The role of cyclosporin in prolonging survival in vascularized bone allografts

It is known that experimental vascularized bone allo-grafts are subject to host rejection. To be useful clinically, this rejection response would need to be controlled. Cyclosporin is a potent immunosuppressant whose precise role in vascularized bone allograft transplantation has not been established. Using a proven reliable vascularized knee allograft model in inbred rats, cyclosporin was used postoperatively both continuously and short term (14 days after transplant) at 10 mg/kg per day as recipient treatment. Across a strong histocompatibility barrier, continuous cyclosporin was required for long-term graft survival. Short-term therapy delayed rejection for 4 to 6 weeks. However, across a weak histocompatibility barrier, short-term therapy was as effective as continuous therapy in achieving long-term graft survival. The implication is that a limited course of cyclosporin may be clinically successful in sustaining vascularized bone allograft survival, provided the genetic disparity between graft and host has been minimized by genetic matching techniques.