Ischemia-induced transplant arteriosclerosis in the rat.

The effect of cold graft ischemia time on the development of transplant arteriosclerosis was investigated. Aorta grafts from DA or PVG rats were stored in a cold perfusion solution for 1, 4, or 24 hours before being orthotopically transplanted to PVG recipients. After observation times ranging from 2 to 8 weeks, the grafts were examined for various cell populations. Regional changes in the intima and media layers were measured by using an image analysis system. The arteriosclerosis-like changes seen in syngeneic grafts with the longest ischemia time could be almost as prominent as those seen in the allogeneic transplants. The magnitude of the regional intima changes in the syngeneic group correlated well with the ischemia time and in the allogeneic group with the observation time. The cell composition found in the intima and media of the allogeneic vessels consisted of macrophages, T-lymphocytes, MHC class II-expressing cells, and smooth muscle cells, whereas the syngeneic grafts contained almost exclusively smooth muscle cells and macrophages. We therefore conclude that the damage due to prolonged cold ischemia time is sufficient to cause pronounced graft arteriosclerosis. The pathophysiological mechanism leading to ischemia-induced arteriosclerosis is different from the one seen in the allogeneic situation.