背景：在体外和体内关于细胞对于不同的机械牵张反应的大量研究表明，牵张能够刺激成骨。然而鲜有文献报道不同的牵张方式对于同种细胞的影响有何不同。 目的：比较不同机械牵张方式对大鼠骨髓间充质干细胞的影响。 方法：分离培养大鼠骨髓间充质干细胞，应用自行研制的牵张装置对骨髓间充质干细胞分别施加动态、静态和模拟临床的混合牵张牵张刺激，分别检测3种刺激方式下骨髓间充质干细胞的增殖能力、碱性磷酸酶活性及Runx2基因的mRNA表达，并测量细胞骨钙素的分泌情况。 结果与结论：静态牵张组与对照组相比，细胞增殖能力提高18.67%，碱性磷酸酶活性、Runx2表达及骨钙素分泌无明显差异；动态牵张组相对于对照组，细胞碱性磷酸酶活性提高60.33%， Runx2表达上升49.67%，细胞外骨钙素的分泌提高了48%，然而细胞增殖则受到了抑制；混合牵张组相对于对照组，细胞增殖能力稍有上升但无统计学差异，其对碱性磷酸酶活性、Runx2表达以及骨钙素的分泌有一定的促进作用，但没有动态牵张组明显。结果提示，静态牵张能够显著刺激骨髓间充质干细胞的增殖，而动态牵张对于刺激骨髓间充质干细胞成骨向分化作用更为明显，混合牵张方式对于细胞增殖及成骨分化均有一定的促进作用。%BACKGROUND:In vitro and in vivo studies of cel response to a variety of mechanical loadings have demonstrated the stimulation of bone formation by loads. However, the effects of different mechanical strains on the same cel s have never been adequately studied by far. OBJECTIVE:To investigate the effects of different mechanical strains on rat bone marrow mesenchymal stem cel s. METHODS:Rat bone marrow mesenchymal stem cel s were isolated and cultured in vitro. Bone marrow mesenchymal stem cel s were subjected to different stimulations including dynamic stretch, static stretch and hybrid stretch through the use of custom-made mechanical stretch device. Cel ular proliferation, alkaline phosphatase activity and mRNA expression of Runx2 of bone marrow mesenchymal stem cel s were detected and the secretion of osteocalcin was evaluated under three different stretch modes respectively. RESULTS AND CONCLUSION:Compared to the control group, cel proliferation increased by 18.67%, however, alkaline phosphatase activity, Runx2 expression and osteocalcin secretion were not changed obviously in the static stretchgroup. Compared to the control group, alkaline phosphatase activity, Runx2 expression and osteocalcin secretion increased by 60.33%, 49.67%and 48%respectively;however, cel proliferation was inhibited, in the dynamic stretch group. Compared to the control group, cel proliferation was slightly, but not significantly, increased in the hybrid stretch group, and the alkaline phosphatase activity, Runx2 expression and osteocalcin secretion increased although the increases were not as apparent as those in the dynamic stretch group. These findings suggest that static mechanical strain can significantly promote cel proliferation, the dynamic mechanical strain more greatly promotes osteogenic differentiation of bone marrow mesenchymal stem cel s, and the hybrid mechanical strain promotes the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cel s.
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