Effects of the Mechanical Loading on the Proliferation and Differentiation of Osteoblast-Derived Culture Cell.

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Mechanical load play an important role on the bone growth during the formation and remodeling of the whole bone including scaletal and mandiblar bones. To clarify the effects of mechanical load on the cells growth and formation of bone, we analyzed the reactivity of osteoblast-derived cells, MC3T3-El cells, under some different kind of mechanical loads. One is gravitational vector-averaged clinorotation (GVC) which was considered to be canceled out the gravity effect on cultured cells as well as plants and animal embryos by diffusing the load. Another is centrifugation culture by which continuous high gravity was loaded on the cultured cells.We already reported that the proliferation rate of osteoblast-derived MC3T3-E1 cells was suppressed when they cultured under the GVC.The suppression rate was maximally over 65% compared to the control cells. In the present study, we performed a flow cytometric analysis using aphidicolin-treated synchronous cultured cells. As the results, it was rev … More ealed that the cell cycle was suppressed at the S phase progression and also showed a delay on the transfers from G_1 phase to S phase. On the other hand, the proliferation rate was increased when the MC3T3-E1 cells were cultured under the mechanical load produced by the centrifugation. The rate of increments of cell growth cultured under hyper gravity after 48 hr was about 13% at 30 G and about 26% at 60 G,respectively. In this case, the S phase progression was fastened about 10% compared to the control. Moreover, some of cell growth-related gene expressions were changed when they cultured under the different mechanical loads. The c-fos and c-myc expressions were transitory increased when the cell was cultured under the mechanical load. On the other hand, c-fos expression was decreased under the GVC.No difference was observed on the expression of c-jun and p53 as well as the control genes, G3PDH and beta-actin. It is important to make a series of the studies on the effect of mechanical load to the cultured osteoblasts and to be considered that it will lead us to be clarify the relationship between the mechanical load and the bone formation and remodeling. Less