Electroporation is a process in which the exposure of cells or tissue to high-voltage electric pulses temporarily increases the permeability of the cell membrane, allowing the passage of various ions and molecules. The prevailing fundamental mechanism of electroporation involves the redistribution of lipid molecules in the cell membrane to form conductive pathways, known as pores. In addition to pore formation, recent research confirms that exposure to pulsating electric fields also induces chemical changes within the cell and affects the function of membrane proteins, further enhancing membrane permeability. During electroporation with electrodes made of different metals, the biological sample heats up, and electrochemical reactions occur at the interface between the electrodes and the medium. An important electrochemical process involves the oxidation of the electrode metal, leading to the release of metal ions into the biological sample. It has been shown that the release of iron ions after exposure to electric pulses, triggers processes that can lead to cytotoxicity of the medium and influence cell survival in the biological sample. Electroporation can occur reversibly, with the cell membrane gradually recovering. However, if the increase in membrane permeability is too high, it can lead to reduced ability to repair damage and cell death, a condition referred to as irreversible electroporation. The processes involved in cell membrane resealing include the release of various substances either directly through the partially permeable cell membrane or through extracellular vesicles.
The purpose of our study was to determine how electrodes made of different metals affect cellular processes after electroporation. We focused on the role of the incubation medium in the recovery of cells following electroporation with stainless steel and aluminum electrodes and its impact on the viability of cells from a fresh cell culture. We investigated how the presence of Fe2+ ions in the growth medium during electroporation with aluminum electrodes influenced the cytotoxicity of the incubation medium and observed cell membrane bleb formation after exposure to an electric field with both types of electrodes. In all experiments, Chinese hamster ovary (CHO) cells were used.
The results showed that the incubation medium after electroporation with stainless steel electrodes resulted in the death of the entire population of cells from the fresh cell culture, whereas the survival of cells from the fresh cell culture when using aluminum electrodes was comparable to the control. This suggests that the electrode material influences cellular processes post-electroporation. The added concentration of Fe2+ ions during electroporation with aluminum electrodes, which led to a statistically significant reduction in the proportion of metabolically active cells from the fresh cell culture in the incubation medium, was 5 mM. This value is slightly higher than expected and indicates that other factors, including the release of Fe3+ ions, are involved in the cellular processes that cause cytotoxicity in the incubation medium after electroporation. While observing cell membrane blebbing, it was found that electroporation with stainless steel electrodes causes more pronounced structural changes in the cell membrane. Similar effects occur with aluminum electrodes at higher electric field strengths.
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