Abstract:

Objective:Mechanical stimulation alters cellcs 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 basisforfurtherinvestigation ofmechanism of bone-remodeling.Methods:Cen- trifugation was used to inflict UMR-106 the top-bottom axial stress (225@g) expected and, confocal laser scanning microscope (LSCM) was used to examine the morphological changes 15, 30min, and 1, 4, 6, 12, and 24hr afterundergoing 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 osteoblastscaverage fluorescence by spectrofluorimetric quantification.Re- sults:Except the 24hr group, the actin filaments of the strained osteoblastswere 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 ar- ranged without direction. Its quantified fluorescence was significantly less than that of the controls. But the 24hr 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 24hr.

Key words: osteoblast-likecell, cellskeleton, F-actin, confocal laser scanning microscope, mechanical stress