101
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Ibey BL, Ullery JC, Pakhomova ON, Roth CC, Semenov I, Beier HT, Tarango M, Xiao S, Schoenbach KH, Pakhomov AG. Bipolar nanosecond electric pulses are less efficient at electropermeabilization and killing cells than monopolar pulses. Biochem Biophys Res Commun 2013; 443:568-73. [PMID: 24332942 DOI: 10.1016/j.bbrc.2013.12.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 12/02/2013] [Indexed: 12/18/2022]
Abstract
Multiple studies have shown that bipolar (BP) electric pulses in the microsecond range are more effective at permeabilizing cells while maintaining similar cell survival rates as compared to monopolar (MP) pulse equivalents. In this paper, we investigated whether the same advantage existed for BP nanosecond-pulsed electric fields (nsPEF) as compared to MP nsPEF. To study permeabilization effectiveness, MP or BP pulses were delivered to single Chinese hamster ovary (CHO) cells and the response of three dyes, Calcium Green-1, propidium iodide (PI), and FM1-43, was measured by confocal microscopy. Results show that BP pulses were less effective at increasing intracellular calcium concentration or PI uptake and cause less membrane reorganization (FM1-43) than MP pulses. Twenty-four hour survival was measured in three cell lines (Jurkat, U937, CHO) and over ten times more BP pulses were required to induce death as compared to MP pulses of similar magnitude and duration. Flow cytometry analysis of CHO cells after exposure (at 15 min) revealed that to achieve positive FITC-Annexin V and PI expression, ten times more BP pulses were required than MP pulses. Overall, unlike longer pulse exposures, BP nsPEF exposures proved far less effective at both membrane permeabilization and cell killing than MP nsPEF.
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Affiliation(s)
- Bennett L Ibey
- Radio Frequency Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA.
| | - Jody C Ullery
- General Dynamics Information Systems, JBSA Fort Sam Houston, TX, USA
| | - Olga N Pakhomova
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Caleb C Roth
- General Dynamics Information Systems, JBSA Fort Sam Houston, TX, USA; Department of Radiological Sciences, University of Texas Health Science Center San Antonio, San Antonio, TX 78229 USA
| | - Iurii Semenov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Hope T Beier
- Radio Frequency Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA
| | - Melissa Tarango
- General Dynamics Information Systems, JBSA Fort Sam Houston, TX, USA
| | - Shu Xiao
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Karl H Schoenbach
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
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102
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Cell electrofusion using nanosecond electric pulses. Sci Rep 2013; 3:3382. [PMID: 24287643 PMCID: PMC3843160 DOI: 10.1038/srep03382] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 11/13/2013] [Indexed: 12/21/2022] Open
Abstract
Electrofusion is an efficient method for fusing cells using short-duration high-voltage electric pulses. However, electrofusion yields are very low when fusion partner cells differ considerably in their size, since the extent of electroporation (consequently membrane fusogenic state) with conventionally used microsecond pulses depends proportionally on the cell radius. We here propose a new and innovative approach to fuse cells with shorter, nanosecond (ns) pulses. Using numerical calculations we demonstrate that ns pulses can induce selective electroporation of the contact areas between cells (i.e. the target areas), regardless of the cell size. We then confirm experimentally on B16-F1 and CHO cell lines that electrofusion of cells with either equal or different size by using ns pulses is indeed feasible. Based on our results we expect that ns pulses can improve fusion yields in electrofusion of cells with different size, such as myeloma cells and B lymphocytes in hybridoma technology.
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103
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Sridhara V, Joshi RP. Numerical study of lipid translocation driven by nanoporation due to multiple high-intensity, ultrashort electrical pulses. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:902-9. [PMID: 24239610 DOI: 10.1016/j.bbamem.2013.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 11/01/2013] [Accepted: 11/05/2013] [Indexed: 11/16/2022]
Abstract
The dynamical translocation of lipids from one leaflet to another due to membrane permeabilization driven by nanosecond, high-intensity (>100kV/cm) electrical pulses has been probed. Our simulations show that lipid molecules can translocate by diffusion through water-filled nanopores which form following high voltage application. Our focus is on multiple pulsing, and such simulations are relevant to gauge the time duration over which nanopores might remain open, and facilitate continued lipid translocations and membrane transport. Our results are indicative of a N(½) scaling with pulse number for the pore radius. These results bode well for the use of pulse trains in biomedical applications, not only due to cumulative behaviors and in reducing electric intensities and pulsing hardware, but also due to the possibility of long-lived thermo-electric physics near the membrane, and the possibility for pore coalescence.
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Affiliation(s)
- Viswanadham Sridhara
- Center for Computational Biology and Bioinformatics, College of Natural Sciences, University of Texas, 2415 Speedway, C4500, Austin, TX 78712, USA
| | - Ravindra P Joshi
- Dept. of Electrical & Computer Engineering, Frank Reidy Center for Bio-Electrics, Old Dominion University, Norfolk, VA 23529-0246, USA.
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104
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Beebe SJ. Cell responses without receptors and ligands, using nanosecond pulsed electric fields (nsPEFs). Int J Nanomedicine 2013; 8:3401-4. [PMID: 24039422 PMCID: PMC3771745 DOI: 10.2147/ijn.s51357] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Stephen J Beebe
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
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105
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Retelj L, Pucihar G, Miklavcic D. Electroporation of intracellular liposomes using nanosecond electric pulses--a theoretical study. IEEE Trans Biomed Eng 2013; 60:2624-35. [PMID: 23674414 DOI: 10.1109/tbme.2013.2262177] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nanosecond (ns) electric pulses of sufficient amplitude can provoke electroporation of intracellular organelles. This paper investigates whether such pulses could provide a method for controlled intracellular release of a content of small internalized artificial lipid vesicles (liposomes). To estimate the pulse parameters needed to selectively electroporate liposomes while keeping the plasma and nuclear membranes intact, we constructed a numerical model of a biological cell containing a nucleus and liposomes of different sizes (with radii from 50 to 500 nm), which were placed in various sites in the cytoplasm. Our results show that under physiological conditions selective electroporation is only possible for the largest liposomes and when using very short pulses (few ns). By increasing the liposome interior conductivity and/or decreasing the cytoplasmic conductivity, selective electroporation of even smaller liposomes could be achieved. The location of the liposomes inside the cell does not play a significant role, meaning that liposomes of similar size could all be electroporated simultaneously. Our results indicate the possibility of using ns pulse treatment for liposomal drug release.
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Affiliation(s)
- Lea Retelj
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana SI-1000, Slovenia.
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