A 2-D Cell Layer Study on Synergistic Combinations of High-Voltage and Low-Voltage Irreversible Electroporation Pulses

Irreversible electroporation (IRE) employs brief, high-electric field pulses to ablate tumors while preserving the extracellular matrix. Recently, we showed that combining short high-voltage (SHV) IRE pulses and long low-voltage (LLV) IRE pulses can enlarge the tissue ablation region, presumably through a synergistic effect. OBJECTIVE: The goal of this study is to further investigate the effect of this combination on a 2-D cell layer tumor model. METHODS: 2-D layers of tumor cells are exposed to various SHV and LLV combinations, and the results of propidium iodide (PI) and fluorescein diacetate staining are examined to correlate treatment protocols with the ensuing irreversible and reversible electroporation areas. RESULTS: The combination of SHV+LLV pulses produces a larger area of electroporation and ablation than LLV+SHV pulses, LLV pulses alone, and SHV pulses alone. CONCLUSION: Judiciously combining SHV and LLV pulses can produce a synergistic effect that enlarges the electroporation-induced ablation area. A hypothetical explanation for this effect is that it involves a combination of pore expansion and electrolysis induced by LLV pulses in the area that had been reversibly permeabilized by the SHV pulses. SIGNIFICANCE: This paper is valuable for the design of improved IRE protocols and provides a hypothesis for the mechanisms involved.