Objective: To investigate the effect of simulated microgravity on proliferation and adipogenic differentiation capacity of bone marrow mesenchymal stem cells (BMSCs). Methods: Part one: BMSCs were divided into two groups: normal gravity(NG) group and simulated microgravity (SMG) group (with clinostat-rotation, 30r/min). After the cells cultured for 72h, the proliferation of two groups MSCs were detected by BrdU incorporation assay. The growth curves were evaluated by cell counting. The expression of Oct4 and SSEA4 was analyzed by Western Blot. Part two: the MSCs were divided into three groups: the first group cells were induced in the NG condition with the adipogenic media after cultured in NG 72h. The second group cells were induced in the NG condition after cultured in SMG 72h and the third group were induced in the SMG condition after cultured in SMG 72 h. After 7 days, fresh oil red O solution staining was applied to examine the efficiency of adipogenic induction. Western Blotting analyzed the expression of Oct4 and PPARγ2. Results: Part one: Flow Cytometry showed the percent of BrdU+ cell was higher in SMG group than that in NG group and the attachment rate of MSCs under SMG condition was obviously higher than that under NG condition (P<0.05). Western Blotting showed cells expressed much more Oct4 and SSEA4 in SMG group than that in NG group. Red-oil O solution staining found there were more adipocyte -like cells in the second group than in the first group, but the third group nearly had no adipocyte -like cell. Western Blotting showed the higher expression of PPARγ2 in the second group was significant, compared with that in the first group, the third group only expressed little PPARγ2. In addition, Oct4 expressed more in the third group by contrasted with the little expression in the first and the second groups. Conclusion: The simulated microgravity could potentiate proliferation of BMSCs and enhance their adipogenic differentiation capacity by maintaining an undifferentiated state.%目的:探讨模拟微重力(SMG)对骨髓间充质干细胞(MSCs)的增殖及向脂肪方向分化能力的影响.方法:第一部分将第三代的MSCs分为两组,分别在正常重力下(NG组)及微重力下(SMG组,采用回转模拟装置以30r/min回转模拟微重力),培养72h后,采用BrdU标记法检测两组细胞的增殖情况,细胞计数法绘制细胞生长曲线.Western Blot检测干细胞标志物Oct4、SSEA4的表达情况,第二部分将第三代MSCs分为三组:第一组在NG条件下培养后,加入脂肪方向诱导剂在NG条件下诱导、第二组在SMG条件下培养,在NG条件下诱导,第三组在SMG条件下培养,在SMG条件下诱导.7天后,油红O染色观察脂肪方向的诱导率,Western Blot检测过氧化物酶增殖物激活受体γ2(PPARγ2)以及Oct4的表达.结果:第一部分:流式细胞仪检测SMG组BrdU标记阳性率明显高于NG组,表明细胞增殖较快,Western Blot结果显示SMG组细胞中Oct4、SSEA4的表达量明显高于NG组,有统计学意义.第二部分:脂肪方向诱导后第一组细胞油红O染色阳性,Western Blot显示PPARγ2呈阳性表达,Oct4仅有微量表达,第二组油红O染色阳性表达率明显高于第一组,且PPARγ2表达较第一组增多,几乎未见Oct4的表达,第三组细胞油红O染色阴性,且几乎不表达PPARγ2,而Oct4表达较前两组升高.结论:模拟微重力可促进骨髓间充质干细胞增殖,提高其向脂肪方向分化的能力可能与微重力保持其未分化状态相关.
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