[Enhancement of osteoblastic differentiation of bone marrow mesenchymal stem cells in rats by sinusoidal...

The present research was aimed to investigate the effects of sinusoidal electromagnetic fields (SEMFs) on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells in rats (rBMSCs) and to find out the intensity with the best therapeutic efficacy. Primary rat bone marrow mesenchymal stem cells were obtained from Wistar rats and screened by the adhesive method. The rBMSCs were exposed to sinusoidal electromagnetic fields with 50Hz frequency and intensities of 0 mT, 1.4 mT, 1.6 mT, 1.8 mT, 2.0 mT, and 2.2 mT respectively, 30 min per day. The proliferation of the rBMSCs was analyzed by MTT reduction assay. The osteogenic differentiation markers including ALP activity, calcium deposition, mineralized bone modulus and collagen I expression were compared between the rats in the exposed groups and those in the control group. The total cellular RNA was extracted after 6, 12, 24 and 48 hours, respectively. The gene expression of Osterix and IGF-1 was examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The absorbance of exposed groups was suppressed significantly in comparison with that in the control group. The exposure to the rBMSCs with intensity of 1.8 mT strongly enhances the osteogenic differentiation of rBMSCs, indicated by remarkably improved ALP activity, calcium deposition, collagen I expression and the number of mineralized bone nodules compared to that in the control group and other groups. Osterix and IGF-1 were also significantly improved (P < 0.05). The SEMFs with frequency and 50Hz and 1.4-2.2 mT intensities enhanced the osteogenic differentiation of rBMSCs, but inhibited their proliferation in the presence of 0.1% serum culture. Among the rBMSCs used in the tests, the one with 1.8 mT had the strongest activity, indicating that it could be the optimal intensity for the clinical application.