Where Are We Going

Xenotransplantation: progress and promise

BMJ 1999; 319 doi: http://dx.doi.org/10.1136/bmj.319.7220.1311 (Published 13 November 1999) Cite this as: BMJ 1999;319:1311
  1. Harold Y Vanderpool, professor in history and philosophy of medicine (hvanderp@utmb.edu)a
  1. Institute for the Medical Humanities, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1311, USA

    Extensive research in xenotransplantation is being propelled by the critical shortage of allotransplants. About a third of the patients on organ waiting lists in the United States die for lack of available organs, and in the United Kingdom fewer than 30% of those waiting for kidneys receive them each year.13 The human toll of suffering in patients who need transplants is great, and their quality of life is poor.

    This update focuses on whole organ xenotransplants. It draws on the latest published studies and the assessments at two recent meetings—a conference of US and UK scientists, ethicists, and policy experts in New York in May 1999, and the June 1999 meeting of the xenotransplantation subcommittee of the US Food and Drug Administration's Center for Biologics Evaluation and Research.

    Research is currently being conducted in all the critical areas of xenotransplantation, and this will, it is hoped, make xenotransplants safe and effective for human beings. These critical areas include immunological barriers, physiological functioning, infectious disease risks, and pivotal ethical issues.

    Summary points

    Xenotransplantation research is driven by the acute shortage of available allotransplants

    Although one longstanding problem, hyperacute rejection of xenotransplants, is being overcome, daunting immunological barriers remain

    Great attention must be given to the physiological functions of porcine organs in human beings

    Worries over the infectious disease potential of porcine xenotransplants are easing

    Ethical concerns over xenotransplants, including the challenge of identifying patients who might be approached as subjects of reinitiated clinical trials, are being explored

    Immunological barriers

    Over time, xenotransplantation has proved to be daunting because of organ rejection. Rejection occurs in several stages: hyperacute rejection, acute vascular rejection, cellular rejection, and chronic rejection.24 Hyperacute rejection and acute vascular rejection are mediated by antibodies against oligosaccharide determinants on pig vascular endotelium.5 These forms of rejection occur …

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