Radiation Responses of Hemopoietic Colony-Forming Cells Derived from Different Sources

Originally published in Radiation Research journal vol. 24 no. 3. The Radiation Research Society holds all copyright to this article. The Society allows authors to deposit their own publications into their institutional repository.Evidence is accumulating that the regeneration of the hemopoietic system, and hence survival of the animal, after exposure to whole-body irradiation is due to the proliferation of a class of progenitor cells that possess the capacity for colony formation in the spleens of irradiated hosts. At the present time, such progenitor cells cannot be identified by histological techniques, nor have they yet been extensively purified. Thus, their only distinguishing characteristic is their ability to form spleen colonies. It is possible that this property might be shared by cells very different in other regards. Preliminary indications in favor of this view were provided by an earlier series of experiments in which it was found that colony forming cells derived from spleen colonies had a decreased capacity for self-renewal when compared with colony-forming cells derived from normal adult marrow. The fact that cells with colony-forming ability can be obtained not only from femoral marrow but also from adult spleen, peritoneal fluid and peripheral blood , fetal liver, and spleen colonies suggested another way in which the homogeneity of homopoietic colony-forming cells might be tested, since the properties of colony-forming cells from these various sources might be compared. In this paper, a comparison is made of the radiation survival curves obtained for the colony-forming ability of cells derived from femoral marrow, spleen, and fetal liver. The results indicate that the radio sensitivity of colony-forming ability can be dependent on the origin and previous history of the cells under test. This finding supports the view that hemopoietic colony-forming cells do not necessarily represent a homogeneous class of cells. On this basis, models of the effects of total body irradiation on the hemopoietic system which are based on the simplifying assumption that colony-forming cells possess a characteristic, unique radiation sensitivity may have to be modified.This research was supported by the Defence Research Board, (Grant 9350-14 G and C), by the Medical Research Council (Grant MA-1420), by the National Cancer Institute of Canada, and by the National Research Council (Grant T-1714)