Immunosuppressant Combinations in Primate Cardiac Xenograftsa

ABO matched cynomolgus monkey to baboon heterotopic xenografts were performed using three different immunosuppressant regimens. Group 1 (n = 4) baboons, which did not receive immunosuppression, had a mean graft survival of 9 days. Group 2 (n = 6) received cyclosporine (CsA) and methylprednisolone acetate which prolonged graft survival to an average of 78 days. Group 3 (n = 5) received CsA, Pred, and azathioprine (Aza) as well as steroid pulses and antithymocyte globulin (ATG) for rejection episodes. Survival in this group averaged 94 days. In Group 4 (n = 3), the same regimen as group 3 was used; however, Mycophenolate Mofetil was substituted for Aza. This resulted in a mean survival of 296 days. Histologic examination of the coronary vasculature in baboons treated with Mofetil showed a reduction in vascular pathologic changes when compared to those treated with Aza. Long-term cardiac xenograft survival is possible using currently available immunosuppressive agents.