In Vitro Cell Selectivity of Reversible and Irreversible

Abstract

Background - Pulmonary vein isolation (PVI) is a common catheter ablation technique used to treat atrial fibrillation originating from the pulmonary veins. However, incomplete lesion formation, pulmonary vein reconnection, and collateral damage to the phrenic nerve and esophagus can occur. Electroporation is a new modality to ablate and has the potential for permanent PVI and selective efficacy on cardiac tissue, however strong evidence of selective myocardial injury using electroporation is lacking. Methods - Monolayers of neonatal rat ventricular cardiomyocytes (NRVM), rat cortical neurons (RCN), and esophageal smooth muscle cells (SMC) were stained with propidium iodide to measure shock-induced cell death. Biphasic shocks (10 ms) were delivered from line electrodes (1 mm separation). NRVMs were optically mapped to evaluate post-electroporation electrical conduction. Results - Conduction block occurred when 50-80% of the cells near the electrode were killed, and required 400 & 50 V/cm with the electrodes in contact vs. 690 & 70 V/cm with the electrodes 1 mm above the cells (p<0.01). For 400 V/cm shocks applied in contact with cells, NRVM cultures yielded the highest degree of cell death (~60%) compared to RCN (~40%) and SMCs (~20%). When the electrode was raised 1 mm SMCs were nearly unaffected by the shock. Conclusions - Cell type alone yielded selective efficacy to electroporation without the confounding influences present in clinical studies, but electrode proximity to the target tissue remains important for efficacy. This exciting result suggests that electroporation may be a more selective modality for PVI.

Identification of electroporation sites in the complex lipid organization of the plasma membrane

“…One of the bottlenecks of electroporation is that its protocol, especially the parameters of the applied electric pulses (amplitude, duration, number, repetition rate), needs to be optimized for each specific application and also for each specific cell/tissue type ( Cemazar et al, 2009 ; Rols and Teissié, 1998 ; Hunter et al, 2021 ). When using electroporation for intracellular delivery of nucleic acids, the cells need to survive the treatment to be able to express the transgene.…”

Establishing Irreversible Electroporation Electric Field Potential Threshold in A Suspension In Vitro Model for Cardiac and Neuronal Cells

“…The data presented here showing the similar susceptibility of neurons and cardiac cells are in contrast with previous works. A recent study by Hunter et al reported that rat ventricular cardiomyocytes had more susceptibility to damage for a given field strength in contrast to cortical neurons post electroporation [14]. The difference in our study is that we used neuronal lines that are more representative of the peripheral nervous system, suggesting a possible tissue selectivity to cell injury after electroporation.…”

“…The difference in our study is that we used neuronal lines that are more representative of the peripheral nervous system, suggesting a possible tissue selectivity to cell injury after electroporation. Furthermore, in our study, HL-1 cells were extracted from adult mouse atrial cardiomyocytes in comparison to neonatal rat ventricular myocytes (NRVM) used by others [14]. In addition, immature H9C2 cardiac cells in the Kaminska et al study showed that electric field intensities of above 375 V/cm of five pulses of shorter 50 µs could cause 80% cell death [13].…”

“…IRE ablation of rat cardiomyocytes (H9C2) showed that field strengths greater than 375 V/cm significantly damaged cardiomyocytes [13]. Hunter D et al reported biphasic pulses of 500 V/cm caused 80% cell death in a monolayer of rat ventricular cardiomyocytes [14]. There is the potential for significant advances in the ability to target cells in complex tissues with IRE through optimisation of therapeutic variables such as pulse duration, frequency, amplitude, and shape.…”

Ablation Modalities for Therapeutic Intervention in Arrhythmia-Related Cardiovascular Disease: Focus on Electroporation

“…A scan of the potential range of field strengths that might induce cell death is required and would be enhanced by the addition of threshold data on neuronal, cardiomyocyte and fat tissue found in the heart. Very recently, Hunter et al showed that cardiac cells are more susceptible to electroporation damage than cortical neurons and oesophageal smooth muscle cells [ 75 ]. However, there are very few reports of this nature examining the different IRE thresholds of cardiac cells relative to other appropriate cardiac–neuronal model systems.…”