Genetic modification of pigs for solid organ xenotransplantation.

Xenotransplantation of solid organs will only ever become a clinical reality with genetic modification of the pig, which is now widely accepted as the most likely donor species for humans. The understanding of the barriers to xenotransplantation has required advances in genetic technologies to resolve these problems. Hyperacute rejection has been overcome by overexpression of complement regulatory proteins or targeted disruption of the enzyme associated with the major carbohydrate xenoantigen. The subsequent barriers of disordered coagulation, induced antibody, and cell-mediated rejection remain challenging. The mechanisms for these incompatibilities are being deciphered, and multiple genetic manipulations to resolve these issues are currently in progress. Moreover, new technologies offer help to producing sizeable numbers of modified pigs in a timely manner. This article retraces the basis and foreshadows progress of the genetically modified pig for xenotransplantation as it advances toward the clinic.