Cell size change after electroporation and its influence to triggered electrotransfer

Abstract

When cells are exposed to a pulsed electric field with a sufficient amplitude, their transmembrane potential (TP) increases. If the TP increase surpasses the threshold, then pores start to form in an affected membrane. This phenomenon is termed as electroporation (EP). The pores that are induced by EP are hydrophilic and act as a bridge for exogenous molecules. This way, the intracellular electrotransfer (ET) of such molecules is initiated [1]. This technique can be applied as a local cancer treatment (electrochemotherapy, calcium electroporation) as well as for gene transfer to cells and tissues.The electric field triggered TP (Utp) can be counted by simplified Schwan equation shown in Eq. 1 [2].𝑈𝑡𝑝 = 1.5𝐸𝑟𝐶𝑜𝑠Θ (1)Were, E is external electric field strength, r is the radius of the cell and Cos is the angle between electric field line in between the electrodes that passes through the centre of the cell and the area on the cell membrane were the TP will be counted. From the Eq. 1 one can already observe that the radius of the cell is directly proportional to the induced TP values. However, due to the processes of molecule ET, diffusion and then induced osmose the size of the cell can change, hence changing the sensitivity to future induction of EP and ET [3]. Here we tested the hypothesis of cell size change after EP and its influence on efficiency of molecule ET. CHO cell line was used for experiments. Cells were electroporated in these different mediums using 1, 2, 4, 8 impulse sequences of 100μs duration (1Hz frequency), and amplitude of 1400V/cm. 10 minutes after electroporation cells were transferred to a hemocytometer and imaged using light microscope. The sizes of the cells were measured by using open-source ImageJ software. The experiment was conducted in triplets, each time 300 cells were measured, and the average is derived [...]