Enhancement of proliferation activity of mammalian cells by intense burst sinusoidal electric fields

This paper describes the biological response of cultured HeLa S3 cells to non-thermal, intense burst sinusoidal electric fields (IBSEF). The proliferation activity of the cells subjected to 300 kV/m, 200 μs-long IBSEF with a frequency between 0.3 MHz and 100 MHz was evaluated by using an automatic cell event monitor, xCELLigence, for 48 hours. The experiment showed that the cell proliferation depended on the pulse number and the frequency band of the IBSEF. The application of the smaller number of the pulses enhances the proliferation, whereas the large number of pulses tends to kill the cells. The dependence on the pulse number indicates the effect of the pulse is accumulated. The cells seem to be more sensitive to the pulses at the lower frequencies less than 1 MHz. The frequency of 100 MHz, which is sufficiently large for the field to penetrate into the cell, did not appear to influence the proliferation and the immediate death process. When the cells were subjected to 30 pulses of 3 MHz IBSEF, the proliferation was promoted 1.6 times as fast as that of the sham exposure. The frequency dependence of the proliferation might be associated with the electrical stress at the plasma membrane where several proteins related to the cell cycling are located.