, Alyssa
Altreuter, Sara
Davalos, Rafael V
Journal Article
Netherlands
2023/10/03
Bioelectrochemistry. 2024 Feb;155:108580. doi: 10.1016/j.bioelechem.2023.108580. Epub 2023 Sep 25.},
   abstract = {The relationships between burst number, reversible, irreversible, and calcium electroporation have not been comprehensively evaluated in tumor tissue-mimics. Our findings indicate that electroporation effects saturate with a rate constant (τ) of 20 bursts for both conventional and high frequency waveforms (R(2) > 0.88), with the separation between reversible and irreversible electroporation thresholds converging at 50 bursts. We find the lethal thresholds for calcium electroporation are statistically similar to reversible electroporation (R(2) > 0.99). We then develop a burst-dependent dynamic conductivity curve that now incorporates electroporation effects due to both the electric field magnitude and burst number. Simulated ablation and thermal damage volumes vary significantly between finite element models using either the conventional or new burst-dependent dynamic conductivity curve (p < 0.05). Lastly, for clinically relevant protocols, thermal damage is indicated to not begin until 50 bursts, with maximum nonthermal ablation volumes at 100 bursts (1.5-13% thermal damage by volume). We find that >100 bursts generated negligible increases in ablation volumes with 40-70% thermal damage by volume at 300 bursts. Our results illustrate the need for considering burst number in minimizing thermal damage, choosing adjuvant therapies, and in modeling electroporation effects at low burst numbers.},
   keywords = {*Calcium
*Electroporation/methods
Electric Conductivity
Electroporation Therapies
Electricity
Burst number
Calcium electroporation
Dynamic conductivity curve
Electroporation
Pulsed field ablation
Thermal damage},
   ISSN = {1567-5394},
   DOI = {10.1016/j.bioelechem.2023.108580},
   year = {2024},
   type = {Journal Article}
}

The relationships between burst number, reversible, irreversible, and calcium electroporation have not been comprehensively evaluated in tumor tissue-mimics. Our findings indicate that electroporation effects saturate with a rate constant (τ) of 20 bursts for both conventional and high frequency waveforms (R(2) > 0.88), with the separation between reversible and irreversible electroporation thresholds converging at 50 bursts. We find the lethal thresholds for calcium electroporation are statistically similar to reversible electroporation (R(2) > 0.99). We then develop a burst-dependent dynamic conductivity curve that now incorporates electroporation effects due to both the electric field magnitude and burst number. Simulated ablation and thermal damage volumes vary significantly between finite element models using either the conventional or new burst-dependent dynamic conductivity curve (p < 0.05). Lastly, for clinically relevant protocols, thermal damage is indicated to not begin until 50 bursts, with maximum nonthermal ablation volumes at 100 bursts (1.5-13% thermal damage by volume). We find that >100 bursts generated negligible increases in ablation volumes with 40-70% thermal damage by volume at 300 bursts. Our results illustrate the need for considering burst number in minimizing thermal damage, choosing adjuvant therapies, and in modeling electroporation effects at low burst numbers.

@article{RN84,
   author = {Salameh, Z. S. and Aycock, K. N. and Alinezhadbalalami, N. and Imran, K. M. and McKillop, I. H. and Allen, I. C. and Davalos, R. V.},
   title = {Correction: Harnessing the Electrochemical Effects of Electroporation-Based Therapies to Enhance Anti-tumor Immune Responses},
   journal = {Ann Biomed Eng},
   note = {1573-9686
Salameh, Zaid S
Aycock, Kenneth N
Alinezhadbalalami, Nastaran
Imran, Khan Mohammad
McKillop, Iain H
Allen, Irving C
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Published Erratum
United States
2024/01/11
Ann Biomed Eng. 2024 Jan 10. doi: 10.1007/s10439-024-03444-w.},
   ISSN = {0090-6964},
   DOI = {10.1007/s10439-024-03444-w},
   year = {2024},
   type = {Journal Article}
}

@article{RN85,
   author = {Salameh, Z. S. and Aycock, K. N. and Alinezhadbalalami, N. and Imran, K. M. and McKillop, I. H. and Allen, I. C. and Davalos, R. V.},
   title = {Harnessing the Electrochemical Effects of Electroporation-Based Therapies to Enhance Anti-tumor Immune Responses},
   journal = {Ann Biomed Eng},
   volume = {52},
   number = {1},
   pages = {48-56},
   note = {1573-9686
Salameh, Zaid S
Aycock, Kenneth N
Alinezhadbalalami, Nastaran
Imran, Khan Mohammad
McKillop, Iain H
Allen, Irving C
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
R01 CA274439/CA/NCI NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
United States
2023/11/22
Ann Biomed Eng. 2024 Jan;52(1):48-56. doi: 10.1007/s10439-023-03403-x. Epub 2023 Nov 21.},
   abstract = {This study introduces a new method of targeting acidosis (low pH) within the tumor microenvironment (TME) through the use of cathodic electrochemical reactions (CER). Low pH is oncogenic by supporting immunosuppression. Electrochemical reactions create local pH effects when a current passes through an electrolytic substrate such as biological tissue. Electrolysis has been used with electroporation (destabilization of the lipid bilayer via an applied electric potential) to increase cell death areas. However, the regulated increase of pH through only the cathode electrode has been ignored as a possible method to alleviate TME acidosis, which could provide substantial immunotherapeutic benefits. Here, we show through ex vivo modeling that CERs can intentionally elevate pH to an anti-tumor level and that increased alkalinity promotes activation of naïve macrophages. This study shows the potential of CERs to improve acidity within the TME and that it has the potential to be paired with existing electric field-based cancer therapies or as a stand-alone therapy.},
   keywords = {Humans
*Neoplasms/therapy
Electroporation/methods
Electricity
Immunity
*Acidosis
Tumor Microenvironment
Ablation
Anti-tumor
Direct current
Electrochemical
Electroporation
Hepatocellular carcinoma
Immunology
Immunosuppressive
Irreversible electroporation
Thp-1
Tumor-associated macrophages
Warburg effect
pH},
   ISSN = {0090-6964 (Print)
0090-6964},
   DOI = {10.1007/s10439-023-03403-x},
   year = {2024},
   type = {Journal Article}
}

This study introduces a new method of targeting acidosis (low pH) within the tumor microenvironment (TME) through the use of cathodic electrochemical reactions (CER). Low pH is oncogenic by supporting immunosuppression. Electrochemical reactions create local pH effects when a current passes through an electrolytic substrate such as biological tissue. Electrolysis has been used with electroporation (destabilization of the lipid bilayer via an applied electric potential) to increase cell death areas. However, the regulated increase of pH through only the cathode electrode has been ignored as a possible method to alleviate TME acidosis, which could provide substantial immunotherapeutic benefits. Here, we show through ex vivo modeling that CERs can intentionally elevate pH to an anti-tumor level and that increased alkalinity promotes activation of naïve macrophages. This study shows the potential of CERs to improve acidity within the TME and that it has the potential to be paired with existing electric field-based cancer therapies or as a stand-alone therapy.

@article{RN90,
   author = {Adams, W. P. and Raisch, T. B. and Zhao, Y. and Davalos, R. and Barrett, S. and King, D. R. and Bain, C. B. and Colucci-Chang, K. and Blair, G. A. and Hanlon, A. and Lozano, A. and Veeraraghavan, R. and Wan, X. and Deschenes, I. and Smyth, J. W. and Hoeker, G. S. and Gourdie, R. G. and Poelzing, S.},
   title = {Extracellular Perinexal Separation Is a Principal Determinant of Cardiac Conduction},
   journal = {Circ Res},
   volume = {133},
   number = {8},
   pages = {658-673},
   note = {1524-4571
Adams, William P
Orcid: 0000-0002-5601-663x
Raisch, Tristan B
Orcid: 0000-0002-6469-8570
Zhao, Yajun
Orcid: 0000-0003-3029-0291
Davalos, Rafael
Orcid: 0000-0003-1503-9509
Barrett, Sarah
King, D Ryan
Bain, Chandra B
Orcid: 0000-0002-5308-5509
Colucci-Chang, Katrina
Blair, Grace A
Orcid: 0000-0002-5633-5497
Hanlon, Alexandra
Lozano, Alicia
Veeraraghavan, Rengasayee
Wan, Xiaoping
Orcid: 0009-0006-0417-3437
Deschenes, Isabelle
Smyth, James W
Hoeker, Gregory S
Orcid: 0000-0002-3917-4791
Gourdie, Robert G
Orcid: 0000-0001-6021-0796
Poelzing, Steven
Orcid: 0000-0002-6979-1264
R01 HL094450/HL/NHLBI NIH HHS/United States
R01 HL159097/HL/NHLBI NIH HHS/United States
R01 HL132236/HL/NHLBI NIH HHS/United States
R01 HL096962/HL/NHLBI NIH HHS/United States
R35 HL161237/HL/NHLBI NIH HHS/United States
R01 HL102298/HL/NHLBI NIH HHS/United States
F31 HL140873/HL/NHLBI NIH HHS/United States
R01 HL056728/HL/NHLBI NIH HHS/United States
R01 HL138003/HL/NHLBI NIH HHS/United States
R25 GM072767/GM/NIGMS NIH HHS/United States
F31 HL147438/HL/NHLBI NIH HHS/United States
R01 HL141855/HL/NHLBI NIH HHS/United States
Journal Article
United States
2023/09/08
Circ Res. 2023 Sep 29;133(8):658-673. doi: 10.1161/CIRCRESAHA.123.322567. Epub 2023 Sep 8.},
   abstract = {BACKGROUND: Cardiac conduction is understood to occur through gap junctions. Recent evidence supports ephaptic coupling as another mechanism of electrical communication in the heart. Conduction via gap junctions predicts a direct relationship between conduction velocity (CV) and bulk extracellular resistance. By contrast, ephaptic theory is premised on the existence of a biphasic relationship between CV and the volume of specialized extracellular clefts within intercalated discs such as the perinexus. Our objective was to determine the relationship between ventricular CV and structural changes to micro- and nanoscale extracellular spaces. METHODS: Conduction and Cx43 (connexin43) protein expression were quantified from optically mapped guinea pig whole-heart preparations perfused with the osmotic agents albumin, mannitol, dextran 70 kDa, or dextran 2 MDa. Peak sodium current was quantified in isolated guinea pig ventricular myocytes. Extracellular resistance was quantified by impedance spectroscopy. Intercellular communication was assessed in a heterologous expression system with fluorescence recovery after photobleaching. Perinexal width was quantified from transmission electron micrographs. RESULTS: CV primarily in the transverse direction of propagation was significantly reduced by mannitol and increased by albumin and both dextrans. The combination of albumin and dextran 70 kDa decreased CV relative to albumin alone. Extracellular resistance was reduced by mannitol, unchanged by albumin, and increased by both dextrans. Cx43 expression and conductance and peak sodium currents were not significantly altered by the osmotic agents. In response to osmotic agents, perinexal width, in order of narrowest to widest, was albumin with dextran 70 kDa; albumin or dextran 2 MDa; dextran 70 kDa or no osmotic agent, and mannitol. When compared in the same order, CV was biphasically related to perinexal width. CONCLUSIONS: Cardiac conduction does not correlate with extracellular resistance but is biphasically related to perinexal separation, providing evidence that the relationship between CV and extracellular volume is determined by ephaptic mechanisms under conditions of normal gap junctional coupling.},
   keywords = {Animals
Guinea Pigs
*Dextrans/metabolism
*Connexin 43/metabolism
Myocytes, Cardiac/metabolism
Sodium/metabolism
Gap Junctions/metabolism
Albumins/metabolism
Mannitol/pharmacology/metabolism
Action Potentials
electrical conductivity
electrophysiology
gap junctions
heart conduction system
osmotic stress},
   ISSN = {0009-7330 (Print)
0009-7330},
   DOI = {10.1161/circresaha.123.322567},
   year = {2023},
   type = {Journal Article}
}

BACKGROUND: Cardiac conduction is understood to occur through gap junctions. Recent evidence supports ephaptic coupling as another mechanism of electrical communication in the heart. Conduction via gap junctions predicts a direct relationship between conduction velocity (CV) and bulk extracellular resistance. By contrast, ephaptic theory is premised on the existence of a biphasic relationship between CV and the volume of specialized extracellular clefts within intercalated discs such as the perinexus. Our objective was to determine the relationship between ventricular CV and structural changes to micro- and nanoscale extracellular spaces. METHODS: Conduction and Cx43 (connexin43) protein expression were quantified from optically mapped guinea pig whole-heart preparations perfused with the osmotic agents albumin, mannitol, dextran 70 kDa, or dextran 2 MDa. Peak sodium current was quantified in isolated guinea pig ventricular myocytes. Extracellular resistance was quantified by impedance spectroscopy. Intercellular communication was assessed in a heterologous expression system with fluorescence recovery after photobleaching. Perinexal width was quantified from transmission electron micrographs. RESULTS: CV primarily in the transverse direction of propagation was significantly reduced by mannitol and increased by albumin and both dextrans. The combination of albumin and dextran 70 kDa decreased CV relative to albumin alone. Extracellular resistance was reduced by mannitol, unchanged by albumin, and increased by both dextrans. Cx43 expression and conductance and peak sodium currents were not significantly altered by the osmotic agents. In response to osmotic agents, perinexal width, in order of narrowest to widest, was albumin with dextran 70 kDa; albumin or dextran 2 MDa; dextran 70 kDa or no osmotic agent, and mannitol. When compared in the same order, CV was biphasically related to perinexal width. CONCLUSIONS: Cardiac conduction does not correlate with extracellular resistance but is biphasically related to perinexal separation, providing evidence that the relationship between CV and extracellular volume is determined by ephaptic mechanisms under conditions of normal gap junctional coupling.

@article{RN92,
   author = {Campana, L. G. and Daud, A. and Lancellotti, F. and Arroyo, J. P. and Davalos, R. V. and Di Prata, C. and Gehl, J.},
   title = {Pulsed Electric Fields in Oncology: A Snapshot of Current Clinical Practices and Research Directions from the 4th World Congress of Electroporation},
   journal = {Cancers (Basel)},
   volume = {15},
   number = {13},
   note = {2072-6694
Campana, Luca G
Orcid: 0000-0002-8466-8459
Daud, Adil
Lancellotti, Francesco
Orcid: 0000-0002-1830-127x
Arroyo, Julio P
Orcid: 0000-0003-4690-6337
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Di Prata, Claudia
Gehl, Julie
Orcid: 0000-0003-3829-0210
R25 GM072767/GM/NIGMS NIH HHS/United States
Journal Article
Review
Switzerland
2023/07/14
Cancers (Basel). 2023 Jun 25;15(13):3340. doi: 10.3390/cancers15133340.},
   abstract = {The 4th World Congress of Electroporation (Copenhagen, 9-13 October 2022) provided a unique opportunity to convene leading experts in pulsed electric fields (PEF). PEF-based therapies harness electric fields to produce therapeutically useful effects on cancers and represent a valuable option for a variety of patients. As such, irreversible electroporation (IRE), gene electrotransfer (GET), electrochemotherapy (ECT), calcium electroporation (Ca-EP), and tumour-treating fields (TTF) are on the rise. Still, their full therapeutic potential remains underappreciated, and the field faces fragmentation, as shown by parallel maturation and differences in the stages of development and regulatory approval worldwide. This narrative review provides a glimpse of PEF-based techniques, including key mechanisms, clinical indications, and advances in therapy; finally, it offers insights into current research directions. By highlighting a common ground, the authors aim to break silos, strengthen cross-functional collaboration, and pave the way to novel possibilities for intervention. Intriguingly, beyond their peculiar mechanism of action, PEF-based therapies share technical interconnections and multifaceted biological effects (e.g., vascular, immunological) worth exploiting in combinatorial strategies.},
   keywords = {cancer
electrochemotherapy
electroporation
gene electrotransfer
irreversible electroporation
quality of life
tumour-treating fields},
   ISSN = {2072-6694 (Print)
2072-6694},
   DOI = {10.3390/cancers15133340},
   year = {2023},
   type = {Journal Article}
}

The 4th World Congress of Electroporation (Copenhagen, 9-13 October 2022) provided a unique opportunity to convene leading experts in pulsed electric fields (PEF). PEF-based therapies harness electric fields to produce therapeutically useful effects on cancers and represent a valuable option for a variety of patients. As such, irreversible electroporation (IRE), gene electrotransfer (GET), electrochemotherapy (ECT), calcium electroporation (Ca-EP), and tumour-treating fields (TTF) are on the rise. Still, their full therapeutic potential remains underappreciated, and the field faces fragmentation, as shown by parallel maturation and differences in the stages of development and regulatory approval worldwide. This narrative review provides a glimpse of PEF-based techniques, including key mechanisms, clinical indications, and advances in therapy; finally, it offers insights into current research directions. By highlighting a common ground, the authors aim to break silos, strengthen cross-functional collaboration, and pave the way to novel possibilities for intervention. Intriguingly, beyond their peculiar mechanism of action, PEF-based therapies share technical interconnections and multifaceted biological effects (e.g., vascular, immunological) worth exploiting in combinatorial strategies.

@article{RN97,
   author = {Campelo, S. N. and Huang, P. H. and Buie, C. R. and Davalos, R. V.},
   title = {Recent Advancements in Electroporation Technologies: From Bench to Clinic},
   journal = {Annu Rev Biomed Eng},
   volume = {25},
   pages = {77-100},
   note = {1545-4274
Campelo, Sabrina N
Huang, Po-Hsun
Buie, Cullen R
Davalos, Rafael V
P01 CA207206/CA/NCI NIH HHS/United States
RM1 GM135102/GM/NIGMS NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Review
United States
2023/03/01
Annu Rev Biomed Eng. 2023 Jun 8;25:77-100. doi: 10.1146/annurev-bioeng-110220-023800. Epub 2023 Feb 28.},
   abstract = {Over the past decade, the increased adoption of electroporation-based technologies has led to an expansion of clinical research initiatives. Electroporation has been utilized in molecular biology for mammalian and bacterial transfection; for food sanitation; and in therapeutic settings to increase drug uptake, for gene therapy, and to eliminate cancerous tissues. We begin this article by discussing the biophysics required for understanding the concepts behind the cell permeation phenomenon that is electroporation. We then review nano- and microscale single-cell electroporation technologies before scaling up to emerging in vivo applications.},
   keywords = {Animals
Humans
Electroporation
Transfection
*Neoplasms/therapy
Electroporation Therapies
Genetic Therapy
*Electrochemotherapy
Mammals
electrochemotherapy
gene therapy
microfluidics
pulsed field ablation},
   ISSN = {1523-9829},
   DOI = {10.1146/annurev-bioeng-110220-023800},
   year = {2023},
   type = {Journal Article}
}

Over the past decade, the increased adoption of electroporation-based technologies has led to an expansion of clinical research initiatives. Electroporation has been utilized in molecular biology for mammalian and bacterial transfection; for food sanitation; and in therapeutic settings to increase drug uptake, for gene therapy, and to eliminate cancerous tissues. We begin this article by discussing the biophysics required for understanding the concepts behind the cell permeation phenomenon that is electroporation. We then review nano- and microscale single-cell electroporation technologies before scaling up to emerging in vivo applications.

@article{RN94,
   author = {Campelo, S. N. and Lorenzo, M. F. and Partridge, B. and Alinezhadbalalami, N. and Kani, Y. and Garcia, J. and Saunier, S. and Thomas, S. C. and Hinckley, J. and Verbridge, S. S. and Davalos, R. V. and Rossmeisl, J. H., Jr.},
   title = {High-frequency irreversible electroporation improves survival and immune cell infiltration in rodents with malignant gliomas},
   journal = {Front Oncol},
   volume = {13},
   pages = {1171278},
   note = {2234-943x
Campelo, Sabrina N
Lorenzo, Melvin F
Partridge, Brittanie
Alinezhadbalalami, Nastaran
Kani, Yukitaka
Garcia, Josefa
Saunier, Sofie
Thomas, Sean C
Hinckley, Jonathan
Verbridge, Scott S
Davalos, Rafael V
Rossmeisl, John H Jr
P01 CA207206/CA/NCI NIH HHS/United States
Journal Article
Switzerland
2023/05/22
Front Oncol. 2023 May 5;13:1171278. doi: 10.3389/fonc.2023.1171278. eCollection 2023.},
   abstract = {BACKGROUND: Irreversible electroporation (IRE) has been previously investigated in preclinical trials as a treatment for intracranial malignancies. Here, we investigate next generation high-frequency irreversible electroporation (H-FIRE), as both a monotherapy and a combinatorial therapy, for the treatment of malignant gliomas. METHODS: Hydrogel tissue scaffolds and numerical modeling were used to inform in-vivo H-FIRE pulsing parameters for our orthotopic tumor-bearing glioma model. Fischer rats were separated into five treatment cohorts including high-dose H-FIRE (1750V/cm), low-dose H-FIRE (600V/cm), combinatorial high-dose H-FIRE + liposomal doxorubicin, low-dose H-FIRE + liposomal doxorubicin, and standalone liposomal doxorubicin groups. Cohorts were compared against a standalone tumor-bearing sham group which received no therapeutic intervention. To further enhance the translational value of our work, we characterize the local and systemic immune responses to intracranial H-FIRE at the study timepoint. RESULTS: The median survival for each cohort are as follows: 31 days (high-dose H-FIRE), 38 days (low-dose H-FIRE), 37.5 days (high-dose H-FIRE + liposomal doxorubicin), 27 days (low-dose H-FIRE + liposomal doxorubicin), 20 days (liposomal doxorubicin), and 26 days (sham). A statistically greater overall survival fraction was noted in the high-dose H-FIRE + liposomal doxorubicin (50%, p = 0.044), high-dose H-FIRE (28.6%, p = 0.034), and the low-dose H-FIRE (20%, p = 0.0214) compared to the sham control (0%). Compared to sham controls, brain sections of rats treated with H-FIRE demonstrated significant increases in IHC scores for CD3+ T-cells (p = 0.0014), CD79a+ B-cells (p = 0.01), IBA-1+ dendritic cells/microglia (p = 0.04), CD8+ cytotoxic T-cells (p = 0.0004), and CD86+ M1 macrophages (p = 0.01). CONCLUSIONS: H-FIRE may be used as both a monotherapy and a combinatorial therapy to improve survival in the treatment of malignant gliomas while also promoting the presence of infiltrative immune cells.},
   keywords = {blood-brain barrier disruption
electroporation
glioblastoma
immune response
intracranial
numerical modeling
pulsed electric field (PEF)},
   ISSN = {2234-943X (Print)
2234-943x},
   DOI = {10.3389/fonc.2023.1171278},
   year = {2023},
   type = {Journal Article}
}

BACKGROUND: Irreversible electroporation (IRE) has been previously investigated in preclinical trials as a treatment for intracranial malignancies. Here, we investigate next generation high-frequency irreversible electroporation (H-FIRE), as both a monotherapy and a combinatorial therapy, for the treatment of malignant gliomas. METHODS: Hydrogel tissue scaffolds and numerical modeling were used to inform in-vivo H-FIRE pulsing parameters for our orthotopic tumor-bearing glioma model. Fischer rats were separated into five treatment cohorts including high-dose H-FIRE (1750V/cm), low-dose H-FIRE (600V/cm), combinatorial high-dose H-FIRE + liposomal doxorubicin, low-dose H-FIRE + liposomal doxorubicin, and standalone liposomal doxorubicin groups. Cohorts were compared against a standalone tumor-bearing sham group which received no therapeutic intervention. To further enhance the translational value of our work, we characterize the local and systemic immune responses to intracranial H-FIRE at the study timepoint. RESULTS: The median survival for each cohort are as follows: 31 days (high-dose H-FIRE), 38 days (low-dose H-FIRE), 37.5 days (high-dose H-FIRE + liposomal doxorubicin), 27 days (low-dose H-FIRE + liposomal doxorubicin), 20 days (liposomal doxorubicin), and 26 days (sham). A statistically greater overall survival fraction was noted in the high-dose H-FIRE + liposomal doxorubicin (50%, p = 0.044), high-dose H-FIRE (28.6%, p = 0.034), and the low-dose H-FIRE (20%, p = 0.0214) compared to the sham control (0%). Compared to sham controls, brain sections of rats treated with H-FIRE demonstrated significant increases in IHC scores for CD3+ T-cells (p = 0.0014), CD79a+ B-cells (p = 0.01), IBA-1+ dendritic cells/microglia (p = 0.04), CD8+ cytotoxic T-cells (p = 0.0004), and CD86+ M1 macrophages (p = 0.01). CONCLUSIONS: H-FIRE may be used as both a monotherapy and a combinatorial therapy to improve survival in the treatment of malignant gliomas while also promoting the presence of infiltrative immune cells.

@article{RN89,
   author = {Duncan, J. L. and Bloomfield, M. and Swami, N. and Cimini, D. and Davalos, R. V.},
   title = {High-Frequency Dielectrophoresis Reveals That Distinct Bio-Electric Signatures of Colorectal Cancer Cells Depend on Ploidy and Nuclear Volume},
   journal = {Micromachines (Basel)},
   volume = {14},
   number = {9},
   note = {2072-666x
Duncan, Josie L
Orcid: 0000-0002-4743-1540
Bloomfield, Mathew
Orcid: 0000-0002-1782-081x
Swami, Nathan
Orcid: 0000-0002-0492-1160
Cimini, Daniela
Orcid: 0000-0002-4082-4894
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
F31 CA271763/CA/NCI NIH HHS/United States
R01 GM140042/GM/NIGMS NIH HHS/United States
Journal Article
Switzerland
2023/09/28
Micromachines (Basel). 2023 Sep 1;14(9):1723. doi: 10.3390/mi14091723.},
   abstract = {Aneuploidy, or an incorrect chromosome number, is ubiquitous among cancers. Whole-genome duplication, resulting in tetraploidy, often occurs during the evolution of aneuploid tumors. Cancers that evolve through a tetraploid intermediate tend to be highly aneuploid and are associated with poor patient prognosis. The identification and enrichment of tetraploid cells from mixed populations is necessary to understand the role these cells play in cancer progression. Dielectrophoresis (DEP), a label-free electrokinetic technique, can distinguish cells based on their intracellular properties when stimulated above 10 MHz, but DEP has not been shown to distinguish tetraploid and/or aneuploid cancer cells from mixed tumor cell populations. Here, we used high-frequency DEP to distinguish cell subpopulations that differ in ploidy and nuclear size under flow conditions. We used impedance analysis to quantify the level of voltage decay at high frequencies and its impact on the DEP force acting on the cell. High-frequency DEP distinguished diploid cells from tetraploid clones due to their size and intracellular composition at frequencies above 40 MHz. Our findings demonstrate that high-frequency DEP can be a useful tool for identifying and distinguishing subpopulations with nuclear differences to determine their roles in disease progression.},
   keywords = {aneuploidy
electrokinetics
microfluidics},
   ISSN = {2072-666X (Print)
2072-666x},
   DOI = {10.3390/mi14091723},
   year = {2023},
   type = {Journal Article}
}

Aneuploidy, or an incorrect chromosome number, is ubiquitous among cancers. Whole-genome duplication, resulting in tetraploidy, often occurs during the evolution of aneuploid tumors. Cancers that evolve through a tetraploid intermediate tend to be highly aneuploid and are associated with poor patient prognosis. The identification and enrichment of tetraploid cells from mixed populations is necessary to understand the role these cells play in cancer progression. Dielectrophoresis (DEP), a label-free electrokinetic technique, can distinguish cells based on their intracellular properties when stimulated above 10 MHz, but DEP has not been shown to distinguish tetraploid and/or aneuploid cancer cells from mixed tumor cell populations. Here, we used high-frequency DEP to distinguish cell subpopulations that differ in ploidy and nuclear size under flow conditions. We used impedance analysis to quantify the level of voltage decay at high frequencies and its impact on the DEP force acting on the cell. High-frequency DEP distinguished diploid cells from tetraploid clones due to their size and intracellular composition at frequencies above 40 MHz. Our findings demonstrate that high-frequency DEP can be a useful tool for identifying and distinguishing subpopulations with nuclear differences to determine their roles in disease progression.

@article{RN98,
   author = {Duncan, J. L. and Schultz, J. and Barlow, Z. and Davalos, R. V.},
   title = {Introducing electric field fabrication: A method of additive manufacturing via liquid dielectrophoresis},
   journal = {Addit Manuf Lett},
   volume = {4},
   note = {2772-3690
Duncan, Josie L
Schultz, Jeff
Barlow, Zeke
Davalos, Rafael V
R43 TR003968/TR/NCATS NIH HHS/United States
Journal Article
Netherlands
2023/02/24
Addit Manuf Lett. 2023 Feb;4:100107. doi: 10.1016/j.addlet.2022.100107. Epub 2022 Nov 28.},
   abstract = {Biomedical devices with millimeter and micron-scaled features have been a promising approach to single-cell analysis, diagnostics, and fundamental biological and chemical studies. These devices, however, have not been able to fully embrace the advantages of additive manufacturing (AM) that offers quick prototypes and complexities not achievable via traditional 2D fabrication techniques (e.g., soft lithography). This slow adoption of AM can be attributed in part to limited material selection, resolution, and inability to easily integrate components mid-print. Here, we present the feasibility of using liquid dielectrophoresis to manipulate and shape a droplet of build material, paired with subsequent curing and stacking, to generate 3D parts. This Electric Field Fabrication (EFF) technique is an additive manufacturing method that offers advantages such as new printable materials and mixed-media parts without post-assembly for biomedical applications.},
   keywords = {Dielectrophoresis
Electrokinetics
Field-assisted printing
Microfluidics
Polymers},
   ISSN = {2772-3690},
   DOI = {10.1016/j.addlet.2022.100107},
   year = {2023},
   type = {Journal Article}
}

Biomedical devices with millimeter and micron-scaled features have been a promising approach to single-cell analysis, diagnostics, and fundamental biological and chemical studies. These devices, however, have not been able to fully embrace the advantages of additive manufacturing (AM) that offers quick prototypes and complexities not achievable via traditional 2D fabrication techniques (e.g., soft lithography). This slow adoption of AM can be attributed in part to limited material selection, resolution, and inability to easily integrate components mid-print. Here, we present the feasibility of using liquid dielectrophoresis to manipulate and shape a droplet of build material, paired with subsequent curing and stacking, to generate 3D parts. This Electric Field Fabrication (EFF) technique is an additive manufacturing method that offers advantages such as new printable materials and mixed-media parts without post-assembly for biomedical applications.

@article{RN88,
   author = {Graybill, P. M. and Jacobs, E. J. th and Jana, A. and Agashe, A. and Nain, A. S. and Davalos, R. V.},
   title = {Ultra-thin and ultra-porous nanofiber networks as a basement-membrane mimic},
   journal = {Lab Chip},
   volume = {23},
   number = {20},
   pages = {4565-4578},
   note = {1473-0189
Graybill, Philip M
Orcid: 0000-0002-2057-7478
Jacobs, Edward J 4th
Orcid: 0000-0002-6130-2411
Jana, Aniket
Agashe, Atharva
Nain, Amrinder S
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
P01 CA207206/CA/NCI NIH HHS/United States
R44 TR003968/TR/NCATS NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2023/09/29
Lab Chip. 2023 Oct 10;23(20):4565-4578. doi: 10.1039/d3lc00304c.},
   abstract = {Current basement membrane (BM) mimics used for modeling endothelial and epithelial barriers in vitro do not faithfully recapitulate key in vivo physiological properties such as BM thickness, porosity, stiffness, and fibrous composition. Here, we use networks of precisely arranged nanofibers to form ultra-thin (∼3 μm thick) and ultra-porous (∼90%) BM mimics for blood-brain barrier modeling. We show that these nanofiber networks enable close contact between endothelial monolayers and pericytes across the membrane, which are known to regulate barrier tightness. Cytoskeletal staining and transendothelial electrical resistance (TEER) measurements reveal barrier formation on nanofiber membranes integrated within microfluidic devices and transwell inserts. Further, significantly higher TEER values indicate a biological benefit for co-cultures formed on the ultra-thin nanofiber membranes. Our BM mimic overcomes critical technological challenges in forming co-cultures that are in proximity and facilitate cell-cell contact, while still being constrained to their respective sides. We anticipate that our nanofiber networks will find applications in drug discovery, cell migration, and barrier dysfunction studies.},
   keywords = {*Nanofibers
Porosity
Blood-Brain Barrier/physiology
Coculture Techniques
Basement Membrane},
   ISSN = {1473-0197 (Print)
1473-0189},
   DOI = {10.1039/d3lc00304c},
   year = {2023},
   type = {Journal Article}
}

Current basement membrane (BM) mimics used for modeling endothelial and epithelial barriers in vitro do not faithfully recapitulate key in vivo physiological properties such as BM thickness, porosity, stiffness, and fibrous composition. Here, we use networks of precisely arranged nanofibers to form ultra-thin (∼3 μm thick) and ultra-porous (∼90%) BM mimics for blood-brain barrier modeling. We show that these nanofiber networks enable close contact between endothelial monolayers and pericytes across the membrane, which are known to regulate barrier tightness. Cytoskeletal staining and transendothelial electrical resistance (TEER) measurements reveal barrier formation on nanofiber membranes integrated within microfluidic devices and transwell inserts. Further, significantly higher TEER values indicate a biological benefit for co-cultures formed on the ultra-thin nanofiber membranes. Our BM mimic overcomes critical technological challenges in forming co-cultures that are in proximity and facilitate cell-cell contact, while still being constrained to their respective sides. We anticipate that our nanofiber networks will find applications in drug discovery, cell migration, and barrier dysfunction studies.

@article{RN93,
   author = {Jacobs, E. J. th and Campelo, S. N. and Aycock, K. N. and Yao, D. and Davalos, R. V.},
   title = {Spatiotemporal estimations of temperature rise during electroporation treatments using a deep neural network},
   journal = {Comput Biol Med},
   volume = {161},
   pages = {107019},
   note = {1879-0534
Jacobs, Edward J 4th
Campelo, Sabrina N
Aycock, Kenneth N
Yao, Danfeng
Davalos, Rafael V
Journal Article
Research Support, N.I.H., Extramural
United States
2023/05/24
Comput Biol Med. 2023 Jul;161:107019. doi: 10.1016/j.compbiomed.2023.107019. Epub 2023 May 16.},
   abstract = {The nonthermal mechanism for irreversible electroporation has been paramount for treating tumors and cardiac tissue in anatomically sensitive areas, where there is concern about damage to nearby bowels, ducts, blood vessels, or nerves. However, Joule heating still occurs as a secondary effect of applying current through a resistive tissue and must be minimized to maintain the benefits of electroporation at high voltages. Numerous thermal mitigation protocols have been proposed to minimize temperature rise, but intraoperative temperature monitoring is still needed. We show that an accurate and robust temperature prediction AI model can be developed using estimated tissue properties (bulk and dynamic conductivity), known geometric properties (probe spacing), and easily measurable treatment parameters (applied voltage, current, and pulse number). We develop the 2-layer neural network on realistic 2D finite element model simulations with conditions encompassing most electroporation applications. Calculating feature contributions, we found that temperature prediction is mostly dependent on current and pulse number and show that the model remains accurate when incorrect tissue properties are intentionally used as input parameters. Lastly, we show that the model can predict temperature rise within ex vivo perfused porcine livers, with error <0.5 °C. This model, using easily acquired parameters, is shown to predict temperature rise in over 1000 unique test conditions with <1 °C error and no observable outliers. We believe the use of simple, readily available input parameters would allow this model to be incorporated in many already available electroporation systems for real-time temperature estimations.},
   keywords = {Swine
Animals
Temperature
*Electroporation/methods
*Electroporation Therapies
Electric Conductivity
Neural Networks, Computer
Artificial intelligence
Electroporation
Pulsed electric field
Thermal heating
Tissue ablations},
   ISSN = {0010-4825},
   DOI = {10.1016/j.compbiomed.2023.107019},
   year = {2023},
   type = {Journal Article}
}

The nonthermal mechanism for irreversible electroporation has been paramount for treating tumors and cardiac tissue in anatomically sensitive areas, where there is concern about damage to nearby bowels, ducts, blood vessels, or nerves. However, Joule heating still occurs as a secondary effect of applying current through a resistive tissue and must be minimized to maintain the benefits of electroporation at high voltages. Numerous thermal mitigation protocols have been proposed to minimize temperature rise, but intraoperative temperature monitoring is still needed. We show that an accurate and robust temperature prediction AI model can be developed using estimated tissue properties (bulk and dynamic conductivity), known geometric properties (probe spacing), and easily measurable treatment parameters (applied voltage, current, and pulse number). We develop the 2-layer neural network on realistic 2D finite element model simulations with conditions encompassing most electroporation applications. Calculating feature contributions, we found that temperature prediction is mostly dependent on current and pulse number and show that the model remains accurate when incorrect tissue properties are intentionally used as input parameters. Lastly, we show that the model can predict temperature rise within ex vivo perfused porcine livers, with error <0.5 °C. This model, using easily acquired parameters, is shown to predict temperature rise in over 1000 unique test conditions with <1 °C error and no observable outliers. We believe the use of simple, readily available input parameters would allow this model to be incorporated in many already available electroporation systems for real-time temperature estimations.

@article{RN96,
   author = {Jacobs Iv, E. J. and Graybill, P. M. and Jana, A. and Agashe, A. and Nain, A. S. and Davalos, R. V.},
   title = {Engineering high post-electroporation viabilities and transfection efficiencies for elongated cells on suspended nanofiber networks},
   journal = {Bioelectrochemistry},
   volume = {152},
   pages = {108415},
   note = {1878-562x
Jacobs Iv, Edward J
Graybill, Philip M
Jana, Aniket
Agashe, Atharva
Nain, Amrinder S
Davalos, Rafael V
Journal Article
Netherlands
2023/04/04
Bioelectrochemistry. 2023 Aug;152:108415. doi: 10.1016/j.bioelechem.2023.108415. Epub 2023 Mar 21.},
   abstract = {The impact of cell shape on cell membrane permeabilization by pulsed electric fields is not fully understood. For certain applications, cell survival and recovery post-treatment is either desirable, as in gene transfection, electrofusion, and electrochemotherapy, or is undesirable, as in tumor and cardiac ablations. Understanding of how morphology affects cell viability post-electroporation may lead to improved electroporation methods. In this study, we use precisely aligned nanofiber networks within a microfluidic device to reproducibly generate elongated cells with controlled orientations to an applied electric field. We show that cell viability is significantly dependent on cell orientation, elongation, and spread. Further, these trends are dependent on the external buffer conductivity. Additionally, we see that cell survival for elongated cells is still supported by the standard pore model of electroporation. Lastly, we see that manipulating the cell orientation and shape can be leveraged for increased transfection efficiencies when compared to spherical cells. An improved understanding of cell shape and pulsation buffer conductivity may lead to improved methods for enhancing cell viability post-electroporation by engineering the cell morphology, cytoskeleton, and electroporation buffer conditions.},
   keywords = {Humans
*Nanofibers
Electroporation/methods
Transfection
*Electrochemotherapy/methods
*Neoplasms
Cell Survival
Cytoskeleton
Electroporation
Nanofibers
Pulsed Electric Fields
Viability},
   ISSN = {1567-5394},
   DOI = {10.1016/j.bioelechem.2023.108415},
   year = {2023},
   type = {Journal Article}
}

The impact of cell shape on cell membrane permeabilization by pulsed electric fields is not fully understood. For certain applications, cell survival and recovery post-treatment is either desirable, as in gene transfection, electrofusion, and electrochemotherapy, or is undesirable, as in tumor and cardiac ablations. Understanding of how morphology affects cell viability post-electroporation may lead to improved electroporation methods. In this study, we use precisely aligned nanofiber networks within a microfluidic device to reproducibly generate elongated cells with controlled orientations to an applied electric field. We show that cell viability is significantly dependent on cell orientation, elongation, and spread. Further, these trends are dependent on the external buffer conductivity. Additionally, we see that cell survival for elongated cells is still supported by the standard pore model of electroporation. Lastly, we see that manipulating the cell orientation and shape can be leveraged for increased transfection efficiencies when compared to spherical cells. An improved understanding of cell shape and pulsation buffer conductivity may lead to improved methods for enhancing cell viability post-electroporation by engineering the cell morphology, cytoskeleton, and electroporation buffer conditions.

@article{RN95,
   author = {Perera-Bel, E. and Aycock, K. N. and Salameh, Z. S. and Gomez-Barea, M. and Davalos, R. V. and Ivorra, A. and Ballester, M. A. G.},
   title = {PIRET-A Platform for Treatment Planning in Electroporation-Based Therapies},
   journal = {IEEE Trans Biomed Eng},
   volume = {70},
   number = {6},
   pages = {1902-1910},
   note = {1558-2531
Perera-Bel, Enric
Aycock, Kenneth N
Salameh, Zaid S
Gomez-Barea, Mario
Davalos, Rafael V
Ivorra, Antoni
Ballester, Miguel A Gonzalez
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2023/04/05
IEEE Trans Biomed Eng. 2023 Jun;70(6):1902-1910. doi: 10.1109/TBME.2022.3232038. Epub 2023 May 19.},
   abstract = {Tissue electroporation is the basis of several therapies. Electroporation is performed by briefly exposing tissues to high electric fields. It is generally accepted that electroporation is effective where an electric field magnitude threshold is overreached. However, it is difficult to preoperatively estimate the field distribution because it is highly dependent on anatomy and treatment parameters. OBJECTIVE: We developed PIRET, a platform to predict the treatment volume in electroporation-based therapies. METHODS: The platform seamlessly integrates tools to build patient-specific models where the electric field is simulated to predict the treatment volume. Patient anatomy is segmented from medical images and 3D reconstruction aids in placing the electrodes and setting up treatment parameters. RESULTS: Four canine patients that had been treated with high-frequency irreversible electroporation were retrospectively planned with PIRET and with a workflow commonly used in previous studies, which uses different general-purpose segmentation (3D Slicer) and modeling software (3Matic and COMSOL Multiphysics). PIRET outperformed the other workflow by 65 minutes (× 1.7 faster), thanks to the improved user experience during treatment setup and model building. Both approaches computed similarly accurate electric field distributions, with average Dice scores higher than 0.93. CONCLUSION: A platform which integrates all the required tools for electroporation treatment planning is presented. Treatment plan can be performed rapidly with minimal user interaction in a stand-alone platform. SIGNIFICANCE: This platform is, to the best of our knowledge, the most complete software for treatment planning of irreversible electroporation. It can potentially be used for other electroporation applications.},
   keywords = {Animals
Dogs
*Electrochemotherapy/methods
Retrospective Studies
Electroporation/methods
Software
Electroporation Therapies},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/tbme.2022.3232038},
   year = {2023},
   type = {Journal Article}
}

Tissue electroporation is the basis of several therapies. Electroporation is performed by briefly exposing tissues to high electric fields. It is generally accepted that electroporation is effective where an electric field magnitude threshold is overreached. However, it is difficult to preoperatively estimate the field distribution because it is highly dependent on anatomy and treatment parameters. OBJECTIVE: We developed PIRET, a platform to predict the treatment volume in electroporation-based therapies. METHODS: The platform seamlessly integrates tools to build patient-specific models where the electric field is simulated to predict the treatment volume. Patient anatomy is segmented from medical images and 3D reconstruction aids in placing the electrodes and setting up treatment parameters. RESULTS: Four canine patients that had been treated with high-frequency irreversible electroporation were retrospectively planned with PIRET and with a workflow commonly used in previous studies, which uses different general-purpose segmentation (3D Slicer) and modeling software (3Matic and COMSOL Multiphysics). PIRET outperformed the other workflow by 65 minutes (× 1.7 faster), thanks to the improved user experience during treatment setup and model building. Both approaches computed similarly accurate electric field distributions, with average Dice scores higher than 0.93. CONCLUSION: A platform which integrates all the required tools for electroporation treatment planning is presented. Treatment plan can be performed rapidly with minimal user interaction in a stand-alone platform. SIGNIFICANCE: This platform is, to the best of our knowledge, the most complete software for treatment planning of irreversible electroporation. It can potentially be used for other electroporation applications.

@article{RN99,
   author = {Zhang, Y. and Wu, X. and Vadlamani, R. A. and Lim, Y. and Kim, J. and David, K. and Gilbert, E. and Li, Y. and Wang, R. and Jiang, S. and Wang, A. and Sontheimer, H. and English, D. and Emori, S. and Davalos, R. V. and Poelzing, S. and Jia, X.},
   title = {Multifunctional ferromagnetic fiber robots for navigation, sensing, and treatment in minimally invasive surgery},
   journal = {bioRxiv},
   note = {Zhang, Yujing
Wu, Xiaobo
Vadlamani, Ram Anand
Lim, Youngmin
Kim, Jongwoon
David, Kailee
Gilbert, Earl
Li, You
Wang, Ruixuan
Jiang, Shan
Wang, Anbo
Sontheimer, Harald
English, Daniel
Emori, Satoru
Davalos, Rafael V
Poelzing, Steven
Jia, Xiaoting
R01 NS123069/NS/NINDS NIH HHS/United States
Preprint
United States
2023/02/14
bioRxiv [Preprint]. 2023 Jan 30:2023.01.27.525973. doi: 10.1101/2023.01.27.525973.},
   abstract = {Small-scale robots capable of remote active steering and navigation offer great potential for biomedical applications. However, the current design and manufacturing procedure impede their miniaturization and integration of various diagnostic and therapeutic functionalities. Here, we present a robotic fiber platform for integrating navigation, sensing, and therapeutic functions at a submillimeter scale. These fiber robots consist of ferromagnetic, electrical, optical, and microfluidic components, fabricated with a thermal drawing process. Under magnetic actuation, they can navigate through complex and constrained environments, such as artificial vessels and brain phantoms. Moreover, we utilize Langendorff mouse hearts model, glioblastoma microplatforms, and in vivo mouse models to demonstrate the capabilities of sensing electrophysiology signals and performing localized treatment. Additionally, we demonstrate that the fiber robots can serve as endoscopes with embedded waveguides. These fiber robots provide a versatile platform for targeted multimodal detection and treatment at hard-to-reach locations in a minimally invasive and remotely controllable manner.},
   DOI = {10.1101/2023.01.27.525973},
   year = {2023},
   type = {Journal Article}
}

Small-scale robots capable of remote active steering and navigation offer great potential for biomedical applications. However, the current design and manufacturing procedure impede their miniaturization and integration of various diagnostic and therapeutic functionalities. Here, we present a robotic fiber platform for integrating navigation, sensing, and therapeutic functions at a submillimeter scale. These fiber robots consist of ferromagnetic, electrical, optical, and microfluidic components, fabricated with a thermal drawing process. Under magnetic actuation, they can navigate through complex and constrained environments, such as artificial vessels and brain phantoms. Moreover, we utilize Langendorff mouse hearts model, glioblastoma microplatforms, and in vivo mouse models to demonstrate the capabilities of sensing electrophysiology signals and performing localized treatment. Additionally, we demonstrate that the fiber robots can serve as endoscopes with embedded waveguides. These fiber robots provide a versatile platform for targeted multimodal detection and treatment at hard-to-reach locations in a minimally invasive and remotely controllable manner.

@article{RN91,
   author = {Zhang, Y. and Wu, X. and Vadlamani, R. A. and Lim, Y. and Kim, J. and David, K. and Gilbert, E. and Li, Y. and Wang, R. and Jiang, S. and Wang, A. and Sontheimer, H. and English, D. F. and Emori, S. and Davalos, R. V. and Poelzing, S. and Jia, X.},
   title = {Submillimeter Multifunctional Ferromagnetic Fiber Robots for Navigation, Sensing, and Modulation},
   journal = {Adv Healthc Mater},
   volume = {12},
   number = {28},
   pages = {e2300964},
   note = {2192-2659
Zhang, Yujing
Wu, Xiaobo
Vadlamani, Ram Anand
Lim, Youngmin
Kim, Jongwoon
David, Kailee
Gilbert, Earl
Li, You
Wang, Ruixuan
Jiang, Shan
Wang, Anbo
Sontheimer, Harald
English, Daniel Fine
Emori, Satoru
Davalos, Rafael V
Poelzing, Steven
Jia, Xiaoting
Orcid: 0000-0003-4890-6103
R01 NS123069/NS/NINDS NIH HHS/United States
R21 EY033080/EY/NEI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
Germany
2023/07/21
Adv Healthc Mater. 2023 Nov;12(28):e2300964. doi: 10.1002/adhm.202300964. Epub 2023 Jul 27.},
   abstract = {Small-scale robots capable of remote active steering and navigation offer great potential for biomedical applications. However, the current design and manufacturing procedure impede their miniaturization and integration of various diagnostic and therapeutic functionalities. Herein, submillimeter fiber robots that can integrate navigation, sensing, and modulation functions are presented. These fiber robots are fabricated through a scalable thermal drawing process at a speed of 4 meters per minute, which enables the integration of ferromagnetic, electrical, optical, and microfluidic composite with an overall diameter of as small as 250 µm and a length of as long as 150 m. The fiber tip deflection angle can reach up to 54(o) under a uniform magnetic field of 45 mT. These fiber robots can navigate through complex and constrained environments, such as artificial vessels and brain phantoms. Moreover, Langendorff mouse hearts model, glioblastoma micro platforms, and in vivo mouse models are utilized to demonstrate the capabilities of sensing electrophysiology signals and performing a localized treatment. Additionally, it is demonstrated that the fiber robots can serve as endoscopes with embedded waveguides. These fiber robots provide a versatile platform for targeted multimodal detection and treatment at hard-to-reach locations in a minimally invasive and remotely controllable manner.},
   keywords = {Animals
Mice
*Robotics/methods
Equipment Design
Miniaturization
Magnetic Fields
biomedical engineering
ferromagnetic robotics
fiber robots
micro robotics
thermal drawing},
   ISSN = {2192-2640 (Print)
2192-2640},
   DOI = {10.1002/adhm.202300964},
   year = {2023},
   type = {Journal Article}
}

Small-scale robots capable of remote active steering and navigation offer great potential for biomedical applications. However, the current design and manufacturing procedure impede their miniaturization and integration of various diagnostic and therapeutic functionalities. Herein, submillimeter fiber robots that can integrate navigation, sensing, and modulation functions are presented. These fiber robots are fabricated through a scalable thermal drawing process at a speed of 4 meters per minute, which enables the integration of ferromagnetic, electrical, optical, and microfluidic composite with an overall diameter of as small as 250 µm and a length of as long as 150 m. The fiber tip deflection angle can reach up to 54(o) under a uniform magnetic field of 45 mT. These fiber robots can navigate through complex and constrained environments, such as artificial vessels and brain phantoms. Moreover, Langendorff mouse hearts model, glioblastoma micro platforms, and in vivo mouse models are utilized to demonstrate the capabilities of sensing electrophysiology signals and performing a localized treatment. Additionally, it is demonstrated that the fiber robots can serve as endoscopes with embedded waveguides. These fiber robots provide a versatile platform for targeted multimodal detection and treatment at hard-to-reach locations in a minimally invasive and remotely controllable manner.

@article{RN104,
   author = {Aycock, K. N. and Campelo, S. N. and Davalos, R. V.},
   title = {A Comparative Modeling Study of Thermal Mitigation Strategies in Irreversible Electroporation Treatments},
   journal = {J Heat Transfer},
   volume = {144},
   number = {3},
   pages = {031206},
   note = {1528-8943
Aycock, Kenneth N
Campelo, Sabrina N
Davalos, Rafael V
Journal Article
United States
2022/07/15
J Heat Transfer. 2022 Mar 1;144(3):031206. doi: 10.1115/1.4053199. Epub 2022 Jan 18.},
   abstract = {Irreversible electroporation (IRE), also referred to as nonthermal pulsed field ablation (PFA), is an attractive focal ablation modality for solid tumors and cardiac tissue due to its ability to destroy aberrant cells with limited disruption of the underlying tissue architecture. Despite its nonthermal cell death mechanism, application of electrical energy results in Joule heating that, if ignored, can cause undesired thermal injury. Engineered thermal mitigation (TM) technologies including phase change materials (PCMs) and active cooling (AC) have been reported and tested as a potential means to limit thermal damage. However, several variables affect TM performance including the pulsing paradigm, electrode geometry, PCM composition, and chosen active cooling parameters, meaning direct comparisons between approaches are lacking. In this study, we developed a computational model of conventional bipolar and monopolar probes with solid, PCM-filled, or actively cooled cores to simulate clinical IRE treatments in pancreatic tissue. This approach reveals that probes with integrated PCM cores can be tuned to drastically limit thermal damage compared to existing solid probes. Furthermore, actively cooled probes provide additional control over thermal effects within the probe vicinity and can altogether abrogate thermal damage. In practice, such differences in performance must be weighed against the increased time, expense, and effort required for modified probes compared to existing solid probes.},
   ISSN = {0022-1481 (Print)
0022-1481},
   DOI = {10.1115/1.4053199},
   year = {2022},
   type = {Journal Article}
}

Irreversible electroporation (IRE), also referred to as nonthermal pulsed field ablation (PFA), is an attractive focal ablation modality for solid tumors and cardiac tissue due to its ability to destroy aberrant cells with limited disruption of the underlying tissue architecture. Despite its nonthermal cell death mechanism, application of electrical energy results in Joule heating that, if ignored, can cause undesired thermal injury. Engineered thermal mitigation (TM) technologies including phase change materials (PCMs) and active cooling (AC) have been reported and tested as a potential means to limit thermal damage. However, several variables affect TM performance including the pulsing paradigm, electrode geometry, PCM composition, and chosen active cooling parameters, meaning direct comparisons between approaches are lacking. In this study, we developed a computational model of conventional bipolar and monopolar probes with solid, PCM-filled, or actively cooled cores to simulate clinical IRE treatments in pancreatic tissue. This approach reveals that probes with integrated PCM cores can be tuned to drastically limit thermal damage compared to existing solid probes. Furthermore, actively cooled probes provide additional control over thermal effects within the probe vicinity and can altogether abrogate thermal damage. In practice, such differences in performance must be weighed against the increased time, expense, and effort required for modified probes compared to existing solid probes.

@article{RN102,
   author = {Aycock, K. N. and Campelo, S. N. and Salameh, Z. S. and Vadlamani, R. A. and Lorenzo, M. F. and Davalos, R. V.},
   title = {Extended interpulse delays improve therapeutic efficacy of microsecond-duration pulsed electric fields},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2022},
   pages = {5021-5024},
   note = {2694-0604
Aycock, Kenneth N
Campelo, Sabrina N
Salameh, Zaid S
Vadlamani, Ram Anand
Lorenzo, Melvin F
Davalos, Rafael V
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2022/09/11
Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:5021-5024. doi: 10.1109/EMBC48229.2022.9871737.},
   abstract = {Irreversible electroporation (IRE), or pulsed field ablation, employs microsecond-duration pulsed electric fields to generate targeted cellular damage without injury to the underlying tissue architecture. Biphasic, burst-type waveforms (termed high-frequency IRE, or H-FIRE) have garnered attention for their ability to elicit clinically relevant ablation volumes while reducing several undesirable side effects (muscle contractions/electrochemical effects) seen with monophasic pulses. Pulse width is generally the main (or only) parameter considered during burst construction, with little attention given to the delays within the burst. In this work, we tested the hypothesis that H-FIRE waveforms could be further optimized by manipulating only the interpulse delay between biphasic pulses within each burst. Using benchtop, ex vivo, and in vivo models, we demonstrate that extended interpulse delays (i.e., ~100 μs) reduce the severity of induced muscle contractions, alleviate mechanical tissue destruction, and minimize the chances of electrical arcing. Clinical Relevance- This proof-of-concept study shows that H-FIRE waveforms with extended interpulse delays provide several therapeutic benefits over conventional waveforms.},
   keywords = {*Electricity
*Electroporation
Muscle Contraction/physiology},
   ISSN = {2375-7477},
   DOI = {10.1109/embc48229.2022.9871737},
   year = {2022},
   type = {Journal Article}
}

Irreversible electroporation (IRE), or pulsed field ablation, employs microsecond-duration pulsed electric fields to generate targeted cellular damage without injury to the underlying tissue architecture. Biphasic, burst-type waveforms (termed high-frequency IRE, or H-FIRE) have garnered attention for their ability to elicit clinically relevant ablation volumes while reducing several undesirable side effects (muscle contractions/electrochemical effects) seen with monophasic pulses. Pulse width is generally the main (or only) parameter considered during burst construction, with little attention given to the delays within the burst. In this work, we tested the hypothesis that H-FIRE waveforms could be further optimized by manipulating only the interpulse delay between biphasic pulses within each burst. Using benchtop, ex vivo, and in vivo models, we demonstrate that extended interpulse delays (i.e.,  100 μs) reduce the severity of induced muscle contractions, alleviate mechanical tissue destruction, and minimize the chances of electrical arcing. Clinical Relevance- This proof-of-concept study shows that H-FIRE waveforms with extended interpulse delays provide several therapeutic benefits over conventional waveforms.

@article{RN109,
   author = {Aycock, K. N. and Vadlamani, R. A. and Jacobs, E. J. and Imran, K. M. and Verbridge, S. S. and Allen, I. C. and Manuchehrabadi, N. and Davalos, R. V.},
   title = {Experimental and Numerical Investigation of Parameters Affecting High-Frequency Irreversible Electroporation for Prostate Cancer Ablation},
   journal = {J Biomech Eng},
   volume = {144},
   number = {6},
   note = {1528-8951
Aycock, Kenneth N
Vadlamani, Ram Anand
Jacobs, Edward J
Imran, Khan Mohammad
Verbridge, Scott S
Allen, Irving C
Manuchehrabadi, Navid
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2022/01/20
J Biomech Eng. 2022 Jun 1;144(6):061003. doi: 10.1115/1.4053595.},
   abstract = {While the primary goal of focal therapy for prostate cancer (PCa) is conserving patient quality of life by reducing oncological burden, available modalities use thermal energy or whole-gland radiation which can damage critical neurovascular structures within the prostate and increase risk of genitourinary dysfunction. High-frequency irreversible electroporation (H-FIRE) is a promising alternative ablation modality that utilizes bursts of pulsed electric fields (PEFs) to destroy aberrant cells via targeted membrane damage. Due to its nonthermal mechanism, H-FIRE offers several advantages over state-of-the-art treatments, but waveforms have not been optimized for treatment of PCa. In this study, we characterize lethal electric field thresholds (EFTs) for H-FIRE waveforms with three different pulse widths as well as three interpulse delays in vitro and compare them to conventional irreversible electroporation (IRE). Experiments were performed in non-neoplastic and malignant prostate cells to determine the effect of waveforms on both targeted (malignant) and adjacent (non-neoplastic) tissue. A numerical modeling approach was developed to estimate the clinical effects of each waveform including extent of nonthermal ablation, undesired thermal damage, and nerve excitation. Our findings indicate that H-FIRE waveforms with pulse durations of 5 and 10 μs provide large ablations comparable to IRE with tolerable levels of thermal damage and minimized muscle contractions. Lower duration (2 μs) H-FIRE waveforms exhibit the least amount of muscle contractions but require increased voltages which may be accompanied by unwanted thermal damage.},
   keywords = {*Electroporation
Heart Rate
Humans
Male
Muscle Contraction
*Prostatic Neoplasms/surgery
Quality of Life},
   ISSN = {0148-0731},
   DOI = {10.1115/1.4053595},
   year = {2022},
   type = {Journal Article}
}

While the primary goal of focal therapy for prostate cancer (PCa) is conserving patient quality of life by reducing oncological burden, available modalities use thermal energy or whole-gland radiation which can damage critical neurovascular structures within the prostate and increase risk of genitourinary dysfunction. High-frequency irreversible electroporation (H-FIRE) is a promising alternative ablation modality that utilizes bursts of pulsed electric fields (PEFs) to destroy aberrant cells via targeted membrane damage. Due to its nonthermal mechanism, H-FIRE offers several advantages over state-of-the-art treatments, but waveforms have not been optimized for treatment of PCa. In this study, we characterize lethal electric field thresholds (EFTs) for H-FIRE waveforms with three different pulse widths as well as three interpulse delays in vitro and compare them to conventional irreversible electroporation (IRE). Experiments were performed in non-neoplastic and malignant prostate cells to determine the effect of waveforms on both targeted (malignant) and adjacent (non-neoplastic) tissue. A numerical modeling approach was developed to estimate the clinical effects of each waveform including extent of nonthermal ablation, undesired thermal damage, and nerve excitation. Our findings indicate that H-FIRE waveforms with pulse durations of 5 and 10 μs provide large ablations comparable to IRE with tolerable levels of thermal damage and minimized muscle contractions. Lower duration (2 μs) H-FIRE waveforms exhibit the least amount of muscle contractions but require increased voltages which may be accompanied by unwanted thermal damage.

@article{RN101,
   author = {Campelo, S. N. and Jacobs, E. J. th and Aycock, K. N. and Davalos, R. V.},
   title = {Real-Time Temperature Rise Estimation during Irreversible Electroporation Treatment through State-Space Modeling},
   journal = {Bioengineering (Basel)},
   volume = {9},
   number = {10},
   note = {2306-5354
Campelo, Sabrina N
Orcid: 0000-0001-6570-7427
Jacobs, Edward J 4th
Aycock, Kenneth N
Orcid: 0000-0003-3885-6798
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
R01 CA24047/NH/NIH HHS/United States
Journal Article
Switzerland
2022/10/28
Bioengineering (Basel). 2022 Sep 23;9(10):499. doi: 10.3390/bioengineering9100499.},
   abstract = {To evaluate the feasibility of real-time temperature monitoring during an electroporation-based therapy procedure, a data-driven state-space model was developed. Agar phantoms mimicking low conductivity (LC) and high conductivity (HC) tissues were tested under the influences of high (HV) and low (LV) applied voltages. Real-time changes in impedance, measured by Fourier Analysis SpecTroscopy (FAST) along with the known tissue conductivity and applied voltages, were used to train the model. A theoretical finite element model was used for external validation of the model, producing model fits of 95.8, 88.4, 90.7, and 93.7% at 4 mm and 93.2, 58.9, 90.0, and 90.1% at 10 mm for the HV-HC, LV-LC, HV-LC, and LV-HC groups, respectively. The proposed model suggests that real-time temperature monitoring may be achieved with good accuracy through the use of real-time impedance monitoring.},
   keywords = {H-fire
Pfa
agar phantom
black-box modeling
electroporation
pulsed field ablation
temperature prediction
thermal mitigation},
   ISSN = {2306-5354 (Print)
2306-5354},
   DOI = {10.3390/bioengineering9100499},
   year = {2022},
   type = {Journal Article}
}

To evaluate the feasibility of real-time temperature monitoring during an electroporation-based therapy procedure, a data-driven state-space model was developed. Agar phantoms mimicking low conductivity (LC) and high conductivity (HC) tissues were tested under the influences of high (HV) and low (LV) applied voltages. Real-time changes in impedance, measured by Fourier Analysis SpecTroscopy (FAST) along with the known tissue conductivity and applied voltages, were used to train the model. A theoretical finite element model was used for external validation of the model, producing model fits of 95.8, 88.4, 90.7, and 93.7% at 4 mm and 93.2, 58.9, 90.0, and 90.1% at 10 mm for the HV-HC, LV-LC, HV-LC, and LV-HC groups, respectively. The proposed model suggests that real-time temperature monitoring may be achieved with good accuracy through the use of real-time impedance monitoring.

@article{RN107,
   author = {Garcia Mora, J. K. and Robertson, J. and Hsu, F. C. and Shinn, R. L. and Larson, M. M. and Rylander, C. G. and Whitlow, C. T. and Debinski, W. and Davalos, R. V. and G, B. Daniel and Rossmeisl, J. H.},
   title = {Comparison of linear and volumetric criteria for the determination of therapeutic response in dogs with intracranial gliomas},
   journal = {J Vet Intern Med},
   volume = {36},
   number = {3},
   pages = {1066-1074},
   note = {1939-1676
Garcia Mora, Josefa Karina
Robertson, John
Hsu, Fang-Chi
Shinn, Richard Levon
Orcid: 0000-0003-4308-4374
Larson, Martha M
Rylander, Christopher G
Whitlow, Christopher T
Debinski, Waldemar
Davalos, Rafael V
B Daniel, Gregory
Rossmeisl, John H
Orcid: 0000-0003-1655-7076
P01CA207206/CA/NCI NIH HHS/United States
R01 CA213423/CA/NCI NIH HHS/United States
R01CA213423/CA/NCI NIH HHS/United States
NH/NIH HHS/United States
United States Department of Health and Human Services/
P01 CA207206/CA/NCI NIH HHS/United States
Comparative Study
Journal Article
United States
2022/03/12
J Vet Intern Med. 2022 May;36(3):1066-1074. doi: 10.1111/jvim.16406. Epub 2022 Mar 11.},
   abstract = {BACKGROUND: Brain tumor therapeutic responses can be quantified from magnetic resonance images (MRI) using 1- (1D) and 2-dimensional (2D) linear and volumetric methods, but few studies in dogs compare these techniques. HYPOTHESES: Linear methods will be obtained faster, but have less agreement than volumetric measurements. Therapeutic response agreement will be highest with the total T2W tumor volumetric (TTV) method. Therapeutic response at 6-weeks will correlate with overall survival (OS). ANIMALS: Forty-six dogs with intracranial gliomas. METHODS: Prospective study. Three raters measured tumors using 1D and 2D linear, TTV, and contrast-enhancing volumetric (CEV) techniques on 143 brain MRI to determine agreement between methods, define therapeutic responses, and assess relations with OS. RESULTS: Raters performed 1D the fastest (2.9 ± 0.57 minutes) and CEV slowest (17.8 ± 6.2 minutes). Inter- and intraobserver agreements were excellent (intraclass correlations ≥.91) across methods. Correlations between linear (1D vs 2D; ρ > .91) and volumetric (TTV vs CEV; ρ > .73) methods were stronger than linear to volumetric comparisons (ρ range, .26-.59). Incorporating clinical and imaging data resulted in fewer discordant therapeutic responses across methods. Dogs having partial tumor responses at 6 weeks had a lower death hazard than dogs with stable or progressive disease when assessed using 2D, CEV, and TTV (hazard ration 2.1; 95% confidence interval, 1.22-3.63; P = .008). CONCLUSIONS AND CLINICAL IMPORTANCE: One-dimensional, 2D, CEV, and TTV are comparable for determining therapeutic response. Given the simplicity, universal applicability, and superior performance of the TTV, we recommend its use to standardize glioma therapeutic response criteria.},
   keywords = {Animals
Brain Neoplasms/diagnostic imaging/drug therapy/*veterinary
Dog Diseases/*diagnostic imaging/drug therapy
Dogs
Glioma/diagnostic imaging/drug therapy/*veterinary
Magnetic Resonance Imaging/veterinary
Prospective Studies
Treatment Outcome
dog
magnetic resonance imaging
neurooncology
neuroradiology
radiology and diagnostic imaging},
   ISSN = {0891-6640 (Print)
0891-6640},
   DOI = {10.1111/jvim.16406},
   year = {2022},
   type = {Journal Article}
}

BACKGROUND: Brain tumor therapeutic responses can be quantified from magnetic resonance images (MRI) using 1- (1D) and 2-dimensional (2D) linear and volumetric methods, but few studies in dogs compare these techniques. HYPOTHESES: Linear methods will be obtained faster, but have less agreement than volumetric measurements. Therapeutic response agreement will be highest with the total T2W tumor volumetric (TTV) method. Therapeutic response at 6-weeks will correlate with overall survival (OS). ANIMALS: Forty-six dogs with intracranial gliomas. METHODS: Prospective study. Three raters measured tumors using 1D and 2D linear, TTV, and contrast-enhancing volumetric (CEV) techniques on 143 brain MRI to determine agreement between methods, define therapeutic responses, and assess relations with OS. RESULTS: Raters performed 1D the fastest (2.9 ± 0.57 minutes) and CEV slowest (17.8 ± 6.2 minutes). Inter- and intraobserver agreements were excellent (intraclass correlations ≥.91) across methods. Correlations between linear (1D vs 2D; ρ > .91) and volumetric (TTV vs CEV; ρ > .73) methods were stronger than linear to volumetric comparisons (ρ range, .26-.59). Incorporating clinical and imaging data resulted in fewer discordant therapeutic responses across methods. Dogs having partial tumor responses at 6 weeks had a lower death hazard than dogs with stable or progressive disease when assessed using 2D, CEV, and TTV (hazard ration 2.1; 95% confidence interval, 1.22-3.63; P = .008). CONCLUSIONS AND CLINICAL IMPORTANCE: One-dimensional, 2D, CEV, and TTV are comparable for determining therapeutic response. Given the simplicity, universal applicability, and superior performance of the TTV, we recommend its use to standardize glioma therapeutic response criteria.

@article{RN106,
   author = {Imran, K. M. and Nagai-Singer, M. A. and Brock, R. M. and Alinezhadbalalami, N. and Davalos, R. V. and Allen, I. C.},
   title = {Exploration of Novel Pathways Underlying Irreversible Electroporation Induced Anti-Tumor Immunity in Pancreatic Cancer},
   journal = {Front Oncol},
   volume = {12},
   pages = {853779},
   note = {2234-943x
Imran, Khan Mohammad
Nagai-Singer, Margaret A
Brock, Rebecca M
Alinezhadbalalami, Nastaran
Davalos, Rafael V
Allen, Irving Coy
R01 CA213423/CA/NCI NIH HHS/United States
R21 EB028429/EB/NIBIB NIH HHS/United States
Journal Article
Review
Switzerland
2022/04/05
Front Oncol. 2022 Mar 18;12:853779. doi: 10.3389/fonc.2022.853779. eCollection 2022.},
   abstract = {Advancements in medical sciences and technologies have significantly improved the survival of many cancers; however, pancreatic cancer remains a deadly diagnosis. This malignancy is often diagnosed late in the disease when metastases have already occurred. Additionally, the location of the pancreas near vital organs limits surgical candidacy, the tumor's immunosuppressive environment limits immunotherapy success, and it is highly resistant to radiation and chemotherapy. Hence, clinicians and patients alike need a treatment paradigm that reduces primary tumor burden, activates systemic anti-tumor immunity, and reverses the local immunosuppressive microenvironment to eventually clear distant metastases. Irreversible electroporation (IRE), a novel non-thermal tumor ablation technique, applies high-voltage ultra-short pulses to permeabilize targeted cell membranes and induce cell death. Progression with IRE technology and an array of research studies have shown that beyond tumor debulking, IRE can induce anti-tumor immune responses possibly through tumor neo-antigen release. However, the success of IRE treatment (i.e. full ablation and tumor recurrence) is variable. We believe that IRE treatment induces IFNγ expression, which then modulates immune checkpoint molecules and thus leads to tumor recurrence. This indicates a co-therapeutic use of IRE and immune checkpoint inhibitors as a promising treatment for pancreatic cancer patients. Here, we review the well-defined and speculated pathways involved in the immunostimulatory effects of IRE treatment for pancreatic cancer, as well as the regulatory pathways that may negate these anti-tumor responses. By defining these underlying mechanisms, future studies may identify improvements to systemic immune system engagement following local tumor ablation with IRE and beyond.},
   keywords = {IFNγ-PD-L1 axis
anti-tumor immunity
immunomodulatory pathways
irreversible electroporation
pancreatic cancer},
   ISSN = {2234-943X (Print)
2234-943x},
   DOI = {10.3389/fonc.2022.853779},
   year = {2022},
   type = {Journal Article}
}

Advancements in medical sciences and technologies have significantly improved the survival of many cancers; however, pancreatic cancer remains a deadly diagnosis. This malignancy is often diagnosed late in the disease when metastases have already occurred. Additionally, the location of the pancreas near vital organs limits surgical candidacy, the tumor's immunosuppressive environment limits immunotherapy success, and it is highly resistant to radiation and chemotherapy. Hence, clinicians and patients alike need a treatment paradigm that reduces primary tumor burden, activates systemic anti-tumor immunity, and reverses the local immunosuppressive microenvironment to eventually clear distant metastases. Irreversible electroporation (IRE), a novel non-thermal tumor ablation technique, applies high-voltage ultra-short pulses to permeabilize targeted cell membranes and induce cell death. Progression with IRE technology and an array of research studies have shown that beyond tumor debulking, IRE can induce anti-tumor immune responses possibly through tumor neo-antigen release. However, the success of IRE treatment (i.e. full ablation and tumor recurrence) is variable. We believe that IRE treatment induces IFNγ expression, which then modulates immune checkpoint molecules and thus leads to tumor recurrence. This indicates a co-therapeutic use of IRE and immune checkpoint inhibitors as a promising treatment for pancreatic cancer patients. Here, we review the well-defined and speculated pathways involved in the immunostimulatory effects of IRE treatment for pancreatic cancer, as well as the regulatory pathways that may negate these anti-tumor responses. By defining these underlying mechanisms, future studies may identify improvements to systemic immune system engagement following local tumor ablation with IRE and beyond.

