Pulsed electromagnetic fields (PEMFs) has been clinically used for treatment of fractures. However, the mechanisms for their anabolic effects have not been yet clarified. To investigate the underlying cellular mechanisms, we measured the ALPase (alkaline phosphatase) activity, the protein content, the collagen contents, and the non-collagen contents of mouse osteoblast-Iike cells, MC3T3-E1. The cells were placed at the center of a coil and exposed to train-pulsed magnetic fields at 15 Hz with a biphasic sinusoidal wave form at 230 μsec. The intensities of the magnetic fields were 100 mT. Stimulation continued for 3 days at 20 min per day. The results were (1) the ALPase activity was not affected by pulsed electromagnetic stimulation, (2) the protein content after 7 days was significantly higher than in the control, and (3) the collagen content increased and the non-collagen decreased in comparison with the control.
These data suggest that the pulsed magnetic stimulation may activate differentiation and matrix development in osteoblasts.