Effects of low frequency electromagnetic field on proliferation of human epidermal stem cells: An in vitro study

To investigate the effects of low frequency electromagnetic fields (EMF) on the proliferation of epidermal stem cells, human epidermal stem cells (hESC) were isolated, expanded ex vivo, and then exposed to a low frequency EMF. The test and control cells were placed under the same environment. The test cells were exposed for 30 min/day to a 5 mT low frequency EMF at 1, 10, and 50 Hz for 3, 5, or 7 days. The effects of low frequency EMF on cell proliferation, cell cycle, and cell-surface antigen phenotype were investigated. Low frequency EMF significantly enhanced the proliferation of hESC in the culture medium in a frequency-dependent manner, with the highest cell proliferation rate at 50 Hz (P < 0.05). Exposure to a low frequency EMF significantly increased the percentage of cells at the S phase of the cell cycle, coupled with a decrease in the percentage of cells in the G1 phase (P < 0.05) but the effect was not frequency dependent. The percentage of CD29(+) /CD71(-) cells remained unchanged in the low frequency EMF-exposed hESC. The results suggested that low frequency EMF influenced hESC proliferation in vitro, and this effect was related to the increased proportion of cells at the S phase.