@article{RN103,
   author = {Kim, J. and Zhao, Y. and Yang, S. and Feng, Z. and Wang, A. and Davalos, R. V. and Jia, X.},
   title = {Laser Machined Fiber-based Microprobe: Application in Microscale Electroporation},
   journal = {Adv Fiber Mater},
   volume = {4},
   number = {4},
   pages = {859-872},
   note = {2524-793x
Kim, Jongwoon
Zhao, Yajun
Yang, Shuo
Feng, Ziang
Wang, Anbo
Davalos, Rafael V
Jia, Xiaoting
R01 CA213423/CA/NCI NIH HHS/United States
R01 NS123069/NS/NINDS NIH HHS/United States
R21 EY033080/EY/NEI NIH HHS/United States
Journal Article
Singapore
2022/08/01
Adv Fiber Mater. 2022 Aug;4(4):859-872. doi: 10.1007/s42765-022-00148-5. Epub 2022 Mar 23.},
   abstract = {Microscale electroporation devices are mostly restricted to in vitro experiments (i.e., microchannel and microcapillary). Novel fiber-based microprobes can enable in vivo microscale electroporation and arbitrarily select the cell groups of interest to electroporate. We developed a flexible, fiber-based microscale electroporation device through a thermal drawing process and femtosecond laser micromachining techniques. The fiber consists of four copper electrodes (80 μm), one microfluidic channel (30 μm), and has an overall diameter of 400 μm. The dimensions of the exposed electrodes and channel were customizable through a delicate femtosecond laser setup. The feasibility of the fiber probe was validated through numerical simulations and in vitro experiments. Successful reversible and irreversible microscale electroporation was observed in a 3D collagen scaffold (seeded with U251 human glioma cells) using fluorescent staining. The ablation regions were estimated by performing the covariance error ellipse method and compared with the numerical simulations. The computational and experimental results of the working fiber-based microprobe suggest the feasibility of in vivo microscale electroporation in space-sensitive areas, such as the deep brain.},
   keywords = {fiber probe
irreversible electroporation
micromachine
microscale electroporation
polymer
reversible electroporation},
   ISSN = {2524-7921 (Print)
2524-7921},
   DOI = {10.1007/s42765-022-00148-5},
   year = {2022},
   type = {Journal Article}
}

Microscale electroporation devices are mostly restricted to in vitro experiments (i.e., microchannel and microcapillary). Novel fiber-based microprobes can enable in vivo microscale electroporation and arbitrarily select the cell groups of interest to electroporate. We developed a flexible, fiber-based microscale electroporation device through a thermal drawing process and femtosecond laser micromachining techniques. The fiber consists of four copper electrodes (80 μm), one microfluidic channel (30 μm), and has an overall diameter of 400 μm. The dimensions of the exposed electrodes and channel were customizable through a delicate femtosecond laser setup. The feasibility of the fiber probe was validated through numerical simulations and in vitro experiments. Successful reversible and irreversible microscale electroporation was observed in a 3D collagen scaffold (seeded with U251 human glioma cells) using fluorescent staining. The ablation regions were estimated by performing the covariance error ellipse method and compared with the numerical simulations. The computational and experimental results of the working fiber-based microprobe suggest the feasibility of in vivo microscale electroporation in space-sensitive areas, such as the deep brain.

@article{RN113,
   author = {Murphy, K. R. and Aycock, K. N. and Hay, A. N. and Rossmeisl, J. H. and Davalos, R. V. and Dervisis, N. G.},
   title = {High-frequency irreversible electroporation brain tumor ablation: exploring the dynamics of cell death and recovery},
   journal = {Bioelectrochemistry},
   volume = {144},
   pages = {108001},
   note = {1878-562x
Murphy, Kelsey R
Aycock, Kenneth N
Hay, Alayna N
Rossmeisl, John H
Davalos, Rafael V
Dervisis, Nikolaos G
R01 CA213423/CA/NCI NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Netherlands
2021/11/30
Bioelectrochemistry. 2022 Apr;144:108001. doi: 10.1016/j.bioelechem.2021.108001. Epub 2021 Nov 17.},
   abstract = {Improved therapeutics for malignant brain tumors are urgently needed. High-frequency irreversible electroporation (H-FIRE) is a minimally invasive, nonthermal tissue ablation technique, which utilizes high-frequency, bipolar electric pulses to precisely kill tumor cells. The mechanisms of H-FIRE-induced tumor cell death and potential for cellular recovery are incompletely characterized. We hypothesized that tumor cells treated with specific H-FIRE electric field doses can survive and retain proliferative capacity. F98 glioma and LL/2 Lewis lung carcinoma cell suspensions were treated with H-FIRE to model primary and metastatic brain cancer, respectively. Cell membrane permeability, apoptosis, metabolic viability, and proliferative capacity were temporally measured using exclusion dyes, condensed chromatin staining, WST-8 fluorescence, and clonogenic assays, respectively. Both tumor cell lines exhibited dose-dependent permeabilization, with 1,500 V/cm permitting and 3,000 V/cm inhibiting membrane recovery 24 h post-treatment. Cells treated with 1,500 V/cm demonstrated significant and progressive recovery of apoptosis and metabolic activity, in contrast to cells treated with higher H-FIRE doses. Cancer cells treated with recovery-permitting doses of H-FIRE maintained while those treated with recovery-inhibiting doses lost proliferative capacity. Taken together, our data suggest that H-FIRE induces reversible and irreversible cellular damage in a dose-dependent manner, and the presence of dose-dependent recovery mechanisms permits tumor cell proliferation.},
   keywords = {*Brain Neoplasms
Apoptosis
Brain cancer
Cell death
High-frequency irreversible electroporation
Proliferation
Recovery},
   ISSN = {1567-5394 (Print)
1567-5394},
   DOI = {10.1016/j.bioelechem.2021.108001},
   year = {2022},
   type = {Journal Article}
}

Improved therapeutics for malignant brain tumors are urgently needed. High-frequency irreversible electroporation (H-FIRE) is a minimally invasive, nonthermal tissue ablation technique, which utilizes high-frequency, bipolar electric pulses to precisely kill tumor cells. The mechanisms of H-FIRE-induced tumor cell death and potential for cellular recovery are incompletely characterized. We hypothesized that tumor cells treated with specific H-FIRE electric field doses can survive and retain proliferative capacity. F98 glioma and LL/2 Lewis lung carcinoma cell suspensions were treated with H-FIRE to model primary and metastatic brain cancer, respectively. Cell membrane permeability, apoptosis, metabolic viability, and proliferative capacity were temporally measured using exclusion dyes, condensed chromatin staining, WST-8 fluorescence, and clonogenic assays, respectively. Both tumor cell lines exhibited dose-dependent permeabilization, with 1,500 V/cm permitting and 3,000 V/cm inhibiting membrane recovery 24 h post-treatment. Cells treated with 1,500 V/cm demonstrated significant and progressive recovery of apoptosis and metabolic activity, in contrast to cells treated with higher H-FIRE doses. Cancer cells treated with recovery-permitting doses of H-FIRE maintained while those treated with recovery-inhibiting doses lost proliferative capacity. Taken together, our data suggest that H-FIRE induces reversible and irreversible cellular damage in a dose-dependent manner, and the presence of dose-dependent recovery mechanisms permits tumor cell proliferation.

@article{RN100,
   author = {Partridge, B. and Eardley, A. and Morales, B. E. and Campelo, S. N. and Lorenzo, M. F. and Mehta, J. N. and Kani, Y. and Mora, J. K. G. and Campbell, E. Y. and Arena, C. B. and Platt, S. and Mintz, A. and Shinn, R. L. and Rylander, C. G. and Debinski, W. and Davalos, R. V. and Rossmeisl, J. H.},
   title = {Advancements in drug delivery methods for the treatment of brain disease},
   journal = {Front Vet Sci},
   volume = {9},
   pages = {1039745},
   note = {2297-1769
Partridge, Brittanie
Eardley, Allison
Morales, Brianna E
Campelo, Sabrina N
Lorenzo, Melvin F
Mehta, Jason N
Kani, Yukitaka
Mora, Josefa K Garcia
Campbell, Etse-Oghena Y
Arena, Christopher B
Platt, Simon
Mintz, Akiva
Shinn, Richard L
Rylander, Christopher G
Debinski, Waldemar
Davalos, Rafael V
Rossmeisl, John H
P01 CA207206/CA/NCI NIH HHS/United States
T32 EB007507/EB/NIBIB NIH HHS/United States
Journal Article
Review
Switzerland
2022/11/05
Front Vet Sci. 2022 Oct 18;9:1039745. doi: 10.3389/fvets.2022.1039745. eCollection 2022.},
   abstract = {The blood-brain barrier (BBB) presents a formidable obstacle to the effective delivery of systemically administered pharmacological agents to the brain, with ~5% of candidate drugs capable of effectively penetrating the BBB. A variety of biomaterials and therapeutic delivery devices have recently been developed that facilitate drug delivery to the brain. These technologies have addressed many of the limitations imposed by the BBB by: (1) designing or modifying the physiochemical properties of therapeutic compounds to allow for transport across the BBB; (2) bypassing the BBB by administration of drugs via alternative routes; and (3) transiently disrupting the BBB (BBBD) using biophysical therapies. Here we specifically review colloidal drug carrier delivery systems, intranasal, intrathecal, and direct interstitial drug delivery methods, focused ultrasound BBBD, and pulsed electrical field induced BBBD, as well as the key features of BBB structure and function that are the mechanistic targets of these approaches. Each of these drug delivery technologies are illustrated in the context of their potential clinical applications and limitations in companion animals with naturally occurring intracranial diseases.},
   keywords = {blood-brain barrier
brain tumors
convection enhanced delivery
focused ultrasound
interstitial delivery
nanoparticles
pulsed electric fields},
   ISSN = {2297-1769 (Print)
2297-1769},
   DOI = {10.3389/fvets.2022.1039745},
   year = {2022},
   type = {Journal Article}
}

The blood-brain barrier (BBB) presents a formidable obstacle to the effective delivery of systemically administered pharmacological agents to the brain, with  5% of candidate drugs capable of effectively penetrating the BBB. A variety of biomaterials and therapeutic delivery devices have recently been developed that facilitate drug delivery to the brain. These technologies have addressed many of the limitations imposed by the BBB by: (1) designing or modifying the physiochemical properties of therapeutic compounds to allow for transport across the BBB; (2) bypassing the BBB by administration of drugs via alternative routes; and (3) transiently disrupting the BBB (BBBD) using biophysical therapies. Here we specifically review colloidal drug carrier delivery systems, intranasal, intrathecal, and direct interstitial drug delivery methods, focused ultrasound BBBD, and pulsed electrical field induced BBBD, as well as the key features of BBB structure and function that are the mechanistic targets of these approaches. Each of these drug delivery technologies are illustrated in the context of their potential clinical applications and limitations in companion animals with naturally occurring intracranial diseases.

@article{RN105,
   author = {Partridge, B. R. and Kani, Y. and Lorenzo, M. F. and Campelo, S. N. and Allen, I. C. and Hinckley, J. and Hsu, F. C. and Verbridge, S. S. and Robertson, J. L. and Davalos, R. V. and Rossmeisl, J. H.},
   title = {High-Frequency Irreversible Electroporation (H-FIRE) Induced Blood-Brain Barrier Disruption Is Mediated by Cytoskeletal Remodeling and Changes in Tight Junction Protein Regulation},
   journal = {Biomedicines},
   volume = {10},
   number = {6},
   note = {2227-9059
Partridge, Brittanie R
Kani, Yukitaka
Orcid: 0000-0002-7611-2741
Lorenzo, Melvin F
Orcid: 0000-0002-6518-5398
Campelo, Sabrina N
Orcid: 0000-0001-6570-7427
Allen, Irving C
Hinckley, Jonathan
Orcid: 0000-0001-9868-1163
Hsu, Fang-Chi
Verbridge, Scott S
Robertson, John L
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Rossmeisl, John H
Orcid: 0000-0003-1655-7076
P01 CA207206/CA/NCI NIH HHS/United States
P30CA012197/CA/NCI NIH HHS/United States
P01207206/NH/NIH HHS/United States
R01CA213423/CA/NCI NIH HHS/United States
Journal Article
Switzerland
2022/06/25
Biomedicines. 2022 Jun 11;10(6):1384. doi: 10.3390/biomedicines10061384.},
   abstract = {Glioblastoma is the deadliest malignant brain tumor. Its location behind the blood-brain barrier (BBB) presents a therapeutic challenge by preventing effective delivery of most chemotherapeutics. H-FIRE is a novel tumor ablation method that transiently disrupts the BBB through currently unknown mechanisms. We hypothesized that H-FIRE mediated BBB disruption (BBBD) occurs via cytoskeletal remodeling and alterations in tight junction (TJ) protein regulation. Intracranial H-FIRE was delivered to Fischer rats prior to sacrifice at 1-, 24-, 48-, 72-, and 96 h post-treatment. Cytoskeletal proteins and native and ubiquitinated TJ proteins (TJP) were evaluated using immunoprecipitation, Western blotting, and gene-expression arrays on treated and sham control brain lysates. Cytoskeletal and TJ protein expression were further evaluated with immunofluorescent microscopy. A decrease in the F/G-actin ratio, decreased TJP concentrations, and increased ubiquitination of TJP were observed 1-48 h post-H-FIRE compared to sham controls. By 72-96 h, cytoskeletal and TJP expression recovered to pretreatment levels, temporally corresponding with increased claudin-5 and zonula occludens-1 gene expression. Ingenuity pathway analysis revealed significant dysregulation of claudin genes, centered around claudin-6 in H-FIRE treated rats. In conclusion, H-FIRE is capable of permeating the BBB in a spatiotemporal manner via cytoskeletal-mediated TJP modulation. This minimally invasive technology presents with applications for localized and long-lived enhanced intracranial drug delivery.},
   keywords = {blood–brain barrier
glioma
high-frequency irreversible electroporation (H-FIRE)
intracranial drug delivery},
   ISSN = {2227-9059 (Print)
2227-9059},
   DOI = {10.3390/biomedicines10061384},
   year = {2022},
   type = {Journal Article}
}

Glioblastoma is the deadliest malignant brain tumor. Its location behind the blood-brain barrier (BBB) presents a therapeutic challenge by preventing effective delivery of most chemotherapeutics. H-FIRE is a novel tumor ablation method that transiently disrupts the BBB through currently unknown mechanisms. We hypothesized that H-FIRE mediated BBB disruption (BBBD) occurs via cytoskeletal remodeling and alterations in tight junction (TJ) protein regulation. Intracranial H-FIRE was delivered to Fischer rats prior to sacrifice at 1-, 24-, 48-, 72-, and 96 h post-treatment. Cytoskeletal proteins and native and ubiquitinated TJ proteins (TJP) were evaluated using immunoprecipitation, Western blotting, and gene-expression arrays on treated and sham control brain lysates. Cytoskeletal and TJ protein expression were further evaluated with immunofluorescent microscopy. A decrease in the F/G-actin ratio, decreased TJP concentrations, and increased ubiquitination of TJP were observed 1-48 h post-H-FIRE compared to sham controls. By 72-96 h, cytoskeletal and TJP expression recovered to pretreatment levels, temporally corresponding with increased claudin-5 and zonula occludens-1 gene expression. Ingenuity pathway analysis revealed significant dysregulation of claudin genes, centered around claudin-6 in H-FIRE treated rats. In conclusion, H-FIRE is capable of permeating the BBB in a spatiotemporal manner via cytoskeletal-mediated TJP modulation. This minimally invasive technology presents with applications for localized and long-lived enhanced intracranial drug delivery.

@article{RN108,
   author = {Zhao, Y. and McKillop, I. H. and Davalos, R. V.},
   title = {Modeling of a single bipolar electrode with tines for irreversible electroporation delivery},
   journal = {Comput Biol Med},
   volume = {142},
   pages = {104870},
   note = {1879-0534
Zhao, Yajun
McKillop, Iain H
Davalos, Rafael V
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2022/01/21
Comput Biol Med. 2022 Mar;142:104870. doi: 10.1016/j.compbiomed.2021.104870. Epub 2021 Sep 14.},
   abstract = {Irreversible electroporation (IRE) is a non-thermal tumor ablation technology employed to treat solid tumors not amenable to resection or thermal ablation. The IRE systems currently in clinical use deliver electrical pulses via multiple monopolar electrodes. This approach can present significant technical challenges due to the requirement for accurate placement of multiple electrodes and maintenance of parallel electrode alignment during pulse delivery. In this study, we sought to evaluate a novel IRE electrode configuration consisting of a single bipolar electrode with deployable tines. Using commercial finite element software predicted ablation outcomes, thermal damage, ablation sphericity, and energy delivery were calculated for existing monopolar and bipolar electrodes, and bipolar electrodes with either 4 or 8 deployable tines. The bipolar electrodes with tines generated larger predicted ablations compared to existing monopolar (>100%) and bipolar (>10%) arrangements, and the ablation shape using bipolar electrodes with tines were more spherical than those modeled for bipolar electrodes. Thermal damage modeled for bipolar electrodes and bipolar electrodes with tines was less than that of monopolar electrodes (using identical pulse parameters), and bipolar electrodes with tines delivered less energy than monopolar or bipolar electrodes. These studies using a single point of device insertion suggest the potential for developing alternative IRE delivery techniques, and may simplify clinical use and increase the predicted ablation shape/volume.},
   keywords = {Electrodes
*Electroporation/methods
Irreversible electroporation (IRE)
Non-thermal ablation
Single needle insertion
Spherical ablation},
   ISSN = {0010-4825 (Print)
0010-4825},
   DOI = {10.1016/j.compbiomed.2021.104870},
   year = {2022},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a non-thermal tumor ablation technology employed to treat solid tumors not amenable to resection or thermal ablation. The IRE systems currently in clinical use deliver electrical pulses via multiple monopolar electrodes. This approach can present significant technical challenges due to the requirement for accurate placement of multiple electrodes and maintenance of parallel electrode alignment during pulse delivery. In this study, we sought to evaluate a novel IRE electrode configuration consisting of a single bipolar electrode with deployable tines. Using commercial finite element software predicted ablation outcomes, thermal damage, ablation sphericity, and energy delivery were calculated for existing monopolar and bipolar electrodes, and bipolar electrodes with either 4 or 8 deployable tines. The bipolar electrodes with tines generated larger predicted ablations compared to existing monopolar (>100%) and bipolar (>10%) arrangements, and the ablation shape using bipolar electrodes with tines were more spherical than those modeled for bipolar electrodes. Thermal damage modeled for bipolar electrodes and bipolar electrodes with tines was less than that of monopolar electrodes (using identical pulse parameters), and bipolar electrodes with tines delivered less energy than monopolar or bipolar electrodes. These studies using a single point of device insertion suggest the potential for developing alternative IRE delivery techniques, and may simplify clinical use and increase the predicted ablation shape/volume.

@article{RN117,
   author = {Alinezhadbalalami, N. and Graybill, P. M. and Imran, K. M. and Verbridge, S. S. and Allen, I. C. and Davalos, R. V.},
   title = {Generation of Tumor-activated T cells Using Electroporation},
   journal = {Bioelectrochemistry},
   volume = {142},
   pages = {107886},
   note = {1878-562x
Alinezhadbalalami, Nastaran
Graybill, Philip M
Imran, Khan Mohammad
Verbridge, Scott S
Allen, Irving C
Davalos, Rafael V
R01 CA213423/CA/NCI NIH HHS/United States
R03 AI151494/AI/NIAID NIH HHS/United States
R21 EB028429/EB/NIBIB NIH HHS/United States
Journal Article
Netherlands
2021/07/25
Bioelectrochemistry. 2021 Dec;142:107886. doi: 10.1016/j.bioelechem.2021.107886. Epub 2021 Jul 13.},
   abstract = {Expansion of cytotoxic T lymphocytes (CTLs) is a crucial step in almost all cancer immunotherapeutic methods. Current techniques for expansion of tumor-reactive CTLs present major limitations. This study introduces a novel method to effectively produce and expand tumor-activated CTLs using high-voltage pulsed electric fields. We hypothesize that utilizing high-voltage pulsed electric fields may be an ideal method to activate and expand CTLs due to their non-thermal celldeath mechanism. Tumor cells were subjected to high-frequency irreversible electroporation (HFIRE) with various electric field magnitudes (1250, 2500 V/cm) and pulse widths (1, 5, and 10 µs), or irreversible electroporation (IRE) at 1250 V/cm. The treated tumor cells were subsequently cocultured with CD4+ and CD8+ T cells along with antigen-presenting cells. We show that tumor-activated CTLs can be produced and expanded when exposed to treated tumor cells. Our results suggest that CTLs are more effectively expanded when pulsed with HFIRE conditions that induce significant cell death (longer pulse widths and higher voltages). Activated CD8+ T cells demonstrate cytotoxicity to untreated tumor cells suggesting effector function of the activated CTLs. The activated CTLs produced with our technique could be used for clinical applications with the goal of targeting and eliminating the tumor.},
   keywords = {Cell Line, Tumor
Electroporation/*methods
Glioblastoma/*pathology
Humans
T-Lymphocytes, Cytotoxic/*cytology
Anti-tumor immunity
Antigen presentation
Cytotoxic T cell
High frequency irreversible electroporation
Irreversible electroporation
T cell Activation},
   ISSN = {1567-5394 (Print)
1567-5394},
   DOI = {10.1016/j.bioelechem.2021.107886},
   year = {2021},
   type = {Journal Article}
}

Expansion of cytotoxic T lymphocytes (CTLs) is a crucial step in almost all cancer immunotherapeutic methods. Current techniques for expansion of tumor-reactive CTLs present major limitations. This study introduces a novel method to effectively produce and expand tumor-activated CTLs using high-voltage pulsed electric fields. We hypothesize that utilizing high-voltage pulsed electric fields may be an ideal method to activate and expand CTLs due to their non-thermal celldeath mechanism. Tumor cells were subjected to high-frequency irreversible electroporation (HFIRE) with various electric field magnitudes (1250, 2500 V/cm) and pulse widths (1, 5, and 10 µs), or irreversible electroporation (IRE) at 1250 V/cm. The treated tumor cells were subsequently cocultured with CD4+ and CD8+ T cells along with antigen-presenting cells. We show that tumor-activated CTLs can be produced and expanded when exposed to treated tumor cells. Our results suggest that CTLs are more effectively expanded when pulsed with HFIRE conditions that induce significant cell death (longer pulse widths and higher voltages). Activated CD8+ T cells demonstrate cytotoxicity to untreated tumor cells suggesting effector function of the activated CTLs. The activated CTLs produced with our technique could be used for clinical applications with the goal of targeting and eliminating the tumor.

@article{RN122,
   author = {Aycock, K. N. and Zhao, Y. and Lorenzo, M. F. and Davalos, R. V.},
   title = {A Theoretical Argument for Extended Interpulse Delays in Therapeutic High-Frequency Irreversible Electroporation Treatments},
   journal = {IEEE Trans Biomed Eng},
   volume = {68},
   number = {6},
   pages = {1999-2010},
   note = {1558-2531
Aycock, Kenneth N
Zhao, Yajun
Lorenzo, Melvin F
Davalos, Rafael V
P01 CA207206/CA/NCI NIH HHS/United States
P30 CA012197/CA/NCI NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
R43 CA233158/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2021/01/06
IEEE Trans Biomed Eng. 2021 Jun;68(6):1999-2010. doi: 10.1109/TBME.2021.3049221. Epub 2021 May 21.},
   abstract = {High-frequency irreversible electroporation (H-FIRE) is a tissue ablation modality employing bursts of electrical pulses in a positive phase-interphase delay (d(1))-negative phase-interpulse delay (d(2)) pattern. Despite accumulating evidence suggesting the significance of these delays, their effects on therapeutic outcomes from clinically-relevant H-FIRE waveforms have not been studied extensively. OBJECTIVE: We sought to determine whether modifications to the delays within H-FIRE bursts could yield a more desirable clinical outcome in terms of ablation volume versus extent of tissue excitation. METHODS: We used a modified spatially extended nonlinear node (SENN) nerve fiber model to evaluate excitation thresholds for H-FIRE bursts with varying delays. We then calculated non-thermal tissue ablation, thermal damage, and excitation in a clinically relevant numerical model. RESULTS: Excitation thresholds were maximized by shortening d(1), and extension of d(2) up to 1,000 μs increased excitation thresholds by at least 60% versus symmetric bursts. In the ablation model, long interpulse delays lowered the effective frequency of burst waveforms, modulating field redistribution and reducing heat production. Finally, we demonstrate mathematically that variable delays allow for increased voltages and larger ablations with similar extents of excitation as symmetric waveforms. CONCLUSION: Interphase and interpulse delays play a significant role in outcomes resulting from H-FIRE treatment. SIGNIFICANCE: Waveforms with short interphase delays (d(1)) and extended interpulse delays (d(2)) may improve therapeutic efficacy of H-FIRE as it emerges as a clinical tissue ablation modality.},
   keywords = {*Electroporation},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/tbme.2021.3049221},
   year = {2021},
   type = {Journal Article}
}

High-frequency irreversible electroporation (H-FIRE) is a tissue ablation modality employing bursts of electrical pulses in a positive phase-interphase delay (d(1))-negative phase-interpulse delay (d(2)) pattern. Despite accumulating evidence suggesting the significance of these delays, their effects on therapeutic outcomes from clinically-relevant H-FIRE waveforms have not been studied extensively. OBJECTIVE: We sought to determine whether modifications to the delays within H-FIRE bursts could yield a more desirable clinical outcome in terms of ablation volume versus extent of tissue excitation. METHODS: We used a modified spatially extended nonlinear node (SENN) nerve fiber model to evaluate excitation thresholds for H-FIRE bursts with varying delays. We then calculated non-thermal tissue ablation, thermal damage, and excitation in a clinically relevant numerical model. RESULTS: Excitation thresholds were maximized by shortening d(1), and extension of d(2) up to 1,000 μs increased excitation thresholds by at least 60% versus symmetric bursts. In the ablation model, long interpulse delays lowered the effective frequency of burst waveforms, modulating field redistribution and reducing heat production. Finally, we demonstrate mathematically that variable delays allow for increased voltages and larger ablations with similar extents of excitation as symmetric waveforms. CONCLUSION: Interphase and interpulse delays play a significant role in outcomes resulting from H-FIRE treatment. SIGNIFICANCE: Waveforms with short interphase delays (d(1)) and extended interpulse delays (d(2)) may improve therapeutic efficacy of H-FIRE as it emerges as a clinical tissue ablation modality.

@article{RN111,
   author = {Beitel-White, N. and Aycock, K. N. and Manuchehrabadi, N. and Zhao, Y. and Imran, K. M. and Coutermarsh-Ott, S. and Allen, I. C. and Lorenzo, M. F. and Davalos, R. V.},
   title = {Properties of tissue within prostate tumors and treatment planning implications for ablation therapies},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2021},
   pages = {1539-1542},
   note = {2694-0604
Beitel-White, Natalie
Aycock, Kenneth N
Manuchehrabadi, Navid
Zhao, Yajun
Imran, Khan Mohammad
Coutermarsh-Ott, Sheryl
Allen, Irving C
Lorenzo, Melvin F
Davalos, Rafael V
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Research Support, Non-U.S. Gov't
United States
2021/12/12
Annu Int Conf IEEE Eng Med Biol Soc. 2021 Nov;2021:1539-1542. doi: 10.1109/EMBC46164.2021.9630534.},
   abstract = {Irreversible electroporation (IRE) is a promising alternative therapy for the local treatment of prostate tumors. The procedure involves the direct insertion of needle electrodes into the target zone, and subsequent delivery of short but high-voltage pulses. Successful outcomes rely on adequate exposure of the tumor to a threshold electrical field. To aid in predicting this exposure, computational models have been developed, yet often do not incorporate the appropriate tissue-specific properties. This work aims to quantify electrical conductivity behavior during IRE for three types of tissue present in the target area of a prostate cancer ablation: the tumor tissue itself, the surrounding healthy tissue, and potential areas of necrosis within the tumor. Animal tissues were used as a stand-in for primary samples. The patient-derived prostate tumor tissue showed very similar responses to healthy porcine prostate tissue. An examination of necrotic tissue inside the tumors revealed a large difference, however, and a computational model showed that a necrotic core with differing electrical properties can cause unexpected inhomogeneities within the treatment region.},
   keywords = {Animals
Electric Conductivity
Electrodes
*Electroporation
Humans
Male
Prostate/surgery
*Prostatic Neoplasms/therapy
Swine},
   ISSN = {2375-7477},
   DOI = {10.1109/embc46164.2021.9630534},
   year = {2021},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a promising alternative therapy for the local treatment of prostate tumors. The procedure involves the direct insertion of needle electrodes into the target zone, and subsequent delivery of short but high-voltage pulses. Successful outcomes rely on adequate exposure of the tumor to a threshold electrical field. To aid in predicting this exposure, computational models have been developed, yet often do not incorporate the appropriate tissue-specific properties. This work aims to quantify electrical conductivity behavior during IRE for three types of tissue present in the target area of a prostate cancer ablation: the tumor tissue itself, the surrounding healthy tissue, and potential areas of necrosis within the tumor. Animal tissues were used as a stand-in for primary samples. The patient-derived prostate tumor tissue showed very similar responses to healthy porcine prostate tissue. An examination of necrotic tissue inside the tumors revealed a large difference, however, and a computational model showed that a necrotic core with differing electrical properties can cause unexpected inhomogeneities within the treatment region.

@article{RN129,
   author = {Beitel-White, N. and Lorenzo, M. F. and Zhao, Y. and Brock, R. M. and Coutermarsh-Ott, S. and Allen, I. C. and Manuchehrabadi, N. and Davalos, R. V.},
   title = {Multi-Tissue Analysis on the Impact of Electroporation on Electrical and Thermal Properties},
   journal = {IEEE Trans Biomed Eng},
   volume = {68},
   number = {3},
   pages = {771-782},
   note = {1558-2531
Beitel-White, Natalie
Lorenzo, Melvin F
Zhao, Yajun
Brock, Rebecca M
Coutermarsh-Ott, Sheryl
Allen, Irving C
Manuchehrabadi, Navid
Davalos, Rafael V
P01 CA207206/CA/NCI NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2020/08/04
IEEE Trans Biomed Eng. 2021 Mar;68(3):771-782. doi: 10.1109/TBME.2020.3013572. Epub 2021 Feb 18.},
   abstract = {OBJECTIVE: Tissue electroporation is achieved by applying a series of electric pulses to destabilize cell membranes within the target tissue. The treatment volume is dictated by the electric field distribution, which depends on the pulse parameters and tissue type and can be readily predicted using numerical methods. These models require the relevant tissue properties to be known beforehand. This study aims to quantify electrical and thermal properties for three different tissue types relevant to current clinical electroporation. METHODS: Pancreatic, brain, and liver tissue were harvested from pigs, then treated with IRE pulses in a parallel-plate configuration. Resulting current and temperature readings were used to calculate the conductivity and its temperature dependence for each tissue type. Finally, a computational model was constructed to examine the impact of differences between tissue types. RESULTS: Baseline conductivity values (mean 0.11, 0.14, and 0.12 S/m) and temperature coefficients of conductivity (mean 2.0, 2.3, and 1.2 % per degree Celsius) were calculated for pancreas, brain, and liver, respectively. The accompanying computational models suggest field distribution and thermal damage volumes are dependent on tissue type. CONCLUSION: The three tissue types show similar electrical and thermal responses to IRE, though brain tissue exhibits the greatest differences. The results also show that tissue type plays a role in the expected ablation and thermal damage volumes. SIGNIFICANCE: The conductivity and its changes due to heating are expected to have a marked impact on the ablation volume. Incorporating these tissue properties aids in the prediction and optimization of electroporation-based therapies.},
   keywords = {Animals
Electric Conductivity
*Electricity
*Electroporation
Liver
Swine
Temperature},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/tbme.2020.3013572},
   year = {2021},
   type = {Journal Article}
}

OBJECTIVE: Tissue electroporation is achieved by applying a series of electric pulses to destabilize cell membranes within the target tissue. The treatment volume is dictated by the electric field distribution, which depends on the pulse parameters and tissue type and can be readily predicted using numerical methods. These models require the relevant tissue properties to be known beforehand. This study aims to quantify electrical and thermal properties for three different tissue types relevant to current clinical electroporation. METHODS: Pancreatic, brain, and liver tissue were harvested from pigs, then treated with IRE pulses in a parallel-plate configuration. Resulting current and temperature readings were used to calculate the conductivity and its temperature dependence for each tissue type. Finally, a computational model was constructed to examine the impact of differences between tissue types. RESULTS: Baseline conductivity values (mean 0.11, 0.14, and 0.12 S/m) and temperature coefficients of conductivity (mean 2.0, 2.3, and 1.2 % per degree Celsius) were calculated for pancreas, brain, and liver, respectively. The accompanying computational models suggest field distribution and thermal damage volumes are dependent on tissue type. CONCLUSION: The three tissue types show similar electrical and thermal responses to IRE, though brain tissue exhibits the greatest differences. The results also show that tissue type plays a role in the expected ablation and thermal damage volumes. SIGNIFICANCE: The conductivity and its changes due to heating are expected to have a marked impact on the ablation volume. Incorporating these tissue properties aids in the prediction and optimization of electroporation-based therapies.

@article{RN121,
   author = {Chatterjee, K. and Graybill, P. M. and Socha, J. J. and Davalos, R. V. and Staples, A. E.},
   title = {Frequency-specific, valveless flow control in insect-mimetic microfluidic devices},
   journal = {Bioinspir Biomim},
   volume = {16},
   number = {3},
   note = {1748-3190
Chatterjee, Krishnashis
Orcid: 0000-0001-8758-638x
Graybill, Philip M
Socha, John J
Davalos, Rafael V
Staples, Anne E
Orcid: 0000-0003-4823-8184
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
England
2021/02/10
Bioinspir Biomim. 2021 Mar 19;16(3). doi: 10.1088/1748-3190/abe4bc.},
   abstract = {Inexpensive, portable lab-on-a-chip devices would revolutionize fields like environmental monitoring and global health, but current microfluidic chips are tethered to extensive off-chip hardware. Insects, however, are self-contained and expertly manipulate fluids at the microscale using largely unexplored methods. We fabricated a series of microfluidic devices that mimic key features of insect respiratory kinematics observed by synchrotron-radiation imaging, including the collapse of portions of multiple respiratory tracts in response to a single fluctuating pressure signal. In one single-channel device, the flow rate and direction could be controlled by the actuation frequency alone, without the use of internal valves. Additionally, we fabricated multichannel chips whose individual channels responded selectively (on with a variable, frequency-dependent flow rate, or off) to a single, global actuation frequency. Our results demonstrate that insect-mimetic designs have the potential to drastically reduce the actuation overhead for microfluidic chips, and that insect respiratory systems may share features with impedance-mismatch pumps.},
   keywords = {Animals
Biomimetics
Insecta
*Lab-On-A-Chip Devices
*Microfluidics
Physical Phenomena
frequency tuning
insect respiration
microfluidics},
   ISSN = {1748-3182},
   DOI = {10.1088/1748-3190/abe4bc},
   year = {2021},
   type = {Journal Article}
}

Inexpensive, portable lab-on-a-chip devices would revolutionize fields like environmental monitoring and global health, but current microfluidic chips are tethered to extensive off-chip hardware. Insects, however, are self-contained and expertly manipulate fluids at the microscale using largely unexplored methods. We fabricated a series of microfluidic devices that mimic key features of insect respiratory kinematics observed by synchrotron-radiation imaging, including the collapse of portions of multiple respiratory tracts in response to a single fluctuating pressure signal. In one single-channel device, the flow rate and direction could be controlled by the actuation frequency alone, without the use of internal valves. Additionally, we fabricated multichannel chips whose individual channels responded selectively (on with a variable, frequency-dependent flow rate, or off) to a single, global actuation frequency. Our results demonstrate that insect-mimetic designs have the potential to drastically reduce the actuation overhead for microfluidic chips, and that insect respiratory systems may share features with impedance-mismatch pumps.

@article{RN114,
   author = {Duncan, J. L. and Davalos, R. V.},
   title = {A review: Dielectrophoresis for characterizing and separating similar cell subpopulations based on bioelectric property changes due to disease progression and therapy assessment},
   journal = {Electrophoresis},
   volume = {42},
   number = {23},
   pages = {2423-2444},
   note = {1522-2683
Duncan, Josie L
Orcid: 0000-0002-4743-1540
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Journal Article
Research Support, Non-U.S. Gov't
Review
Germany
2021/10/06
Electrophoresis. 2021 Dec;42(23):2423-2444. doi: 10.1002/elps.202100135. Epub 2021 Oct 20.},
   abstract = {This paper reviews the use of dielectrophoresis for high-fidelity separations and characterizations of subpopulations to highlight the recent advances in the electrokinetic field as well as provide insight into its progress toward commercialization. The role of cell subpopulations in heterogeneous clinical samples has been studied to deduce their role in disease progression and therapy resistance for instances such as cancer, tissue regeneration, and bacterial infection. Dielectrophoresis (DEP), a label-free electrokinetic technique, has been used to characterize and separate target subpopulations from mixed samples to determine disease severity, cell stemness, and drug efficacy. Despite its high sensitivity to characterize similar or related cells based on their differing bioelectric signatures, DEP has been slowly adopted both commercially and clinically. This review addresses the use of dielectrophoresis for the identification of target cell subtypes in stem cells, cancer cells, blood cells, and bacterial cells dependent on cell state and therapy exposure and addresses commercialization efforts in light of its sensitivity and future perspectives of the technology, both commercially and academically.},
   keywords = {Animals
Disease Progression
*Electrophoresis/methods
Humans
*Neoplasms/pathology/therapy
Blood cells
Cancer cells
Dielectrophoresis
Stem cells
Subpopulation},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.202100135},
   year = {2021},
   type = {Journal Article}
}

This paper reviews the use of dielectrophoresis for high-fidelity separations and characterizations of subpopulations to highlight the recent advances in the electrokinetic field as well as provide insight into its progress toward commercialization. The role of cell subpopulations in heterogeneous clinical samples has been studied to deduce their role in disease progression and therapy resistance for instances such as cancer, tissue regeneration, and bacterial infection. Dielectrophoresis (DEP), a label-free electrokinetic technique, has been used to characterize and separate target subpopulations from mixed samples to determine disease severity, cell stemness, and drug efficacy. Despite its high sensitivity to characterize similar or related cells based on their differing bioelectric signatures, DEP has been slowly adopted both commercially and clinically. This review addresses the use of dielectrophoresis for the identification of target cell subtypes in stem cells, cancer cells, blood cells, and bacterial cells dependent on cell state and therapy exposure and addresses commercialization efforts in light of its sensitivity and future perspectives of the technology, both commercially and academically.

@article{RN112,
   author = {Graybill, P. M. and Davalos, R. V.},
   title = {A Multiplexed Microfluidic Device to Measure Blood-Brain Barrier Disruption by Pulsed Electric Fields},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2021},
   pages = {1222-1225},
   note = {2694-0604
Graybill, Philip M
Davalos, Rafael V
P01 CA207206/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
United States
2021/12/12
Annu Int Conf IEEE Eng Med Biol Soc. 2021 Nov;2021:1222-1225. doi: 10.1109/EMBC46164.2021.9630078.},
   abstract = {Local disruption of the blood-brain barrier (BBB) by pulsed electric fields shows significant potential for treating neurological conditions. Microfluidic BBB models can provide low-cost, controlled experiments with human cells and test a range of parameters for preclinical studies. We developed a multiplexed BBB device that can test a three-fold range of electric field magnitudes. A tapered channel creates a linear gradient of the electric field within the device, and an asymmetric branching channel enables an on-chip control. We monitored BBB permeability in real-time using the diffusion of a fluorescent marker across an endothelial monolayer to determine BBB disruption after high-frequency bipolar electrical pulses (HFIRE). We show that HFIRE pulses can transiently open the BBB. Unexpectedly, electrofusion of cells resulted in decreased permeability for some conditions. Our multiplexed device can efficiently probe treatment variables for efficient preclinical testing of optimal parameters for reversible BBB disruption.Clinical Relevance-This in vitro model of the BBB can inform preclinical studies by investigating a range of electroporation parameters for BBB disruption.},
   keywords = {*Blood-Brain Barrier
Electroporation
Humans
*Lab-On-A-Chip Devices
Microfluidics
Permeability},
   ISSN = {2375-7477},
   DOI = {10.1109/embc46164.2021.9630078},
   year = {2021},
   type = {Journal Article}
}

Local disruption of the blood-brain barrier (BBB) by pulsed electric fields shows significant potential for treating neurological conditions. Microfluidic BBB models can provide low-cost, controlled experiments with human cells and test a range of parameters for preclinical studies. We developed a multiplexed BBB device that can test a three-fold range of electric field magnitudes. A tapered channel creates a linear gradient of the electric field within the device, and an asymmetric branching channel enables an on-chip control. We monitored BBB permeability in real-time using the diffusion of a fluorescent marker across an endothelial monolayer to determine BBB disruption after high-frequency bipolar electrical pulses (HFIRE). We show that HFIRE pulses can transiently open the BBB. Unexpectedly, electrofusion of cells resulted in decreased permeability for some conditions. Our multiplexed device can efficiently probe treatment variables for efficient preclinical testing of optimal parameters for reversible BBB disruption.Clinical Relevance-This in vitro model of the BBB can inform preclinical studies by investigating a range of electroporation parameters for BBB disruption.

@article{RN123,
   author = {Graybill, P. M. and Jana, A. and Kapania, R. K. and Nain, A. S. and Davalos, R. V.},
   title = {Single Cell Forces after Electroporation},
   journal = {ACS Nano},
   volume = {15},
   number = {2},
   pages = {2554-2568},
   note = {1936-086x
Graybill, Philip M
Orcid: 0000-0002-2057-7478
Jana, Aniket
Orcid: 0000-0003-2830-8210
Kapania, Rakesh K
Nain, Amrinder S
Orcid: 0000-0002-9757-2341
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
P01 CA207206/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
United States
2020/11/26
ACS Nano. 2021 Feb 23;15(2):2554-2568. doi: 10.1021/acsnano.0c07020. Epub 2020 Nov 25.},
   abstract = {Exogenous high-voltage pulses increase cell membrane permeability through a phenomenon known as electroporation. This process may also disrupt the cell cytoskeleton causing changes in cell contractility; however, the contractile signature of cell force after electroporation remains unknown. Here, single-cell forces post-electroporation are measured using suspended extracellular matrix-mimicking nanofibers that act as force sensors. Ten, 100 μs pulses are delivered at three voltage magnitudes (500, 1000, and 1500 V) and two directions (parallel and perpendicular to cell orientation), exposing glioblastoma cells to electric fields between 441 V cm(-1) and 1366 V cm(-1). Cytoskeletal-driven force loss and recovery post-electroporation involves three distinct stages. Low electric field magnitudes do not cause disruption, but higher fields nearly eliminate contractility 2-10 min post-electroporation as cells round following calcium-mediated retraction (stage 1). Following rounding, a majority of analyzed cells enter an unusual and unexpected biphasic stage (stage 2) characterized by increased contractility tens of minutes post-electroporation, followed by force relaxation. The biphasic stage is concurrent with actin disruption-driven blebbing. Finally, cells elongate and regain their pre-electroporation morphology and contractility in 1-3 h (stage 3). With increasing voltages applied perpendicular to cell orientation, we observe a significant drop in cell viability. Experiments with multiple healthy and cancerous cell lines demonstrate that contractile force is a more dynamic and sensitive metric than cell shape to electroporation. A mechanobiological understanding of cell contractility post-electroporation will deepen our understanding of the mechanisms that drive recovery and may have implications for molecular medicine, genetic engineering, and cellular biophysics.},
   keywords = {*Actins/metabolism
Cell Membrane/metabolism
Cell Membrane Permeability
Cell Survival
Cytoskeleton/metabolism
*Electroporation
actin
cytoskeleton
electroporation
forces
mechanobiology
nanofibers
pulsed electric fields},
   ISSN = {1936-0851},
   DOI = {10.1021/acsnano.0c07020},
   year = {2021},
   type = {Journal Article}
}

Exogenous high-voltage pulses increase cell membrane permeability through a phenomenon known as electroporation. This process may also disrupt the cell cytoskeleton causing changes in cell contractility; however, the contractile signature of cell force after electroporation remains unknown. Here, single-cell forces post-electroporation are measured using suspended extracellular matrix-mimicking nanofibers that act as force sensors. Ten, 100 μs pulses are delivered at three voltage magnitudes (500, 1000, and 1500 V) and two directions (parallel and perpendicular to cell orientation), exposing glioblastoma cells to electric fields between 441 V cm(-1) and 1366 V cm(-1). Cytoskeletal-driven force loss and recovery post-electroporation involves three distinct stages. Low electric field magnitudes do not cause disruption, but higher fields nearly eliminate contractility 2-10 min post-electroporation as cells round following calcium-mediated retraction (stage 1). Following rounding, a majority of analyzed cells enter an unusual and unexpected biphasic stage (stage 2) characterized by increased contractility tens of minutes post-electroporation, followed by force relaxation. The biphasic stage is concurrent with actin disruption-driven blebbing. Finally, cells elongate and regain their pre-electroporation morphology and contractility in 1-3 h (stage 3). With increasing voltages applied perpendicular to cell orientation, we observe a significant drop in cell viability. Experiments with multiple healthy and cancerous cell lines demonstrate that contractile force is a more dynamic and sensitive metric than cell shape to electroporation. A mechanobiological understanding of cell contractility post-electroporation will deepen our understanding of the mechanisms that drive recovery and may have implications for molecular medicine, genetic engineering, and cellular biophysics.

@article{RN119,
   author = {Hendricks-Wenger, A. and Aycock, K. N. and Nagai-Singer, M. A. and Coutermarsh-Ott, S. and Lorenzo, M. F. and Gannon, J. and Uh, K. and Farrell, K. and Beitel-White, N. and Brock, R. M. and Simon, A. and Morrison, H. A. and Tuohy, J. and Clark-Deener, S. and Vlaisavljevich, E. and Davalos, R. V. and Lee, K. and Allen, I. C.},
   title = {Establishing an immunocompromised porcine model of human cancer for novel therapy development with pancreatic adenocarcinoma and irreversible electroporation},
   journal = {Sci Rep},
   volume = {11},
   number = {1},
   pages = {7584},
   note = {2045-2322
Hendricks-Wenger, Alissa
Aycock, Kenneth N
Nagai-Singer, Margaret A
Coutermarsh-Ott, Sheryl
Lorenzo, Melvin F
Gannon, Jessica
Uh, Kyungjun
Farrell, Kayla
Beitel-White, Natalie
Brock, Rebecca M
Simon, Alexander
Morrison, Holly A
Tuohy, Joanne
Clark-Deener, Sherrie
Vlaisavljevich, Eli
Davalos, Rafael V
Lee, Kiho
Allen, Irving C
P01 CA207206/CA/NCI NIH HHS/United States
R21 EB028429/EB/NIBIB NIH HHS/United States
R01 CA213423/CA/NCI NIH HHS/United States
R21 OD027062/OD/NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
England
2021/04/09
Sci Rep. 2021 Apr 7;11(1):7584. doi: 10.1038/s41598-021-87228-5.},
   abstract = {New therapies to treat pancreatic cancer are direly needed. However, efficacious interventions lack a strong preclinical model that can recapitulate patients' anatomy and physiology. Likewise, the availability of human primary malignant tissue for ex vivo studies is limited. These are significant limitations in the biomedical device field. We have developed RAG2/IL2RG deficient pigs using CRISPR/Cas9 as a large animal model with the novel application of cancer xenograft studies of human pancreatic adenocarcinoma. In this proof-of-concept study, these pigs were successfully generated using on-demand genetic modifications in embryos, circumventing the need for breeding and husbandry. Human Panc01 cells injected subcutaneously into the ears of RAG2/IL2RG deficient pigs demonstrated 100% engraftment with growth rates similar to those typically observed in mouse models. Histopathology revealed no immune cell infiltration and tumor morphology was highly consistent with the mouse models. The electrical properties and response to irreversible electroporation of the tumor tissue were found to be similar to excised human pancreatic cancer tumors. The ample tumor tissue produced enabled improved accuracy and modeling of the electrical properties of tumor tissue. Together, this suggests that this model will be useful and capable of bridging the gap of translating therapies from the bench to clinical application.},
   keywords = {Adenocarcinoma/pathology/physiopathology/*therapy
Animals
CRISPR-Cas Systems
Cell Line, Tumor
DNA-Binding Proteins/deficiency/genetics/immunology
Electric Conductivity
Electroporation/*methods
Female
Gene Knockout Techniques
Humans
Immunocompromised Host
Interleukin Receptor Common gamma Subunit/deficiency/genetics/immunology
Male
Mice
Pancreatic Neoplasms/pathology/physiopathology/*therapy
Proof of Concept Study
Swine
Translational Research, Biomedical
Xenograft Model Antitumor Assays},
   ISSN = {2045-2322},
   DOI = {10.1038/s41598-021-87228-5},
   year = {2021},
   type = {Journal Article}
}

New therapies to treat pancreatic cancer are direly needed. However, efficacious interventions lack a strong preclinical model that can recapitulate patients' anatomy and physiology. Likewise, the availability of human primary malignant tissue for ex vivo studies is limited. These are significant limitations in the biomedical device field. We have developed RAG2/IL2RG deficient pigs using CRISPR/Cas9 as a large animal model with the novel application of cancer xenograft studies of human pancreatic adenocarcinoma. In this proof-of-concept study, these pigs were successfully generated using on-demand genetic modifications in embryos, circumventing the need for breeding and husbandry. Human Panc01 cells injected subcutaneously into the ears of RAG2/IL2RG deficient pigs demonstrated 100% engraftment with growth rates similar to those typically observed in mouse models. Histopathology revealed no immune cell infiltration and tumor morphology was highly consistent with the mouse models. The electrical properties and response to irreversible electroporation of the tumor tissue were found to be similar to excised human pancreatic cancer tumors. The ample tumor tissue produced enabled improved accuracy and modeling of the electrical properties of tumor tissue. Together, this suggests that this model will be useful and capable of bridging the gap of translating therapies from the bench to clinical application.

@article{RN118,
   author = {Hendricks-Wenger, A. and Sereno, J. and Gannon, J. and Zeher, A. and Brock, R. M. and Beitel-White, N. and Simon, A. and Davalos, R. V. and Coutermarsh-Ott, S. and Vlaisavljevich, E. and Allen, I. C.},
   title = {Histotripsy Ablation Alters the Tumor Microenvironment and Promotes Immune System Activation in a Subcutaneous Model of Pancreatic Cancer},
   journal = {IEEE Trans Ultrason Ferroelectr Freq Control},
   volume = {68},
   number = {9},
   pages = {2987-3000},
   note = {1525-8955
Hendricks-Wenger, Alissa
Sereno, Jacqueline
Gannon, Jessica
Zeher, Allison
Brock, Rebecca M
Beitel-White, Natalie
Simon, Alexander
Davalos, Rafael V
Coutermarsh-Ott, Sheryl
Vlaisavljevich, Eli
Allen, Irving Coy
R21 EB028429/EB/NIBIB NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2021/05/07
IEEE Trans Ultrason Ferroelectr Freq Control. 2021 Sep;68(9):2987-3000. doi: 10.1109/TUFFC.2021.3078094. Epub 2021 Aug 27.},
   abstract = {Pancreatic cancer is a significant cause of cancer-related deaths in the United States with an abysmal five-year overall survival rate that is under 9%. Reasons for this mortality include the lack of late-stage treatment options and the immunosuppressive tumor microenvironment. Histotripsy is an ultrasound-guided, noninvasive, nonthermal tumor ablation therapy that mechanically lyses targeted cells. To study the effects of histotripsy on pancreatic cancer, we utilized an in vitro model of pancreatic adenocarcinoma and compared the release of potential antigens following histotripsy treatment to other ablation modalities. Histotripsy was found to release immune-stimulating molecules at magnitudes similar to other nonthermal ablation modalities and superior to thermal ablation modalities, which corresponded to increased innate immune system activation in vivo. In subsequent in vivo studies, murine Pan02 tumors were grown in mice and treated with histotripsy. Flow cytometry and rtPCR were used to determine changes in the tumor microenvironment over time compared to untreated animals. In mice with pancreatic tumors, we observed significantly increased tumor-progression-free and general survival, with increased activation of the innate immune system 24 h posttreatment and decreased tumor-associated immune cell populations within 14 days of treatment. This study demonstrates the feasibility of using histotripsy for pancreatic cancer ablation and provides mechanistic insight into the initial innate immune system activation following treatment. Further work is needed to establish the mechanisms behind the immunomodulation of the tumor microenvironment and immune effects.},
   keywords = {*Adenocarcinoma
Animals
*High-Intensity Focused Ultrasound Ablation
Immune System
Mice
*Pancreatic Neoplasms/therapy
Tumor Microenvironment},
   ISSN = {0885-3010 (Print)
0885-3010},
   DOI = {10.1109/tuffc.2021.3078094},
   year = {2021},
   type = {Journal Article}
}

Pancreatic cancer is a significant cause of cancer-related deaths in the United States with an abysmal five-year overall survival rate that is under 9%. Reasons for this mortality include the lack of late-stage treatment options and the immunosuppressive tumor microenvironment. Histotripsy is an ultrasound-guided, noninvasive, nonthermal tumor ablation therapy that mechanically lyses targeted cells. To study the effects of histotripsy on pancreatic cancer, we utilized an in vitro model of pancreatic adenocarcinoma and compared the release of potential antigens following histotripsy treatment to other ablation modalities. Histotripsy was found to release immune-stimulating molecules at magnitudes similar to other nonthermal ablation modalities and superior to thermal ablation modalities, which corresponded to increased innate immune system activation in vivo. In subsequent in vivo studies, murine Pan02 tumors were grown in mice and treated with histotripsy. Flow cytometry and rtPCR were used to determine changes in the tumor microenvironment over time compared to untreated animals. In mice with pancreatic tumors, we observed significantly increased tumor-progression-free and general survival, with increased activation of the innate immune system 24 h posttreatment and decreased tumor-associated immune cell populations within 14 days of treatment. This study demonstrates the feasibility of using histotripsy for pancreatic cancer ablation and provides mechanistic insight into the initial innate immune system activation following treatment. Further work is needed to establish the mechanisms behind the immunomodulation of the tumor microenvironment and immune effects.

@article{RN120,
   author = {Hyler, A. R. and Hong, D. and Davalos, R. V. and Swami, N. S. and Schmelz, E. M.},
   title = {A novel ultralow conductivity electromanipulation buffer improves cell viability and enhances dielectrophoretic consistency},
   journal = {Electrophoresis},
   volume = {42},
   number = {12-13},
   pages = {1366-1377},
   note = {1522-2683
Hyler, Alexandra R
Orcid: 0000-0002-8698-4455
Hong, Daly
Davalos, Rafael V
Swami, Nathan S
Schmelz, Eva M
R21 CA173092/CA/NCI NIH HHS/United States
Journal Article
Research Support, Non-U.S. Gov't
Germany
2021/03/10
Electrophoresis. 2021 Jul;42(12-13):1366-1377. doi: 10.1002/elps.202000324. Epub 2021 Apr 15.},
   abstract = {Cell separation has become a critical diagnostic, research, and treatment tool for personalized medicine. Despite significant advances in cell separation, most widely used applications require the use of multiple, expensive antibodies to known markers in order to identify subpopulations of cells for separation. Dielectrophoresis (DEP) provides a biophysical separation technique that can target cell subpopulations based on phenotype without labels and return native cells for downstream analysis. One challenge in employing any DEP device is the sample being separated must be transferred into an ultralow conductivity medium, which can be detrimental in retaining cells' native phenotypes for separation. Here, we measured properties of traditional DEP reagents and determined that after just 1-2 h of exposure and subsequent culture, cells' viability was significantly reduced below 50%. We developed and tested a novel buffer (Cyto Buffer) that achieved 6 weeks of stable shelf-life and demonstrated significantly improved viability and physiological properties. We then determined the impact of Cyto Buffer on cells' dielectric properties and morphology and found that cells retained properties more similar to that of their native media. Finally, we vetted Cyto Buffer's usability on a cell separation platform (Cyto R1) to determine combined efficacy for cell separations. Here, more than 80% of cells from different cell lines were recovered and were determined to be >70% viable following exposure to Cyto Buffer, flow stimulation, electromanipulation, and downstream collection and growth. The developed buffer demonstrated improved opportunities for electrical cell manipulation, enrichment, and recovery for next generation cell separations.},
   keywords = {Cell Line
Cell Separation
Cell Survival
Culture Media
*Electric Conductivity
Electrophoresis
Buffer conductivity
Dielectrophoresis
Electromanipulation
Microfluidics},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.202000324},
   year = {2021},
   type = {Journal Article}
}

Cell separation has become a critical diagnostic, research, and treatment tool for personalized medicine. Despite significant advances in cell separation, most widely used applications require the use of multiple, expensive antibodies to known markers in order to identify subpopulations of cells for separation. Dielectrophoresis (DEP) provides a biophysical separation technique that can target cell subpopulations based on phenotype without labels and return native cells for downstream analysis. One challenge in employing any DEP device is the sample being separated must be transferred into an ultralow conductivity medium, which can be detrimental in retaining cells' native phenotypes for separation. Here, we measured properties of traditional DEP reagents and determined that after just 1-2 h of exposure and subsequent culture, cells' viability was significantly reduced below 50%. We developed and tested a novel buffer (Cyto Buffer) that achieved 6 weeks of stable shelf-life and demonstrated significantly improved viability and physiological properties. We then determined the impact of Cyto Buffer on cells' dielectric properties and morphology and found that cells retained properties more similar to that of their native media. Finally, we vetted Cyto Buffer's usability on a cell separation platform (Cyto R1) to determine combined efficacy for cell separations. Here, more than 80% of cells from different cell lines were recovered and were determined to be >70% viable following exposure to Cyto Buffer, flow stimulation, electromanipulation, and downstream collection and growth. The developed buffer demonstrated improved opportunities for electrical cell manipulation, enrichment, and recovery for next generation cell separations.

@article{RN124,
   author = {Liu, H. and Yao, C. and Zhao, Y. and Chen, X. and Dong, S. and Wang, L. and Davalos, R. V.},
   title = {In Vitro Experimental and Numerical Studies on the Preferential Ablation of Chemo-Resistant Tumor Cells Induced by High-Voltage Nanosecond Pulsed Electric Fields},
   journal = {IEEE Trans Biomed Eng},
   volume = {68},
   number = {8},
   pages = {2400-2411},
   note = {1558-2531
Liu, Hongmei
Yao, Chenguo
Zhao, Yajun
Chen, Xiaoling
Dong, Shoulong
Wang, Li
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2020/11/25
IEEE Trans Biomed Eng. 2021 Aug;68(8):2400-2411. doi: 10.1109/TBME.2020.3040337. Epub 2021 Jul 16.},
   abstract = {Chemoresistance causes tumor recurrence and metastasis, resulting in poor clinical outcomes and low survival, and has been considered an obstacle to tumor therapy. The development of novel therapeutic approaches that can effectively kill chemoresistant tumor cells (CRTCs) is therefore critical to overcoming these obstacles. OBJECTIVE: Here, we introduce an emerging physical feature-based therapeutic approach based on nanosecond pulsed electric fields (nsPEFs). The goal of this study is to investigate the effect of nsPEFs on CRTCs. METHODS: The cell viability, ablation effects on a 3D-cultured scaffold, and lethal thresholds of nsPEFs were evaluated according to fluorescence staining assays. RESULTS: nsPEF treatment preferentially affected chemoresistant cells (A549/CDDP) with a higher cell viability inhibition ability/cell death rate, larger ablation area, and lower ablation threshold compared to their respective homologous tumor cells (A549). The experimental and theoretical studies suggested that nsPEFs displayed selective behavior toward intracellular structures. With this selective character, nsPEFs can induce higher electroporation effects (e.g., higher pore number, larger electroporation area, and faster fluorescence dissipation on the nuclear envelope) on CRTCs due to their larger nuclear size and cell membrane capacitance. CONCLUSION: These findings demonstrated that nsPEFs induced preferential ablation of CRTCs over their respective homologous tumor cells. SIGNIFICANCE: This study provides an experimental and theoretical basis for the study of killing CRTCs by electrical treatments and suggests potential applications in the optimization of novel anti-chemoresistance methods.},
   keywords = {Cell Survival
*Electricity
Electroporation
Humans
*Neoplasms/therapy},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2020.3040337},
   year = {2021},
   type = {Journal Article}
}

Chemoresistance causes tumor recurrence and metastasis, resulting in poor clinical outcomes and low survival, and has been considered an obstacle to tumor therapy. The development of novel therapeutic approaches that can effectively kill chemoresistant tumor cells (CRTCs) is therefore critical to overcoming these obstacles. OBJECTIVE: Here, we introduce an emerging physical feature-based therapeutic approach based on nanosecond pulsed electric fields (nsPEFs). The goal of this study is to investigate the effect of nsPEFs on CRTCs. METHODS: The cell viability, ablation effects on a 3D-cultured scaffold, and lethal thresholds of nsPEFs were evaluated according to fluorescence staining assays. RESULTS: nsPEF treatment preferentially affected chemoresistant cells (A549/CDDP) with a higher cell viability inhibition ability/cell death rate, larger ablation area, and lower ablation threshold compared to their respective homologous tumor cells (A549). The experimental and theoretical studies suggested that nsPEFs displayed selective behavior toward intracellular structures. With this selective character, nsPEFs can induce higher electroporation effects (e.g., higher pore number, larger electroporation area, and faster fluorescence dissipation on the nuclear envelope) on CRTCs due to their larger nuclear size and cell membrane capacitance. CONCLUSION: These findings demonstrated that nsPEFs induced preferential ablation of CRTCs over their respective homologous tumor cells. SIGNIFICANCE: This study provides an experimental and theoretical basis for the study of killing CRTCs by electrical treatments and suggests potential applications in the optimization of novel anti-chemoresistance methods.

@article{RN115,
   author = {Liu, H. and Zhao, Y. and Yao, C. and Schmelz, E. M. and Davalos, R. V.},
   title = {Differential effects of nanosecond pulsed electric fields on cells representing progressive ovarian cancer},
   journal = {Bioelectrochemistry},
   volume = {142},
   pages = {107942},
   note = {1878-562x
Liu, Hongmei
Zhao, Yajun
Yao, Chenguo
Schmelz, Eva M
Davalos, Rafael V
Journal Article
Netherlands
2021/09/13
Bioelectrochemistry. 2021 Dec;142:107942. doi: 10.1016/j.bioelechem.2021.107942. Epub 2021 Aug 31.},
   abstract = {Nanosecond pulsed electric fields (nsPEFs) may induce differential effects on tumor cells from different disease stages and could be suitable for treating tumors by preferentially targeting the late-stage/highly aggressive tumor cells. In this study, we investigated the nsPEF responses of mouse ovarian surface epithelial (MOSE) cells representing progressive ovarian cancer from benign to malignant stages and highly aggressive tumor-initiating-like cells. We established the cell-seeded 3D collagen scaffolds cultured with or without Nocodazole (eliminating the influence of cell proliferation on ablation outcome) to observe the ablation effects at 3 h and 24 h after treatment and compared the corresponding thresholds obtained by numerically calculated electric field distribution. The results showed that nsPEFs induced larger ablation areas with lower thresholds as the cell progress from benign, malignant to a highly aggressive phenotype. This differential effect was not affected by the different doubling times of the cells, as apparent by similar ablation induction after a synergistic treatment of nsPEFs and Nocodazole. The result suggests that nsPEFs could induce preferential ablation effects on highly aggressive and malignant ovarian cancer cells than their benign counterparts. This study provides an experimental basis for the research on killing malignant tumor cells via electrical treatments and may have clinical implications for treating tumors and preventing tumor recurrence after treatment.},
   keywords = {Animals
Cell Line, Tumor
Cell Proliferation
Cell Survival
Electrochemotherapy/*methods
Female
Mice
Ovarian Neoplasms/*therapy
Cellular ablation
Electroporation
Nanosecond pulses
Ovarian cancer progression model
Selectivity},
   ISSN = {1567-5394},
   DOI = {10.1016/j.bioelechem.2021.107942},
   year = {2021},
   type = {Journal Article}
}

Nanosecond pulsed electric fields (nsPEFs) may induce differential effects on tumor cells from different disease stages and could be suitable for treating tumors by preferentially targeting the late-stage/highly aggressive tumor cells. In this study, we investigated the nsPEF responses of mouse ovarian surface epithelial (MOSE) cells representing progressive ovarian cancer from benign to malignant stages and highly aggressive tumor-initiating-like cells. We established the cell-seeded 3D collagen scaffolds cultured with or without Nocodazole (eliminating the influence of cell proliferation on ablation outcome) to observe the ablation effects at 3 h and 24 h after treatment and compared the corresponding thresholds obtained by numerically calculated electric field distribution. The results showed that nsPEFs induced larger ablation areas with lower thresholds as the cell progress from benign, malignant to a highly aggressive phenotype. This differential effect was not affected by the different doubling times of the cells, as apparent by similar ablation induction after a synergistic treatment of nsPEFs and Nocodazole. The result suggests that nsPEFs could induce preferential ablation effects on highly aggressive and malignant ovarian cancer cells than their benign counterparts. This study provides an experimental basis for the research on killing malignant tumor cells via electrical treatments and may have clinical implications for treating tumors and preventing tumor recurrence after treatment.

@article{RN125,
   author = {Lorenzo, M. F. and Bhonsle, S. P. and Arena, C. B. and Davalos, R. V.},
   title = {Rapid Impedance Spectroscopy for Monitoring Tissue Impedance, Temperature, and Treatment Outcome During Electroporation-Based Therapies},
   journal = {IEEE Trans Biomed Eng},
   volume = {68},
   number = {5},
   pages = {1536-1546},
   note = {1558-2531
Lorenzo, Melvin F
Bhonsle, Suyashree P
Arena, Christopher B
Davalos, Rafael V
P30 CA012197/CA/NCI NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
P01 CA207206/CA/NCI NIH HHS/United States
R43 CA233158/CA/NCI NIH HHS/United States
R01 CA213423/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2020/11/07
IEEE Trans Biomed Eng. 2021 May;68(5):1536-1546. doi: 10.1109/TBME.2020.3036535. Epub 2021 Apr 21.},
   abstract = {OBJECTIVE: Electroporation-based therapies (EBTs) employ high voltage pulsed electric fields (PEFs) to permeabilize tumor tissue; this results in changes in electrical properties detectable using electrical impedance spectroscopy (EIS). Currently, commercial potentiostats for EIS are limited by impedance spectrum acquisition time (  ∼ 10 s); this timeframe is much larger than pulse periods used with EBTs (  ∼ 1 s). In this study, we utilize rapid EIS techniques to develop a methodology for characterizing electroporation (EP) and thermal effects associated with high-frequency irreversible EP (H-FIRE) in real-time by monitoring inter-burst impedance changes. METHODS: A charge-balanced, bipolar rectangular chirp signal is proposed for rapid EIS. Validation of rapid EIS measurements against a commercial potentiostat was conducted in potato tissue using flat-plate electrodes and thereafter for the measurement of impedance changes throughout IRE treatment. Flat-plate electrodes were then utilized to uniformly heat potato tissue; throughout high-voltage H-FIRE treatment, low-voltage inter-burst impedance measurements were used to continually monitor impedance change and to identify a frequency at which thermal effects are delineated from EP effects. RESULTS: Inter-burst impedance measurements (1.8 kHz - 4.93 MHz) were accomplished at 216 discrete frequencies. Impedance measurements at frequencies above  ∼ 1 MHz served to delineate thermal and EP effects in measured impedance. CONCLUSION: We demonstrate rapid-capture ( 1 s) EIS which enables monitoring of inter-burst impedance in real-time. For the first time, we show impedance analysis at high frequencies can delineate thermal effects from EP effects in measured impedance. SIGNIFICANCE: The proposed waveform demonstrates the potential to perform inter-burst EIS using PEFs compatible with existing pulse generator topologies.},
   keywords = {*Dielectric Spectroscopy
Electric Impedance
*Electroporation
Temperature
Treatment Outcome},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/tbme.2020.3036535},
   year = {2021},
   type = {Journal Article}
}

OBJECTIVE: Electroporation-based therapies (EBTs) employ high voltage pulsed electric fields (PEFs) to permeabilize tumor tissue; this results in changes in electrical properties detectable using electrical impedance spectroscopy (EIS). Currently, commercial potentiostats for EIS are limited by impedance spectrum acquisition time ( ∼ 10 s); this timeframe is much larger than pulse periods used with EBTs ( ∼ 1 s). In this study, we utilize rapid EIS techniques to develop a methodology for characterizing electroporation (EP) and thermal effects associated with high-frequency irreversible EP (H-FIRE) in real-time by monitoring inter-burst impedance changes. METHODS: A charge-balanced, bipolar rectangular chirp signal is proposed for rapid EIS. Validation of rapid EIS measurements against a commercial potentiostat was conducted in potato tissue using flat-plate electrodes and thereafter for the measurement of impedance changes throughout IRE treatment. Flat-plate electrodes were then utilized to uniformly heat potato tissue; throughout high-voltage H-FIRE treatment, low-voltage inter-burst impedance measurements were used to continually monitor impedance change and to identify a frequency at which thermal effects are delineated from EP effects. RESULTS: Inter-burst impedance measurements (1.8 kHz - 4.93 MHz) were accomplished at 216 discrete frequencies. Impedance measurements at frequencies above ∼ 1 MHz served to delineate thermal and EP effects in measured impedance. CONCLUSION: We demonstrate rapid-capture ( 1 s) EIS which enables monitoring of inter-burst impedance in real-time. For the first time, we show impedance analysis at high frequencies can delineate thermal effects from EP effects in measured impedance. SIGNIFICANCE: The proposed waveform demonstrates the potential to perform inter-burst EIS using PEFs compatible with existing pulse generator topologies.

