A potential pitfall in the use of electroporation: cellular radiosensitization by pulsed high-voltage electric fields

CHO cells have been exposed to high-voltage electric fields causing electroporation (EP) and the interaction between EP and radiation-induced cell lethality investigated. There was a voltage-dependent decrease in plating efficiency, assessed immediately following EP, and cell viability, assessed at 24 h. A linear decrease was seen for both, accompanied by a voltage-dependent increase in cell volume, assessed immediately following EP. A good correlation between increases in cell volume and decreases in plating efficiency was seen (τ = -0.91). The application of electric fields immediately prior to, or following, irradiation led to radiosensitization of the cells, which still occurred when a 6 h interval was left between radiation and EP but was lost when cells were irradiated 24 h prior to EP. When cells were irradiated following EP, radiosensitization was lost with a 1 h interval between the two treatments. (author)