2021 年 35 巻 p. 15-23
To understand the combined effect of microgravity (μG) and space radiation on cells is an important requirement for the anticipated space travel by humans. Cultured cells, such as human fibroblasts and lymphoblasts, were used in previous studies, and we observed changes in the expression of some cell-cycle-related genes and increased chromosome aberrations (CAs) in these cells under simulated μG. In this study, we investigated the combined effect of μG and space radiation on human peripheral blood lymphocytes. Whole blood was irradiated with X-ray or carbon-ion (C-ion) beam while being exposed to simulated μG using a three- dimensional clinostat. The frequency of CA was assessed using the three-color fluorescence in situ hybridization on chromosome spreads of colcemid-induced prematurely condensed chromosomes in lymphocytes during the first cell division post irradiation. Compared with the cells irradiated at 1G, the frequency of CA was increased in cells simultaneously exposed to simulated μG and radiation even though cells were irradiated by the same doses (0.5–1.0 Gy). This result is similar to those of our previous studies in which we used human lymphoblast TK6 cells and human fibroblast 1BR-hTERT cells. These ground-based experiments give insights into the biological effects of the space environment where radiation and μG coexist.
