[Xenografts: clinical trials and perspectives]

Despite the reticence of certain prominent scientists, there will be no moratorium on clinical xenotransplantation in the USA and a limited number of well-controlled trials will be enabled. There has already been some advances in cell and tissue xenografts with encapsulated porcine pancreas cells and porcine foetal neurones in patients with diabetes and Parkinson's disease. However, because of some porcine viruses are able to develop in human tissues, current and planned trials have been interrupted until routine viral detection tests are available. Several attempts have been made in the past, with animal organs (kidney, heart, liver) from various non-human primate species and conventional immunotherapy without success. Another major question now, is the choice of the animal donor species. Phylogenetically dose to man, non-human primates would be a right and logical choice. But, because of their procurement problems, it is likely that most future trials will be conducted with porcine organs from more performant transgenic animals, more powerful immunosuppressors and new therapeutic strategies based on the natural tolerance mechanisms.