@article{RN110,
   author = {Lorenzo, M. F. and Campelo, S. N. and Arroyo, J. P. and Aycock, K. N. and Hinckley, J. and Arena, C. B. and Rossmeisl, J. H., Jr. and Davalos, R. V.},
   title = {An Investigation for Large Volume, Focal Blood-Brain Barrier Disruption with High-Frequency Pulsed Electric Fields},
   journal = {Pharmaceuticals (Basel)},
   volume = {14},
   number = {12},
   note = {1424-8247
Lorenzo, Melvin F
Orcid: 0000-0002-6518-5398
Campelo, Sabrina N
Orcid: 0000-0001-6570-7427
Arroyo, Julio P
Orcid: 0000-0003-4690-6337
Aycock, Kenneth N
Orcid: 0000-0003-3885-6798
Hinckley, Jonathan
Orcid: 0000-0001-9868-1163
Arena, Christopher B
Orcid: 0000-0002-9380-1194
Rossmeisl, John H Jr
Orcid: 0000-0003-1655-7076
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
P01 CA207206/CA/NCI NIH HHS/United States
R01 CA213423/CA/NCI NIH HHS/United States
R25 GM072767/GM/NIGMS NIH HHS/United States
P01CA207206/NH/NIH HHS/United States
Journal Article
Switzerland
2021/12/29
Pharmaceuticals (Basel). 2021 Dec 20;14(12):1333. doi: 10.3390/ph14121333.},
   abstract = {The treatment of CNS disorders suffers from the inability to deliver large therapeutic agents to the brain parenchyma due to protection from the blood-brain barrier (BBB). Herein, we investigated high-frequency pulsed electric field (HF-PEF) therapy of various pulse widths and interphase delays for BBB disruption while selectively minimizing cell ablation. Eighteen male Fisher rats underwent craniectomy procedures and two blunt-tipped electrodes were advanced into the brain for pulsing. BBB disruption was verified with contrast T1W MRI and pathologically with Evans blue dye. High-frequency irreversible electroporation cell death of healthy rodent astrocytes was investigated in vitro using a collagen hydrogel tissue mimic. Numerical analysis was conducted to determine the electric fields in which BBB disruption and cell ablation occur. Differences between the BBB disruption and ablation thresholds for each waveform are as follows: 2-2-2 μs (1028 V/cm), 5-2-5 μs (721 V/cm), 10-1-10 μs (547 V/cm), 2-5-2 μs (1043 V/cm), and 5-5-5 μs (751 V/cm). These data suggest that HF-PEFs can be fine-tuned to modulate the extent of cell death while maximizing peri-ablative BBB disruption. Furthermore, numerical modeling elucidated the diffuse field gradients of a single-needle grounding pad configuration to favor large-volume BBB disruption, while the monopolar probe configuration is more amenable to ablation and reversible electroporation effects.},
   keywords = {Evans blue dye
Gadolinium
T1-weighted MRI
blood-brain barrier disruption
electroporation
finite element methods
pulsed field ablation
tissue ablation
treatment planning},
   ISSN = {1424-8247 (Print)
1424-8247},
   DOI = {10.3390/ph14121333},
   year = {2021},
   type = {Journal Article}
}

The treatment of CNS disorders suffers from the inability to deliver large therapeutic agents to the brain parenchyma due to protection from the blood-brain barrier (BBB). Herein, we investigated high-frequency pulsed electric field (HF-PEF) therapy of various pulse widths and interphase delays for BBB disruption while selectively minimizing cell ablation. Eighteen male Fisher rats underwent craniectomy procedures and two blunt-tipped electrodes were advanced into the brain for pulsing. BBB disruption was verified with contrast T1W MRI and pathologically with Evans blue dye. High-frequency irreversible electroporation cell death of healthy rodent astrocytes was investigated in vitro using a collagen hydrogel tissue mimic. Numerical analysis was conducted to determine the electric fields in which BBB disruption and cell ablation occur. Differences between the BBB disruption and ablation thresholds for each waveform are as follows: 2-2-2 μs (1028 V/cm), 5-2-5 μs (721 V/cm), 10-1-10 μs (547 V/cm), 2-5-2 μs (1043 V/cm), and 5-5-5 μs (751 V/cm). These data suggest that HF-PEFs can be fine-tuned to modulate the extent of cell death while maximizing peri-ablative BBB disruption. Furthermore, numerical modeling elucidated the diffuse field gradients of a single-needle grounding pad configuration to favor large-volume BBB disruption, while the monopolar probe configuration is more amenable to ablation and reversible electroporation effects.

@article{RN116,
   author = {Moarefian, M. and Davalos, R. V. and Burton, M. D. and Jones, C. N.},
   title = {Electrotaxis-on-Chip to Quantify Neutrophil Migration Towards Electrochemical Gradients},
   journal = {Front Immunol},
   volume = {12},
   pages = {674727},
   note = {1664-3224
Moarefian, Maryam
Davalos, Rafael V
Burton, Michael D
Jones, Caroline N
R25 GM072767/GM/NIGMS NIH HHS/United States
R35 GM133610/GM/NIGMS NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Switzerland
2021/08/24
Front Immunol. 2021 Aug 6;12:674727. doi: 10.3389/fimmu.2021.674727. eCollection 2021.},
   abstract = {Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including wound healing and immune response to injuries to epithelial barriers (e.g. lung pneumocytes). Immune cells are known to migrate towards both chemical (chemotaxis), physical (mechanotaxis) and electric stimuli (electrotaxis). Electrotaxis is the guided migration of cells along electric fields, and has previously been reported in T-cells and cancer cells. However, there remains a need for engineering tools with high spatial and temporal resolution to quantify EF guided migration. Here we report the development of an electrotaxis-on-chip (ETOC) platform that enables the quantification of dHL-60 cell, a model neutrophil-like cell line, migration toward both electrical and chemoattractant gradients. Neutrophils are the most abundant white blood cells and set the stage for the magnitude of the immune response. Therefore, developing engineering tools to direct neutrophil migration patterns has applications in both infectious disease and inflammatory disorders. The ETOC developed in this study has embedded electrodes and four migration zones connected to a central cell-loading chamber with migration channels [10 µm X 10 µm]. This device enables both parallel and competing chemoattractant and electric fields. We use our novel ETOC platform to investigate dHL-60 cell migration in three biologically relevant conditions: 1) in a DC electric field; 2) parallel chemical gradient and electric fields; and 3) perpendicular chemical gradient and electric field. In this study we used differentiated leukemia cancer cells (dHL60 cells), an accepted model for human peripheral blood neutrophils. We first quantified effects of electric field intensities (0.4V/cm-1V/cm) on dHL-60 cell electrotaxis. Our results show optimal migration at 0.6 V/cm. In the second scenario, we tested whether it was possible to increase dHL-60 cell migration to a bacterial signal [N-formylated peptides (fMLP)] by adding a parallel electric field. Our results show that there was significant increase (6-fold increase) in dHL60 migration toward fMLP and cathode of DC electric field (0.6V/cm, n=4, p-value<0.005) vs. fMLP alone. Finally, we evaluated whether we could decrease or re-direct dHL-60 cell migration away from an inflammatory signal [leukotriene B(4) (LTB(4))]. The perpendicular electric field significantly decreased migration (2.9-fold decrease) of dHL60s toward LTB(4)vs. LTB(4) alone. Our microfluidic device enabled us to quantify single-cell electrotaxis velocity (7.9 µm/min ± 3.6). The magnitude and direction of the electric field can be more precisely and quickly changed than most other guidance cues such as chemical cues in clinical investigation. A better understanding of EF guided cell migration will enable the development of new EF-based treatments to precisely direct immune cell migration for wound care, infection, and other inflammatory disorders.},
   keywords = {Cell Line
Cell Movement/*physiology
Chemotaxis
Electricity
Electrochemical Techniques/*methods
Electromagnetic Fields
Humans
Lab-On-A-Chip Devices
Neutrophils/*physiology
Wound Healing
electrotaxis
immunomodulation
microfluidics
migration
neutrophil},
   ISSN = {1664-3224},
   DOI = {10.3389/fimmu.2021.674727},
   year = {2021},
   type = {Journal Article}
}

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including wound healing and immune response to injuries to epithelial barriers (e.g. lung pneumocytes). Immune cells are known to migrate towards both chemical (chemotaxis), physical (mechanotaxis) and electric stimuli (electrotaxis). Electrotaxis is the guided migration of cells along electric fields, and has previously been reported in T-cells and cancer cells. However, there remains a need for engineering tools with high spatial and temporal resolution to quantify EF guided migration. Here we report the development of an electrotaxis-on-chip (ETOC) platform that enables the quantification of dHL-60 cell, a model neutrophil-like cell line, migration toward both electrical and chemoattractant gradients. Neutrophils are the most abundant white blood cells and set the stage for the magnitude of the immune response. Therefore, developing engineering tools to direct neutrophil migration patterns has applications in both infectious disease and inflammatory disorders. The ETOC developed in this study has embedded electrodes and four migration zones connected to a central cell-loading chamber with migration channels [10 µm X 10 µm]. This device enables both parallel and competing chemoattractant and electric fields. We use our novel ETOC platform to investigate dHL-60 cell migration in three biologically relevant conditions: 1) in a DC electric field; 2) parallel chemical gradient and electric fields; and 3) perpendicular chemical gradient and electric field. In this study we used differentiated leukemia cancer cells (dHL60 cells), an accepted model for human peripheral blood neutrophils. We first quantified effects of electric field intensities (0.4V/cm-1V/cm) on dHL-60 cell electrotaxis. Our results show optimal migration at 0.6 V/cm. In the second scenario, we tested whether it was possible to increase dHL-60 cell migration to a bacterial signal [N-formylated peptides (fMLP)] by adding a parallel electric field. Our results show that there was significant increase (6-fold increase) in dHL60 migration toward fMLP and cathode of DC electric field (0.6V/cm, n=4, p-value<0.005) vs. fMLP alone. Finally, we evaluated whether we could decrease or re-direct dHL-60 cell migration away from an inflammatory signal [leukotriene B(4) (LTB(4))]. The perpendicular electric field significantly decreased migration (2.9-fold decrease) of dHL60s toward LTB(4)vs. LTB(4) alone. Our microfluidic device enabled us to quantify single-cell electrotaxis velocity (7.9 µm/min ± 3.6). The magnitude and direction of the electric field can be more precisely and quickly changed than most other guidance cues such as chemical cues in clinical investigation. A better understanding of EF guided cell migration will enable the development of new EF-based treatments to precisely direct immune cell migration for wound care, infection, and other inflammatory disorders.

@article{RN130,
   author = {Brock, R. M. and Beitel-White, N. and Coutermarsh-Ott, S. and Grider, D. J. and Lorenzo, M. F. and Ringel-Scaia, V. M. and Manuchehrabadi, N. and Martin, R. C. G. and Davalos, R. V. and Allen, I. C.},
   title = {Patient Derived Xenografts Expand Human Primary Pancreatic Tumor Tissue Availability for ex vivo Irreversible Electroporation Testing},
   journal = {Front Oncol},
   volume = {10},
   pages = {843},
   note = {2234-943x
Brock, Rebecca M
Beitel-White, Natalie
Coutermarsh-Ott, Sheryl
Grider, Douglas J
Lorenzo, Melvin F
Ringel-Scaia, Veronica M
Manuchehrabadi, Navid
Martin, Robert C G
Davalos, Rafael V
Allen, Irving C
R21 EB028429/EB/NIBIB NIH HHS/United States
Journal Article
Switzerland
2020/06/13
Front Oncol. 2020 May 22;10:843. doi: 10.3389/fonc.2020.00843. eCollection 2020.},
   abstract = {New methods of tumor ablation have shown exciting efficacy in pre-clinical models but often demonstrate limited success in the clinic. Due to a lack of quality or quantity in primary malignant tissue specimens, therapeutic development and optimization studies are typically conducted on healthy tissue or cell-line derived rodent tumors that don't allow for high resolution modeling of mechanical, chemical, and biological properties. These surrogates do not accurately recapitulate many critical components of the tumor microenvironment that can impact in situ treatment success. Here, we propose utilizing patient-derived xenograft (PDX) models to propagate clinically relevant tumor specimens for the optimization and development of novel tumor ablation modalities. Specimens from three individual pancreatic ductal adenocarcinoma (PDAC) patients were utilized to generate PDX models. This process generated 15-18 tumors that were allowed to expand to 1.5 cm in diameter over the course of 50-70 days. The PDX tumors were morphologically and pathologically identical to primary tumor tissue. Likewise, the PDX tumors were also found to be physiologically superior to other in vitro and ex vivo models based on immortalized cell lines. We utilized the PDX tumors to refine and optimize irreversible electroporation (IRE) treatment parameters. IRE, a novel, non-thermal tumor ablation modality, is being evaluated in a diverse range of cancer clinical trials including pancreatic cancer. The PDX tumors were compared against either Pan02 mouse derived tumors or resected tissue from human PDAC patients. The PDX tumors demonstrated similar changes in electrical conductivity and Joule heating following IRE treatment. Computational modeling revealed a high similarity in the predicted ablation size of the PDX tumors that closely correlate with the data generated with the primary human pancreatic tumor tissue. Gene expression analysis revealed that IRE treatment resulted in an increase in biological pathway signaling associated with interferon gamma signaling, necrosis and mitochondria dysfunction, suggesting potential co-therapy targets. Together, these findings highlight the utility of the PDX system in tumor ablation modeling for IRE and increasing clinical application efficacy. It is also feasible that the use of PDX models will significantly benefit other ablation modality testing beyond IRE.},
   keywords = {Ire
Pdx
ablation
conductivity
inflammation
irreversible electroporation
pancreatic cancer},
   ISSN = {2234-943X (Print)
2234-943x},
   DOI = {10.3389/fonc.2020.00843},
   year = {2020},
   type = {Journal Article}
}

New methods of tumor ablation have shown exciting efficacy in pre-clinical models but often demonstrate limited success in the clinic. Due to a lack of quality or quantity in primary malignant tissue specimens, therapeutic development and optimization studies are typically conducted on healthy tissue or cell-line derived rodent tumors that don't allow for high resolution modeling of mechanical, chemical, and biological properties. These surrogates do not accurately recapitulate many critical components of the tumor microenvironment that can impact in situ treatment success. Here, we propose utilizing patient-derived xenograft (PDX) models to propagate clinically relevant tumor specimens for the optimization and development of novel tumor ablation modalities. Specimens from three individual pancreatic ductal adenocarcinoma (PDAC) patients were utilized to generate PDX models. This process generated 15-18 tumors that were allowed to expand to 1.5 cm in diameter over the course of 50-70 days. The PDX tumors were morphologically and pathologically identical to primary tumor tissue. Likewise, the PDX tumors were also found to be physiologically superior to other in vitro and ex vivo models based on immortalized cell lines. We utilized the PDX tumors to refine and optimize irreversible electroporation (IRE) treatment parameters. IRE, a novel, non-thermal tumor ablation modality, is being evaluated in a diverse range of cancer clinical trials including pancreatic cancer. The PDX tumors were compared against either Pan02 mouse derived tumors or resected tissue from human PDAC patients. The PDX tumors demonstrated similar changes in electrical conductivity and Joule heating following IRE treatment. Computational modeling revealed a high similarity in the predicted ablation size of the PDX tumors that closely correlate with the data generated with the primary human pancreatic tumor tissue. Gene expression analysis revealed that IRE treatment resulted in an increase in biological pathway signaling associated with interferon gamma signaling, necrosis and mitochondria dysfunction, suggesting potential co-therapy targets. Together, these findings highlight the utility of the PDX system in tumor ablation modeling for IRE and increasing clinical application efficacy. It is also feasible that the use of PDX models will significantly benefit other ablation modality testing beyond IRE.

@article{RN127,
   author = {Brock, R. M. and Beitel-White, N. and Davalos, R. V. and Allen, I. C.},
   title = {Starting a Fire Without Flame: The Induction of Cell Death and Inflammation in Electroporation-Based Tumor Ablation Strategies},
   journal = {Front Oncol},
   volume = {10},
   pages = {1235},
   note = {2234-943x
Brock, Rebecca M
Beitel-White, Natalie
Davalos, Rafael V
Allen, Irving C
Journal Article
Review
Switzerland
2020/08/28
Front Oncol. 2020 Jul 28;10:1235. doi: 10.3389/fonc.2020.01235. eCollection 2020.},
   abstract = {New therapeutic strategies and paradigms are direly needed for the treatment of cancer. While the surgical removal of tumors is favored in most cancer treatment plans, resection options are often limited based on tumor localization. Over the last two decades, multiple tumor ablation strategies have emerged as promising stand-alone or combination therapeutic options for patients. These strategies are often employed to treat tumors in areas where surgical resection is not possible or where chemotherapeutics have proven ineffective. The type of cell death induced by the ablation modality is a critical aspect of therapeutic success that can impact the efficacy of the treatment and systemic anti-tumor immune system responses. Electroporation-based ablation technologies include electrochemotherapy, irreversible electroporation, and other modalities that rely on pulsed electric fields to create pores in cell membranes. These pores can either be reversible or irreversible depending on the electric field parameters and can induce cell death either alone or in combination with a therapeutic agent. However, there have been many controversial findings among these technologies as to the cell death type initiated, from apoptosis to pyroptosis. As cell death mechanisms can impact treatment side effects and efficacy, we review the main types of cell death induced by electroporation-based treatments and summarize the impact of these mechanisms on treatment response. We also discuss potential reasons behind the variability of findings such as the similarities between cell death pathways, differences between cell-types, and the variation in electric field strength across the treatment area.},
   keywords = {ablation
apoptosis
calcium
cancer
electroporation
necrosis
pyroptosis},
   ISSN = {2234-943X (Print)
2234-943x},
   DOI = {10.3389/fonc.2020.01235},
   year = {2020},
   type = {Journal Article}
}

New therapeutic strategies and paradigms are direly needed for the treatment of cancer. While the surgical removal of tumors is favored in most cancer treatment plans, resection options are often limited based on tumor localization. Over the last two decades, multiple tumor ablation strategies have emerged as promising stand-alone or combination therapeutic options for patients. These strategies are often employed to treat tumors in areas where surgical resection is not possible or where chemotherapeutics have proven ineffective. The type of cell death induced by the ablation modality is a critical aspect of therapeutic success that can impact the efficacy of the treatment and systemic anti-tumor immune system responses. Electroporation-based ablation technologies include electrochemotherapy, irreversible electroporation, and other modalities that rely on pulsed electric fields to create pores in cell membranes. These pores can either be reversible or irreversible depending on the electric field parameters and can induce cell death either alone or in combination with a therapeutic agent. However, there have been many controversial findings among these technologies as to the cell death type initiated, from apoptosis to pyroptosis. As cell death mechanisms can impact treatment side effects and efficacy, we review the main types of cell death induced by electroporation-based treatments and summarize the impact of these mechanisms on treatment response. We also discuss potential reasons behind the variability of findings such as the similarities between cell death pathways, differences between cell-types, and the variation in electric field strength across the treatment area.

@article{RN141,
   author = {DeWitt, M. R. and Latouche, E. L. and Kaufman, J. D. and Fesmire, C. C. and Swet, J. H. and Kirks, R. C. and Baker, E. H. and Vrochides, D. and Iannitti, D. A. and McKillop, I. H. and Davalos, R. V. and Sano, M. B.},
   title = {Simplified Non-Thermal Tissue Ablation With a Single Insertion Device Enabled by Bipolar High-Frequency Pulses},
   journal = {IEEE Trans Biomed Eng},
   volume = {67},
   number = {7},
   pages = {2043-2051},
   note = {1558-2531
DeWitt, Matthew R
Latouche, Eduardo L
Kaufman, Jacob D
Fesmire, Christopher C
Swet, Jacob H
Kirks, Russel C
Baker, Erin H
Vrochides, Dionisios
Iannitti, David A
McKillop, Iain H
Davalos, Rafael V
Sano, Michael B
Journal Article
Research Support, Non-U.S. Gov't
United States
2019/11/22
IEEE Trans Biomed Eng. 2020 Jul;67(7):2043-2051. doi: 10.1109/TBME.2019.2954122. Epub 2019 Nov 18.},
   abstract = {OBJECTIVE: To demonstrate the feasibility of a single electrode and grounding pad approach for delivering high frequency irreversible electroporation treatments (H-FIRE) in in-vivo hepatic tissue. METHODS: Ablations were created in porcine liver under surgical anesthesia by adminstereing high frequency bursts of 0.5-5.0 μs pulses with amplitudes between 1.1-1.7 kV in the absence of cardiac synchronization or intraoperative paralytics. Finite element simulations were used to determine the electric field strength associated with the ablation margins (E(Lethal)) and predict the ablations feasible with next generation electronics. RESULTS: All animals survived the procedures for the protocol duration without adverse events. E(Lethal) of 2550, 1650, and 875 V/cm were found for treatments consisting of 100x bursts containing 0.5 μs pulses and 25, 50, and 75 μs of energized-time per burst, respectively. Treatments with 1 μs pulses consisting of 100 bursts with 100 μs energized-time per burst resulted in E(Lethal) of 650 V/cm. CONCLUSION: A single electrode and grounding pad approach was successfully used to create ablations in hepatic tissue. This technique has the potential to reduce challenges associated with placing multiple electrodes in anatomically challenging environments. SIGNIFICANCE: H-FIRE is an in situ tumor ablation approach in which electrodes are placed within or around a targeted region to deliver high voltage electrical pulses. Electric fields generated around the electrodes induce irrecoverable cell membrane damage leading to predictable cell death in the relative absence of thermal damage. The sparing of architectural integrity means H-FIRE offers potential advantages compared to thermal ablation modalities for ablating tumors near critical structures.},
   keywords = {Animals
*Bipolar Disorder
Cell Death
Electrodes
*Electroporation
Liver/surgery
Swine},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2019.2954122},
   year = {2020},
   type = {Journal Article}
}

OBJECTIVE: To demonstrate the feasibility of a single electrode and grounding pad approach for delivering high frequency irreversible electroporation treatments (H-FIRE) in in-vivo hepatic tissue. METHODS: Ablations were created in porcine liver under surgical anesthesia by adminstereing high frequency bursts of 0.5-5.0 μs pulses with amplitudes between 1.1-1.7 kV in the absence of cardiac synchronization or intraoperative paralytics. Finite element simulations were used to determine the electric field strength associated with the ablation margins (E(Lethal)) and predict the ablations feasible with next generation electronics. RESULTS: All animals survived the procedures for the protocol duration without adverse events. E(Lethal) of 2550, 1650, and 875 V/cm were found for treatments consisting of 100x bursts containing 0.5 μs pulses and 25, 50, and 75 μs of energized-time per burst, respectively. Treatments with 1 μs pulses consisting of 100 bursts with 100 μs energized-time per burst resulted in E(Lethal) of 650 V/cm. CONCLUSION: A single electrode and grounding pad approach was successfully used to create ablations in hepatic tissue. This technique has the potential to reduce challenges associated with placing multiple electrodes in anatomically challenging environments. SIGNIFICANCE: H-FIRE is an in situ tumor ablation approach in which electrodes are placed within or around a targeted region to deliver high voltage electrical pulses. Electric fields generated around the electrodes induce irrecoverable cell membrane damage leading to predictable cell death in the relative absence of thermal damage. The sparing of architectural integrity means H-FIRE offers potential advantages compared to thermal ablation modalities for ablating tumors near critical structures.

@article{RN135,
   author = {Geboers, B. and Scheffer, H. J. and Graybill, P. M. and Ruarus, A. H. and Nieuwenhuizen, S. and Puijk, R. S. and van den Tol, P. M. and Davalos, R. V. and Rubinsky, B. and de Gruijl, T. D. and Miklavčič, D. and Meijerink, M. R.},
   title = {High-Voltage Electrical Pulses in Oncology: Irreversible Electroporation, Electrochemotherapy, Gene Electrotransfer, Electrofusion, and Electroimmunotherapy},
   journal = {Radiology},
   volume = {295},
   number = {2},
   pages = {254-272},
   note = {1527-1315
Geboers, Bart
Orcid: 0000-0002-8137-9299
Scheffer, Hester J
Orcid: 0000-0001-6298-383x
Graybill, Philip M
Orcid: 0000-0002-2057-7478
Ruarus, Alette H
Orcid: 0000-0002-0823-6398
Nieuwenhuizen, Sanne
Orcid: 0000-0002-5219-6135
Puijk, Robbert S
Orcid: 0000-0003-3293-4433
van den Tol, Petrousjka M
Orcid: 0000-0002-0206-8741
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Rubinsky, Boris
Orcid: 0000-0002-2794-1543
de Gruijl, Tanja D
Miklavčič, Damijan
Orcid: 0000-0003-3506-9449
Meijerink, Martijn R
Orcid: 0000-0002-1500-7294
Journal Article
Review
United States
2020/03/26
Radiology. 2020 May;295(2):254-272. doi: 10.1148/radiol.2020192190. Epub 2020 Mar 24.},
   abstract = {This review summarizes the use of high-voltage electrical pulses (HVEPs) in clinical oncology to treat solid tumors with irreversible electroporation (IRE) and electrochemotherapy (ECT). HVEPs increase the membrane permeability of cells, a phenomenon known as electroporation. Unlike alternative ablative therapies, electroporation does not affect the structural integrity of surrounding tissue, thereby enabling tumors in the vicinity of vital structures to be treated. IRE uses HVEPs to cause cell death by inducing membrane disruption, and it is primarily used as a radical ablative therapy in the treatment of soft-tissue tumors in the liver, kidney, prostate, and pancreas. ECT uses HVEPs to transiently increase membrane permeability, enhancing cellular cytotoxic drug uptake in tumors. IRE and ECT show immunogenic effects that could be augmented when combined with immunomodulatory drugs, a combination therapy the authors term electroimmunotherapy. Additional electroporation-based technologies that may reach clinical importance, such as gene electrotransfer, electrofusion, and electroimmunotherapy, are concisely reviewed. HVEPs represent a substantial advancement in cancer research, and continued improvement and implementation of these presented technologies will require close collaboration between engineers, interventional radiologists, medical oncologists, and immuno-oncologists.},
   keywords = {Antineoplastic Agents/administration & dosage
Cell Fusion/methods
Electric Stimulation Therapy/methods
Electrochemotherapy/methods
Electroporation/*methods
Gene Transfer Techniques
Humans
Immunotherapy/methods
Medical Oncology/*methods
Neoplasms/*therapy},
   ISSN = {0033-8419},
   DOI = {10.1148/radiol.2020192190},
   year = {2020},
   type = {Journal Article}
}

This review summarizes the use of high-voltage electrical pulses (HVEPs) in clinical oncology to treat solid tumors with irreversible electroporation (IRE) and electrochemotherapy (ECT). HVEPs increase the membrane permeability of cells, a phenomenon known as electroporation. Unlike alternative ablative therapies, electroporation does not affect the structural integrity of surrounding tissue, thereby enabling tumors in the vicinity of vital structures to be treated. IRE uses HVEPs to cause cell death by inducing membrane disruption, and it is primarily used as a radical ablative therapy in the treatment of soft-tissue tumors in the liver, kidney, prostate, and pancreas. ECT uses HVEPs to transiently increase membrane permeability, enhancing cellular cytotoxic drug uptake in tumors. IRE and ECT show immunogenic effects that could be augmented when combined with immunomodulatory drugs, a combination therapy the authors term electroimmunotherapy. Additional electroporation-based technologies that may reach clinical importance, such as gene electrotransfer, electrofusion, and electroimmunotherapy, are concisely reviewed. HVEPs represent a substantial advancement in cancer research, and continued improvement and implementation of these presented technologies will require close collaboration between engineers, interventional radiologists, medical oncologists, and immuno-oncologists.

@article{RN133,
   author = {Graybill, P. M. and Davalos, R. V.},
   title = {Cytoskeletal Disruption after Electroporation and Its Significance to Pulsed Electric Field Therapies},
   journal = {Cancers (Basel)},
   volume = {12},
   number = {5},
   note = {2072-6694
Graybill, Philip M
Orcid: 0000-0002-2057-7478
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
P01 CA207206/CA/NCI NIH HHS/United States
P01CA207206/NH/NIH HHS/United States
Journal Article
Review
Switzerland
2020/05/06
Cancers (Basel). 2020 Apr 30;12(5):1132. doi: 10.3390/cancers12051132.},
   abstract = {Pulsed electric fields (PEFs) have become clinically important through the success of Irreversible Electroporation (IRE), Electrochemotherapy (ECT), and nanosecond PEFs (nsPEFs) for the treatment of tumors. PEFs increase the permeability of cell membranes, a phenomenon known as electroporation. In addition to well-known membrane effects, PEFs can cause profound cytoskeletal disruption. In this review, we summarize the current understanding of cytoskeletal disruption after PEFs. Compiling available studies, we describe PEF-induced cytoskeletal disruption and possible mechanisms of disruption. Additionally, we consider how cytoskeletal alterations contribute to cell-cell and cell-substrate disruption. We conclude with a discussion of cytoskeletal disruption-induced anti-vascular effects of PEFs and consider how a better understanding of cytoskeletal disruption after PEFs may lead to more effective therapies.},
   keywords = {Ect
Ire
actin
cancer
cell junctions
cytoskeleton
electroporation
intermediate filaments
mechanobiology
microtubules
nsPEFs
pulsed electric fields
vascular lock},
   ISSN = {2072-6694 (Print)
2072-6694},
   DOI = {10.3390/cancers12051132},
   year = {2020},
   type = {Journal Article}
}

Pulsed electric fields (PEFs) have become clinically important through the success of Irreversible Electroporation (IRE), Electrochemotherapy (ECT), and nanosecond PEFs (nsPEFs) for the treatment of tumors. PEFs increase the permeability of cell membranes, a phenomenon known as electroporation. In addition to well-known membrane effects, PEFs can cause profound cytoskeletal disruption. In this review, we summarize the current understanding of cytoskeletal disruption after PEFs. Compiling available studies, we describe PEF-induced cytoskeletal disruption and possible mechanisms of disruption. Additionally, we consider how cytoskeletal alterations contribute to cell-cell and cell-substrate disruption. We conclude with a discussion of cytoskeletal disruption-induced anti-vascular effects of PEFs and consider how a better understanding of cytoskeletal disruption after PEFs may lead to more effective therapies.

@article{RN136,
   author = {Mercadal, B. and Beitel-White, N. and Aycock, K. N. and Castellví, Q. and Davalos, R. V. and Ivorra, A.},
   title = {Dynamics of Cell Death After Conventional IRE and H-FIRE Treatments},
   journal = {Ann Biomed Eng},
   volume = {48},
   number = {5},
   pages = {1451-1462},
   note = {1573-9686
Mercadal, Borja
Beitel-White, Natalie
Aycock, Kenneth N
Castellví, Quim
Davalos, Rafael V
Ivorra, Antoni
Orcid: 0000-0001-7718-8767
TEC2014-52383-C3-2-R/Ministerio de Economía y Competitividad/
PUJFSANY/Cures Within Reach/
16-65-IANN/PCAN/Pancreatic Cancer Action Network/United States
Journal Article
United States
2020/02/07
Ann Biomed Eng. 2020 May;48(5):1451-1462. doi: 10.1007/s10439-020-02462-8. Epub 2020 Feb 5.},
   abstract = {High-frequency irreversible electroporation (H-FIRE) has emerged as an alternative to conventional irreversible electroporation (IRE) to overcome the issues associated with neuromuscular electrical stimulation that appear in IRE treatments. In H-FIRE, the monopolar pulses typically used in IRE are replaced with bursts of short bipolar pulses. Currently, very little is known regarding how the use of a different waveform affects the cell death dynamics and mechanisms. In this study, human pancreatic adenocarcinoma cells were treated with a typical IRE protocol and various H-FIRE schemes with the same energized time. Cell viability, membrane integrity and Caspase 3/7 activity were assessed at different times after the treatment. In both treatments, we identified two different death dynamics (immediate and delayed) and we quantified the electric field ranges that lead to each of them. While in the typical IRE protocol, the electric field range leading to a delayed cell death is very narrow, this range is wider in H-FIRE and can be increased by reducing the pulse length. Membrane integrity in cells suffering a delayed cell death shows a similar time evolution in all treatments, however, Caspase 3/7 expression was only observed in cells treated with H-FIRE.},
   keywords = {Caspase 3/metabolism
Caspase 7/metabolism
Cell Culture Techniques
*Cell Death
Cell Line, Tumor
Electroporation/*methods
Humans
Bipolar pulses
Caspase 3/7
High-frequency irreversible electroporation
Irreversible electroporation
Membrane permeability},
   ISSN = {0090-6964 (Print)
0090-6964},
   DOI = {10.1007/s10439-020-02462-8},
   year = {2020},
   type = {Journal Article}
}

High-frequency irreversible electroporation (H-FIRE) has emerged as an alternative to conventional irreversible electroporation (IRE) to overcome the issues associated with neuromuscular electrical stimulation that appear in IRE treatments. In H-FIRE, the monopolar pulses typically used in IRE are replaced with bursts of short bipolar pulses. Currently, very little is known regarding how the use of a different waveform affects the cell death dynamics and mechanisms. In this study, human pancreatic adenocarcinoma cells were treated with a typical IRE protocol and various H-FIRE schemes with the same energized time. Cell viability, membrane integrity and Caspase 3/7 activity were assessed at different times after the treatment. In both treatments, we identified two different death dynamics (immediate and delayed) and we quantified the electric field ranges that lead to each of them. While in the typical IRE protocol, the electric field range leading to a delayed cell death is very narrow, this range is wider in H-FIRE and can be increased by reducing the pulse length. Membrane integrity in cells suffering a delayed cell death shows a similar time evolution in all treatments, however, Caspase 3/7 expression was only observed in cells treated with H-FIRE.

@article{RN126,
   author = {Moarefian, M. and Davalos, R. V. and Tafti, D. K. and Achenie, L. E. and Jones, C. N.},
   title = {Modeling iontophoretic drug delivery in a microfluidic device},
   journal = {Lab Chip},
   volume = {20},
   number = {18},
   pages = {3310-3321},
   note = {1473-0189
Moarefian, Maryam
Davalos, Rafael V
Tafti, Danesh K
Achenie, Luke E
Jones, Caroline N
R25 GM072767/GM/NIGMS NIH HHS/United States
R35 GM133610/GM/NIGMS NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
England
2020/09/02
Lab Chip. 2020 Sep 21;20(18):3310-3321. doi: 10.1039/d0lc00602e. Epub 2020 Sep 1.},
   abstract = {Iontophoresis employs low-intensity electrical voltage and continuous constant current to direct a charged drug into a tissue. Iontophoretic drug delivery has recently been used as a novel method for cancer treatment in vivo. There is an urgent need to precisely model the low-intensity electric fields in cell culture systems to optimize iontophoretic drug delivery to tumors. Here, we present an iontophoresis-on-chip (IOC) platform to precisely quantify carboplatin drug delivery and its corresponding anti-cancer efficacy under various voltages and currents. In this study, we use an in vitro heparin-based hydrogel microfluidic device to model the movement of a charged drug across an extracellular matrix (ECM) and in MDA-MB-231 triple-negative breast cancer (TNBC) cells. Transport of the drug through the hydrogel was modeled based on diffusion and electrophoresis of charged drug molecules in the direction of an oppositely charged electrode. The drug concentration in the tumor extracellular matrix was computed using finite element modeling of transient drug transport in the heparin-based hydrogel. The model predictions were then validated using the IOC platform by comparing the predicted concentration of a fluorescent cationic dye (Alexa Fluor 594®) to the actual concentration in the microfluidic device. Alexa Fluor 594® was used because it has a molecular weight close to paclitaxel, the gold standard drug for treating TNBC, and carboplatin. Our results demonstrated that a 50 mV DC electric field and a 3 mA electrical current significantly increased drug delivery and tumor cell death by 48.12% ± 14.33 and 39.13% ± 12.86, respectively (n = 3, p-value <0.05). The IOC platform and mathematical drug delivery model of iontophoresis are promising tools for precise delivery of chemotherapeutic drugs into solid tumors. Further improvements to the IOC platform can be made by adding a layer of epidermal cells to model the skin.},
   keywords = {Drug Delivery Systems
*Iontophoresis
Lab-On-A-Chip Devices
*Pharmaceutical Preparations/metabolism
Skin/metabolism
Skin Absorption},
   ISSN = {1473-0197 (Print)
1473-0189},
   DOI = {10.1039/d0lc00602e},
   year = {2020},
   type = {Journal Article}
}

Iontophoresis employs low-intensity electrical voltage and continuous constant current to direct a charged drug into a tissue. Iontophoretic drug delivery has recently been used as a novel method for cancer treatment in vivo. There is an urgent need to precisely model the low-intensity electric fields in cell culture systems to optimize iontophoretic drug delivery to tumors. Here, we present an iontophoresis-on-chip (IOC) platform to precisely quantify carboplatin drug delivery and its corresponding anti-cancer efficacy under various voltages and currents. In this study, we use an in vitro heparin-based hydrogel microfluidic device to model the movement of a charged drug across an extracellular matrix (ECM) and in MDA-MB-231 triple-negative breast cancer (TNBC) cells. Transport of the drug through the hydrogel was modeled based on diffusion and electrophoresis of charged drug molecules in the direction of an oppositely charged electrode. The drug concentration in the tumor extracellular matrix was computed using finite element modeling of transient drug transport in the heparin-based hydrogel. The model predictions were then validated using the IOC platform by comparing the predicted concentration of a fluorescent cationic dye (Alexa Fluor 594®) to the actual concentration in the microfluidic device. Alexa Fluor 594® was used because it has a molecular weight close to paclitaxel, the gold standard drug for treating TNBC, and carboplatin. Our results demonstrated that a 50 mV DC electric field and a 3 mA electrical current significantly increased drug delivery and tumor cell death by 48.12% ± 14.33 and 39.13% ± 12.86, respectively (n = 3, p-value <0.05). The IOC platform and mathematical drug delivery model of iontophoresis are promising tools for precise delivery of chemotherapeutic drugs into solid tumors. Further improvements to the IOC platform can be made by adding a layer of epidermal cells to model the skin.

@article{RN137,
   author = {Partridge, B. R. and O'Brien, T. J. and Lorenzo, M. F. and Coutermarsh-Ott, S. L. and Barry, S. L. and Stadler, K. and Muro, N. and Meyerhoeffer, M. and Allen, I. C. and Davalos, R. V. and Dervisis, N. G.},
   title = {High-Frequency Irreversible Electroporation for Treatment of Primary Liver Cancer: A Proof-of-Principle Study in Canine Hepatocellular Carcinoma},
   journal = {J Vasc Interv Radiol},
   volume = {31},
   number = {3},
   pages = {482-491.e4},
   note = {1535-7732
Partridge, Brittanie R
O'Brien, Timothy J
Lorenzo, Melvin F
Coutermarsh-Ott, Sheryl L
Barry, Sabrina L
Stadler, Krystina
Muro, Noelle
Meyerhoeffer, Mitchell
Allen, Irving C
Davalos, Rafael V
Dervisis, Nikolaos G
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
United States
2020/01/21
J Vasc Interv Radiol. 2020 Mar;31(3):482-491.e4. doi: 10.1016/j.jvir.2019.10.015. Epub 2020 Jan 16.},
   abstract = {PURPOSE: To determine the safety and feasibility of percutaneous high-frequency irreversible electroporation (HFIRE) for primary liver cancer and evaluate the HFIRE-induced local immune response. MATERIALS AND METHODS: HFIRE therapy was delivered percutaneously in 3 canine patients with resectable hepatocellular carcinoma (HCC) in the absence of intraoperative paralytic agents or cardiac synchronization. Pre- and post-HFIRE biopsy samples were processed with histopathology and immunohistochemistry for CD3, CD4, CD8, and CD79a. Blood was collected on days 0, 2, and 4 for complete blood count and chemistry. Numeric models were developed to determine the treatment-specific lethal thresholds for malignant canine liver tissue and healthy porcine liver tissue. RESULTS: HFIRE resulted in predictable ablation volumes as assessed by posttreatment CT. No detectable cardiac interference and minimal muscle contraction occurred during HFIRE. No clinically significant adverse events occurred secondary to HFIRE. Microscopically, a well-defined ablation zone surrounded by a reactive zone was evident in the majority of samples. This zone was composed primarily of maturing collagen interspersed with CD3(+)/CD4(-)/CD8(-) lymphocytes in a proinflammatory microenvironment. The average ablation volumes for the canine HCC patients and the healthy porcine tissue were 3.89 cm(3) ± 0.74 and 1.56 cm(3) ± 0.16, respectively (P = .03), and the respective average lethal thresholds were 710 V/cm ± 28.2 and 957 V/cm ± 24.4 V/cm (P = .0004). CONCLUSIONS: HFIRE can safely and effectively be delivered percutaneously, results in a predictable ablation volume, and is associated with lymphocytic tumor infiltration. This is the first step toward the use of HFIRE for treatment of unresectable liver tumors.},
   keywords = {Ablation Techniques/*veterinary
Animals
CD3 Complex/immunology
Carcinoma, Hepatocellular/immunology/pathology/surgery/*veterinary
Dog Diseases/immunology/pathology/*surgery
Dogs
Electroporation/*veterinary
Feasibility Studies
Female
Gene Expression Regulation, Neoplastic
Gene Regulatory Networks
Liver Neoplasms/immunology/pathology/surgery/*veterinary
Lymphocytes, Tumor-Infiltrating/immunology
Male
Proof of Concept Study
Sus scrofa},
   ISSN = {1051-0443 (Print)
1051-0443},
   DOI = {10.1016/j.jvir.2019.10.015},
   year = {2020},
   type = {Journal Article}
}

PURPOSE: To determine the safety and feasibility of percutaneous high-frequency irreversible electroporation (HFIRE) for primary liver cancer and evaluate the HFIRE-induced local immune response. MATERIALS AND METHODS: HFIRE therapy was delivered percutaneously in 3 canine patients with resectable hepatocellular carcinoma (HCC) in the absence of intraoperative paralytic agents or cardiac synchronization. Pre- and post-HFIRE biopsy samples were processed with histopathology and immunohistochemistry for CD3, CD4, CD8, and CD79a. Blood was collected on days 0, 2, and 4 for complete blood count and chemistry. Numeric models were developed to determine the treatment-specific lethal thresholds for malignant canine liver tissue and healthy porcine liver tissue. RESULTS: HFIRE resulted in predictable ablation volumes as assessed by posttreatment CT. No detectable cardiac interference and minimal muscle contraction occurred during HFIRE. No clinically significant adverse events occurred secondary to HFIRE. Microscopically, a well-defined ablation zone surrounded by a reactive zone was evident in the majority of samples. This zone was composed primarily of maturing collagen interspersed with CD3(+)/CD4(-)/CD8(-) lymphocytes in a proinflammatory microenvironment. The average ablation volumes for the canine HCC patients and the healthy porcine tissue were 3.89 cm(3) ± 0.74 and 1.56 cm(3) ± 0.16, respectively (P = .03), and the respective average lethal thresholds were 710 V/cm ± 28.2 and 957 V/cm ± 24.4 V/cm (P = .0004). CONCLUSIONS: HFIRE can safely and effectively be delivered percutaneously, results in a predictable ablation volume, and is associated with lymphocytic tumor infiltration. This is the first step toward the use of HFIRE for treatment of unresectable liver tumors.

@article{RN128,
   author = {Perera-Bel, E. and Yagüe, C. and Mercadal, B. and Ceresa, M. and Beitel-White, N. and Davalos, R. V. and Ballester, M. A. G. and Ivorra, A.},
   title = {EView: An electric field visualization web platform for electroporation-based therapies},
   journal = {Comput Methods Programs Biomed},
   volume = {197},
   pages = {105682},
   note = {1872-7565
Perera-Bel, Enric
Yagüe, Carlos
Mercadal, Borja
Ceresa, Mario
Beitel-White, Natalie
Davalos, Rafael V
Ballester, Miguel A González
Ivorra, Antoni
R01 CA213423/CA/NCI NIH HHS/United States
R01 CA240476/CA/NCI NIH HHS/United States
Journal Article
Ireland
2020/08/17
Comput Methods Programs Biomed. 2020 Dec;197:105682. doi: 10.1016/j.cmpb.2020.105682. Epub 2020 Aug 2.},
   abstract = {BACKGROUND AND OBJECTIVES: Electroporation is the phenomenon by which cell membrane permeability to ions and macromolecules is increased when the cell is briefly exposed to high electric fields. In electroporation-based treatments, such exposure is typically performed by delivering high voltage pulses across needle electrodes in tissue. For a given tissue and pulsing protocol, an electric field magnitude threshold exists that must be overreached for treatment efficacy. However, it is hard to preoperatively infer the treatment volume because the electric field distribution intricately depends on the electrodes' positioning and length, the applied voltage, and the electric conductivity of the treated tissues. For illustrating such dependencies, we have created EView (https://eview.upf.edu), a web platform that estimates the electric field distribution for arbitrary needle electrode locations and orientations and overlays it on 3D medical images. METHODS: A client-server approach has been implemented to let the user set the electrode configuration easily on the web browser, whereas the simulation is computed on a dedicated server. By means of the finite element method, the electric field is solved in a 3D volume. For the sake of simplicity, only a homogeneous tissue is modeled, assuming the same properties for healthy and pathologic tissues. The non-linear dependence of tissue conductivity on the electric field due to the electroporation effect is modeled. The implemented model has been validated against a state of the art finite element solver, and the server has undergone a heavy load test to ensure reliability and to report execution times. RESULTS: The electric field is rapidly computed for any electrode and tissue configuration, and alternative setups can be easily compared. The platform provides the same results as the state of the art finite element solver (Dice = 98.3 ± 0.4%). During the high load test, the server remained responsive. Simulations are computed in less than 2 min for simple cases consisting of two electrodes and take up to 40 min for complex scenarios consisting of 6 electrodes. CONCLUSIONS: With this free platform we provide expert and non-expert electroporation users a way to rapidly model the electric field distribution for arbitrary electrode configurations.},
   keywords = {*Computer Simulation
Electric Conductivity
*Electrochemotherapy
Electrodes
*Electroporation
Reproducibility of Results
Electric field visualization
Electrochemotherapy
Electroporation
Irreversible electroporation
Modeling
Simulation
Treatment planning
Web platform},
   ISSN = {0169-2607 (Print)
0169-2607},
   DOI = {10.1016/j.cmpb.2020.105682},
   year = {2020},
   type = {Journal Article}
}

BACKGROUND AND OBJECTIVES: Electroporation is the phenomenon by which cell membrane permeability to ions and macromolecules is increased when the cell is briefly exposed to high electric fields. In electroporation-based treatments, such exposure is typically performed by delivering high voltage pulses across needle electrodes in tissue. For a given tissue and pulsing protocol, an electric field magnitude threshold exists that must be overreached for treatment efficacy. However, it is hard to preoperatively infer the treatment volume because the electric field distribution intricately depends on the electrodes' positioning and length, the applied voltage, and the electric conductivity of the treated tissues. For illustrating such dependencies, we have created EView (https://eview.upf.edu), a web platform that estimates the electric field distribution for arbitrary needle electrode locations and orientations and overlays it on 3D medical images. METHODS: A client-server approach has been implemented to let the user set the electrode configuration easily on the web browser, whereas the simulation is computed on a dedicated server. By means of the finite element method, the electric field is solved in a 3D volume. For the sake of simplicity, only a homogeneous tissue is modeled, assuming the same properties for healthy and pathologic tissues. The non-linear dependence of tissue conductivity on the electric field due to the electroporation effect is modeled. The implemented model has been validated against a state of the art finite element solver, and the server has undergone a heavy load test to ensure reliability and to report execution times. RESULTS: The electric field is rapidly computed for any electrode and tissue configuration, and alternative setups can be easily compared. The platform provides the same results as the state of the art finite element solver (Dice = 98.3 ± 0.4%). During the high load test, the server remained responsive. Simulations are computed in less than 2 min for simple cases consisting of two electrodes and take up to 40 min for complex scenarios consisting of 6 electrodes. CONCLUSIONS: With this free platform we provide expert and non-expert electroporation users a way to rapidly model the electric field distribution for arbitrary electrode configurations.

@article{RN132,
   author = {Salahi, A. and Varhue, W. B. and Farmehini, V. and Hyler, A. R. and Schmelz, E. M. and Davalos, R. V. and Swami, N. S.},
   title = {Self-aligned microfluidic contactless dielectrophoresis device fabricated by single-layer imprinting on cyclic olefin copolymer},
   journal = {Anal Bioanal Chem},
   volume = {412},
   number = {16},
   pages = {3881-3889},
   note = {1618-2650
Salahi, Armita
Varhue, Walter B
Farmehini, Vahid
Hyler, Alexandra R
Schmelz, Eva M
Davalos, Rafael V
Swami, Nathan S
FA2386-18-1-4100/Air Force Office of Scientific Research/
R21 AI130902/AI/NIAID NIH HHS/United States
UL1 TR003015/TR/NCATS NIH HHS/United States
Research Contract/CytoRecovery, Inc./
VBHRC/Virginia Catalyst/
UL1TR003015/TR/NCATS NIH HHS/United States
Journal Article
Germany
2020/05/07
Anal Bioanal Chem. 2020 Jun;412(16):3881-3889. doi: 10.1007/s00216-020-02667-9. Epub 2020 May 5.},
   abstract = {The trapping and deflection of biological cells by dielectrophoresis (DEP) at field non-uniformities in a microfluidic device is often conducted in a contactless dielectrophoresis (cDEP) mode, wherein the electrode channel is in a different layer than the sample channel, so that field penetration through the interceding barrier causes DEP above critical cut-off frequencies. In this manner, through physical separation of the electrode and sample channels, it is possible to spatially modulate electric fields with no electrode-induced damage to biological cells in the sample channel. However, since this device requires interlayer alignment of the electrode to sample channel and needs to maintain a thin interceding barrier (~ 15 μm) over the entire length over which DEP is needed (~ 1 cm), variations in alignment and microstructure fidelity cause wide variations in cDEP trapping level and frequency response across devices. We present a strategy to eliminate interlayer alignment by fabricating self-aligned electrode and sample channels, simultaneously with the interceding barrier layer (14-μm width and 50-μm depth), using a single-layer imprint and bond process on cyclic olefin copolymer. Specifically, by designing support structures, we preserve fidelity of the high aspect ratio insulating posts in the sample channel and the interceding barrier between the sample and electrode channels over the entire device footprint (~ 1 cm). The device operation is validated based on impedance measurements to quantify field penetration through the interceding barrier and by DEP trapping measurements. The presented fabrication strategy can eventually improve cDEP device manufacturing protocols to enable more reproducible DEP performance. Graphical abstract.},
   keywords = {Alkenes/*chemistry
Electrophoresis/*instrumentation
Equipment Design
*Lab-On-A-Chip Devices
Polymers/*chemistry
Dielectrophoresis
Imprint lithography
Microfabrication
Microfluidics
Polymers},
   ISSN = {1618-2642 (Print)
1618-2642},
   DOI = {10.1007/s00216-020-02667-9},
   year = {2020},
   type = {Journal Article}
}

The trapping and deflection of biological cells by dielectrophoresis (DEP) at field non-uniformities in a microfluidic device is often conducted in a contactless dielectrophoresis (cDEP) mode, wherein the electrode channel is in a different layer than the sample channel, so that field penetration through the interceding barrier causes DEP above critical cut-off frequencies. In this manner, through physical separation of the electrode and sample channels, it is possible to spatially modulate electric fields with no electrode-induced damage to biological cells in the sample channel. However, since this device requires interlayer alignment of the electrode to sample channel and needs to maintain a thin interceding barrier (  15 μm) over the entire length over which DEP is needed (  1 cm), variations in alignment and microstructure fidelity cause wide variations in cDEP trapping level and frequency response across devices. We present a strategy to eliminate interlayer alignment by fabricating self-aligned electrode and sample channels, simultaneously with the interceding barrier layer (14-μm width and 50-μm depth), using a single-layer imprint and bond process on cyclic olefin copolymer. Specifically, by designing support structures, we preserve fidelity of the high aspect ratio insulating posts in the sample channel and the interceding barrier between the sample and electrode channels over the entire device footprint (  1 cm). The device operation is validated based on impedance measurements to quantify field penetration through the interceding barrier and by DEP trapping measurements. The presented fabrication strategy can eventually improve cDEP device manufacturing protocols to enable more reproducible DEP performance. Graphical abstract.

@article{RN142,
   author = {Wasson, E. M. and Alinezhadbalalami, N. and Brock, R. M. and Allen, I. C. and Verbridge, S. S. and Davalos, R. V.},
   title = {Understanding the role of calcium-mediated cell death in high-frequency irreversible electroporation},
   journal = {Bioelectrochemistry},
   volume = {131},
   pages = {107369},
   note = {1878-562x
Wasson, Elisa M
Alinezhadbalalami, Nastaran
Brock, Rebecca M
Allen, Irving C
Verbridge, Scott S
Davalos, Rafael V
P01 CA207206/CA/NCI NIH HHS/United States
P30 CA012197/CA/NCI NIH HHS/United States
R01 CA213423/CA/NCI NIH HHS/United States
Journal Article
Netherlands
2019/11/11
Bioelectrochemistry. 2020 Feb;131:107369. doi: 10.1016/j.bioelechem.2019.107369. Epub 2019 Sep 6.},
   abstract = {High-frequency irreversible electroporation (H-FIRE) is an emerging electroporation-based therapy used to ablate cancerous tissue. Treatment consists of delivering short, bipolar pulses (1-10μs) in a series of 80-100 bursts (1 burst/s, 100μs on-time). Reducing pulse duration leads to reduced treatment volumes compared to traditional IRE, therefore larger voltages must be applied to generate ablations comparable in size. We show that adjuvant calcium enhances ablation area in vitro for H-FIRE treatments of several pulse durations (1, 2, 5, 10μs). Furthermore, H-FIRE treatment using 10μs pulses delivered with 1mM CaCl(2) results in cell death thresholds (771±129V/cm) comparable to IRE thresholds without calcium (698±103V/cm). Quantifying the reversible electroporation threshold revealed that CaCl(2) enhances the permeabilization of cells compared to a NaCl control. Gene expression analysis determined that CaCl(2) upregulates expression of eIFB5 and 60S ribosomal subunit genes while downregulating NOX1/4, leading to increased signaling in pathways that may cause necroptosis. The opposite was found for control treatment without CaCl(2) suggesting cells experience an increase in pro survival signaling. Our study is the first to identify key genes and signaling pathways responsible for differences in cell response to H-FIRE treatment with and without calcium.},
   keywords = {Animals
Calcium Chloride/*pharmacology
Cell Death/*drug effects
Cell Line, Tumor
Electroporation/*methods
Humans
Hydrogels
NADPH Oxidases/metabolism
Reactive Oxygen Species/metabolism
Signal Transduction
Calcium
Cell death
Enhanced ablation
High-frequency irreversible electroporation (H-FIRE)
Irreversible electroporation (IRE)
Reversible electroporation},
   ISSN = {1567-5394 (Print)
1567-5394},
   DOI = {10.1016/j.bioelechem.2019.107369},
   year = {2020},
   type = {Journal Article}
}

High-frequency irreversible electroporation (H-FIRE) is an emerging electroporation-based therapy used to ablate cancerous tissue. Treatment consists of delivering short, bipolar pulses (1-10μs) in a series of 80-100 bursts (1 burst/s, 100μs on-time). Reducing pulse duration leads to reduced treatment volumes compared to traditional IRE, therefore larger voltages must be applied to generate ablations comparable in size. We show that adjuvant calcium enhances ablation area in vitro for H-FIRE treatments of several pulse durations (1, 2, 5, 10μs). Furthermore, H-FIRE treatment using 10μs pulses delivered with 1mM CaCl(2) results in cell death thresholds (771±129V/cm) comparable to IRE thresholds without calcium (698±103V/cm). Quantifying the reversible electroporation threshold revealed that CaCl(2) enhances the permeabilization of cells compared to a NaCl control. Gene expression analysis determined that CaCl(2) upregulates expression of eIFB5 and 60S ribosomal subunit genes while downregulating NOX1/4, leading to increased signaling in pathways that may cause necroptosis. The opposite was found for control treatment without CaCl(2) suggesting cells experience an increase in pro survival signaling. Our study is the first to identify key genes and signaling pathways responsible for differences in cell response to H-FIRE treatment with and without calcium.

@article{RN131,
   author = {Zhao, Y. and Zheng, S. and Beitel-White, N. and Liu, H. and Yao, C. and Davalos, R. V.},
   title = {Development of a Multi-Pulse Conductivity Model for Liver Tissue Treated With Pulsed Electric Fields},
   journal = {Front Bioeng Biotechnol},
   volume = {8},
   pages = {396},
   note = {2296-4185
Zhao, Yajun
Zheng, Shuang
Beitel-White, Natalie
Liu, Hongmei
Yao, Chenguo
Davalos, Rafael V
Journal Article
Switzerland
2020/06/09
Front Bioeng Biotechnol. 2020 May 19;8:396. doi: 10.3389/fbioe.2020.00396. eCollection 2020.},
   abstract = {Pulsed electric field treatment modalities typically utilize multiple pulses to permeabilize biological tissue. This electroporation process induces conductivity changes in the tissue, which are indicative of the extent of electroporation. In this study, we characterized the electroporation-induced conductivity changes using all treatment pulses instead of solely the first pulse as in conventional conductivity models. Rabbit liver tissue was employed to study the tissue conductivity changes caused by multiple, 100 μs pulses delivered through flat plate electrodes. Voltage and current data were recorded during treatment and used to calculate the tissue conductivity during the entire pulsing process. Temperature data were also recorded to quantify the contribution of Joule heating to the conductivity according to the tissue temperature coefficient. By fitting all these data to a modified Heaviside function, where the two turning points (E (0), E (1)) and the increase factor (A) are the main parameters, we calculated the conductivity as a function of the electric field (E), where the parameters of the Heaviside function (A and E (0)) were functions of pulse number (N). With the resulting multi-factor conductivity model, a numerical electroporation simulation can predict the electrical current for multiple pulses more accurately than existing conductivity models. Moreover, the saturating behavior caused by electroporation can be explained by the saturation trends of the increase factor A in this model. The conductivity change induced by electroporation has a significant increase at about the first 30 pulses, then tends to saturate at 0.465 S/m. The proposed conductivity model can simulate the electroporation process more accurately than the conventional conductivity model. The electric field distribution computed using this model is essential for treatment planning in biomedical applications utilizing multiple pulsed electric fields, and the method proposed here, relating the pulse number to the conductivity through the variables in the Heaviside function, may be adapted to investigate the effect of other parameters, like pulse frequency and pulse width, on electroporation.},
   keywords = {cumulative effect
dynamic process
electroporation
pulsed electric field
tissue conductivity
treatment planning
tumor ablation},
   ISSN = {2296-4185 (Print)
2296-4185},
   DOI = {10.3389/fbioe.2020.00396},
   year = {2020},
   type = {Journal Article}
}

Pulsed electric field treatment modalities typically utilize multiple pulses to permeabilize biological tissue. This electroporation process induces conductivity changes in the tissue, which are indicative of the extent of electroporation. In this study, we characterized the electroporation-induced conductivity changes using all treatment pulses instead of solely the first pulse as in conventional conductivity models. Rabbit liver tissue was employed to study the tissue conductivity changes caused by multiple, 100 μs pulses delivered through flat plate electrodes. Voltage and current data were recorded during treatment and used to calculate the tissue conductivity during the entire pulsing process. Temperature data were also recorded to quantify the contribution of Joule heating to the conductivity according to the tissue temperature coefficient. By fitting all these data to a modified Heaviside function, where the two turning points (E (0), E (1)) and the increase factor (A) are the main parameters, we calculated the conductivity as a function of the electric field (E), where the parameters of the Heaviside function (A and E (0)) were functions of pulse number (N). With the resulting multi-factor conductivity model, a numerical electroporation simulation can predict the electrical current for multiple pulses more accurately than existing conductivity models. Moreover, the saturating behavior caused by electroporation can be explained by the saturation trends of the increase factor A in this model. The conductivity change induced by electroporation has a significant increase at about the first 30 pulses, then tends to saturate at 0.465 S/m. The proposed conductivity model can simulate the electroporation process more accurately than the conventional conductivity model. The electric field distribution computed using this model is essential for treatment planning in biomedical applications utilizing multiple pulsed electric fields, and the method proposed here, relating the pulse number to the conductivity through the variables in the Heaviside function, may be adapted to investigate the effect of other parameters, like pulse frequency and pulse width, on electroporation.

@article{RN149,
   author = {Alinezhadbalalami, N. and Douglas, T. A. and Balani, N. and Verbridge, S. S. and Davalos, R. V.},
   title = {The feasibility of using dielectrophoresis for isolation of glioblastoma subpopulations with increased stemness},
   journal = {Electrophoresis},
   volume = {40},
   number = {18-19},
   pages = {2592-2600},
   note = {1522-2683
Alinezhadbalalami, Nastaran
Orcid: 0000-0003-2843-361x
Douglas, Temple A
Orcid: 0000-0002-5370-2925
Balani, Nikita
Verbridge, Scott S
Davalos, Rafael V
R01CA213423/NH/NIH HHS/United States
National Institute of Health/International
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Germany
2019/05/28
Electrophoresis. 2019 Sep;40(18-19):2592-2600. doi: 10.1002/elps.201900026. Epub 2019 Jun 6.},
   abstract = {Cancer stem cells (CSCs) are aggressive subpopulations with increased stem-like properties. CSCs are usually resistant to most standard therapies and are responsible for tumor repropagation. Similar to normal stem cells, isolation of CSCs is challenging due to the lack of reliable markers. Antigen-based sorting of CSCs usually requires staining with multiple markers, making the experiments complicated, expensive, and sometimes unreliable. Here, we study the feasibility of using dielectrophoresis (DEP) for isolation of glioblastoma cells with increased stemness. We culture a glioblastoma cell line in the form of neurospheres as an in vitro model for glioblastoma stem cells. We demonstrate that spheroid forming cells have higher expression of stem cell marker, nestin. Next, we show that dielectric properties of neurospheres change as a result of changing culture conditions. Our results indicate that spheroid forming cells need higher voltages to experience the same DEP force magnitude compared to normal monolayer cultures of glioblastoma cell line. This study confirms the possibility of using DEP to isolate glioblastoma stem cells.},
   keywords = {Cell Line, Tumor
Electrophoresis/instrumentation/*methods
Equipment Design
Feasibility Studies
Glioblastoma/*pathology
Humans
Microfluidic Analytical Techniques/instrumentation/*methods
*Spheroids, Cellular/classification/cytology
Tumor Cells, Cultured
Dielectrophoretic
Electrokinetics
Glioblastoma stem cells
Microfluidics
Spheroid culture},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201900026},
   year = {2019},
   type = {Journal Article}
}

Cancer stem cells (CSCs) are aggressive subpopulations with increased stem-like properties. CSCs are usually resistant to most standard therapies and are responsible for tumor repropagation. Similar to normal stem cells, isolation of CSCs is challenging due to the lack of reliable markers. Antigen-based sorting of CSCs usually requires staining with multiple markers, making the experiments complicated, expensive, and sometimes unreliable. Here, we study the feasibility of using dielectrophoresis (DEP) for isolation of glioblastoma cells with increased stemness. We culture a glioblastoma cell line in the form of neurospheres as an in vitro model for glioblastoma stem cells. We demonstrate that spheroid forming cells have higher expression of stem cell marker, nestin. Next, we show that dielectric properties of neurospheres change as a result of changing culture conditions. Our results indicate that spheroid forming cells need higher voltages to experience the same DEP force magnitude compared to normal monolayer cultures of glioblastoma cell line. This study confirms the possibility of using DEP to isolate glioblastoma stem cells.

@article{RN139,
   author = {Aycock, K. N. and Davalos, R. V.},
   title = {Irreversible Electroporation: Background, Theory, and Review of Recent Developments in Clinical Oncology},
   journal = {Bioelectricity},
   volume = {1},
   number = {4},
   pages = {214-234},
   note = {2576-3113
Aycock, Kenneth N
Davalos, Rafael V
Journal Article
Review
United States
2019/12/01
Bioelectricity. 2019 Dec 1;1(4):214-234. doi: 10.1089/bioe.2019.0029. Epub 2019 Dec 12.},
   abstract = {Irreversible electroporation (IRE) has established a clinical niche as an alternative to thermal ablation for the eradication of unresectable tumors, particularly those near critical vascular structures. IRE has been used in over 50 independent clinical trials and has shown clinical success when used as a standalone treatment and as a single component within combinatorial treatment paradigms. Recently, many studies evaluating IRE in larger patient cohorts and alongside other novel therapies have been reported. Here, we present the basic principles of reversible electroporation and IRE followed by a review of preclinical and clinical data with a focus on tumors in three organ systems in which IRE has shown great promise: the prostate, pancreas, and liver. Finally, we discuss alternative and future developments, which will likely further advance the use of IRE in the clinic.},
   keywords = {electroporation
interventional oncology
irreversible electroporation
pulsed electric field},
   ISSN = {2576-3105 (Print)
2576-3105},
   DOI = {10.1089/bioe.2019.0029},
   year = {2019},
   type = {Journal Article}
}

Irreversible electroporation (IRE) has established a clinical niche as an alternative to thermal ablation for the eradication of unresectable tumors, particularly those near critical vascular structures. IRE has been used in over 50 independent clinical trials and has shown clinical success when used as a standalone treatment and as a single component within combinatorial treatment paradigms. Recently, many studies evaluating IRE in larger patient cohorts and alongside other novel therapies have been reported. Here, we present the basic principles of reversible electroporation and IRE followed by a review of preclinical and clinical data with a focus on tumors in three organ systems in which IRE has shown great promise: the prostate, pancreas, and liver. Finally, we discuss alternative and future developments, which will likely further advance the use of IRE in the clinic.

@article{RN138,
   author = {Beitel-White, N. and Martin, R. C. G. and Davalos, R. V.},
   title = {Post-treatment analysis of irreversible electroporation waveforms delivered to human pancreatic cancer patients},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2019},
   pages = {5518-5521},
   note = {2694-0604
Beitel-White, Natalie
Martin, R C G
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2020/01/18
Annu Int Conf IEEE Eng Med Biol Soc. 2019 Jul;2019:5518-5521. doi: 10.1109/EMBC.2019.8857259.},
   abstract = {Irreversible electroporation (IRE) is a focal ablation therapy that uses high voltage, short electrical pulses to destroy tumor tissue. The success of treatment directly depends on exposure of the entire tumor to a lethal electric field magnitude. However, this exposure is difficult to predict ahead of time and it is challenging for clinicians to determine optimal treatment parameters. One method clinicians rely upon for the cessation of pulse delivery is to monitor the resistance value of the tissue, as the cells within the tissue will undergo changes during electroporation. This work presents a computational model which incorporates human pancreatic tumor conductivity, and compares predicted and measured output currents from IRE treatments of human patients. The measured currents vary widely from patient to patient, suggesting there may areas of high local conductivity in the treatment area.},
   keywords = {Computer Simulation
Electric Conductivity
*Electroporation
Humans
*Pancreatic Neoplasms/therapy},
   ISSN = {2375-7477},
   DOI = {10.1109/embc.2019.8857259},
   year = {2019},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a focal ablation therapy that uses high voltage, short electrical pulses to destroy tumor tissue. The success of treatment directly depends on exposure of the entire tumor to a lethal electric field magnitude. However, this exposure is difficult to predict ahead of time and it is challenging for clinicians to determine optimal treatment parameters. One method clinicians rely upon for the cessation of pulse delivery is to monitor the resistance value of the tissue, as the cells within the tissue will undergo changes during electroporation. This work presents a computational model which incorporates human pancreatic tumor conductivity, and compares predicted and measured output currents from IRE treatments of human patients. The measured currents vary widely from patient to patient, suggesting there may areas of high local conductivity in the treatment area.

@article{RN145,
   author = {Byron, C. R. and DeWitt, M. R. and Latouche, E. L. and Davalos, R. V. and Robertson, J. L.},
   title = {Treatment of Infiltrative Superficial Tumors in Awake Standing Horses Using Novel High-Frequency Pulsed Electrical Fields},
   journal = {Front Vet Sci},
   volume = {6},
   pages = {265},
   note = {2297-1769
Byron, Christopher R
DeWitt, Matthew R
Latouche, Eduardo L
Davalos, Rafael V
Robertson, John L
Journal Article
Switzerland
2019/09/03
Front Vet Sci. 2019 Aug 14;6:265. doi: 10.3389/fvets.2019.00265. eCollection 2019.},
   abstract = {Irreversible electroporation is a proven ablation modality for local ablation of soft tissue tumors in animals and humans. However, the strong muscle contractions associated with the electrical impulses (duration, 50-100 μs) requires the use of general anesthesia and, in most situations, application of neuromuscular blockade. As such, this technology is not used in an outpatient setting for ablating common cutaneous tumors (e.g., squamous cell carcinoma or melanoma) in humans or animals. Recently, high-frequency irreversible electroporation (H-FIRE) technology has been developed to enable electroporation of tumors without stimulation of nearby skeletal muscle. H-FIRE administers bursts of electrical pulses (duration, 0.5-2 μs) through bipolar electrodes placed in tumor parenchyma. We hypothesized that H-FIRE could be used to safely ablate superficial tumors in standing, awake horses without the need for general anesthesia. Here, we describe the treatment of superficial tumors in five horses using this novel ablation therapy without the need for general anesthesia. In each case, H-FIRE therapy predictably ablated tumor volume. All patients tolerated the procedure, no complications developed, and veterinary personnel safety was maintained. The H-FIRE treatment may be useful for treatment in veterinary and human patients in an outpatient setting without the need for hospitalization, general anesthesia, and advanced monitoring techniques.},
   keywords = {H-fire
cutaneous tumors
electroporation
focal ablation
horse
models of human disease
non-thermal tumor ablation},
   ISSN = {2297-1769 (Print)
2297-1769},
   DOI = {10.3389/fvets.2019.00265},
   year = {2019},
   type = {Journal Article}
}

Irreversible electroporation is a proven ablation modality for local ablation of soft tissue tumors in animals and humans. However, the strong muscle contractions associated with the electrical impulses (duration, 50-100 μs) requires the use of general anesthesia and, in most situations, application of neuromuscular blockade. As such, this technology is not used in an outpatient setting for ablating common cutaneous tumors (e.g., squamous cell carcinoma or melanoma) in humans or animals. Recently, high-frequency irreversible electroporation (H-FIRE) technology has been developed to enable electroporation of tumors without stimulation of nearby skeletal muscle. H-FIRE administers bursts of electrical pulses (duration, 0.5-2 μs) through bipolar electrodes placed in tumor parenchyma. We hypothesized that H-FIRE could be used to safely ablate superficial tumors in standing, awake horses without the need for general anesthesia. Here, we describe the treatment of superficial tumors in five horses using this novel ablation therapy without the need for general anesthesia. In each case, H-FIRE therapy predictably ablated tumor volume. All patients tolerated the procedure, no complications developed, and veterinary personnel safety was maintained. The H-FIRE treatment may be useful for treatment in veterinary and human patients in an outpatient setting without the need for hospitalization, general anesthesia, and advanced monitoring techniques.

@article{RN134,
   author = {Douglas, T. A. and Alinezhadbalalami, N. and Balani, N. and Schmelz, E. M. and Davalos, R. V.},
   title = {Separation of Macrophages and Fibroblasts Using Contactless Dielectrophoresis and a Novel ImageJ Macro},
   journal = {Bioelectricity},
   volume = {1},
   number = {1},
   pages = {49-55},
   note = {2576-3113
Douglas, Temple Anne
Alinezhadbalalami, Nastaran
Balani, Nikita
Schmelz, Eva M
Davalos, Rafael V
R21 CA173092/CA/NCI NIH HHS/United States
Journal Article
United States
2020/04/16
Bioelectricity. 2019 Mar 1;1(1):49-55. doi: 10.1089/bioe.2018.0004. Epub 2019 Mar 18.},
   abstract = {Background: This study presents a label-free method of separating macrophages and fibroblasts, cell types critically associated with tumors. Materials and Methods: Contactless dielectrophoresis (DEP) devices were used to separate fibroblasts from macrophages by selectively trapping one population. An ImageJ macro was developed to determine the percentage of each population moving or stationary at a given point in time in a video. Results: At 350V(rms), 20 kHz, and 1.25 μL/min, more than 90% of fibroblasts were trapped while less than 20% of macrophages were trapped. Conclusions: Contactless DEP was used to study macrophage and fibroblast separation as a proof-of-concept study for separating cells in the tumor microenvironment. The associated ImageJ macro could be used in other microfluidic cell separation studies.},
   keywords = {cell separation
microenvironment
microfluidics},
   ISSN = {2576-3105 (Print)
2576-3105},
   DOI = {10.1089/bioe.2018.0004},
   year = {2019},
   type = {Journal Article}
}

Background: This study presents a label-free method of separating macrophages and fibroblasts, cell types critically associated with tumors. Materials and Methods: Contactless dielectrophoresis (DEP) devices were used to separate fibroblasts from macrophages by selectively trapping one population. An ImageJ macro was developed to determine the percentage of each population moving or stationary at a given point in time in a video. Results: At 350V(rms), 20 kHz, and 1.25 μL/min, more than 90% of fibroblasts were trapped while less than 20% of macrophages were trapped. Conclusions: Contactless DEP was used to study macrophage and fibroblast separation as a proof-of-concept study for separating cells in the tumor microenvironment. The associated ImageJ macro could be used in other microfluidic cell separation studies.

