2004 年 25 巻 3 号 p. 109-117
The purpose of this study was to examine the effect of a continuous compressive force on rat bone marrow osteoblast-like cells in vitro. Approximately 5.0 × 104 cells were seeded into 35 mm dishes and cultured for 24 h. Thereafter a 2.5 × 2.5 × 0.5 cm glass (which would load the cells with approximately 0.9 g/cm2) was placed on the cell layer for 12 h, and then a glass was removed and continued culturing up to 3 days. Cells cultured without loading were used as a control. The cells were observed using both phase contrast microscopy through the transparent glass and scanning electron microscopy after fixing the cells. Quantitative RT-PCR assays for osteopontin mRNA and osteocalcin mRNA were conducted, and alkaline phosphatase activity was also evaluated. The compressed cells were oriented in mesh-like patterns, and were polygonal and flattened in shape. The compressed cells had a significant down-regulation of osteocalcin mRNA, while there were no significant differences in alkaline phosphatase activity or in osteopontin mRNA between the control and the experimental groups. These results suggest that continuous compression of the cells delays the final cell differentiation of the rat bone marrow cells to active osteoblasts.