Diverse effects of nanosecond pulsed electric fields on cells and tissues.
The application of pulsed electric fields to cells is extended to include nonthermal pulses with shorter durations (10-300 ns), higher electric fields (< or =350 kV/cm), higher power (gigawatts), and distinct effects (nsPEF) compared to classical electroporation. Here we define effects and explore potential application for nsPEF in biology and medicine. As the pulse duration is decreased below the plasma membrane charging time constant, plasma membrane effects decrease and intracellular effects predominate. NsPEFs induced apoptosis and caspase activation that was calcium-dependent (Jurkat cells) and calcium-independent (HL-60 and Jurkat cells). In mouse B10-2 fibrosarcoma tumors, nsPEFs induced caspase activation and DNA fragmentation ex vivo, and reduced tumor size in vivo. With conditions below thresholds for classical electroporation and apoptosis, nsPEF induced calcium release from intracellular stores and subsequent calcium influx through store-operated channels in the plasma membrane that mimicked purinergic receptor-mediated calcium mobilization. When nsPEF were applied after classical electroporation pulses, GFP reporter gene expression was enhanced above that observed for classical electroporation. These findings indicate that nsPEF extend classical electroporation to include events that primarily affect intracellular structures and functions. Potential applications for nsPEF include inducing apoptosis in cells and tumors, probing signal transduction mechanisms that determine cell fate, and enhancing gene expression.
Beebe
Stephen J
SJ
Eastern Virginia Medical School, Norfolk, Virginia 23510, USA. sbeebe@chkd.com
White
Jody
J
Blackmore
Peter F
PF
Deng
Yuping
Y
Somers
Kenneth
K
Schoenbach
Karl H
KH
D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D018274:Electroporation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D018922:HL-60 Cells / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D012513:Sarcoma, Experimental / Q000378:metabolism* / Q000517:prevention & control; D015398:Signal Transduction
D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D020169:Caspases; D002118:Calcium