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Chole AM, Duffy M. Piezoelectric Transformer-Based High-Voltage Pulse Generator Using Wide-Bandgap Semiconductors for Medical Electroporation Therapy. Ann Biomed Eng 2024; 52:36-47. [PMID: 37468687 PMCID: PMC10761399 DOI: 10.1007/s10439-023-03319-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/11/2023] [Indexed: 07/21/2023]
Abstract
In this paper, a new application of Piezoelectric Transformer (PT)-based power converters to generate high-voltage (HV) bipolar pulses for medical electroporation therapy is proposed. In particular, PT-based power conversion is investigated as an alternative to magnetics-based approaches of generating HV from a relatively low-voltage (LV) input source for application in electroporation therapy. The detailed PT-based system design and selection of wide bandgap semiconductor switches such as GaN FETs, high-voltage SiC diodes and SiC MOSFETs, as well as simulation results to demonstrate proof-of-concept using LTSpice are presented. Preliminary experimental results of the PT-based capacitor charger are shown, and work is ongoing to develop a complete hardware prototype of the proposed HV pulse generator.
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Affiliation(s)
- Ajay M Chole
- Power Electronics Research Centre, University of Galway, Galway, H91 HX31, Ireland.
| | - Maeve Duffy
- Power Electronics Research Centre, University of Galway, Galway, H91 HX31, Ireland
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2
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Sugrue A, Maor E, Del-Carpio Munoz F, Killu AM, Asirvatham SJ. Cardiac ablation with pulsed electric fields: principles and biophysics. Europace 2022; 24:1213-1222. [PMID: 35426908 DOI: 10.1093/europace/euac033] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/24/2022] [Indexed: 01/04/2023] Open
Abstract
Pulsed electric fields (PEFs) have emerged as an ideal cardiac ablation modality. At present numerous clinical trials in humans are exploring PEF as an ablation strategy for both atrial and ventricular arrhythmias, with early data showing significant promise. As this is a relatively new technology there is limited understanding of its principles and biophysics. Importantly, PEF biophysics and principles are starkly different to current energy modalities (radiofrequency and cryoballoon). Given the relatively novel nature of PEFs, this review aims to provide an understanding of the principles and biophysics of PEF ablation. The goal is to enhance academic research and ultimately enable optimization of ablation parameters to maximize procedure success and minimize risk.
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Affiliation(s)
- Alan Sugrue
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Elad Maor
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- Chaim Sheba Medical Center and Sackler School of Medicine, Tel Aviv University, Israel
| | - Freddy Del-Carpio Munoz
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Ammar M Killu
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Samuel J Asirvatham
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
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Electroporation and Electrochemotherapy in Gynecological and Breast Cancer Treatment. Molecules 2022; 27:molecules27082476. [PMID: 35458673 PMCID: PMC9026735 DOI: 10.3390/molecules27082476] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 03/14/2022] [Accepted: 04/10/2022] [Indexed: 12/24/2022] Open
Abstract
Gynecological carcinomas affect an increasing number of women and are associated with poor prognosis. The gold standard treatment plan is mainly based on surgical resection and subsequent chemotherapy with cisplatin, 5-fluorouracil, anthracyclines, or taxanes. Unfortunately, this treatment is becoming less effective and is associated with many side effects that negatively affect patients’ physical and mental well-being. Electroporation based on tumor exposure to electric pulses enables reduction in cytotoxic drugs dose while increasing their effectiveness. EP-based treatment methods have received more and more interest in recent years and are the subject of a large number of scientific studies. Some of them show promising therapeutic potential without using any cytotoxic drugs or molecules already present in the human body (e.g., calcium electroporation). This literature review aims to present the fundamental mechanisms responsible for the course of EP-based therapies and the current state of knowledge in the field of their application in the treatment of gynecological neoplasms.