@article{RN147,
   author = {Heller, R. and Davalos, R. V.},
   title = {Special Collection on Electroporation-Based Therapies: A Selection of Papers From the Second World Congress on Electroporation},
   journal = {Technol Cancer Res Treat},
   volume = {18},
   pages = {1533033819852966},
   note = {1533-0338
Heller, Richard
Orcid: 0000-0003-1899-3859
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Editorial
Introductory Journal Article
United States
2019/05/28
Technol Cancer Res Treat. 2019 Jan-Dec;18:1533033819852966. doi: 10.1177/1533033819852966.},
   keywords = {Electroporation/*methods/standards
Humans
Neoplasms/pathology/*therapy},
   ISSN = {1533-0346 (Print)
1533-0338},
   DOI = {10.1177/1533033819852966},
   year = {2019},
   type = {Journal Article}
}

@article{RN140,
   author = {Lorenzo, M. F. and Thomas, S. C. and Kani, Y. and Hinckley, J. and Lee, M. and Adler, J. and Verbridge, S. S. and Hsu, F. C. and Robertson, J. L. and Davalos, R. V. and Rossmeisl, J. H., Jr.},
   title = {Temporal Characterization of Blood-Brain Barrier Disruption with High-Frequency Electroporation},
   journal = {Cancers (Basel)},
   volume = {11},
   number = {12},
   note = {2072-6694
Lorenzo, Melvin F
Orcid: 0000-0002-6518-5398
Thomas, Sean C
Kani, Yukitaka
Hinckley, Jonathan
Orcid: 0000-0001-9868-1163
Lee, Matthew
Adler, Joy
Verbridge, Scott S
Hsu, Fang-Chi
Robertson, John L
Davalos, Rafael V
Orcid: 0000-0003-1503-9509
Rossmeisl, John H Jr
Orcid: 0000-0003-1655-7076
R01CA213423/NH/NIH HHS/United States
P01CA207206/NH/NIH HHS/United States
Journal Article
Switzerland
2019/11/28
Cancers (Basel). 2019 Nov 23;11(12):1850. doi: 10.3390/cancers11121850.},
   abstract = {Treatment of intracranial disorders suffers from the inability to accumulate therapeutic drug concentrations due to protection from the blood-brain barrier (BBB). Electroporation-based therapies have demonstrated the capability of permeating the BBB, but knowledge of the longevity of BBB disruption (BBBD) is limited. In this study, we quantify the temporal, high-frequency electroporation (HFE)-mediated BBBD in an in vivo healthy rat brain model. 40 male Fisher rats underwent HFE treatment; two blunt tipped monopolar electrodes were advanced into the brain and 200 bursts of HFE were delivered at a voltage-to-distance ratio of 600 V/cm. BBBD was verified with contrast enhanced T1W MRI (gadopentetate dimeglumine) and pathologically (Evans blue dye) at time points of 1, 24, 48, 72, and 96 h after HFE. Contrast enhanced T1W scans demonstrated BBBD for 1 to 72 h after HFE but intact BBB at 96 h. Histologically, tissue damage was restricted to electrode insertion tracks. BBBD was induced with minimal muscle contractions and minimal cell death attributed to HFE. Numerical modeling indicated that brief BBBD was induced with low magnitude electric fields, and BBBD duration increased with field strength. These data suggest the spatiotemporal characteristics of HFE-mediated BBBD may be modulated with the locally applied electric field.},
   keywords = {BBB disruption temporal threshold
Evans blue dye
blood–brain barrier disruption
electric field threshold
electropermeabilization
focal therapy
gadopentetate dimeglumine
high-frequency electroporation
numerical modeling
transient BBB disruption},
   ISSN = {2072-6694 (Print)
2072-6694},
   DOI = {10.3390/cancers11121850},
   year = {2019},
   type = {Journal Article}
}

Treatment of intracranial disorders suffers from the inability to accumulate therapeutic drug concentrations due to protection from the blood-brain barrier (BBB). Electroporation-based therapies have demonstrated the capability of permeating the BBB, but knowledge of the longevity of BBB disruption (BBBD) is limited. In this study, we quantify the temporal, high-frequency electroporation (HFE)-mediated BBBD in an in vivo healthy rat brain model. 40 male Fisher rats underwent HFE treatment; two blunt tipped monopolar electrodes were advanced into the brain and 200 bursts of HFE were delivered at a voltage-to-distance ratio of 600 V/cm. BBBD was verified with contrast enhanced T1W MRI (gadopentetate dimeglumine) and pathologically (Evans blue dye) at time points of 1, 24, 48, 72, and 96 h after HFE. Contrast enhanced T1W scans demonstrated BBBD for 1 to 72 h after HFE but intact BBB at 96 h. Histologically, tissue damage was restricted to electrode insertion tracks. BBBD was induced with minimal muscle contractions and minimal cell death attributed to HFE. Numerical modeling indicated that brief BBBD was induced with low magnitude electric fields, and BBBD duration increased with field strength. These data suggest the spatiotemporal characteristics of HFE-mediated BBBD may be modulated with the locally applied electric field.

@article{RN143,
   author = {O'Brien, T. J. and Lorenzo, M. F. and Zhao, Y. and Neal Ii, R. E. and Robertson, J. L. and Goldberg, S. N. and Davalos, R. V.},
   title = {Cycled pulsing to mitigate thermal damage for multi-electrode irreversible electroporation therapy},
   journal = {Int J Hyperthermia},
   volume = {36},
   number = {1},
   pages = {953-963},
   note = {1464-5157
O'Brien, Timothy J
Lorenzo, Melvin F
Zhao, Yajun
Neal Ii, Robert E
Robertson, John L
Goldberg, S Nahum
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
England
2019/09/24
Int J Hyperthermia. 2019;36(1):953-963. doi: 10.1080/02656736.2019.1657187.},
   abstract = {Purpose: This study evaluates the effects of various pulsing paradigms, on the irreversible electroporation (IRE) lesion, induced electric current, and temperature changes using a perfused porcine liver model. Materials and methods: A 4-monopolar electrode array delivered IRE therapy varying the pulse length and inter-pulse delay to six porcine mechanically perfused livers. Pulse paradigms included six forms of cycled pulsing schemes and the conventional pulsing scheme. Finite element models provided further insight into the effects of cycled pulsing on the temperature and thermal injury distribution. Results: 'Single pulse cycle with no interpulse delay' deposited maximum average energy (2.34 ± 0.35 kJ) and produced the largest ratio of thermally damaged tissue area and IRE ablation area from all other pulse schemes (18.22%  ±  8.11, p < .0001 all pairwise comparisons). These compared favorably to the conventional algorithm (2.09 ± 0.37 kJ, 3.49%  ±  2.20, p < .0001, all comparisons). Though no statistical significance was found between groups, the '5 pulse cycle, 0 s delay' pulse paradigm produced the largest average IRE ablation cross sectional area (11.81 ± 1.97 cm(2)), while conventional paradigm yielded an average of 8.90 ± 0.91 cm(2). Finite element modeling indicated a '10 pulse cycle, 10 s delay' generated the least thermal tissue damage and '1 pulse cycle, 0 s delay' pulse cycle sequence the most (0.47 vs. 3.76 cm(2)), over a lengthier treatment time (16.5 vs. 6.67 minutes). Conclusions: Subdividing IRE pulses and adding delays throughout the treatment can reduce white tissue coagulation and electric current, while maintaining IRE treatment sizes.},
   keywords = {Animals
Electrodes
Electroporation/*methods
Swine
Temperature
Cycled pulsing
irreversible electroporation
perfused organ model
thermal damage
thermal mitigation},
   ISSN = {0265-6736},
   DOI = {10.1080/02656736.2019.1657187},
   year = {2019},
   type = {Journal Article}
}

Purpose: This study evaluates the effects of various pulsing paradigms, on the irreversible electroporation (IRE) lesion, induced electric current, and temperature changes using a perfused porcine liver model. Materials and methods: A 4-monopolar electrode array delivered IRE therapy varying the pulse length and inter-pulse delay to six porcine mechanically perfused livers. Pulse paradigms included six forms of cycled pulsing schemes and the conventional pulsing scheme. Finite element models provided further insight into the effects of cycled pulsing on the temperature and thermal injury distribution. Results: 'Single pulse cycle with no interpulse delay' deposited maximum average energy (2.34 ± 0.35 kJ) and produced the largest ratio of thermally damaged tissue area and IRE ablation area from all other pulse schemes (18.22%  ±  8.11, p < .0001 all pairwise comparisons). These compared favorably to the conventional algorithm (2.09 ± 0.37 kJ, 3.49%  ±  2.20, p < .0001, all comparisons). Though no statistical significance was found between groups, the '5 pulse cycle, 0 s delay' pulse paradigm produced the largest average IRE ablation cross sectional area (11.81 ± 1.97 cm(2)), while conventional paradigm yielded an average of 8.90 ± 0.91 cm(2). Finite element modeling indicated a '10 pulse cycle, 10 s delay' generated the least thermal tissue damage and '1 pulse cycle, 0 s delay' pulse cycle sequence the most (0.47 vs. 3.76 cm(2)), over a lengthier treatment time (16.5 vs. 6.67 minutes). Conclusions: Subdividing IRE pulses and adding delays throughout the treatment can reduce white tissue coagulation and electric current, while maintaining IRE treatment sizes.

@article{RN150,
   author = {O'Brien, T. J. and Passeri, M. and Lorenzo, M. F. and Sulzer, J. K. and Lyman, W. B. and Swet, J. H. and Vrochides, D. and Baker, E. H. and Iannitti, D. A. and Davalos, R. V. and McKillop, I. H.},
   title = {Experimental High-Frequency Irreversible Electroporation Using a Single-Needle Delivery Approach for Nonthermal Pancreatic Ablation In Vivo},
   journal = {J Vasc Interv Radiol},
   volume = {30},
   number = {6},
   pages = {854-862.e7},
   note = {1535-7732
O'Brien, Timothy J
Passeri, Michael
Lorenzo, Melvin F
Sulzer, Jesse K
Lyman, William B
Swet, Jacob H
Vrochides, Dionisios
Baker, Erin H
Iannitti, David A
Davalos, Rafael V
McKillop, Iain H
Journal Article
United States
2019/05/28
J Vasc Interv Radiol. 2019 Jun;30(6):854-862.e7. doi: 10.1016/j.jvir.2019.01.032.},
   abstract = {PURPOSE: To investigate the feasibility of single-needle high-frequency irreversible electroporation (SN-HFIRE) to create reproducible tissue ablations in an in vivo pancreatic swine model. MATERIALS AND METHODS: SN-HFIRE was performed in swine pancreas in vivo in the absence of intraoperative paralytics or cardiac synchronization using 3 different voltage waveforms (1-5-1, 2-5-2, and 5-5-5 [on-off-on times (μs)], n = 6/setting) with a total energized time of 100 μs per burst. At necropsy, ablation size/shape was determined. Immunohistochemistry was performed to quantify apoptosis using an anticleaved caspase-3 antibody. A numerical model was developed to determine lethal thresholds for each waveform in pancreas. RESULTS: Mean tissue ablation time was 5.0 ± 0.2 minutes, and no cardiac abnormalities or muscle twitch was detected. Mean ablation area significantly increased with increasing pulse width (41.0 ± 5.1 mm(2) [range 32-66 mm(2)] vs 44 ± 2.1 mm(2) [range 38-56 mm(2)] vs 85.0 ± 7.0 mm(2) [range 63-155 mm(2)]; 1-5-1, 2-5-2, 5-5-5, respectively; p < 0.0002 5-5-5 vs 1-5-1 and 2-5-2). The majority of the ablation zone did not stain positive for cleaved caspase-3 (6.1 ± 2.8% [range 1.8-9.1%], 8.8 ± 1.3% [range 5.5-14.0%], and 11.0 ± 1.4% [range 7.1-14.2%] cleaved caspase-3 positive 1-5-1, 2-5-2, 5-5-5, respectively), with significantly more positive staining at the 5-5-5 pulse setting compared with 1-5-1 (p < 0.03). Numerical modeling determined a lethal threshold of 1114 ± 123 V/cm (1-5-1 waveform), 1039 ± 103 V/cm (2-5-2 waveform), and 693 ± 81 V/cm (5-5-5 waveform). CONCLUSIONS: SN-HFIRE induces rapid, predictable ablations in pancreatic tissue in vivo without the need for intraoperative paralytics or cardiac synchronization.},
   keywords = {Ablation Techniques/*instrumentation/methods
Animals
Apoptosis
Caspase 3/metabolism
Electroporation/*instrumentation/methods
Feasibility Studies
Female
Finite Element Analysis
Models, Animal
Models, Theoretical
*Needles
Numerical Analysis, Computer-Assisted
Pancreas/metabolism/pathology/*surgery
Sus scrofa},
   ISSN = {1051-0443},
   DOI = {10.1016/j.jvir.2019.01.032},
   year = {2019},
   type = {Journal Article}
}

PURPOSE: To investigate the feasibility of single-needle high-frequency irreversible electroporation (SN-HFIRE) to create reproducible tissue ablations in an in vivo pancreatic swine model. MATERIALS AND METHODS: SN-HFIRE was performed in swine pancreas in vivo in the absence of intraoperative paralytics or cardiac synchronization using 3 different voltage waveforms (1-5-1, 2-5-2, and 5-5-5 [on-off-on times (μs)], n = 6/setting) with a total energized time of 100 μs per burst. At necropsy, ablation size/shape was determined. Immunohistochemistry was performed to quantify apoptosis using an anticleaved caspase-3 antibody. A numerical model was developed to determine lethal thresholds for each waveform in pancreas. RESULTS: Mean tissue ablation time was 5.0 ± 0.2 minutes, and no cardiac abnormalities or muscle twitch was detected. Mean ablation area significantly increased with increasing pulse width (41.0 ± 5.1 mm(2) [range 32-66 mm(2)] vs 44 ± 2.1 mm(2) [range 38-56 mm(2)] vs 85.0 ± 7.0 mm(2) [range 63-155 mm(2)]; 1-5-1, 2-5-2, 5-5-5, respectively; p < 0.0002 5-5-5 vs 1-5-1 and 2-5-2). The majority of the ablation zone did not stain positive for cleaved caspase-3 (6.1 ± 2.8% [range 1.8-9.1%], 8.8 ± 1.3% [range 5.5-14.0%], and 11.0 ± 1.4% [range 7.1-14.2%] cleaved caspase-3 positive 1-5-1, 2-5-2, 5-5-5, respectively), with significantly more positive staining at the 5-5-5 pulse setting compared with 1-5-1 (p < 0.03). Numerical modeling determined a lethal threshold of 1114 ± 123 V/cm (1-5-1 waveform), 1039 ± 103 V/cm (2-5-2 waveform), and 693 ± 81 V/cm (5-5-5 waveform). CONCLUSIONS: SN-HFIRE induces rapid, predictable ablations in pancreatic tissue in vivo without the need for intraoperative paralytics or cardiac synchronization.

@article{RN148,
   author = {Ringel-Scaia, V. M. and Beitel-White, N. and Lorenzo, M. F. and Brock, R. M. and Huie, K. E. and Coutermarsh-Ott, S. and Eden, K. and McDaniel, D. K. and Verbridge, S. S. and Rossmeisl, J. H., Jr. and Oestreich, K. J. and Davalos, R. V. and Allen, I. C.},
   title = {High-frequency irreversible electroporation is an effective tumor ablation strategy that induces immunologic cell death and promotes systemic anti-tumor immunity},
   journal = {EBioMedicine},
   volume = {44},
   pages = {112-125},
   note = {2352-3964
Ringel-Scaia, Veronica M
Beitel-White, Natalie
Lorenzo, Melvin F
Brock, Rebecca M
Huie, Kathleen E
Coutermarsh-Ott, Sheryl
Eden, Kristin
McDaniel, Dylan K
Verbridge, Scott S
Rossmeisl, John H Jr
Oestreich, Kenneth J
Davalos, Rafael V
Allen, Irving C
R01 AI134972/AI/NIAID NIH HHS/United States
R56 AI127800/AI/NIAID NIH HHS/United States
Journal Article
Netherlands
2019/05/28
EBioMedicine. 2019 Jun;44:112-125. doi: 10.1016/j.ebiom.2019.05.036. Epub 2019 May 23.},
   abstract = {BACKGROUND: Despite promising treatments for breast cancer, mortality rates remain high and treatments for metastatic disease are limited. High-frequency irreversible electroporation (H-FIRE) is a novel tumor ablation technique that utilizes high-frequency bipolar electric pulses to destabilize cancer cell membranes and induce cell death. However, there is currently a paucity of data pertaining to immune system activation following H-FIRE and other electroporation based tumor ablation techniques. METHODS: Here, we utilized the mouse 4T1 mammary tumor model to evaluate H-FIRE treatment parameters on cancer progression and immune system activation in vitro and in vivo. FINDINGS: H-FIRE effectively ablates the primary tumor and induces a pro-inflammatory shift in the tumor microenvironment. We further show that local treatment with H-FIRE significantly reduces 4T1 metastases. H-FIRE kills 4T1 cells through non-thermal mechanisms associated with necrosis and pyroptosis resulting in damage associated molecular pattern signaling in vitro and in vivo. Our data indicate that the level of tumor ablation correlates with increased activation of cellular immunity. Likewise, we show that the decrease in metastatic lesions is dependent on the intact immune system and H-FIRE generates 4T1 neoantigens that engage the adaptive immune system to significantly attenuate tumor progression. INTERPRETATION: Cell death and tumor ablation following H-FIRE treatment activates the local innate immune system, which shifts the tumor microenvironment from an anti-inflammatory state to a pro-inflammatory state. The non-thermal damage to the cancer cells and increased innate immune system stimulation improves antigen presentation, resulting in the engagement of the adaptive immune system and improved systemic anti-tumor immunity.},
   keywords = {Animals
*Catheter Ablation/methods
*Cell Death
Computational Biology/methods
Disease Models, Animal
Disease Progression
*Electroporation/methods
Female
Gene Expression Profiling
Gene Regulatory Networks
Humans
Immune System
*Immunomodulation
Mice
Neoplasms/*immunology/metabolism/pathology/therapy
Signal Transduction
Tumor Microenvironment/immunology
Xenograft Model Antitumor Assays
Breast cancer
Ire
Metastasis
Pyroptosis
Tumor microenvironment},
   ISSN = {2352-3964},
   DOI = {10.1016/j.ebiom.2019.05.036},
   year = {2019},
   type = {Journal Article}
}

BACKGROUND: Despite promising treatments for breast cancer, mortality rates remain high and treatments for metastatic disease are limited. High-frequency irreversible electroporation (H-FIRE) is a novel tumor ablation technique that utilizes high-frequency bipolar electric pulses to destabilize cancer cell membranes and induce cell death. However, there is currently a paucity of data pertaining to immune system activation following H-FIRE and other electroporation based tumor ablation techniques. METHODS: Here, we utilized the mouse 4T1 mammary tumor model to evaluate H-FIRE treatment parameters on cancer progression and immune system activation in vitro and in vivo. FINDINGS: H-FIRE effectively ablates the primary tumor and induces a pro-inflammatory shift in the tumor microenvironment. We further show that local treatment with H-FIRE significantly reduces 4T1 metastases. H-FIRE kills 4T1 cells through non-thermal mechanisms associated with necrosis and pyroptosis resulting in damage associated molecular pattern signaling in vitro and in vivo. Our data indicate that the level of tumor ablation correlates with increased activation of cellular immunity. Likewise, we show that the decrease in metastatic lesions is dependent on the intact immune system and H-FIRE generates 4T1 neoantigens that engage the adaptive immune system to significantly attenuate tumor progression. INTERPRETATION: Cell death and tumor ablation following H-FIRE treatment activates the local innate immune system, which shifts the tumor microenvironment from an anti-inflammatory state to a pro-inflammatory state. The non-thermal damage to the cancer cells and increased innate immune system stimulation improves antigen presentation, resulting in the engagement of the adaptive immune system and improved systemic anti-tumor immunity.

@article{RN146,
   author = {Scheltema, M. J. and O'Brien, T. J. and van den Bos, W. and de Bruin, D. M. and Davalos, R. V. and van den Geld, C. W. M. and Laguna, M. P. and Neal, R. E., 2nd and Varkarakis, I. M. and Skolarikos, A. and Stricker, P. D. and de Reijke, T. M. and Arena, C. B. and de la Rosette, J.},
   title = {Numerical simulation modeling of the irreversible electroporation treatment zone for focal therapy of prostate cancer, correlation with whole-mount pathology and T2-weighted MRI sequences},
   journal = {Ther Adv Urol},
   volume = {11},
   pages = {1756287219852305},
   note = {1756-2880
Scheltema, Matthijs J
Orcid: 0000-0002-9098-9574
O'Brien, Tim J
van den Bos, Willemien
de Bruin, Daniel M
Davalos, Rafael V
van den Geld, Cees W M
Laguna, Maria P
Neal, Robert E 2nd
Varkarakis, Ioannis M
Skolarikos, Andreas
Stricker, Phillip D
de Reijke, Theo M
Arena, Christopher B
de la Rosette, Jean
Journal Article
England
2019/06/21
Ther Adv Urol. 2019 Jun 7;11:1756287219852305. doi: 10.1177/1756287219852305. eCollection 2019 Jan-Dec.},
   abstract = {BACKGROUND: At present, it is not possible to predict the ablation zone volume following irreversible electroporation (IRE) for prostate cancer (PCa). This study aimed to determine the necessary electrical field threshold to ablate human prostate tissue in vivo with IRE. METHODS: In this prospective multicenter trial, patients with localized PCa were treated with IRE 4 weeks before their scheduled radical prostatectomy. In 13 patients, numerical models of the electrical field were generated and compared with the ablation zone volume on whole-mount pathology and T2-weighted magnetic resonance imaging (MRI) sequences. Volume-generating software was used to calculate the ablation zone volumes on histology and MRI. The electric field threshold to ablate prostate tissue was determined for each patient. RESULTS: A total of 13 patients were included for histological and simulation analysis. The median electrical field threshold was 550 V/cm (interquartile range 383-750 V/cm) for the software-generated histology volumes. The median electrical field threshold was 500 V/cm (interquartile range 386-580 V/cm) when the ablation zone volumes were used from the follow-up MRI. CONCLUSIONS: The electrical field threshold to ablate human prostate tissue in vivo was determined using whole-mount pathology and MRI. These thresholds may be used to develop treatment planning or monitoring software for IRE prostate ablation; however, further optimization of simulation methods are required to decrease the variance that was observed between patients.},
   keywords = {electrical field
focal therapy
irreversible electroporation
prostate
prostate cancer
simulation},
   ISSN = {1756-2872 (Print)
1756-2872},
   DOI = {10.1177/1756287219852305},
   year = {2019},
   type = {Journal Article}
}

BACKGROUND: At present, it is not possible to predict the ablation zone volume following irreversible electroporation (IRE) for prostate cancer (PCa). This study aimed to determine the necessary electrical field threshold to ablate human prostate tissue in vivo with IRE. METHODS: In this prospective multicenter trial, patients with localized PCa were treated with IRE 4 weeks before their scheduled radical prostatectomy. In 13 patients, numerical models of the electrical field were generated and compared with the ablation zone volume on whole-mount pathology and T2-weighted magnetic resonance imaging (MRI) sequences. Volume-generating software was used to calculate the ablation zone volumes on histology and MRI. The electric field threshold to ablate prostate tissue was determined for each patient. RESULTS: A total of 13 patients were included for histological and simulation analysis. The median electrical field threshold was 550 V/cm (interquartile range 383-750 V/cm) for the software-generated histology volumes. The median electrical field threshold was 500 V/cm (interquartile range 386-580 V/cm) when the ablation zone volumes were used from the follow-up MRI. CONCLUSIONS: The electrical field threshold to ablate human prostate tissue in vivo was determined using whole-mount pathology and MRI. These thresholds may be used to develop treatment planning or monitoring software for IRE prostate ablation; however, further optimization of simulation methods are required to decrease the variance that was observed between patients.

@article{RN144,
   author = {Trainito, C. I. and Sweeney, D. C. and Čemažar, J. and Schmelz, E. M. and Français, O. and Le Pioufle, B. and Davalos, R. V.},
   title = {Characterization of sequentially-staged cancer cells using electrorotation},
   journal = {PLoS One},
   volume = {14},
   number = {9},
   pages = {e0222289},
   note = {1932-6203
Trainito, Claudia I
Orcid: 0000-0002-2728-9364
Sweeney, Daniel C
Orcid: 0000-0002-1289-1627
Čemažar, Jaka
Schmelz, Eva M
Français, Olivier
Le Pioufle, Bruno
Davalos, Rafael V
R01 CA213423/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2019/09/20
PLoS One. 2019 Sep 19;14(9):e0222289. doi: 10.1371/journal.pone.0222289. eCollection 2019.},
   abstract = {The identification and separation of cells from heterogeneous populations is critical to the diagnosis of diseases. Label-free methodologies in particular have been developed to manipulate individual cells using properties such as density and morphology. The electrical properties of malignant cells, including the membrane capacitance and cytoplasmic conductivity, have been demonstrated to be altered compared to non-malignant cells of similar origin. Here, we exploit these changes to characterize individual cells in a sequentially-staged in vitro cancer model using electrorotation (EROT)-the rotation of a cell induced by a rotating electric field. Using a microfabricated device, a dielectrophoretic force to suspend cells while measuring their angular velocity resulting from an EROT force applied at frequencies between 3 kHz to 10 MHz. We experimentally determine the EROT response for cells at three stages of malignancy and analyze the resultant spectra by considering models that include the effect of the cell membrane alone (single-shell model) and the combined effect of the cell membrane and nucleus (double-shell model). We find that the cell membrane is largely responsible for a given cell's EROT response between 3 kHz and 10 MHz. Our results also indicate that membrane capacitance, membrane conductance, and cytoplasmic conductivity increase with an increasingly malignant phenotype. Our results demonstrate the potential of using electrorotation as a means making of non-invasive measurements to characterize the dielectric properties of cancer cells.},
   keywords = {Animals
Cell Line, Tumor
Cell Membrane/pathology
Cell Separation/methods
Electric Conductivity
Electrodes
Mice
Models, Theoretical
Neoplasm Staging/*methods
Neoplasms/*pathology
Rotation},
   ISSN = {1932-6203},
   DOI = {10.1371/journal.pone.0222289},
   year = {2019},
   type = {Journal Article}
}

The identification and separation of cells from heterogeneous populations is critical to the diagnosis of diseases. Label-free methodologies in particular have been developed to manipulate individual cells using properties such as density and morphology. The electrical properties of malignant cells, including the membrane capacitance and cytoplasmic conductivity, have been demonstrated to be altered compared to non-malignant cells of similar origin. Here, we exploit these changes to characterize individual cells in a sequentially-staged in vitro cancer model using electrorotation (EROT)-the rotation of a cell induced by a rotating electric field. Using a microfabricated device, a dielectrophoretic force to suspend cells while measuring their angular velocity resulting from an EROT force applied at frequencies between 3 kHz to 10 MHz. We experimentally determine the EROT response for cells at three stages of malignancy and analyze the resultant spectra by considering models that include the effect of the cell membrane alone (single-shell model) and the combined effect of the cell membrane and nucleus (double-shell model). We find that the cell membrane is largely responsible for a given cell's EROT response between 3 kHz and 10 MHz. Our results also indicate that membrane capacitance, membrane conductance, and cytoplasmic conductivity increase with an increasingly malignant phenotype. Our results demonstrate the potential of using electrorotation as a means making of non-invasive measurements to characterize the dielectric properties of cancer cells.

@article{RN152,
   author = {Beitel-White, N. and Bhonsle, S. and Martin, R. C. G. and Davalos, R. V.},
   title = {Electrical Characterization of Human Biological Tissue for Irreversible Electroporation Treatments},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2018},
   pages = {4170-4173},
   note = {2694-0604
Beitel-White, Natalie
Bhonsle, Suyashree
Martin, R C G
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2018/11/18
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:4170-4173. doi: 10.1109/EMBC.2018.8513341.},
   abstract = {Irreversible electroporation (IRE) is a cancer therapy that uses short, high-voltage electrical pulses to treat tumors. Due to its predominantly non-thermal mechanism and ability to ablate unresectable tumors, IRE has gained popularity in clinical treatments of both liver and pancreatic cancers. Existing computational models use electrical properties of animal tissue that are quantified a priori to predict the area of treatment in three dimensions. However, the changes in the electrical properties of human tissue during IRE treatment are so far unexplored. This work aims to improve models by characterizing the dynamic electrical behavior of human liver and pancreatic tissue. Fresh patient samples of each tissue type, both normal and tumor, were collected and IRE pulses were applied between two parallel metal plates at various voltages. The electrical conductivity was determined from the resistance using simple relations applicable to cylindrical samples. The results indicate that the percent change in conductivity during IRE treatments varies significantly with increasing electric field magnitudes. This percent change versus applied electric field behavior can be fit to a sigmoidal curve, as proposed in prior studies. The generic conductivity data from human patients from this work can be input to computational software using patient-specific geometry, giving clinicians a more accurate and personalized prediction of a given IRE treatment.},
   keywords = {Animals
Electric Conductivity
*Electroporation
Humans
Liver
Metals
*Pancreatic Neoplasms},
   ISSN = {2375-7477},
   DOI = {10.1109/embc.2018.8513341},
   year = {2018},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a cancer therapy that uses short, high-voltage electrical pulses to treat tumors. Due to its predominantly non-thermal mechanism and ability to ablate unresectable tumors, IRE has gained popularity in clinical treatments of both liver and pancreatic cancers. Existing computational models use electrical properties of animal tissue that are quantified a priori to predict the area of treatment in three dimensions. However, the changes in the electrical properties of human tissue during IRE treatment are so far unexplored. This work aims to improve models by characterizing the dynamic electrical behavior of human liver and pancreatic tissue. Fresh patient samples of each tissue type, both normal and tumor, were collected and IRE pulses were applied between two parallel metal plates at various voltages. The electrical conductivity was determined from the resistance using simple relations applicable to cylindrical samples. The results indicate that the percent change in conductivity during IRE treatments varies significantly with increasing electric field magnitudes. This percent change versus applied electric field behavior can be fit to a sigmoidal curve, as proposed in prior studies. The generic conductivity data from human patients from this work can be input to computational software using patient-specific geometry, giving clinicians a more accurate and personalized prediction of a given IRE treatment.

@article{RN157,
   author = {Bhonsle, S. and Lorenzo, M. F. and Safaai-Jazi, A. and Davalos, R. V.},
   title = {Characterization of Nonlinearity and Dispersion in Tissue Impedance During High-Frequency Electroporation},
   journal = {IEEE Trans Biomed Eng},
   volume = {65},
   number = {10},
   pages = {2190-2201},
   note = {1558-2531
Bhonsle, Suyashree
Lorenzo, Melvin F
Safaai-Jazi, Ahmad
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2018/07/11
IEEE Trans Biomed Eng. 2018 Oct;65(10):2190-2201. doi: 10.1109/TBME.2017.2787038. Epub 2017 Dec 25.},
   abstract = {OBJECTIVE: The use of high-voltage, high-frequency bipolar pulses (HFBPs) is an emerging electroporation-based therapy for the treatment of solid tumors. In this study, we quantify the extent of nonlinearity and dispersion during the HFBP treatment. METHODS: We utilize flat-plate electrodes to capture the impedance of the porcine liver tissue during the delivery of a burst of HFBPs of widths 1 and 2  $\mu$s at different pulse amplitudes. Next, we fit the impedance data to a frequency-dependent parallel RC network to determine the conductivity and permittivity of the tissue as a function of frequency, for different applied electric fields. Finally, we present a simple model to approximate the field distribution in the tissue using the conductivity function at a frequency that could minimize the errors due to approximation with a nondispersive model. RESULTS: The conductivity/permittivity of the tissue was plotted as a function of frequency for different electric fields. It was found that the extent of dispersion reduces with higher applied electric field magnitudes. CONCLUSION: This is the first study to quantify dispersion and nonlinearity in the tissue during the HFBP treatment. The data have been used to predict the field distribution in a numerical model of the liver tissue utilizing two needle electrodes. SIGNIFICANCE: The data and technique developed in this study to monitor the electrical properties of tissue during treatment can be used to generate treatment-planning models for future high-frequency electroporation therapies as well as provide insights regarding treatment effect.},
   keywords = {Animals
*Electric Impedance
*Electrochemotherapy
Liver/physiology/*radiation effects
*Nonlinear Dynamics
Swine},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2017.2787038},
   year = {2018},
   type = {Journal Article}
}

OBJECTIVE: The use of high-voltage, high-frequency bipolar pulses (HFBPs) is an emerging electroporation-based therapy for the treatment of solid tumors. In this study, we quantify the extent of nonlinearity and dispersion during the HFBP treatment. METHODS: We utilize flat-plate electrodes to capture the impedance of the porcine liver tissue during the delivery of a burst of HFBPs of widths 1 and 2 $μ$s at different pulse amplitudes. Next, we fit the impedance data to a frequency-dependent parallel RC network to determine the conductivity and permittivity of the tissue as a function of frequency, for different applied electric fields. Finally, we present a simple model to approximate the field distribution in the tissue using the conductivity function at a frequency that could minimize the errors due to approximation with a nondispersive model. RESULTS: The conductivity/permittivity of the tissue was plotted as a function of frequency for different electric fields. It was found that the extent of dispersion reduces with higher applied electric field magnitudes. CONCLUSION: This is the first study to quantify dispersion and nonlinearity in the tissue during the HFBP treatment. The data have been used to predict the field distribution in a numerical model of the liver tissue utilizing two needle electrodes. SIGNIFICANCE: The data and technique developed in this study to monitor the electrical properties of tissue during treatment can be used to generate treatment-planning models for future high-frequency electroporation therapies as well as provide insights regarding treatment effect.

@article{RN161,
   author = {Cho, H. J. and Verbridge, S. S. and Davalos, R. V. and Lee, Y. W.},
   title = {Development of an In Vitro 3D Brain Tissue Model Mimicking In Vivo-Like Pro-inflammatory and Pro-oxidative Responses},
   journal = {Ann Biomed Eng},
   volume = {46},
   number = {6},
   pages = {877-887},
   note = {1573-9686
Cho, Hyung Joon
Verbridge, Scott S
Davalos, Rafael V
Lee, Yong W
Journal Article
United States
2018/03/04
Ann Biomed Eng. 2018 Jun;46(6):877-887. doi: 10.1007/s10439-018-2004-z. Epub 2018 Mar 2.},
   abstract = {To analyze complex inflammatory responses in an in vitro system, we constructed a new 3D in vitro brain tissue model that exhibits in vivo-like tissue responses (e.g. immune cell phenotypes, and molecular response) to inflammatory stimuli. Finite element modeling of oxygen diffusion and cellular oxygen consumption predicted the oxygen profile within 3D structures, consisting of Type I collagen hydrogel embedded with murine microglia. Viability and cytotoxicity analyses supported the mathematical analysis, determining optimal cell growth conditions for 3D construct development. Real-time RT-PCR and ELISA demonstrated significant up-regulation of pro-inflammatory mediators, such as TNF-α, MCP-1, IL-6 and IL-1β, in lipopolysaccharide (LPS)-stimulated in vitro cell culture (2D and 3D) and in vivo mouse model systems. Interestingly, levels of inflammatory responses from the in vitro 3D model system were more similar to in vivo than in vitro 2D. Additionally, in situ dihydroethidium (DHE) assay and immunofluorescence staining revealed that levels of LPS-stimulated reactive oxygen species (ROS) generation and microglial activation from in vitro 3D model system were closer to in vivo than in vitro 2D. These results demonstrated that an in vitro 3D model provides more physiologically relevant pro-oxidative and pro-inflammatory environments in brain than an in vitro 2D model.},
   keywords = {Animals
Cell Culture Techniques
Cell Line
Collagen Type I/*chemistry
Cytokines/metabolism
Hydrogels/*chemistry
Inflammation/chemically induced/metabolism/pathology
Lipopolysaccharides/toxicity
Mice
Microglia/*metabolism/pathology
*Models, Biological
*Oxidative Stress
Rats
Collagen hydrogel
Cytokines
Lipopolysaccharide
Microglia
Reactive oxygen species},
   ISSN = {0090-6964},
   DOI = {10.1007/s10439-018-2004-z},
   year = {2018},
   type = {Journal Article}
}

To analyze complex inflammatory responses in an in vitro system, we constructed a new 3D in vitro brain tissue model that exhibits in vivo-like tissue responses (e.g. immune cell phenotypes, and molecular response) to inflammatory stimuli. Finite element modeling of oxygen diffusion and cellular oxygen consumption predicted the oxygen profile within 3D structures, consisting of Type I collagen hydrogel embedded with murine microglia. Viability and cytotoxicity analyses supported the mathematical analysis, determining optimal cell growth conditions for 3D construct development. Real-time RT-PCR and ELISA demonstrated significant up-regulation of pro-inflammatory mediators, such as TNF-α, MCP-1, IL-6 and IL-1β, in lipopolysaccharide (LPS)-stimulated in vitro cell culture (2D and 3D) and in vivo mouse model systems. Interestingly, levels of inflammatory responses from the in vitro 3D model system were more similar to in vivo than in vitro 2D. Additionally, in situ dihydroethidium (DHE) assay and immunofluorescence staining revealed that levels of LPS-stimulated reactive oxygen species (ROS) generation and microglial activation from in vitro 3D model system were closer to in vivo than in vitro 2D. These results demonstrated that an in vitro 3D model provides more physiologically relevant pro-oxidative and pro-inflammatory environments in brain than an in vitro 2D model.

@article{RN160,
   author = {Hyler, A. R. and Baudoin, N. C. and Brown, M. S. and Stremler, M. A. and Cimini, D. and Davalos, R. V. and Schmelz, E. M.},
   title = {Fluid shear stress impacts ovarian cancer cell viability, subcellular organization, and promotes genomic instability},
   journal = {PLoS One},
   volume = {13},
   number = {3},
   pages = {e0194170},
   note = {1932-6203
Hyler, Alexandra R
Orcid: 0000-0002-8698-4455
Baudoin, Nicolaas C
Brown, Megan S
Stremler, Mark A
Cimini, Daniela
Davalos, Rafael V
Schmelz, Eva M
Journal Article
Research Support, Non-U.S. Gov't
United States
2018/03/23
PLoS One. 2018 Mar 22;13(3):e0194170. doi: 10.1371/journal.pone.0194170. eCollection 2018.},
   abstract = {Ovarian cancer cells are exposed to physical stress in the peritoneal cavity during both tumor growth and dissemination. Ascites build-up in metastatic ovarian cancer further increases the exposure to fluid shear stress. Here, we used a murine, in vitro ovarian cancer progression model in parallel with immortalized human cells to investigate how ovarian cancer cells of increasing aggressiveness respond to [Formula: see text] of fluid-induced shear stress. This biophysical stimulus significantly reduced cell viability in all cells exposed, independent of disease stage. Fluid shear stress induced spheroid formation and altered cytoskeleton organization in more tumorigenic cell lines. While benign ovarian cells appeared to survive in higher numbers under the influence of fluid shear stress, they exhibited severe morphological changes and chromosomal instability. These results suggest that exposure of benign cells to low magnitude fluid shear stress can induce phenotypic changes that are associated with transformation and ovarian cancer progression. Moreover, exposure of tumorigenic cells to fluid shear stress enhanced anchorage-independent survival, suggesting a role in promoting invasion and metastasis.},
   keywords = {Animals
Cell Line, Tumor
Cell Survival
Cytoskeleton/*metabolism/pathology
Female
*Genomic Instability
Humans
Mice
Neoplasm Invasiveness
Neoplasm Metastasis
Ovarian Neoplasms/*metabolism/pathology
*Shear Strength
*Stress, Mechanical},
   ISSN = {1932-6203},
   DOI = {10.1371/journal.pone.0194170},
   year = {2018},
   type = {Journal Article}
}

Ovarian cancer cells are exposed to physical stress in the peritoneal cavity during both tumor growth and dissemination. Ascites build-up in metastatic ovarian cancer further increases the exposure to fluid shear stress. Here, we used a murine, in vitro ovarian cancer progression model in parallel with immortalized human cells to investigate how ovarian cancer cells of increasing aggressiveness respond to [Formula: see text] of fluid-induced shear stress. This biophysical stimulus significantly reduced cell viability in all cells exposed, independent of disease stage. Fluid shear stress induced spheroid formation and altered cytoskeleton organization in more tumorigenic cell lines. While benign ovarian cells appeared to survive in higher numbers under the influence of fluid shear stress, they exhibited severe morphological changes and chromosomal instability. These results suggest that exposure of benign cells to low magnitude fluid shear stress can induce phenotypic changes that are associated with transformation and ovarian cancer progression. Moreover, exposure of tumorigenic cells to fluid shear stress enhanced anchorage-independent survival, suggesting a role in promoting invasion and metastasis.

@article{RN156,
   author = {Latouche, E. L. and Arena, C. B. and Ivey, J. W. and Garcia, P. A. and Pancotto, T. E. and Pavlisko, N. and Verbridge, S. S. and Davalos, R. V. and Rossmeisl, J. H.},
   title = {High-Frequency Irreversible Electroporation for Intracranial Meningioma: A Feasibility Study in a Spontaneous Canine Tumor Model},
   journal = {Technol Cancer Res Treat},
   volume = {17},
   pages = {1533033818785285},
   note = {1533-0338
Latouche, Eduardo L
Arena, Christopher B
Ivey, Jill W
Garcia, Paulo A
Pancotto, Theresa E
Pavlisko, Noah
Verbridge, Scott S
Davalos, Rafael V
Rossmeisl, John H
Orcid: 0000-0003-1655-7076
Journal Article
Research Support, Non-U.S. Gov't
United States
2018/08/04
Technol Cancer Res Treat. 2018 Jan 1;17:1533033818785285. doi: 10.1177/1533033818785285.},
   abstract = {High-frequency irreversible electroporation is a nonthermal method of tissue ablation that uses bursts of 0.5- to 2.0-microsecond bipolar electric pulses to permeabilize cell membranes and induce cell death. High-frequency irreversible electroporation has potential advantages for use in neurosurgery, including the ability to deliver pulses without inducing muscle contraction, inherent selectivity against malignant cells, and the capability of simultaneously opening the blood-brain barrier surrounding regions of ablation. Our objective was to determine whether high-frequency irreversible electroporation pulses capable of tumor ablation could be delivered to dogs with intracranial meningiomas. Three dogs with intracranial meningiomas were treated. Patient-specific treatment plans were generated using magnetic resonance imaging-based tissue segmentation, volumetric meshing, and finite element modeling. Following tumor biopsy, high-frequency irreversible electroporation pulses were stereotactically delivered in situ followed by tumor resection and morphologic and volumetric assessments of ablations. Clinical evaluations of treatment included pre- and posttreatment clinical, laboratory, and magnetic resonance imaging examinations and adverse event monitoring for 2 weeks posttreatment. High-frequency irreversible electroporation pulses were administered successfully in all patients. No adverse events directly attributable to high-frequency irreversible electroporation were observed. Individual ablations resulted in volumes of tumor necrosis ranging from 0.25 to 1.29 cm(3). In one dog, nonuniform ablations were observed, with viable tumor cells remaining around foci of intratumoral mineralization. In conclusion, high-frequency irreversible electroporation pulses can be delivered to brain tumors, including areas adjacent to critical vasculature, and are capable of producing clinically relevant volumes of tumor ablation. Mineralization may complicate achievement of complete tumor ablation.},
   keywords = {Animals
Brain Neoplasms/diagnostic imaging/pathology/*radiotherapy
Disease Models, Animal
Dogs
Electrochemotherapy/*methods
Feasibility Studies
Female
Humans
Magnetic Resonance Imaging
Meningioma/diagnostic imaging/pathology/*radiotherapy
animal models
brain tumor
dog
neuro-oncology
pulsed electric fields},
   ISSN = {1533-0346 (Print)
1533-0338},
   DOI = {10.1177/1533033818785285},
   year = {2018},
   type = {Journal Article}
}

High-frequency irreversible electroporation is a nonthermal method of tissue ablation that uses bursts of 0.5- to 2.0-microsecond bipolar electric pulses to permeabilize cell membranes and induce cell death. High-frequency irreversible electroporation has potential advantages for use in neurosurgery, including the ability to deliver pulses without inducing muscle contraction, inherent selectivity against malignant cells, and the capability of simultaneously opening the blood-brain barrier surrounding regions of ablation. Our objective was to determine whether high-frequency irreversible electroporation pulses capable of tumor ablation could be delivered to dogs with intracranial meningiomas. Three dogs with intracranial meningiomas were treated. Patient-specific treatment plans were generated using magnetic resonance imaging-based tissue segmentation, volumetric meshing, and finite element modeling. Following tumor biopsy, high-frequency irreversible electroporation pulses were stereotactically delivered in situ followed by tumor resection and morphologic and volumetric assessments of ablations. Clinical evaluations of treatment included pre- and posttreatment clinical, laboratory, and magnetic resonance imaging examinations and adverse event monitoring for 2 weeks posttreatment. High-frequency irreversible electroporation pulses were administered successfully in all patients. No adverse events directly attributable to high-frequency irreversible electroporation were observed. Individual ablations resulted in volumes of tumor necrosis ranging from 0.25 to 1.29 cm(3). In one dog, nonuniform ablations were observed, with viable tumor cells remaining around foci of intratumoral mineralization. In conclusion, high-frequency irreversible electroporation pulses can be delivered to brain tumors, including areas adjacent to critical vasculature, and are capable of producing clinically relevant volumes of tumor ablation. Mineralization may complicate achievement of complete tumor ablation.

@article{RN159,
   author = {O'Brien, T. J. and Bonakdar, M. and Bhonsle, S. and Neal, R. E., 2nd and Aardema, C. H., Jr. and Robertson, J. L. and Goldberg, S. N. and Davalos, R. V.},
   title = {Effects of internal electrode cooling on irreversible electroporation using a perfused organ model},
   journal = {Int J Hyperthermia},
   volume = {35},
   number = {1},
   pages = {44-55},
   note = {1464-5157
O'Brien, Timothy J
Bonakdar, Mohammad
Bhonsle, Suyashree
Neal, Robert E 2nd
Aardema, Charles H Jr
Robertson, John L
Goldberg, S Nahum
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
England
2018/05/29
Int J Hyperthermia. 2018;35(1):44-55. doi: 10.1080/02656736.2018.1473893. Epub 2018 May 28.},
   abstract = {PURPOSE: This study evaluates the effects of active electrode cooling, via internal fluid circulation, on the irreversible electroporation (IRE) lesion, deployed electric current and temperature changes using a perfused porcine liver model. MATERIALS AND METHODS: A bipolar electrode delivered IRE electric pulses with or without activation of internal cooling to nine porcine mechanically perfused livers. Pulse schemes included a constant voltage, and a preconditioned delivery combined with an arc-mitigation algorithm. After treatment, organs were dissected, and treatment zones were stained using triphenyl-tetrazolium chloride (TTC) to demonstrate viability. RESULTS: Thirty-nine treatments were performed with an internally cooled applicator and 21 with a non-cooled applicator. For the constant voltage scenario, the average final electrical current measured was 26.37 and 29.20 A for the cooled and uncooled electrodes respectively ([Formula: see text]). The average final temperature measured was 33.01 and 42.43 °C for the cooled and uncooled electrodes respectively ([Formula: see text]). The average measured ablations (fixed lesion) were 3.88-by-2.08 cm and 3.86-by-2.12 cm for the cooled and uncooled electrode respectively ([Formula: see text], [Formula: see text]). Similarly, the preconditioned/arc-mitigation scenario yielded an average final electrical current measurement of a 41.07 and 47.20 A for the cooled and uncooled electrodes respectively ([Formula: see text]). The average final temperature measured was 34.93 and 44.90 °C for the cooled and uncooled electrodes respectively ([Formula: see text]). The average measured ablations (fixed lesion) were 3.67-by-2.27 cm and 3.58-by-2.09 cm for the cooled and uncooled applicators ([Formula: see text]). CONCLUSIONS: The internally-cooled bipolar applicator offers advantages that could improve clinical outcomes. Thermally mitigating internal perfusion technology reduced tissue temperatures and electric current while maintaining similar lesion sizes.},
   keywords = {Ablation Techniques/*methods
Animals
Cold Temperature
Disease Models, Animal
Electrodes
Electroporation/*methods
Liver/pathology/*surgery
Swine
Irreversible electroporation
arc mitigation
current
perfused organ model
temperature
thermal damage
thermal mitigation},
   ISSN = {0265-6736},
   DOI = {10.1080/02656736.2018.1473893},
   year = {2018},
   type = {Journal Article}
}

PURPOSE: This study evaluates the effects of active electrode cooling, via internal fluid circulation, on the irreversible electroporation (IRE) lesion, deployed electric current and temperature changes using a perfused porcine liver model. MATERIALS AND METHODS: A bipolar electrode delivered IRE electric pulses with or without activation of internal cooling to nine porcine mechanically perfused livers. Pulse schemes included a constant voltage, and a preconditioned delivery combined with an arc-mitigation algorithm. After treatment, organs were dissected, and treatment zones were stained using triphenyl-tetrazolium chloride (TTC) to demonstrate viability. RESULTS: Thirty-nine treatments were performed with an internally cooled applicator and 21 with a non-cooled applicator. For the constant voltage scenario, the average final electrical current measured was 26.37 and 29.20 A for the cooled and uncooled electrodes respectively ([Formula: see text]). The average final temperature measured was 33.01 and 42.43 °C for the cooled and uncooled electrodes respectively ([Formula: see text]). The average measured ablations (fixed lesion) were 3.88-by-2.08 cm and 3.86-by-2.12 cm for the cooled and uncooled electrode respectively ([Formula: see text], [Formula: see text]). Similarly, the preconditioned/arc-mitigation scenario yielded an average final electrical current measurement of a 41.07 and 47.20 A for the cooled and uncooled electrodes respectively ([Formula: see text]). The average final temperature measured was 34.93 and 44.90 °C for the cooled and uncooled electrodes respectively ([Formula: see text]). The average measured ablations (fixed lesion) were 3.67-by-2.27 cm and 3.58-by-2.09 cm for the cooled and uncooled applicators ([Formula: see text]). CONCLUSIONS: The internally-cooled bipolar applicator offers advantages that could improve clinical outcomes. Thermally mitigating internal perfusion technology reduced tissue temperatures and electric current while maintaining similar lesion sizes.

@article{RN151,
   author = {Sweeney, D. C. and Davalos, R. V.},
   title = {Discontinuous Galerkin Model of Cellular Electroporation},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2018},
   pages = {5850-5853},
   note = {2694-0604
Sweeney, Daniel C
Davalos, Rafael V
R01 CA213423/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
United States
2018/11/18
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:5850-5853. doi: 10.1109/EMBC.2018.8513541.},
   abstract = {Electroporation (EP) is a phenomenon involving both nonlinear biophysical processes and complex geometries. When exposed to strong electric fields, the formation of pores within a cell membrane increases the membrane permeability. Discontinuous Galerkin (DG) finite element methods can directly enforce these flux jumps across the thin cell membrane interface. We implement a DG finite element method to model the electric field, pore formation, and transmembrane flux of charged solutes during EP. Our model is readily extensible for parallel computation on high performance clusters and agrees with previous reports.},
   keywords = {Cell Membrane/physiology
*Cell Membrane Permeability
*Electroporation
Finite Element Analysis
Models, Biological},
   ISSN = {2375-7477},
   DOI = {10.1109/embc.2018.8513541},
   year = {2018},
   type = {Journal Article}
}

Electroporation (EP) is a phenomenon involving both nonlinear biophysical processes and complex geometries. When exposed to strong electric fields, the formation of pores within a cell membrane increases the membrane permeability. Discontinuous Galerkin (DG) finite element methods can directly enforce these flux jumps across the thin cell membrane interface. We implement a DG finite element method to model the electric field, pore formation, and transmembrane flux of charged solutes during EP. Our model is readily extensible for parallel computation on high performance clusters and agrees with previous reports.

@article{RN155,
   author = {Sweeney, D. C. and Douglas, T. A. and Davalos, R. V.},
   title = {Characterization of Cell Membrane Permeability In Vitro Part II: Computational Model of Electroporation-Mediated Membrane Transport},
   journal = {Technol Cancer Res Treat},
   volume = {17},
   pages = {1533033818792490},
   note = {1533-0338
Sweeney, Daniel C
Orcid: 0000-0002-1289-1627
Douglas, Temple A
Davalos, Rafael V
R01 CA213423/CA/NCI NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
United States
2018/09/21
Technol Cancer Res Treat. 2018 Jan 1;17:1533033818792490. doi: 10.1177/1533033818792490.},
   abstract = {Electroporation is the process by which applied electric fields generate nanoscale defects in biological membranes to more efficiently deliver drugs and other small molecules into the cells. Due to the complexity of the process, computational models of cellular electroporation are difficult to validate against quantitative molecular uptake data. In part I of this two-part report, we describe a novel method for quantitatively determining cell membrane permeability and molecular membrane transport using fluorescence microscopy. Here, in part II, we use the data from part I to develop a two-stage ordinary differential equation model of cellular electroporation. We fit our model using experimental data from cells immersed in three buffer solutions and exposed to electric field strengths of 170 to 400 kV/m and pulse durations of 1 to 1000 μs. We report that a low-conductivity 4-(2-hydroxyethyl)-1 piperazineethanesulfonic acid buffer enables molecular transport into the cell to increase more rapidly than with phosphate-buffered saline or culture medium-based buffer. For multipulse schemes, our model suggests that the interpulse delay between two opposite polarity electric field pulses does not play an appreciable role in the resultant molecular uptake for delays up to 100 μs. Our model also predicts the per-pulse permeability enhancement decreases as a function of the pulse number. This is the first report of an ordinary differential equation model of electroporation to be validated with quantitative molecular uptake data and consider both membrane permeability and charging.},
   keywords = {Biological Transport/*physiology
Cell Membrane/*physiology
Cell Membrane Permeability/*physiology
Computer Simulation
Electrochemotherapy/methods
Electroporation/methods
differential equation
diffusion
permeability
porosity
pulsed electric fields
solute},
   ISSN = {1533-0346 (Print)
1533-0338},
   DOI = {10.1177/1533033818792490},
   year = {2018},
   type = {Journal Article}
}

Electroporation is the process by which applied electric fields generate nanoscale defects in biological membranes to more efficiently deliver drugs and other small molecules into the cells. Due to the complexity of the process, computational models of cellular electroporation are difficult to validate against quantitative molecular uptake data. In part I of this two-part report, we describe a novel method for quantitatively determining cell membrane permeability and molecular membrane transport using fluorescence microscopy. Here, in part II, we use the data from part I to develop a two-stage ordinary differential equation model of cellular electroporation. We fit our model using experimental data from cells immersed in three buffer solutions and exposed to electric field strengths of 170 to 400 kV/m and pulse durations of 1 to 1000 μs. We report that a low-conductivity 4-(2-hydroxyethyl)-1 piperazineethanesulfonic acid buffer enables molecular transport into the cell to increase more rapidly than with phosphate-buffered saline or culture medium-based buffer. For multipulse schemes, our model suggests that the interpulse delay between two opposite polarity electric field pulses does not play an appreciable role in the resultant molecular uptake for delays up to 100 μs. Our model also predicts the per-pulse permeability enhancement decreases as a function of the pulse number. This is the first report of an ordinary differential equation model of electroporation to be validated with quantitative molecular uptake data and consider both membrane permeability and charging.

@article{RN154,
   author = {Sweeney, D. C. and Weaver, J. C. and Davalos, R. V.},
   title = {Characterization of Cell Membrane Permeability In Vitro Part I: Transport Behavior Induced by Single-Pulse Electric Fields},
   journal = {Technol Cancer Res Treat},
   volume = {17},
   pages = {1533033818792491},
   note = {1533-0338
Sweeney, Daniel C
Orcid: 0000-0002-1289-1627
Weaver, James C
Davalos, Rafael V
P01 CA207206/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
United States
2018/09/22
Technol Cancer Res Treat. 2018 Jan 1;17:1533033818792491. doi: 10.1177/1533033818792491.},
   abstract = {Most experimental studies of electroporation focus on permeabilization of the outer cell membrane. Some experiments address delivery of ions and molecules into cells that should survive; others focus on efficient killing of the cells with minimal temperature rise. A basic method for quantifying electroporation effectiveness is measuring the membrane's diffusive permeability. More specifically, comparisons of membrane permeability between electroporation protocols often rely on relative fluorescence measurements, which are not able to be directly connected to theoretical calculations and complicate comparisons between studies. Here we present part I of a 2-part study: a research method for quantitatively determining the membrane diffusive permeability for individual cells using fluorescence microscopy. We determine diffusive permeabilities of cell membranes to propidium for electric field pulses with durations of 1 to 1000 μs and strengths of 170 to 400 kV/m and show that diffusive permeabilities can reach 1.3±0.4×10-8 m/s. This leads to a correlation between increased membrane permeability and eventual propidium uptake. We also identify a subpopulation of cells that exhibit a delayed and significant propidium uptake for relatively small single pulses. Our results provide evidence that cells, especially those that uptake propidium more slowly, can achieve large permeabilities with a single electrical pulse that may be quantitatively measured using standard fluorescence microscopy equipment and techniques.},
   keywords = {Biological Transport/*physiology
Cell Membrane/metabolism/*physiology
Cell Membrane Permeability/*physiology
Electrochemotherapy/methods
Electromagnetic Fields
Electroporation/methods
Propidium/metabolism
diffusion
electroporation
propidium
pulsed electric fields
transport},
   ISSN = {1533-0346 (Print)
1533-0338},
   DOI = {10.1177/1533033818792491},
   year = {2018},
   type = {Journal Article}
}

Most experimental studies of electroporation focus on permeabilization of the outer cell membrane. Some experiments address delivery of ions and molecules into cells that should survive; others focus on efficient killing of the cells with minimal temperature rise. A basic method for quantifying electroporation effectiveness is measuring the membrane's diffusive permeability. More specifically, comparisons of membrane permeability between electroporation protocols often rely on relative fluorescence measurements, which are not able to be directly connected to theoretical calculations and complicate comparisons between studies. Here we present part I of a 2-part study: a research method for quantitatively determining the membrane diffusive permeability for individual cells using fluorescence microscopy. We determine diffusive permeabilities of cell membranes to propidium for electric field pulses with durations of 1 to 1000 μs and strengths of 170 to 400 kV/m and show that diffusive permeabilities can reach 1.3±0.4×10-8 m/s. This leads to a correlation between increased membrane permeability and eventual propidium uptake. We also identify a subpopulation of cells that exhibit a delayed and significant propidium uptake for relatively small single pulses. Our results provide evidence that cells, especially those that uptake propidium more slowly, can achieve large permeabilities with a single electrical pulse that may be quantitatively measured using standard fluorescence microscopy equipment and techniques.

@article{RN158,
   author = {Zhao, Y. and Bhonsle, S. and Dong, S. and Lv, Y. and Liu, H. and Safaai-Jazi, A. and Davalos, R. V. and Yao, C.},
   title = {Characterization of Conductivity Changes During High-Frequency Irreversible Electroporation for Treatment Planning},
   journal = {IEEE Trans Biomed Eng},
   volume = {65},
   number = {8},
   pages = {1810-1819},
   note = {1558-2531
Zhao, Yajun
Bhonsle, Suyashree
Dong, Shoulong
Lv, Yanpeng
Liu, Hongmei
Safaai-Jazi, Ahmad
Davalos, Rafael V
Yao, Chenguo
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2018/07/11
IEEE Trans Biomed Eng. 2018 Aug;65(8):1810-1819. doi: 10.1109/TBME.2017.2778101. Epub 2017 Nov 28.},
   abstract = {For irreversible-electroporation (IRE)-based therapies, the underlying electric field distribution in the target tissue is influenced by the electroporation-induced conductivity changes and is important for predicting the treatment zone. OBJECTIVE: In this study, we characterized the liver tissue conductivity changes during high-frequency irreversible electroporation (H-FIRE) treatments of widths 5 and 10 μs and proposed a method for predicting the ablation zones. METHODS: To achieve this, we created a finite-element model of the tissue treated with H-FIRE and IRE pulses based on experiments conducted in an in-vivo rabbit liver study. We performed a parametric sweep on a Heaviside function that captured the tissue conductivity versus electric field behavior to yield a model current close to the experimental current during the first burst/pulse. A temperature module was added to account for the current increase in subsequent bursts/pulses. The evolution of the electric field at the end of the treatment was overlaid on the experimental ablation zones determined from hematoxylin and eosin staining to find the field thresholds of ablation. RESULTS: Dynamic conductivity curves that provided a statistically significant relation between the model and experimental results were determined for H-FIRE. In addition, the field thresholds of ablation were obtained for the tested H-FIRE parameters. CONCLUSION: The proposed numerical model can simulate the electroporation process during H-FIRE. SIGNIFICANCE: The treatment planning method developed in this study can be translated to H-FIRE treatments of different widths and for different tissue types.},
   keywords = {Animals
Electric Conductivity
Electrochemotherapy/*methods
Finite Element Analysis
Liver/physiology
*Models, Biological
Rabbits
*Signal Processing, Computer-Assisted},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2017.2778101},
   year = {2018},
   type = {Journal Article}
}

For irreversible-electroporation (IRE)-based therapies, the underlying electric field distribution in the target tissue is influenced by the electroporation-induced conductivity changes and is important for predicting the treatment zone. OBJECTIVE: In this study, we characterized the liver tissue conductivity changes during high-frequency irreversible electroporation (H-FIRE) treatments of widths 5 and 10 μs and proposed a method for predicting the ablation zones. METHODS: To achieve this, we created a finite-element model of the tissue treated with H-FIRE and IRE pulses based on experiments conducted in an in-vivo rabbit liver study. We performed a parametric sweep on a Heaviside function that captured the tissue conductivity versus electric field behavior to yield a model current close to the experimental current during the first burst/pulse. A temperature module was added to account for the current increase in subsequent bursts/pulses. The evolution of the electric field at the end of the treatment was overlaid on the experimental ablation zones determined from hematoxylin and eosin staining to find the field thresholds of ablation. RESULTS: Dynamic conductivity curves that provided a statistically significant relation between the model and experimental results were determined for H-FIRE. In addition, the field thresholds of ablation were obtained for the tested H-FIRE parameters. CONCLUSION: The proposed numerical model can simulate the electroporation process during H-FIRE. SIGNIFICANCE: The treatment planning method developed in this study can be translated to H-FIRE treatments of different widths and for different tissue types.

@article{RN153,
   author = {Zhao, Y. and Liu, H. and Bhonsle, S. P. and Wang, Y. and Davalos, R. V. and Yao, C.},
   title = {Ablation outcome of irreversible electroporation on potato monitored by impedance spectrum under multi-electrode system},
   journal = {Biomed Eng Online},
   volume = {17},
   number = {1},
   pages = {126},
   note = {1475-925x
Zhao, Yajun
Orcid: 0000-0003-3029-0291
Liu, Hongmei
Bhonsle, Suyashree P
Wang, Yilin
Davalos, Rafael V
Yao, Chenguo
cstc2014jcyjjq90001/Natural Science Foundation Project of CQ CSTC/
CYB17011/Graduate Scientific Research and Innovation Foundation of Chongqing/
106112017CDJQJ158835/Fundamental Re-search Funds for the Central Universities/
PanCAN 16-65-IANN/the pancreatic cancer action network translational research Grant/
Journal Article
England
2018/09/22
Biomed Eng Online. 2018 Sep 20;17(1):126. doi: 10.1186/s12938-018-0562-9.},
   abstract = {BACKGROUND: Irreversible electroporation (IRE) therapy relies on pulsed electric fields to non-thermally ablate cancerous tissue. Methods for evaluating IRE ablation in situ are critical to assessing treatment outcome. Analyzing changes in tissue impedance caused by electroporation has been proposed as a method for quantifying IRE ablation. In this paper, we assess the hypothesis that irreversible electroporation ablation outcome can be monitored using the impedance change measured by the electrode pairs not in use, getting more information about the ablation size in different directions. METHODS: Using a square four-electrode configuration, the two diagonal electrodes were used to electroporate potato tissue. Next, the impedance changes, before and after treatment, were measured from different electrode pairs and the impedance information was extracted by fitting the data to an equivalent circuit model. Finally, we correlated the change of impedance from various electrode pairs to the ablation geometry through the use of fitted functions; then these functions were used to predict the ablation size and compared to the numerical simulation results. RESULTS: The change in impedance from the electrodes used to apply pulses is larger and has higher deviation than the other electrode pairs. The ablation size and the change in resistance in the circuit model correlate with various linear functions. The coefficients of determination for the three functions are 0.8121, 0.8188 and 0.8691, respectively, showing satisfactory agreement. The functions can well predict the ablation size under different pulse numbers, and in some directions it did even better than the numerical simulation method, which used different electric field thresholds for different pulse numbers. CONCLUSIONS: The relative change in tissue impedance measured from the non-energized electrodes can be used to assess ablation size during treatment with IRE according to linear functions.},
   keywords = {Ablation Techniques/*instrumentation
Electric Impedance
Electrodes
Electroporation/*instrumentation
Equipment Design
Solanum tuberosum/*cytology
Ablation size
Bioimpedance
Electroporation assessment
Equivalent circuit model
Irreversible electroporation
Tumor therapy},
   ISSN = {1475-925x},
   DOI = {10.1186/s12938-018-0562-9},
   year = {2018},
   type = {Journal Article}
}

BACKGROUND: Irreversible electroporation (IRE) therapy relies on pulsed electric fields to non-thermally ablate cancerous tissue. Methods for evaluating IRE ablation in situ are critical to assessing treatment outcome. Analyzing changes in tissue impedance caused by electroporation has been proposed as a method for quantifying IRE ablation. In this paper, we assess the hypothesis that irreversible electroporation ablation outcome can be monitored using the impedance change measured by the electrode pairs not in use, getting more information about the ablation size in different directions. METHODS: Using a square four-electrode configuration, the two diagonal electrodes were used to electroporate potato tissue. Next, the impedance changes, before and after treatment, were measured from different electrode pairs and the impedance information was extracted by fitting the data to an equivalent circuit model. Finally, we correlated the change of impedance from various electrode pairs to the ablation geometry through the use of fitted functions; then these functions were used to predict the ablation size and compared to the numerical simulation results. RESULTS: The change in impedance from the electrodes used to apply pulses is larger and has higher deviation than the other electrode pairs. The ablation size and the change in resistance in the circuit model correlate with various linear functions. The coefficients of determination for the three functions are 0.8121, 0.8188 and 0.8691, respectively, showing satisfactory agreement. The functions can well predict the ablation size under different pulse numbers, and in some directions it did even better than the numerical simulation method, which used different electric field thresholds for different pulse numbers. CONCLUSIONS: The relative change in tissue impedance measured from the non-energized electrodes can be used to assess ablation size during treatment with IRE according to linear functions.

@article{RN170,
   author = {Douglas, T. A. and Cemazar, J. and Balani, N. and Sweeney, D. C. and Schmelz, E. M. and Davalos, R. V.},
   title = {A feasibility study for enrichment of highly aggressive cancer subpopulations by their biophysical properties via dielectrophoresis enhanced with synergistic fluid flow},
   journal = {Electrophoresis},
   volume = {38},
   number = {11},
   pages = {1507-1514},
   note = {1522-2683
Douglas, Temple Anne
Cemazar, Jaka
Balani, Nikita
Sweeney, Daniel C
Schmelz, Eva M
Davalos, Rafael V
R21 CA173092/CA/NCI NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
Germany
2017/03/28
Electrophoresis. 2017 Jun;38(11):1507-1514. doi: 10.1002/elps.201600530. Epub 2017 May 8.},
   abstract = {A common problem with cancer treatment is the development of treatment resistance and tumor recurrence that result from treatments that kill most tumor cells yet leave behind aggressive cells to repopulate. Presented here is a microfluidic device that can be used to isolate tumor subpopulations to optimize treatment selection. Dielectrophoresis (DEP) is a phenomenon where particles are polarized by an electric field and move along the electric field gradient. Different cell subpopulations have different DEP responses depending on their bioelectrical phenotype, which, we hypothesize, correlate with aggressiveness. We have designed a microfluidic device in which a region containing posts locally distorts the electric field created by an AC voltage and forces cells toward the posts through DEP. This force is balanced with a simultaneous drag force from fluid motion that pulls cells away from the posts. We have shown that by adjusting the drag force, cells with aggressive phenotypes are influenced more by the DEP force and trap on posts while others flow through the chip unaffected. Utilizing single-cell trapping via cell-sized posts coupled with a drag-DEP force balance, we show that separation of similar cell subpopulations may be achieved, a result that was previously impossible with DEP alone. Separated subpopulations maintain high viability downstream, and remain in a native state, without fluorescent labeling. These cells can then be cultured to help select a therapy that kills aggressive subpopulations equally or better than the bulk of the tumor, mitigating resistance and recurrence.},
   keywords = {Animals
Cell Line, Tumor
*Cell Separation/instrumentation/methods
Computer Simulation
Electrophoresis, Microchip/*instrumentation/*methods
Equipment Design/instrumentation/methods
Feasibility Studies
Female
Humans
*Lab-On-A-Chip Devices
Mechanical Phenomena
Mice
Mice, Inbred C57BL
Microelectrodes
Models, Theoretical
Motion
Neoplasms/*pathology
Ovarian Neoplasms
Biophysics
Cell separation
Heterogeneity
Microfluidics
Tumor},
   ISSN = {0173-0835 (Print)
0173-0835},
   DOI = {10.1002/elps.201600530},
   year = {2017},
   type = {Journal Article}
}

A common problem with cancer treatment is the development of treatment resistance and tumor recurrence that result from treatments that kill most tumor cells yet leave behind aggressive cells to repopulate. Presented here is a microfluidic device that can be used to isolate tumor subpopulations to optimize treatment selection. Dielectrophoresis (DEP) is a phenomenon where particles are polarized by an electric field and move along the electric field gradient. Different cell subpopulations have different DEP responses depending on their bioelectrical phenotype, which, we hypothesize, correlate with aggressiveness. We have designed a microfluidic device in which a region containing posts locally distorts the electric field created by an AC voltage and forces cells toward the posts through DEP. This force is balanced with a simultaneous drag force from fluid motion that pulls cells away from the posts. We have shown that by adjusting the drag force, cells with aggressive phenotypes are influenced more by the DEP force and trap on posts while others flow through the chip unaffected. Utilizing single-cell trapping via cell-sized posts coupled with a drag-DEP force balance, we show that separation of similar cell subpopulations may be achieved, a result that was previously impossible with DEP alone. Separated subpopulations maintain high viability downstream, and remain in a native state, without fluorescent labeling. These cells can then be cultured to help select a therapy that kills aggressive subpopulations equally or better than the bulk of the tumor, mitigating resistance and recurrence.

