title: Bipolar nanosecond electric pulses are less efficient at electropermeabilization and killing cells than monopolar pulses.
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.
authors: Radio Frequency Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA. Electronic address: bennettibey@gmail.com.
authors: Bennett L
authors: BL
authors: Ibey
authors: General Dynamics Information Systems, JBSA Fort Sam Houston, TX, USA.
authors: Jody C
authors: JC
authors: Ullery
authors: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
authors: Olga N
authors: ON
authors: Pakhomova
authors: 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.
authors: Caleb C
authors: CC
authors: Roth
authors: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
authors: Iurii
authors: I
authors: Semenov
authors: Radio Frequency Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA.
authors: Hope T
authors: HT
authors: Beier
authors: General Dynamics Information Systems, JBSA Fort Sam Houston, TX, USA.
authors: Melissa
authors: M
authors: Tarango
authors: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
authors: Shu
authors: S
authors: Xiao
authors: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
authors: Karl H
authors: KH
authors: Schoenbach
authors: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
authors: Andrei G
authors: AG
authors: Pakhomov
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D016466:CHO Cells; D002463:Cell Membrane Permeability / Q000502:physiology* / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods*; D004574:Electromagnetic Fields; D018274:Electroporation / Q000379:methods*; D006801:Humans; D019169:Jurkat Cells; D011829:Radiation Dosage
keywords: Bipolar; CHO; Calcium; FM1-43; Monopolar; Nanosecond electric pulse