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Sachdev S, Potočnik T, Rems L, Miklavčič D. Revisiting the role of pulsed electric fields in overcoming the barriers to in vivo gene electrotransfer. Bioelectrochemistry 2022; 144:107994. [PMID: 34930678 DOI: 10.1016/j.bioelechem.2021.107994] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/15/2021] [Accepted: 11/02/2021] [Indexed: 12/21/2022]
Abstract
Gene therapies are revolutionizing medicine by providing a way to cure hitherto incurable diseases. The scientific and technological advances have enabled the first gene therapies to become clinically approved. In addition, with the ongoing COVID-19 pandemic, we are witnessing record speeds in the development and distribution of gene-based vaccines. For gene therapy to take effect, the therapeutic nucleic acids (RNA or DNA) need to overcome several barriers before they can execute their function of producing a protein or silencing a defective or overexpressing gene. This includes the barriers of the interstitium, the cell membrane, the cytoplasmic barriers and (in case of DNA) the nuclear envelope. Gene electrotransfer (GET), i.e., transfection by means of pulsed electric fields, is a non-viral technique that can overcome these barriers in a safe and effective manner. GET has reached the clinical stage of investigations where it is currently being evaluated for its therapeutic benefits across a wide variety of indications. In this review, we formalize our current understanding of GET from a biophysical perspective and critically discuss the mechanisms by which electric field can aid in overcoming the barriers. We also identify the gaps in knowledge that are hindering optimization of GET in vivo.
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Affiliation(s)
- Shaurya Sachdev
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Tjaša Potočnik
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Lea Rems
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia.
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Chauhan M, Sadleir R. MR Current Density and MREIT Data Acquisition. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1380:111-134. [DOI: 10.1007/978-3-031-03873-0_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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6
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Scratching the electrode surface: Insights into a high-voltage pulsed-field application from in vitro & in silico studies in indifferent fluid. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.137187] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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7
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A numerical study on the effect of conductivity change in cell kill distribution in irreversible electroporation. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2020. [DOI: 10.2478/pjmpe-2020-0008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Abstract
Introduction: irreversible electroporation (IRE) is a tissue ablation technique and physical process used to kill the undesirable cells. In the IRE process by mathematical modelling we can calculate the cell kill probability and distribution inside the tissue. The purpose of the study is to determine the influence of electric conductivity change in the IRE process into the cell kill probability and distribution.
Methods: cell death probability and electric conductivity were calculated with COMSOL Multiphysics software package. 8 pulses with a frequency of 1 Hz, pulse width of 100 µs and electric field intensity from 1000 to 3000 V/Cm with steps of 500 V/Cm used as electric pulses.
Results: significantly, the electrical conductivity of tissue will increase during the time of pulse delivery. According to our results, electrical conductivity increased with an electric field intensity of pulses. By considering the effect of conductivity change on cell kill probability, the cell kill probability and distribution will change.
Conclusion: we believe that considering the impact of electric conductivity change on the cell kill probability will improve the accuracy of treatment outcome in the clinic for treatment with IRE.
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Electronic Emulator of Biological Tissue as an Electrical Load during Electroporation. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10093103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Electroporation is an emerging technology, with great potential in many different medical and biotechnological applications, food engineering and biomass processing. Large variations of biological load characteristics, however, represent a great challenge in electroporator design, which results in different solutions. Because a clinical electroporator is a medical device, it must comply with medical device regulative and standards. However, none of the existing standards directly address the operation or electroporator’s performance requirements. In order to evaluate clinical, laboratory and prototype electroporation devices during the development process, or to evaluate their final performance considering at least from the perspective of output pulse parameters, we present a case study on the design of an electronic emulator of biological tissue as an electrical load during electroporation. The proposed electronic load emulator is a proof of concept, which enables constant and sustainable testing and unbiased comparison of different electroporators’ operations. We developed an analog electrical circuit that has equivalent impedance to the beef liver tissue in combination with needle electrodes, during high voltage pulse delivery and/or electroporation. Current and voltage measurements during electroporation of beef liver tissue ex vivo, were analyzed and parametrized to define the analog circuit equation. An equivalent circuit was simulated, built and validated. The proposed concept of an electronic load emulator can be used for “classical” electroporator (i.e., not nanosecond) performance evaluation and comparison of their operation. Additionally, it facilitates standard implementation regarding the testing protocol and enables quality assurance.
