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目的探讨体外间歇拉伸应变对大鼠骨髓间充质干细胞(rat bone mesenchymal stem cell,rBMSC)的增殖与成骨分化效应。方法应用Flexcell-4 000应力系统,将间歇拉伸应变(振幅10%,频率0.5 Hz,每天作用2次,4 h/次)作用于体外分离培养的正常rBMSC,加力1、3、5、7 d后检测应力对细胞形态改变、细胞增殖及骨形成核心结合因子Cbfα1、碱性磷酸酶(ALP)和I型胶原等成骨基因和Cbfα1蛋白的影响。结果 rBMSC在间歇牵拉应力作用1 d后即出现增殖速度减缓,一直延续到加力第7 d,ALP和I型胶原等成骨基因的表达自加力3 d后升高了3～6倍(P<0.05),并且Cbfα1的基因和蛋白表达在力学刺激下都出现上调。结论力学刺激在rBMSC的增殖与分化中起重要作用,适宜的间歇拉伸应变可以减缓BMSC的增殖,促进其成骨分化。
Objective To investigate the effects of intermittent tensile strain in vitro on the proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSC). Methods Flexcell-4 000 stress system was used to treat normal rBMSC cultured in vitro with intermittent tensile strain (amplitude 10%, frequency 0.5 Hz, twice daily for 4 h / time) Seven days later, the effects of stress on cell morphology, cell proliferation and bone formation such as Cbfα1, ALP and Cbfα1 were examined. Results The proliferation rate of rBMSCs was reduced after intermittent stretching stress for 1 day, and continued to increase on the 7th day. The expression of osteoblast genes such as ALP and type I collagen increased 3 ~ 6 times after 3 days (P <0.05), and the gene and protein expression of Cbfα1 were upregulated under mechanical stimulation. Conclusion Mechanical stimulation plays an important role in the proliferation and differentiation of rBMSC. Appropriate intermittent tensile strain can slow the proliferation of BMSC and promote its osteogenic differentiation.