RAT HEART-AORTA CLUSTER TRANSPLANTATION - A NOVEL MODEL TO STUDY TRANSPLANT REJECTION

The purpose of this study was to develop a microsurgical cluster model of heart plus entire thoracic aorta transplantation and to compare it to the isolated model of heart transplantation as a tool to study tra nsplant rejection. Thirty-six syngeneic (DA x DA and Lew x Lew) and al logeneic (DA x PVG and DA x Lew) cluster heart-aorta transplants were compared to 43 syngeneic and allogeneic isolated heart grafts. Graft s urvival, recipient survival and histological data on myocardial and ao rtic tissues were assessed. There was no statistically significant dif ference in graft survival between the two models studied (P > 0.05). I n the cluster transplants, the aortic component was spared the severit y of acute rejection noted for the myocardial counterpart. In conclusi on, the results demonstrated that the cluster model was technically fe asible and highly reproducible. Additionally, it was possible to apply this model to the study of experimental allograft rejection using nov el immunosuppressants. The success of the cluster model in strongly mi smatched transplant strain combinations underscores its potential for application in slower rejection combinations, making it particularly s uited for chronic rejection studies. The inherent capacity for samplin g a broader range of vessel sizes in one animal makes the cluster mode l more suitable than the isolated models of aorta or heart for applica tion to experimental protocols.