Osteoblast-like Cell Behavior under Mechanical Loading in vitro

Objective: The purpose of this study was to examine the effect of mechanical loading on the behavior of osteoblast-like cells in vitro. Methods: Bone marrow osteoblast-like cells were obtained from male Wistar/ST rats (100-110g) according to the methods of Maniatopoulous (Cell Tissue Res. 1988). Five days after the primary culture, cells were detached using 0.1% trypsin with 0.02% EDTA Approximately 5.0x104 cells were seeded in the 35mm dishes and cultured for 24 hours, and then 2.5x2.5x0.5mm cubic shape glass (0.9g/cm2 load) was placed on the cell layer for 12 hours. Cultured cells without loading were used as a control. The cells were observed using either the phase contrast microscopes or scanning electron microscopes. An alkaline phosphatase activity and a quantitative PCR assay of OCNmRNA with a Light-CyclerTM using the double stained DNA dye SYBR Green‡T were conducted. The data were analyzed by two sample t-test. Results: The cells of control group were spindle morphologically. While the cells of loading transformed irregular shape. Alkaline phosphatase activities of control groups (0.075±0.015[uMol/ug/sec]) were significantly higher than those of experimental groups ( 0.049±0.012[uMol /ug/sec]). OCNmRNA expression of control groups were upregulated than that of loading groups. Conclusion: These results suggested that loading mechanism might inhibit osteogenic activity of the rat bone marrow cells. This study was partly surported by Tokyo Dental College Grant (HRC5A08).