Xenotransplantation for CNS repair: immunological barriers and strategies to overcome them

Neural transplantation holds promise for focal CNS repair. Owing to the sho rtage of human donor material, which is derived from aborted embryos, and e thical concerns over its use, animal donor tissue is now considered an appr opriate alternative, In the USA, individuals suffering from Parkinson's dis ease, Huntington's disease, focal epilepsy or stroke have already received neural grafts from pig embryos. However, in animal models, neural tissue tr ansplanted between species is usually promptly rejected, even when implante d in the brain. Some of the immunological mechanisms that underlie neural x enograft rejection have recently been elucidated, but others remain to be d etermined and controlled before individuals with neurological disorders can benefit from xenotransplantation.