不同强度低频正弦交变电磁场对大鼠骨髓间充质干细胞成骨性分化的影响

Effects of low frequency sinusoidal electromagnetic fields at different intensity on osteogenic differentiation of rat bone marrow mesenchymal stem cells

目的研究不同强度低频正弦交变电磁场(Sinusoidal electromagnetic fields,SEMFs)对体外培养大鼠骨髓间充质干细胞(rat Mesenchymal stem cells,rMSCs)成骨性分化的影响,从中筛选出最佳强度参数。方法原代培养大鼠骨髓间充质干细胞,每天在频率为50 Hz,强度为0.2 mT、0.6 mT、1.0mT、1.4 mT、1.8 mT、2.2 mT、2.6 mT、3.0 mT的磁场环境中照射30 min。检测细胞碱性磷酸酶活性、骨钙素分泌量和钙化结节数;并在照射后6、9、12、24 h提取细胞总RNA,用Real-time PCR法检测成骨性分化基因Runx2/Cbfal表达情况。结果磁场干预后细胞呈漩涡状排列和生长,1.8 mT磁场强度明显促进rMSCs的成骨性分化,表现在此组的ALP活性、骨钙素分泌量、钙化结节数和Runx2/Cbfal基因的表达量均高于其他组,亦显著高于对照组(P<0.05)。结论在50 Hz、0.2～3.0 mT范围内,1.8 mT最能促进骨髓间充质干细胞的成骨性分化,是此范围内最佳的治疗用磁场参数。

Objective To investigate the effect of low frequency sinusoidal electromagnetic fields （SEMFs） at different intensities on the osteogenic differentiation of rat bone marrow mesenchymal stem ceils （rMSCs） in vitro, and to choose the best intensity parameter. Methods Primary rat bone marrow mesenchymal stem cells were obtained from Wistar rats. They were exposed to sinusoidal electromagnetic fields with 50Hz frequency and 0. 2mT, 0. 6mT, 1. 0mT, 1. 4roT, 1. 8mT, 2. 2mT, 2. 6mT and 3. 0mT intensity, respectively, 30min per day. The osteogenic differentiation was assayed by measuring alkaline phosphatase activity （ALP） , osteocalcin secretion and mineralized bone nodules. Total cellular RNA was extracted after 6, 9, 12 and 24 hours culturing and Runx2/Cbfal expression was examined using Real-time PCR. Results rMSCs were found to spread in a cireinate shape after low frequency sinusoidal electromagnetic fields treatment. 1. 8mT intensity strongly enhanced the osteogenic differentiation of rMSCs, indicated by significantly increased ALP activity, osteocalcin secretion, the number of mineralized bone nodules, and Runx2/Cbfal expression, comparing to the control and other groups. Conclusion Frequency sinusoidal electromagnetic fields at 50Hz and 0.2 - 3.0mT enhances the osteogenic differentiation of rblSCs. Among other frequencies, 1.8mT has the strongest effect on the osteogenic differentiation of rMSCs, indicating that it may be the optimal intensity for the clinical application.