ABSTRACT
The capacity of pluripotent human stem cells to differentiate into diverse functional cell types has generated excitement about their potential use as a source of cells for transplantation in the treatment of a wide range of diseases. However, their exogenous origin confers upon pluripotent stem cells a status comparable to that of unrelated organ donors. Graft rejection is triggered by the recognition of antigens on the cell surface of the transplanted tissues. These 'transplantation' or histocompatibility antigens are the result of genetic polymorphism in the human population creating antigenic differences between the donor and recipient. Minor histocompatibility antigens represent a further immunological barrier to successful transplantation. In sum, the strategies available for coping with immunity appear to be sufficiently diverse and robust to justify the claim that pluripotent stem cells and their derivatives offer new solutions to the longstanding challenge of matching exogenous, transplantable tissues to their intended recipients.
