Radioprotective potential of primitive hematopoietic precursors forming colonies in diffusion chambers in mice

The purpose of this study was to determine the radioprotective ability of primitive hematopoietic precursors which form colonies in diffusion chambers in mice (CFU-D). Thirty-two lethally irradiated female ICR mice were injected with 5 to 7 male ICR mouse bone marrow-derived CFU-D colonies each. Fourteen of these mice survived over 30 days and were sacrificed at intervals up to a year. As a control, 20 lethally irradiated female ICR mice received cells from intercolony areas. All of these mice died before day 20. DNA samples obtained from hematopoietic organs and liver from 8 sacrificed mice were analyzed for the presence of CFU-D colony-derived cells. Only in 1 ICR mouse was CFU-D colony origin DNA detected by Southern analysis in all hematopoietic organs: bone marrow, spleen, thymus and lymph nodes. In 6 mice, only selected hematopoietic organs were repopulated by CFU-D colony-derived cells as judged by Southern analysis. In some of these mice, the remaining hematopoietic organs contained small CDU-D-derived cell populations which could be detected by more sensitive polymerase chain reaction (PCR). In 1 mouse, the presence of CFU-D-derived cells in all hematopoietic organs was only demonstrated by PCR. These findings suggest that lethally irradiated mice can be rescued by CFU-D-derived daughter cells. They appear to have the potential to give rise to clones containing lymphoid and myeloid cells in all hematopoietic organs, at least temporarily. Thus, it can be concluded that CFU-D represents a very primitive hematopoietic precursor cell with radioprotective capability.