@article{RN167,
   author = {Garcia, P. A. and Kos, B. and Rossmeisl, J. H., Jr. and Pavliha, D. and Miklavčič, D. and Davalos, R. V.},
   title = {Predictive therapeutic planning for irreversible electroporation treatment of spontaneous malignant glioma},
   journal = {Med Phys},
   volume = {44},
   number = {9},
   pages = {4968-4980},
   note = {2473-4209
Garcia, Paulo A
Kos, Bor
Rossmeisl, John H Jr
Pavliha, Denis
Miklavčič, Damijan
Davalos, Rafael V
Journal Article
United States
2017/06/09
Med Phys. 2017 Sep;44(9):4968-4980. doi: 10.1002/mp.12401. Epub 2017 Jul 25.},
   abstract = {PURPOSE: Irreversible electroporation (IRE) has been developed as a promising minimally invasive treatment to ablate spontaneous brain tumors with pulsed electric fields in canine patients. The purpose of the study is to determine the Peleg-Fermi parameters needed to incorporate pulse number and pulse duration into the therapeutic planning of IRE. METHODS: Seven canine patients were treated with IRE for spontaneous malignant glioma with MRI-based treatment planning. The treatment planning method consists of building patient-specific finite element models and using them to compute electric fields used in the IRE treatment. We evaluate the predictive power of tumor coverage with electric field alone vs. cell kill probability using radiographically confirmed clinical outcomes. RESULTS: Results of post-treatment diagnostic imaging, tumor biopsies, and neurological examinations indicated successful tumor ablation without significant direct neurotoxicity in six of the seven dogs. Objective tumor responses were seen in four (80%) of five dogs with quantifiable target lesions according to RANO criteria. Two dogs experienced survivals in excess of 1 yr, including one dog that resulted in complete response to IRE treatment for 5+ years to date. Tumor fraction exposed to electric field over 600 V/cm was between 0.08 and 0.73, while tumor fraction exposed to electric field over 300 V/cm was between 0.17 and 0.95. Probability of cell kill of ≥ 90% was found in tumor volume fractions between 0.21 and 0.99. CONCLUSIONS: We conclude that IRE is a safe and effective minimally invasive treatment for malignant glioma and can be predicted with the Peleg-Fermi cell kill probability function. A tumor coverage of ≥ 0.9 at a cell kill probability ≥ 90% can be used to guide IRE treatments of spontaneous malignant glioma based on the radiographically confirmed clinical outcomes achieved.},
   keywords = {Animals
Brain Neoplasms/*therapy
Dogs
*Electroporation
Glioma/*therapy
Magnetic Resonance Imaging
Treatment Outcome
brain tumor
minimally invasive
neurosurgery
pulsed electric fields
treatment planning},
   ISSN = {0094-2405},
   DOI = {10.1002/mp.12401},
   year = {2017},
   type = {Journal Article}
}

PURPOSE: Irreversible electroporation (IRE) has been developed as a promising minimally invasive treatment to ablate spontaneous brain tumors with pulsed electric fields in canine patients. The purpose of the study is to determine the Peleg-Fermi parameters needed to incorporate pulse number and pulse duration into the therapeutic planning of IRE. METHODS: Seven canine patients were treated with IRE for spontaneous malignant glioma with MRI-based treatment planning. The treatment planning method consists of building patient-specific finite element models and using them to compute electric fields used in the IRE treatment. We evaluate the predictive power of tumor coverage with electric field alone vs. cell kill probability using radiographically confirmed clinical outcomes. RESULTS: Results of post-treatment diagnostic imaging, tumor biopsies, and neurological examinations indicated successful tumor ablation without significant direct neurotoxicity in six of the seven dogs. Objective tumor responses were seen in four (80%) of five dogs with quantifiable target lesions according to RANO criteria. Two dogs experienced survivals in excess of 1 yr, including one dog that resulted in complete response to IRE treatment for 5+ years to date. Tumor fraction exposed to electric field over 600 V/cm was between 0.08 and 0.73, while tumor fraction exposed to electric field over 300 V/cm was between 0.17 and 0.95. Probability of cell kill of ≥ 90% was found in tumor volume fractions between 0.21 and 0.99. CONCLUSIONS: We conclude that IRE is a safe and effective minimally invasive treatment for malignant glioma and can be predicted with the Peleg-Fermi cell kill probability function. A tumor coverage of ≥ 0.9 at a cell kill probability ≥ 90% can be used to guide IRE treatments of spontaneous malignant glioma based on the radiographically confirmed clinical outcomes achieved.

@article{RN173,
   author = {Goswami, I. and Coutermarsh-Ott, S. and Morrison, R. G. and Allen, I. C. and Davalos, R. V. and Verbridge, S. S. and Bickford, L. R.},
   title = {Irreversible electroporation inhibits pro-cancer inflammatory signaling in triple negative breast cancer cells},
   journal = {Bioelectrochemistry},
   volume = {113},
   pages = {42-50},
   note = {1878-562x
Goswami, Ishan
Coutermarsh-Ott, Sheryl
Morrison, Ryan G
Allen, Irving C
Davalos, Rafael V
Verbridge, Scott S
Bickford, Lissett R
R03 DK105975/DK/NIDDK NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
T32 OD010430/OD/NIH HHS/United States
Journal Article
Netherlands
2016/10/04
Bioelectrochemistry. 2017 Feb;113:42-50. doi: 10.1016/j.bioelechem.2016.09.003. Epub 2016 Sep 25.},
   abstract = {Low-level electric fields have been demonstrated to induce spatial re-distribution of cell membrane receptors when applied for minutes or hours. However, there is limited literature on the influence on cell signaling with short transient high-amplitude pulses typically used in irreversible electroporation (IRE) for cancer treatment. Moreover, literature on signaling pertaining to immune cell trafficking after IRE is conflicting. We hypothesized that pulse parameters (field strength and exposure time) influence cell signaling and subsequently impact immune-cell trafficking. This hypothesis was tested in-vitro on triple negative breast cancer cells treated with IRE, where the effects of pulse parameters on key cell signaling factors were investigated. Importantly, real time PCR mRNA measurements and ELISA protein analyses revealed that thymic stromal lymphopoietin (TSLP) signaling was down regulated by electric field strengths above a critical threshold, irrespective of exposure times spanning those typically used clinically. Comparison with other treatments (thermal shock, chemical poration, kinase inhibitors) revealed that IRE has a unique effect on TSLP. Because TSLP signaling has been demonstrated to drive pro-cancerous immune cell phenotypes in breast and pancreatic cancers, our finding motivates further investigation into the potential use of IRE for induction of an anti-tumor immune response in vivo.},
   keywords = {Cell Death
Cytokines/metabolism
Electricity
*Electroporation
Humans
Inflammation/pathology
*Signal Transduction
Triple Negative Breast Neoplasms/*pathology
Thymic Stromal Lymphopoietin
Electroporation
Immunotherapy
Thymic stromal lymphopoietin (TSLP)
Triple negative breast cancer},
   ISSN = {1567-5394 (Print)
1567-5394},
   DOI = {10.1016/j.bioelechem.2016.09.003},
   year = {2017},
   type = {Journal Article}
}

Low-level electric fields have been demonstrated to induce spatial re-distribution of cell membrane receptors when applied for minutes or hours. However, there is limited literature on the influence on cell signaling with short transient high-amplitude pulses typically used in irreversible electroporation (IRE) for cancer treatment. Moreover, literature on signaling pertaining to immune cell trafficking after IRE is conflicting. We hypothesized that pulse parameters (field strength and exposure time) influence cell signaling and subsequently impact immune-cell trafficking. This hypothesis was tested in-vitro on triple negative breast cancer cells treated with IRE, where the effects of pulse parameters on key cell signaling factors were investigated. Importantly, real time PCR mRNA measurements and ELISA protein analyses revealed that thymic stromal lymphopoietin (TSLP) signaling was down regulated by electric field strengths above a critical threshold, irrespective of exposure times spanning those typically used clinically. Comparison with other treatments (thermal shock, chemical poration, kinase inhibitors) revealed that IRE has a unique effect on TSLP. Because TSLP signaling has been demonstrated to drive pro-cancerous immune cell phenotypes in breast and pancreatic cancers, our finding motivates further investigation into the potential use of IRE for induction of an anti-tumor immune response in vivo.

@article{RN165,
   author = {Ivey, J. W. and Latouche, E. L. and Richards, M. L. and Lesser, G. J. and Debinski, W. and Davalos, R. V. and Verbridge, S. S.},
   title = {Enhancing Irreversible Electroporation by Manipulating Cellular Biophysics with a Molecular Adjuvant},
   journal = {Biophys J},
   volume = {113},
   number = {2},
   pages = {472-480},
   note = {1542-0086
Ivey, Jill W
Latouche, Eduardo L
Richards, Megan L
Lesser, Glenn J
Debinski, Waldemar
Davalos, Rafael V
Verbridge, Scott S
P30 CA012197/CA/NCI NIH HHS/United States
R01 CA213423/CA/NCI NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
Journal Article
United States
2017/07/27
Biophys J. 2017 Jul 25;113(2):472-480. doi: 10.1016/j.bpj.2017.06.014.},
   abstract = {Pulsed electric fields applied to cells have been used as an invaluable research tool to enhance delivery of genes or other intracellular cargo, as well as for tumor treatment via electrochemotherapy or tissue ablation. These processes involve the buildup of charge across the cell membrane, with subsequent alteration of transmembrane potential that is a function of cell biophysics and geometry. For traditional electroporation parameters, larger cells experience a greater degree of membrane potential alteration. However, we have recently demonstrated that the nuclear/cytoplasm ratio (NCR), rather than cell size, is a key predictor of response for cells treated with high-frequency irreversible electroporation (IRE). In this study, we leverage a targeted molecular therapy, ephrinA1, known to markedly collapse the cytoplasm of cells expressing the EphA2 receptor, to investigate how biophysical cellular changes resulting from NCR manipulation affect the response to IRE at varying frequencies. We present evidence that the increase in the NCR mitigates the cell death response to conventional electroporation pulsed-electric fields (∼100 μs), consistent with the previously noted size dependence. However, this same molecular treatment enhanced the cell death response to high-frequency electric fields (∼1 μs). This finding demonstrates the importance of considering cellular biophysics and frequency-dependent effects in developing electroporation protocols, and our approach provides, to our knowledge, a novel and direct experimental methodology to quantify the relationship between cell morphology, pulse frequency, and electroporation response. Finally, this novel, to our knowledge, combinatorial approach may provide a paradigm to enhance in vivo tumor ablation through a molecular manipulation of cellular morphology before IRE application.},
   keywords = {Animals
Astrocytes/drug effects/pathology
Biomechanical Phenomena
Cell Death/drug effects
Cell Line, Tumor
Cell Size
Coculture Techniques
Collagen
Electromagnetic Fields
Electroporation/*methods
Ephrin-A1/*pharmacology
Finite Element Analysis
Glioma/drug therapy/pathology/therapy
Humans
Hydrogels
Membrane Potentials
Models, Biological
Molecular Targeted Therapy/*methods
Rats
Receptor, EphA2/metabolism},
   ISSN = {0006-3495 (Print)
0006-3495},
   DOI = {10.1016/j.bpj.2017.06.014},
   year = {2017},
   type = {Journal Article}
}

Pulsed electric fields applied to cells have been used as an invaluable research tool to enhance delivery of genes or other intracellular cargo, as well as for tumor treatment via electrochemotherapy or tissue ablation. These processes involve the buildup of charge across the cell membrane, with subsequent alteration of transmembrane potential that is a function of cell biophysics and geometry. For traditional electroporation parameters, larger cells experience a greater degree of membrane potential alteration. However, we have recently demonstrated that the nuclear/cytoplasm ratio (NCR), rather than cell size, is a key predictor of response for cells treated with high-frequency irreversible electroporation (IRE). In this study, we leverage a targeted molecular therapy, ephrinA1, known to markedly collapse the cytoplasm of cells expressing the EphA2 receptor, to investigate how biophysical cellular changes resulting from NCR manipulation affect the response to IRE at varying frequencies. We present evidence that the increase in the NCR mitigates the cell death response to conventional electroporation pulsed-electric fields (∼100 μs), consistent with the previously noted size dependence. However, this same molecular treatment enhanced the cell death response to high-frequency electric fields (∼1 μs). This finding demonstrates the importance of considering cellular biophysics and frequency-dependent effects in developing electroporation protocols, and our approach provides, to our knowledge, a novel and direct experimental methodology to quantify the relationship between cell morphology, pulse frequency, and electroporation response. Finally, this novel, to our knowledge, combinatorial approach may provide a paradigm to enhance in vivo tumor ablation through a molecular manipulation of cellular morphology before IRE application.

@article{RN171,
   author = {Latouche, E. L. and Sano, M. B. and Lorenzo, M. F. and Davalos, R. V. and Martin, R. C. G., 2nd},
   title = {Irreversible electroporation for the ablation of pancreatic malignancies: A patient-specific methodology},
   journal = {J Surg Oncol},
   volume = {115},
   number = {6},
   pages = {711-717},
   note = {1096-9098
Latouche, Eduardo L
Sano, Michael B
Lorenzo, Melvin F
Davalos, Rafael V
Martin, Robert C G 2nd
Journal Article
United States
2017/02/12
J Surg Oncol. 2017 May;115(6):711-717. doi: 10.1002/jso.24566. Epub 2017 Feb 10.},
   abstract = {BACKGROUND AND OBJECTIVES: Irreversible Electroporation (IRE) is a focal ablation technique highly attractive to surgical oncologists due to its non-thermal nature that allows for eradication of unresectable tumors in a minimally invasive procedure. In this study, our group sought to address the challenge of predicting the ablation volume with IRE for pancreatic procedures. METHODS: In compliance with HIPAA and hospital IRB approval, we established a pre-treatment planning methodology for IRE procedures in pancreas, which optimized treatment protocols for individual cases of locally advanced pancreatic cancer (LAPC). A new method for confirming treatment plans through intraoperative monitoring of tissue resistance was also proved feasible in three patients. RESULTS: Results from computational models showed good correlation with experimental data available in the literature. By implementing the proposed resistance measurement system 210 ± 26.1 (mean ± standard deviation) fewer pulses were delivered per electrode-pair. CONCLUSION: The proposed physics-based pre-treatment plan through finite element analysis and system for actively monitoring resistance changes can be paired to significantly reduce ablation times and risk of thermal effects during IRE procedures for LAPC.},
   keywords = {Ablation Techniques/*methods
Aged
Electroporation/*methods
Finite Element Analysis
Humans
Male
Models, Anatomic
Pancreatic Neoplasms/diagnostic imaging/*surgery
Precision Medicine/methods
Ire
impedance
pancreatic adenocarcinoma
real-time feedback
treatment planning},
   ISSN = {0022-4790},
   DOI = {10.1002/jso.24566},
   year = {2017},
   type = {Journal Article}
}

BACKGROUND AND OBJECTIVES: Irreversible Electroporation (IRE) is a focal ablation technique highly attractive to surgical oncologists due to its non-thermal nature that allows for eradication of unresectable tumors in a minimally invasive procedure. In this study, our group sought to address the challenge of predicting the ablation volume with IRE for pancreatic procedures. METHODS: In compliance with HIPAA and hospital IRB approval, we established a pre-treatment planning methodology for IRE procedures in pancreas, which optimized treatment protocols for individual cases of locally advanced pancreatic cancer (LAPC). A new method for confirming treatment plans through intraoperative monitoring of tissue resistance was also proved feasible in three patients. RESULTS: Results from computational models showed good correlation with experimental data available in the literature. By implementing the proposed resistance measurement system 210 ± 26.1 (mean ± standard deviation) fewer pulses were delivered per electrode-pair. CONCLUSION: The proposed physics-based pre-treatment plan through finite element analysis and system for actively monitoring resistance changes can be paired to significantly reduce ablation times and risk of thermal effects during IRE procedures for LAPC.

@inbook{RN162,
   author = {Lorenzo, M. F. and Arena, C. B. and Davalos, R. V.},
   title = {Maximizing Local Access to Therapeutic Deliveries in Glioblastoma. Part III: Irreversible Electroporation and High-Frequency Irreversible Electroporation for the Eradication of Glioblastoma},
   booktitle = {Glioblastoma},
   editor = {De Vleeschouwer, S.},
   publisher = {Codon Publications
Copyright: The Authors.},
   address = {Brisbane (AU)},
   note = {De Vleeschouwer, Steven
Lorenzo, Melvin F
Arena, Christopher B
Davalos, Rafael V
Review
Book Chapter
NBK469989 [bookaccession]},
   abstract = {Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Approximately 9180 primary GBM tumors are diagnosed in the United States each year, in which median survival is up to 16 months. GBM eludes and resists typical cancer treatments due to the presence of infiltrative cells beyond the solid tumor margin, heterogeneity within the tumor microenvironment, and protection from the blood–brain barrier. Conventional treatments for GBM, such as surgical resection, radiotherapy, and chemotherapy, have shown limited efficacy; therefore, alternate treatments are needed. Tumor chemoresistance and its proximity to critical structures make GBM a prime theoretical candidate for nonthermal ablation with irreversible electroporation (IRE) and high-frequency IRE (H-FIRE). IRE and H-FIRE are treatment modalities that utilize pulsed electric fields to permeabilize the cell membrane. Once the electric field magnitude exceeds a tissue-specific lethal threshold, cell death occurs. Benefits of IRE and H-FIRE therapy include, but are not limited to, the elimination of cytotoxic effects, sharp delineation from treated tissue and spared tissue, a nonthermal mechanism of ablation, and sparing of nerves and major blood vessels. Preclinical studies have confirmed the safety and efficacy of IRE and H-FIRE within their experimental scope. In this chapter, studies will be collected and information extrapolated to provide possible treatment regimens for use in high-grade gliomas, specifically in GBM.},
   DOI = {10.15586/codon.glioblastoma.2017.ch19},
   year = {2017},
   type = {Book Section}
}

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Approximately 9180 primary GBM tumors are diagnosed in the United States each year, in which median survival is up to 16 months. GBM eludes and resists typical cancer treatments due to the presence of infiltrative cells beyond the solid tumor margin, heterogeneity within the tumor microenvironment, and protection from the blood–brain barrier. Conventional treatments for GBM, such as surgical resection, radiotherapy, and chemotherapy, have shown limited efficacy; therefore, alternate treatments are needed. Tumor chemoresistance and its proximity to critical structures make GBM a prime theoretical candidate for nonthermal ablation with irreversible electroporation (IRE) and high-frequency IRE (H-FIRE). IRE and H-FIRE are treatment modalities that utilize pulsed electric fields to permeabilize the cell membrane. Once the electric field magnitude exceeds a tissue-specific lethal threshold, cell death occurs. Benefits of IRE and H-FIRE therapy include, but are not limited to, the elimination of cytotoxic effects, sharp delineation from treated tissue and spared tissue, a nonthermal mechanism of ablation, and sparing of nerves and major blood vessels. Preclinical studies have confirmed the safety and efficacy of IRE and H-FIRE within their experimental scope. In this chapter, studies will be collected and information extrapolated to provide possible treatment regimens for use in high-grade gliomas, specifically in GBM.

@article{RN163,
   author = {Mercadal, B. and Arena, C. B. and Davalos, R. V. and Ivorra, A.},
   title = {Avoiding nerve stimulation in irreversible electroporation: a numerical modeling study},
   journal = {Phys Med Biol},
   volume = {62},
   number = {20},
   pages = {8060-8079},
   note = {1361-6560
Mercadal, Borja
Arena, Christopher B
Davalos, Rafael V
Ivorra, Antoni
R01 CA213423/CA/NCI NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
Journal Article
England
2017/09/14
Phys Med Biol. 2017 Oct 4;62(20):8060-8079. doi: 10.1088/1361-6560/aa8c53.},
   abstract = {Electroporation based treatments consist in applying one or multiple high voltage pulses to the tissues to be treated. As an undesired side effect, these pulses cause electrical stimulation of excitable tissues such as nerves and muscles. This increases the complexity of the treatments and may pose a risk to the patient. To minimize electrical stimulation during electroporation based treatments, it has been proposed to replace the commonly used monopolar pulses by bursts of short bipolar pulses. In the present study, we have numerically analyzed the rationale for such approach. We have compared different pulsing protocols in terms of their electroporation efficacy and their capability of triggering action potentials in nerves. For that, we have developed a modeling framework that combines numerical models of nerve fibers and experimental data on irreversible electroporation. Our results indicate that, by replacing the conventional relatively long monopolar pulses by bursts of short bipolar pulses, it is possible to ablate a large tissue region without triggering action potentials in a nearby nerve. Our models indicate that this is possible because, as the pulse length of these bipolar pulses is reduced, the stimulation thresholds raise faster than the irreversible electroporation thresholds. We propose that this different dependence on the pulse length is due to the fact that transmembrane charging for nerve fibers is much slower than that of cells treated by electroporation because of their geometrical differences.},
   keywords = {Electric Stimulation/*adverse effects
Electroporation/*methods
Humans
*Models, Theoretical
Muscles/*radiation effects
Nerve Fibers/*radiation effects},
   ISSN = {0031-9155 (Print)
0031-9155},
   DOI = {10.1088/1361-6560/aa8c53},
   year = {2017},
   type = {Journal Article}
}

Electroporation based treatments consist in applying one or multiple high voltage pulses to the tissues to be treated. As an undesired side effect, these pulses cause electrical stimulation of excitable tissues such as nerves and muscles. This increases the complexity of the treatments and may pose a risk to the patient. To minimize electrical stimulation during electroporation based treatments, it has been proposed to replace the commonly used monopolar pulses by bursts of short bipolar pulses. In the present study, we have numerically analyzed the rationale for such approach. We have compared different pulsing protocols in terms of their electroporation efficacy and their capability of triggering action potentials in nerves. For that, we have developed a modeling framework that combines numerical models of nerve fibers and experimental data on irreversible electroporation. Our results indicate that, by replacing the conventional relatively long monopolar pulses by bursts of short bipolar pulses, it is possible to ablate a large tissue region without triggering action potentials in a nearby nerve. Our models indicate that this is possible because, as the pulse length of these bipolar pulses is reduced, the stimulation thresholds raise faster than the irreversible electroporation thresholds. We propose that this different dependence on the pulse length is due to the fact that transmembrane charging for nerve fibers is much slower than that of cells treated by electroporation because of their geometrical differences.

@article{RN166,
   author = {Miklovic, T. and Latouche, E. L. and DeWitt, M. R. and Davalos, R. V. and Sano, M. B.},
   title = {A Comprehensive Characterization of Parameters Affecting High-Frequency Irreversible Electroporation Lesions},
   journal = {Ann Biomed Eng},
   volume = {45},
   number = {11},
   pages = {2524-2534},
   note = {1573-9686
Miklovic, Tyler
Latouche, Eduardo L
DeWitt, Matthew R
Davalos, Rafael V
Sano, Michael B
Journal Article
United States
2017/07/20
Ann Biomed Eng. 2017 Nov;45(11):2524-2534. doi: 10.1007/s10439-017-1889-2. Epub 2017 Jul 18.},
   abstract = {Several focal therapies are being investigated clinically to treat tumors in which surgery is contraindicated. Many of these ablation techniques, such as radiofrequency ablation and microwave ablation, rely on thermal damage mechanisms which can put critical nerves or vasculature at risk. Irreversible electroporation (IRE) is a minimally invasive, non-thermal technique to destroy tumors. A series of short electric pulses create nanoscale defects in the cell membrane, eventually leading to cell death. Typical IRE protocols deliver a series of 50-100 µs monopolar pulses. High frequency IRE (H-FIRE) aims to replace these monopolar pulses with integrated bursts of 0.25-10 µs bipolar pulses. Here, we examine ablations created using a broad array of IRE and H-FIRE protocols in a potato tissue phantom model. Our results show that H-FIRE pulses require a higher energy dose to create equivalent lesions to standard IRE treatment protocols. We show that ablations in potato do not increase when more than 40 H-FIRE bursts are delivered. These results show that H-FIRE treatment protocols can be optimized to produce clinically relevant lesions while maintaining the benefits of a non-thermal ablation technique.},
   keywords = {Cell Death
Electroporation/*methods
Finite Element Analysis
Phantoms, Imaging
Solanum tuberosum
Focal ablation
H-fire
Non-thermal therapy
Tissue phantom},
   ISSN = {0090-6964},
   DOI = {10.1007/s10439-017-1889-2},
   year = {2017},
   type = {Journal Article}
}

Several focal therapies are being investigated clinically to treat tumors in which surgery is contraindicated. Many of these ablation techniques, such as radiofrequency ablation and microwave ablation, rely on thermal damage mechanisms which can put critical nerves or vasculature at risk. Irreversible electroporation (IRE) is a minimally invasive, non-thermal technique to destroy tumors. A series of short electric pulses create nanoscale defects in the cell membrane, eventually leading to cell death. Typical IRE protocols deliver a series of 50-100 µs monopolar pulses. High frequency IRE (H-FIRE) aims to replace these monopolar pulses with integrated bursts of 0.25-10 µs bipolar pulses. Here, we examine ablations created using a broad array of IRE and H-FIRE protocols in a potato tissue phantom model. Our results show that H-FIRE pulses require a higher energy dose to create equivalent lesions to standard IRE treatment protocols. We show that ablations in potato do not increase when more than 40 H-FIRE bursts are delivered. These results show that H-FIRE treatment protocols can be optimized to produce clinically relevant lesions while maintaining the benefits of a non-thermal ablation technique.

@article{RN169,
   author = {Rossmeisl, J. H. and Hall-Manning, K. and Robertson, J. L. and King, J. N. and Davalos, R. V. and Debinski, W. and Elankumaran, S.},
   title = {Expression and activity of the urokinase plasminogen activator system in canine primary brain tumors},
   journal = {Onco Targets Ther},
   volume = {10},
   pages = {2077-2085},
   note = {1178-6930
Rossmeisl, John H
Hall-Manning, Kelli
Robertson, John L
King, Jamie N
Davalos, Rafael V
Debinski, Waldemar
Elankumaran, Subbiah
R01 CA139099/CA/NCI NIH HHS/United States
R21 AI070528/AI/NIAID NIH HHS/United States
Journal Article
New Zealand
2017/04/27
Onco Targets Ther. 2017 Apr 12;10:2077-2085. doi: 10.2147/OTT.S132964. eCollection 2017.},
   abstract = {BACKGROUND: The expression of the urokinase plasminogen activator receptor (uPAR), a glycosylphosphatidylinositol-anchored protein family member, and the activity of its ligand, urokinase-type plasminogen activator (uPA), have been associated with the invasive and metastatic potentials of a variety of human brain tumors through their regulation of extracellular matrix degradation. Domesticated dogs develop naturally occurring brain tumors that share many clinical, phenotypic, molecular, and genetic features with their human counterparts, which has prompted the use of the dogs with spontaneous brain tumors as models to expedite the translation of novel brain tumor therapeutics to humans. There is currently little known regarding the role of the uPA system in canine brain tumorigenesis. The objective of this study was to characterize the expression of uPAR and the activity of uPA in canine brain tumors as justification for the development of uPAR-targeted brain tumor therapeutics in dogs. METHODS: We investigated the expression of uPAR in 37 primary canine brain tumors using immunohistochemistry, Western blotting, real-time quantitative polymerase chain reaction analyses, and by the assay of the activity of uPA using casein-plasminogen zymography. RESULTS: Expression of uPAR was observed in multiple tumoral microenvironmental niches, including neoplastic cells, stroma, and the vasculature of canine brain tumors. Relative to normal brain tissues, uPAR protein and mRNA expression were significantly greater in canine meningiomas, gliomas, and choroid plexus tumors. Increased activity of uPA was documented in all tumor types. CONCLUSIONS: uPAR is overexpressed and uPA activity increased in canine meningiomas, gliomas, and choroid plexus tumors. This study illustrates the potential of uPAR/uPA molecularly targeted approaches for canine brain tumor therapeutics and reinforces the translational significance of canines with spontaneous brain tumors as models for human disease.},
   keywords = {animal model
brain tumor
dog
glioma
meningioma
neuro-oncology
protease},
   ISSN = {1178-6930 (Print)
1178-6930},
   DOI = {10.2147/ott.S132964},
   year = {2017},
   type = {Journal Article}
}

BACKGROUND: The expression of the urokinase plasminogen activator receptor (uPAR), a glycosylphosphatidylinositol-anchored protein family member, and the activity of its ligand, urokinase-type plasminogen activator (uPA), have been associated with the invasive and metastatic potentials of a variety of human brain tumors through their regulation of extracellular matrix degradation. Domesticated dogs develop naturally occurring brain tumors that share many clinical, phenotypic, molecular, and genetic features with their human counterparts, which has prompted the use of the dogs with spontaneous brain tumors as models to expedite the translation of novel brain tumor therapeutics to humans. There is currently little known regarding the role of the uPA system in canine brain tumorigenesis. The objective of this study was to characterize the expression of uPAR and the activity of uPA in canine brain tumors as justification for the development of uPAR-targeted brain tumor therapeutics in dogs. METHODS: We investigated the expression of uPAR in 37 primary canine brain tumors using immunohistochemistry, Western blotting, real-time quantitative polymerase chain reaction analyses, and by the assay of the activity of uPA using casein-plasminogen zymography. RESULTS: Expression of uPAR was observed in multiple tumoral microenvironmental niches, including neoplastic cells, stroma, and the vasculature of canine brain tumors. Relative to normal brain tissues, uPAR protein and mRNA expression were significantly greater in canine meningiomas, gliomas, and choroid plexus tumors. Increased activity of uPA was documented in all tumor types. CONCLUSIONS: uPAR is overexpressed and uPA activity increased in canine meningiomas, gliomas, and choroid plexus tumors. This study illustrates the potential of uPAR/uPA molecularly targeted approaches for canine brain tumor therapeutics and reinforces the translational significance of canines with spontaneous brain tumors as models for human disease.

@article{RN168,
   author = {Siddiqui, I. A. and Kirks, R. C. and Latouche, E. L. and DeWitt, M. R. and Swet, J. H. and Baker, E. H. and Vrochides, D. and Iannitti, D. A. and Davalos, R. V. and McKillop, I. H.},
   title = {High-Frequency Irreversible Electroporation: Safety and Efficacy of Next-Generation Irreversible Electroporation Adjacent to Critical Hepatic Structures},
   journal = {Surg Innov},
   volume = {24},
   number = {3},
   pages = {276-283},
   note = {1553-3514
Siddiqui, Imran A
Kirks, Russell C
Latouche, Eduardo L
DeWitt, Matthew R
Swet, Jacob H
Baker, Erin H
Vrochides, Dionisios
Iannitti, David A
Davalos, Rafael V
McKillop, Iain H
Journal Article
United States
2017/05/12
Surg Innov. 2017 Jun;24(3):276-283. doi: 10.1177/1553350617692202. Epub 2017 Feb 1.},
   abstract = {Irreversible electroporation (IRE) is a nonthermal ablation modality employed to induce in situ tissue-cell death. This study sought to evaluate the efficacy of a novel high-frequency IRE (H-FIRE) system to perform hepatic ablations across, or adjacent to, critical vascular and biliary structures. Using ultrasound guidance H-FIRE electrodes were placed across, or adjacent to, portal pedicels, hepatic veins, or the gall bladder in a porcine model. H-FIRE pulses were delivered (2250 V, 2-5-2 pulse configuration) in the absence of cardiac synchronization or intraoperative paralytics. Six hours after H-FIRE the liver was resected and analyzed. Nine ablations were performed in 3 separate experimental groups (major vessels straddled by electrodes, electrodes placed adjacent to major vessels, electrodes placed adjacent to gall bladder). Average ablation time was 290 ± 63 seconds. No electrocardiogram abnormalities or changes in vital signs were observed during H-FIRE. At necropsy, no vascular damage, coagulated-thermally desiccated blood vessels, or perforated biliary structures were noted. Histologically, H-FIRE demonstrated effective tissue ablation and uniform induction of apoptotic cell death in the parenchyma independent of vascular or biliary structure location. Detailed microscopic analysis revealed minor endothelial damage within areas subjected to H-FIRE, particularly in regions proximal to electrode insertion. These data indicate H-FIRE is a novel means to perform rapid, reproducible IRE in liver tissue while preserving gross vascular/biliary architecture. These characteristics raise the potential for long-term survival studies to test the viability of this technology toward clinical use to target tumors not amenable to thermal ablation or resection.},
   keywords = {Ablation Techniques/*methods
Animals
Apoptosis
Biomedical Engineering
Electroporation/*methods
Female
Histocytochemistry
Liver/cytology/diagnostic imaging/*surgery
Liver Neoplasms
Surgery, Computer-Assisted/methods
Swine
image-guided surgery
surgical oncology},
   ISSN = {1553-3506},
   DOI = {10.1177/1553350617692202},
   year = {2017},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a nonthermal ablation modality employed to induce in situ tissue-cell death. This study sought to evaluate the efficacy of a novel high-frequency IRE (H-FIRE) system to perform hepatic ablations across, or adjacent to, critical vascular and biliary structures. Using ultrasound guidance H-FIRE electrodes were placed across, or adjacent to, portal pedicels, hepatic veins, or the gall bladder in a porcine model. H-FIRE pulses were delivered (2250 V, 2-5-2 pulse configuration) in the absence of cardiac synchronization or intraoperative paralytics. Six hours after H-FIRE the liver was resected and analyzed. Nine ablations were performed in 3 separate experimental groups (major vessels straddled by electrodes, electrodes placed adjacent to major vessels, electrodes placed adjacent to gall bladder). Average ablation time was 290 ± 63 seconds. No electrocardiogram abnormalities or changes in vital signs were observed during H-FIRE. At necropsy, no vascular damage, coagulated-thermally desiccated blood vessels, or perforated biliary structures were noted. Histologically, H-FIRE demonstrated effective tissue ablation and uniform induction of apoptotic cell death in the parenchyma independent of vascular or biliary structure location. Detailed microscopic analysis revealed minor endothelial damage within areas subjected to H-FIRE, particularly in regions proximal to electrode insertion. These data indicate H-FIRE is a novel means to perform rapid, reproducible IRE in liver tissue while preserving gross vascular/biliary architecture. These characteristics raise the potential for long-term survival studies to test the viability of this technology toward clinical use to target tumors not amenable to thermal ablation or resection.

@article{RN164,
   author = {Wasson, E. M. and Ivey, J. W. and Verbridge, S. S. and Davalos, R. V.},
   title = {The Feasibility of Enhancing Susceptibility of Glioblastoma Cells to IRE Using a Calcium Adjuvant},
   journal = {Ann Biomed Eng},
   volume = {45},
   number = {11},
   pages = {2535-2547},
   note = {1573-9686
Wasson, Elisa M
Orcid: 0000-0002-3263-2403
Ivey, Jill W
Verbridge, Scott S
Davalos, Rafael V
R01 CA213423/CA/NCI NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
Journal Article
United States
2017/08/30
Ann Biomed Eng. 2017 Nov;45(11):2535-2547. doi: 10.1007/s10439-017-1905-6. Epub 2017 Aug 28.},
   abstract = {Irreversible electroporation (IRE) is a cellular ablation method used to treat a variety of cancers. IRE works by exposing tissues to pulsed electric fields which cause cell membrane disruption. Cells exposed to lower energies become temporarily permeable while greater energy exposure results in cell death. For IRE to be used safely in the brain, methods are needed to extend the area of ablation without increasing applied voltage, and thus, thermal damage. We present evidence that IRE used with adjuvant calcium (5 mM CaCl(2)) results in a nearly twofold increase in ablation area in vitro compared to IRE alone. Adjuvant 5 mM CaCl(2) induces death in cells reversibly electroporated by IRE, thereby lowering the electric field thresholds required for cell death to nearly half that of IRE alone. The calcium-induced death response of reversibly electroporated cells is confirmed by electrochemotherapy pulses which also induced cell death with calcium but not without. These findings, combined with our numerical modeling, suggest the ability to ablate up to 3.2× larger volumes of tissue in vivo when combining IRE and calcium. The ability to ablate a larger volume with lowered energies would improve the efficacy and safety of IRE therapy.},
   keywords = {*Ablation Techniques
Adjuvants, Pharmaceutic/*pharmacology
Brain Neoplasms/therapy
Calcium Chloride/*pharmacology
Cell Line, Tumor
Collagen
*Electroporation
Glioblastoma/therapy
Humans
Models, Theoretical
Ablation volume
Brain cancer
Combined therapy
Electrochemotherapy
Finite element modeling
Irreversible electroporation},
   ISSN = {0090-6964 (Print)
0090-6964},
   DOI = {10.1007/s10439-017-1905-6},
   year = {2017},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a cellular ablation method used to treat a variety of cancers. IRE works by exposing tissues to pulsed electric fields which cause cell membrane disruption. Cells exposed to lower energies become temporarily permeable while greater energy exposure results in cell death. For IRE to be used safely in the brain, methods are needed to extend the area of ablation without increasing applied voltage, and thus, thermal damage. We present evidence that IRE used with adjuvant calcium (5 mM CaCl(2)) results in a nearly twofold increase in ablation area in vitro compared to IRE alone. Adjuvant 5 mM CaCl(2) induces death in cells reversibly electroporated by IRE, thereby lowering the electric field thresholds required for cell death to nearly half that of IRE alone. The calcium-induced death response of reversibly electroporated cells is confirmed by electrochemotherapy pulses which also induced cell death with calcium but not without. These findings, combined with our numerical modeling, suggest the ability to ablate up to 3.2× larger volumes of tissue in vivo when combining IRE and calcium. The ability to ablate a larger volume with lowered energies would improve the efficacy and safety of IRE therapy.

@article{RN174,
   author = {Bhonsle, S. and Bonakdar, M. and Neal, R. E., 2nd and Aardema, C. and Robertson, J. L. and Howarth, J. and Kavnoudias, H. and Thomson, K. R. and Goldberg, S. N. and Davalos, R. V.},
   title = {Characterization of Irreversible Electroporation Ablation with a Validated Perfused Organ Model},
   journal = {J Vasc Interv Radiol},
   volume = {27},
   number = {12},
   pages = {1913-1922.e2},
   note = {1535-7732
Bhonsle, Suyashree
Bonakdar, Mohammad
Neal, Robert E 2nd
Aardema, Charles
Robertson, John L
Howarth, Jonathon
Kavnoudias, Helen
Thomson, Kenneth R
Goldberg, S Nahum
Davalos, Rafael V
Comparative Study
Journal Article
Validation Study
United States
2016/09/25
J Vasc Interv Radiol. 2016 Dec;27(12):1913-1922.e2. doi: 10.1016/j.jvir.2016.07.012. Epub 2016 Sep 21.},
   abstract = {PURPOSE: To develop and validate a perfused organ model for characterizing ablations for irreversible electroporation (IRE)-based therapies. MATERIALS AND METHODS: Eight excised porcine livers were mechanically perfused with a modified phosphate-buffered saline solution to maintain viability during IRE ablation. IRE pulses were delivered using 2 monopolar electrodes over a range of parameters, including voltage (1,875-3,000 V), pulse length (70-100 µsec), number of pulses (50-600), electrode exposure (1.0-2.0 cm), and electrode spacing (1.5-2.0 cm). Organs were dissected, and treatment zones were stained with triphenyl tetrazolium chloride to demonstrate viability and highlight the area of ablation. Results were compared with 17 in vivo ablations performed in canine livers and 35 previously published ablations performed in porcine livers. RESULTS: Ablation dimensions in the perfused model correlated well with corresponding in vivo ablations (R(2) = 0.9098) with a 95% confidence interval of < 2.2 mm. Additionally, the validated perfused model showed that the IRE ablation zone grew logarithmically with increasing pulse numbers, showing small difference in ablation size over 200-600 pulses (3.2 mm ± 3.8 width and 5.2 mm ± 3.9 height). CONCLUSIONS: The perfused organ model provides an alternative to animal trials for investigation of IRE treatments. It may have an important role in the future development of new devices, algorithms, and techniques for this therapy.},
   keywords = {*Ablation Techniques/adverse effects/instrumentation
Animals
Dogs
Electrodes
*Electroporation/instrumentation
Equipment Design
In Vitro Techniques
Linear Models
Liver/pathology/*surgery
Male
*Perfusion
Species Specificity
Swine
Tissue Survival},
   ISSN = {1051-0443},
   DOI = {10.1016/j.jvir.2016.07.012},
   year = {2016},
   type = {Journal Article}
}

PURPOSE: To develop and validate a perfused organ model for characterizing ablations for irreversible electroporation (IRE)-based therapies. MATERIALS AND METHODS: Eight excised porcine livers were mechanically perfused with a modified phosphate-buffered saline solution to maintain viability during IRE ablation. IRE pulses were delivered using 2 monopolar electrodes over a range of parameters, including voltage (1,875-3,000 V), pulse length (70-100 µsec), number of pulses (50-600), electrode exposure (1.0-2.0 cm), and electrode spacing (1.5-2.0 cm). Organs were dissected, and treatment zones were stained with triphenyl tetrazolium chloride to demonstrate viability and highlight the area of ablation. Results were compared with 17 in vivo ablations performed in canine livers and 35 previously published ablations performed in porcine livers. RESULTS: Ablation dimensions in the perfused model correlated well with corresponding in vivo ablations (R(2) = 0.9098) with a 95% confidence interval of < 2.2 mm. Additionally, the validated perfused model showed that the IRE ablation zone grew logarithmically with increasing pulse numbers, showing small difference in ablation size over 200-600 pulses (3.2 mm ± 3.8 width and 5.2 mm ± 3.9 height). CONCLUSIONS: The perfused organ model provides an alternative to animal trials for investigation of IRE treatments. It may have an important role in the future development of new devices, algorithms, and techniques for this therapy.

@article{RN179,
   author = {Bonakdar, M. and Wasson, E. M. and Lee, Y. W. and Davalos, R. V.},
   title = {Electroporation of Brain Endothelial Cells on Chip toward Permeabilizing the Blood-Brain Barrier},
   journal = {Biophys J},
   volume = {110},
   number = {2},
   pages = {503-513},
   note = {1542-0086
Bonakdar, Mohammad
Wasson, Elisa M
Lee, Yong W
Davalos, Rafael V
R21 CA173092/CA/NCI NIH HHS/United States
5R21 CA173092-01/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2016/01/21
Biophys J. 2016 Jan 19;110(2):503-513. doi: 10.1016/j.bpj.2015.11.3517.},
   abstract = {The blood-brain barrier, mainly composed of brain microvascular endothelial cells, poses an obstacle to drug delivery to the brain. Controlled permeabilization of the constituent brain endothelial cells can result in overcoming this barrier and increasing transcellular transport across it. Electroporation is a biophysical phenomenon that has shown potential in permeabilizing and overcoming this barrier. In this study we developed a microengineered in vitro model to characterize the permeabilization of adhered brain endothelial cells to large molecules in response to applied pulsed electric fields. We found the distribution of affected cells by reversible and irreversible electroporation, and quantified the uptaken amount of naturally impermeable molecules into the cells as a result of applied pulse magnitude and number of pulses. We achieved 81 ± 1.7% (N = 6) electroporated cells with 17 ± 8% (N = 5) cell death using an electric-field magnitude of ∼580 V/cm and 10 pulses. Our results provide the proper range for applied electric-field intensity and number of pulses for safe permeabilization without significantly compromising cell viability. Our results demonstrate that it is possible to permeabilize the endothelial cells of the BBB in a controlled manner, therefore lending to the feasibility of using pulsed electric fields to increase drug transport across the BBB through the transcellular pathway.},
   keywords = {Animals
Blood-Brain Barrier/*metabolism
*Capillary Permeability
Cell Line
Electroporation/instrumentation/*methods
Endothelial Cells/*metabolism
Mice
Microfluidics/instrumentation/methods},
   ISSN = {0006-3495 (Print)
0006-3495},
   DOI = {10.1016/j.bpj.2015.11.3517},
   year = {2016},
   type = {Journal Article}
}

The blood-brain barrier, mainly composed of brain microvascular endothelial cells, poses an obstacle to drug delivery to the brain. Controlled permeabilization of the constituent brain endothelial cells can result in overcoming this barrier and increasing transcellular transport across it. Electroporation is a biophysical phenomenon that has shown potential in permeabilizing and overcoming this barrier. In this study we developed a microengineered in vitro model to characterize the permeabilization of adhered brain endothelial cells to large molecules in response to applied pulsed electric fields. We found the distribution of affected cells by reversible and irreversible electroporation, and quantified the uptaken amount of naturally impermeable molecules into the cells as a result of applied pulse magnitude and number of pulses. We achieved 81 ± 1.7% (N = 6) electroporated cells with 17 ± 8% (N = 5) cell death using an electric-field magnitude of ∼580 V/cm and 10 pulses. Our results provide the proper range for applied electric-field intensity and number of pulses for safe permeabilization without significantly compromising cell viability. Our results demonstrate that it is possible to permeabilize the endothelial cells of the BBB in a controlled manner, therefore lending to the feasibility of using pulsed electric fields to increase drug transport across the BBB through the transcellular pathway.

@article{RN178,
   author = {Čemažar, J. and Douglas, T. A. and Schmelz, E. M. and Davalos, R. V.},
   title = {Enhanced contactless dielectrophoresis enrichment and isolation platform via cell-scale microstructures},
   journal = {Biomicrofluidics},
   volume = {10},
   number = {1},
   pages = {014109},
   note = {1932-1058
Čemažar, Jaka
Douglas, Temple A
Schmelz, Eva M
Davalos, Rafael V
R21 CA173092/CA/NCI NIH HHS/United States
Journal Article
United States
2016/02/10
Biomicrofluidics. 2016 Jan 19;10(1):014109. doi: 10.1063/1.4939947. eCollection 2016 Jan.},
   abstract = {We designed a new microfluidic device that uses pillars on the same order as the diameter of a cell (20 μm) to isolate and enrich rare cell samples from background. These cell-scale microstructures improve viability, trapping efficiency, and throughput while reducing pearl chaining. The area where cells trap on each pillar is small, such that only one or two cells trap while fluid flow carries away excess cells. We employed contactless dielectrophoresis in which a thin PDMS membrane separates the cell suspension from the electrodes, improving cell viability for off-chip collection and analysis. We compared viability and trapping efficiency of a highly aggressive Mouse Ovarian Surface Epithelial (MOSE) cell line in this 20 μm pillar device to measurements in an earlier device with the same layout but pillars of 100 μm diameter. We found that MOSE cells in the new device with 20 μm pillars had higher viability at 350 VRMS, 30 kHz, and 1.2 ml/h (control 77%, untrapped 71%, trapped 81%) than in the previous generation device (untrapped 47%, trapped 42%). The new device can trap up to 6 times more cells under the same conditions. Our new device can sort cells with a high flow rate of 2.2 ml/h and throughput of a few million cells per hour while maintaining a viable population of cells for off-chip analysis. By using the device to separate subpopulations of tumor cells while maintaining their viability at large sample sizes, this technology can be used in developing personalized treatments that target the most aggressive cancerous cells.},
   ISSN = {1932-1058 (Print)
1932-1058},
   DOI = {10.1063/1.4939947},
   year = {2016},
   type = {Journal Article}
}

We designed a new microfluidic device that uses pillars on the same order as the diameter of a cell (20 μm) to isolate and enrich rare cell samples from background. These cell-scale microstructures improve viability, trapping efficiency, and throughput while reducing pearl chaining. The area where cells trap on each pillar is small, such that only one or two cells trap while fluid flow carries away excess cells. We employed contactless dielectrophoresis in which a thin PDMS membrane separates the cell suspension from the electrodes, improving cell viability for off-chip collection and analysis. We compared viability and trapping efficiency of a highly aggressive Mouse Ovarian Surface Epithelial (MOSE) cell line in this 20 μm pillar device to measurements in an earlier device with the same layout but pillars of 100 μm diameter. We found that MOSE cells in the new device with 20 μm pillars had higher viability at 350 VRMS, 30 kHz, and 1.2 ml/h (control 77%, untrapped 71%, trapped 81%) than in the previous generation device (untrapped 47%, trapped 42%). The new device can trap up to 6 times more cells under the same conditions. Our new device can sort cells with a high flow rate of 2.2 ml/h and throughput of a few million cells per hour while maintaining a viable population of cells for off-chip analysis. By using the device to separate subpopulations of tumor cells while maintaining their viability at large sample sizes, this technology can be used in developing personalized treatments that target the most aggressive cancerous cells.

@article{RN177,
   author = {George, S. A. and Bonakdar, M. and Zeitz, M. and Davalos, R. V. and Smyth, J. W. and Poelzing, S.},
   title = {Extracellular sodium dependence of the conduction velocity-calcium relationship: evidence of ephaptic self-attenuation},
   journal = {Am J Physiol Heart Circ Physiol},
   volume = {310},
   number = {9},
   pages = {H1129-39},
   note = {1522-1539
George, Sharon A
Bonakdar, Mohammad
Zeitz, Michael
Davalos, Rafael V
Smyth, James W
Poelzing, Steven
R01 HL102298/HL/NHLBI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2016/03/06
Am J Physiol Heart Circ Physiol. 2016 May 1;310(9):H1129-39. doi: 10.1152/ajpheart.00857.2015. Epub 2016 Mar 4.},
   abstract = {Our laboratory previously demonstrated that perfusate sodium and potassium concentrations can modulate cardiac conduction velocity (CV) consistent with theoretical predictions of ephaptic coupling (EpC). EpC depends on the ionic currents and intercellular separation in sodium channel rich intercalated disk microdomains like the perinexus. We suggested that perinexal width (WP) correlates with changes in extracellular calcium ([Ca(2+)]o). Here, we test the hypothesis that increasing [Ca(2+)]o reduces WP and increases CV. Mathematical models of EpC also predict that reducing WP can reduce sodium driving force and CV by self-attenuation. Therefore, we further hypothesized that reducing WP and extracellular sodium ([Na(+)]o) will reduce CV consistent with ephaptic self-attenuation. Transmission electron microscopy revealed that increasing [Ca(2+)]o (1 to 3.4 mM) significantly decreased WP Optically mapping wild-type (WT) (100% Cx43) mouse hearts demonstrated that increasing [Ca(2+)]o increases transverse CV during normonatremia (147.3 mM), but slows transverse CV during hyponatremia (120 mM). Additionally, CV in heterozygous (∼50% Cx43) hearts was more sensitive to changes in [Ca(2+)]o relative to WT during normonatremia. During hyponatremia, CV slowed in both WT and heterozygous hearts to the same extent. Importantly, neither [Ca(2+)]o nor [Na(+)]o altered Cx43 expression or phosphorylation determined by Western blotting, or gap junctional resistance determined by electrical impedance spectroscopy. Narrowing WP, by increasing [Ca(2+)]o, increases CV consistent with enhanced EpC between myocytes. Interestingly, during hyponatremia, reducing WP slowed CV, consistent with theoretical predictions of ephaptic self-attenuation. This study suggests that serum ion concentrations may be an important determinant of cardiac disease expression.},
   keywords = {*Action Potentials
Animals
Calcium/*metabolism
*Calcium Signaling
*Cell Communication
Computer Simulation
Connexin 43/deficiency/genetics
Dielectric Spectroscopy
Electric Impedance
Gap Junctions/metabolism
Genotype
Hyponatremia/blood/physiopathology
Isolated Heart Preparation
Kinetics
Mice, Inbred C57BL
Mice, Knockout
Microscopy, Electron, Transmission
*Models, Cardiovascular
Myocytes, Cardiac/*metabolism/ultrastructure
Phenotype
Sodium/*metabolism
Voltage-Sensitive Dye Imaging
calcium
conduction
ephaptic coupling
ion concentration
sodium},
   ISSN = {0363-6135 (Print)
0363-6135},
   DOI = {10.1152/ajpheart.00857.2015},
   year = {2016},
   type = {Journal Article}
}

Our laboratory previously demonstrated that perfusate sodium and potassium concentrations can modulate cardiac conduction velocity (CV) consistent with theoretical predictions of ephaptic coupling (EpC). EpC depends on the ionic currents and intercellular separation in sodium channel rich intercalated disk microdomains like the perinexus. We suggested that perinexal width (WP) correlates with changes in extracellular calcium ([Ca(2+)]o). Here, we test the hypothesis that increasing [Ca(2+)]o reduces WP and increases CV. Mathematical models of EpC also predict that reducing WP can reduce sodium driving force and CV by self-attenuation. Therefore, we further hypothesized that reducing WP and extracellular sodium ([Na(+)]o) will reduce CV consistent with ephaptic self-attenuation. Transmission electron microscopy revealed that increasing [Ca(2+)]o (1 to 3.4 mM) significantly decreased WP Optically mapping wild-type (WT) (100% Cx43) mouse hearts demonstrated that increasing [Ca(2+)]o increases transverse CV during normonatremia (147.3 mM), but slows transverse CV during hyponatremia (120 mM). Additionally, CV in heterozygous (∼50% Cx43) hearts was more sensitive to changes in [Ca(2+)]o relative to WT during normonatremia. During hyponatremia, CV slowed in both WT and heterozygous hearts to the same extent. Importantly, neither [Ca(2+)]o nor [Na(+)]o altered Cx43 expression or phosphorylation determined by Western blotting, or gap junctional resistance determined by electrical impedance spectroscopy. Narrowing WP, by increasing [Ca(2+)]o, increases CV consistent with enhanced EpC between myocytes. Interestingly, during hyponatremia, reducing WP slowed CV, consistent with theoretical predictions of ephaptic self-attenuation. This study suggests that serum ion concentrations may be an important determinant of cardiac disease expression.

@article{RN180,
   author = {Ivey, J. W. and Bonakdar, M. and Kanitkar, A. and Davalos, R. V. and Verbridge, S. S.},
   title = {Improving cancer therapies by targeting the physical and chemical hallmarks of the tumor microenvironment},
   journal = {Cancer Lett},
   volume = {380},
   number = {1},
   pages = {330-9},
   note = {1872-7980
Ivey, Jill W
Bonakdar, Mohammad
Kanitkar, Akanksha
Davalos, Rafael V
Verbridge, Scott S
R21 CA173092/CA/NCI NIH HHS/United States
R21 CA192042/CA/NCI NIH HHS/United States
R21 EB019123/EB/NIBIB NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Review
Ireland
2016/01/03
Cancer Lett. 2016 Sep 28;380(1):330-9. doi: 10.1016/j.canlet.2015.12.019. Epub 2015 Dec 24.},
   abstract = {Tumors are highly heterogeneous at the patient, tissue, cellular, and molecular levels. This multi-scale heterogeneity poses significant challenges for effective therapies, which ideally must not only distinguish between tumorous and healthy tissue, but also fully address the wide variety of tumorous sub-clones. Commonly used therapies either leverage a biological phenotype of cancer cells (e.g. high rate of proliferation) or indiscriminately kill all the cells present in a targeted volume. Tumor microenvironment (TME) targeting represents a promising therapeutic direction, because a number of TME hallmarks are conserved across different tumor types, despite the underlying genetic heterogeneity. Historically, TME targeting has largely focused on the cells that support tumor growth (e.g. vascular endothelial cells). However, by viewing the intrinsic physical and chemical alterations in the TME as additional therapeutic opportunities rather than barriers, a new class of TME-inspired treatments has great promise to complement or replace existing therapeutic strategies. In this review we summarize the physical and chemical hallmarks of the TME, and discuss how these tumor characteristics either currently are, or may ultimately be targeted to improve cancer therapies.},
   keywords = {*Ablation Techniques/methods
Animals
Antineoplastic Agents/*administration & dosage
Drug Carriers
*Drug Delivery Systems/methods
Drug Resistance, Neoplasm
Humans
Hydrogen-Ion Concentration
Neoplasms/metabolism/pathology/*therapy
Tumor Hypoxia
*Tumor Microenvironment
Chemcical tumor microenvironment
Electroporation therapy
Physical tumor microenvironment
Tumor microenvironment targeting},
   ISSN = {0304-3835 (Print)
0304-3835},
   DOI = {10.1016/j.canlet.2015.12.019},
   year = {2016},
   type = {Journal Article}
}

Tumors are highly heterogeneous at the patient, tissue, cellular, and molecular levels. This multi-scale heterogeneity poses significant challenges for effective therapies, which ideally must not only distinguish between tumorous and healthy tissue, but also fully address the wide variety of tumorous sub-clones. Commonly used therapies either leverage a biological phenotype of cancer cells (e.g. high rate of proliferation) or indiscriminately kill all the cells present in a targeted volume. Tumor microenvironment (TME) targeting represents a promising therapeutic direction, because a number of TME hallmarks are conserved across different tumor types, despite the underlying genetic heterogeneity. Historically, TME targeting has largely focused on the cells that support tumor growth (e.g. vascular endothelial cells). However, by viewing the intrinsic physical and chemical alterations in the TME as additional therapeutic opportunities rather than barriers, a new class of TME-inspired treatments has great promise to complement or replace existing therapeutic strategies. In this review we summarize the physical and chemical hallmarks of the TME, and discuss how these tumor characteristics either currently are, or may ultimately be targeted to improve cancer therapies.

@article{RN172,
   author = {Murovec, T. and Sweeney, D. C. and Latouche, E. and Davalos, R. V. and Brosseau, C.},
   title = {Modeling of Transmembrane Potential in Realistic Multicellular Structures before Electroporation},
   journal = {Biophys J},
   volume = {111},
   number = {10},
   pages = {2286-2295},
   note = {1542-0086
Murovec, Tomo
Sweeney, Daniel C
Latouche, Eduardo
Davalos, Rafael V
Brosseau, Christian
R21 CA173092/CA/NCI NIH HHS/United States
Journal Article
United States
2016/11/17
Biophys J. 2016 Nov 15;111(10):2286-2295. doi: 10.1016/j.bpj.2016.10.005.},
   abstract = {Many approaches for studying the transmembrane potential (TMP) induced during the treatment of biological cells with pulsed electric fields have been reported. From the simple analytical models to more complex numerical models requiring significant computational resources, a gamut of methods have been used to recapitulate multicellular environments in silico. Cells have been modeled as simple shapes in two dimensions as well as more complex geometries attempting to replicate realistic cell shapes. In this study, we describe a method for extracting realistic cell morphologies from fluorescence microscopy images to generate the piecewise continuous mesh used to develop a finite element model in two dimensions. The preelectroporation TMP induced in tightly packed cells is analyzed for two sets of pulse parameters inspired by clinical irreversible electroporation treatments. We show that high-frequency bipolar pulse trains are better, and more homogeneously raise the TMP of tightly packed cells to a simulated electroporation threshold than conventional irreversible electroporation pulse trains, at the expense of larger applied potentials. Our results demonstrate the viability of our method and emphasize the importance of considering multicellular effects in the numerical models used for studying the response of biological tissues exposed to electric fields.},
   keywords = {Animals
*Electroporation
Finite Element Analysis
*Membrane Potentials
Mice
Microscopy, Fluorescence
*Models, Biological},
   ISSN = {0006-3495 (Print)
0006-3495},
   DOI = {10.1016/j.bpj.2016.10.005},
   year = {2016},
   type = {Journal Article}
}

Many approaches for studying the transmembrane potential (TMP) induced during the treatment of biological cells with pulsed electric fields have been reported. From the simple analytical models to more complex numerical models requiring significant computational resources, a gamut of methods have been used to recapitulate multicellular environments in silico. Cells have been modeled as simple shapes in two dimensions as well as more complex geometries attempting to replicate realistic cell shapes. In this study, we describe a method for extracting realistic cell morphologies from fluorescence microscopy images to generate the piecewise continuous mesh used to develop a finite element model in two dimensions. The preelectroporation TMP induced in tightly packed cells is analyzed for two sets of pulse parameters inspired by clinical irreversible electroporation treatments. We show that high-frequency bipolar pulse trains are better, and more homogeneously raise the TMP of tightly packed cells to a simulated electroporation threshold than conventional irreversible electroporation pulse trains, at the expense of larger applied potentials. Our results demonstrate the viability of our method and emphasize the importance of considering multicellular effects in the numerical models used for studying the response of biological tissues exposed to electric fields.

@article{RN175,
   author = {Siddiqui, I. A. and Latouche, E. L. and DeWitt, M. R. and Swet, J. H. and Kirks, R. C. and Baker, E. H. and Iannitti, D. A. and Vrochides, D. and Davalos, R. V. and McKillop, I. H.},
   title = {Induction of rapid, reproducible hepatic ablations using next-generation, high frequency irreversible electroporation (H-FIRE) in vivo},
   journal = {HPB (Oxford)},
   volume = {18},
   number = {9},
   pages = {726-34},
   note = {1477-2574
Siddiqui, Imran A
Latouche, Eduardo L
DeWitt, Matthew R
Swet, Jacob H
Kirks, Russell C
Baker, Erin H
Iannitti, David A
Vrochides, Dionisios
Davalos, Rafael V
McKillop, Iain H
Journal Article
Research Support, Non-U.S. Gov't
England
2016/09/07
HPB (Oxford). 2016 Sep;18(9):726-34. doi: 10.1016/j.hpb.2016.06.015. Epub 2016 Jul 26.},
   abstract = {INTRODUCTION: Irreversible electroporation (IRE) offers an alternative to thermal tissue ablation in situ. High-frequency IRE (H-FIRE), employing ultra-short bipolar electrical pulses, may overcome limitations associated with existing IRE technology to create rapid, reproducible liver ablations in vivo. METHODS: IRE electrodes (1.5 cm spacing) were inserted into the hepatic parenchyma of swine (n = 3) under surgical anesthesia. In the absence of paralytics or cardiac synchronization five independent H-FIRE ablations were performed per liver using 100, 200, or 300 pulses (2250 V, 2-5-2 μs configuration). Animals were maintained under isoflurane anesthesia for 6 h prior to analysis of ablation size, reproducibility, and apoptotic cell death. RESULTS: Mean ablation time was 230 ± 31 s and no EKG abnormalities occurred during H-FIRE. In 1/15 HFIRE's minor muscle twitch (rectus abdominis) was recorded. Necropsy revealed reproducible ablation areas (34 ± 4 mm(2), 88 ± 11 mm(2) and 110 ± 11 mm(2); 100-, 200- and 300-pulses respectively). Tissue damage was predominantly apoptotic at pulse delivery ≤200 pulses, after which increasing evidence of tissue necrosis was observed. CONCLUSION: H-FIRE can be used to induce rapid, predictable ablations in hepatic tissue without the need for intraoperative paralytics or cardiac synchronization. These advantages may overcome limitations that restrict currently available IRE technology for hepatic ablations.},
   keywords = {Animals
Apoptosis
*Electroporation
Female
Hepatectomy/adverse effects/*methods
Liver/pathology/*surgery
Models, Animal
Reproducibility of Results
Sus scrofa
Time Factors},
   ISSN = {1365-182X (Print)
1365-182x},
   DOI = {10.1016/j.hpb.2016.06.015},
   year = {2016},
   type = {Journal Article}
}

INTRODUCTION: Irreversible electroporation (IRE) offers an alternative to thermal tissue ablation in situ. High-frequency IRE (H-FIRE), employing ultra-short bipolar electrical pulses, may overcome limitations associated with existing IRE technology to create rapid, reproducible liver ablations in vivo. METHODS: IRE electrodes (1.5 cm spacing) were inserted into the hepatic parenchyma of swine (n = 3) under surgical anesthesia. In the absence of paralytics or cardiac synchronization five independent H-FIRE ablations were performed per liver using 100, 200, or 300 pulses (2250 V, 2-5-2 μs configuration). Animals were maintained under isoflurane anesthesia for 6 h prior to analysis of ablation size, reproducibility, and apoptotic cell death. RESULTS: Mean ablation time was 230 ± 31 s and no EKG abnormalities occurred during H-FIRE. In 1/15 HFIRE's minor muscle twitch (rectus abdominis) was recorded. Necropsy revealed reproducible ablation areas (34 ± 4 mm(2), 88 ± 11 mm(2) and 110 ± 11 mm(2); 100-, 200- and 300-pulses respectively). Tissue damage was predominantly apoptotic at pulse delivery ≤200 pulses, after which increasing evidence of tissue necrosis was observed. CONCLUSION: H-FIRE can be used to induce rapid, predictable ablations in hepatic tissue without the need for intraoperative paralytics or cardiac synchronization. These advantages may overcome limitations that restrict currently available IRE technology for hepatic ablations.

@article{RN176,
   author = {Sweeney, D. C. and Reberšek, M. and Dermol, J. and Rems, L. and Miklavčič, D. and Davalos, R. V.},
   title = {Quantification of cell membrane permeability induced by monopolar and high-frequency bipolar bursts of electrical pulses},
   journal = {Biochim Biophys Acta},
   volume = {1858},
   number = {11},
   pages = {2689-2698},
   note = {Sweeney, Daniel C
Reberšek, Matej
Dermol, Janja
Rems, Lea
Miklavčič, Damijan
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Netherlands
2016/07/04
Biochim Biophys Acta. 2016 Nov;1858(11):2689-2698. doi: 10.1016/j.bbamem.2016.06.024. Epub 2016 Jun 29.},
   abstract = {High-frequency bipolar electric pulses have been shown to mitigate undesirable muscle contraction during irreversible electroporation (IRE) therapy. Here, we evaluate the potential applicability of such pulses for introducing exogenous molecules into cells, such as in electrochemotherapy (ECT). For this purpose we develop a method for calculating the time course of the effective permeability of an electroporated cell membrane based on real-time imaging of propidium transport into single cells that allows a quantitative comparison between different pulsing schemes. We calculate the effective permeability for several pulsed electric field treatments including trains of 100μs monopolar pulses, conventionally used in IRE and ECT, and pulse trains containing bursts or evenly-spaced 1μs bipolar pulses. We show that shorter bipolar pulses induce lower effective membrane permeability than longer monopolar pulses with equivalent treatment times. This lower efficiency can be attributed to incomplete membrane charging. Nevertheless, bipolar pulses could be used for increasing the uptake of small molecules into cells more symmetrically, but at the expense of higher applied voltages. These data indicate that high-frequency bipolar bursts of electrical pulses may be designed to electroporate cells as effectively as and more homogeneously than conventional monopolar pulses.},
   keywords = {Animals
Biological Transport
CHO Cells
Cell Membrane/*metabolism
Cell Membrane Permeability
Cricetulus
Electrodes
Electroporation/*methods
Membrane Potentials/physiology
Propidium/*metabolism
Single-Cell Analysis/instrumentation/*methods
Bipolar electrical pulses
Electrochemotherapy
Electroporation
Gene electrotransfer
Irreversible electroporation
Permeability},
   ISSN = {0006-3002 (Print)
0006-3002},
   DOI = {10.1016/j.bbamem.2016.06.024},
   year = {2016},
   type = {Journal Article}
}

High-frequency bipolar electric pulses have been shown to mitigate undesirable muscle contraction during irreversible electroporation (IRE) therapy. Here, we evaluate the potential applicability of such pulses for introducing exogenous molecules into cells, such as in electrochemotherapy (ECT). For this purpose we develop a method for calculating the time course of the effective permeability of an electroporated cell membrane based on real-time imaging of propidium transport into single cells that allows a quantitative comparison between different pulsing schemes. We calculate the effective permeability for several pulsed electric field treatments including trains of 100μs monopolar pulses, conventionally used in IRE and ECT, and pulse trains containing bursts or evenly-spaced 1μs bipolar pulses. We show that shorter bipolar pulses induce lower effective membrane permeability than longer monopolar pulses with equivalent treatment times. This lower efficiency can be attributed to incomplete membrane charging. Nevertheless, bipolar pulses could be used for increasing the uptake of small molecules into cells more symmetrically, but at the expense of higher applied voltages. These data indicate that high-frequency bipolar bursts of electrical pulses may be designed to electroporate cells as effectively as and more homogeneously than conventional monopolar pulses.

@article{RN188,
   author = {Baah-Dwomoh, A. and Rolong, A. and Gatenholm, P. and Davalos, R. V.},
   title = {The feasibility of using irreversible electroporation to introduce pores in bacterial cellulose scaffolds for tissue engineering},
   journal = {Appl Microbiol Biotechnol},
   volume = {99},
   number = {11},
   pages = {4785-94},
   note = {1432-0614
Baah-Dwomoh, Adwoa
Rolong, Andrea
Gatenholm, Paul
Davalos, Rafael V
R43 AG044153/AG/NIA NIH HHS/United States
R43 AG044153-01A1/AG/NIA NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
Germany
2015/02/19
Appl Microbiol Biotechnol. 2015 Jun;99(11):4785-94. doi: 10.1007/s00253-015-6445-0. Epub 2015 Feb 18.},
   abstract = {This work investigates the feasibility of the use of irreversible electroporation (IRE) in the biofabrication of 3D cellulose nanofibril networks via the bacterial strain Gluconacetobacter xylinus. IRE uses electrical pulses to increase membrane permeability by altering the transmembrane potential; past a threshold, damage to the cell becomes too great and leads to cell death. We hypothesized that using IRE to kill the bacteria at specific locations and particular times, we could introduce conduits in the overall scaffold by preventing cellulose biosynthesis locally. Through mathematical modeling and experimental techniques, electrical effects were investigated and the parameters for IRE of G. xylinus were determined. We found that for a specific set of parameters, an applied electric field of 8 to 12.5 kV/cm, producing a local field of 3 kV/cm, was sufficient to kill most of the bacteria and create a localized pore. However, an applied electric field of 17.5 kV/cm was required to kill all. Results suggest that IRE may be an effective tool to create scaffolds with appropriate porosity for orthopedic applications. Ideally, these engineered scaffolds could be used to successfully treat osteochondral defects.},
   keywords = {Cellulose/*chemistry/*metabolism
*Electroporation
Gluconacetobacter/*metabolism
Microbial Viability
Nanofibers/*chemistry
Tissue Engineering/*methods
*Tissue Scaffolds},
   ISSN = {0175-7598 (Print)
0175-7598},
   DOI = {10.1007/s00253-015-6445-0},
   year = {2015},
   type = {Journal Article}
}

This work investigates the feasibility of the use of irreversible electroporation (IRE) in the biofabrication of 3D cellulose nanofibril networks via the bacterial strain Gluconacetobacter xylinus. IRE uses electrical pulses to increase membrane permeability by altering the transmembrane potential; past a threshold, damage to the cell becomes too great and leads to cell death. We hypothesized that using IRE to kill the bacteria at specific locations and particular times, we could introduce conduits in the overall scaffold by preventing cellulose biosynthesis locally. Through mathematical modeling and experimental techniques, electrical effects were investigated and the parameters for IRE of G. xylinus were determined. We found that for a specific set of parameters, an applied electric field of 8 to 12.5 kV/cm, producing a local field of 3 kV/cm, was sufficient to kill most of the bacteria and create a localized pore. However, an applied electric field of 17.5 kV/cm was required to kill all. Results suggest that IRE may be an effective tool to create scaffolds with appropriate porosity for orthopedic applications. Ideally, these engineered scaffolds could be used to successfully treat osteochondral defects.

