Mechanism Study On The Damage Of Vascular Endothelial Cells Induced By Carbon Ion Radiation And Simulated Microgravity

Purpose: With the rapid development of manned spaceflight and the completion of the space station,human exploration of the universe is also deepening,astronauts will stay longer and longer in space,the most important factor that affects human long-term stay in space is the special space environments.Among many environmental factors,space radiation and microgravity are considered to be two major and inevitable risk factors affecting the health safety of astronauts,especially space high-energy heavy ion radiation.The study of the effects of heavy ion radiation and microgravity on the cardiovascular system and related molecular mechanisms can help us understand the cardiovascular health risks of space flight,it is also of great significance for the development of strategies for cardiovascular risk.In this study,vascular endothelial cell(EC)was used to study the damage effects of high-energy and low-dose carbon ion radiation on EC,to investigate the effects of simulated microgravity on EC,and the influence of simulated microgravity on the damage effect of carbon ion radiation.The mechanism underlying the effects of carbon ion radiation and simulated microgravity alone or in combination on the injury and dysfunction of EC were elucidate based on the transcriptomics.The results will provide new insights into the molecular basis of EC damage caused by heavy ion radiation,and are of great significance for the cardiovascular system risk assessment of space flight personnel.Materials and Methods: Human umbilical vein endothelial cells(Ea.hy926)were used for the studies.The clinostat model system was used to simulate the effect of space microgravity.Ea.hy926 cells were exposed to carbon ion radiation,to simulated microgravity,or to the combination of carbon ion radiation and simulated microgravity,then cell survival was detected by CCK-8 method,cell cycle distribution and DNA damage were detected by flow cytometry,cell adhesion ability was detected by Matrigel matrix method,cell migration was detected by cell scratch test,the formation of tube-like structures on Matrigel was assessed,then we did transcriptomic sequencing to find differential genes in cells with different treatment and analyzed the functions of these differential genes.Results: Carbon ion radiation dose-dependently reduced the survival of Ea.hy926 cells,induced S phase arrest and DNA damage,decreased the cell adhesion and migration ability,but the ability of tube formation was increased.The effect of simulated microgravity on cell viability was related to the rotation culture time,in the range of 0.5 h-24 h,the cell viability increased with time,but was lower than that of the control group.Rotating culture for 0.5 h resulted in a decrease in cell adhesion ability,significantly increased the cell migration ability,the tubular structure formation ability was also increased.Compared with the untreated group,the combined of carbon ion irradiation and simulated microgravity could reduce the survival rate of cells,caused serious S-phase arrest and DNA damage,cell adhesion ability was decreased,while the ability of cell migration and tubular formation were increased.when compared with the irradiation group,the survival of Ea.hy926 cells was slightly decreased,adhesion ability,migration ability and tube forming ability were slightly lower,the change of distribution of cell cycle not obvious.Transcriptomic sequencing showed that carbon ion radiation or simulated microgravity treatment could significantly change many genes expression levels,the combined treatment of carbon ion radiation and simulated microgravity also changed many genes expression levels,but these genes were significantly different under the three treatments.Conclusion: Both carbon ion radiation and simulated microgravity could cause the Ea.hy926 cell function disorder,simulated microgravity affects Ea.hy926 cell dysfunction induced by carbon ion radiation.Carbon ion radiation and simulated microgravity alone or combination treatment induce Ea.hy926 cell different molecular response,and there is an interaction between carbon ion radiation and microgravity.