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Ozyigit II. Gene transfer to plants by electroporation: methods and applications. Mol Biol Rep 2020; 47:3195-3210. [PMID: 32242300 DOI: 10.1007/s11033-020-05343-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/22/2020] [Indexed: 01/09/2023]
Abstract
Developing gene transfer technologies enables the genetic manipulation of the living organisms more efficiently. The methods used for gene transfer fall into two main categories; natural and artificial transformation. The natural methods include the conjugation, transposition, bacterial transformation as well as phage and retroviral transductions, contain the physical methods whereas the artificial methods can physically alter and transfer genes from one to another organisms' cell using, for instance, biolistic transformation, micro- and macroinjection, and protoplast fusion etc. The artificial gene transformation can also be conducted through chemical methods which include calcium phosphate-mediated, polyethylene glycol-mediated, DEAE-Dextran, and liposome-mediated transfers. Electrical methods are also artificial ways to transfer genes that can be done by electroporation and electrofusion. Comparatively, among all the above-mentioned methods, electroporation is being widely used owing to its high efficiency and broader applicability. Electroporation is an electrical transformation method by which transient electropores are produced in the cell membranes. Based on the applications, process can be either reversible where electropores in membrane are resealable and cells preserve the vitality or irreversible where membrane is not able to reseal, and cell eventually dies. This problem can be minimized by developing numerical models to iteratively optimize the field homogeneity considering the cell size, shape, number, and electrode positions supplemented by real-time measurements. In modern biotechnology, numerical methods have been used in electrotransformation, electroporation-based inactivation, electroextraction, and electroporative biomass drying. Moreover, current applications of electroporation also point to some other uncovered potentials for various exploitations in future.
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Affiliation(s)
- Ibrahim Ilker Ozyigit
- Department of Biology, Faculty of Science and Arts, Marmara University, Goztepe, 34722, Istanbul, Turkey. .,Department of Biology, Faculty of Science, Kyrgyz-Turkish Manas University, 720038, Bishkek, Kyrgyzstan.
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Conductivity change with needle electrode during high frequency irreversible electroporation: a finite element study. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2019. [DOI: 10.2478/pjmpe-2019-0031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Irreversible electroporation (IRE) is a process in which the cell membrane is damaged and leads to cell death. IRE has been used as a minimally invasive ablation tool. This process is affected by some factors. The most important factor is the electric field distribution inside the tissue. The electric field distribution depends on the electric pulse parameters and tissue properties, such as the electrical conductivity of tissue. The present study focuses on evaluating the tissue conductivity change due to high-frequency and low-voltage (HFLV) as well as low-frequency and high-voltage (LFHV) pulses during irreversible electroporation. We were used finite element analysis software, COMSOL Multiphysics 5.0, to calculate the conductivity change of the liver tissue. The HFLV pulses in this study involved 4000 bipolar and monopolar pulses with a frequency of 5 kHz, pulse width of 100 µs, and electric field intensity from 100 to 300 V/cm. On the other hand, the LFHV pulses, which we were used, included 8 bipolar and monopolar pulses with a frequency of 1 Hz, the pulse width of 2 ms and electric field intensity of 2500 V/cm. The results demonstrate that the conductivity change for LFHV pulses due to the greater electric field intensity was higher than for HFLV pulses. The most significant conclusion is the HFLV pulses can change tissue conductivity only in the vicinity of the tip of electrodes. While LFHV pulses change the electrical conductivity significantly in the tissue of between electrodes.