@article{RN183,
   author = {Bhonsle, S. P. and Arena, C. B. and Sweeney, D. C. and Davalos, R. V.},
   title = {Mitigation of impedance changes due to electroporation therapy using bursts of high-frequency bipolar pulses},
   journal = {Biomed Eng Online},
   volume = {14 Suppl 3},
   number = {Suppl 3},
   pages = {S3},
   note = {1475-925x
Bhonsle, Suyashree P
Arena, Christopher B
Sweeney, Daniel C
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2015/09/12
Biomed Eng Online. 2015;14 Suppl 3(Suppl 3):S3. doi: 10.1186/1475-925X-14-S3-S3. Epub 2015 Aug 27.},
   abstract = {BACKGROUND: For electroporation-based therapies, accurate modeling of the electric field distribution within the target tissue is important for predicting the treatment volume. In response to conventional, unipolar pulses, the electrical impedance of a tissue varies as a function of the local electric field, leading to a redistribution of the field. These dynamic impedance changes, which depend on the tissue type and the applied electric field, need to be quantified a priori, making mathematical modeling complicated. Here, it is shown that the impedance changes during high-frequency, bipolar electroporation therapy are reduced, and the electric field distribution can be approximated using the analytical solution to Laplace's equation that is valid for a homogeneous medium of constant conductivity. METHODS: Two methods were used to examine the agreement between the analytical solution to Laplace's equation and the electric fields generated by 100 µs unipolar pulses and bursts of 1 µs bipolar pulses. First, pulses were applied to potato tuber tissue while an infrared camera was used to monitor the temperature distribution in real-time as a corollary to the electric field distribution. The analytical solution was overlaid on the thermal images for a qualitative assessment of the electric fields. Second, potato ablations were performed and the lesion size was measured along the x- and y-axes. These values were compared to the analytical solution to quantify its ability to predict treatment outcomes. To analyze the dynamic impedance changes due to electroporation at different frequencies, electrical impedance measurements (1 Hz to 1 MHz) were made before and after the treatment of potato tissue. RESULTS: For high-frequency bipolar burst treatment, the thermal images closely mirrored the constant electric field contours. The potato tissue lesions differed from the analytical solution by 39.7 ± 1.3 % (x-axis) and 6.87 ± 6.26 % (y-axis) for conventional unipolar pulses, and 15.46 ± 1.37 % (x-axis) and 3.63 ± 5.9 % (y-axis) for high- frequency bipolar pulses. CONCLUSIONS: The electric field distributions due to high-frequency, bipolar electroporation pulses can be closely approximated with the homogeneous analytical solution. This paves way for modeling fields without prior characterization of non-linear tissue properties, and thereby simplifying electroporation procedures.},
   keywords = {*Electric Conductivity
Electric Impedance
Electrochemotherapy/*methods
Models, Theoretical
Solanum tuberosum/cytology
Temperature},
   ISSN = {1475-925x},
   DOI = {10.1186/1475-925x-14-s3-s3},
   year = {2015},
   type = {Journal Article}
}

BACKGROUND: For electroporation-based therapies, accurate modeling of the electric field distribution within the target tissue is important for predicting the treatment volume. In response to conventional, unipolar pulses, the electrical impedance of a tissue varies as a function of the local electric field, leading to a redistribution of the field. These dynamic impedance changes, which depend on the tissue type and the applied electric field, need to be quantified a priori, making mathematical modeling complicated. Here, it is shown that the impedance changes during high-frequency, bipolar electroporation therapy are reduced, and the electric field distribution can be approximated using the analytical solution to Laplace's equation that is valid for a homogeneous medium of constant conductivity. METHODS: Two methods were used to examine the agreement between the analytical solution to Laplace's equation and the electric fields generated by 100 µs unipolar pulses and bursts of 1 µs bipolar pulses. First, pulses were applied to potato tuber tissue while an infrared camera was used to monitor the temperature distribution in real-time as a corollary to the electric field distribution. The analytical solution was overlaid on the thermal images for a qualitative assessment of the electric fields. Second, potato ablations were performed and the lesion size was measured along the x- and y-axes. These values were compared to the analytical solution to quantify its ability to predict treatment outcomes. To analyze the dynamic impedance changes due to electroporation at different frequencies, electrical impedance measurements (1 Hz to 1 MHz) were made before and after the treatment of potato tissue. RESULTS: For high-frequency bipolar burst treatment, the thermal images closely mirrored the constant electric field contours. The potato tissue lesions differed from the analytical solution by 39.7 ± 1.3 % (x-axis) and 6.87 ± 6.26 % (y-axis) for conventional unipolar pulses, and 15.46 ± 1.37 % (x-axis) and 3.63 ± 5.9 % (y-axis) for high- frequency bipolar pulses. CONCLUSIONS: The electric field distributions due to high-frequency, bipolar electroporation pulses can be closely approximated with the homogeneous analytical solution. This paves way for modeling fields without prior characterization of non-linear tissue properties, and thereby simplifying electroporation procedures.

@article{RN186,
   author = {Bonakdar, M. and Latouche, E. L. and Mahajan, R. L. and Davalos, R. V.},
   title = {The Feasibility of a Smart Surgical Probe for Verification of IRE Treatments Using Electrical Impedance Spectroscopy},
   journal = {IEEE Trans Biomed Eng},
   volume = {62},
   number = {11},
   pages = {2674-84},
   note = {1558-2531
Bonakdar, Mohammad
Latouche, Eduardo L
Mahajan, Roop L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2015/06/10
IEEE Trans Biomed Eng. 2015 Nov;62(11):2674-84. doi: 10.1109/TBME.2015.2441636. Epub 2015 Jun 4.},
   abstract = {SIGNIFICANCE: Irreversible electroporation (IRE) is gaining popularity as a focal ablation modality for the treatment of unresectable tumors. One clinical limitation of IRE is the absence of methods for real-time treatment evaluation, namely actively monitoring the dimensions of the induced lesion. This information is critical to ensure a complete treatment and minimize collateral damage to the surrounding healthy tissue. GOAL: In this study, we are taking advantage of the biophysical properties of living tissues to address this critical demand. METHODS: Using advanced microfabrication techniques, we have developed an electrical impedance microsensor to collect impedance data along the length of a bipolar IRE probe for treatment verification. For probe characterization and interpretation of the readings, we used potato tuber, which is a suitable platform for IRE experiments without having the complexities of in vivo or ex vivo models. We used the impedance spectra, along with an electrical model of the tissue, to obtain critical parameters such as the conductivity of the tissue before, during, and after completion of treatment. To validate our results, we used a finite element model to simulate the electric field distribution during treatments in each potato. RESULTS: It is shown that electrical impedance spectroscopy could be used as a technique for treatment verification, and when combined with appropriate FEM modeling can determine the lesion dimensions. CONCLUSIONS: This technique has the potential to be readily translated for use with other ablation modalities already being used in clinical settings for the treatment of malignancies.},
   keywords = {Ablation Techniques/*instrumentation/methods
Dielectric Spectroscopy/*instrumentation/methods
Electrochemotherapy/*instrumentation/methods
Electrodes
Equipment Design
Feasibility Studies
Finite Element Analysis
Models, Biological},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2015.2441636},
   year = {2015},
   type = {Journal Article}
}

SIGNIFICANCE: Irreversible electroporation (IRE) is gaining popularity as a focal ablation modality for the treatment of unresectable tumors. One clinical limitation of IRE is the absence of methods for real-time treatment evaluation, namely actively monitoring the dimensions of the induced lesion. This information is critical to ensure a complete treatment and minimize collateral damage to the surrounding healthy tissue. GOAL: In this study, we are taking advantage of the biophysical properties of living tissues to address this critical demand. METHODS: Using advanced microfabrication techniques, we have developed an electrical impedance microsensor to collect impedance data along the length of a bipolar IRE probe for treatment verification. For probe characterization and interpretation of the readings, we used potato tuber, which is a suitable platform for IRE experiments without having the complexities of in vivo or ex vivo models. We used the impedance spectra, along with an electrical model of the tissue, to obtain critical parameters such as the conductivity of the tissue before, during, and after completion of treatment. To validate our results, we used a finite element model to simulate the electric field distribution during treatments in each potato. RESULTS: It is shown that electrical impedance spectroscopy could be used as a technique for treatment verification, and when combined with appropriate FEM modeling can determine the lesion dimensions. CONCLUSIONS: This technique has the potential to be readily translated for use with other ablation modalities already being used in clinical settings for the treatment of malignancies.

@article{RN194,
   author = {Colacino, K. R. and Arena, C. B. and Dong, S. and Roman, M. and Davalos, R. V. and Lee, Y. W.},
   title = {Folate Conjugated Cellulose Nanocrystals Potentiate Irreversible Electroporation-induced Cytotoxicity for the Selective Treatment of Cancer Cells},
   journal = {Technol Cancer Res Treat},
   volume = {14},
   number = {6},
   pages = {757-66},
   note = {1533-0338
Colacino, Katelyn R
Arena, Christopher B
Dong, Shuping
Roman, Maren
Davalos, Rafael V
Lee, Yong W
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2014/04/23
Technol Cancer Res Treat. 2015 Dec;14(6):757-66. doi: 10.7785/tcrt.2012.500428. Epub 2014 Nov 26.},
   abstract = {Cellulose nanocrystals are rod-shaped, crystalline nanoparticles that have shown prom-ise in a number of industrial applications for their unique chemical and physical properties. However, investigations of their abilities in the biomedical field are limited. The goal of this study is to show the potential use of folic acid-conjugated cellulose nanocrystals in the potentiation of irreversible electroporation-induced cell death in folate receptor (FR)-positive cancers. We optimized key pulse parameters including pulse duration, intensity, and incubation time with nanoparticles prior to electroporation. FR-positive cancer cells, KB and MDA-MB-468, were preincubated with cellulose nanocrystals (CNCs) conjugated with the targeting molecule folic acid (FA), 10 and 20 min respectively, prior to application of the optimized pulse electric field (PEF), 600 and 500 V/cm respectively. We have shown cellulose nanocrystals' ability to potentiate a new technique for tumor ablation, irreversible electroporation. Pre-incubation with FA-conjugated CNCs (CNC-FA) has shown a significant increase in cytotoxicity induced by irreversible electroporation in FR-positive cancer cells, KB and MDA-MB-468. Non-targeted CNCs (CNC-COOH) did not potentiate IRE when preincubated at the same parameters as previously stated in these cell types. In addition, CNC-FA did not potentiate irreversible electroporation-induced cytotoxicity in a FR-negative cancer cell type, A549. Without changing irreversible electroporation parameters it is possible to increase the cytotoxic effect on FR-positive cancer cells by exploiting the specific binding of FA to the FR, while not causing further damage to FR-negative tissue.},
   keywords = {Cell Line, Tumor
Cellulose
Drug Delivery Systems/*methods
Electrochemotherapy/*methods
Finite Element Analysis
Folic Acid/*administration & dosage
Humans
Microscopy, Confocal
*Nanoparticles
Cancer treatment
Folate receptor
Targeted drug delivery},
   ISSN = {1533-0338},
   DOI = {10.7785/tcrt.2012.500428},
   year = {2015},
   type = {Journal Article}
}

Cellulose nanocrystals are rod-shaped, crystalline nanoparticles that have shown prom-ise in a number of industrial applications for their unique chemical and physical properties. However, investigations of their abilities in the biomedical field are limited. The goal of this study is to show the potential use of folic acid-conjugated cellulose nanocrystals in the potentiation of irreversible electroporation-induced cell death in folate receptor (FR)-positive cancers. We optimized key pulse parameters including pulse duration, intensity, and incubation time with nanoparticles prior to electroporation. FR-positive cancer cells, KB and MDA-MB-468, were preincubated with cellulose nanocrystals (CNCs) conjugated with the targeting molecule folic acid (FA), 10 and 20 min respectively, prior to application of the optimized pulse electric field (PEF), 600 and 500 V/cm respectively. We have shown cellulose nanocrystals' ability to potentiate a new technique for tumor ablation, irreversible electroporation. Pre-incubation with FA-conjugated CNCs (CNC-FA) has shown a significant increase in cytotoxicity induced by irreversible electroporation in FR-positive cancer cells, KB and MDA-MB-468. Non-targeted CNCs (CNC-COOH) did not potentiate IRE when preincubated at the same parameters as previously stated in these cell types. In addition, CNC-FA did not potentiate irreversible electroporation-induced cytotoxicity in a FR-negative cancer cell type, A549. Without changing irreversible electroporation parameters it is possible to increase the cytotoxic effect on FR-positive cancer cells by exploiting the specific binding of FA to the FR, while not causing further damage to FR-negative tissue.

@article{RN187,
   author = {Davalos, R. V. and Bhonsle, S. and Neal, R. E., 2nd},
   title = {Implications and considerations of thermal effects when applying irreversible electroporation tissue ablation therapy},
   journal = {Prostate},
   volume = {75},
   number = {10},
   pages = {1114-8},
   note = {1097-0045
Davalos, Rafael V
Bhonsle, Suyashree
Neal, Robert E 2nd
Comment
Letter
United States
2015/03/27
Prostate. 2015 Jul 1;75(10):1114-8. doi: 10.1002/pros.22986. Epub 2015 Mar 23.},
   abstract = {Irreversible electroporation (IRE) describes a cellular response to electric field exposure, resulting in the formation of nanoscale defects that can lead to cell death. While this behavior occurs independently of thermally-induced processes, therapeutic ablation of targeted tissues with IRE uses a series of brief electric pulses, whose parameters result in secondary Joule heating of the tissue. Where contemporary clinical pulse protocols use aggressive energy regimes, additional evidence is supplementing original studies that assert care must be taken in clinical ablation protocols to ensure the cumulative thermal effects do not induce damage that will alter outcomes for therapies using the IRE non-thermal cell death process for tissue ablation. In this letter, we seek to clarify the nomenclature regarding IRE as a non-thermal ablation technique, as well as identify existing literature that uses experimental, clinical, and numerical results to discretely address and evaluate the thermal considerations relevant when applying IRE in clinical scenarios, including several approaches for reducing these effects. Existing evidence in the literature describes cell response to electric fields, suggesting cell death from IRE is a unique process, independent from traditional thermal damage. Numerical simulations, as well as preclinical and clinical findings demonstrate the ability to deliver therapeutic IRE ablation without occurrence of morbidity associated with thermal therapies. Clinical IRE therapy generates thermal effects, which may moderate the non-thermal aspects of IRE ablation. Appropriate protocol development, utilization, and pulse delivery devices may be implemented to restrain these effects and maintain IRE as the vastly predominant tissue death modality, reducing therapy-mitigating thermal damage. Clinical applications of IRE should consider thermal effects and employ protocols to ensure safe and effective therapy delivery.},
   keywords = {Electroporation/*methods
*Hot Temperature
Humans
Male
Prostatic Neoplasms/*therapy
Ire
focal targeted treatments
minimally invasive surgery
non-thermal ablation},
   ISSN = {0270-4137 (Print)
0270-4137},
   DOI = {10.1002/pros.22986},
   year = {2015},
   type = {Journal Article}
}

Irreversible electroporation (IRE) describes a cellular response to electric field exposure, resulting in the formation of nanoscale defects that can lead to cell death. While this behavior occurs independently of thermally-induced processes, therapeutic ablation of targeted tissues with IRE uses a series of brief electric pulses, whose parameters result in secondary Joule heating of the tissue. Where contemporary clinical pulse protocols use aggressive energy regimes, additional evidence is supplementing original studies that assert care must be taken in clinical ablation protocols to ensure the cumulative thermal effects do not induce damage that will alter outcomes for therapies using the IRE non-thermal cell death process for tissue ablation. In this letter, we seek to clarify the nomenclature regarding IRE as a non-thermal ablation technique, as well as identify existing literature that uses experimental, clinical, and numerical results to discretely address and evaluate the thermal considerations relevant when applying IRE in clinical scenarios, including several approaches for reducing these effects. Existing evidence in the literature describes cell response to electric fields, suggesting cell death from IRE is a unique process, independent from traditional thermal damage. Numerical simulations, as well as preclinical and clinical findings demonstrate the ability to deliver therapeutic IRE ablation without occurrence of morbidity associated with thermal therapies. Clinical IRE therapy generates thermal effects, which may moderate the non-thermal aspects of IRE ablation. Appropriate protocol development, utilization, and pulse delivery devices may be implemented to restrain these effects and maintain IRE as the vastly predominant tissue death modality, reducing therapy-mitigating thermal damage. Clinical applications of IRE should consider thermal effects and employ protocols to ensure safe and effective therapy delivery.

@article{RN181,
   author = {Ivey, J. W. and Latouche, E. L. and Sano, M. B. and Rossmeisl, J. H. and Davalos, R. V. and Verbridge, S. S.},
   title = {Targeted cellular ablation based on the morphology of malignant cells},
   journal = {Sci Rep},
   volume = {5},
   pages = {17157},
   note = {2045-2322
Ivey, Jill W
Latouche, Eduardo L
Sano, Michael B
Rossmeisl, John H
Davalos, Rafael V
Verbridge, Scott S
R21 CA192042/CA/NCI NIH HHS/United States
R21CA192042/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2015/11/26
Sci Rep. 2015 Nov 24;5:17157. doi: 10.1038/srep17157.},
   abstract = {Treatment of glioblastoma multiforme (GBM) is especially challenging due to a shortage of methods to preferentially target diffuse infiltrative cells, and therapy-resistant glioma stem cell populations. Here we report a physical treatment method based on electrical disruption of cells, whose action depends strongly on cellular morphology. Interestingly, numerical modeling suggests that while outer lipid bilayer disruption induced by long pulses (~100 μs) is enhanced for larger cells, short pulses (~1 μs) preferentially result in high fields within the cell interior, which scale in magnitude with nucleus size. Because enlarged nuclei represent a reliable indicator of malignancy, this suggested a means of preferentially targeting malignant cells. While we demonstrate killing of both normal and malignant cells using pulsed electric fields (PEFs) to treat spontaneous canine GBM, we proposed that properly tuned PEFs might provide targeted ablation based on nuclear size. Using 3D hydrogel models of normal and malignant brain tissues, which permit high-resolution interrogation during treatment testing, we confirmed that PEFs could be tuned to preferentially kill cancerous cells. Finally, we estimated the nuclear envelope electric potential disruption needed for cell death from PEFs. Our results may be useful in safely targeting the therapy-resistant cell niches that cause recurrence of GBM tumors.},
   keywords = {Animals
Brain Neoplasms/pathology/therapy/*veterinary
Cell Line, Tumor
Cell Nucleus Size
Cell Shape
Cell Survival
Coculture Techniques
Dog Diseases/pathology/*therapy
Dogs
Electroporation
Finite Element Analysis
Glioblastoma/pathology/therapy/*veterinary
Humans
Hydrogels/chemistry
Single-Cell Analysis},
   ISSN = {2045-2322},
   DOI = {10.1038/srep17157},
   year = {2015},
   type = {Journal Article}
}

Treatment of glioblastoma multiforme (GBM) is especially challenging due to a shortage of methods to preferentially target diffuse infiltrative cells, and therapy-resistant glioma stem cell populations. Here we report a physical treatment method based on electrical disruption of cells, whose action depends strongly on cellular morphology. Interestingly, numerical modeling suggests that while outer lipid bilayer disruption induced by long pulses ( 100 μs) is enhanced for larger cells, short pulses ( 1 μs) preferentially result in high fields within the cell interior, which scale in magnitude with nucleus size. Because enlarged nuclei represent a reliable indicator of malignancy, this suggested a means of preferentially targeting malignant cells. While we demonstrate killing of both normal and malignant cells using pulsed electric fields (PEFs) to treat spontaneous canine GBM, we proposed that properly tuned PEFs might provide targeted ablation based on nuclear size. Using 3D hydrogel models of normal and malignant brain tissues, which permit high-resolution interrogation during treatment testing, we confirmed that PEFs could be tuned to preferentially kill cancerous cells. Finally, we estimated the nuclear envelope electric potential disruption needed for cell death from PEFs. Our results may be useful in safely targeting the therapy-resistant cell niches that cause recurrence of GBM tumors.

@article{RN189,
   author = {Jiang, C. and Davalos, R. V. and Bischof, J. C.},
   title = {A review of basic to clinical studies of irreversible electroporation therapy},
   journal = {IEEE Trans Biomed Eng},
   volume = {62},
   number = {1},
   pages = {4-20},
   note = {1558-2531
Jiang, Chunlan
Davalos, Rafael V
Bischof, John C
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Review
United States
2014/11/13
IEEE Trans Biomed Eng. 2015 Jan;62(1):4-20. doi: 10.1109/TBME.2014.2367543.},
   abstract = {The use of irreversible electroporation (IRE) for cancer treatment has increased sharply over the past decade. As a nonthermal therapy, IRE offers several potential benefits over other focal therapies, which include 1) short treatment delivery time, 2) reduced collateral thermal injury, and 3) the ability to treat tumors adjacent to major blood vessels. These advantages have stimulated widespread interest in basic through clinical studies of IRE. For instance, many in vitro and in vivo studies now identify treatment planning protocols (IRE threshold, pulse parameters, etc.), electrode delivery (electrode design, placement, intraoperative imaging methods, etc.), injury evaluation (methods and timing), and treatment efficacy in different cancer models. Therefore, this study reviews the in vitro, translational, and clinical studies of IRE cancer therapy based on major experimental studies particularly within the past decade. Further, this study provides organized data and facts to assist further research, optimization, and clinical applications of IRE.},
   keywords = {Animals
Cell Membrane Permeability/*radiation effects
Electric Stimulation Therapy/methods
Electrochemotherapy/*methods
Electromagnetic Fields
Evidence-Based Medicine
Humans
Models, Biological
Neoplasms/pathology/*physiopathology/*therapy
Neovascularization, Pathologic/*pathology/physiopathology/*therapy
Treatment Outcome},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2014.2367543},
   year = {2015},
   type = {Journal Article}
}

The use of irreversible electroporation (IRE) for cancer treatment has increased sharply over the past decade. As a nonthermal therapy, IRE offers several potential benefits over other focal therapies, which include 1) short treatment delivery time, 2) reduced collateral thermal injury, and 3) the ability to treat tumors adjacent to major blood vessels. These advantages have stimulated widespread interest in basic through clinical studies of IRE. For instance, many in vitro and in vivo studies now identify treatment planning protocols (IRE threshold, pulse parameters, etc.), electrode delivery (electrode design, placement, intraoperative imaging methods, etc.), injury evaluation (methods and timing), and treatment efficacy in different cancer models. Therefore, this study reviews the in vitro, translational, and clinical studies of IRE cancer therapy based on major experimental studies particularly within the past decade. Further, this study provides organized data and facts to assist further research, optimization, and clinical applications of IRE.

@article{RN184,
   author = {Miklavcic, D. and Davalos, R. V.},
   title = {Electrochemotherapy (ECT) and irreversible electroporation (IRE) -advanced techniques for treating deep-seated tumors based on electroporation},
   journal = {Biomed Eng Online},
   volume = {14 Suppl 3},
   number = {Suppl 3},
   pages = {I1},
   note = {1475-925x
Miklavcic, Damijan
Davalos, Rafael V
Editorial
England
2015/09/12
Biomed Eng Online. 2015;14 Suppl 3(Suppl 3):I1. doi: 10.1186/1475-925X-14-S3-I1. Epub 2015 Aug 27.},
   keywords = {*Electrochemotherapy
Humans
Neoplasms/*drug therapy},
   ISSN = {1475-925x},
   DOI = {10.1186/1475-925x-14-s3-i1},
   year = {2015},
   type = {Journal Article}
}

@article{RN190,
   author = {Neal, R. E., 2nd and Garcia, P. A. and Kavnoudias, H. and Rosenfeldt, F. and McLean, C. A. and Earl, V. and Bergman, J. and Davalos, R. V. and Thomson, K. R.},
   title = {In vivo irreversible electroporation kidney ablation: experimentally correlated numerical models},
   journal = {IEEE Trans Biomed Eng},
   volume = {62},
   number = {2},
   pages = {561-9},
   note = {1558-2531
Neal, Robert E 2nd
Garcia, Paulo A
Kavnoudias, Helen
Rosenfeldt, Franklin
Mclean, Catriona A
Earl, Victoria
Bergman, Joanne
Davalos, Rafael V
Thomson, Kenneth R
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2014/09/30
IEEE Trans Biomed Eng. 2015 Feb;62(2):561-9. doi: 10.1109/TBME.2014.2360374. Epub 2014 Sep 25.},
   abstract = {Irreversible electroporation (IRE) ablation uses brief electric pulses to kill a volume of tissue without damaging the structures contraindicated for surgical resection or thermal ablation, including blood vessels and ureters. IRE offers a targeted nephron-sparing approach for treating kidney tumors, but the relevant organ-specific electrical properties and cellular susceptibility to IRE electric pulses remain to be characterized. Here, a pulse protocol of 100 electric pulses, each 100 μs long, is delivered at 1 pulse/s to canine kidneys at three different voltage-to-distance ratios while measuring intrapulse current, completed 6 h before humane euthanasia. Numerical models were correlated with lesions and electrical measurements to determine electrical conductivity behavior and lethal electric field threshold. Three methods for modeling tissue response to the pulses were investigated (static, linear dynamic, and asymmetrical sigmoid dynamic), where the asymmetrical sigmoid dynamic conductivity function most accurately and precisely matched lesion dimensions, with a lethal electric field threshold of 575 ± 67 V/cm for the protocols used. The linear dynamic model also attains accurate predictions with a simpler function. These findings can aid renal IRE treatment planning under varying electrode geometries and pulse strengths. Histology showed a wholly necrotic core lesion at the highest electric fields, surrounded by a transitional perimeter of differential tissue viability dependent on renal structure.},
   keywords = {Ablation Techniques/*methods
Animals
Computer Simulation
Dogs
Electroporation/*methods
Kidney/pathology/*surgery
Male
*Models, Biological
Nephrectomy/*methods
Surgery, Computer-Assisted/methods
Treatment Outcome},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2014.2360374},
   year = {2015},
   type = {Journal Article}
}

Irreversible electroporation (IRE) ablation uses brief electric pulses to kill a volume of tissue without damaging the structures contraindicated for surgical resection or thermal ablation, including blood vessels and ureters. IRE offers a targeted nephron-sparing approach for treating kidney tumors, but the relevant organ-specific electrical properties and cellular susceptibility to IRE electric pulses remain to be characterized. Here, a pulse protocol of 100 electric pulses, each 100 μs long, is delivered at 1 pulse/s to canine kidneys at three different voltage-to-distance ratios while measuring intrapulse current, completed 6 h before humane euthanasia. Numerical models were correlated with lesions and electrical measurements to determine electrical conductivity behavior and lethal electric field threshold. Three methods for modeling tissue response to the pulses were investigated (static, linear dynamic, and asymmetrical sigmoid dynamic), where the asymmetrical sigmoid dynamic conductivity function most accurately and precisely matched lesion dimensions, with a lethal electric field threshold of 575 ± 67 V/cm for the protocols used. The linear dynamic model also attains accurate predictions with a simpler function. These findings can aid renal IRE treatment planning under varying electrode geometries and pulse strengths. Histology showed a wholly necrotic core lesion at the highest electric fields, surrounded by a transitional perimeter of differential tissue viability dependent on renal structure.

@article{RN185,
   author = {Rossmeisl, J. H., Jr. and Garcia, P. A. and Pancotto, T. E. and Robertson, J. L. and Henao-Guerrero, N. and Neal, R. E., 2nd and Ellis, T. L. and Davalos, R. V.},
   title = {Safety and feasibility of the NanoKnife system for irreversible electroporation ablative treatment of canine spontaneous intracranial gliomas},
   journal = {J Neurosurg},
   volume = {123},
   number = {4},
   pages = {1008-25},
   note = {1933-0693
Rossmeisl, John H Jr
Garcia, Paulo A
Pancotto, Theresa E
Robertson, John L
Henao-Guerrero, Natalia
Neal, Robert E 2nd
Ellis, Thomas L
Davalos, Rafael V
Clinical Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2015/07/04
J Neurosurg. 2015 Oct;123(4):1008-25. doi: 10.3171/2014.12.JNS141768. Epub 2015 Jul 3.},
   abstract = {OBJECT: Irreversible electroporation (IRE) is a novel nonthermal ablation technique that has been used for the treatment of solid cancers. However, it has not been evaluated for use in brain tumors. Here, the authors report on the safety and feasibility of using the NanoKnife IRE system for the treatment of spontaneous intracranial gliomas in dogs. METHODS: Client-owned dogs with a telencephalic glioma shown on MRI were eligible. Dog-specific treatment plans were generated by using MRI-based tissue segmentation, volumetric meshing, and finite element modeling. After biopsy confirmation of glioma, IRE treatment was delivered stereotactically with the NanoKnife system using pulse parameters and electrode configurations derived from therapeutic plans. The primary end point was an evaluation of safety over the 14 days immediately after treatment. Follow-up was continued for 12 months or until death with serial physical, neurological, laboratory, and MRI examinations. RESULTS: Seven dogs with glioma were treated. The mean age of the dogs was 9.3 ± 1.6 years, and the mean pretreatment tumor volume was 1.9 ± 1.4 cm(3). The median preoperative Karnofsky Performance Scale score was 70 (range 30-75). Severe posttreatment toxicity was observed in 2 of the 7 dogs; one developed fatal (Grade 5) aspiration pneumonia, and the other developed treatment-associated cerebral edema, which resulted in transient neurological deterioration. Results of posttreatment diagnostic imaging, tumor biopsies, and neurological examinations indicated that tumor ablation was achieved without significant direct neurotoxicity in 6 of the 7 dogs. The median 14-day post-IRE Karnofsky Performance Scale score of the 6 dogs that survived to discharge was 80 (range 60-90), and this score was improved over the pretreatment value in every case. Objective tumor responses were seen in 4 (80%) of 5 dogs with quantifiable target lesions. The median survival was 119 days (range 1 to > 940 days). CONCLUSION: With the incorporation of additional therapeutic planning procedures, the NanoKnife system is a novel technology capable of controlled IRE ablation of telencephalic gliomas.},
   keywords = {Animals
Brain Neoplasms/drug therapy/surgery/*veterinary
Combined Modality Therapy
Dog Diseases/*drug therapy/*surgery
Dogs
Electrochemotherapy/adverse effects/*methods
Feasibility Studies
Female
Glioma/drug therapy/surgery/*veterinary
Male
*Neurosurgical Procedures/instrumentation
Prospective Studies
*Telencephalon
CTCAE = Common Terminology Criteria for Adverse Events
DICOM = Digital Imaging and Communications in Medicine
GBM = glioblastoma multiforme
IRE = irreversible electroporation
IV = intravenous
KPS = Karnofsky Performance Scale
PBS = phosphate-buffered saline
PD = progressive disease
PDMS = polydimethylsiloxane
PGP = probe guide pedestal
RANO = response assessment in neurooncology
SD = stable disease
brain tumor
dog
electroporation
glioma
neurosurgery
oncology},
   ISSN = {0022-3085},
   DOI = {10.3171/2014.12.Jns141768},
   year = {2015},
   type = {Journal Article}
}

OBJECT: Irreversible electroporation (IRE) is a novel nonthermal ablation technique that has been used for the treatment of solid cancers. However, it has not been evaluated for use in brain tumors. Here, the authors report on the safety and feasibility of using the NanoKnife IRE system for the treatment of spontaneous intracranial gliomas in dogs. METHODS: Client-owned dogs with a telencephalic glioma shown on MRI were eligible. Dog-specific treatment plans were generated by using MRI-based tissue segmentation, volumetric meshing, and finite element modeling. After biopsy confirmation of glioma, IRE treatment was delivered stereotactically with the NanoKnife system using pulse parameters and electrode configurations derived from therapeutic plans. The primary end point was an evaluation of safety over the 14 days immediately after treatment. Follow-up was continued for 12 months or until death with serial physical, neurological, laboratory, and MRI examinations. RESULTS: Seven dogs with glioma were treated. The mean age of the dogs was 9.3 ± 1.6 years, and the mean pretreatment tumor volume was 1.9 ± 1.4 cm(3). The median preoperative Karnofsky Performance Scale score was 70 (range 30-75). Severe posttreatment toxicity was observed in 2 of the 7 dogs; one developed fatal (Grade 5) aspiration pneumonia, and the other developed treatment-associated cerebral edema, which resulted in transient neurological deterioration. Results of posttreatment diagnostic imaging, tumor biopsies, and neurological examinations indicated that tumor ablation was achieved without significant direct neurotoxicity in 6 of the 7 dogs. The median 14-day post-IRE Karnofsky Performance Scale score of the 6 dogs that survived to discharge was 80 (range 60-90), and this score was improved over the pretreatment value in every case. Objective tumor responses were seen in 4 (80%) of 5 dogs with quantifiable target lesions. The median survival was 119 days (range 1 to > 940 days). CONCLUSION: With the incorporation of additional therapeutic planning procedures, the NanoKnife system is a novel technology capable of controlled IRE ablation of telencephalic gliomas.

@article{RN182,
   author = {Sano, M. B. and Arena, C. B. and Bittleman, K. R. and DeWitt, M. R. and Cho, H. J. and Szot, C. S. and Saur, D. and Cissell, J. M. and Robertson, J. and Lee, Y. W. and Davalos, R. V.},
   title = {Bursts of Bipolar Microsecond Pulses Inhibit Tumor Growth},
   journal = {Sci Rep},
   volume = {5},
   pages = {14999},
   note = {2045-2322
Sano, Michael B
Arena, Christopher B
Bittleman, Katelyn R
DeWitt, Matthew R
Cho, Hyung J
Szot, Christopher S
Saur, Dieter
Cissell, James M
Robertson, John
Lee, Yong W
Davalos, Rafael V
K12 GM000678/GM/NIGMS NIH HHS/United States
Journal Article
Research Support, Non-U.S. Gov't
England
2015/10/16
Sci Rep. 2015 Oct 13;5:14999. doi: 10.1038/srep14999.},
   abstract = {Irreversible electroporation (IRE) is an emerging focal therapy which is demonstrating utility in the treatment of unresectable tumors where thermal ablation techniques are contraindicated. IRE uses ultra-short duration, high-intensity monopolar pulsed electric fields to permanently disrupt cell membranes within a well-defined volume. Though preliminary clinical results for IRE are promising, implementing IRE can be challenging due to the heterogeneous nature of tumor tissue and the unintended induction of muscle contractions. High-frequency IRE (H-FIRE), a new treatment modality which replaces the monopolar IRE pulses with a burst of bipolar pulses, has the potential to resolve these clinical challenges. We explored the pulse-duration space between 250 ns and 100 μs and determined the lethal electric field intensity for specific H-FIRE protocols using a 3D tumor mimic. Murine tumors were exposed to 120 bursts, each energized for 100 μs, containing individual pulses 1, 2, or 5 μs in duration. Tumor growth was significantly inhibited and all protocols were able to achieve complete regressions. The H-FIRE protocol substantially reduces muscle contractions and the therapy can be delivered without the need for a neuromuscular blockade. This work shows the potential for H-FIRE to be used as a focal therapy and merits its investigation in larger pre-clinical models.},
   keywords = {Animals
Cell Line, Tumor
Disease Models, Animal
Electroporation/*methods
Male
Mice
Neoplasms/*pathology/*therapy
Tumor Burden
Xenograft Model Antitumor Assays},
   ISSN = {2045-2322},
   DOI = {10.1038/srep14999},
   year = {2015},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is an emerging focal therapy which is demonstrating utility in the treatment of unresectable tumors where thermal ablation techniques are contraindicated. IRE uses ultra-short duration, high-intensity monopolar pulsed electric fields to permanently disrupt cell membranes within a well-defined volume. Though preliminary clinical results for IRE are promising, implementing IRE can be challenging due to the heterogeneous nature of tumor tissue and the unintended induction of muscle contractions. High-frequency IRE (H-FIRE), a new treatment modality which replaces the monopolar IRE pulses with a burst of bipolar pulses, has the potential to resolve these clinical challenges. We explored the pulse-duration space between 250 ns and 100 μs and determined the lethal electric field intensity for specific H-FIRE protocols using a 3D tumor mimic. Murine tumors were exposed to 120 bursts, each energized for 100 μs, containing individual pulses 1, 2, or 5 μs in duration. Tumor growth was significantly inhibited and all protocols were able to achieve complete regressions. The H-FIRE protocol substantially reduces muscle contractions and the therapy can be delivered without the need for a neuromuscular blockade. This work shows the potential for H-FIRE to be used as a focal therapy and merits its investigation in larger pre-clinical models.

@article{RN199,
   author = {Gallo-Villanueva, R. C. and Sano, M. B. and Lapizco-Encinas, B. H. and Davalos, R. V.},
   title = {Joule heating effects on particle immobilization in insulator-based dielectrophoretic devices},
   journal = {Electrophoresis},
   volume = {35},
   number = {2-3},
   pages = {352-61},
   note = {1522-2683
Gallo-Villanueva, Roberto C
Sano, Michael B
Lapizco-Encinas, Blanca H
Davalos, Rafael V
R21 CA173092/CA/NCI NIH HHS/United States
5R21 CA173092-01/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Germany
2013/09/05
Electrophoresis. 2014 Feb;35(2-3):352-61. doi: 10.1002/elps.201300171. Epub 2013 Oct 10.},
   abstract = {In this work, the temperature effects due to Joule heating obtained by application of a direct current electric potential were investigated for a microchannel with cylindrical insulating posts employed for insulator-based dielectrophoresis. The conductivity of the suspending medium, the local electric field, and the gradient of the squared electric field, which directly affect the magnitude of the dielectrophoretic force exerted on particles, were computationally simulated employing COMSOL Multiphysics. It was observed that a temperature gradient is formed along the microchannel, which redistributes the conductivity of the suspending medium leading to an increase of the dielectrophoretic force toward the inlet of the channel while decreasing toward the outlet. Experimental results are in good agreement with simulations on the particle-trapping zones anticipated. This study demonstrates the importance of considering Joule heating effects when designing insulator-based dielectrophoresis systems.},
   keywords = {Electric Conductivity
Electrophoresis/*instrumentation
Finite Element Analysis
*Hot Temperature
Kinetics
Microfluidic Analytical Techniques/*instrumentation
Microspheres
Dielectrophoresis
Electrokinetic
Joule heating
Microchannel},
   ISSN = {0173-0835 (Print)
0173-0835},
   DOI = {10.1002/elps.201300171},
   year = {2014},
   type = {Journal Article}
}

In this work, the temperature effects due to Joule heating obtained by application of a direct current electric potential were investigated for a microchannel with cylindrical insulating posts employed for insulator-based dielectrophoresis. The conductivity of the suspending medium, the local electric field, and the gradient of the squared electric field, which directly affect the magnitude of the dielectrophoretic force exerted on particles, were computationally simulated employing COMSOL Multiphysics. It was observed that a temperature gradient is formed along the microchannel, which redistributes the conductivity of the suspending medium leading to an increase of the dielectrophoretic force toward the inlet of the channel while decreasing toward the outlet. Experimental results are in good agreement with simulations on the particle-trapping zones anticipated. This study demonstrates the importance of considering Joule heating effects when designing insulator-based dielectrophoresis systems.

@article{RN192,
   author = {Garcia, P. A. and Davalos, R. V. and Miklavcic, D.},
   title = {A numerical investigation of the electric and thermal cell kill distributions in electroporation-based therapies in tissue},
   journal = {PLoS One},
   volume = {9},
   number = {8},
   pages = {e103083},
   note = {1932-6203
Garcia, Paulo A
Davalos, Rafael V
Miklavcic, Damijan
Journal Article
Research Support, Non-U.S. Gov't
United States
2014/08/15
PLoS One. 2014 Aug 12;9(8):e103083. doi: 10.1371/journal.pone.0103083. eCollection 2014.},
   abstract = {Electroporation-based therapies are powerful biotechnological tools for enhancing the delivery of exogeneous agents or killing tissue with pulsed electric fields (PEFs). Electrochemotherapy (ECT) and gene therapy based on gene electrotransfer (EGT) both use reversible electroporation to deliver chemotherapeutics or plasmid DNA into cells, respectively. In both ECT and EGT, the goal is to permeabilize the cell membrane while maintaining high cell viability in order to facilitate drug or gene transport into the cell cytoplasm and induce a therapeutic response. Irreversible electroporation (IRE) results in cell kill due to exposure to PEFs without drugs and is under clinical evaluation for treating otherwise unresectable tumors. These PEF therapies rely mainly on the electric field distributions and do not require changes in tissue temperature for their effectiveness. However, in immediate vicinity of the electrodes the treatment may results in cell kill due to thermal damage because of the inhomogeneous electric field distribution and high current density during the electroporation-based therapies. Therefore, the main objective of this numerical study is to evaluate the influence of pulse number and electrical conductivity in the predicted cell kill zone due to irreversible electroporation and thermal damage. Specifically, we simulated a typical IRE protocol that employs ninety 100-µs PEFs. Our results confirm that it is possible to achieve predominant cell kill due to electroporation if the PEF parameters are chosen carefully. However, if either the pulse number and/or the tissue conductivity are too high, there is also potential to achieve cell kill due to thermal damage in the immediate vicinity of the electrodes. Therefore, it is critical for physicians to be mindful of placement of electrodes with respect to critical tissue structures and treatment parameters in order to maintain the non-thermal benefits of electroporation and prevent unnecessary damage to surrounding healthy tissue, critical vascular structures, and/or adjacent organs.},
   keywords = {Algorithms
Cell Survival
Electrochemotherapy/instrumentation/*methods
Electrodes
Electroporation/instrumentation/*methods
Gene Transfer Techniques
Humans
Liver
Models, Statistical
Temperature},
   ISSN = {1932-6203},
   DOI = {10.1371/journal.pone.0103083},
   year = {2014},
   type = {Journal Article}
}

Electroporation-based therapies are powerful biotechnological tools for enhancing the delivery of exogeneous agents or killing tissue with pulsed electric fields (PEFs). Electrochemotherapy (ECT) and gene therapy based on gene electrotransfer (EGT) both use reversible electroporation to deliver chemotherapeutics or plasmid DNA into cells, respectively. In both ECT and EGT, the goal is to permeabilize the cell membrane while maintaining high cell viability in order to facilitate drug or gene transport into the cell cytoplasm and induce a therapeutic response. Irreversible electroporation (IRE) results in cell kill due to exposure to PEFs without drugs and is under clinical evaluation for treating otherwise unresectable tumors. These PEF therapies rely mainly on the electric field distributions and do not require changes in tissue temperature for their effectiveness. However, in immediate vicinity of the electrodes the treatment may results in cell kill due to thermal damage because of the inhomogeneous electric field distribution and high current density during the electroporation-based therapies. Therefore, the main objective of this numerical study is to evaluate the influence of pulse number and electrical conductivity in the predicted cell kill zone due to irreversible electroporation and thermal damage. Specifically, we simulated a typical IRE protocol that employs ninety 100-µs PEFs. Our results confirm that it is possible to achieve predominant cell kill due to electroporation if the PEF parameters are chosen carefully. However, if either the pulse number and/or the tissue conductivity are too high, there is also potential to achieve cell kill due to thermal damage in the immediate vicinity of the electrodes. Therefore, it is critical for physicians to be mindful of placement of electrodes with respect to critical tissue structures and treatment parameters in order to maintain the non-thermal benefits of electroporation and prevent unnecessary damage to surrounding healthy tissue, critical vascular structures, and/or adjacent organs.

@article{RN193,
   author = {Lapizco-Encinas, B. H. and Davalos, R. V.},
   title = {2013 AES Annual Meeting},
   journal = {Electrophoresis},
   volume = {35},
   number = {12-13},
   pages = {1767},
   note = {1522-2683
Lapizco-Encinas, Blanca H
Davalos, Rafael V
Editorial
Introductory Journal Article
Germany
2014/07/06
Electrophoresis. 2014 Jul;35(12-13):1767. doi: 10.1002/elps.201470113.},
   keywords = {*Electrophoresis
Humans
*Microfluidic Analytical Techniques},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201470113},
   year = {2014},
   type = {Journal Article}
}

@article{RN195,
   author = {Neal, R. E., 2nd and Millar, J. L. and Kavnoudias, H. and Royce, P. and Rosenfeldt, F. and Pham, A. and Smith, R. and Davalos, R. V. and Thomson, K. R.},
   title = {In vivo characterization and numerical simulation of prostate properties for non-thermal irreversible electroporation ablation},
   journal = {Prostate},
   volume = {74},
   number = {5},
   pages = {458-68},
   note = {1097-0045
Neal, Robert E 2nd
Millar, Jeremy L
Kavnoudias, Helen
Royce, Peter
Rosenfeldt, Franklin
Pham, Alan
Smith, Ryan
Davalos, Rafael V
Thomson, Kenneth R
Journal Article
Research Support, Non-U.S. Gov't
United States
2014/01/21
Prostate. 2014 May;74(5):458-68. doi: 10.1002/pros.22760. Epub 2014 Jan 17.},
   abstract = {BACKGROUND: Irreversible electroporation (IRE) delivers brief electric pulses to attain non-thermal focal ablation that spares vasculature and other sensitive systems. It is a promising prostate cancer treatment due to sparing of the tissues associated with morbidity risk from conventional therapies. IRE effects depend on electric field strength and tissue properties. These characteristics are organ-dependent, affecting IRE treatment outcomes. This study characterizes the relevant properties to improve treatment planning and outcome predictions for IRE prostate cancer treatment. METHODS: Clinically relevant IRE pulse protocols were delivered to a healthy canine and two human cancerous prostates while measuring electrical parameters to determine tissue characteristics for predictive treatment simulations. Prostates were resected 5 hr, 3 weeks, and 4 weeks post-IRE. Lesions were correlated with numerical simulations to determine an effective prostate lethal IRE electric field threshold. RESULTS: Lesions were produced in all subjects. Tissue electrical conductivity increased from 0.284 to 0.927 S/m due to IRE pulses. Numerical simulations show an average effective prostate electric field threshold of 1072 ± 119 V/cm, significantly higher than previously characterized tissues. Histological findings in the human cases show instances of complete tissue necrosis centrally with variable tissue effects beyond the margin. CONCLUSIONS: Preliminary experimental IRE trials safely ablated healthy canine and cancerous human prostates, as examined in the short- and medium-term. IRE-relevant prostate properties are now experimentally and numerically defined. Importantly, the electric field required to kill healthy prostate tissue is substantially higher than previously characterized tissues. These findings can be applied to optimize IRE prostate cancer treatment protocols.},
   keywords = {Animals
Computer Simulation
Dogs
Electric Conductivity
Electrochemotherapy/*methods
Humans
Male
Models, Biological
Prostate/pathology/*physiopathology
Prostatic Neoplasms/pathology/physiopathology/*therapy
Ire
finite element modeling
preclinical trials
prostate cancer
targeted therapy
translational research},
   ISSN = {0270-4137},
   DOI = {10.1002/pros.22760},
   year = {2014},
   type = {Journal Article}
}

BACKGROUND: Irreversible electroporation (IRE) delivers brief electric pulses to attain non-thermal focal ablation that spares vasculature and other sensitive systems. It is a promising prostate cancer treatment due to sparing of the tissues associated with morbidity risk from conventional therapies. IRE effects depend on electric field strength and tissue properties. These characteristics are organ-dependent, affecting IRE treatment outcomes. This study characterizes the relevant properties to improve treatment planning and outcome predictions for IRE prostate cancer treatment. METHODS: Clinically relevant IRE pulse protocols were delivered to a healthy canine and two human cancerous prostates while measuring electrical parameters to determine tissue characteristics for predictive treatment simulations. Prostates were resected 5 hr, 3 weeks, and 4 weeks post-IRE. Lesions were correlated with numerical simulations to determine an effective prostate lethal IRE electric field threshold. RESULTS: Lesions were produced in all subjects. Tissue electrical conductivity increased from 0.284 to 0.927 S/m due to IRE pulses. Numerical simulations show an average effective prostate electric field threshold of 1072 ± 119 V/cm, significantly higher than previously characterized tissues. Histological findings in the human cases show instances of complete tissue necrosis centrally with variable tissue effects beyond the margin. CONCLUSIONS: Preliminary experimental IRE trials safely ablated healthy canine and cancerous human prostates, as examined in the short- and medium-term. IRE-relevant prostate properties are now experimentally and numerically defined. Importantly, the electric field required to kill healthy prostate tissue is substantially higher than previously characterized tissues. These findings can be applied to optimize IRE prostate cancer treatment protocols.

@article{RN191,
   author = {Sano, M. B. and Arena, C. B. and DeWitt, M. R. and Saur, D. and Davalos, R. V.},
   title = {In-vitro bipolar nano- and microsecond electro-pulse bursts for irreversible electroporation therapies},
   journal = {Bioelectrochemistry},
   volume = {100},
   pages = {69-79},
   note = {1878-562x
Sano, Michael B
Arena, Christopher B
DeWitt, Matthew R
Saur, Dieter
Davalos, Rafael V
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Netherlands
2014/08/19
Bioelectrochemistry. 2014 Dec;100:69-79. doi: 10.1016/j.bioelechem.2014.07.010. Epub 2014 Aug 4.},
   abstract = {Under the influence of external electric fields, cells experience a rapid potential buildup across the cell membrane. Above a critical threshold of electric field strength, permanent cell damage can occur, resulting in cell death. Typical investigations of electroporation effects focus on two distinct regimes. The first uses sub-microsecond duration, high field strength pulses while the second uses longer (50 μs+) duration, but lower field strength pulses. Here we investigate the effects of pulses between these two extremes. The charging behavior of the cell membrane and nuclear envelope is evaluated numerically in response to bipolar pulses between 250 ns and 50 μs. Typical irreversible electroporation protocols expose cells to 90 monopolar pulses, each 100 μs in duration with a 1 second inter-pulse delay. Here, we replace each monopolar waveform with a burst of alternating polarity pulses, while keeping the total energized time (100 μs), burst number (80), and inter-burst delay (1s) the same. We show that these bursts result in instantaneous and delayed cell death mechanisms and that there exists an inverse relationship between pulse-width and toxicity despite the delivery of equal quantities of energy. At 1500 V/cm only treatments with bursts containing 50 μs pulses (2×) resulted in viability below 10%. At 4000 V/cm, bursts with 1 μs (100×), 2 μs (50×), 5 μs (20×), 10 μs (10×), and 50 μs (2×) duration pulses reduced viability below 10% while bursts with 500 ns (200×) and 250 ns (400×) pulses resulted in viabilities of 31% and 92%, respectively.},
   keywords = {Animals
Cell Line, Tumor
Cell Membrane
Cell Membrane Permeability
Electric Stimulation Therapy/adverse effects/*methods
Electroporation/*methods
Mice
Models, Biological
Nuclear Envelope
Time Factors
Ablation
Cancer
High frequency
Non-thermal},
   ISSN = {1567-5394},
   DOI = {10.1016/j.bioelechem.2014.07.010},
   year = {2014},
   type = {Journal Article}
}

Under the influence of external electric fields, cells experience a rapid potential buildup across the cell membrane. Above a critical threshold of electric field strength, permanent cell damage can occur, resulting in cell death. Typical investigations of electroporation effects focus on two distinct regimes. The first uses sub-microsecond duration, high field strength pulses while the second uses longer (50 μs+) duration, but lower field strength pulses. Here we investigate the effects of pulses between these two extremes. The charging behavior of the cell membrane and nuclear envelope is evaluated numerically in response to bipolar pulses between 250 ns and 50 μs. Typical irreversible electroporation protocols expose cells to 90 monopolar pulses, each 100 μs in duration with a 1 second inter-pulse delay. Here, we replace each monopolar waveform with a burst of alternating polarity pulses, while keeping the total energized time (100 μs), burst number (80), and inter-burst delay (1s) the same. We show that these bursts result in instantaneous and delayed cell death mechanisms and that there exists an inverse relationship between pulse-width and toxicity despite the delivery of equal quantities of energy. At 1500 V/cm only treatments with bursts containing 50 μs pulses (2×) resulted in viability below 10%. At 4000 V/cm, bursts with 1 μs (100×), 2 μs (50×), 5 μs (20×), 10 μs (10×), and 50 μs (2×) duration pulses reduced viability below 10% while bursts with 500 ns (200×) and 250 ns (400×) pulses resulted in viabilities of 31% and 92%, respectively.

@article{RN198,
   author = {Arena, C. B. and Mahajan, R. L. and Nichole Rylander, M. and Davalos, R. V.},
   title = {An experimental and numerical investigation of phase change electrodes for therapeutic irreversible electroporation},
   journal = {J Biomech Eng},
   volume = {135},
   number = {11},
   pages = {111009},
   note = {1528-8951
Arena, Christopher B
Mahajan, Roop L
Nichole Rylander, Marissa
Davalos, Rafael V
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
United States
2013/09/07
J Biomech Eng. 2013 Nov;135(11):111009. doi: 10.1115/1.4025334.},
   abstract = {Irreversible electroporation (IRE) is a new technology for ablating aberrant tissue that utilizes pulsed electric fields (PEFs) to kill cells by destabilizing their plasma membrane. When treatments are planned correctly, the pulse parameters and location of the electrodes for delivering the pulses are selected to permit destruction of the target tissue without causing thermal damage to the surrounding structures. This allows for the treatment of surgically inoperable masses that are located near major blood vessels and nerves. In select cases of high-dose IRE, where a large ablation volume is desired without increasing the number of electrode insertions, it can become challenging to design a pulse protocol that is inherently nonthermal. To solve this problem we have developed a new electrosurgical device that requires no external equipment or protocol modifications. The design incorporates a phase change material (PCM) into the electrode core that melts during treatment and absorbs heat out of the surrounding tissue. Here, this idea is reduced to practice by testing hollow electrodes filled with gallium on tissue phantoms and monitoring temperature in real time. Additionally, the experimental data generated are used to validate a numerical model of the heat transfer problem, which is then applied to investigate the cooling performance of other classes of PCMs. The results indicate that metallic PCMs, such as gallium, are better suited than organics or salt hydrates for thermal management, because their comparatively higher thermal conductivity aids in heat dissipation. However, the melting point of the metallic PCM must be properly adjusted to ensure that the phase transition is not completed before the end of treatment. When translated clinically, phase change electrodes have the potential to continue to allow IRE to be performed safely near critical structures, even in high-dose cases.},
   keywords = {Animals
Electrodes
Electroporation/*instrumentation
*Finite Element Analysis
Gallium
Reproducibility of Results
Temperature},
   ISSN = {0148-0731},
   DOI = {10.1115/1.4025334},
   year = {2013},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a new technology for ablating aberrant tissue that utilizes pulsed electric fields (PEFs) to kill cells by destabilizing their plasma membrane. When treatments are planned correctly, the pulse parameters and location of the electrodes for delivering the pulses are selected to permit destruction of the target tissue without causing thermal damage to the surrounding structures. This allows for the treatment of surgically inoperable masses that are located near major blood vessels and nerves. In select cases of high-dose IRE, where a large ablation volume is desired without increasing the number of electrode insertions, it can become challenging to design a pulse protocol that is inherently nonthermal. To solve this problem we have developed a new electrosurgical device that requires no external equipment or protocol modifications. The design incorporates a phase change material (PCM) into the electrode core that melts during treatment and absorbs heat out of the surrounding tissue. Here, this idea is reduced to practice by testing hollow electrodes filled with gallium on tissue phantoms and monitoring temperature in real time. Additionally, the experimental data generated are used to validate a numerical model of the heat transfer problem, which is then applied to investigate the cooling performance of other classes of PCMs. The results indicate that metallic PCMs, such as gallium, are better suited than organics or salt hydrates for thermal management, because their comparatively higher thermal conductivity aids in heat dissipation. However, the melting point of the metallic PCM must be properly adjusted to ensure that the phase transition is not completed before the end of treatment. When translated clinically, phase change electrodes have the potential to continue to allow IRE to be performed safely near critical structures, even in high-dose cases.

@article{RN197,
   author = {Elvington, E. S. and Salmanzadeh, A. and Stremler, M. A. and Davalos, R. V.},
   title = {Label-free isolation and enrichment of cells through contactless dielectrophoresis},
   journal = {J Vis Exp},
   number = {79},
   note = {1940-087x
Elvington, Elizabeth S
Salmanzadeh, Alireza
Stremler, Mark A
Davalos, Rafael V
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Video-Audio Media
United States
2013/09/24
J Vis Exp. 2013 Sep 3;(79):50634. doi: 10.3791/50634.},
   abstract = {Dielectrophoresis (DEP) is the phenomenon by which polarized particles in a non-uniform electric field undergo translational motion, and can be used to direct the motion of microparticles in a surface marker-independent manner. Traditionally, DEP devices include planar metallic electrodes patterned in the sample channel. This approach can be expensive and requires a specialized cleanroom environment. Recently, a contact-free approach called contactless dielectrophoresis (cDEP) has been developed. This method utilizes the classic principle of DEP while avoiding direct contact between electrodes and sample by patterning fluidic electrodes and a sample channel from a single polydimethylsiloxane (PDMS) substrate, and has application as a rapid microfluidic strategy designed to sort and enrich microparticles. Unique to this method is that the electric field is generated via fluidic electrode channels containing a highly conductive fluid, which are separated from the sample channel by a thin insulating barrier. Because metal electrodes do not directly contact the sample, electrolysis, electrode delamination, and sample contamination are avoided. Additionally, this enables an inexpensive and simple fabrication process. cDEP is thus well-suited for manipulating sensitive biological particles. The dielectrophoretic force acting upon the particles depends not only upon spatial gradients of the electric field generated by customizable design of the device geometry, but the intrinsic biophysical properties of the cell. As such, cDEP is a label-free technique that avoids depending upon surface-expressed molecular biomarkers that may be variably expressed within a population, while still allowing characterization, enrichment, and sorting of bioparticles. Here, we demonstrate the basics of fabrication and experimentation using cDEP. We explain the simple preparation of a cDEP chip using soft lithography techniques. We discuss the experimental procedure for characterizing crossover frequency of a particle or cell, the frequency at which the dielectrophoretic force is zero. Finally, we demonstrate the use of this technique for sorting a mixture of ovarian cancer cells and fluorescing microspheres (beads).},
   keywords = {Animals
Cell Separation/*instrumentation/*methods
Dimethylpolysiloxanes/chemistry
Electrophoresis/*instrumentation/*methods
Female
Mice
Microfluidic Analytical Techniques/instrumentation/methods
Ovarian Neoplasms/pathology},
   ISSN = {1940-087x},
   DOI = {10.3791/50634},
   year = {2013},
   type = {Journal Article}
}

Dielectrophoresis (DEP) is the phenomenon by which polarized particles in a non-uniform electric field undergo translational motion, and can be used to direct the motion of microparticles in a surface marker-independent manner. Traditionally, DEP devices include planar metallic electrodes patterned in the sample channel. This approach can be expensive and requires a specialized cleanroom environment. Recently, a contact-free approach called contactless dielectrophoresis (cDEP) has been developed. This method utilizes the classic principle of DEP while avoiding direct contact between electrodes and sample by patterning fluidic electrodes and a sample channel from a single polydimethylsiloxane (PDMS) substrate, and has application as a rapid microfluidic strategy designed to sort and enrich microparticles. Unique to this method is that the electric field is generated via fluidic electrode channels containing a highly conductive fluid, which are separated from the sample channel by a thin insulating barrier. Because metal electrodes do not directly contact the sample, electrolysis, electrode delamination, and sample contamination are avoided. Additionally, this enables an inexpensive and simple fabrication process. cDEP is thus well-suited for manipulating sensitive biological particles. The dielectrophoretic force acting upon the particles depends not only upon spatial gradients of the electric field generated by customizable design of the device geometry, but the intrinsic biophysical properties of the cell. As such, cDEP is a label-free technique that avoids depending upon surface-expressed molecular biomarkers that may be variably expressed within a population, while still allowing characterization, enrichment, and sorting of bioparticles. Here, we demonstrate the basics of fabrication and experimentation using cDEP. We explain the simple preparation of a cDEP chip using soft lithography techniques. We discuss the experimental procedure for characterizing crossover frequency of a particle or cell, the frequency at which the dielectrophoretic force is zero. Finally, we demonstrate the use of this technique for sorting a mixture of ovarian cancer cells and fluorescing microspheres (beads).

@article{RN202,
   author = {Neal, R. E., 2nd and Rossmeisl, J. H., Jr. and Robertson, J. L. and Arena, C. B. and Davis, E. M. and Singh, R. N. and Stallings, J. and Davalos, R. V.},
   title = {Improved local and systemic anti-tumor efficacy for irreversible electroporation in immunocompetent versus immunodeficient mice},
   journal = {PLoS One},
   volume = {8},
   number = {5},
   pages = {e64559},
   note = {1932-6203
Neal, Robert E 2nd
Rossmeisl, John H Jr
Robertson, John L
Arena, Christopher B
Davis, Erica M
Singh, Ravi N
Stallings, Jonathan
Davalos, Rafael V
K99 CA154006/CA/NCI NIH HHS/United States
R00 CA154006/CA/NCI NIH HHS/United States
K99CA154006/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2013/05/30
PLoS One. 2013 May 24;8(5):e64559. doi: 10.1371/journal.pone.0064559. Print 2013.},
   abstract = {Irreversible electroporation (IRE) is a non-thermal focal ablation technique that uses a series of brief but intense electric pulses delivered into a targeted region of tissue, killing the cells by irrecoverably disrupting cellular membrane integrity. This study investigates if there is an improved local anti-tumor response in immunocompetent (IC) BALB/c versus immunodeficient (ID) nude mice, including the potential for a systemic protective effect against rechallenge. Subcutaneous murine renal carcinoma tumors were treated with an IRE pulsing protocol that used 60% of the predicted voltage required to invoke complete regressions in the ID mice. Tumors were followed for 34 days following treatment for 11 treated mice from each strain, and 7 controls from each strain. Mouse survival based on tumor burden and the progression-free disease period was substantially longer in the treated IC mice relative to the treated ID mice and sham controls for both strains. Treated IC mice were rechallenged with the same cell line 18 days after treatment, where growth of the second tumors was shown to be significantly reduced or prevented entirely. There was robust CD3+ cell infiltration in some treated BALB/C mice, with immunocytes focused at the transition between viable and dead tumor. There was no difference in the low immunocyte presence for untreated tumors, nude mice, and matrigel-only injections in both strains. These findings suggest IRE therapy may have greater therapeutic efficacy in immunocompetent patients than what has been suggested by immunodeficient models, and that IRE may invoke a systemic response beyond the targeted ablation region.},
   keywords = {Animals
Cell Line, Tumor
*Electroporation
Female
Immunocompromised Host
Mice
Mice, Inbred BALB C
Mice, Nude
Neoplasms/*immunology/mortality/*pathology
Tumor Burden/immunology},
   ISSN = {1932-6203},
   DOI = {10.1371/journal.pone.0064559},
   year = {2013},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a non-thermal focal ablation technique that uses a series of brief but intense electric pulses delivered into a targeted region of tissue, killing the cells by irrecoverably disrupting cellular membrane integrity. This study investigates if there is an improved local anti-tumor response in immunocompetent (IC) BALB/c versus immunodeficient (ID) nude mice, including the potential for a systemic protective effect against rechallenge. Subcutaneous murine renal carcinoma tumors were treated with an IRE pulsing protocol that used 60% of the predicted voltage required to invoke complete regressions in the ID mice. Tumors were followed for 34 days following treatment for 11 treated mice from each strain, and 7 controls from each strain. Mouse survival based on tumor burden and the progression-free disease period was substantially longer in the treated IC mice relative to the treated ID mice and sham controls for both strains. Treated IC mice were rechallenged with the same cell line 18 days after treatment, where growth of the second tumors was shown to be significantly reduced or prevented entirely. There was robust CD3+ cell infiltration in some treated BALB/C mice, with immunocytes focused at the transition between viable and dead tumor. There was no difference in the low immunocyte presence for untreated tumors, nude mice, and matrigel-only injections in both strains. These findings suggest IRE therapy may have greater therapeutic efficacy in immunocompetent patients than what has been suggested by immunodeficient models, and that IRE may invoke a systemic response beyond the targeted ablation region.

@article{RN200,
   author = {Neal, R. E., 2nd and Smith, R. L. and Kavnoudias, H. and Rosenfeldt, F. and Ou, R. and McLean, C. A. and Davalos, R. V. and Thomson, K. R.},
   title = {The effects of metallic implants on electroporation therapies: feasibility of irreversible electroporation for brachytherapy salvage},
   journal = {Cardiovasc Intervent Radiol},
   volume = {36},
   number = {6},
   pages = {1638-1645},
   note = {1432-086x
Neal, Robert E 2nd
Smith, Ryan L
Kavnoudias, Helen
Rosenfeldt, Franklin
Ou, Ruchong
Mclean, Catriona A
Davalos, Rafael V
Thomson, Kenneth R
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2013/08/15
Cardiovasc Intervent Radiol. 2013 Dec;36(6):1638-1645. doi: 10.1007/s00270-013-0704-1. Epub 2013 Aug 14.},
   abstract = {PURPOSE: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. MATERIALS AND METHODS: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. RESULTS: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. CONCLUSION: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.},
   keywords = {Animals
Brachytherapy/*methods
Catheter Ablation/methods
Dogs
Electric Conductivity
Electrochemotherapy/*methods
Electroporation/*methods
Feasibility Studies
Male
*Metals
Models, Biological
Models, Theoretical
*Prostate
Salvage Therapy/*methods
Solanum tuberosum},
   ISSN = {0174-1551},
   DOI = {10.1007/s00270-013-0704-1},
   year = {2013},
   type = {Journal Article}
}

PURPOSE: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. MATERIALS AND METHODS: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. RESULTS: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. CONCLUSION: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

@article{RN201,
   author = {Rossmeisl, J. H., Jr. and Garcia, P. A. and Roberston, J. L. and Ellis, T. L. and Davalos, R. V.},
   title = {Pathology of non-thermal irreversible electroporation (N-TIRE)-induced ablation of the canine brain},
   journal = {J Vet Sci},
   volume = {14},
   number = {4},
   pages = {433-40},
   note = {1976-555x
Rossmeisl, John H Jr
Garcia, Paulo A
Roberston, John L
Ellis, Thomas L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Korea (South)
2013/07/04
J Vet Sci. 2013;14(4):433-40. doi: 10.4142/jvs.2013.14.4.433. Epub 2013 Jun 28.},
   abstract = {This study describes the neuropathologic features of normal canine brain ablated with non-thermal irreversible electroporation (N-TIRE). The parietal cerebral cortices of four dogs were treated with N-TIRE using a dose-escalation protocol with an additional dog receiving sham treatment. Animals were allowed to recover following N-TIRE ablation and the effects of treatment were monitored with clinical and magnetic resonance imaging examinations. Brains were subjected to histopathologic and ultrastructural assessment along with Bcl-2, caspase-3, and caspase-9 immunohistochemical staining following sacrifice 72 h post-treatment. Adverse clinical effects of N-TIRE were only observed in the dog treated at the upper energy tier. MRI and neuropathologic examinations indicated that N-TIRE ablation resulted in focal regions of severe cytoarchitectural and blood-brain-barrier disruption. Lesion size correlated to the intensity of the applied electrical field. N-TIRE-induced lesions were characterized by parenchymal necrosis and hemorrhage; however, large blood vessels were preserved. A transition zone containing parenchymal edema, perivascular inflammatory cuffs, and reactive gliosis was interspersed between the necrotic focus and normal neuropil. Apoptotic labeling indices were not different between the N-TIRE-treated and control brains. This study identified N-TIRE pulse parameters that can be used to safely create circumscribed foci of brain necrosis while selectively preserving major vascular structures.},
   keywords = {Animals
Brain/metabolism/*pathology/surgery/ultrastructure
Caspase 3/metabolism
Caspase 9/metabolism
Dogs
Electroporation/veterinary
Magnetic Resonance Imaging/methods
Microscopy, Electron, Transmission
Necrosis/metabolism/pathology
Neurosurgical Procedures/*adverse effects
central nervous system
dog
irreversible electroporation
neuropathology},
   ISSN = {1229-845X (Print)
1229-845x},
   DOI = {10.4142/jvs.2013.14.4.433},
   year = {2013},
   type = {Journal Article}
}

This study describes the neuropathologic features of normal canine brain ablated with non-thermal irreversible electroporation (N-TIRE). The parietal cerebral cortices of four dogs were treated with N-TIRE using a dose-escalation protocol with an additional dog receiving sham treatment. Animals were allowed to recover following N-TIRE ablation and the effects of treatment were monitored with clinical and magnetic resonance imaging examinations. Brains were subjected to histopathologic and ultrastructural assessment along with Bcl-2, caspase-3, and caspase-9 immunohistochemical staining following sacrifice 72 h post-treatment. Adverse clinical effects of N-TIRE were only observed in the dog treated at the upper energy tier. MRI and neuropathologic examinations indicated that N-TIRE ablation resulted in focal regions of severe cytoarchitectural and blood-brain-barrier disruption. Lesion size correlated to the intensity of the applied electrical field. N-TIRE-induced lesions were characterized by parenchymal necrosis and hemorrhage; however, large blood vessels were preserved. A transition zone containing parenchymal edema, perivascular inflammatory cuffs, and reactive gliosis was interspersed between the necrotic focus and normal neuropil. Apoptotic labeling indices were not different between the N-TIRE-treated and control brains. This study identified N-TIRE pulse parameters that can be used to safely create circumscribed foci of brain necrosis while selectively preserving major vascular structures.

@article{RN203,
   author = {Salmanzadeh, A. and Elvington, E. S. and Roberts, P. C. and Schmelz, E. M. and Davalos, R. V.},
   title = {Sphingolipid metabolites modulate dielectric characteristics of cells in a mouse ovarian cancer progression model},
   journal = {Integr Biol (Camb)},
   volume = {5},
   number = {6},
   pages = {843-52},
   note = {1757-9708
Salmanzadeh, Alireza
Elvington, Elizabeth S
Roberts, Paul C
Schmelz, Eva M
Davalos, Rafael V
R21 CA173092/CA/NCI NIH HHS/United States
R01 CA118846/CA/NCI NIH HHS/United States
1R21 CA173092-01/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2013/04/24
Integr Biol (Camb). 2013 Jun;5(6):843-52. doi: 10.1039/c3ib00008g.},
   abstract = {Currently, conventional cancer treatment regimens often rely upon highly toxic chemotherapeutics or target oncogenes that are variably expressed within the heterogeneous cell population of tumors. These challenges highlight the need for novel treatment strategies that (1) are non-toxic yet able to at least partially reverse the aggressive phenotype of the disease to a benign or very slow-growing state, and (2) act on the cells independently of variably expressed biomarkers. Using a label-independent rapid microfluidic cell manipulation strategy known as contactless dielectrophoresis (cDEP), we investigated the effect of non-toxic concentrations of two bioactive sphingolipid metabolites, sphingosine (So), with potential anti-tumor properties, and sphingosine-1-phosphate (S1P), a tumor-promoting metabolite, on the intrinsic electrical properties of early and late stages of mouse ovarian surface epithelial (MOSE) cancer cells. Previously, we demonstrated that electrical properties change as cells progress from a benign early stage to late malignant stages. Here, we demonstrate an association between So treatment and a shift in the bioelectrical characteristics of late stage MOSE (MOSE-L) cells towards a profile similar to that of benign MOSE-E cells. Particularly, the specific membrane capacitance of MOSE-L cells shifted toward that of MOSE-E cells, decreasing from 23.94 ± 2.75 to 16.46 ± 0.62 mF m(-2) after So treatment, associated with a decrease in membrane protrusions. In contrast, S1P did not reverse the electrical properties of MOSE-L cells. This work is the first to indicate that treatment with non-toxic doses of So correlates with changes in the electrical properties and surface roughness of cells. It also demonstrates the potential of cDEP to be used as a new, rapid technique for drug efficacy studies, and for eventually designing more personalized treatment regimens.},
   keywords = {Animals
Carcinoma, Ovarian Epithelial
Cell Line, Tumor
Disease Progression
Electrophoresis
Female
Lysophospholipids/*metabolism
Mice
Microfluidics
*Models, Biological
Neoplasms, Glandular and Epithelial/*metabolism/*pathology
Ovarian Neoplasms/*metabolism/*pathology
Phenotype
Sphingosine/*analogs & derivatives/*metabolism},
   ISSN = {1757-9694 (Print)
1757-9694},
   DOI = {10.1039/c3ib00008g},
   year = {2013},
   type = {Journal Article}
}

Currently, conventional cancer treatment regimens often rely upon highly toxic chemotherapeutics or target oncogenes that are variably expressed within the heterogeneous cell population of tumors. These challenges highlight the need for novel treatment strategies that (1) are non-toxic yet able to at least partially reverse the aggressive phenotype of the disease to a benign or very slow-growing state, and (2) act on the cells independently of variably expressed biomarkers. Using a label-independent rapid microfluidic cell manipulation strategy known as contactless dielectrophoresis (cDEP), we investigated the effect of non-toxic concentrations of two bioactive sphingolipid metabolites, sphingosine (So), with potential anti-tumor properties, and sphingosine-1-phosphate (S1P), a tumor-promoting metabolite, on the intrinsic electrical properties of early and late stages of mouse ovarian surface epithelial (MOSE) cancer cells. Previously, we demonstrated that electrical properties change as cells progress from a benign early stage to late malignant stages. Here, we demonstrate an association between So treatment and a shift in the bioelectrical characteristics of late stage MOSE (MOSE-L) cells towards a profile similar to that of benign MOSE-E cells. Particularly, the specific membrane capacitance of MOSE-L cells shifted toward that of MOSE-E cells, decreasing from 23.94 ± 2.75 to 16.46 ± 0.62 mF m(-2) after So treatment, associated with a decrease in membrane protrusions. In contrast, S1P did not reverse the electrical properties of MOSE-L cells. This work is the first to indicate that treatment with non-toxic doses of So correlates with changes in the electrical properties and surface roughness of cells. It also demonstrates the potential of cDEP to be used as a new, rapid technique for drug efficacy studies, and for eventually designing more personalized treatment regimens.

