A pilot study was conducted to examine the magnitude of cell-cycle delay and apoptosis in bone marrow (BM) cells collected at 18, 42 and 66 hr from radiosensitive CBA/CaJ mice and radioresistant C57BL/6J mice following a whole-body
in vivo exposure to 1 GeV/amu
56Fe ions or
137Cs γ rays. At each sacrifice, BM cells were collected from three mice of each strain per dose of
56Fe ions (0, 10 and 100 cGy) and two mice of each strain per dose of
137Cs γ rays (0, 100 and 300 cGy). A significant G1-arrest (ANOVA, p < 0.05) was observed at 18 hr after exposure of mice to 100 cGy of
56Fe ions or 300 cGy of
137Cs γ rays, relative to their corresponding sham-controls, resulting in a significant decrease in the percentage of cells cycling into S-phase in both strains. The percentage of S-phase cells subsequently increased and persisted up to 66 hr post-irradiation. Significant numbers of G2/M cells were found at 18 and 66 (but not at 42) hr post-irradiation, regardless of radiation-type or mouse-strain. It is likely that BM cells have undergone at least one cell cycle at 66 hr after exposure of mice to either 100 cGy
56Fe ions or 300 cGy
137Cs γ rays. Our study is the first to investigate the
in vivo effects of
56Fe ions (1 GeV/amu) on the cell cycle of mouse BM cells using flow cytometry. The cell-cycle distribution (but not the number of apoptotic cells) was dependent on radiation-dose and harvest-time.
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