[Effects of hypergravity on migration, proliferation and function of mouse osteoblastic cell line MC3T3-E1].

The purpose of this study was to investigate the hypergravity-induced responses and their mediators of osteoblastic cell line, MC3T3-E1. The synchronized G1 or the S Phase cells were exposed to 5 and 18 x g hypergravity at 37 degrees C. The migration velocity was measured and the morphology was observed. MC3T3-E1 cells were cultured for 1, 2 or 3 days at 37 degrees C, exposing to 5, 10, 20 and 40 x g hypergravity. The proliferation, prostaglandin E2 (PGE2) production rate and alkaline phosphatase (ALPase) activity were measured. The results were as follows: 1) In the G1 phase of the cell cycle, the migration of MC3T3-E1 cells was increased by 18 x g. In the S phase, the morphology altered depending on the g-stress. 2) The proliferation of MC3T3-E1 cells was enhanced at 20 and 40 x g but reduced at 10 x g. The proliferation of HeLa cells and JTC-12 cells was also enhanced at 40 x g. 3) Indomethacin (10(-5)M) reduced the proliferation of MC3T3-E1 cells induced by 40 x g. But indomethacin (10(-5)M) did not reduce the proliferation of HeLa cells. 4) The increase of the released PGE2 from the cells depended on the time (1-8h) and the gravity (1-40 x g). 5) The increase of the ALPase activity of MC3T3-E1 cells also depended on the gravity. These results suggest that the hypergravity enhanced the proliferation of MC3T3-E1 cells via PGE2-mediated mechanism.