Electroporation (EP) is the process when cell plasma membrane gets permeabilized due to applied short, high amplitude electrical pulses. It is thought, that increased cell plasma membrane permeability is increased due to formation of electropores [1]. However, the actual mechanism of electropermeabilization remains unclear. The main electric pulse parameters that affect electroporation efficiency are pulse intensity, duration and pulse number. If any of parameter is too high, the outcome leads to a decrease in cell viability [2]. For cells to remain vital after EP, cells must restore their plasma membrane integrity. Recent studies demonstrate the importance of annexin family proteins that are fundamental proteins for injured plasma membrane repair. One of the most abundant proteins from the annexins family is the annexin A4. Through over 40 years of research on electroporation phenomenon there are barely a few investigations on protein impact on cell plasma membrane recovery. In this work we aimed to figure out how calcium affects wild type MCF7 cells, in which annexin A4 gene is fully functional compared with MCF7-ANXA4- knock out (KO) cells in which this gene expression was disturbed, after electroporation.
We used MTS method to determine cell viability. Cell plasma membrane repair and electropermeabilization dynamics were evaluated using flow cytometry measuring propidium iodide positive cells. CaCl2 concentration was 2 mM. Cells were electroporated with 1 of 100 μs duration electric pulses at varying pulse intensities.
Collected results showed that wild type MCF7 and MCF7-ANXA4- KO cells respond to electroporation at the same or very similar pattern. On the other hand, we determined that calcium did not affect propidium iodide electrotransfer but decreased cell viability and disrupted cell plasma membrane repair process leading to higher amounts of electropermeabilized cell amounts. These results suggest that annexin A4 might be not that crucial to cell plasma membrane repair after EP.