Long-term effects of continuous low dose-rate gamma-ray irradiation on mouse hematopoietic cells.

This study examines the long-term effects of continuous low dose-rate (LDR) gamma-ray exposure (20 mGy/day, total doses 1–8 Gy) on hematopoietic cells in specific pathogen-free C3H/HeN mice. Results showed significant, dose-dependent decreases in colony-forming units (CFU-S and CFU-GM) in bone marrow and spleen, with reductions persisting up to 210 days postirradiation, while peripheral white blood cell counts decreased but red blood cells and platelets remained stable. Transplantation experiments using c-kit-deficient WBB6F1-W/Wv mice indicated that hematopoietic stem cells (HSCs) from irradiated mice retained their function and lifespan potential, suggesting that continuous LDR irradiation primarily affects hematopoietic stromal cells rather than HSCs themselves. These findings highlight distinct long-term impacts of continuous LDR radiation on hematopoietic tissue, with implications for understanding radiation effects on self-renewing biological systems.