成骨样细胞受力后细胞骨架中微丝形态结构变化的初步研究

目的:探讨成骨样细胞株UMR-106受机械力作用后细胞骨架微丝蛋白F-actin的变化。方法:成骨样细胞株 UMR-106体外扩增,实验组以225@g相对离心力离心10 min后,分7组分别继续培养15、30 min,1、4、6、12、24 h,并设立相应对照组。所有样本经BODIPYFLPhallacidin处理后,在激光扫描共聚焦显微镜下观察、记录图片并测定单个细胞的平均荧光强度。结果:对照组F-actin较粗,呈束状,排列较整齐;实验组除24 h外,其余各组的纤维明显较对照组纤细、短,散乱分布于胞浆内、无方向性;但两组间差异随时间延长逐渐减小。除24 h外,实验组的平均荧光强度较对照组明显降低,差异有显著性;随时间延长,实验组荧光强度逐渐回升,到24 h组时较对照组增强。结论: 成骨样细胞受力后细胞骨架微丝的结构明显变化,荧光染色变弱,表明在机械力作用下微丝结构趋于解聚。去除刺激后随时间延长,实验组逐渐恢复并比对照组增高,说明细胞骨架受力后的改变是可恢复和改建的。

The Effects of the Mechanical Stress on the Cytoskeleton Filament F-actin of Osteoblast-like Cells in vitro

OBJECTIVE: Mechanical stimulation alters cell's metabolism, but little is known about the effects of mechanical strain on the cytoskeleton of osteoblasts. This study was to investigate the changes of F-actin, a cytoskeleton protein of rat-derived osteoblast-like cell line UMR-106, and to provide theoretical basis for further investigation of mechanism of bone-remodeling. METHODS: Centrifugation was used to inflict UMR-106 the top-bottom axial stress (225 x g) expected and, confocal laser scanning microscope (LSCM) was used to examine the morphological changes 15, 30 min, and 1, 4, 6, 12, and 24 hr after undergoing physical strain. Unstrained cells were used as the controls respectively. The distribution of F-actin was observed after immunofluorescent staining and electronic photo was scanned for further analysis of osteoblasts' average fluorescence by spectrofluorimetric quantification. RESULTS: Except the 24 hr group, the actin filaments of the strained osteoblasts were much shorter, more flimsy and tenuous than that of untreated osteoblasts and unlike the normal distribution of bundles or membrane-like of the control group, and they were arranged without direction. Its quantified fluorescence was significantly less than that of the controls. But the 24 hr group showed a normal distribution and a stronger fluorescence. CONCLUSION: It is concluded that the cytoskeleton of the strained osteoblasts has a reduced number of F-actin fibers and a unique abnormal morphology and could recover in 24 hr.