2011 年 28 巻 2 号 p. 41-
Weightlessness conditions result in bone loss, which may be partly attributed to the dysfunction of osteoblast. Random positioning machine (RPM) was often used to simulate the weightlessness effects on animal cells. The aim of this study was to explore the response of MC3T3-E1 osteoblast-like cells to the specific mechanical environment in RPM. The results showed that RPM exposure for 12 and 24 h inhibited the cell proliferation, and changed the cell shape for 12h, but had no effect for 48 h. The stress fibers of MC3T3-E1 cells cultured in RPM for 12 and 24 h disrupted detected by rhodamine-labeled phalloidin, but partially recovered for 36 and 48h. The cytosolic free calcium concentration ([Ca2+]i) of MC3T3-E1 cells cultured in RPM for 12 and 24h increased. The cell migration of MC3T3-E1 cells cultured in RPM inhibited for 12, 24, 36 and 48 h. Based on these findings, it appears reasonable to suggest that RPM affects the osteoblastlike cell shape, F-actin distribution, proliferation for 12 and 24 h, but the cells recovered for 36 and 48 h except cell migration. From these results, we conclude that MC3T3-E1 cells cultured in RPM at early stage could response to the new mechanical stress and display the weightlessness effects.