Modification of radiation injury in rats through gastrointestinal tract shielding and bone marrow therapy

The efficacy of postexposure administration of isologous bone marrow in preventing mortality was compared in whole-body x-irradiated rats and in animals exposed with three grossly different amounts of the gastrointestinal tract exteriorized and lead shielded. Survival was not enhanced by the therapy in animals which sustained severe intestinal radiation injury and died during the first postexposure week. However, significant protection was afforded by the treatment in animals in which the incidence of acute intestinal radiation deaths was reduced or virtually eliminated by intestinal shielding and deaths in the untreated controls occurred predominantly during the second postexposure week from bone marrow injury. The data demonstrate that bone marrow therapy is effective primarily in preventing deaths associated with radiation-induced damage to the hematopoietic tissue and not to the intestine, and hence its therapeutic value becomes limited as the prominence of intestinal injury increases with increasing radiation dosage in the whole-body irradiated animal.