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Silkunas M, Silkuniene G, Pakhomov AG. Real-time imaging of individual electropores proves their longevity in cells. Biochem Biophys Res Commun 2024; 695:149408. [PMID: 38157631 PMCID: PMC10842338 DOI: 10.1016/j.bbrc.2023.149408] [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: 12/16/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024]
Abstract
With over 50 years of electroporation research, the nature of cell membrane permeabilization remains elusive. The lifetime of electropores in molecular models is limited to nano- or microseconds, whereas the permeabilization of electroporated cells can last minutes. This study aimed at resolving a longstanding debate on whether the prolonged permeabilization is due to the formation of long-lived pores in cells. We developed a method for dynamic monitoring and conductance measurements of individual electropores. This was accomplished by time-lapse total internal reflection fluorescence (TIRF) imaging in HEK cells loaded with CAL-520 dye and placed on an indium tin oxide (ITO) surface. Applying a 1-ms, 0 to -400 mV pulse between the patch pipette and ITO evoked focal Ca2+ transients that identified individual electropores. Some transients disappeared in milliseconds but others persisted for over a minute. Persistent transients ("Ca2+ plumes") faded over time to a stable or a randomly fluctuating level that could include periods of full quiescence. Single pore conductance, measured by 0 to -50 mV, 50 ms steps at 30 and 60 s after the electroporation, ranged from 80 to 200 pS. These experiments proved electropore longevity in cells, in stark contrast to molecular simulations and many findings in lipid bilayers.
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Affiliation(s)
- Mantas Silkunas
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA; Institute for Digestive System Research, Lithuanian University of Health Sciences, 44307, Kaunas, Lithuania
| | - Giedre Silkuniene
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA; Institute for Digestive System Research, Lithuanian University of Health Sciences, 44307, Kaunas, Lithuania
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.
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Huang C, Han SI, Zhang H, Han A. Tutorial on Lateral Dielectrophoretic Manipulations in Microfluidic Systems. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2023; 17:21-32. [PMID: 37015136 PMCID: PMC10091972 DOI: 10.1109/tbcas.2022.3226675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Microfluidic lab-on-a-chip systems can offer cost- and time-efficient biological assays by providing high-throughput analysis at very small volume scale. Among these extremely broad ranges of assays, accurate and specific cell and reagent control is considered one of the most important functions. Dielectrophoretic (DEP)-based manipulation technologies have been extensively developed for these purposes due to their label-free and high selectivity natures as well as due to their simple microstructures. Here, we provide a tutorial on how to develop DEP-based microfluidic systems, including a detailed walkthrough of dielectrophoresis theory, instruction on how to conduct simulation and calculation of electric field and generated DEP force, followed with guidance on microfabricating two forms of DEP microfluidic systems, namely lateral DEP and droplet DEP, and how best to conduct experiments in such systems. Finally, we summarize most recent DEP-based microfluidic technologies and applications, including systems for blood diagnoses, pathogenicity studies, in-droplet content manipulations, droplet manipulations and merging, to name a few. We conclude by suggesting possible future directions on how DEP-based technologies can be utilized to overcome current challenges and improve the current status in microfluidic lab-on-a-chip systems.
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Young CC, Byrne JD, Wentworth AJ, Collins JE, Chu JN, Traverso G. Respirators in Healthcare: Material, Design, Regulatory, Environmental, and Economic Considerations for Clinical Efficacy. GLOBAL CHALLENGES (HOBOKEN, NJ) 2022; 6:2200001. [PMID: 35601599 PMCID: PMC9110919 DOI: 10.1002/gch2.202200001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Indexed: 06/15/2023]
Abstract
Maintaining an ample supply of personal protective equipment continues to be a challenge for the healthcare industry, especially during emergency situations and times of strain on the supply chain. Most critically, healthcare workers exposed to potential airborne hazards require sufficient respiratory protection. Respirators are the only type of personal protective equipment able to provide adequate respiratory protection. However, their ability to shield hazards depends on design, material, proper fit, and environmental conditions. As a result, not all respirators may be adequate for all scenarios. Additionally, factors including user comfort, ease of use, and cost contribute to respirator effectiveness. Therefore, a careful consideration of these parameters is essential for ensuring respiratory protection for those working in the healthcare industry. Here respirator design and material characteristics are reviewed, as well as properties of airborne hazards and potential filtration mechanisms, regulatory standards of governmental agencies, respirator efficacy in the clinical setting, attitude of healthcare personnel toward respiratory protection, and environmental and economic considerations of respirator manufacturing and distribution.
