间歇张应力对骨质疏松大鼠骨髓基质干细胞骨向分化中细胞骨架的影响

Effect of intermittent tensile stress on cytoskeleton of bone marrow mesenchymal stem cells during osteogenic differentiation in osteoporosis rats

背景:细胞骨架在力学信号的传递中发挥着重要作用,间歇张应力可促进骨髓间充质干细胞的骨向分化,但关于骨质疏松大鼠骨髓间充质干细胞的细胞骨架在间歇张应力作用下骨向分化中的变化尚无相关报道。目的:探讨间歇性张应力在骨质疏松大鼠骨髓间充质干细胞骨向分化过程中对细胞骨架的影响。方法:建立大鼠骨质疏松模型,提取骨髓间充质干细胞进行体外培养,用FX-4000T Flexcell对细胞施加不同强度的间歇性张应力(5%,10%,15%),对照组不予施力,碱性磷酸酶染色明确骨向分化情况,激光共聚焦显微镜观察并应用Image ProPlus6.0软件进行分析,测定细胞面积、长宽比及骨架蛋白F-actin的积分荧光强度。结果与结论:力学作用下,骨质疏松大鼠骨髓间充质干细胞的排列基本垂直于加力方向,所选幅度皆可促进细胞骨向分化,以10%应变组碱性磷酸酶染色最深,15%张应力组细胞排列出现连续性中断。加力后,细胞骨架发生适应性改建,F-actin纤维束平行排列似栅栏状。图像分析显示:间歇性张应力刺激下,骨质疏松大鼠骨髓间充质干细胞面积减小(10%,15%应变组)、长宽比增加(10%,15%应变组)、F-actin表达量增加(5%,10%,15%应变组),与对照组比较差异有显著性意义(P<0.05)。由此可得,力学刺激下,在骨质疏松大鼠骨髓间充质干细胞骨向分化的过程中,细胞骨架结构发生了相应改建。

BACKGROUND：Cytoskeleton plays an important role in the transduction of mechanical signal, and intermittent tensile stress can promote osteogenic differentiation. However, there is no relevant study about the change of cytoskeleton in osteoporosis rat bone marrow mesenchymal stem cells under intermittent tensile stress. OBJECTIVE：To investigate the effects of intermittent tensile stress on the cytoskeleton of osteoporosis rat bone marrow mesenchymal stem cells during osteogenic differentiation. METHODS：Bone marrow mesenchymal stem cells were obtained from osteoporosis rats and cultured in vitro. The 5%, 10%and 15%tensile stress were strained on the bone marrow mesenchymal stem cells through FX-4000T Flexcell. No stress was in the control group. Osteogenic differentiation of bone marrow mesenchymal stem cells was observed through alkaline phosphatase staining, while the change of＆amp;nbsp;cytoskeleton was observed by confocal laser scanning microscopy with figures col ected for analysis by Image-ProPlus 6.0 software. The area of cells, ratio of length to width and integrated fluorescence intensity of cytoskeleton protein F-actin were measured. RESULTS AND CONCLUSION：Under tensile stress, bone marrow mesenchymal stem cells from osteoporosis rats arranged in the direction vertical to mechanical stimulation. cells under different tensile stress differentiated towards osteoblasts. The result of alkaline phosphatase staining showed the most significant difference in 10%group, and quite an amount of cells lining lost succession in the 15%group. Under stress, the F-actin filaments were rearranged in paral el accordingly, which showed a reconstruction of cytoskeleton. Imaging analysis indicated that the area of bone marrow mesenchymal stem cells was decreased in 10%and 15%groups （P＆lt;0.05） with the increased ratio of length to width （P＆lt;0.05）, and expression of F-actin increased in5%, 10%, 15%groups （P＆lt;0.05） after tensile stress. Under mechanical stimulation, the cytoskeleton of bone marrow mesenchymal stem cells from osteoporosis rats is shown to have corresponding alterations during osteogenic differentiation.