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11
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Dermol-Cerne J, Miklavcic D. From Cell to Tissue Properties-Modeling Skin Electroporation With Pore and Local Transport Region Formation. IEEE Trans Biomed Eng 2019; 65:458-468. [PMID: 29364121 DOI: 10.1109/tbme.2017.2773126] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Current models of tissue electroporation either describe tissue with its bulk properties or include cell level properties, but model only a few cells of simple shapes in low-volume fractions or are in two dimensions. We constructed a three-dimensional model of realistically shaped cells in realistic volume fractions. By using a 'unit cell' model, the equivalent dielectric properties of whole tissue could be calculated. We calculated the dielectric properties of electroporated skin. We modeled electroporation of single cells by pore formation on keratinocytes and on the papillary dermis which gave dielectric properties of the electroporated epidermis and papillary dermis. During skin electroporation, local transport regions are formed in the stratum corneum. We modeled local transport regions and increase in their radii or density which affected the dielectric properties of the stratum corneum. The final model of skin electroporation accurately describes measured electric current and voltage drop on the skin during electroporation with long low-voltage pulses. The model also accurately describes voltage drop on the skin during electroporation with short high-voltage pulses. However, our results indicate that during application of short high-voltage pulses additional processes may occur which increase the electric current. Our model connects the processes occurring at the level of cell membranes (pore formation), at the level of a skin layer (formation of local transport region in the stratum corneum) with the tissue (skin layers) and even level of organs (skin). Using a similar approach, electroporation of any tissue can be modeled, if the morphology of the tissue is known.
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12
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Zhao Y, Liu H, Bhonsle SP, Wang Y, Davalos RV, Yao C. Ablation outcome of irreversible electroporation on potato monitored by impedance spectrum under multi-electrode system. Biomed Eng Online 2018; 17:126. [PMID: 30236121 PMCID: PMC6148960 DOI: 10.1186/s12938-018-0562-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Accepted: 09/17/2018] [Indexed: 11/10/2022] Open
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.
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Affiliation(s)
- Yajun Zhao
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, School of Electrical Engineering, Chongqing University, No. 174 Shazhengjie, Shapingba District, Chongqing, 400044, China.,Department of Biomedical Engineering and Mechanics, Virginia Tech, 329 ICTAS Stanger St (0298), Blacksburg, VA, 24061, USA
| | - Hongmei Liu
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, School of Electrical Engineering, Chongqing University, No. 174 Shazhengjie, Shapingba District, Chongqing, 400044, China
| | - Suyashree P Bhonsle
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 329 ICTAS Stanger St (0298), Blacksburg, VA, 24061, USA
| | - Yilin Wang
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, School of Electrical Engineering, Chongqing University, No. 174 Shazhengjie, Shapingba District, Chongqing, 400044, China
| | - Rafael V Davalos
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 329 ICTAS Stanger St (0298), Blacksburg, VA, 24061, USA.
| | - Chenguo Yao
- State Key Laboratory of Power Transmission Equipment and System Security and New Technology, School of Electrical Engineering, Chongqing University, No. 174 Shazhengjie, Shapingba District, Chongqing, 400044, China.
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Batista Napotnik T, Miklavčič D. In vitro electroporation detection methods – An overview. Bioelectrochemistry 2018; 120:166-182. [DOI: 10.1016/j.bioelechem.2017.12.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/11/2017] [Accepted: 12/11/2017] [Indexed: 12/22/2022]
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Predicting irreversible electroporation-induced tissue damage by means of magnetic resonance electrical impedance tomography. Sci Rep 2017; 7:10323. [PMID: 28871138 PMCID: PMC5583379 DOI: 10.1038/s41598-017-10846-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/15/2017] [Indexed: 02/07/2023] Open
Abstract
Irreversible electroporation (IRE) is gaining importance in routine clinical practice for nonthermal ablation of solid tumors. For its success, it is extremely important that the coverage and exposure time of the treated tumor to the electric field is within the specified range. Measurement of electric field distribution during the electroporation treatment can be achieved using magnetic resonance electrical impedance tomography (MREIT). Here, we show improved MREIT-enabled electroporation monitoring of IRE-treated tumors by predicting IRE-ablated tumor areas during IRE of mouse tumors in vivo. The in situ prediction is enabled by coupling MREIT with a corresponding Peleg-Fermi mathematical model to obtain more informative monitoring of IRE tissue ablation by providing cell death probability in the IRE-treated tumors. This technique can potentially be used in electroporation-based clinical applications, such as IRE tissue ablation and electrochemotherapy, to improve and assure the desired treatment outcome.
