Oxygen enhances lethal effect of high‐intensity, ultrashort electrical pulses

Walker, Kirk; Pakhomova, Olga N.; Kolb, Juergen F.; Schoenbach, K.H.; Stuck, Bruce E.; Murphy, Michael R.; Pakhomov, Andrei G.

doi:10.1002/bem.20200

Cited by 24 publications

(11 citation statements)

References 15 publications

(14 reference statements)

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“…The protective effect became significant for delays of over 20 min, and could be countered by mixing of the cell sample immediately prior to EP exposure. The nature of this protective effect is not completely clear; it could be caused either by gradual cell precipitation, or, more likely, by depletion of oxygen in the sample, which would inhibit the cytotoxic effect [48]. Since such protective effects could also develop during long EP exposures, we had to increase pulse repetition rate to avoid them.…”

Section: Resultsmentioning

confidence: 99%

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Selective cytotoxicity of intense nanosecond-duration electric pulses in mammalian cells

Ibey¹,

Pakhomov

Gregory

et al. 2010

Biochimica et Biophysica Acta (BBA) - General Subjects

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Background-Nanosecond electric pulses (EP) disrupt cell membrane and organelles and cause cell death in a manner different from the conventional irreversible electroporation. We explored the cytotoxic effect of 10-ns EP (quantitation, mechanisms, efficiency, and specificity) in comparison with 300-ns, 1.8-and 9-μs EP.Methods-Effects in Jurkat and U937 cells were characterized by survival assays, DNA electrophoresis and flow cytometry.Results-10-ns EP caused apoptotic or necrotic death within 2-20 hrs. Survival (S, %) followed the absorbed dose (D, J/g) as: S=αD (−K) , where coefficients K and α determined the slope and the "shoulder" of the survival curve. K was similar in all groups, whereas α was cell type-and pulse duration-dependent. Long pulses caused immediate propidium uptake and phosphatidylserine (PS) externalization, whereas 10-ns pulses caused PS externalization only.Conclusions-1.8-and 9-μs EP cause cell death efficiently and indiscriminately (LD 50 1-3 J/g in both cell lines); 10-ns EP are less efficient, but very selective (LD 50 50-80 J/g for Jurkat and 400-500 J/g for U937); 300-ns EP show intermediate effects. Shorter EP open propidium-impermeable, small membrane pores ("nanopores"), triggering different cell death mechanisms.General significance-Nanosecond EP can selectively target certain cells in medical applications like tumor ablation.

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Section: Resultsmentioning

confidence: 99%

“…The 10-ns exposure system was described previously [32, 48], and principles of its operation were outlined in [49]. In brief, to produce 10-ns EP, a Blumlein line was charged from a high-voltage DC power supply until a breakdown voltage was reached across a spark gap in a pressurized switch chamber.…”

Section: Methodsmentioning

confidence: 99%

Selective cytotoxicity of intense nanosecond-duration electric pulses in mammalian cells

Ibey¹,

Pakhomov

Gregory

et al. 2010

Biochimica et Biophysica Acta (BBA) - General Subjects

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“…Cell survival studies suggested generation of reactive oxygen species (ROS) by nsEP, and the depletion of oxygen reduced cell killing [56, 57]. Changes in the whole-cell conductance and cell morphology triggered by nsEP are similar to those of a free radical-induced necrosis [8, 17, 58].…”

Section: Discussionmentioning

confidence: 99%

Cancellation of cellular responses to nanoelectroporation by reversing the stimulus polarity

Pakhomov

Semenov

Xiao

et al. 2014

Cell. Mol. Life Sci.

