10 - Endogenous retroviruses and xenotransplantation

Summary

THE PROMISE OF XENOTRANSPLANTATION

Every year, thousands of patients with chronic endstage organ failure will die while on the waiting lists for potentially life-saving transplant surgery. Many others will not even make the waiting lists, as they are judged less likely to benefit from scarce human organs. The transplantation of foetal neural cells or foetal islets shows great potential for the treatment of individuals with Parkinson's disease or Type I diabetes, but again the number of potential beneficiaries from such therapies is limited by the availability of donor tissue.

Over the years, such shortages have prompted a number of investigators to explore the possibility of using non-human sources of organs and cells for transplantation into humans. Until now, such efforts have met with little success, but a number of recent developments in biomedical science have appeared to confirm the potential of such approaches (Cooper & Lanza, 2000). Over the coming years, such efforts are likely to become much more frequent as increasing numbers of physicians and surgeons seek to tap into the potential of techniques involving the transplantation of cells, tissues or whole organs from other species into humans, procedures collectively known as xenotransplantation.

SOURCE ANIMALS FOR XENOTRANSPLANTATION

To date, most animal to human xenotransplantation protocols have featured the use of non-human primates as source animals because the close evolutionary relationship to humans might be expected to minimize problems of rejection and to maximize the probability of physiological compatibility between graft and recipient. However, opinion has now turned firmly against the use of non-human primates, partly on ethical and partly on practical and safety grounds (see US Food and Drug Administration Guidance Notice at http://www.fda.gov/cber/gdlns/xenoprim.txt).