@article{RN196,
   author = {Salmanzadeh, A. and Sano, M. B. and Gallo-Villanueva, R. C. and Roberts, P. C. and Schmelz, E. M. and Davalos, R. V.},
   title = {Investigating dielectric properties of different stages of syngeneic murine ovarian cancer cells},
   journal = {Biomicrofluidics},
   volume = {7},
   number = {1},
   pages = {11809},
   note = {1932-1058
Salmanzadeh, Alireza
Sano, Michael B
Gallo-Villanueva, Roberto C
Roberts, Paul C
Schmelz, Eva M
Davalos, Rafael V
R01 CA118846/CA/NCI NIH HHS/United States
Journal Article
United States
2014/01/10
Biomicrofluidics. 2013 Jan 23;7(1):11809. doi: 10.1063/1.4788921. eCollection 2013.},
   abstract = {In this study, the electrical properties of four different stages of mouse ovarian surface epithelial (MOSE) cells were investigated using contactless dielectrophoresis (cDEP). This study expands the work from our previous report describing for the first time the crossover frequency and cell specific membrane capacitance of different stages of cancer cells that are derived from the same cell line. The specific membrane capacitance increased as the stage of malignancy advanced from 15.39 ± 1.54 mF m(-2) for a non-malignant benign stage to 26.42 ± 1.22 mF m(-2) for the most aggressive stage. These differences could be the result of morphological variations due to changes in the cytoskeleton structure, specifically the decrease of the level of actin filaments in the cytoskeleton structure of the transformed MOSE cells. Studying the electrical properties of MOSE cells provides important information as a first step to develop cancer-treatment techniques which could partially reverse the cytoskeleton disorganization of malignant cells to a morphology more similar to that of benign cells.},
   ISSN = {1932-1058 (Print)
1932-1058},
   DOI = {10.1063/1.4788921},
   year = {2013},
   type = {Journal Article}
}

In this study, the electrical properties of four different stages of mouse ovarian surface epithelial (MOSE) cells were investigated using contactless dielectrophoresis (cDEP). This study expands the work from our previous report describing for the first time the crossover frequency and cell specific membrane capacitance of different stages of cancer cells that are derived from the same cell line. The specific membrane capacitance increased as the stage of malignancy advanced from 15.39 ± 1.54 mF m(-2) for a non-malignant benign stage to 26.42 ± 1.22 mF m(-2) for the most aggressive stage. These differences could be the result of morphological variations due to changes in the cytoskeleton structure, specifically the decrease of the level of actin filaments in the cytoskeleton structure of the transformed MOSE cells. Studying the electrical properties of MOSE cells provides important information as a first step to develop cancer-treatment techniques which could partially reverse the cytoskeleton disorganization of malignant cells to a morphology more similar to that of benign cells.

@article{RN207,
   author = {Arena, C. B. and Szot, C. S. and Garcia, P. A. and Rylander, M. N. and Davalos, R. V.},
   title = {A three-dimensional in vitro tumor platform for modeling therapeutic irreversible electroporation},
   journal = {Biophys J},
   volume = {103},
   number = {9},
   pages = {2033-42},
   note = {1542-0086
Arena, Christopher B
Szot, Christopher S
Garcia, Paulo A
Rylander, Marissa Nichole
Davalos, Rafael V
R21 CA158454/CA/NCI NIH HHS/United States
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
United States
2012/12/04
Biophys J. 2012 Nov 7;103(9):2033-42. doi: 10.1016/j.bpj.2012.09.017.},
   abstract = {Irreversible electroporation (IRE) is emerging as a powerful tool for tumor ablation that utilizes pulsed electric fields to destabilize the plasma membrane of cancer cells past the point of recovery. The ablated region is dictated primarily by the electric field distribution in the tissue, which forms the basis of current treatment planning algorithms. To generate data for refinement of these algorithms, there is a need to develop a physiologically accurate and reproducible platform on which to study IRE in vitro. Here, IRE was performed on a 3D in vitro tumor model consisting of cancer cells cultured within dense collagen I hydrogels, which have been shown to acquire phenotypes and respond to therapeutic stimuli in a manner analogous to that observed in in vivo pathological systems. Electrical and thermal fluctuations were monitored during treatment, and this information was incorporated into a numerical model for predicting the electric field distribution in the tumors. When correlated with Live/Dead staining of the tumors, an electric field threshold for cell death (500 V/cm) comparable to values reported in vivo was generated. In addition, submillimeter resolution was observed at the boundary between the treated and untreated regions, which is characteristic of in vivo IRE. Overall, these results illustrate the advantages of using 3D cancer cell culture models to improve IRE-treatment planning and facilitate widespread clinical use of the technology.},
   keywords = {Animals
Cell Death
Cell Line, Tumor
Collagen Type I
Electromagnetic Fields
*Electroporation
Hydrogels
Mice
Neoplasms, Experimental/*therapy
Phenotype
Temperature},
   ISSN = {0006-3495 (Print)
0006-3495},
   DOI = {10.1016/j.bpj.2012.09.017},
   year = {2012},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is emerging as a powerful tool for tumor ablation that utilizes pulsed electric fields to destabilize the plasma membrane of cancer cells past the point of recovery. The ablated region is dictated primarily by the electric field distribution in the tissue, which forms the basis of current treatment planning algorithms. To generate data for refinement of these algorithms, there is a need to develop a physiologically accurate and reproducible platform on which to study IRE in vitro. Here, IRE was performed on a 3D in vitro tumor model consisting of cancer cells cultured within dense collagen I hydrogels, which have been shown to acquire phenotypes and respond to therapeutic stimuli in a manner analogous to that observed in in vivo pathological systems. Electrical and thermal fluctuations were monitored during treatment, and this information was incorporated into a numerical model for predicting the electric field distribution in the tumors. When correlated with Live/Dead staining of the tumors, an electric field threshold for cell death (500 V/cm) comparable to values reported in vivo was generated. In addition, submillimeter resolution was observed at the boundary between the treated and untreated regions, which is characteristic of in vivo IRE. Overall, these results illustrate the advantages of using 3D cancer cell culture models to improve IRE-treatment planning and facilitate widespread clinical use of the technology.

@article{RN204,
   author = {Garcia, P. A. and Arena, C. B. and Davalos, R. V.},
   title = {Towards a predictive model of electroporation-based therapies using pre-pulse electrical measurements},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2012},
   pages = {2575-8},
   note = {2694-0604
Garcia, Paulo A
Arena, Christopher B
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2013/02/01
Annu Int Conf IEEE Eng Med Biol Soc. 2012;2012:2575-8. doi: 10.1109/EMBC.2012.6346490.},
   abstract = {Electroporation-based therapies have been gaining momentum as minimally invasive techniques to facilitate transport of exogenous agents, or directly kill tumors and other undesirable tissue in a non-thermal manner. Typical procedures involve placing electrodes into or around the treatment area and delivering a series of short and intense electric pulses to the tissue/tumor. These pulses create defects in the cell membranes, inducing non-linear changes in the electric conductivity of the tissue. These dynamic conductivity changes redistribute the electric field, and thus the treatment volume. In this study, we develop a statistical model that can be used to determine the baseline conductivity of tissues prior to electroporation and is capable of predicting the non-linear current response with implications for treatment planning and outcome confirmation.},
   keywords = {Algorithms
Electric Conductivity
Electrochemotherapy/*methods
Electroporation
Humans},
   ISSN = {2375-7477},
   DOI = {10.1109/embc.2012.6346490},
   year = {2012},
   type = {Journal Article}
}

Electroporation-based therapies have been gaining momentum as minimally invasive techniques to facilitate transport of exogenous agents, or directly kill tumors and other undesirable tissue in a non-thermal manner. Typical procedures involve placing electrodes into or around the treatment area and delivering a series of short and intense electric pulses to the tissue/tumor. These pulses create defects in the cell membranes, inducing non-linear changes in the electric conductivity of the tissue. These dynamic conductivity changes redistribute the electric field, and thus the treatment volume. In this study, we develop a statistical model that can be used to determine the baseline conductivity of tissues prior to electroporation and is capable of predicting the non-linear current response with implications for treatment planning and outcome confirmation.

@article{RN206,
   author = {Garcia, P. A. and Rossmeisl, J. H., Jr. and Robertson, J. L. and Olson, J. D. and Johnson, A. J. and Ellis, T. L. and Davalos, R. V.},
   title = {7.0-T magnetic resonance imaging characterization of acute blood-brain-barrier disruption achieved with intracranial irreversible electroporation},
   journal = {PLoS One},
   volume = {7},
   number = {11},
   pages = {e50482},
   note = {1932-6203
Garcia, Paulo A
Rossmeisl, John H Jr
Robertson, John L
Olson, John D
Johnson, Annette J
Ellis, Thomas L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2012/12/12
PLoS One. 2012;7(11):e50482. doi: 10.1371/journal.pone.0050482. Epub 2012 Nov 30.},
   abstract = {The blood-brain-barrier (BBB) presents a significant obstacle to the delivery of systemically administered chemotherapeutics for the treatment of brain cancer. Irreversible electroporation (IRE) is an emerging technology that uses pulsed electric fields for the non-thermal ablation of tumors. We hypothesized that there is a minimal electric field at which BBB disruption occurs surrounding an IRE-induced zone of ablation and that this transient response can be measured using gadolinium (Gd) uptake as a surrogate marker for BBB disruption. The study was performed in a Good Laboratory Practices (GLP) compliant facility and had Institutional Animal Care and Use Committee (IACUC) approval. IRE ablations were performed in vivo in normal rat brain (n = 21) with 1-mm electrodes (0.45 mm diameter) separated by an edge-to-edge distance of 4 mm. We used an ECM830 pulse generator to deliver ninety 50-μs pulse treatments (0, 200, 400, 600, 800, and 1000 V/cm) at 1 Hz. The effects of applied electric fields and timing of Gd administration (-5, +5, +15, and +30 min) was assessed by systematically characterizing IRE-induced regions of cell death and BBB disruption with 7.0-T magnetic resonance imaging (MRI) and histopathologic evaluations. Statistical analysis on the effect of applied electric field and Gd timing was conducted via Fit of Least Squares with α = 0.05 and linear regression analysis. The focal nature of IRE treatment was confirmed with 3D MRI reconstructions with linear correlations between volume of ablation and electric field. Our results also demonstrated that IRE is an ablation technique that kills brain tissue in a focal manner depicted by MRI (n = 16) and transiently disrupts the BBB adjacent to the ablated area in a voltage-dependent manner as seen with Evan's Blue (n = 5) and Gd administration.},
   keywords = {Ablation Techniques
Animals
Biological Transport
Blood-Brain Barrier/*metabolism
Disease Susceptibility
Electroporation/*methods
Gadolinium/metabolism
Glioblastoma/metabolism/therapy
*Magnetic Resonance Imaging
Male
Rats
Rats, Inbred F344
*Skull},
   ISSN = {1932-6203},
   DOI = {10.1371/journal.pone.0050482},
   year = {2012},
   type = {Journal Article}
}

The blood-brain-barrier (BBB) presents a significant obstacle to the delivery of systemically administered chemotherapeutics for the treatment of brain cancer. Irreversible electroporation (IRE) is an emerging technology that uses pulsed electric fields for the non-thermal ablation of tumors. We hypothesized that there is a minimal electric field at which BBB disruption occurs surrounding an IRE-induced zone of ablation and that this transient response can be measured using gadolinium (Gd) uptake as a surrogate marker for BBB disruption. The study was performed in a Good Laboratory Practices (GLP) compliant facility and had Institutional Animal Care and Use Committee (IACUC) approval. IRE ablations were performed in vivo in normal rat brain (n = 21) with 1-mm electrodes (0.45 mm diameter) separated by an edge-to-edge distance of 4 mm. We used an ECM830 pulse generator to deliver ninety 50-μs pulse treatments (0, 200, 400, 600, 800, and 1000 V/cm) at 1 Hz. The effects of applied electric fields and timing of Gd administration (-5, +5, +15, and +30 min) was assessed by systematically characterizing IRE-induced regions of cell death and BBB disruption with 7.0-T magnetic resonance imaging (MRI) and histopathologic evaluations. Statistical analysis on the effect of applied electric field and Gd timing was conducted via Fit of Least Squares with α = 0.05 and linear regression analysis. The focal nature of IRE treatment was confirmed with 3D MRI reconstructions with linear correlations between volume of ablation and electric field. Our results also demonstrated that IRE is an ablation technique that kills brain tissue in a focal manner depicted by MRI (n = 16) and transiently disrupts the BBB adjacent to the ablated area in a voltage-dependent manner as seen with Evan's Blue (n = 5) and Gd administration.

@article{RN214,
   author = {Neal, R. E., 2nd and Garcia, P. A. and Robertson, J. L. and Davalos, R. V.},
   title = {Experimental characterization and numerical modeling of tissue electrical conductivity during pulsed electric fields for irreversible electroporation treatment planning},
   journal = {IEEE Trans Biomed Eng},
   volume = {59},
   number = {4},
   pages = {1076-85},
   note = {1558-2531
Neal, Robert E 2nd
Garcia, Paulo A
Robertson, John L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2012/01/11
IEEE Trans Biomed Eng. 2012 Apr;59(4):1076-85. doi: 10.1109/TBME.2012.2182994. Epub 2012 Jan 6.},
   abstract = {Irreversible electroporation is a new technique to kill cells in targeted tissue, such as tumors, through a nonthermal mechanism using electric pulses to irrecoverably disrupt the cell membrane. Treatment effects relate to the tissue electric field distribution, which can be predicted with numerical modeling for therapy planning. Pulse effects will change the cell and tissue properties through thermal and electroporation (EP)-based processes. This investigation characterizes these changes by measuring the electrical conductivity and temperature of ex vivo renal porcine tissue within a single pulse and for a 200 pulse protocol. These changes are incorporated into an equivalent circuit model for cells and tissue with a variable EP-based resistance, providing a potential method to estimate conductivity as a function of electric field and pulse length for other tissues. Finally, a numerical model using a human kidney volumetric mesh evaluated how treatment predictions vary when EP- and temperature-based electrical conductivity changes are incorporated. We conclude that significant changes in predicted outcomes will occur when the experimental results are applied to the numerical model, where the direction and degree of change varies with the electric field considered.},
   keywords = {Animals
Cell Membrane Permeability/*physiology/*radiation effects
Computer Simulation
Dose-Response Relationship, Radiation
Electric Conductivity
Electromagnetic Fields
Electroporation/*methods
Kidney/*physiology/*radiation effects
*Models, Biological
Radiation Dosage
Swine},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2012.2182994},
   year = {2012},
   type = {Journal Article}
}

Irreversible electroporation is a new technique to kill cells in targeted tissue, such as tumors, through a nonthermal mechanism using electric pulses to irrecoverably disrupt the cell membrane. Treatment effects relate to the tissue electric field distribution, which can be predicted with numerical modeling for therapy planning. Pulse effects will change the cell and tissue properties through thermal and electroporation (EP)-based processes. This investigation characterizes these changes by measuring the electrical conductivity and temperature of ex vivo renal porcine tissue within a single pulse and for a 200 pulse protocol. These changes are incorporated into an equivalent circuit model for cells and tissue with a variable EP-based resistance, providing a potential method to estimate conductivity as a function of electric field and pulse length for other tissues. Finally, a numerical model using a human kidney volumetric mesh evaluated how treatment predictions vary when EP- and temperature-based electrical conductivity changes are incorporated. We conclude that significant changes in predicted outcomes will occur when the experimental results are applied to the numerical model, where the direction and degree of change varies with the electric field considered.

@article{RN210,
   author = {Salmanzadeh, A. and Kittur, H. and Sano, M. B. and P, C. Roberts and Schmelz, E. M. and Davalos, R. V.},
   title = {Dielectrophoretic differentiation of mouse ovarian surface epithelial cells, macrophages, and fibroblasts using contactless dielectrophoresis},
   journal = {Biomicrofluidics},
   volume = {6},
   number = {2},
   pages = {24104-2410413},
   note = {1932-1058
Salmanzadeh, Alireza
Kittur, Harsha
Sano, Michael B
C Roberts, Paul
Schmelz, Eva M
Davalos, Rafael V
R01 CA118846/CA/NCI NIH HHS/United States
Journal Article
United States
2012/04/27
Biomicrofluidics. 2012 Jun;6(2):24104-2410413. doi: 10.1063/1.3699973. Epub 2012 Apr 3.},
   abstract = {Ovarian cancer is the leading cause of death from gynecological malignancies in women. The primary challenge is the detection of the cancer at an early stage, since this drastically increases the survival rate. In this study we investigated the dielectrophoretic responses of progressive stages of mouse ovarian surface epithelial (MOSE) cells, as well as mouse fibroblast and macrophage cell lines, utilizing contactless dielectrophoresis (cDEP). cDEP is a relatively new cell manipulation technique that has addressed some of the challenges of conventional dielectrophoretic methods. To evaluate our microfluidic device performance, we computationally studied the effects of altering various geometrical parameters, such as the size and arrangement of insulating structures, on dielectrophoretic and drag forces. We found that the trapping voltage of MOSE cells increases as the cells progress from a non-tumorigenic, benign cell to a tumorigenic, malignant phenotype. Additionally, all MOSE cells display unique behavior compared to fibroblasts and macrophages, representing normal and inflammatory cells found in the peritoneal fluid. Based on these findings, we predict that cDEP can be utilized for isolation of ovarian cancer cells from peritoneal fluid as an early cancer detection tool.},
   ISSN = {1932-1058 (Print)
1932-1058},
   DOI = {10.1063/1.3699973},
   year = {2012},
   type = {Journal Article}
}

Ovarian cancer is the leading cause of death from gynecological malignancies in women. The primary challenge is the detection of the cancer at an early stage, since this drastically increases the survival rate. In this study we investigated the dielectrophoretic responses of progressive stages of mouse ovarian surface epithelial (MOSE) cells, as well as mouse fibroblast and macrophage cell lines, utilizing contactless dielectrophoresis (cDEP). cDEP is a relatively new cell manipulation technique that has addressed some of the challenges of conventional dielectrophoretic methods. To evaluate our microfluidic device performance, we computationally studied the effects of altering various geometrical parameters, such as the size and arrangement of insulating structures, on dielectrophoretic and drag forces. We found that the trapping voltage of MOSE cells increases as the cells progress from a non-tumorigenic, benign cell to a tumorigenic, malignant phenotype. Additionally, all MOSE cells display unique behavior compared to fibroblasts and macrophages, representing normal and inflammatory cells found in the peritoneal fluid. Based on these findings, we predict that cDEP can be utilized for isolation of ovarian cancer cells from peritoneal fluid as an early cancer detection tool.

@article{RN217,
   author = {Salmanzadeh, A. and Romero, L. and Shafiee, H. and Gallo-Villanueva, R. C. and Stremler, M. A. and Cramer, S. D. and Davalos, R. V.},
   title = {Isolation of prostate tumor initiating cells (TICs) through their dielectrophoretic signature},
   journal = {Lab Chip},
   volume = {12},
   number = {1},
   pages = {182-9},
   note = {1473-0189
Salmanzadeh, Alireza
Romero, Lina
Shafiee, Hadi
Gallo-Villanueva, Roberto C
Stremler, Mark A
Cramer, Scott D
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2011/11/10
Lab Chip. 2012 Jan 7;12(1):182-9. doi: 10.1039/c1lc20701f. Epub 2011 Nov 9.},
   abstract = {In this study, the dielectrophoretic response of prostate tumor initiating cells (TICs) was investigated in a microfluidic system utilizing contactless dielectrophoresis (cDEP). The dielectrophoretic response of prostate TICs was observed to be distinctively different than that for non-TICs, enabling them to be sorted using cDEP. Culturing the sorted TICs generated spheroids, indicating that they were indeed initiating cells. This study presents the first marker-free TIC separation from non-TICs utilizing their electrical fingerprints through dielectrophoresis.},
   keywords = {Cell Separation/*instrumentation/methods
Cell Survival
Computer Simulation
Electrophoresis/*instrumentation
Flow Cytometry
Humans
Male
Microfluidic Analytical Techniques/*instrumentation
Neoplastic Stem Cells/*chemistry/pathology
Prostatic Neoplasms/chemistry/*pathology
Reproducibility of Results
Spheroids, Cellular/chemistry/cytology
Tumor Cells, Cultured},
   ISSN = {1473-0189},
   DOI = {10.1039/c1lc20701f},
   year = {2012},
   type = {Journal Article}
}

In this study, the dielectrophoretic response of prostate tumor initiating cells (TICs) was investigated in a microfluidic system utilizing contactless dielectrophoresis (cDEP). The dielectrophoretic response of prostate TICs was observed to be distinctively different than that for non-TICs, enabling them to be sorted using cDEP. Culturing the sorted TICs generated spheroids, indicating that they were indeed initiating cells. This study presents the first marker-free TIC separation from non-TICs utilizing their electrical fingerprints through dielectrophoresis.

@article{RN205,
   author = {Salmanzadeh, A. and Sano, M. B. and Shafiee, H. and Stremler, M. A. and Davalos, R. V.},
   title = {Isolation of rare cancer cells from blood cells using dielectrophoresis},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2012},
   pages = {590-3},
   note = {2694-0604
Salmanzadeh, Alireza
Sano, Michael B
Shafiee, Hadi
Stremler, Mark A
Davalos, Rafael V
Evaluation Study
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.
United States
2013/02/01
Annu Int Conf IEEE Eng Med Biol Soc. 2012;2012:590-3. doi: 10.1109/EMBC.2012.6346000.},
   abstract = {In this study, we investigate the application of contactless dielectrophoresis (cDEP) for isolating cancer cells from blood cells. Devices with throughput of 0.2 mL/hr (equivalent to sorting 3×10(6) cells per minute) were used to trap breast cancer cells while allowing blood cells through. We have shown that this technique is able to isolate cancer cells in concentration as low as 1 cancer cell per 10(6) hematologic cells (equivalent to 1000 cancer cells in 1 mL of blood). We achieved 96% trapping of the cancer cells at 600 kHz and 300 V(RMS).},
   keywords = {Blood Cells/pathology
Breast Neoplasms/blood/pathology
Cell Line, Tumor
Cell Separation/instrumentation/*methods
Electrodes
Electrophoresis/instrumentation/*methods
Equipment Design
Female
Humans
Microfluidic Analytical Techniques/instrumentation/methods
Neoplastic Cells, Circulating/*pathology},
   ISSN = {2375-7477},
   DOI = {10.1109/embc.2012.6346000},
   year = {2012},
   type = {Journal Article}
}

In this study, we investigate the application of contactless dielectrophoresis (cDEP) for isolating cancer cells from blood cells. Devices with throughput of 0.2 mL/hr (equivalent to sorting 3×10(6) cells per minute) were used to trap breast cancer cells while allowing blood cells through. We have shown that this technique is able to isolate cancer cells in concentration as low as 1 cancer cell per 10(6) hematologic cells (equivalent to 1000 cancer cells in 1 mL of blood). We achieved 96% trapping of the cancer cells at 600 kHz and 300 V(RMS).

@article{RN209,
   author = {Sano, M. B. and Salmanzadeh, A. and Davalos, R. V.},
   title = {Multilayer contactless dielectrophoresis: theoretical considerations},
   journal = {Electrophoresis},
   volume = {33},
   number = {13},
   pages = {1938-46},
   note = {1522-2683
Sano, Michael B
Salmanzadeh, Alireza
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Germany
2012/07/19
Electrophoresis. 2012 Jul;33(13):1938-46. doi: 10.1002/elps.201100677.},
   abstract = {Dielectrophoresis (DEP), the movement of dielectric particles in a nonuniform electric field, is of particular interest due to its ability to manipulate particles based on their unique electrical properties. Contactless DEP (cDEP) is an extension of traditional and insulator-based DEP topologies. The devices consist of a sample channel and fluid electrode channels filled with a highly conductive media. A thin insulating membrane between the sample channel and the fluid electrode channels serves to isolate the sample from direct contact with metal electrodes. Here we investigate, for the first time, the properties of multilayer devices in which the sample and electrode channels occupy distinct layers. Simulations are conducted using commercially available finite element software and a less computationally demanding numerical approximation is presented and validated. We show that devices can be created that achieve a similar level of electrical performance to other cDEP devices presented in the literature while increasing fluid throughput. We conclude, based on these models, that the ultimate limiting factors in device performance resides in breakdown voltage of the barrier material and the ability to generate high-voltage, high-frequency signals. Finally, we demonstrate trapping of MDA-MB-231 breast cancer cells in a prototype device at a flow rate of 1.0 mL/h when 250 V(RMS) at 600 kHz is applied.},
   keywords = {Cell Line, Tumor
Cell Separation/instrumentation/methods
Computer Simulation
Electric Conductivity
Electrophoresis/*instrumentation/*methods
Humans
*Models, Theoretical
Reproducibility of Results},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201100677},
   year = {2012},
   type = {Journal Article}
}

Dielectrophoresis (DEP), the movement of dielectric particles in a nonuniform electric field, is of particular interest due to its ability to manipulate particles based on their unique electrical properties. Contactless DEP (cDEP) is an extension of traditional and insulator-based DEP topologies. The devices consist of a sample channel and fluid electrode channels filled with a highly conductive media. A thin insulating membrane between the sample channel and the fluid electrode channels serves to isolate the sample from direct contact with metal electrodes. Here we investigate, for the first time, the properties of multilayer devices in which the sample and electrode channels occupy distinct layers. Simulations are conducted using commercially available finite element software and a less computationally demanding numerical approximation is presented and validated. We show that devices can be created that achieve a similar level of electrical performance to other cDEP devices presented in the literature while increasing fluid throughput. We conclude, based on these models, that the ultimate limiting factors in device performance resides in breakdown voltage of the barrier material and the ability to generate high-voltage, high-frequency signals. Finally, we demonstrate trapping of MDA-MB-231 breast cancer cells in a prototype device at a flow rate of 1.0 mL/h when 250 V(RMS) at 600 kHz is applied.

@article{RN208,
   author = {Xiao, S. and Charonko, J. J. and Fu, X. and Salmanzadeh, A. and Davalos, R. V. and Vlachos, P. P. and Finkielstein, C. V. and Capelluto, D. G.},
   title = {Structure, sulfatide binding properties, and inhibition of platelet aggregation by a disabled-2 protein-derived peptide},
   journal = {J Biol Chem},
   volume = {287},
   number = {45},
   pages = {37691-702},
   note = {1083-351x
Xiao, Shuyan
Charonko, John J
Fu, Xiangping
Salmanzadeh, Alireza
Davalos, Rafael V
Vlachos, Pavlos P
Finkielstein, Carla V
Capelluto, Daniel G S
Journal Article
Research Support, Non-U.S. Gov't
United States
2012/09/15
J Biol Chem. 2012 Nov 2;287(45):37691-702. doi: 10.1074/jbc.M112.385609. Epub 2012 Sep 13.},
   abstract = {Disabled-2 (Dab2) targets membranes and triggers a wide range of biological events, including endocytosis and platelet aggregation. Dab2, through its phosphotyrosine-binding (PTB) domain, inhibits platelet aggregation by competing with fibrinogen for α(IIb)β(3) integrin receptor binding. We have recently shown that the N-terminal region, including the PTB domain (N-PTB), drives Dab2 to the platelet membrane surface by binding to sulfatides through two sulfatide-binding motifs, modulating the extent of platelet aggregation. The three-dimensional structure of a Dab2-derived peptide encompassing the sulfatide-binding motifs has been determined in dodecylphosphocholine micelles using NMR spectroscopy. Dab2 sulfatide-binding motif contains two helices when embedded in micelles, reversibly binds to sulfatides with moderate affinity, lies parallel to the micelle surface, and when added to a platelet mixture, reduces the number and size of sulfatide-induced aggregates. Overall, our findings identify and structurally characterize a minimal region in Dab2 that modulates platelet homotypic interactions, all of which provide the foundation for rational design of a new generation of anti-aggregatory low-molecular mass molecules for therapeutic purposes.},
   keywords = {Adaptor Proteins, Signal Transducing/*chemistry/genetics/metabolism
Amino Acid Motifs
Amino Acid Sequence
Apoptosis Regulatory Proteins
Binding Sites
Circular Dichroism
Humans
Micelles
Models, Molecular
Molecular Sequence Data
Peptides/*chemistry/metabolism/*pharmacology
Phosphorylcholine/analogs & derivatives/chemistry
Platelet Adhesiveness/drug effects
Platelet Aggregation/*drug effects
Protein Binding
Protein Structure, Secondary
Protein Structure, Tertiary
Sequence Homology, Amino Acid
Sulfoglycosphingolipids/*chemistry/metabolism
Surface Plasmon Resonance
Tumor Suppressor Proteins/*chemistry/genetics/metabolism},
   ISSN = {0021-9258 (Print)
0021-9258},
   DOI = {10.1074/jbc.M112.385609},
   year = {2012},
   type = {Journal Article}
}

Disabled-2 (Dab2) targets membranes and triggers a wide range of biological events, including endocytosis and platelet aggregation. Dab2, through its phosphotyrosine-binding (PTB) domain, inhibits platelet aggregation by competing with fibrinogen for α(IIb)β(3) integrin receptor binding. We have recently shown that the N-terminal region, including the PTB domain (N-PTB), drives Dab2 to the platelet membrane surface by binding to sulfatides through two sulfatide-binding motifs, modulating the extent of platelet aggregation. The three-dimensional structure of a Dab2-derived peptide encompassing the sulfatide-binding motifs has been determined in dodecylphosphocholine micelles using NMR spectroscopy. Dab2 sulfatide-binding motif contains two helices when embedded in micelles, reversibly binds to sulfatides with moderate affinity, lies parallel to the micelle surface, and when added to a platelet mixture, reduces the number and size of sulfatide-induced aggregates. Overall, our findings identify and structurally characterize a minimal region in Dab2 that modulates platelet homotypic interactions, all of which provide the foundation for rational design of a new generation of anti-aggregatory low-molecular mass molecules for therapeutic purposes.

@article{RN215,
   author = {Arena, C. B. and Sano, M. B. and Rossmeisl, J. H., Jr. and Caldwell, J. L. and Garcia, P. A. and Rylander, M. N. and Davalos, R. V.},
   title = {High-frequency irreversible electroporation (H-FIRE) for non-thermal ablation without muscle contraction},
   journal = {Biomed Eng Online},
   volume = {10},
   pages = {102},
   note = {1475-925x
Arena, Christopher B
Sano, Michael B
Rossmeisl, John H Jr
Caldwell, John L
Garcia, Paulo A
Rylander, Marissa Nichole
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2011/11/23
Biomed Eng Online. 2011 Nov 21;10:102. doi: 10.1186/1475-925X-10-102.},
   abstract = {BACKGROUND: Therapeutic irreversible electroporation (IRE) is an emerging technology for the non-thermal ablation of tumors. The technique involves delivering a series of unipolar electric pulses to permanently destabilize the plasma membrane of cancer cells through an increase in transmembrane potential, which leads to the development of a tissue lesion. Clinically, IRE requires the administration of paralytic agents to prevent muscle contractions during treatment that are associated with the delivery of electric pulses. This study shows that by applying high-frequency, bipolar bursts, muscle contractions can be eliminated during IRE without compromising the non-thermal mechanism of cell death. METHODS: A combination of analytical, numerical, and experimental techniques were performed to investigate high-frequency irreversible electroporation (H-FIRE). A theoretical model for determining transmembrane potential in response to arbitrary electric fields was used to identify optimal burst frequencies and amplitudes for in vivo treatments. A finite element model for predicting thermal damage based on the electric field distribution was used to design non-thermal protocols for in vivo experiments. H-FIRE was applied to the brain of rats, and muscle contractions were quantified via accelerometers placed at the cervicothoracic junction. MRI and histological evaluation was performed post-operatively to assess ablation. RESULTS: No visual or tactile evidence of muscle contraction was seen during H-FIRE at 250 kHz or 500 kHz, while all IRE protocols resulted in detectable muscle contractions at the cervicothoracic junction. H-FIRE produced ablative lesions in brain tissue that were characteristic in cellular morphology of non-thermal IRE treatments. Specifically, there was complete uniformity of tissue death within targeted areas, and a sharp transition zone was present between lesioned and normal brain. CONCLUSIONS: H-FIRE is a feasible technique for non-thermal tissue ablation that eliminates muscle contractions seen in IRE treatments performed with unipolar electric pulses. Therefore, it has the potential to be performed clinically without the administration of paralytic agents.},
   keywords = {Ablation Techniques/*adverse effects
Animals
Brain/physiology
Electroporation/*methods
Finite Element Analysis
Male
Membrane Potentials
*Muscle Contraction
Rats
Temperature},
   ISSN = {1475-925x},
   DOI = {10.1186/1475-925x-10-102},
   year = {2011},
   type = {Journal Article}
}

BACKGROUND: Therapeutic irreversible electroporation (IRE) is an emerging technology for the non-thermal ablation of tumors. The technique involves delivering a series of unipolar electric pulses to permanently destabilize the plasma membrane of cancer cells through an increase in transmembrane potential, which leads to the development of a tissue lesion. Clinically, IRE requires the administration of paralytic agents to prevent muscle contractions during treatment that are associated with the delivery of electric pulses. This study shows that by applying high-frequency, bipolar bursts, muscle contractions can be eliminated during IRE without compromising the non-thermal mechanism of cell death. METHODS: A combination of analytical, numerical, and experimental techniques were performed to investigate high-frequency irreversible electroporation (H-FIRE). A theoretical model for determining transmembrane potential in response to arbitrary electric fields was used to identify optimal burst frequencies and amplitudes for in vivo treatments. A finite element model for predicting thermal damage based on the electric field distribution was used to design non-thermal protocols for in vivo experiments. H-FIRE was applied to the brain of rats, and muscle contractions were quantified via accelerometers placed at the cervicothoracic junction. MRI and histological evaluation was performed post-operatively to assess ablation. RESULTS: No visual or tactile evidence of muscle contraction was seen during H-FIRE at 250 kHz or 500 kHz, while all IRE protocols resulted in detectable muscle contractions at the cervicothoracic junction. H-FIRE produced ablative lesions in brain tissue that were characteristic in cellular morphology of non-thermal IRE treatments. Specifically, there was complete uniformity of tissue death within targeted areas, and a sharp transition zone was present between lesioned and normal brain. CONCLUSIONS: H-FIRE is a feasible technique for non-thermal tissue ablation that eliminates muscle contractions seen in IRE treatments performed with unipolar electric pulses. Therefore, it has the potential to be performed clinically without the administration of paralytic agents.

@article{RN225,
   author = {Arena, C. B. and Sano, M. B. and Rylander, M. N. and Davalos, R. V.},
   title = {Theoretical considerations of tissue electroporation with high-frequency bipolar pulses},
   journal = {IEEE Trans Biomed Eng},
   volume = {58},
   number = {5},
   pages = {1474-82},
   note = {1558-2531
Arena, Christopher B
Sano, Michael B
Rylander, Marissa Nichole
Davalos, Rafael V
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
United States
2010/12/30
IEEE Trans Biomed Eng. 2011 May;58(5):1474-82. doi: 10.1109/TBME.2010.2102021. Epub 2010 Dec 23.},
   abstract = {This study introduces the use of high-frequency pulsed electric fields for tissue electroporation. Through the development of finite element models and the use of analytical techniques, electroporation with rectangular, bipolar pulses is investigated. The electric field and temperature distribution along with the associated transmembrane potential development are considered in a heterogeneous skin fold geometry. Results indicate that switching polarity on the nanosecond scale near the charging time of plasma membranes can greatly improve treatment outcomes in heterogeneous tissues. Specifically, high-frequency fields ranging from 500 kHz to 1 MHz are best suited to penetrate epithelial layers without inducing significant Joule heating, and cause electroporation in underlying cells.},
   keywords = {*Electroporation
Epidermis
Finite Element Analysis
Humans
*Membrane Potentials
*Models, Biological
Skin Physiological Phenomena
Temperature},
   ISSN = {0018-9294},
   DOI = {10.1109/tbme.2010.2102021},
   year = {2011},
   type = {Journal Article}
}

This study introduces the use of high-frequency pulsed electric fields for tissue electroporation. Through the development of finite element models and the use of analytical techniques, electroporation with rectangular, bipolar pulses is investigated. The electric field and temperature distribution along with the associated transmembrane potential development are considered in a heterogeneous skin fold geometry. Results indicate that switching polarity on the nanosecond scale near the charging time of plasma membranes can greatly improve treatment outcomes in heterogeneous tissues. Specifically, high-frequency fields ranging from 500 kHz to 1 MHz are best suited to penetrate epithelial layers without inducing significant Joule heating, and cause electroporation in underlying cells.

@article{RN230,
   author = {Ellis, T. L. and Garcia, P. A. and Rossmeisl, J. H., Jr. and Henao-Guerrero, N. and Robertson, J. and Davalos, R. V.},
   title = {Nonthermal irreversible electroporation for intracranial surgical applications. Laboratory investigation},
   journal = {J Neurosurg},
   volume = {114},
   number = {3},
   pages = {681-8},
   note = {1933-0693
Ellis, Thomas L
Garcia, Paulo A
Rossmeisl, John H Jr
Henao-Guerrero, Natalia
Robertson, John
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2010/06/22
J Neurosurg. 2011 Mar;114(3):681-8. doi: 10.3171/2010.5.JNS091448. Epub 2010 Jun 18.},
   abstract = {OBJECT: Nonthermal irreversible electroporation (NTIRE) is a novel, minimally invasive technique to treat cancer, which is unique because of its nonthermal mechanism of tumor ablation. This paper evaluates the safety of an NTIRE procedure to lesion normal canine brain tissue. METHODS: The NTIRE procedure involved placing electrodes into a targeted area of brain in 3 dogs and delivering a series of short and intense electric pulses. The voltages of the pulses applied were varied between dogs. Another dog was used as a sham control. One additional dog was treated at an extreme voltage to determine the upper safety limits of the procedure. Ultrasonography was used at the time of the procedure to determine if the lesions could be visualized intraoperatively. The volumes of ablated tissue were then estimated on postprocedure MR imaging. Histological brain sections were then analyzed to evaluate the lesions produced. RESULTS: The animals tolerated the procedure with no apparent complications except for the animal that was treated at the upper voltage limit. The lesion volume appeared to decrease with decreasing voltage of applied pulses. Histological examination revealed cell death within the treated volume with a submillimeter transition zone between necrotic and normal brain. CONCLUSIONS: The authors' results reveal that NTIRE at selected voltages can be safely administered in normal canine brain and that the volume of ablated tissue correlates with the voltage of the applied pulses. This preliminary study is the first step toward using NTIRE as a brain cancer treatment.},
   keywords = {Algorithms
Animals
Brain/*surgery
Brain Neoplasms
Cell Death
Cell Membrane/physiology/ultrastructure
Dogs
Electric Stimulation
Electrodes, Implanted
Electroporation/*methods
Magnetic Resonance Imaging
Necrosis
Neurosurgical Procedures/adverse effects/*methods
Pilot Projects},
   ISSN = {0022-3085},
   DOI = {10.3171/2010.5.Jns091448},
   year = {2011},
   type = {Journal Article}
}

OBJECT: Nonthermal irreversible electroporation (NTIRE) is a novel, minimally invasive technique to treat cancer, which is unique because of its nonthermal mechanism of tumor ablation. This paper evaluates the safety of an NTIRE procedure to lesion normal canine brain tissue. METHODS: The NTIRE procedure involved placing electrodes into a targeted area of brain in 3 dogs and delivering a series of short and intense electric pulses. The voltages of the pulses applied were varied between dogs. Another dog was used as a sham control. One additional dog was treated at an extreme voltage to determine the upper safety limits of the procedure. Ultrasonography was used at the time of the procedure to determine if the lesions could be visualized intraoperatively. The volumes of ablated tissue were then estimated on postprocedure MR imaging. Histological brain sections were then analyzed to evaluate the lesions produced. RESULTS: The animals tolerated the procedure with no apparent complications except for the animal that was treated at the upper voltage limit. The lesion volume appeared to decrease with decreasing voltage of applied pulses. Histological examination revealed cell death within the treated volume with a submillimeter transition zone between necrotic and normal brain. CONCLUSIONS: The authors' results reveal that NTIRE at selected voltages can be safely administered in normal canine brain and that the volume of ablated tissue correlates with the voltage of the applied pulses. This preliminary study is the first step toward using NTIRE as a brain cancer treatment.

@article{RN221,
   author = {Gallo-Villanueva, R. C. and Pérez-González, V. H. and Davalos, R. V. and Lapizco-Encinas, B. H.},
   title = {Separation of mixtures of particles in a multipart microdevice employing insulator-based dielectrophoresis},
   journal = {Electrophoresis},
   volume = {32},
   number = {18},
   pages = {2456-65},
   note = {1522-2683
Gallo-Villanueva, Roberto C
Pérez-González, Victor H
Davalos, Rafael V
Lapizco-Encinas, Blanca H
Journal Article
Research Support, Non-U.S. Gov't
Germany
2011/08/30
Electrophoresis. 2011 Sep;32(18):2456-65. doi: 10.1002/elps.201100174. Epub 2011 Aug 23.},
   abstract = {Dielectrophoresis is the electrokinetic movement of particles due to polarization effects in the presence of non-uniform electric fields. In insulator-based dielectrophoresis (iDEP) regions of low and high electric field intensity, i.e. non-uniformity of electric field, are produced when the cross-sectional area of a microchannel is decreased by the presence of electrical insulating structures between two electrodes. This technique is increasingly being studied for the manipulation of a wide variety of particles, and novel designs are continuously developed. Despite significant advances in the area, complex mixture separation and sample fractionation continue to be the most important challenges. In this work, a microchannel design is presented for carrying out direct current (DC)-iDEP for the separation of a mixture of particles. The device comprises a main channel, two side channels and two sections of cylindrical posts with different diameters, which will generate different non-uniformities in the electric field on the main channel, designed for the discrimination and separation of particles of two different sizes. By applying an electric potential of 1000 V, a mixture of 1 and 4 μm polystyrene microspheres were dielectrophoretically separated and concentrated at the same time and then redirected to different outlets. The results obtained here demonstrate that, by carefully designing the device geometry and selecting operating conditions, effective sorting of particle mixtures can be achieved in this type of multi-section DC-iDEP devices.},
   keywords = {Computer Simulation
Electric Conductivity
Electrophoresis/*methods
Microfluidic Analytical Techniques/*instrumentation/*methods
Microspheres
*Models, Chemical
Particle Size
Polystyrenes/chemistry},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201100174},
   year = {2011},
   type = {Journal Article}
}

Dielectrophoresis is the electrokinetic movement of particles due to polarization effects in the presence of non-uniform electric fields. In insulator-based dielectrophoresis (iDEP) regions of low and high electric field intensity, i.e. non-uniformity of electric field, are produced when the cross-sectional area of a microchannel is decreased by the presence of electrical insulating structures between two electrodes. This technique is increasingly being studied for the manipulation of a wide variety of particles, and novel designs are continuously developed. Despite significant advances in the area, complex mixture separation and sample fractionation continue to be the most important challenges. In this work, a microchannel design is presented for carrying out direct current (DC)-iDEP for the separation of a mixture of particles. The device comprises a main channel, two side channels and two sections of cylindrical posts with different diameters, which will generate different non-uniformities in the electric field on the main channel, designed for the discrimination and separation of particles of two different sizes. By applying an electric potential of 1000 V, a mixture of 1 and 4 μm polystyrene microspheres were dielectrophoretically separated and concentrated at the same time and then redirected to different outlets. The results obtained here demonstrate that, by carefully designing the device geometry and selecting operating conditions, effective sorting of particle mixtures can be achieved in this type of multi-section DC-iDEP devices.

@article{RN213,
   author = {Garcia, P. A. and Rossmeisl, J. H., Jr. and Davalos, R. V.},
   title = {Electrical conductivity changes during irreversible electroporation treatment of brain cancer},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2011},
   pages = {739-42},
   note = {2694-0604
Garcia, Paulo A
Rossmeisl, John H Jr
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2012/01/19
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:739-42. doi: 10.1109/IEMBS.2011.6090168.},
   abstract = {Irreversible electroporation (IRE) is a new minimally invasive technique to kill tumors and other undesirable tissue in a non-thermal manner. During an IRE treatment, a series of short and intense electric pulses are delivered to the region of interest to destabilize the cell membranes in the tissue and achieve spontaneous cell death. The alteration of the cellular membrane results in a dramatic increase in electrical conductivity during IRE as in other electroporation-based-therapies. In this study, we performed the planning and execution of an IRE brain cancer treatment using MRI reconstructions of the tumor and a multichannel array that served as a stereotactic fiducial and electrode guide. Using the tumor reconstructions within our numerical simulations, we developed equations relating the increase in tumor conductivity to calculated currents and volumes of tumor treated with IRE. We also correlated the experimental current measured during the procedure to an increase in tumor conductivity ranging between 3.42-3.67 times the baseline conductivity, confirming the physical phenomenon that has been detected in other tissues undergoing similar electroporation-based treatments.},
   keywords = {Antineoplastic Agents/*administration & dosage
Brain Neoplasms/*drug therapy/*physiopathology
Computer Simulation
Electric Conductivity
Electroporation/*methods
Humans
*Models, Biological
Therapy, Computer-Assisted/*methods},
   ISSN = {2375-7477},
   DOI = {10.1109/iembs.2011.6090168},
   year = {2011},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a new minimally invasive technique to kill tumors and other undesirable tissue in a non-thermal manner. During an IRE treatment, a series of short and intense electric pulses are delivered to the region of interest to destabilize the cell membranes in the tissue and achieve spontaneous cell death. The alteration of the cellular membrane results in a dramatic increase in electrical conductivity during IRE as in other electroporation-based-therapies. In this study, we performed the planning and execution of an IRE brain cancer treatment using MRI reconstructions of the tumor and a multichannel array that served as a stereotactic fiducial and electrode guide. Using the tumor reconstructions within our numerical simulations, we developed equations relating the increase in tumor conductivity to calculated currents and volumes of tumor treated with IRE. We also correlated the experimental current measured during the procedure to an increase in tumor conductivity ranging between 3.42-3.67 times the baseline conductivity, confirming the physical phenomenon that has been detected in other tissues undergoing similar electroporation-based treatments.

@article{RN223,
   author = {Garcia, P. A. and Rossmeisl, J. H., Jr. and Neal, R. E., 2nd and Ellis, T. L. and Davalos, R. V.},
   title = {A parametric study delineating irreversible electroporation from thermal damage based on a minimally invasive intracranial procedure},
   journal = {Biomed Eng Online},
   volume = {10},
   pages = {34},
   note = {1475-925x
Garcia, Paulo A
Rossmeisl, John H Jr
Neal, Robert E 2nd
Ellis, Thomas L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2011/05/03
Biomed Eng Online. 2011 Apr 30;10:34. doi: 10.1186/1475-925X-10-34.},
   abstract = {BACKGROUND: Irreversible electroporation (IRE) is a new minimally invasive technique to kill undesirable tissue in a non-thermal manner. In order to maximize the benefits from an IRE procedure, the pulse parameters and electrode configuration must be optimized to achieve complete coverage of the targeted tissue while preventing thermal damage due to excessive Joule heating. METHODS: We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure. These models were adapted to assess the effects of temperature, electroporation, pulse duration, and repetition rate on the volumes of tissue undergoing IRE alone or in superposition with thermal damage. RESULTS: Nine different combinations of voltage and pulse frequency were investigated, five of which resulted in IRE alone while four produced IRE in superposition with thermal damage. CONCLUSIONS: The parametric study evaluated the influence of pulse frequency and applied voltage on treatment volumes, and refined a proposed method to delineate IRE from thermal damage. We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment. The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation.},
   keywords = {Animals
Brain/*cytology
Dogs
Electric Conductivity
*Electroporation
Hot Temperature/*adverse effects
*Models, Biological
Time Factors},
   ISSN = {1475-925x},
   DOI = {10.1186/1475-925x-10-34},
   year = {2011},
   type = {Journal Article}
}

BACKGROUND: Irreversible electroporation (IRE) is a new minimally invasive technique to kill undesirable tissue in a non-thermal manner. In order to maximize the benefits from an IRE procedure, the pulse parameters and electrode configuration must be optimized to achieve complete coverage of the targeted tissue while preventing thermal damage due to excessive Joule heating. METHODS: We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure. These models were adapted to assess the effects of temperature, electroporation, pulse duration, and repetition rate on the volumes of tissue undergoing IRE alone or in superposition with thermal damage. RESULTS: Nine different combinations of voltage and pulse frequency were investigated, five of which resulted in IRE alone while four produced IRE in superposition with thermal damage. CONCLUSIONS: The parametric study evaluated the influence of pulse frequency and applied voltage on treatment volumes, and refined a proposed method to delineate IRE from thermal damage. We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment. The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation.

@article{RN220,
   author = {Henslee, E. A. and Sano, M. B. and Rojas, A. D. and Schmelz, E. M. and Davalos, R. V.},
   title = {Selective concentration of human cancer cells using contactless dielectrophoresis},
   journal = {Electrophoresis},
   volume = {32},
   number = {18},
   pages = {2523-9},
   note = {1522-2683
Henslee, Erin A
Sano, Michael B
Rojas, Andrea D
Schmelz, Eva M
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Germany
2011/09/17
Electrophoresis. 2011 Sep;32(18):2523-9. doi: 10.1002/elps.201100081. Epub 2011 Aug 26.},
   abstract = {This work is the first to demonstrate the ability of contactless dielectrophoresis (cDEP) to isolate target cell species from a heterogeneous sample of live cells. Since all cell types have a unique molecular composition, it is expected that their dielectrophoretic (DEP) properties are also unique. cDEP is a technique developed to improve upon traditional and insulator-based DEP devices by replacing embedded metal electrodes with fluid electrode channels positioned alongside desired trapping locations. Through the placement of the fluid electrode channels and the removal of contact between the electrodes and the sample fluid, cDEP mitigates issues associated with sample/electrode contact. MCF10A, MCF7, and MDA-MB-231 human breast cells were used to represent early, intermediate, and late-staged breast cancer, respectively. Trapping frequency responses of each cell type were distinct, with the largest difference between the cells found at 20 and 30 V. MDA-MB-231 cells were successfully isolated from a population containing MCF10A and MCF7 cells at 30 V and 164 kHz. The ability to selectively concentrate cells is the key to development of biological applications using DEP. The isolation of these cells could provide a workbench for clinicians to detect transformed cells at their earliest stage, screen drug therapies prior to patient treatment, increasing the probability of success, and eliminate unsuccessful treatment options.},
   keywords = {Cell Line, Tumor
Cell Separation/instrumentation/*methods
Electrodes
Electrophoresis/instrumentation/*methods
Humans
Microfluidic Analytical Techniques/instrumentation/*methods
Neoplasms/chemistry/*pathology},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201100081},
   year = {2011},
   type = {Journal Article}
}

This work is the first to demonstrate the ability of contactless dielectrophoresis (cDEP) to isolate target cell species from a heterogeneous sample of live cells. Since all cell types have a unique molecular composition, it is expected that their dielectrophoretic (DEP) properties are also unique. cDEP is a technique developed to improve upon traditional and insulator-based DEP devices by replacing embedded metal electrodes with fluid electrode channels positioned alongside desired trapping locations. Through the placement of the fluid electrode channels and the removal of contact between the electrodes and the sample fluid, cDEP mitigates issues associated with sample/electrode contact. MCF10A, MCF7, and MDA-MB-231 human breast cells were used to represent early, intermediate, and late-staged breast cancer, respectively. Trapping frequency responses of each cell type were distinct, with the largest difference between the cells found at 20 and 30 V. MDA-MB-231 cells were successfully isolated from a population containing MCF10A and MCF7 cells at 30 V and 164 kHz. The ability to selectively concentrate cells is the key to development of biological applications using DEP. The isolation of these cells could provide a workbench for clinicians to detect transformed cells at their earliest stage, screen drug therapies prior to patient treatment, increasing the probability of success, and eliminate unsuccessful treatment options.

@article{RN212,
   author = {Neal, R. E., 2nd and Garcia, P. A. and Robertson, J. L. and Davalos, R. V.},
   title = {Experimental characterization of intrapulse tissue conductivity changes for electroporation},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2011},
   pages = {5581-4},
   note = {2694-0604
Neal, Robert E 2nd
Garcia, Paulo A
Robertson, John L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2012/01/19
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:5581-4. doi: 10.1109/IEMBS.2011.6091350.},
   abstract = {Cells exposed to short electric pulses experience a change in their transmembrane potential, which can lead to increased membrane permeability of the cell. When the energy of the pulses surpasses a threshold, the cell dies in a non-thermal manner known as irreversible electroporation (IRE). IRE has shown promise in the focal ablation of pathologic tissues. Its non-thermal mechanism spares sensitive structures and facilitates rapid lesion resolution. IRE effects depend on the electric field distribution, which can be predicted with numerical modeling. When the cells become permeabilized, the bulk tissue properties change, affecting this distribution. For IRE to become a reliable and successful treatment of diseased tissues, robust predictive treatment planning methods must be developed. It is vital to understand the changes in tissue properties undergoing the electric pulses to improve numerical models and predict treatment volumes. We report on the experimental characterization of these changes for kidney tissue. Tissue samples were pulsed between plate electrodes while intrapulse voltage and current data were measured to determine the conductivity of the tissue during the pulse. Conductivity was then established as a function of the electric field to which the tissue is exposed. This conductivity curve was used in a numerical model to demonstrate the impact of accounting for these changes when modeling electric field distributions to develop treatment plans.},
   keywords = {Animals
Computer Simulation
Dose-Response Relationship, Radiation
Electric Conductivity
Electromagnetic Fields
Electroporation/*methods
In Vitro Techniques
Kidney Medulla/*physiology/*radiation effects
*Models, Biological
Radiation Dosage
Swine},
   ISSN = {2375-7477},
   DOI = {10.1109/iembs.2011.6091350},
   year = {2011},
   type = {Journal Article}
}

Cells exposed to short electric pulses experience a change in their transmembrane potential, which can lead to increased membrane permeability of the cell. When the energy of the pulses surpasses a threshold, the cell dies in a non-thermal manner known as irreversible electroporation (IRE). IRE has shown promise in the focal ablation of pathologic tissues. Its non-thermal mechanism spares sensitive structures and facilitates rapid lesion resolution. IRE effects depend on the electric field distribution, which can be predicted with numerical modeling. When the cells become permeabilized, the bulk tissue properties change, affecting this distribution. For IRE to become a reliable and successful treatment of diseased tissues, robust predictive treatment planning methods must be developed. It is vital to understand the changes in tissue properties undergoing the electric pulses to improve numerical models and predict treatment volumes. We report on the experimental characterization of these changes for kidney tissue. Tissue samples were pulsed between plate electrodes while intrapulse voltage and current data were measured to determine the conductivity of the tissue during the pulse. Conductivity was then established as a function of the electric field to which the tissue is exposed. This conductivity curve was used in a numerical model to demonstrate the impact of accounting for these changes when modeling electric field distributions to develop treatment plans.

@article{RN224,
   author = {Neal, R. E., 2nd and Rossmeisl, J. H., Jr. and Garcia, P. A. and Lanz, O. I. and Henao-Guerrero, N. and Davalos, R. V.},
   title = {Successful treatment of a large soft tissue sarcoma with irreversible electroporation},
   journal = {J Clin Oncol},
   volume = {29},
   number = {13},
   pages = {e372-7},
   note = {1527-7755
Neal, Robert E 2nd
Rossmeisl, John H Jr
Garcia, Paulo A
Lanz, Otto I
Henao-Guerrero, Natalia
Davalos, Rafael V
Case Reports
Journal Article
Research Support, Non-U.S. Gov't
United States
2011/02/16
J Clin Oncol. 2011 May 1;29(13):e372-7. doi: 10.1200/JCO.2010.33.0902. Epub 2011 Feb 14.},
   keywords = {Animals
Dog Diseases/*therapy
Dogs
Electroporation/methods/*veterinary
Female
Histiocytic Sarcoma/therapy/*veterinary
Sarcoma/*therapy/*veterinary
*Thigh
Treatment Outcome},
   ISSN = {0732-183x},
   DOI = {10.1200/jco.2010.33.0902},
   year = {2011},
   type = {Journal Article}
}

@article{RN219,
   author = {Salmanzadeh, A. and Shafiee, H. and Davalos, R. V. and Stremler, M. A.},
   title = {Microfluidic mixing using contactless dielectrophoresis},
   journal = {Electrophoresis},
   volume = {32},
   number = {18},
   pages = {2569-78},
   note = {1522-2683
Salmanzadeh, Alireza
Shafiee, Hadi
Davalos, Rafael V
Stremler, Mark A
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Germany
2011/09/17
Electrophoresis. 2011 Sep;32(18):2569-78. doi: 10.1002/elps.201100171. Epub 2011 Aug 26.},
   abstract = {The first experimental evidence of mixing enhancement in a microfluidic system using contactless dielectrophoresis (cDEP) is presented in this work. Pressure-driven flow of deionized water containing 0.5 μm beads was mixed in various chamber geometries by imposing a dielectrophoresis (DEP) force on the beads. In cDEP the electrodes are not in direct contact with the fluid sample but are instead capacitively coupled to the mixing chamber through thin dielectric barriers, which eliminates many of the problems encountered with standard DEP. Four system designs with rectangular and circular mixing chambers were fabricated in PDMS. Mixing tests were conducted for flow rates from 0.005 to 1 mL/h subject to an alternating current signal range of 0-300 V at 100-600 kHz. When the time scales of the bulk fluid motion and the DEP motion were commensurate, rapid mixing was observed. The rectangular mixing chambers were found to be more efficient than the circular chambers. This approach shows potential for mixing low diffusivity biological samples, which is a very challenging problem in laminar flows at small scales.},
   keywords = {Electrophoresis/*methods
Equipment Design
Microfluidic Analytical Techniques/*instrumentation/*methods
Microspheres
Models, Chemical
Polystyrenes/chemistry
Water/chemistry},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201100171},
   year = {2011},
   type = {Journal Article}
}

The first experimental evidence of mixing enhancement in a microfluidic system using contactless dielectrophoresis (cDEP) is presented in this work. Pressure-driven flow of deionized water containing 0.5 μm beads was mixed in various chamber geometries by imposing a dielectrophoresis (DEP) force on the beads. In cDEP the electrodes are not in direct contact with the fluid sample but are instead capacitively coupled to the mixing chamber through thin dielectric barriers, which eliminates many of the problems encountered with standard DEP. Four system designs with rectangular and circular mixing chambers were fabricated in PDMS. Mixing tests were conducted for flow rates from 0.005 to 1 mL/h subject to an alternating current signal range of 0-300 V at 100-600 kHz. When the time scales of the bulk fluid motion and the DEP motion were commensurate, rapid mixing was observed. The rectangular mixing chambers were found to be more efficient than the circular chambers. This approach shows potential for mixing low diffusivity biological samples, which is a very challenging problem in laminar flows at small scales.

@article{RN211,
   author = {Sano, M. B. and Caldwell, J. L. and Davalos, R. V.},
   title = {A low cost solution for the fabrication of dielectrophoretic microfluidic devices and embedded electrodes},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2011},
   pages = {8384-7},
   note = {2694-0604
Sano, Michael B
Caldwell, John L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2012/01/19
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:8384-7. doi: 10.1109/IEMBS.2011.6092068.},
   abstract = {The versatility of a simple method for producing microfluidic devices with embedded electrodes is demonstrated through the fabrication and operation of two dielectrophoretic devices; one employing interdigitated electrode structures on glass and the other employing contactless electrode reservoirs. Device manufacture is based on the precipitation of silver and subsequent photolithography of thin film resists conducted outside of a cleanroom environment. In current experiments, minimum channel widths of 50 microns and electrode widths of 25 microns are achieved when the distance between features is 40 microns or greater. These results illustrate this technique's potential to produce microfluidic devices with embedded electrodes for lab on chip applications while significantly reducing fabrication expense.},
   keywords = {Dimethylpolysiloxanes/chemistry
Electric Power Supplies
Electrodes
Electrophoresis, Microchip/*economics/*instrumentation
Ultraviolet Rays},
   ISSN = {2375-7477},
   DOI = {10.1109/iembs.2011.6092068},
   year = {2011},
   type = {Journal Article}
}

The versatility of a simple method for producing microfluidic devices with embedded electrodes is demonstrated through the fabrication and operation of two dielectrophoretic devices; one employing interdigitated electrode structures on glass and the other employing contactless electrode reservoirs. Device manufacture is based on the precipitation of silver and subsequent photolithography of thin film resists conducted outside of a cleanroom environment. In current experiments, minimum channel widths of 50 microns and electrode widths of 25 microns are achieved when the distance between features is 40 microns or greater. These results illustrate this technique's potential to produce microfluidic devices with embedded electrodes for lab on chip applications while significantly reducing fabrication expense.

@article{RN218,
   author = {Sano, M. B. and Caldwell, J. L. and Davalos, R. V.},
   title = {Modeling and development of a low frequency contactless dielectrophoresis (cDEP) platform to sort cancer cells from dilute whole blood samples},
   journal = {Biosens Bioelectron},
   volume = {30},
   number = {1},
   pages = {13-20},
   note = {1873-4235
Sano, Michael B
Caldwell, John L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
England
2011/09/29
Biosens Bioelectron. 2011 Dec 15;30(1):13-20. doi: 10.1016/j.bios.2011.07.048. Epub 2011 Aug 9.},
   abstract = {Contactless dielectrophoresis (cDEP) devices are a new adaptation of dielectrophoresis in which fluid electrodes, isolated from the main microfluidic channel by a thin membrane, provide the electric field gradients necessary to manipulate cells. This work presents a continuous sorting device which is the first cDEP design capable of exploiting the Clausius-Mossotti factor at frequencies where it is both positive and negative for mammalian cells. Experimental devices are fabricated using a cost effective technique which can achieve 50 μm feature sizes and does not require the use of a cleanroom or specialized equipment. An analytical model is developed to evaluate cDEP devices as a network of parallel resistor-capacitor pairs. Two theoretical devices are presented and evaluated using finite element methods to demonstrate the effect of geometry on the development of electric field gradients across a wide frequency spectrum. Finally, we present an experimental device capable of continuously sorting human leukemia cells from dilute blood samples. This is the first cDEP device designed to operate below 100 kHz resulting in successful manipulation of human leukemia cells, while in the background red blood cells are unaffected.},
   keywords = {Biosensing Techniques/*instrumentation
Blood Component Removal/*instrumentation
Cell Separation/*instrumentation
Computer Simulation
Computer-Aided Design
Conductometry/*instrumentation
Electrophoresis/*instrumentation
Equipment Design
Equipment Failure Analysis
Microfluidic Analytical Techniques/*instrumentation
Models, Theoretical
Neoplasms/*pathology},
   ISSN = {0956-5663},
   DOI = {10.1016/j.bios.2011.07.048},
   year = {2011},
   type = {Journal Article}
}

Contactless dielectrophoresis (cDEP) devices are a new adaptation of dielectrophoresis in which fluid electrodes, isolated from the main microfluidic channel by a thin membrane, provide the electric field gradients necessary to manipulate cells. This work presents a continuous sorting device which is the first cDEP design capable of exploiting the Clausius-Mossotti factor at frequencies where it is both positive and negative for mammalian cells. Experimental devices are fabricated using a cost effective technique which can achieve 50 μm feature sizes and does not require the use of a cleanroom or specialized equipment. An analytical model is developed to evaluate cDEP devices as a network of parallel resistor-capacitor pairs. Two theoretical devices are presented and evaluated using finite element methods to demonstrate the effect of geometry on the development of electric field gradients across a wide frequency spectrum. Finally, we present an experimental device capable of continuously sorting human leukemia cells from dilute blood samples. This is the first cDEP device designed to operate below 100 kHz resulting in successful manipulation of human leukemia cells, while in the background red blood cells are unaffected.

@article{RN216,
   author = {Sano, M. B. and Henslee, E. A. and Schmelz, E. and Davalos, R. V.},
   title = {Contactless dielectrophoretic spectroscopy: examination of the dielectric properties of cells found in blood},
   journal = {Electrophoresis},
   volume = {32},
   number = {22},
   pages = {3164-71},
   note = {1522-2683
Sano, Michael B
Henslee, Erin A
Schmelz, Eva
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Germany
2011/11/22
Electrophoresis. 2011 Nov;32(22):3164-71. doi: 10.1002/elps.201100351.},
   abstract = {The use of non-invasive methods to detect and enrich circulating tumor cells (CTCs) independent of their genotype is critical for early diagnostic and treatment purposes. The key to using CTCs as predictive clinical biomarkers is their separation and enrichment. This work presents the use of a contactless dielectrophoresis (cDEP) device to investigate the frequency response of cells and calculate their area-specific membrane capacitance. This is the first demonstration of a cDEP device which is capable of operating between 10 and 100  kHz. Positive and negative dielectrophoretic responses were observed in red blood cells, macrophages, breast cancer, and leukemia cells. The area-specific membrane capacitances of MDA-MB231, THP-1 and PC1 cells were determined to be 0.01518 ± 0.0013, 0.01719 ± 0.0020, 0.01275 ± 0.0018 (F/m(2)), respectively. By first establishing the dielectrophoretic responses of cancerous cells within this cDEP device, conditions to detect and enrich tumor cells from mixtures with non-transformed cells can be determined providing further information to develop methods to isolate these rare cells.},
   keywords = {Cell Line, Tumor
Cell Separation/*instrumentation/methods
Computer Simulation
Electrophoresis/*instrumentation
Humans
Neoplastic Cells, Circulating/*chemistry
Spectrum Analysis/*instrumentation},
   ISSN = {0173-0835},
   DOI = {10.1002/elps.201100351},
   year = {2011},
   type = {Journal Article}
}

The use of non-invasive methods to detect and enrich circulating tumor cells (CTCs) independent of their genotype is critical for early diagnostic and treatment purposes. The key to using CTCs as predictive clinical biomarkers is their separation and enrichment. This work presents the use of a contactless dielectrophoresis (cDEP) device to investigate the frequency response of cells and calculate their area-specific membrane capacitance. This is the first demonstration of a cDEP device which is capable of operating between 10 and 100  kHz. Positive and negative dielectrophoretic responses were observed in red blood cells, macrophages, breast cancer, and leukemia cells. The area-specific membrane capacitances of MDA-MB231, THP-1 and PC1 cells were determined to be 0.01518 ± 0.0013, 0.01719 ± 0.0020, 0.01275 ± 0.0018 (F/m(2)), respectively. By first establishing the dielectrophoretic responses of cancerous cells within this cDEP device, conditions to detect and enrich tumor cells from mixtures with non-transformed cells can be determined providing further information to develop methods to isolate these rare cells.

@article{RN222,
   author = {Welsh, J. D. and Charonko, J. J. and Salmanzadeh, A. and Drahos, K. E. and Shafiee, H. and Stremler, M. A. and Davalos, R. V. and Capelluto, D. G. and Vlachos, P. P. and Finkielstein, C. V.},
   title = {Disabled-2 modulates homotypic and heterotypic platelet interactions by binding to sulfatides},
   journal = {Br J Haematol},
   volume = {154},
   number = {1},
   pages = {122-33},
   note = {1365-2141
Welsh, John D
Charonko, John J
Salmanzadeh, Alireza
Drahos, Karen E
Shafiee, Hadi
Stremler, Mark A
Davalos, Rafael V
Capelluto, Daniel G S
Vlachos, Pavlos P
Finkielstein, Carla V
Journal Article
England
2011/05/05
Br J Haematol. 2011 Jul;154(1):122-33. doi: 10.1111/j.1365-2141.2011.08705.x. Epub 2011 May 3.},
   abstract = {Disabled-2 (Dab2) inhibits platelet aggregation by competing with fibrinogen for binding to the α(IIb) β(3) integrin receptor, an interaction that is modulated by Dab2 binding to sulfatides at the outer leaflet of the platelet plasma membrane. The disaggregatory function of Dab2 has been mapped to its N-terminus phosphotyrosine-binding (N-PTB) domain. Our data show that the surface levels of P-selectin, a platelet transmembrane protein known to bind sulfatides and promote cell-cell interactions, are reduced by Dab2 N-PTB, an event that is reversed in the presence of a mutant form of the protein that is deficient in sulfatide but not in integrin binding. Importantly, Dab2 N-PTB, but not its sulfatide binding-deficient form, was able to prevent sulfatide-induced platelet aggregation when tested under haemodynamic conditions in microfluidic devices at flow rates with shear stress levels corresponding to those found in vein microcirculation. Moreover, the regulatory role of Dab2 N-PTB extends to platelet-leucocyte adhesion and aggregation events, suggesting a multi-target role for Dab2 in haemostasis.},
   keywords = {Adaptor Proteins, Signal Transducing/metabolism/*pharmacology
Apoptosis Regulatory Proteins
Cell Communication/drug effects/physiology
Hemorheology
Humans
Leukocytes/physiology
Microfluidic Analytical Techniques
P-Selectin/metabolism
Platelet Activation/physiology
Platelet Adhesiveness/drug effects/physiology
Platelet Aggregation/*drug effects/physiology
Sulfoglycosphingolipids/*metabolism
Tumor Suppressor Proteins},
   ISSN = {0007-1048},
   DOI = {10.1111/j.1365-2141.2011.08705.x},
   year = {2011},
   type = {Journal Article}
}

Disabled-2 (Dab2) inhibits platelet aggregation by competing with fibrinogen for binding to the α(IIb) β(3) integrin receptor, an interaction that is modulated by Dab2 binding to sulfatides at the outer leaflet of the platelet plasma membrane. The disaggregatory function of Dab2 has been mapped to its N-terminus phosphotyrosine-binding (N-PTB) domain. Our data show that the surface levels of P-selectin, a platelet transmembrane protein known to bind sulfatides and promote cell-cell interactions, are reduced by Dab2 N-PTB, an event that is reversed in the presence of a mutant form of the protein that is deficient in sulfatide but not in integrin binding. Importantly, Dab2 N-PTB, but not its sulfatide binding-deficient form, was able to prevent sulfatide-induced platelet aggregation when tested under haemodynamic conditions in microfluidic devices at flow rates with shear stress levels corresponding to those found in vein microcirculation. Moreover, the regulatory role of Dab2 N-PTB extends to platelet-leucocyte adhesion and aggregation events, suggesting a multi-target role for Dab2 in haemostasis.

@article{RN228,
   author = {Garcia, P. A. and Neal, R. E. and Rossmeisl, J. H. and Davalos, R. V.},
   title = {Non-thermal irreversible electroporation for deep intracranial disorders},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2010},
   pages = {2743-6},
   note = {Garcia, Paulo A
Neal, Robert E
Rossmeisl, John H
Davalos, Rafael V
Journal Article
United States
2010/11/26
Annu Int Conf IEEE Eng Med Biol Soc. 2010;2010:2743-6. doi: 10.1109/IEMBS.2010.5626371.},
   abstract = {Non-thermal irreversible electroporation (N-TIRE) is a new minimally invasive technique to kill undesirable tissue. We build on our previous intracranial studies in order to evaluate the possibility of using N-TIRE for deep intracranial disorders. In this manuscript we describe a minimally invasive computed tomography (CT) guided N-TIRE procedure in white matter. In addition, we report the electric field threshold needed for white matter ablation (630 - 875 V/cm) using four sets of twenty 50 µs pulses at a voltage-to-distance ratio of 1000 V/cm. We also confirm the non-thermal aspect of the technique with real time temperature data measured at the electrode-tissue interface.},
   keywords = {Algorithms
Animals
Body Temperature
Brain/pathology
Brain Neoplasms/*therapy/veterinary
Catheter Ablation/*methods
Computers
Corpus Callosum/pathology
Dogs
Electrodes
Electroporation/*methods
Medical Oncology/methods
Models, Theoretical
Temperature
Tomography, X-Ray Computed/methods},
   ISSN = {2375-7477 (Print)
2375-7477},
   DOI = {10.1109/iembs.2010.5626371},
   year = {2010},
   type = {Journal Article}
}

Non-thermal irreversible electroporation (N-TIRE) is a new minimally invasive technique to kill undesirable tissue. We build on our previous intracranial studies in order to evaluate the possibility of using N-TIRE for deep intracranial disorders. In this manuscript we describe a minimally invasive computed tomography (CT) guided N-TIRE procedure in white matter. In addition, we report the electric field threshold needed for white matter ablation (630 - 875 V/cm) using four sets of twenty 50 µs pulses at a voltage-to-distance ratio of 1000 V/cm. We also confirm the non-thermal aspect of the technique with real time temperature data measured at the electrode-tissue interface.