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Affiliation(s)
- Cameron C. Young
- Division of GastroenterologyBrigham and Women's HospitalHarvard Medical School75 Francis StBostonMA02115USA
- Departments of Chemical Engineering and BiochemistryNortheastern University300 Huntington AveBostonMA02115USA
| | - James D. Byrne
- Division of GastroenterologyBrigham and Women's HospitalHarvard Medical School75 Francis StBostonMA02115USA
- Harvard Radiation Oncology Program55 Fruit StBostonMA02114USA
- David H. Koch Institute for Integrative Cancer ResearchMassachusetts Institute of Technology500 Main St. Building 76CambridgeMA02142USA
- Department of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridgeMA02139USA
- Department of Radiation OncologyDana‐Farber Cancer Institute/Brigham and Women's Hospital44 Binney StBostonMA02115USA
| | - Adam J. Wentworth
- Division of GastroenterologyBrigham and Women's HospitalHarvard Medical School75 Francis StBostonMA02115USA
- David H. Koch Institute for Integrative Cancer ResearchMassachusetts Institute of Technology500 Main St. Building 76CambridgeMA02142USA
- Department of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridgeMA02139USA
| | - Joy E. Collins
- David H. Koch Institute for Integrative Cancer ResearchMassachusetts Institute of Technology500 Main St. Building 76CambridgeMA02142USA
- Department of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridgeMA02139USA
- Division of GastroenterologyMassachusetts General Hospital55 Fruit StBostonMA02114USA
| | - Jacqueline N. Chu
- David H. Koch Institute for Integrative Cancer ResearchMassachusetts Institute of Technology500 Main St. Building 76CambridgeMA02142USA
| | - Giovanni Traverso
- Division of GastroenterologyBrigham and Women's HospitalHarvard Medical School75 Francis StBostonMA02115USA
- David H. Koch Institute for Integrative Cancer ResearchMassachusetts Institute of Technology500 Main St. Building 76CambridgeMA02142USA
- Department of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AveCambridgeMA02139USA
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Batista Napotnik T, Polajžer T, Miklavčič D. Cell death due to electroporation - A review. Bioelectrochemistry 2021; 141:107871. [PMID: 34147013 DOI: 10.1016/j.bioelechem.2021.107871] [Citation(s) in RCA: 148] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/12/2021] [Accepted: 06/03/2021] [Indexed: 12/15/2022]
Abstract
Exposure of cells to high voltage electric pulses increases transiently membrane permeability through membrane electroporation. Electroporation can be reversible and is used in gene transfer and enhanced drug delivery but can also lead to cell death. Electroporation resulting in cell death (termed as irreversible electroporation) has been successfully used as a new non-thermal ablation method of soft tissue such as tumours or arrhythmogenic heart tissue. Even though the mechanisms of cell death can influence the outcome of electroporation-based treatments due to use of different electric pulse parameters and conditions, these are not elucidated yet. We review the mechanisms of cell death after electroporation reported in literature, cell injuries that may lead to cell death after electroporation and membrane repair mechanisms involved. The knowledge of membrane repair and cell death mechanisms after cell exposure to electric pulses, targets of electric field in cells need to be identified to optimize existing and develop of new electroporation-based techniques used in medicine, biotechnology, and food technology.
