Advances in the development of experimental composite tissue transplantation models

The preclinical experimental models of composite tissue allograft (CTA) have rapidly developed in the past years. When microsurgical techniques were established, researchers focused on immunomodulatory protocols that overcome the immunologic barrier between the allogenic donor and recipient. To test immunologic response, functional recovery, and technical feasibility, experimental CTA has been performed in different models, including rodents, large animals, and nonhuman primates. In the experimental studies, researchers are focused on tolerance-inducing strategies based on immunosuppressive protocols allowing for widespread application in the clinic. In this review, authors analyzed the current knowledge of immunologic aspects and tolerance-inducing strategies in CTA experimental models, including single components such as skin or vascularized bone allograft versus CTA containing multiple tissues such as experimental limb and face transplants, and emphasized their relevance and applicability to the clinical scenario.