尾悬吊大鼠骨髓基质干细胞体外分化能力及相关因子的表达

背景：尾悬吊模拟失重可造成骨丢失，骨髓基质干细胞增殖能力与分化方向也直接影响着骨髓腔内细胞水平骨代谢的平衡并最终改变骨的质量。目的：观察尾悬吊大鼠骨髓基质干细胞体外向成骨细胞和脂肪细胞分化的能力及相关因子的表达。方法：SD大鼠随机分为正常对照组、尾悬吊组。取大鼠骨髓细胞体外培养，传1代后分别向成骨细胞和脂肪细胞两个方向诱导分化，成骨组第16天行碱性磷酸酶染色，第28天检测细胞外基质矿化能力，real-time PCR法检测第28天骨形态发生蛋白2 mRNA的表达，成脂组第21天检测脂蛋白酯酶的比活性及mRNA的表达，第30天油红O法检测脂滴形成能力。结果及结论：尾悬吊组大鼠骨髓基质干细胞成骨分化早期碱性磷酸酶阳性细胞表达率显著高于对照组，但分化晚期骨形态发生蛋白2 mRNA的表达水平及细胞外基质矿化能力较对照组显著降低；尾悬吊大鼠骨髓基质干细胞成脂分化过程中脂蛋白酯酶的表达、比活性及脂滴形成能力均显著高于对照组。说明尾悬吊可潜在刺激骨髓基质干细胞早期成骨分化能力，但显著抑制其矿化能力，从而抑制成骨，其机制可能与抑制骨形态发生蛋白2的表达有关；可显著促进骨髓基质干细胞向脂肪细胞分化。尾悬吊造成大鼠骨量的丢失可能与其对骨髓基质干细胞分化方向的影响有关。

In vitro differentiation of bone marrow stromal cells from tail-suspended rats and expression of related factors

BACKGROUND:Simulated weightlessness by tail-suspension can induce bone loss, and the proliferation and differentiation of bone marrow stromal cells directly influence the balance of bone metabolism at the cellular level in the bone marrow cavity, and finally change the bone quality.OBJECTIVE:To study the osteogenetic and adipocytic differentiation ability of bone marrow stromal cells from tail-suspended rats and the expression of related factors.METHODS:Sprague-Dawley rats were divided into two groups: control group and tail-suspended group. The bone marrow stromal cells were harvested and cultured in vitro, and induced to osteogenetic or adipocytic differentiation after the first passage. In the osteogenetic differentiation group, the alkaline phosphatase staining was performed on day 16. On day 28, the mineralization of the extracellular matrix was measured, and the mRNA expression of bone morphogenetic protein-2 was detected by real-time PCR. In the adipocytic differentiation group, the lipoprotein lipase activity and mRNA expression were detected on day 21, and on day 30, oil red O staining was performed to detect the lipid droplets.RESULTS AND CONCLUSION:In the early stage of osteogenetic differentiation of bone marrow stromal cells, the expression of alkaline phosphatase-positive cells in the tail-suspended group was significantly higher than that in the control group. But in the late stage of osteogenetic differentiation of bone marrow stromal cells, the mRNA expression of bone morphogenetic protein-2 and the extracellular matrix mineralization in the tail-suspended group was significantly lower than those in the control group. During the process of adipocytic differentiation of bone marrow stromal cells from tail-suspended rats, the mRNA expression and the activity of lipoprotein lipase as well as the ability of lipid droplets producing in tail-suspended group were significantly higher than those in the control group. Tail suspension could stimulate the osteogenetic differentiation of bone marrow stromal cells at the early stage, but it could significantly suppress other mineralizations and inhibit the osteogenetic differentiation. The mechanism might relate to the mRNA expression of bone morphogenetic protein-2. Tail suspension could promote the adipocytic differentiation of bone marrow stromal cells. The loss of the bone quality occurred in tail-suspended rat partially due to its effects on the differentiation of bone marrow stromal cells.