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背景:研究证实力学刺激是影响骨改建的重要因素,可促进骨髓基质干细胞骨向分化;但不同幅度力学刺激对骨髓基质干细胞分化的影响尚不明确。目的:观察持续张应力对大鼠骨髓基质干细胞成骨分化的影响。方法:全血贴壁培养法获取大鼠骨髓基质干细胞。采用Flexercell-4000细胞体外应力加载系统对骨髓基质干细胞施加5%,10%,15%幅度的持续张应力,对照组则不加力培养,频率1Hz,持续时间48h。分别在加力后1,6,12,24,48h检测成骨标记物碱性磷酸酶、Ⅰ型胶原、骨钙素mRNA及成骨特异性转录因子Runx2的mRNA及蛋白表达。结果与结论:5%和10%持续张应力作用下,骨髓基质干细胞的成骨标记基因碱性磷酸酶、Ⅰ型胶原、骨钙素mRNA的表达较对照组升高(P<0.05),10%张力组升高的时间均较5%张力组早、幅度较高。15%持续在加力6h时可促进骨髓基质干细胞碱性磷酸酶、Ⅰ型胶原mRNA的表达(P<0.05)、随后表达下降,加力48h后上述指标均低于对照组(P<0.05),骨钙素mRNA的表达加力6h后均低于对照组(P<0.05)。5%张力组仅加力24h后骨髓基质干细胞Runx2蛋白表达高于对照组(P<0.05),10%,15%张力组加力6h后Runx2蛋白表达均高于对照组(P<0.05)。结果证实,5%,10%,15%持续张应力均可更有效地促进骨髓基质干细胞的骨向分化,10%持续张力的促进效应更显著。
BACKGROUND: It is proved that mechanical stimulation is an important factor that affects bone remodeling and promotes bone differentiation of bone marrow stromal cells. However, the effect of mechanical stimulation at different magnitudes on the differentiation of bone marrow stromal stem cells is not yet clear. Objective: To observe the effect of continuous tensile stress on osteogenic differentiation of rat bone marrow stromal stem cells. Methods: Rat bone marrow stromal stem cells were obtained by whole blood adherent culture. Continuous stress of 5%, 10%, 15% amplitude was applied to bone marrow stromal stem cells using Flexercell-4000 cells in vitro stress loading system, while the control group was not force-cultured at the frequency of 1 Hz for 48 hours. The osteogenic markers alkaline phosphatase, type I collagen, osteocalcin mRNA and osteoblast-specific transcription factor Runx2 mRNA and protein expression were detected at 1, 6, 12, 24 and 48 h after the stress. RESULTS AND CONCLUSION: Under 5% and 10% continuous stress, the mRNA expression of osteogenic markers alkaline phosphatase, type I collagen and osteocalcin in bone marrow stromal cells increased compared with the control group (P <0.05) .10 % Tension group increased time than the 5% tension group earlier, higher amplitude. 15% of rats continued to promote the expression of alkaline phosphatase and type Ⅰ collagen mRNA (P <0.05) at 6 h, and then decreased. After 48 h, the above indexes were lower than those of the control group (P <0.05) , And the expression of osteocalcin mRNA was lower than that of the control group after 6 h of loading (P <0.05). The expression of Runx2 protein in bone marrow stromal cells of 5% tension group was higher than that of control group (P <0.05) after 24 h, while Runx2 protein expression of 10% and 15% tension group was higher than that of control group (P <0.05). The results confirmed that 5%, 10%, 15% continuous tensile stress can be more effectively promote the bone marrow stromal differentiation of bone marrow stromal cells, 10% sustained tension promoting effect is more pronounced.