The integrity of the cell membrane, while essential for life of any biological cell, presents a barrier that needs to be transiently disrupted in order to deliver therapeutic molecules inside the cell. High-voltage pulsed electric fields are used increasingly in medicine to achieve such a transient increase in cell membrane permeability, for example in cancer treatment for enhanced delivery of chemotherapeutic drugs and in gene therapy techniques for intracellular delivery of genetic material [Yarmush et al., Annu. Rev. Biomed. Eng. 2014, doi: DOI: 10.1146/annurev-bioeng-071813-104622].
The applied electric field induces a phenomenon called electroporation or electropermeabilization. Thanks to insights from molecular dynamics simulations we understand that one type of events that takes place in the cell membrane during electroporation is the formation of aqueous pores in the membrane lipid bilayer. However, experimental evidence suggests that membrane proteins are affected as well. Particularly voltage-gated ion channels have been identified as targets of the electric field. By using advanced patch clamp techniques, experimentalists have demonstrated that pulses with durations from nanoseconds to milliseconds can affect the conductivity of voltage-gated Na+, K+, and Ca2+ channels. Different authors have pointed to possible electroconformational damage of the channels; but without a molecular-level insight, the mechanisms by which the electric field affects these structures remain unidentified [Kotnik et al., Annu. Rev. Biophys. 2019, doi: 10.1146/annurev-biophys-052118-115451; Nesin et al., Bioelectrochemistry 2012, doi: 10.1002/bem.21696; Yang et al. PLoS ONE 2017, doi: 10.1371/journal.pone.0181002].
In this project we aim to use molecular dynamics simulations to unravel the molecular events that take place in different voltage-gated ion channels when exposing them to electric field mimicking electroporation conditions. Our results will bring much needed understanding of the effects of cell membrane electroporation on voltage-gated ion channels and the associated consequences including the post-pulse membrane depolarization observed in both non-excitable and excitable cells [Burke et al., BBA - Biomembranes 2017, doi: 10.1016/j.bbamem.2017.07.004]. We expect our results will be of especially great importance for development and optimization of electroporation-based treatments which involve excitable cells, such as irreversible electroporation of brain tumors, electroporation-mediated ablation of cardiac muscle, gene electrotransfer to skeletal muscles, and electrochemotherapy of tumors which lie in proximity of large nerves.