The Effect of Low Voltage High Frequency Electric Pulses on The Extracellular Conductivity, Cell Permeability and Time-Depended Manner of MCF7 Cell Line

Background: Low voltage, high frequency electrochemotherapy (LVHF ECT) has recently been explored as a method to enhance the permeability of cell membranes to non-permanent chemotherapeutic agents. Objective: Despite recent advances, it remains unclear whether classical ECT and LVHF ECT (using 50–150 V/cm at pulse frequencies of 4–6 kHz) affect the cell membrane through similar mechanisms. Materials and methods: We investigated the efficiency of reversible membrane permeabilization in the MCF7 cell line induced by LVHF electric pulses. Specifically, we examined changes in extracellular conductivity, the time-dependent nature of permeabilization, and the effects of this protocol on commonly used permeabilization markers Results: LVHF ECT protocols significantly increased the conductivity of the extra-cellular medium, indicating enhanced membrane permeability in MCF7 cells. This increased permeability was closely associated with elevated membrane conductivity. Notably, most of the membrane permeabilization occurred during pulse application and subsided within one minute after the delivery of LVHF pulses. Experimental data indicate that these electric pulses induce the formation of short-lived pores in the membrane. Furthermore, LVHF pulses did not alter the cytotoxicity of bleomycin; however, this protocol resulted in the quenching of Lucifer yellow fluorescence, a classical marker for membrane permeabilization. These findings suggest that bleomycin is a reliable marker for cell electro permeabilization under LVHF ECT conditions. Conclusion: Our results demonstrate that LVHF ECT induces transient, short-lived pores in the cell membrane and increases membrane permeability without affecting bleomycin cytotoxicity. Bleomycin appears to be a suitable marker for assessing electro-permeabilization in this context.