The response of mouse embryonic stem cells to low doses of γ-radiation: evidence for an adaptive response.

Low doses of ionizing radiation may induce an adaptive mechanism which protects embryonic stem cells against higher doses, a phenomenon which was reported previously for somatic cells. In this study, a possible adaptive response (AR) was evaluated by measuring cell survival (MTT assay) and chromosomal aberrations (micronucleus assay). Thymidine-synchronized mouse embryonic stem cells (mESCs) were exposed to 2.5, 3.7, or 5cGy (60)Co γ-rays and, after 5h challenged by a dose of 150cGy. mESCs pre-irradiated at 2.5cGy showed an adaptive response.