Objective: To investigate the effect of exposure to static magnetic fields (SMFs) of 3.9 mT on proliferation and differentiation of osteoblasts in vitro. Methods: The newborn rat calvarial osteoblasts were isolated by enzyme digestion and randomly divided into 9 groups after one passage. The intensity of the SMFs was 3.9 mT. The cells were exposed in the SMFs for 0 (control group) ,0.5 ,1.0,1.5 ,2.0,2.5 ,3 ,3.5 and 4.0 h groups respectively. They were observed under the contrast phase microscope each day. After 48 h,cell proliferation was assayed by MTT method. The alkaline phosphatase (Alkaline Phos-phatase.ALP) activities and calcium content were measured after 3,6,9,and 12 days exposed with SMFs. The ALP positive colonies were histochemically stained after 8 days and the calcified nodules were stained by Alizarin Bordeaux after 10 days; BMP-2,Runx-2 and Opg mRNA expression were measured after SMFs treatment in 0,24,48 and 72 h. Results:Contrast with control group,all SMFs groups enhanced cell proliferation (P<0.01 or P<0.05),and they promoted maturation and mineralization of the osteoblasts. The results showed that SMFs improved the ALP activity, promoted calcium content, boost BMP-2,Runx -2 and Opg mRNA expression. Conclusion:The cells exposed to the SMFs of 3.9 mT at 2.5 h apparently promote proliferation and differentiation of osteoblasts in vitro.%目的:研究静磁场不同处理时间对体外培养成骨细胞增殖与分化成熟的影响.方法:原代培养大鼠颅骨成骨细胞,传代后随机分为9组,用磁场强度为3.9mT的静磁场,分别处理0(对照组)、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0h.倒置相差显微镜下观察细胞形态；48h后检测细胞增殖情况；第3、6、9、12天测定碱性磷酸酶活性和钙盐沉积量；第8天进行碱性磷酸酶染色；第10天进行茜素红钙化结节染色；在SMFs(staticmagnetic fields)处理0、24、48、72 h后,Real-time PCR检测骨形态发生蛋白(bone morphogenetic protein-2,BMP-2),Runx-2,骨保护素(osteoprotegerin,Opg)的mRNA表达水平变化.结果:与对照组相比,磁场组均促进细胞增殖(P＜0.01或P＜0.05),也能明显促进其分化成熟,表现为提高细胞的ALP活性,促进钙盐沉积量,提高BMP-2、Runx-2和Opg的mRNA表达.结论:磁感应强度为3.9 mT的静磁场处理体外培养成骨细胞2.5 h时,其对成骨细胞的增值与分化效果最为明显.
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