Vascularized bone marrow allotransplantation and low-dose cyclosporine prolong the survival of adipose tissue allografts

BACKGROUND: Composite tissue allotransplantation holds promise in reconstructive surgery, but its application is limited by the need for long-term immunosuppression. The objective of this study was to investigate the feasibility of low-dose cyclosporine and vascularized bone allotransplantation in prolonging the survival of vascularized adipose tissue allograft. METHODS: In the adipose tissue allograft model, adipose tissue allografts based on superficial epigastric vessels from Lewis-Brown-Norway rats were allotransplanted into Lewis rats. In the adipose tissue and bone marrow allograft model, combined vascularized bone marrow and adipose tissues were allografted from Brown Norway rats into Lewis rats. The graft survival, the onset and progression of rejection, and the effects of cyclosporine at different dosages and treatment durations were recorded. A rejection grading system was created based on gross observation and was correlated with histologic examinations. RESULTS: Even at a low dose of 2 mg/kg/day, cyclosporine continued to provide effective allograft protection. Tolerance was not observed in either model. Adipose tissue survival after discontinuation of cyclosporine was independent of treatment duration. The inclusion of vascularized bone to the adipose tissue allograft provided an additional protective effect. This effect was synergistic with concomitant use of immunosuppressant. CONCLUSIONS: Adipose tissue allotransplantation is a potential reconstructive option that requires only minimal use of immunosuppressants. Its survival can be further prolonged with simultaneous bone marrow allotransplantation.