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Affiliation(s)
- Tina Batista Napotnik
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Tamara Polajžer
- 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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Sengel JT, Wallace MI. Measuring the potential energy barrier to lipid bilayer electroporation. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630163 DOI: 10.1098/rstb.2016.0227] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Electroporation is a common tool for gene transfection, tumour ablation, sterilization and drug delivery. Using experimental methods, we explore the temperature dependence of electropore formation in a model membrane system (droplet-interface bilayers), using optical single-channel recording to image the real-time gating of individual electropores. We investigate the influence of the agarose substrate on electropores formed in this system. Furthermore, by examining the temperature-dependent kinetics of pore opening and closure we are able to estimate a barrier to pore opening in 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) membranes to be 25.0 ± 8.3 kBT, in agreement with previous predictions. Overall these measurements help support the toroidal model of membrane electroporation.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Jason T Sengel
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Mark I Wallace
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London, SE1 1DB, UK
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Rosazza C, Meglic SH, Zumbusch A, Rols MP, Miklavcic D. Gene Electrotransfer: A Mechanistic Perspective. Curr Gene Ther 2016; 16:98-129. [PMID: 27029943 PMCID: PMC5412002 DOI: 10.2174/1566523216666160331130040] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 11/22/2022]
Abstract
Gene electrotransfer is a powerful method of DNA delivery offering several medical applications, among the most promising of which are DNA vaccination and gene therapy for cancer treatment. Electroporation entails the application of electric fields to cells which then experience a local and transient change of membrane permeability. Although gene electrotransfer has been extensively studied in in vitro and in vivo environments, the mechanisms by which DNA enters and navigates through cells are not fully understood. Here we present a comprehensive review of the body of knowledge concerning gene electrotransfer that has been accumulated over the last three decades. For that purpose, after briefly reviewing the medical applications that gene electrotransfer can provide, we outline membrane electropermeabilization, a key process for the delivery of DNA and smaller molecules. Since gene electrotransfer is a multipart process, we proceed our review in describing step by step our current understanding, with particular emphasis on DNA internalization and intracellular trafficking. Finally, we turn our attention to in vivo testing and methodology for gene electrotransfer.
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Affiliation(s)
| | | | | | - Marie-Pierre Rols
- Institute of Pharmacology and Structural Biology (IPBS), CNRS UMR5089, 205 route de Narbonne, 31077 Toulouse, France.
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Kennedy SM, Aiken EJ, Beres KA, Hahn AR, Kamin SJ, Hagness SC, Booske JH, Murphy WL. Cationic peptide exposure enhances pulsed-electric-field-mediated membrane disruption. PLoS One 2014; 9:e92528. [PMID: 24671150 PMCID: PMC3966810 DOI: 10.1371/journal.pone.0092528] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 02/24/2014] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The use of pulsed electric fields (PEFs) to irreversibly electroporate cells is a promising approach for destroying undesirable cells. This approach may gain enhanced applicability if the intensity of the PEF required to electrically disrupt cell membranes can be reduced via exposure to a molecular deliverable. This will be particularly impactful if that reduced PEF minimally influences cells that are not exposed to the deliverable. We hypothesized that the introduction of charged molecules to the cell surfaces would create regions of enhanced transmembrane electric potential in the vicinity of each charged molecule, thereby lowering the PEF intensity required to disrupt the plasma membranes. This study will therefore examine if exposure to cationic peptides can enhance a PEF's ability to disrupt plasma membranes. METHODOLOGY/PRINCIPAL FINDINGS We exposed leukemia cells to 40 μs PEFs in media containing varying concentrations of a cationic peptide, polyarginine. We observed the internalization of a membrane integrity indicator, propidium iodide (PI), in real time. Based on an individual cell's PI fluorescence versus time signature, we were able to determine the relative degree of membrane disruption. When using 1-2 kV/cm, exposure to >50 μg/ml of polyarginine resulted in immediate and high levels of PI uptake, indicating severe membrane disruption, whereas in the absence of peptide, cells predominantly exhibited signatures indicative of no membrane disruption. Additionally, PI entered cells through the anode-facing membrane when exposed to cationic peptide, which was theoretically expected. CONCLUSIONS/SIGNIFICANCE Exposure to cationic peptides reduced the PEF intensity required to induce rapid and irreversible membrane disruption. Critically, peptide exposure reduced the PEF intensities required to elicit irreversible membrane disruption at normally sub-electroporation intensities. We believe that these cationic peptides, when coupled with current advancements in cell targeting techniques will be useful tools in applications where targeted destruction of unwanted cell populations is desired.
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Affiliation(s)
- Stephen M. Kennedy
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Erik J. Aiken
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Kaytlyn A. Beres
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Adam R. Hahn
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Samantha J. Kamin
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Susan C. Hagness
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - John H. Booske
- Department of Electrical and Computer Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
| | - William L. Murphy
- Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, United States of America
- Department of Orthopedics and Rehabilitation, University of Wisconsin, Madison, Wisconsin, United States of America
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