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15
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Electric field distribution in relation to cell membrane electroporation in potato tuber tissue studied by magnetic resonance techniques. INNOV FOOD SCI EMERG 2016. [DOI: 10.1016/j.ifset.2016.03.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chafai DE, Mehle A, Tilmatine A, Maouche B, Miklavčič D. Assessment of the electrochemical effects of pulsed electric fields in a biological cell suspension. Bioelectrochemistry 2015; 106:249-57. [DOI: 10.1016/j.bioelechem.2015.08.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 08/10/2015] [Accepted: 08/10/2015] [Indexed: 11/25/2022]
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Bonakdar M, Latouche EL, Mahajan RL, Davalos RV. The Feasibility of a Smart Surgical Probe for Verification of IRE Treatments Using Electrical Impedance Spectroscopy. IEEE Trans Biomed Eng 2015; 62:2674-84. [PMID: 26057529 DOI: 10.1109/tbme.2015.2441636] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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.
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Current density imaging sequence for monitoring current distribution during delivery of electric pulses in irreversible electroporation. Biomed Eng Online 2015; 14 Suppl 3:S6. [PMID: 26356233 PMCID: PMC4565567 DOI: 10.1186/1475-925x-14-s3-s6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background Electroporation is gaining its importance in everyday clinical practice of cancer treatment. For its success it is extremely important that coverage of the target tissue, i.e. treated tumor, with electric field is within the specified range. Therefore, an efficient tool for the electric field monitoring in the tumor during delivery of electroporation pulses is needed. The electric field can be reconstructed by the magnetic resonance electric impedance tomography method from current density distribution data. In this study, the use of current density imaging with MRI for monitoring current density distribution during delivery of irreversible electroporation pulses was demonstrated. Methods Using a modified single-shot RARE sequence, where four 3000 V and 100 μs long pulses were included at the start, current distribution between a pair of electrodes inserted in a liver tissue sample was imaged. Two repetitions of the sequence with phases of refocusing radiofrequency pulses 90° apart were needed to acquire one current density image. For each sample in total 45 current density images were acquired to follow a standard protocol for irreversible electroporation where 90 electric pulses are delivered at 1 Hz. Results Acquired current density images showed that the current density in the middle of the sample increased from first to last electric pulses by 60%, i.e. from 8 kA/m2 to 13 kA/m2 and that direction of the current path did not change with repeated electric pulses significantly. Conclusions The presented single-shot RARE-based current density imaging sequence was used successfully to image current distribution during delivery of short high-voltage electric pulses. The method has a potential to enable monitoring of tumor coverage by electric field during irreversible electroporation tissue ablation.
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Dermol J, Miklavčič D. Mathematical Models Describing Chinese Hamster Ovary Cell Death Due to Electroporation In Vitro. J Membr Biol 2015. [PMID: 26223863 DOI: 10.1007/s00232-015-9825-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Electroporation is a phenomenon used in the treatment of tumors by electrochemotherapy, non-thermal ablation with irreversible electroporation, and gene therapy. When treating patients, either predefined or variable electrode geometry is used. Optimal pulse parameters are predetermined for predefined electrode geometry, while they must be calculated for each specific case for variable electrode geometry. The position and number of electrodes are also determined for each patient. It is currently assumed that above a certain experimentally determined value of electric field, all cells are permeabilized/destroyed and under it they are unaffected. In this paper, mathematical models of survival in which the probability of cell death is continuously distributed from 0 to 100 % are proposed and evaluated. Experiments were performed on cell suspensions using electrical parameters similar to standard electrochemotherapy and irreversible electroporation parameters. The proportion of surviving cells was determined using clonogenic assay for assessing the ability of a cell to grow into a colony. Various mathematical models (first-order kinetics, Hülsheger, Peleg-Fermi, Weibull, logistic, adapted Gompertz, Geeraerd) were fitted to experimental data using a non-linear least-squares method. The fit was evaluated by calculating goodness of fit and by observing the trend of values of models' parameters. The most appropriate models of cell survival as a function of treatment time were the adapted Gompertz and the Geeraerd models and, as a function of the electric field, the logistic, adapted Gompertz and Peleg-Fermi models. The next steps to be performed are validation of the most appropriate models on tissues and determination of the models' predictive power.
