An experimental study on inducing human mesenchymal stem cells into osteoblasts by different frequencies of pulsed electromagnetic fields

Objective To study the suitable frequency of pulsed electromagnetic fields (PEMF) for inducing human mesenchymal stem cells(MSCs) differentiation. Methods The third generation of human mesenchymal stem cells were irradiated by different frequencies of PEMF of 5,25,50,75,100,150Hz, 1.1mT, for 30min/d for 21 days. Morphological changes of the MSCs were observed under phase contrast microscope. The activity of Alkaline phosphatase (ALP) and the expression of osteocalcin (OC) were measured by enzymology and radioimmunity methods to evaluate MSCs differentiation. Results Different frequencies of PEMF employed in this study showed different effects in inducing MSCs into osteoblasts. The differentiation of MSCs was increasing when the frequency of PEMF was increased gradually from 5Hz to 50Hz, and then decreasing when the frequency of PEMF was increased from 50Hz to 150Hz. Conclusion Frequency of PEMF was one of the most important factors in inducing MSCs differentiation. This study indicated that 50Hz was the suitable frequency of PEMF for inducing MSCs into osteoblast in vitro.