In vivo radiosensitivity and recovery pattern of the hematopoietic precursor cells and stem cells in mouse bone marrow.

Survival curves were determined for colony-forming hematopoietic stem cells (CFU-Mix and CFU-S10) as well as precursor cells (CFU-E, CFU-C, CFU-F, and BFU-E) in bone marrow of the mouse at various times up to 4 weeks after whole-body irradiation (1.5 or 3.0 Gy) in order to elucidate in vivo radiosensitivity and recovery patterns. These measurements represented the first attempts to examine CFU-Mix simultaneously with the other cell populations. CFU-E (D0 = 53 rad) and BFU-E (D0 = 68 rad) were the most radiosensitive. CFU-S10 (D0 = 81 rad) had intermediate radiosensitivity. CFU-Mix (D0 = 144 rad) and CFU-C (D0 = 157 rad) were relatively radioresistant. CFU-F (D0 = 257 rad) was the most radioresistant. The precursor and stem cells could be classified into three groups based on the recovery pattern. The first group, consisting of CFU-Mix, BFU-E, and CFU-S10, showed very slow recovery and did not reach normal levels even after day 28. CFU-E, the second group, showed the most severe depletion immediately after irradiation, and recovered most quickly with an overshoot at day 5. CFU-C and CFU-F cells, forming the third group, decreased more gradually and slightly, and recovered to the normal level after a transient rise by day 10-14.