The Influence Of Gravitational Changes On Cellular Morphology And Cell Multiplication In Human Osteosarcoma Cells And Human Umbilical Vein Endothelial Cells.

Many researches show that space flights could lead to osteopenia and cardiovascular dysfunction induced by weightlessness. The skeletal system is manifested by the loss of bone mass and bone mineral and the decline in bone mechanical function. The cardiovascular system is manifested by the decline in orthostatic tolerance and exercise tolerance, cardiac amyotrophy and arrhythmia. Bone changes are processive, which would deteriorate bone structure and function in long-term space flights. Bone mass changes are site-specific rather than even distribution and weight-bearing bones are more affected than non-weight-bearing bones. Cardiovascular system changes appear that the amount of motion and tolerance time of astronauts decrease, their indicators of HR, QO2, CO change obviously and orthostatic tolerance decline during space flights and post-space flights. During several decades of researches,the basic mechanisms of osteopenia and cardiovascular dysfunction in weightlessness have not been elucidated, and the physiological effects of counter-measures are limited. So one of the primary tasks of the space life sciences researches is to understand the basic mechanisms of the effects of weightlessness on skeleton and cardiovascular systems and develop the new effective counter-measures.One of the main reasons of osteopenia and cardiovascular dysfunction of weightlessness is the changes of cell proliferation. Cell proliferation is mainly decided by cell generation cycle. We can know the regular changes of cell generation cycle and discriminate the effects by monitoring cell generation cycle. Some researches show that cells in hypergravity or 1g condition after microgravity exposure would appear the contrary changes compared with in microgravity. We adapted intermittent hypergravity during simulated weightlessness to observe changes of cellular morphology, cell multiplication and cell cycle, the results may help us to develop more efficacious counter-measures. The main results and findings are as follows:1 The influence of gravitational changes on cellular morphology, cell multiplication and cell cycle in human osteosarcoma cells We investigated the effects of different gravitational conditions on cellular morphology, cell multiplication and cell cycle in MG-63 cells. We found:â‘ cellular morphology: compared with control group, the cell area of rotating group and intermittent hypergravity group in 24 h, 36 h and 48 h decreased significantly (P<0.05).â‘¡cell multiplication: compared with control group, cell count revealed that cell multiplications were inhibited in 12 h, 24 h, 36 h and 48 h in rotating group. Cell count increased gradually with increasing duration and intensity of hypergravity. Compared with rotating group,cell counts of Anti-1 group (6g cultured for 1 h in the centrifuge after cells cultured for 11 h in the clinostat each 12 h), Anti-2 (6g cultured for 2 h in the centrifuge after cells cultured for 12 h in the clinostat each 12 h) and Anti-4 (3g cultured for 4 h in the centrifuge after cells cultured for 8 h in the clinostat each 12 h) increased gradually, but did not reach the cell count level of control group. Compared with control group, cell count of Anti-3 group (6g cultured for 4 h in the centrifuge after cells cultured for 8 h in the clinostat each 12 h) increased significantly (P<0.05).â‘¢cell cycle: As compared with control group, the cell of rotating group and Anti-3 group in S phase of cell cycles in 24 h increased significantly, cell cycle was inhibited in S phase (P<0.05). These data indicated that microgravity can inhibit MG-63 cells multiplication and intermittent hypergravity can promote MG-63 cells multiplication.2 The influence of gravitational changes on cellular morphology, cell multiplication and cell cycle in human umbilical vein endothelial cells We investigated the effects of different gravitational conditions on cellular morphology, cell multiplication and cell cycle in ECV304 cells. We found:â‘ cellular morphology: compared with control group, the cell area of rotating group in 24 h, 36 h and 48 h decreased significantly. With increasing duration and intensity of hypergravity, the cell areas of Anti-1, Anti-2 and Anti-4 increase gradually, but did not reach the cell area level of control group. Compared with control group, cell area of Anti-3 group increased to level of control group (P<0.05);â‘¡cell multiplication: compared with control group, cell count of rotating group and Anti-3 group did not change significantly (P<0.05).â‘¢cell cycle: compared with control group, the cell of rotating group and Anti-3 group in G0+G1 phase of cell cycles in 12 h, 24 h and 36 h increased significantly, cell cycle was inhibited in G0+G1 phase (P<0.05). These data indicated that microgravity may inhibit ECV304 cells multiplication and intermittent hypergravity may promote ECV304 cells multiplication.In conclusion, we observed the influence of different gravitational environments on cellular morphology, cell multiplication and cell cycle in MG-63 and ECV304 cells. It is the main findings: simulated weightlessness can change cellular morphology of MG-63 and ECV304, inhibit cell multiplication of MG-63 and inhibit cell cycle of MG-63 and ECV304. But the influence of intermittent hypergravity increased with increasing duration and intensity of hypergravity. Our researches enrich the theories of osteopenia and cardiovascular dysfunction induced by weightlessness, offer some theoretical references for developing countermeasures.