ABSTRACT
When homo- or isograft was used as a right ventricle-pulmonary artery bypass in the Rastellitype procedure for congenital heart disease, reoperation was mandatory due to calcification and conduit stenosis after several years. However, the survival period of intimal cells or smooth muscle cells has not been clarified, nor has the question of whether the calcification is due to an immunoreaction or not. Thus, to observe the geometrical or pathological changes of the grafts, an experimental model of homograft transplantation was established using rats' aorta, where cyclosporine A (CsA) was given after the transplantation. The rats used were 8 or 9 weeks old. Male King rats were the donors, and female Lewis rats were the recipients. The descending thoracic aorta was transplanted to the infra-renal abdominal aorta. There were 2 experimental groups; one in which CsA was not given (<i>n</i>=35), and the other in which CsA was given (<i>n</i>=44). The animals were sacrificed at 1, 2, 4, 6, 8, and 12 weeks after the transplantation, and were examined by an optical microscope after slicing longitudinally. The area of the cross-section, intima and the media of the vessel were calculated by 2 ways; manually, and by computer. These data were used to calculate and analyze the percentage of intima-media area, the ratio of the intima/media area, and the percentage of intima area and media area. The effect of suppression of the percentage of intima-media area and the percentage of the intima area were revealed to be significant at an acute stage after brief high dose CsA administration. From this result, we suggest that there is a possibility of a rejective reaction participating in the intimal hyperplasia in the acute phase after homograft transplantation.