Effects of direct current electric field on proliferation and biological characteristics of human adipose derived mesenchymal stem cells

Objective To investigate the effect of direct current (DC) electric field on the proliferation of human adipose-derived stem cells (hASCs) in vitro. Methods The fat tissue obtained in operation was digested with zymogen to prepare hASCs. After the cell culture was passaged to the third generation, the hASCs were inoculated in a 6-well plate. After 24 h, the cells were cultured under a stimulation of 0, 50, 100, 150 and 200 mV/mm DC electric field, at a frequency of 1 h/d for 3 continuous days. Cell morphology and growth were observed under an inverted microscope. Cell counting and CCK8 assay were carried out to measure cell proliferation. Flow cytometry was performed to detect the expression of stem cell phenotype markers, CD105, CD73, CD90, CD14, CD34, CD31 and CD45. The effect of DC electric field stimulation was observed after differentiation induction. Western blotting was used to detect the expression of proteins related to cell proliferation in stimulated and unstimulated cells. Results The proliferation rate and absorbance value were significantly higher in the cells after 50, 100 and 150 mV/mm stimulation than those without (all P < 0.01). When the stimulation intensity of the DC electric field was increased to 200 mV/mm, the proliferation rate was significantly lower (P < 0.001), but the absorbance value was statistically higher than those of the 0 mV/mm stimulation (P < 0.05). The stimulation also resulted in remarkably higher expression of CD105, CD73 and CD90, and lower expression of CD14, CD31, CD34 and CD45. Moreover, the hASCs could differentiate into bone cells and adipocytes with and without DC electric field stimulation, but the stimulated cells had faster differentiation than those without. Compared with the unstimulated cells, the expression of cell proliferation related protein p-ERK1/2 was significantly increased in the stimulated cells (P < 0.01). Conclusion The DC electric field promotes the proliferation of hASCs probably by regulating the phosphorylation of ERK, but has no effect on the biological characteristics of the stem cells