Abstract: Objective To investigate the effect of exposure to 0.25 T, 0.35 T, 0.42 T static magnetic fields (SMF) on the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs). Methods Primary bone marrow MSCs were obtained from Sprague-Dawley rats and screened by adhesive method. MSCs were exposed to 0.25 T, 0.35 T, 0.42 T SMF continuously and 24 h intermittently respectively.The cell proliferation activity was detected by Cell Counting Kit (CCK-8) assay. The osteogenic differentiation markers including alkaline phosphatase (ALP) activity and osteocalcin were analyzed after continuously exposure to 0.35 T SMF. Results Compared with the control group, the proliferation activity of SMF-treated cells significantly decreased, especially on the 7th day (P<0.001) after continuous exposure,and on the 2nd to 8th day in 0.25 T, 0.35 T SMF intermittent exposure groups (P<0.001). Both the alkaline phosphatase activity and the level of osteocalcin significantly increased in MSCs after continuous exposure to 0.35 T SMF (P<0.05). Conclusion Continuous or intermittent exposure to 0.25 T, 0.35 T and 0.42 T SMF could effectively inhibit the proliferation of MSCs. Continuous exposure to 0.35 T SMF could enhance the osteogenic differentiation of MSCs.

Key words: static magnetic field, mesenchymal stem cells, proliferation, osteogenic differentiation, rats