抄録
Pre-irradiation with 0.5Gy of X–rays to C57BL/6N mice confers resistance to the bone marrow death caused by the following 6Gy-irradiation. We previously demonstrated that hyper-proliferation of bone marrow stem cells initiated by pre-irradiation to mice was not responsible for the acquisition of radiation resistance to bone marrow death, and speculated that the pre-irradiated bone marrow stem cells might acquire radiation resistance by a new biological function rather than hematopoietic function. In the present study, we prepared radiation resistant bone marrow cells from C57BL/6N mice primed by 0.5 Gy-irradiation, irradiated the cells in vitro, and then examined the spleen colony forming ability at 12th day after grafting the irradiated bone marrow cells into the recipient mice. The result indicated that the extent of radiation resistance was different in the bone marrow stem cells prepared at 8th day and 14th day after pre-irradiation. The bone marrow stem cells derived from the mouse at 14th day after pre-irradiation showed more ability to rescue the bone marrow death even though the number of spleen colonies was similar, suggesting that radiation resistant status of bone marrow stem cells was gradually maturing in donor mice after pre-irradiation. To know a role of radiation response in this process, the kinetics of expressions of p53 and p21 genes and proteins is under investigation.