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114

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Nanoelectroporation of biomembranes is an effect of high-voltage, nanosecond-duration electric pulses (nsEP). It occurs both in the plasma membrane and inside the cell, and nanoporated membranes are distinguished by ion-selective and potential-sensitive permeability. Here we report a novel phenomenon of bioeffects cancellation that puts nsEP cardinally apart from the conventional electroporation and electrostimulation by milli- and microsecond pulses. We compared the effects of 60- and 300-ns monopolar, nearly rectangular nsEP on intracellular Ca2+ mobilization and cell survival with those of bipolar 60 + 60 and 300 + 300 ns pulses. For diverse endpoints, exposure conditions, pulse numbers (1–60), and amplitudes (15–60 kV/cm), the addition of the second phase cancelled the effects of the first phase. The overall effect of bipolar pulses was profoundly reduced, despite delivering twofold more energy. Cancellation also took place when two phases were separated into two independent nsEP of opposite polarities; it gradually tapered out as the interval between two nsEP increased, but was still present even at a 10-μs interval. The phenomenon of cancellation is unique for nsEP and has not been predicted by the equivalent circuit, transport lattice, and molecular dynamics models of electroporation. The existing paradigms of membrane permeabilization by nsEP will need to be modified. Here we discuss the possible involvement of the assisted membrane discharge, two-step oxidation of membrane phospholipids, and reverse transmembrane ion transport mechanisms. Cancellation impacts nsEP applications in cancer therapy, electrostimulation, and biotechnology, and provides new insights into effects of more complex waveforms, including pulsed electromagnetic emissions.

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“…The exact mechanisms responsible for nsPEF cytotoxicity have been a subject of numerous studies [1]–[4], [11]–[17], but nonetheless remain elusive. Early studies in this area have noted fast and massive externalization of phosphatidylserine in nsPEF-treated cells, which was interpreted as a sign of apoptosis and a proof that apoptosis is the prevailing or even the sole mode of cell death after nsPEF [4], [18], [19].…”

Section: Introductionmentioning

confidence: 99%

Two Modes of Cell Death Caused by Exposure to Nanosecond Pulsed Electric Field

et al. 2013

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High-amplitude electric pulses of nanosecond duration, also known as nanosecond pulsed electric field (nsPEF), are a novel modality with promising applications for cell stimulation and tissue ablation. However, key mechanisms responsible for the cytotoxicity of nsPEF have not been established. We show that the principal cause of cell death induced by 60- or 300-ns pulses in U937 cells is the loss of the plasma membrane integrity (“nanoelectroporation”), leading to water uptake, cell swelling, and eventual membrane rupture. Most of this early necrotic death occurs within 1–2 hr after nsPEF exposure. The uptake of water is driven by the presence of pore-impermeable solutes inside the cell, and can be counterbalanced by the presence of a pore-impermeable solute such as sucrose in the medium. Sucrose blocks swelling and prevents the early necrotic death; however the long-term cell survival (24 and 48 hr) does not significantly change. Cells protected with sucrose demonstrate higher incidence of the delayed death (6–24 hr post nsPEF). These cells are more often positive for the uptake of an early apoptotic marker dye YO-PRO-1 while remaining impermeable to propidium iodide. Instead of swelling, these cells often develop apoptotic fragmentation of the cytoplasm. Caspase 3/7 activity increases already in 1 hr after nsPEF and poly-ADP ribose polymerase (PARP) cleavage is detected in 2 hr. Staurosporin-treated positive control cells develop these apoptotic signs only in 3 and 4 hr, respectively. We conclude that nsPEF exposure triggers both necrotic and apoptotic pathways. The early necrotic death prevails under standard cell culture conditions, but cells rescued from the necrosis nonetheless die later on by apoptosis. The balance between the two modes of cell death can be controlled by enabling or blocking cell swelling.

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Oxygen enhances lethal effect of high‐intensity, ultrashort electrical pulses

Cited by 24 publications

References 15 publications

Selective cytotoxicity of intense nanosecond-duration electric pulses in mammalian cells

Selective cytotoxicity of intense nanosecond-duration electric pulses in mammalian cells

Cancellation of cellular responses to nanoelectroporation by reversing the stimulus polarity

Two Modes of Cell Death Caused by Exposure to Nanosecond Pulsed Electric Field

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