Dynamics of Cell Death After Conventional IRE and H-FIRE Treatments

Borja Mercadal,Quim Castellví,Kenneth N Aycock,Rafael V Davalos,Antoni Ivorra,Natalie Beitel-White

doi:10.1007/s10439-020-02462-8

Abstract

High-frequency irreversible electroporation (H-FIRE) has emerged as an alternative to conventional irreversible electroporation (IRE) to overcome the issues associated with neuromuscular electrical stimulation that appear in IRE treatments. In H-FIRE, the monopolar pulses typically used in IRE are replaced with bursts of short bipolar pulses. Currently, very little is known regarding how the use of a different waveform affects the cell death dynamics and mechanisms. In this study, human pancreatic adenocarcinoma cells were treated with a typical IRE protocol and various H-FIRE schemes with the same energized time. Cell viability, membrane integrity and Caspase 3/7 activity were assessed at different times after the treatment. In both treatments, we identified two different death dynamics (immediate and delayed) and we quantified the electric field ranges that lead to each of them. While in the typical IRE protocol, the electric field range leading to a delayed cell death is very narrow, this range is wider in H-FIRE and can be increased by reducing the pulse length. Membrane integrity in cells suffering a delayed cell death shows a similar time evolution in all treatments, however, Caspase 3/7 expression was only observed in cells treated with H-FIRE.

Highlights

Electroporation is a biophysical phenomenon in which cells, when exposed to high electric field magnitudes, exhibit increased membrane permeability to ions and macromolecules
Our results show that conventional irreversible electroporation (IRE) and High-frequency irreversible electroporation (HFIRE) treatments can lead to either immediate or delayed cell death depending on the electric field magnitude
We showed the existence of two clearly identifiable cell death dynamics consistent with accidental cell death (ACD) and regulated cell death (RCD) in cells treated with conventional IRE and H-FIRE

Summary

Introduction

Electroporation is a biophysical phenomenon in which cells, when exposed to high electric field magnitudes, exhibit increased membrane permeability to ions and macromolecules. Irreversible electroporation (IRE) has proved to be safe and effective for the treatment of solid tumors with a non-thermal mechanism, offering a number of advantages compared to other ablation techniques.[1,10,36] IRE treatments rely on the electroporation phenomenon to kill cells by producing nano-scale defects in cellular membranes, which allow for increased transmembrane transport and eventually cause loss of homeostasis. These treatments usually consist of the insertion of metal electrodes directly into the target tissue, and delivery of multiple electric pulses with 70–100 ls pulse length. Administration of neuromuscular blocking agents and anesthesia are often necessary, increasing the complexity and cost of the entire clinical procedure

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