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Affiliation(s)
- Janja Dermol
- Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, 1000, Ljubljana, Slovenia
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Kotnik T, Frey W, Sack M, Haberl Meglič S, Peterka M, Miklavčič D. Electroporation-based applications in biotechnology. Trends Biotechnol 2015; 33:480-8. [PMID: 26116227 DOI: 10.1016/j.tibtech.2015.06.002] [Citation(s) in RCA: 283] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/22/2015] [Accepted: 06/01/2015] [Indexed: 02/06/2023]
Abstract
Electroporation is already an established technique in several areas of medicine, but many of its biotechnological applications have only started to emerge; we review here some of the most promising. We outline electroporation as a phenomenon and then proceed to applications, first outlining the best established - the use of reversible electroporation for heritable genetic modification of microorganisms (electrotransformation), and then explore recent advances in applying electroporation for inactivation of microorganisms, extraction of biomolecules, and fast drying of biomass. Although these applications often aim to upscale to the industrial and/or clinical level, we also outline some important chip-scale applications of electroporation. We conclude our review with a discussion of the main challenges and future perspectives.
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Affiliation(s)
- Tadej Kotnik
- Department of Biomedical Engineering, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, 1000 Ljubljana, Slovenia
| | - Wolfgang Frey
- Institute for Pulsed Power and Microwave Technology, Karlsruhe Institute of Technology, Hermann-v-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Martin Sack
- Institute for Pulsed Power and Microwave Technology, Karlsruhe Institute of Technology, Hermann-v-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Saša Haberl Meglič
- Department of Biomedical Engineering, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, 1000 Ljubljana, Slovenia
| | - Matjaž Peterka
- Instrumentation and Process Control, Centre of Excellence for Biosensors, Tovarniška cesta 26, 5270 Ajdovščina, Slovenia
| | - Damijan Miklavčič
- Department of Biomedical Engineering, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, 1000 Ljubljana, Slovenia.
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Suárez C, Soba A, Maglietti F, Olaiz N, Marshall G. The role of additional pulses in electropermeabilization protocols. PLoS One 2014; 9:e113413. [PMID: 25437512 PMCID: PMC4249911 DOI: 10.1371/journal.pone.0113413] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 10/23/2014] [Indexed: 12/21/2022] Open
Abstract
Electropermeabilization (EP) based protocols such as those applied in medicine, food processing or environmental management, are well established and widely used. The applied voltage, as well as tissue electric conductivity, are of utmost importance for assessing final electropermeabilized area and thus EP effectiveness. Experimental results from literature report that, under certain EP protocols, consecutive pulses increase tissue electric conductivity and even the permeabilization amount. Here we introduce a theoretical model that takes into account this effect in the application of an EP-based protocol, and its validation with experimental measurements. The theoretical model describes the electric field distribution by a nonlinear Laplace equation with a variable conductivity coefficient depending on the electric field, the temperature and the quantity of pulses, and the Penne's Bioheat equation for temperature variations. In the experiments, a vegetable tissue model (potato slice) is used for measuring electric currents and tissue electropermeabilized area in different EP protocols. Experimental measurements show that, during sequential pulses and keeping constant the applied voltage, the electric current density and the blackened (electropermeabilized) area increase. This behavior can only be attributed to a rise in the electric conductivity due to a higher number of pulses. Accordingly, we present a theoretical modeling of an EP protocol that predicts correctly the increment in the electric current density observed experimentally during the addition of pulses. The model also demonstrates that the electric current increase is due to a rise in the electric conductivity, in turn induced by temperature and pulse number, with no significant changes in the electric field distribution. The EP model introduced, based on a novel formulation of the electric conductivity, leads to a more realistic description of the EP phenomenon, hopefully providing more accurate predictions of treatment outcomes.
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Affiliation(s)
- Cecilia Suárez
- Laboratorio de Sistemas Complejos, Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandro Soba
- Centro de Simulación Computacional - CONICET y Comisión Nacional de Energia Atómica, Buenos Aires, Argentina
| | - Felipe Maglietti
- Laboratorio de Sistemas Complejos, Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Nahuel Olaiz
- Laboratorio de Sistemas Complejos, Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Guillermo Marshall
- Laboratorio de Sistemas Complejos, Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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