@article{RN229,
   author = {Garcia, P. A. and Rossmeisl, J. H., Jr. and Neal, R. E., 2nd and Ellis, T. L. and Olson, J. D. and Henao-Guerrero, N. and Robertson, J. and Davalos, R. V.},
   title = {Intracranial nonthermal irreversible electroporation: in vivo analysis},
   journal = {J Membr Biol},
   volume = {236},
   number = {1},
   pages = {127-36},
   note = {1432-1424
Garcia, Paulo A
Rossmeisl, John H Jr
Neal, Robert E 2nd
Ellis, Thomas L
Olson, John D
Henao-Guerrero, Natalia
Robertson, John
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
United States
2010/07/30
J Membr Biol. 2010 Jul;236(1):127-36. doi: 10.1007/s00232-010-9284-z. Epub 2010 Jul 29.},
   abstract = {Nonthermal irreversible electroporation (NTIRE) is a new minimally invasive technique to treat cancer. It is unique because of its nonthermal mechanism of tumor ablation. Intracranial NTIRE procedures involve placing electrodes into the targeted area of the brain and delivering a series of short but intense electric pulses. The electric pulses induce irreversible structural changes in cell membranes, leading to cell death. We correlated NTIRE lesion volumes in normal brain tissue with electric field distributions from comprehensive numerical models. The electrical conductivity of brain tissue was extrapolated from the measured in vivo data and the numerical models. Using this, we present results on the electric field threshold necessary to induce NTIRE lesions (495-510 V/cm) in canine brain tissue using 90 50-mus pulses at 4 Hz. Furthermore, this preliminary study provides some of the necessary numerical tools for using NTIRE as a brain cancer treatment. We also computed the electrical conductivity of brain tissue from the in vivo data (0.12-0.30 S/m) and provide guidelines for treatment planning and execution. Knowledge of the dynamic electrical conductivity of the tissue and electric field that correlates to lesion volume is crucial to ensure predictable complete NTIRE treatment while minimizing damage to surrounding healthy tissue.},
   keywords = {Animals
*Brain
Brain Neoplasms/*therapy
Dogs
Electrochemotherapy/instrumentation/*methods
Models, Biological},
   ISSN = {0022-2631},
   DOI = {10.1007/s00232-010-9284-z},
   year = {2010},
   type = {Journal Article}
}

Nonthermal irreversible electroporation (NTIRE) is a new minimally invasive technique to treat cancer. It is unique because of its nonthermal mechanism of tumor ablation. Intracranial NTIRE procedures involve placing electrodes into the targeted area of the brain and delivering a series of short but intense electric pulses. The electric pulses induce irreversible structural changes in cell membranes, leading to cell death. We correlated NTIRE lesion volumes in normal brain tissue with electric field distributions from comprehensive numerical models. The electrical conductivity of brain tissue was extrapolated from the measured in vivo data and the numerical models. Using this, we present results on the electric field threshold necessary to induce NTIRE lesions (495-510 V/cm) in canine brain tissue using 90 50-mus pulses at 4 Hz. Furthermore, this preliminary study provides some of the necessary numerical tools for using NTIRE as a brain cancer treatment. We also computed the electrical conductivity of brain tissue from the in vivo data (0.12-0.30 S/m) and provide guidelines for treatment planning and execution. Knowledge of the dynamic electrical conductivity of the tissue and electric field that correlates to lesion volume is crucial to ensure predictable complete NTIRE treatment while minimizing damage to surrounding healthy tissue.

@article{RN227,
   author = {Neal, R. E. and Garcia, P. A. and Rossmeisl, J. H. and Davalos, R. V.},
   title = {A study using irreversible electroporation to treat large, irregular tumors in a canine patient},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2010},
   pages = {2747-50},
   note = {Neal, Robert E
Garcia, Paulo A
Rossmeisl, John H
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2010/11/26
Annu Int Conf IEEE Eng Med Biol Soc. 2010;2010:2747-50. doi: 10.1109/IEMBS.2010.5626372.},
   abstract = {Irreversible electroporation (IRE) has shown promise for the therapeutic treatment of focal disease, including tumors. The effects of treatment are dependent on the electric field distribution, which may be predicted with numerical modeling. In order to improve the effectiveness and scope of IRE therapies, techniques must be developed for designing protocols capable of treating large and irregular tumors. We present the findings of a study designing an IRE treatment plan for a canine patient using medical imaging analysis and reconstruction, numerical modeling, and real-time electrode placement guidance. The executed plan was able to alleviate the patient's clinical symptoms without damaging any of the nearby sensitive tissues in a complex heterogeneous environment.},
   keywords = {Algorithms
Animals
Bone Neoplasms/*therapy/veterinary
Diagnostic Imaging
Dogs
Electroporation/*methods
Femur/pathology
Image Processing, Computer-Assisted/methods
Medical Oncology/methods
Models, Theoretical
Quality of Life
Sarcoma/*therapy/veterinary
Tomography, X-Ray Computed/methods},
   ISSN = {2375-7477 (Print)
2375-7477},
   DOI = {10.1109/iembs.2010.5626372},
   year = {2010},
   type = {Journal Article}
}

Irreversible electroporation (IRE) has shown promise for the therapeutic treatment of focal disease, including tumors. The effects of treatment are dependent on the electric field distribution, which may be predicted with numerical modeling. In order to improve the effectiveness and scope of IRE therapies, techniques must be developed for designing protocols capable of treating large and irregular tumors. We present the findings of a study designing an IRE treatment plan for a canine patient using medical imaging analysis and reconstruction, numerical modeling, and real-time electrode placement guidance. The executed plan was able to alleviate the patient's clinical symptoms without damaging any of the nearby sensitive tissues in a complex heterogeneous environment.

@article{RN232,
   author = {Neal, R. E., 2nd and Singh, R. and Hatcher, H. C. and Kock, N. D. and Torti, S. V. and Davalos, R. V.},
   title = {Treatment of breast cancer through the application of irreversible electroporation using a novel minimally invasive single needle electrode},
   journal = {Breast Cancer Res Treat},
   volume = {123},
   number = {1},
   pages = {295-301},
   note = {1573-7217
Neal, Robert E 2nd
Singh, Ravi
Hatcher, Heather C
Kock, Nancy D
Torti, Suzy V
Davalos, Rafael V
R01 CA128428/CA/NCI NIH HHS/United States
T32 CA079448/CA/NCI NIH HHS/United States
R01CA12842/CA/NCI NIH HHS/United States
T32 CA-079448/CA/NCI NIH HHS/United States
R01 CA128428-03/CA/NCI NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Netherlands
2010/03/02
Breast Cancer Res Treat. 2010 Aug;123(1):295-301. doi: 10.1007/s10549-010-0803-5. Epub 2010 Feb 27.},
   abstract = {Irreversible electroporation (IRE) is a therapeutic technology for the ablation of soft tissues using electrodes to deliver intense but short electric pulses across a cell membrane, creating nanopores that lead to cell death. This phenomenon only affects the cell membrane, leaving the extracellular matrix and sensitive structures intact, making it a promising technique for the treatment many types of tumors. In this paper, we present the first in vivo study to achieve tumor regression using a translatable, clinically relevant single needle electrode for treatment administration. Numerical models of the electric field distribution for the protocol used suggest that a 1000 V/cm field threshold is sufficient to treat a tumor, and that the electric field distribution will slightly decrease if the same protocol were used on a tumor deep seated within a human breast. Tumor regression was observed in 5 out of 7 MDA-MB231 human mammary tumors orthotopically implanted in female Nu/Nu mice, with continued growth in controls.},
   keywords = {Animals
Cell Line, Tumor
Electrochemotherapy/*instrumentation/*methods
Electrodes
Female
Humans
Mammary Neoplasms, Experimental/pathology/*therapy
Mice
Mice, Nude
*Needles
Xenograft Model Antitumor Assays},
   ISSN = {0167-6806 (Print)
0167-6806},
   DOI = {10.1007/s10549-010-0803-5},
   year = {2010},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a therapeutic technology for the ablation of soft tissues using electrodes to deliver intense but short electric pulses across a cell membrane, creating nanopores that lead to cell death. This phenomenon only affects the cell membrane, leaving the extracellular matrix and sensitive structures intact, making it a promising technique for the treatment many types of tumors. In this paper, we present the first in vivo study to achieve tumor regression using a translatable, clinically relevant single needle electrode for treatment administration. Numerical models of the electric field distribution for the protocol used suggest that a 1000 V/cm field threshold is sufficient to treat a tumor, and that the electric field distribution will slightly decrease if the same protocol were used on a tumor deep seated within a human breast. Tumor regression was observed in 5 out of 7 MDA-MB231 human mammary tumors orthotopically implanted in female Nu/Nu mice, with continued growth in controls.

@article{RN226,
   author = {Sano, M. B. and Neal, R. E., 2nd and Garcia, P. A. and Gerber, D. and Robertson, J. and Davalos, R. V.},
   title = {Towards the creation of decellularized organ constructs using irreversible electroporation and active mechanical perfusion},
   journal = {Biomed Eng Online},
   volume = {9},
   pages = {83},
   note = {1475-925x
Sano, Michael B
Neal, Robert E 2nd
Garcia, Paulo A
Gerber, David
Robertson, John
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
England
2010/12/15
Biomed Eng Online. 2010 Dec 10;9:83. doi: 10.1186/1475-925X-9-83.},
   abstract = {BACKGROUND: Despite advances in transplant surgery and general medicine, the number of patients awaiting transplant organs continues to grow, while the supply of organs does not. This work outlines a method of organ decellularization using non-thermal irreversible electroporation (N-TIRE) which, in combination with reseeding, may help supplement the supply of organs for transplant. METHODS: In our study, brief but intense electric pulses were applied to porcine livers while under active low temperature cardio-emulation perfusion. Histological analysis and lesion measurements were used to determine the effects of the pulses in decellularizing the livers as a first step towards the development of extracellular scaffolds that may be used with stem cell reseeding. A dynamic conductivity numerical model was developed to simulate the treatment parameters used and determine an irreversible electroporation threshold. RESULTS: Ninety-nine individual 1000 V/cm 100-μs square pulses with repetition rates between 0.25 and 4 Hz were found to produce a lesion within 24 hours post-treatment. The livers maintained intact bile ducts and vascular structures while demonstrating hepatocytic cord disruption and cell delamination from cord basal laminae after 24 hours of perfusion. A numerical model found an electric field threshold of 423 V/cm under specific experimental conditions, which may be used in the future to plan treatments for the decellularization of entire organs. Analysis of the pulse repetition rate shows that the largest treated area and the lowest interstitial density score was achieved for a pulse frequency of 1 Hz. After 24 hours of perfusion, a maximum density score reduction of 58.5 percent had been achieved. CONCLUSIONS: This method is the first effort towards creating decellularized tissue scaffolds that could be used for organ transplantation using N-TIRE. In addition, it provides a versatile platform to study the effects of pulse parameters such as pulse length, repetition rate, and field strength on whole organ structures.},
   keywords = {Animals
Electroporation/*methods
Humans
Liver/blood supply/cytology
*Mechanical Phenomena
Perfusion/*methods
Swine
Tissue Engineering/*methods
Tissue Scaffolds},
   ISSN = {1475-925x},
   DOI = {10.1186/1475-925x-9-83},
   year = {2010},
   type = {Journal Article}
}

BACKGROUND: Despite advances in transplant surgery and general medicine, the number of patients awaiting transplant organs continues to grow, while the supply of organs does not. This work outlines a method of organ decellularization using non-thermal irreversible electroporation (N-TIRE) which, in combination with reseeding, may help supplement the supply of organs for transplant. METHODS: In our study, brief but intense electric pulses were applied to porcine livers while under active low temperature cardio-emulation perfusion. Histological analysis and lesion measurements were used to determine the effects of the pulses in decellularizing the livers as a first step towards the development of extracellular scaffolds that may be used with stem cell reseeding. A dynamic conductivity numerical model was developed to simulate the treatment parameters used and determine an irreversible electroporation threshold. RESULTS: Ninety-nine individual 1000 V/cm 100-μs square pulses with repetition rates between 0.25 and 4 Hz were found to produce a lesion within 24 hours post-treatment. The livers maintained intact bile ducts and vascular structures while demonstrating hepatocytic cord disruption and cell delamination from cord basal laminae after 24 hours of perfusion. A numerical model found an electric field threshold of 423 V/cm under specific experimental conditions, which may be used in the future to plan treatments for the decellularization of entire organs. Analysis of the pulse repetition rate shows that the largest treated area and the lowest interstitial density score was achieved for a pulse frequency of 1 Hz. After 24 hours of perfusion, a maximum density score reduction of 58.5 percent had been achieved. CONCLUSIONS: This method is the first effort towards creating decellularized tissue scaffolds that could be used for organ transplantation using N-TIRE. In addition, it provides a versatile platform to study the effects of pulse parameters such as pulse length, repetition rate, and field strength on whole organ structures.

@article{RN231,
   author = {Sano, M. B. and Rojas, A. D. and Gatenholm, P. and Davalos, R. V.},
   title = {Electromagnetically controlled biological assembly of aligned bacterial cellulose nanofibers},
   journal = {Ann Biomed Eng},
   volume = {38},
   number = {8},
   pages = {2475-84},
   note = {1573-9686
Sano, Michael B
Rojas, Andrea D
Gatenholm, Paul
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2010/03/20
Ann Biomed Eng. 2010 Aug;38(8):2475-84. doi: 10.1007/s10439-010-9999-0. Epub 2010 Mar 19.},
   abstract = {We have developed a new biofabrication process in which the precise control of bacterial motion is used to fabricate customizable networks of cellulose nanofibrils. This article describes how the motion of Acetobacter xylinum can be controlled by electric fields while the bacteria simultaneously produce nanocellulose, resulting in networks with aligned fibers. Since the electrolysis of water due to the application of electric fields produces the oxygen in the culture media far from the liquid-air boundary, aerobic cellulose production in 3D structures is readily achievable. Five separate sets of experiments were conducted to demonstrate the assembly of nanocellulose by A. xylinum in the presence of electric fields in micro- and macro-environments. This study demonstrates a new concept of bottom up material synthesis by the control of a biological assembly process.},
   keywords = {Air
Bacteria
Cellulose/*biosynthesis/ultrastructure
Culture Media
Electricity
Gluconacetobacter xylinus/*metabolism
*Magnetics
*Nanofibers
Oxygen/metabolism},
   ISSN = {0090-6964},
   DOI = {10.1007/s10439-010-9999-0},
   year = {2010},
   type = {Journal Article}
}

We have developed a new biofabrication process in which the precise control of bacterial motion is used to fabricate customizable networks of cellulose nanofibrils. This article describes how the motion of Acetobacter xylinum can be controlled by electric fields while the bacteria simultaneously produce nanocellulose, resulting in networks with aligned fibers. Since the electrolysis of water due to the application of electric fields produces the oxygen in the culture media far from the liquid-air boundary, aerobic cellulose production in 3D structures is readily achievable. Five separate sets of experiments were conducted to demonstrate the assembly of nanocellulose by A. xylinum in the presence of electric fields in micro- and macro-environments. This study demonstrates a new concept of bottom up material synthesis by the control of a biological assembly process.

@article{RN233,
   author = {Shafiee, H. and Sano, M. B. and Henslee, E. A. and Caldwell, J. L. and Davalos, R. V.},
   title = {Selective isolation of live/dead cells using contactless dielectrophoresis (cDEP)},
   journal = {Lab Chip},
   volume = {10},
   number = {4},
   pages = {438-45},
   note = {Shafiee, Hadi
Sano, Michael B
Henslee, Erin A
Caldwell, John L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
England
2010/02/04
Lab Chip. 2010 Feb 21;10(4):438-45. doi: 10.1039/b920590j. Epub 2010 Jan 19.},
   abstract = {Contactless dielectrophoresis (cDEP) is a recently developed method of cell manipulation in which the electrodes are physically isolated from the sample. Here we present two microfluidic devices capable of selectively isolating live human leukemia cells from dead cells utilizing their electrical signatures. The effect of different voltages and frequencies on the gradient of the electric field and device performance was investigated numerically and validated experimentally. With these prototype devices we were able to achieve greater than 95% removal efficiency at 0.2-0.5 mm s(-1) with 100% selectivity between live and dead cells. In conjunction with enrichment, cDEP could be integrated with other technologies to yield fully automated lab-on-a-chip systems capable of sensing, sorting, and identifying rare cells.},
   keywords = {Animals
Cell Death
Cell Line, Tumor
Cell Separation/instrumentation/*methods
Cell Survival
Electric Conductivity
Electrophoresis
Humans},
   ISSN = {1473-0197 (Print)
1473-0189},
   DOI = {10.1039/b920590j},
   year = {2010},
   type = {Journal Article}
}

Contactless dielectrophoresis (cDEP) is a recently developed method of cell manipulation in which the electrodes are physically isolated from the sample. Here we present two microfluidic devices capable of selectively isolating live human leukemia cells from dead cells utilizing their electrical signatures. The effect of different voltages and frequencies on the gradient of the electric field and device performance was investigated numerically and validated experimentally. With these prototype devices we were able to achieve greater than 95% removal efficiency at 0.2-0.5 mm s(-1) with 100% selectivity between live and dead cells. In conjunction with enrichment, cDEP could be integrated with other technologies to yield fully automated lab-on-a-chip systems capable of sensing, sorting, and identifying rare cells.

@article{RN235,
   author = {Arena, C. B. and Rylander, M. N. and Davalos, R. V.},
   title = {Theoretical study for the treatment of pancreatic cancer using electric pulses},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2009},
   pages = {5997-6000},
   note = {Arena, Christopher B
Rylander, Marissa Nichole
Davalos, Rafael V
Journal Article
United States
2009/12/08
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:5997-6000. doi: 10.1109/IEMBS.2009.5333140.},
   abstract = {Through the development of numerical models, this study describes how Non-Thermal Irreversible Electroporation (N-TIRE) of the pancreas presents certain challenges that can be alleviated through the use of non-puncturing plate electrodes and ultra-short electric pulses.},
   keywords = {Computer Simulation
Dose-Response Relationship, Radiation
Electric Stimulation Therapy/*methods
Electromagnetic Fields
Humans
*Models, Biological
Pancreas/*physiopathology/radiation effects
Pancreatic Neoplasms/*physiopathology/*therapy
Radiation Dosage
Therapy, Computer-Assisted/*methods
Treatment Outcome},
   ISSN = {2375-7477 (Print)
2375-7477},
   DOI = {10.1109/iembs.2009.5333140},
   year = {2009},
   type = {Journal Article}
}

Through the development of numerical models, this study describes how Non-Thermal Irreversible Electroporation (N-TIRE) of the pancreas presents certain challenges that can be alleviated through the use of non-puncturing plate electrodes and ultra-short electric pulses.

@article{RN234,
   author = {Garcia, P. A. and Rossmeisl, J. H., Jr. and Robertson, J. and Ellis, T. L. and Davalos, R. V.},
   title = {Pilot study of irreversible electroporation for intracranial surgery},
   journal = {Annu Int Conf IEEE Eng Med Biol Soc},
   volume = {2009},
   pages = {6513-6},
   note = {Garcia, Paulo A
Rossmeisl, John H Jr
Robertson, John
Ellis, Thomas L
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2009/12/08
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:6513-6. doi: 10.1109/IEMBS.2009.5333141.},
   abstract = {Irreversible electroporation (IRE) is a new minimally invasive technique to treat cancer using intense but short electric pulses. This technique is unique because of its non-thermal mechanism of tissue ablation. Furthermore it can be predicted with numerical models and can be confirmed with ultrasound and MRI. We present some preliminary results on the safety of using irreversible electroporation for canine brain surgery. We also present the electric field (460 V/cm - 560 V/cm) necessary for focal ablation of canine brain tissue and provide some guidelines for treatment planning and execution. This preliminary study is the first step towards using irreversible electroporation as a brain cancer treatment.},
   keywords = {Animals
Brain/*pathology/*surgery
Dogs
Electroporation/methods
Electrosurgery/*methods
Neurosurgical Procedures/*methods
Pilot Projects},
   ISSN = {2375-7477 (Print)
2375-7477},
   DOI = {10.1109/iembs.2009.5333141},
   year = {2009},
   type = {Journal Article}
}

Irreversible electroporation (IRE) is a new minimally invasive technique to treat cancer using intense but short electric pulses. This technique is unique because of its non-thermal mechanism of tissue ablation. Furthermore it can be predicted with numerical models and can be confirmed with ultrasound and MRI. We present some preliminary results on the safety of using irreversible electroporation for canine brain surgery. We also present the electric field (460 V/cm - 560 V/cm) necessary for focal ablation of canine brain tissue and provide some guidelines for treatment planning and execution. This preliminary study is the first step towards using irreversible electroporation as a brain cancer treatment.

@article{RN236,
   author = {Neal, R. E., 2nd and Davalos, R. V.},
   title = {The feasibility of irreversible electroporation for the treatment of breast cancer and other heterogeneous systems},
   journal = {Ann Biomed Eng},
   volume = {37},
   number = {12},
   pages = {2615-25},
   note = {1573-9686
Neal, Robert E 2nd
Davalos, Rafael V
Journal Article
United States
2009/09/17
Ann Biomed Eng. 2009 Dec;37(12):2615-25. doi: 10.1007/s10439-009-9796-9. Epub 2009 Sep 15.},
   abstract = {Developments in breast cancer therapies show potential for replacing simple and radical mastectomies with less invasive techniques. Localized thermal techniques encounter difficulties, preventing their widespread acceptance as replacements for surgical resection. Irreversible electroporation (IRE) is a non-thermal, minimally invasive focal ablation technique capable of killing tissue using electric pulses to create irrecoverable nano-scale pores in the cell membrane. Its unique mechanism of cell death exhibits benefits over thermal techniques including rapid lesion creation and resolution, preservation of the extracellular matrix and major vasculature, and reduced scarring. This study investigates applying IRE to treat primary breast tumors located within a fatty extracellular matrix despite IREs dependence on the heterogeneous properties of tissue. In vitro experiments were performed on MDA-MB-231 human mammary carcinoma cells to determine a baseline electric field threshold (1000 V/cm) to cause IRE for a given set of pulse parameters. The threshold was incorporated into a three-dimensional numerical model of a heterogeneous system to simulate IRE treatments. Treatment-relevant protocols were found to be capable of treating targeted tissue over a large range of heterogeneous properties without inducing significant thermal damage, making IRE a potential modality for successfully treating breast cancer. Information from this study may be used for the investigation of other heterogeneous tissue applications for IRE.},
   keywords = {Breast Neoplasms/pathology/*physiopathology/*therapy
Cell Line, Tumor
Computer Simulation
Electroporation/*methods
Electrosurgery/*methods
Feasibility Studies
Female
Humans
*Models, Biological
Therapy, Computer-Assisted/*methods
Treatment Outcome},
   ISSN = {0090-6964},
   DOI = {10.1007/s10439-009-9796-9},
   year = {2009},
   type = {Journal Article}
}

Developments in breast cancer therapies show potential for replacing simple and radical mastectomies with less invasive techniques. Localized thermal techniques encounter difficulties, preventing their widespread acceptance as replacements for surgical resection. Irreversible electroporation (IRE) is a non-thermal, minimally invasive focal ablation technique capable of killing tissue using electric pulses to create irrecoverable nano-scale pores in the cell membrane. Its unique mechanism of cell death exhibits benefits over thermal techniques including rapid lesion creation and resolution, preservation of the extracellular matrix and major vasculature, and reduced scarring. This study investigates applying IRE to treat primary breast tumors located within a fatty extracellular matrix despite IREs dependence on the heterogeneous properties of tissue. In vitro experiments were performed on MDA-MB-231 human mammary carcinoma cells to determine a baseline electric field threshold (1000 V/cm) to cause IRE for a given set of pulse parameters. The threshold was incorporated into a three-dimensional numerical model of a heterogeneous system to simulate IRE treatments. Treatment-relevant protocols were found to be capable of treating targeted tissue over a large range of heterogeneous properties without inducing significant thermal damage, making IRE a potential modality for successfully treating breast cancer. Information from this study may be used for the investigation of other heterogeneous tissue applications for IRE.

@article{RN238,
   author = {Shafiee, H. and Caldwell, J. L. and Sano, M. B. and Davalos, R. V.},
   title = {Contactless dielectrophoresis: a new technique for cell manipulation},
   journal = {Biomed Microdevices},
   volume = {11},
   number = {5},
   pages = {997-1006},
   note = {1572-8781
Shafiee, Hadi
Caldwell, John L
Sano, Michael B
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2009/05/06
Biomed Microdevices. 2009 Oct;11(5):997-1006. doi: 10.1007/s10544-009-9317-5. Epub 2009 May 5.},
   abstract = {Dielectrophoresis (DEP) has become a promising technique to separate and identify cells and microparticles suspended in a medium based on their size or electrical properties. Presented herein is a new technique to provide the non-uniform electric field required for DEP that does not require electrodes to contact the sample fluid. In our method, electrodes are capacitively-coupled to a fluidic channel through dielectric barriers; the application of a high-frequency electric field to these electrodes then induces an electric field in the channel. This technique combines the cell manipulation abilities of traditional DEP with the ease of fabrication found in insulator-based technologies. A microfluidic device was fabricated based on this principle to determine the feasibility of cell manipulations through contactless DEP (cDEP). We were able to demonstrate cell responses unique to the DEP effect in three separate cell lines. These results illustrate the potential for this technique to identify cells through their electrical properties without fear of contamination from electrodes.},
   keywords = {Cell Line, Tumor
Cell Separation/*instrumentation
Dimethylpolysiloxanes/chemistry
Electric Impedance
Electrodes
Electrophoresis/*instrumentation
Humans
Microfluidic Analytical Techniques/*instrumentation
Models, Theoretical
Rotation},
   ISSN = {1387-2176},
   DOI = {10.1007/s10544-009-9317-5},
   year = {2009},
   type = {Journal Article}
}

Dielectrophoresis (DEP) has become a promising technique to separate and identify cells and microparticles suspended in a medium based on their size or electrical properties. Presented herein is a new technique to provide the non-uniform electric field required for DEP that does not require electrodes to contact the sample fluid. In our method, electrodes are capacitively-coupled to a fluidic channel through dielectric barriers; the application of a high-frequency electric field to these electrodes then induces an electric field in the channel. This technique combines the cell manipulation abilities of traditional DEP with the ease of fabrication found in insulator-based technologies. A microfluidic device was fabricated based on this principle to determine the feasibility of cell manipulations through contactless DEP (cDEP). We were able to demonstrate cell responses unique to the DEP effect in three separate cell lines. These results illustrate the potential for this technique to identify cells through their electrical properties without fear of contamination from electrodes.

@article{RN237,
   author = {Shafiee, H. and Garcia, P. A. and Davalos, R. V.},
   title = {A preliminary study to delineate irreversible electroporation from thermal damage using the arrhenius equation},
   journal = {J Biomech Eng},
   volume = {131},
   number = {7},
   pages = {074509},
   note = {Shafiee, Hadi
Garcia, Paulo A
Davalos, Rafael V
Journal Article
Research Support, Non-U.S. Gov't
United States
2009/07/31
J Biomech Eng. 2009 Jul;131(7):074509. doi: 10.1115/1.3143027.},
   abstract = {Intense but short electrical fields can increase the permeability of the cell membrane in a process referred to as electroporation. Reversible electroporation has become an important tool in biotechnology and medicine. The various applications of reversible electroporation require cells to survive the procedure, and therefore the occurrence of irreversible electroporation (IRE), following which cells die, is obviously undesirable. However, for the past few years, IRE has begun to emerge as an important minimally invasive nonthermal ablation technique in its own right as a method to treat tumors and arrhythmogenic regions in the heart. IRE had been studied primarily to define the upper limit of electrical parameters that induce reversible electroporation. Thus, the delineation of IRE from thermal damage due to Joule heating has not been thoroughly investigated. The goal of this study was to express the upper bound of IRE (onset of thermal damage) theoretically as a function of physical properties and electrical pulse parameters. Electrical pulses were applied to THP-1 human monocyte cells, and the percentage of irreversibly electroporated (dead) cells in the sample was quantified. We also determined the upper bound of IRE (onset of thermal damage) through a theoretical calculation that takes into account the physical properties of the sample and the electric pulse characteristics. Our experimental results were achieved below the theoretical curve for the onset of thermal damage. These results confirm that the region to induce IRE without thermal damage is substantial. We believe that our new theoretical analysis will allow researchers to optimize IRE parameters without inducing deleterious thermal effects.},
   keywords = {Cell Line
Cell Survival/*radiation effects
Computer Simulation
Electromagnetic Fields
Electroporation/*methods
Hot Temperature
Humans
*Models, Biological
Monocytes/cytology/*physiology/*radiation effects
Pilot Projects},
   ISSN = {0148-0731 (Print)
0148-0731},
   DOI = {10.1115/1.3143027},
   year = {2009},
   type = {Journal Article}
}

Intense but short electrical fields can increase the permeability of the cell membrane in a process referred to as electroporation. Reversible electroporation has become an important tool in biotechnology and medicine. The various applications of reversible electroporation require cells to survive the procedure, and therefore the occurrence of irreversible electroporation (IRE), following which cells die, is obviously undesirable. However, for the past few years, IRE has begun to emerge as an important minimally invasive nonthermal ablation technique in its own right as a method to treat tumors and arrhythmogenic regions in the heart. IRE had been studied primarily to define the upper limit of electrical parameters that induce reversible electroporation. Thus, the delineation of IRE from thermal damage due to Joule heating has not been thoroughly investigated. The goal of this study was to express the upper bound of IRE (onset of thermal damage) theoretically as a function of physical properties and electrical pulse parameters. Electrical pulses were applied to THP-1 human monocyte cells, and the percentage of irreversibly electroporated (dead) cells in the sample was quantified. We also determined the upper bound of IRE (onset of thermal damage) through a theoretical calculation that takes into account the physical properties of the sample and the electric pulse characteristics. Our experimental results were achieved below the theoretical curve for the onset of thermal damage. These results confirm that the region to induce IRE without thermal damage is substantial. We believe that our new theoretical analysis will allow researchers to optimize IRE parameters without inducing deleterious thermal effects.

@article{RN243,
   author = {Davalos, R. V. and McGraw, G. J. and Wallow, T. I. and Morales, A. M. and Krafcik, K. L. and Fintschenko, Y. and Cummings, E. B. and Simmons, B. A.},
   title = {Performance impact of dynamic surface coatings on polymeric insulator-based dielectrophoretic particle separators},
   journal = {Anal Bioanal Chem},
   volume = {390},
   number = {3},
   pages = {847-55},
   note = {1618-2650
Davalos, Rafael V
McGraw, Gregory J
Wallow, Thomas I
Morales, Alfredo M
Krafcik, Karen L
Fintschenko, Yolanda
Cummings, Eric B
Simmons, Blake A
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Germany
2007/07/13
Anal Bioanal Chem. 2008 Feb;390(3):847-55. doi: 10.1007/s00216-007-1426-5. Epub 2007 Jul 12.},
   abstract = {Efficient and robust particle separation and enrichment techniques are critical for a diverse range of lab-on-a-chip analytical devices including pathogen detection, sample preparation, high-throughput particle sorting, and biomedical diagnostics. Previously, using insulator-based dielectrophoresis (iDEP) in microfluidic glass devices, we demonstrated simultaneous particle separation and concentration of various biological organisms, polymer microbeads, and viruses. As an alternative to glass, we evaluate the performance of similar iDEP structures produced in polymer-based microfluidic devices. There are numerous processing and operational advantages that motivate our transition to polymers such as the availability of numerous innate chemical compositions for tailoring performance, mechanical robustness, economy of scale, and ease of thermoforming and mass manufacturing. The polymer chips we have evaluated are fabricated through an injection molding process of the commercially available cyclic olefin copolymer Zeonor 1060R. This publication is the first to demonstrate insulator-based dielectrophoretic biological particle differentiation in a polymeric device injection molded from a silicon master. The results demonstrate that the polymer devices achieve the same performance metrics as glass devices. We also demonstrate an effective means of enhancing performance of these microsystems in terms of system power demand through the use of a dynamic surface coating. We demonstrate that the commercially available nonionic block copolymer surfactant, Pluronic F127, has a strong interaction with the cyclic olefin copolymer at very low concentrations, positively impacting performance by decreasing the electric field necessary to achieve particle trapping by an order of magnitude. The presence of this dynamic surface coating, therefore, lowers the power required to operate such devices and minimizes Joule heating. The results of this study demonstrate that iDEP polymeric microfluidic devices with surfactant coatings provide an affordable engineering strategy for selective particle enrichment and sorting.},
   keywords = {Bacillus subtilis/metabolism
Bacillus thuringiensis/metabolism
Biocompatible Materials/*chemistry
Electrochemistry/methods
*Electrophoresis, Microchip
Equipment Design
Hot Temperature
Kinetics
Microfluidic Analytical Techniques
*Microfluidics
Poloxamer/chemistry
Polymers/*chemistry
Surface Properties
Surface-Active Agents
Tissue Engineering/methods},
   ISSN = {1618-2642},
   DOI = {10.1007/s00216-007-1426-5},
   year = {2008},
   type = {Journal Article}
}

Efficient and robust particle separation and enrichment techniques are critical for a diverse range of lab-on-a-chip analytical devices including pathogen detection, sample preparation, high-throughput particle sorting, and biomedical diagnostics. Previously, using insulator-based dielectrophoresis (iDEP) in microfluidic glass devices, we demonstrated simultaneous particle separation and concentration of various biological organisms, polymer microbeads, and viruses. As an alternative to glass, we evaluate the performance of similar iDEP structures produced in polymer-based microfluidic devices. There are numerous processing and operational advantages that motivate our transition to polymers such as the availability of numerous innate chemical compositions for tailoring performance, mechanical robustness, economy of scale, and ease of thermoforming and mass manufacturing. The polymer chips we have evaluated are fabricated through an injection molding process of the commercially available cyclic olefin copolymer Zeonor 1060R. This publication is the first to demonstrate insulator-based dielectrophoretic biological particle differentiation in a polymeric device injection molded from a silicon master. The results demonstrate that the polymer devices achieve the same performance metrics as glass devices. We also demonstrate an effective means of enhancing performance of these microsystems in terms of system power demand through the use of a dynamic surface coating. We demonstrate that the commercially available nonionic block copolymer surfactant, Pluronic F127, has a strong interaction with the cyclic olefin copolymer at very low concentrations, positively impacting performance by decreasing the electric field necessary to achieve particle trapping by an order of magnitude. The presence of this dynamic surface coating, therefore, lowers the power required to operate such devices and minimizes Joule heating. The results of this study demonstrate that iDEP polymeric microfluidic devices with surfactant coatings provide an affordable engineering strategy for selective particle enrichment and sorting.

@article{RN241,
   author = {James, C. D. and Reuel, N. and Lee, E. S. and Davalos, R. V. and Mani, S. S. and Carroll-Portillo, A. and Rebeil, R. and Martino, A. and Apblett, C. A.},
   title = {Impedimetric and optical interrogation of single cells in a microfluidic device for real-time viability and chemical response assessment},
   journal = {Biosens Bioelectron},
   volume = {23},
   number = {6},
   pages = {845-51},
   note = {James, Conrad D
Reuel, Nigel
Lee, Eunice S
Davalos, Rafael V
Mani, Seethambal S
Carroll-Portillo, Amanda
Rebeil, Roberto
Martino, Anthony
Apblett, Christopher A
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
England
2007/10/16
Biosens Bioelectron. 2008 Jan 18;23(6):845-51. doi: 10.1016/j.bios.2007.08.022. Epub 2007 Sep 6.},
   abstract = {We report here a non-invasive, reversible method for interrogating single cells in a microfluidic flow-through system. Impedance spectroscopy of cells held at a micron-sized pore under negative pressure is demonstrated and used to determine the presence and viability of the captured cell. The cell capture pore is optimized for electrical response and mechanical interfacing to a cell using a deposited layer of parylene. Changes in the mechanical interface between the cell and the chip due to chemical exposure or environmental changes can also be assessed. Here, we monitored the change in adhesion/spreading of RAW264.7 macrophages in response to the immune stimulant lipopolysaccharide (LPS). This method enables selective, reversible, and quantitative long-term impedance measurements on single cells. The fully sealed electrofluidic assembly is compatible with long-term cell culturing, and could be modified to incorporate single cell lysis and subsequent intracellular separation and analysis.},
   keywords = {Cell Survival
Cells, Cultured
Electric Impedance
Lipopolysaccharides/pharmacology
Macrophages/drug effects/*physiology
*Microfluidic Analytical Techniques
Optics and Photonics
Spectrum Analysis},
   ISSN = {0956-5663 (Print)
0956-5663},
   DOI = {10.1016/j.bios.2007.08.022},
   year = {2008},
   type = {Journal Article}
}

We report here a non-invasive, reversible method for interrogating single cells in a microfluidic flow-through system. Impedance spectroscopy of cells held at a micron-sized pore under negative pressure is demonstrated and used to determine the presence and viability of the captured cell. The cell capture pore is optimized for electrical response and mechanical interfacing to a cell using a deposited layer of parylene. Changes in the mechanical interface between the cell and the chip due to chemical exposure or environmental changes can also be assessed. Here, we monitored the change in adhesion/spreading of RAW264.7 macrophages in response to the immune stimulant lipopolysaccharide (LPS). This method enables selective, reversible, and quantitative long-term impedance measurements on single cells. The fully sealed electrofluidic assembly is compatible with long-term cell culturing, and could be modified to incorporate single cell lysis and subsequent intracellular separation and analysis.

@article{RN239,
   author = {Sabounchi, P. and Morales, A. M. and Ponce, P. and Lee, L. P. and Simmons, B. A. and Davalos, R. V.},
   title = {Sample concentration and impedance detection on a microfluidic polymer chip},
   journal = {Biomed Microdevices},
   volume = {10},
   number = {5},
   pages = {661-70},
   note = {Sabounchi, Poorya
Morales, Alfredo M
Ponce, Pierre
Lee, Luke P
Simmons, Blake A
Davalos, Rafael V
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
United States
2008/05/20
Biomed Microdevices. 2008 Oct;10(5):661-70. doi: 10.1007/s10544-008-9177-4.},
   abstract = {We present an on-chip microfluidic sample concentrator and detection triggering system for microparticles based on a combination of insulator-based dielectrophoresis (iDEP) and electrical impedance measurement. This platform operates by first using iDEP to selectively concentrate microparticles of interest based on their electrical and physiological characteristics in a primary fluidic channel; the concentrated microparticles are then directed into a side channel configured for particle detection using electrical impedance measurements with embedded electrodes. This is the first study showing iDEP concentration with subsequent sample diversion down an analysis channel and is the first to demonstrate iDEP in the presence of pressure driven flow. Experimental results demonstrating the capabilities of this platform were obtained using polystyrene microspheres and Bacillus subtilis spores. The feasibility of selective iDEP trapping and impedance detection of these particles was demonstrated. The system is intended for use as a front-end unit that can be easily paired with multiple biodetection/bioidentification systems. This platform is envisioned to act as a decision-making component to determine if confirmatory downstream identification assays are required. Without a front end component that triggers downstream analysis only when necessary, bio-identification systems (based on current analytical technologies such as PCR and immunoassays) may incur prohibitively high costs to operate due to continuous consumption of expensive reagents.},
   keywords = {Bacillus subtilis/metabolism
Biosensing Techniques/*instrumentation/*methods
Electric Impedance
Electrochemistry/methods
Electrophoresis, Microchip
Equipment Design
Feasibility Studies
Microchemistry/*methods
*Microfluidic Analytical Techniques/instrumentation/methods
Microfluidics/*methods
Microspheres
Particle Size
Polystyrenes/chemistry
Spores, Bacterial/metabolism},
   ISSN = {1387-2176 (Print)
1387-2176},
   DOI = {10.1007/s10544-008-9177-4},
   year = {2008},
   type = {Journal Article}
}

We present an on-chip microfluidic sample concentrator and detection triggering system for microparticles based on a combination of insulator-based dielectrophoresis (iDEP) and electrical impedance measurement. This platform operates by first using iDEP to selectively concentrate microparticles of interest based on their electrical and physiological characteristics in a primary fluidic channel; the concentrated microparticles are then directed into a side channel configured for particle detection using electrical impedance measurements with embedded electrodes. This is the first study showing iDEP concentration with subsequent sample diversion down an analysis channel and is the first to demonstrate iDEP in the presence of pressure driven flow. Experimental results demonstrating the capabilities of this platform were obtained using polystyrene microspheres and Bacillus subtilis spores. The feasibility of selective iDEP trapping and impedance detection of these particles was demonstrated. The system is intended for use as a front-end unit that can be easily paired with multiple biodetection/bioidentification systems. This platform is envisioned to act as a decision-making component to determine if confirmatory downstream identification assays are required. Without a front end component that triggers downstream analysis only when necessary, bio-identification systems (based on current analytical technologies such as PCR and immunoassays) may incur prohibitively high costs to operate due to continuous consumption of expensive reagents.

@article{RN240,
   author = {Al-Sakere, B. and André, F. and Bernat, C. and Connault, E. and Opolon, P. and Davalos, R. V. and Rubinsky, B. and Mir, L. M.},
   title = {Tumor ablation with irreversible electroporation},
   journal = {PLoS One},
   volume = {2},
   number = {11},
   pages = {e1135},
   note = {1932-6203
Al-Sakere, Bassim
André, Franck
Bernat, Claire
Connault, Elisabeth
Opolon, Paule
Davalos, Rafael V
Rubinsky, Boris
Mir, Lluis M
R01 RR018961/RR/NCRR NIH HHS/United States
R01 RR018961-04/RR/NCRR NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
United States
2007/11/09
PLoS One. 2007 Nov 7;2(11):e1135. doi: 10.1371/journal.pone.0001135.},
   abstract = {We report the first successful use of irreversible electroporation for the minimally invasive treatment of aggressive cutaneous tumors implanted in mice. Irreversible electroporation is a newly developed non-thermal tissue ablation technique in which certain short duration electrical fields are used to permanently permeabilize the cell membrane, presumably through the formation of nanoscale defects in the cell membrane. Mathematical models of the electrical and thermal fields that develop during the application of the pulses were used to design an efficient treatment protocol with minimal heating of the tissue. Tumor regression was confirmed by histological studies which also revealed that it occurred as a direct result of irreversible cell membrane permeabilization. Parametric studies show that the successful outcome of the procedure is related to the applied electric field strength, the total pulse duration as well as the temporal mode of delivery of the pulses. Our best results were obtained using plate electrodes to deliver across the tumor 80 pulses of 100 micros at 0.3 Hz with an electrical field magnitude of 2500 V/cm. These conditions induced complete regression in 12 out of 13 treated tumors, (92%), in the absence of tissue heating. Irreversible electroporation is thus a new effective modality for non-thermal tumor ablation.},
   keywords = {Animals
Cell Line, Tumor
DNA Damage
*Electroporation
Immunohistochemistry
In Situ Nick-End Labeling
Mice
Mice, Inbred C57BL
Sarcoma, Experimental/*therapy
Temperature},
   ISSN = {1932-6203},
   DOI = {10.1371/journal.pone.0001135},
   year = {2007},
   type = {Journal Article}
}

We report the first successful use of irreversible electroporation for the minimally invasive treatment of aggressive cutaneous tumors implanted in mice. Irreversible electroporation is a newly developed non-thermal tissue ablation technique in which certain short duration electrical fields are used to permanently permeabilize the cell membrane, presumably through the formation of nanoscale defects in the cell membrane. Mathematical models of the electrical and thermal fields that develop during the application of the pulses were used to design an efficient treatment protocol with minimal heating of the tissue. Tumor regression was confirmed by histological studies which also revealed that it occurred as a direct result of irreversible cell membrane permeabilization. Parametric studies show that the successful outcome of the procedure is related to the applied electric field strength, the total pulse duration as well as the temporal mode of delivery of the pulses. Our best results were obtained using plate electrodes to deliver across the tumor 80 pulses of 100 micros at 0.3 Hz with an electrical field magnitude of 2500 V/cm. These conditions induced complete regression in 12 out of 13 treated tumors, (92%), in the absence of tissue heating. Irreversible electroporation is thus a new effective modality for non-thermal tumor ablation.

@article{RN242,
   author = {Edd, J. F. and Davalos, R. V.},
   title = {Mathematical modeling of irreversible electroporation for treatment planning},
   journal = {Technol Cancer Res Treat},
   volume = {6},
   number = {4},
   pages = {275-86},
   note = {Edd, Jon F
Davalos, Rafael V
Journal Article
United States
2007/08/03
Technol Cancer Res Treat. 2007 Aug;6(4):275-86. doi: 10.1177/153303460700600403.},
   abstract = {Irreversible Electroporation (IRE) is a new drug-free method to ablate undesirable tissue of particular use in cancer therapy. IRE achieves cell death within the targeted tissue through a series of electric pulses that elevate the transmembrane potentials to an extent that permanently damages the lipid bilayers throughout the treated region. Although the IRE procedure is easy to perform, treatment planning is complicated by the fact that the electric field distribution within the tissue, the greatest single factor controlling the extents of IRE, depends non-trivially on the electrode configuration, pulse parameters and any tissue heterogeneities. To address this difficulty, we instruct on how to properly model IRE and discuss the benefit of modeling in designing treatment protocols. The necessary theoretical basis is introduced and discussed through the detailed analysis of two classic dual-electrode configurations from electrochemotherapy: coaxial disk electrodes and parallel needle electrodes. Dimensionless figures for these cases are also provided that allow cell constants, treated areas, and the details of heating to be determined for a wide range of conditions, for uniform tissues, simply by plugging in the appropriate physical property values and pulse parameters such as electrode spacing, size, and pulse amplitude. Complexities, such as heterogeneous tissues and changes in conductivity due to electroporation, are also discussed. The synthesis of these details can be used directly by surgeons in treatment planning. Irreversible electroporation is a promising new technique to treat cancer in a targeted manner without the use of drugs; however, it does require a detailed understanding of how electric currents flow within biological tissues. By providing the understanding and tools necessary to design an IRE protocol, this study seeks to facilitate the translation of this new and exciting cancer therapy into clinical practice.},
   keywords = {Electroporation/*methods
Hot Temperature/*therapeutic use
Humans
*Models, Biological
Neoplasms/*surgery},
   ISSN = {1533-0346 (Print)
1533-0338},
   DOI = {10.1177/153303460700600403},
   year = {2007},
   type = {Journal Article}
}

Irreversible Electroporation (IRE) is a new drug-free method to ablate undesirable tissue of particular use in cancer therapy. IRE achieves cell death within the targeted tissue through a series of electric pulses that elevate the transmembrane potentials to an extent that permanently damages the lipid bilayers throughout the treated region. Although the IRE procedure is easy to perform, treatment planning is complicated by the fact that the electric field distribution within the tissue, the greatest single factor controlling the extents of IRE, depends non-trivially on the electrode configuration, pulse parameters and any tissue heterogeneities. To address this difficulty, we instruct on how to properly model IRE and discuss the benefit of modeling in designing treatment protocols. The necessary theoretical basis is introduced and discussed through the detailed analysis of two classic dual-electrode configurations from electrochemotherapy: coaxial disk electrodes and parallel needle electrodes. Dimensionless figures for these cases are also provided that allow cell constants, treated areas, and the details of heating to be determined for a wide range of conditions, for uniform tissues, simply by plugging in the appropriate physical property values and pulse parameters such as electrode spacing, size, and pulse amplitude. Complexities, such as heterogeneous tissues and changes in conductivity due to electroporation, are also discussed. The synthesis of these details can be used directly by surgeons in treatment planning. Irreversible electroporation is a promising new technique to treat cancer in a targeted manner without the use of drugs; however, it does require a detailed understanding of how electric currents flow within biological tissues. By providing the understanding and tools necessary to design an IRE protocol, this study seeks to facilitate the translation of this new and exciting cancer therapy into clinical practice.

@article{RN244,
   author = {Edd, J. F. and Horowitz, L. and Davalos, R. V. and Mir, L. M. and Rubinsky, B.},
   title = {In vivo results of a new focal tissue ablation technique: irreversible electroporation},
   journal = {IEEE Trans Biomed Eng},
   volume = {53},
   number = {7},
   pages = {1409-15},
   note = {Edd, Jon F
Horowitz, Liana
Davalos, Rafael V
Mir, Lluis M
Rubinsky, Boris
5R01RR1459/RR/NCRR NIH HHS/United States
Journal Article
Research Support, N.I.H., Extramural
United States
2006/07/13
IEEE Trans Biomed Eng. 2006 Jul;53(7):1409-15. doi: 10.1109/TBME.2006.873745.},
   abstract = {This paper reports results of in vivo experiments that confirm the feasibility of a new minimally invasive method for tissue ablation, irreversible electroporation (IRE). Electroporation is the generation of a destabilizing electric potential across biological membranes that causes the formation of nanoscale defects in the lipid bilayer. In IRE, these defects are permanent and lead to cell death. This paper builds on our earlier theoretical work and demonstrates that IRE can become an effective method for nonthermal tissue ablation requiring no drugs. To test the capability of IRE pulses to ablate tissue in a controlled fashion, we subjected the livers of male Sprague-Dawley rats to a single 20-ms-long square pulse of 1000 V/cm, which calculations had predicted would cause nonthermal IRE. Three hours after the pulse, treated areas in perfusion-fixed livers exhibited microvascular occlusion, endothelial cell necrosis, and diapedeses, resulting in ischemic damage to parenchyma and massive pooling of erythrocytes in sinusoids. However, large blood vessel architecture was preserved. Hepatocytes displayed blurred cell borders, pale eosinophilic cytoplasm, variable pyknosis and vacuolar degeneration. Mathematical analysis indicates that this damage was primarily nonthermal in nature and that sharp borders between affected and unaffected regions corresponded to electric fields of 300-500 V/cm.},
   keywords = {Animals
Catheter Ablation/*methods
Computer Simulation
Electroporation/*methods
Hepatectomy/*methods
Liver/*pathology/*surgery
Male
*Models, Biological
Rats
Rats, Sprague-Dawley
Treatment Outcome},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/tbme.2006.873745},
   year = {2006},
   type = {Journal Article}
}

This paper reports results of in vivo experiments that confirm the feasibility of a new minimally invasive method for tissue ablation, irreversible electroporation (IRE). Electroporation is the generation of a destabilizing electric potential across biological membranes that causes the formation of nanoscale defects in the lipid bilayer. In IRE, these defects are permanent and lead to cell death. This paper builds on our earlier theoretical work and demonstrates that IRE can become an effective method for nonthermal tissue ablation requiring no drugs. To test the capability of IRE pulses to ablate tissue in a controlled fashion, we subjected the livers of male Sprague-Dawley rats to a single 20-ms-long square pulse of 1000 V/cm, which calculations had predicted would cause nonthermal IRE. Three hours after the pulse, treated areas in perfusion-fixed livers exhibited microvascular occlusion, endothelial cell necrosis, and diapedeses, resulting in ischemic damage to parenchyma and massive pooling of erythrocytes in sinusoids. However, large blood vessel architecture was preserved. Hepatocytes displayed blurred cell borders, pale eosinophilic cytoplasm, variable pyknosis and vacuolar degeneration. Mathematical analysis indicates that this damage was primarily nonthermal in nature and that sharp borders between affected and unaffected regions corresponded to electric fields of 300-500 V/cm.

@article{RN245,
   author = {Lee, E. S. and Robinson, D. and Rognlien, J. L. and Harnett, C. K. and Simmons, B. A. and Bowe Ellis, C. R. and Davalos, R. V.},
   title = {Microfluidic electroporation of robust 10-microm vesicles for manipulation of picoliter volumes},
   journal = {Bioelectrochemistry},
   volume = {69},
   number = {1},
   pages = {117-25},
   note = {Lee, Eunice S
Robinson, David
Rognlien, Judith L
Harnett, Cindy K
Simmons, Blake A
Bowe Ellis, C R
Davalos, Rafael V
Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Netherlands
2006/02/18
Bioelectrochemistry. 2006 Sep;69(1):117-25. doi: 10.1016/j.bioelechem.2005.12.002. Epub 2006 Feb 17.},
   abstract = {We present a new way to transport and handle picoliter volumes of analytes in a microfluidic context through electrically monitored electroporation of 10-25 microm vesicles. In this method, giant vesicles are used to isolate analytes in a microfluidic environment. Once encapsulated inside a vesicle, contents will not diffuse and become diluted when exposed to pressure-driven flow. Two vesicle compositions have been developed that are robust enough to withstand electrical and mechanical manipulation in a microfluidic context. These vesicles can be guided and trapped, with controllable transfer of material into or out of their confined environment. Through electroporation, vesicles can serve as containers that can be opened when mixing and diffusion are desired, and closed during transport and analysis. Both vesicle compositions contain lecithin, an ethoxylated phospholipid, and a polyelectrolyte. Their performance is compared using a prototype microfluidic device and a simple circuit model. It was observed that the energy density threshold required to induce breakdown was statistically equivalent between compositions, 10.2+/-5.0 mJ/m2 for the first composition and 10.5+/-1.8 mJ/m2 for the second. This work demonstrates the feasibility of using giant, robust vesicles with microfluidic electroporation technology to manipulate picoliter volumes on-chip.},
   keywords = {Electroporation/*instrumentation/*methods
Lipids/chemistry
Microfluidics/*instrumentation/*methods
Models, Theoretical
Particle Size
Time Factors},
   ISSN = {1567-5394 (Print)
1567-5394},
   DOI = {10.1016/j.bioelechem.2005.12.002},
   year = {2006},
   type = {Journal Article}
}

We present a new way to transport and handle picoliter volumes of analytes in a microfluidic context through electrically monitored electroporation of 10-25 microm vesicles. In this method, giant vesicles are used to isolate analytes in a microfluidic environment. Once encapsulated inside a vesicle, contents will not diffuse and become diluted when exposed to pressure-driven flow. Two vesicle compositions have been developed that are robust enough to withstand electrical and mechanical manipulation in a microfluidic context. These vesicles can be guided and trapped, with controllable transfer of material into or out of their confined environment. Through electroporation, vesicles can serve as containers that can be opened when mixing and diffusion are desired, and closed during transport and analysis. Both vesicle compositions contain lecithin, an ethoxylated phospholipid, and a polyelectrolyte. Their performance is compared using a prototype microfluidic device and a simple circuit model. It was observed that the energy density threshold required to induce breakdown was statistically equivalent between compositions, 10.2+/-5.0 mJ/m2 for the first composition and 10.5+/-1.8 mJ/m2 for the second. This work demonstrates the feasibility of using giant, robust vesicles with microfluidic electroporation technology to manipulate picoliter volumes on-chip.

@article{ WOS:000227162700011,
Author = {Davalos, RV and Mir, LM and Rubinsky, B},
Title = {Tissue ablation with irreversible electroporation},
Journal = {ANNALS OF BIOMEDICAL ENGINEERING},
Year = {2005},
Volume = {33},
Number = {2},
Pages = {223-231},
Month = {FEB},
Abstract = {This study introduces a new method for minimally invasive treatment of
   cancer - the ablation of undesirable tissue through the use of
   irreversible electroporation. Electroporation is the permeabilization of
   the cell membrane due to an applied electric field. As a function of the
   field amplitude and duration, the permeabilization can be reversible or
   irreversible. Over the last decade, reversible electroporation has been
   intensively pursued as a very promising technique for the treatment of
   cancer. It is used in combination with cytotoxic drugs, such as
   bleomycin, in a technique known as electrochemotherapy. However,
   irreversible electroporation was completely ignored in cancer therapy.
   We show through mathematical analysis that irreversible electroporation
   can ablate substantial volumes of tissue, comparable to those achieved
   with other ablation techniques, without causing any detrimental thermal
   effects and without the need of adjuvant drugs. This study suggests that
   irreversible electroporation may become an important and innovative tool
   in the armamentarium of surgeons treating cancer.},
Publisher = {SPRINGER},
Address = {233 SPRING ST, NEW YORK, NY 10013 USA},
Type = {Article},
Language = {English},
Affiliation = {Davalos, RV (Corresponding Author), Sandia Natl Labs, 7011 East Ave,MS 9036, Livermore, CA 94550 USA.
   Sandia Natl Labs, Livermore, CA 94550 USA.
   Inst Gustave Roussy, CNRS, UMR 8121, Villejuif, France.
   Univ Calif Berkeley, Dept Mech Engn, Biomed Engn Lab, Berkeley, CA 94720 USA.},
DOI = {10.1007/s10439-005-8981-8},
ISSN = {0090-6964},
EISSN = {1573-9686},
Keywords = {electropermeabilization; cancer therapy; bioheat equation},
Keywords-Plus = {ELECTRICAL-IMPEDANCE TOMOGRAPHY; GENE DELIVERY; ELECTROCHEMOTHERAPY;
   MEMBRANES; BREAKDOWN; FIELDS; TUMORS; CELLS; CRYOSURGERY; BLEOMYCIN},
Research-Areas = {Engineering},
Web-of-Science-Categories  = {Engineering, Biomedical},
Author-Email = {rvdaval@sandia.gov},
Affiliations = {United States Department of Energy (DOE); Sandia National Laboratories;
   Centre National de la Recherche Scientifique (CNRS); UNICANCER; Gustave
   Roussy; University of California System; University of California
   Berkeley},
ResearcherID-Numbers = {yang, xiao-jun/B-1927-2009
   MIR, Lluis M/AAJ-9110-2020
   Rubinsky, Boris/B-4439-2010
   Davalos, Rafael V/F-9012-2011
   },
ORCID-Numbers = {, Lluis/0000-0002-8671-9467},
Funding-Acknowledgement = {NCRR NIH HHS {[}R01-RR018961] Funding Source: Medline},
Number-of-Cited-References = {44},
Times-Cited = {932},
Usage-Count-Last-180-days = {4},
Usage-Count-Since-2013 = {137},
Journal-ISO = {Ann. Biomed. Eng.},
Doc-Delivery-Number = {899RO},
Web-of-Science-Index = {Science Citation Index Expanded (SCI-EXPANDED)},
Unique-ID = {WOS:000227162700011},
DA = {2024-03-03},
}

This study introduces a new method for minimally invasive treatment of cancer - the ablation of undesirable tissue through the use of irreversible electroporation. Electroporation is the permeabilization of the cell membrane due to an applied electric field. As a function of the field amplitude and duration, the permeabilization can be reversible or irreversible. Over the last decade, reversible electroporation has been intensively pursued as a very promising technique for the treatment of cancer. It is used in combination with cytotoxic drugs, such as bleomycin, in a technique known as electrochemotherapy. However, irreversible electroporation was completely ignored in cancer therapy. We show through mathematical analysis that irreversible electroporation can ablate substantial volumes of tissue, comparable to those achieved with other ablation techniques, without causing any detrimental thermal effects and without the need of adjuvant drugs. This study suggests that irreversible electroporation may become an important and innovative tool in the armamentarium of surgeons treating cancer.

@article{RN246,
   author = {Lapizco-Encinas, B. H. and Davalos, R. V. and Simmons, B. A. and Cummings, E. B. and Fintschenko, Y.},
   title = {An insulator-based (electrodeless) dielectrophoretic concentrator for microbes in water},
   journal = {J Microbiol Methods},
   volume = {62},
   number = {3},
   pages = {317-26},
   note = {Lapizco-Encinas, Blanca H
Davalos, Rafael V
Simmons, Blake A
Cummings, Eric B
Fintschenko, Yolanda
Journal Article
Research Support, Non-U.S. Gov't
Netherlands
2005/06/09
J Microbiol Methods. 2005 Sep;62(3):317-26. doi: 10.1016/j.mimet.2005.04.027.},
   abstract = {Dielectrophoresis (DEP), the motion of a particle caused by an applied electric field gradient, can concentrate microorganisms non-destructively. In insulator-based dielectrophoresis (iDEP) insulating microstructures produce non-uniform electric fields to drive DEP in microsystems. This article describes the performance of an iDEP device in removing and concentrating bacterial cells, spores and viruses while operated with a DC applied electric field and pressure gradient. Such a device can selectively trap particles when dielectrophoresis overcomes electrokinesis or advection. The dielectrophoretic trapping behavior of labeled microorganisms in a glass-etched iDEP device was observed over a wide range of DC applied electric fields. When fields higher than a particle-specific threshold are applied, particles are reversibly trapped in the device. Experiments with Bacillus subtilis spores and the Tobacco Mosaic Virus (TMV) exhibited higher trapping thresholds than those of bacterial cells. The iDEP device was characterized in terms of concentration factor and removal efficiency. Under the experimental conditions used in this study with an initial dilution of 1 x 105 cells/ml, concentration factors of the order of 3000x and removal efficiencies approaching 100% were observed with Escherichia coli cells. These results are the first characterization of an iDEP device for the concentration and removal of microbes in water.},
   keywords = {Bacillus subtilis/isolation & purification
Electrophoresis/*instrumentation
Equipment Design
Escherichia coli/isolation & purification
Microbiological Techniques/*instrumentation
Microfluidic Analytical Techniques
Spores, Bacterial/isolation & purification
Tobacco Mosaic Virus/isolation & purification
*Water Microbiology},
   ISSN = {0167-7012 (Print)
0167-7012},
   DOI = {10.1016/j.mimet.2005.04.027},
   year = {2005},
   type = {Journal Article}
}

Dielectrophoresis (DEP), the motion of a particle caused by an applied electric field gradient, can concentrate microorganisms non-destructively. In insulator-based dielectrophoresis (iDEP) insulating microstructures produce non-uniform electric fields to drive DEP in microsystems. This article describes the performance of an iDEP device in removing and concentrating bacterial cells, spores and viruses while operated with a DC applied electric field and pressure gradient. Such a device can selectively trap particles when dielectrophoresis overcomes electrokinesis or advection. The dielectrophoretic trapping behavior of labeled microorganisms in a glass-etched iDEP device was observed over a wide range of DC applied electric fields. When fields higher than a particle-specific threshold are applied, particles are reversibly trapped in the device. Experiments with Bacillus subtilis spores and the Tobacco Mosaic Virus (TMV) exhibited higher trapping thresholds than those of bacterial cells. The iDEP device was characterized in terms of concentration factor and removal efficiency. Under the experimental conditions used in this study with an initial dilution of 1 x 105 cells/ml, concentration factors of the order of 3000x and removal efficiencies approaching 100% were observed with Escherichia coli cells. These results are the first characterization of an iDEP device for the concentration and removal of microbes in water.

@article{RN247,
   author = {Davalos, R. and Rubinsky, B.},
   title = {Electrical impedance tomography of cell viability in tissue with application to cryosurgery},
   journal = {J Biomech Eng},
   volume = {126},
   number = {2},
   pages = {305-9},
   note = {Davalos, Rafael
Rubinsky, Boris
5RO1 RR14591/RR/NCRR NIH HHS/United States
Comparative Study
Evaluation Study
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.
Validation Study
United States
2004/06/08
J Biomech Eng. 2004 Apr;126(2):305-9. doi: 10.1115/1.1695577.},
   abstract = {Tissue damage that is associated with the loss of cell membrane integrity should alter the bulk electrical properties of the tissue. This study shows that electrical impedance tomography (EIT) should be able to detect and image necrotic tissue inside the body due to the permeabilization of the membrane to ions. Cryosurgery, a minimally invasive surgical procedure that uses freezing to destroy undesirable tissue, was used to investigate the hypothesis. Experimental results with liver tissue demonstrate that cell damage during freezing results in substantial changes in tissue electrical properties. Two-dimensional EIT simulations of liver cryosurgery, which employ the experimental data, demonstrate the feasibility of this application.},
   keywords = {Animals
Cell Count/instrumentation/methods
Cell Survival
Cryosurgery/*adverse effects
Culture Techniques/instrumentation/methods
*Electric Impedance
Feasibility Studies
*Freezing
Liver/*pathology/physiopathology/*surgery
Liver Diseases/*etiology/*pathology/physiopathology
Rats
Rats, Sprague-Dawley
Tomography/instrumentation/*methods},
   ISSN = {0148-0731 (Print)
0148-0731},
   DOI = {10.1115/1.1695577},
   year = {2004},
   type = {Journal Article}
}

Tissue damage that is associated with the loss of cell membrane integrity should alter the bulk electrical properties of the tissue. This study shows that electrical impedance tomography (EIT) should be able to detect and image necrotic tissue inside the body due to the permeabilization of the membrane to ions. Cryosurgery, a minimally invasive surgical procedure that uses freezing to destroy undesirable tissue, was used to investigate the hypothesis. Experimental results with liver tissue demonstrate that cell damage during freezing results in substantial changes in tissue electrical properties. Two-dimensional EIT simulations of liver cryosurgery, which employ the experimental data, demonstrate the feasibility of this application.

@article{RN248,
   author = {Davalos, R. V. and Otten, D. M. and Mir, L. M. and Rubinsky, B.},
   title = {Electrical impedance tomography for imaging tissue electroporation},
   journal = {IEEE Trans Biomed Eng},
   volume = {51},
   number = {5},
   pages = {761-7},
   note = {Davalos, Rafael V
Otten, David M
Mir, Lluis M
Rubinsky, Boris
1 R21 RR15252-01/RR/NCRR NIH HHS/United States
Evaluation Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Validation Study
United States
2004/05/11
IEEE Trans Biomed Eng. 2004 May;51(5):761-7. doi: 10.1109/TBME.2004.824148.},
   abstract = {Electroporation is a method to introduce molecules, such as gene constructs or small drugs, into cells by temporarily permeating the cell membrane with electric pulses. In molecular medicine and biotechnology, tissue electroporation is performed with electrodes placed in the target area of the body. Currently, tissue electroporation, as with all other methods of molecular medicine, is performed without real-time control or near-term information regarding the extent and degree of electroporation. This paper expands the work from our previous study by implementing new ex vivo experimental data with "front-tracking" analysis for the image reconstruction algorithm. The experimental data is incorporated into numerical simulations of electroporation procedures and images are generated using the new reconstruction algorithm to demonstrate that electrical impedance tomography (EIT) can produce an image of the electroporated area. Combining EIT with electroporation could become an important biotechnological and medical technique to introduce therapeutic molecules into cells in tissue at predetermined areas of the body.},
   keywords = {*Algorithms
Animals
Cell Membrane Permeability/*physiology
Connective Tissue/metabolism/ultrastructure
Culture Techniques
Diagnosis, Computer-Assisted/methods
*Electric Impedance
Image Enhancement/*methods
Image Interpretation, Computer-Assisted/*methods
Liver/*cytology/*physiology
Male
Rats
Tomography/instrumentation/*methods},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/tbme.2004.824148},
   year = {2004},
   type = {Journal Article}
}

Electroporation is a method to introduce molecules, such as gene constructs or small drugs, into cells by temporarily permeating the cell membrane with electric pulses. In molecular medicine and biotechnology, tissue electroporation is performed with electrodes placed in the target area of the body. Currently, tissue electroporation, as with all other methods of molecular medicine, is performed without real-time control or near-term information regarding the extent and degree of electroporation. This paper expands the work from our previous study by implementing new ex vivo experimental data with "front-tracking" analysis for the image reconstruction algorithm. The experimental data is incorporated into numerical simulations of electroporation procedures and images are generated using the new reconstruction algorithm to demonstrate that electrical impedance tomography (EIT) can produce an image of the electroporated area. Combining EIT with electroporation could become an important biotechnological and medical technique to introduce therapeutic molecules into cells in tissue at predetermined areas of the body.

@article{RN249,
   author = {Davalos, R. V. and Rubinsky, B. and Mir, L. M.},
   title = {Theoretical analysis of the thermal effects during in vivo tissue electroporation},
   journal = {Bioelectrochemistry},
   volume = {61},
   number = {1-2},
   pages = {99-107},
   note = {Davalos, Rafael V
Rubinsky, Boris
Mir, Lluis M
1 R21 RR15252-01/RR/NCRR NIH HHS/United States
Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.
Netherlands
2003/12/04
Bioelectrochemistry. 2003 Oct;61(1-2):99-107. doi: 10.1016/j.bioelechem.2003.07.001.},
   abstract = {Tissue electroporation is a technique that facilitates the introduction of molecules into cells by applying a series of short electric pulses to specific areas of the body. These pulses temporarily increase the permeability of the cell membrane to small drugs and macromolecules. The goal of this paper is to provide information on the thermal effects of these electric pulses for consideration when designing electroporation protocols. The parameters investigated include electrode geometry, blood flow, metabolic heat generation, pulse frequency, and heat dissipation through the electrodes. Basic finite-element models were created in order to gain insight and weigh the importance of each parameter. The results suggest that for plate electrodes, the energy from the pulse may be used to adequately estimate the heating in the tissue. However, for needle electrodes, the geometry, i.e. spacing and diameter, and pulse frequency are critical when determining the thermal distribution in the tissue.},
   keywords = {Animals
Electrodes
*Electroporation
*Hot Temperature
Liver/physiology
*Models, Biological
Muscles/*physiology
Rats
Regional Blood Flow
Thermal Conductivity
Time Factors},
   ISSN = {1567-5394 (Print)
1567-5394},
   DOI = {10.1016/j.bioelechem.2003.07.001},
   year = {2003},
   type = {Journal Article}
}

Tissue electroporation is a technique that facilitates the introduction of molecules into cells by applying a series of short electric pulses to specific areas of the body. These pulses temporarily increase the permeability of the cell membrane to small drugs and macromolecules. The goal of this paper is to provide information on the thermal effects of these electric pulses for consideration when designing electroporation protocols. The parameters investigated include electrode geometry, blood flow, metabolic heat generation, pulse frequency, and heat dissipation through the electrodes. Basic finite-element models were created in order to gain insight and weigh the importance of each parameter. The results suggest that for plate electrodes, the energy from the pulse may be used to adequately estimate the heating in the tissue. However, for needle electrodes, the geometry, i.e. spacing and diameter, and pulse frequency are critical when determining the thermal distribution in the tissue.

@article{RN250,
   author = {Davalos, R. V. and Rubinsky, B. and Otten, D. M.},
   title = {A feasibility study for electrical impedance tomography as a means to monitor tissue electroporation for molecular medicine},
   journal = {IEEE Trans Biomed Eng},
   volume = {49},
   number = {4},
   pages = {400-3},
   note = {Davalos, Rafael V
Rubinsky, Boris
Otten, David M
1 R21 RR15252-01/RR/NCRR NIH HHS/United States
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
United States
2002/04/11
IEEE Trans Biomed Eng. 2002 Apr;49(4):400-3. doi: 10.1109/10.991168.},
   abstract = {Molecular medicine involves the introduction of macromolecules, such as drugs or gene constructs, into specific cells of the body. Electroporation, which uses electric pulses to permeate cell membranes, is a method for achieving this. However, as with other molecular medicine procedures, it lacks a real-time mechanism to detect and control which cells have been affected. We propose and demonstrate, via computer simulation, that electrical impedance tomography has the potential for detecting and imaging electroporation of cells in tissue in real-time, thereby providing feedback for controlling electroporation.},
   keywords = {Computer Simulation
Electric Impedance
Electroporation/*methods
Feasibility Studies
Macromolecular Substances
Molecular Biology
Tomography/*methods},
   ISSN = {0018-9294 (Print)
0018-9294},
   DOI = {10.1109/10.991168},
   year = {2002},
   type = {Journal Article}
}

Molecular medicine involves the introduction of macromolecules, such as drugs or gene constructs, into specific cells of the body. Electroporation, which uses electric pulses to permeate cell membranes, is a method for achieving this. However, as with other molecular medicine procedures, it lacks a real-time mechanism to detect and control which cells have been affected. We propose and demonstrate, via computer simulation, that electrical impedance tomography has the potential for detecting and imaging electroporation of cells in tissue in real-time, thereby providing feedback for controlling electroporation.