Pulmonary injury and repair. Organ culture studies of murine lung after oxygen.

Samples of mouse lung were cultured at various stages of the injury-repair cycle induced by oxygen. At intervals during and after a six-day exposure, pulmonary explants were prepared and cultured in media labeled with tritiated thymidine. Lungs cultured during the first three days in oxygen, when only interstitial edema was observed, resembled control explants in morphologic features and labeling. Cultures prepared from animals after four to six days of exposure, when necrosis of type 1 epithelial cells and hyaline membranes were observed, showed reduced thymidine uptake and reduced epithelial regeneration. Fibroblastic proliferation and collagen deposition occurred directly beneath areas with hyaline membranes, indicating that, in severely damaged lungs, cellular proliferation is predominantly fibroblastic rather than epithelial. The results suggest that the organ culture system is suitable for studying the reparative capacity of injured tissue.