Experimental treatment of total-body irradiation injury: a brief review.

By C. C. CONGDON W IDE INTEREST in the experimental treat-meat of tot-al-body irradiation injury by post-irradiation injectioii of living blood-forming cells is evident from the many reports in this field. Discussions among biologists amid medical workers indicate an active interest in the potential applications of this particular radiobiologic research to human disease. The results of an animal experiment in this laboratory illustrate how’ dramatic the experimental treatment can be in preventing death from the acute radiation syndrome (table 1). Treatmentof total-body injury from x-rays has been mostextensively studied. IIow’ever, iiiject-ion of bone marrow cells was also effective in lethal external gamma and fast neutron exposures.1 . 2 Acute mortality from the mixed radiations given off by intravenous radon in equilibrium w’ith its decay product-s was reduced by administration of bone marrow atthe proper interval after the radon iilj ectioii 1 The amountof hone marrow or other blood-forming tissue injected after a lethal exposure determines the percent-age survival at 30 days. The data in mice vary somewhat from one st-rain to another or from one F1 hybrid to another, probably depending on variation in individual resistance to irradiation. In general, 1 to 10 X 106 nucleated bone marrow’ cells gives optimum 30-day survival in mice aft-er exposure to 900 r of x-rays. However, as few as 50,000 nucleated i)lood-formiimg cells will allow a low percentage of mice to survive 30 days in some experiments.3 . If, instead of 30-day survival, the bone marrow of the irradiated hostis quamit-it-atively studied to determine the effect of different doses of bone marrow administered, response is proportional to dose over a much greater range than w’hen survival is used as the endpoint.3 The effective cell type, or types, in the administered blood-forming tissue has niotbeen clearly determined. Since dividing cells are necessary, the stem cells and reticulum cells of the hemat-opoictic tissues are implicated.5 The intravenous route of injection gives the best30-day survival in mice and guinea pigs. Imitraperitoneal inject-ion is effective but not so effective as intravenous. Intrapleural and intrasplenic injections were also effective, but intramuscular and subcutaneous injections did not. cause survival of lethally irradiated