On the road to clinical xenotransplantation.

In recent years the development of novel immunosuppressive strategies and new lines of engineered pigs have enabled improved xenograft survival in the clinically-relevant pig-to-primate models (especially in islet xenotransplantation). Furthermore, researchers have now developed appropriate biomolecular tools to address rapidly the remaining barriers and render organs from source pigs more "compatible" with man. Efficacy has been the main focus of the research conducted in the last few years. However, other fundamental issues, such as those regarding the physiology, the safety, the ethics and regulatory aspects of xenotransplantation, will need to be addressed satisfactorily prior to proceeding with clinical xenotransplantation trials.