Xenotransplantation unlikely to solve organ shortage in near futureBMJ 2001; 322 doi: https://doi.org/10.1136/bmj.322.7285.510/e (Published 03 March 2001) Cite this as: BMJ 2001;322:510
The possibility that diseases may be introduced into the general population by xenotransplantation cannot be ruled out on the basis of current evidence, a new report from the United Kingdom Xenotransplantation Interim Regulatory Authority has concluded.
Xenotransplantation of whole organs is unlikely to solve the shortage of organs for transplantation in the near future, as originally thought, it says. Long term rejection is still a problem, and cloning and genetic modification techniques to address this are still at an early stage.
The authority's third annual report said that while progress has been made, and research into stem cell therapies to treat neurological disorders, stroke, and diabetes is worth pursuing, “uncertainty about the safety of xenotransplantation continues to be a significant obstacle.”
The report cited data suggesting that porcine endogenous retrovirus can be transmitted across species. And it highlighted concerns about the number of as yet unknown infectious agents that could be transmitted from source animals to human recipients.
“At least five more pig viruses have been identified, and we are not sure how important these are,” commented Herb Sewell, professor of immunology at the University of Nottingham and, until last week, a member of the authority.
“The optimism about solid organ transplants has not been realised,” said Professor Sewell. “The immunological barriers are still to be overcome, and the infection issue is still not resolved.
“But there is real potential for stem cell therapy, especially if we can overcome the supply problem with human tissues.”
He thought that this might be feasible in five years' time. Adult stem cells from human peripheral and cord bloods could be used instead of embryonic stem cells, he said.
Tony Minson, professor of virology at the University of Cambridge, said that the climate for xenotransplantation was not optimal, given concerns about bovine spongiform encephalopathy (BSE), foot and mouth disease, and genetically modified food. But he said: “There is a massive market and a huge need for what it might offer. We may find that some of it doesn't work, but we should not stop the research now.”
The report stated that the authority does not support the wish of campaigning groups to hold a moratorium on clinical trials for xenotransplantation. It calls for further research into the risk of infection spread. “Although alternative therapies are in development, xenotransplantation may still offer the prospect of a viable treatment within a worthwhile timeframe,” it concluded.
According to the UK Transplant Support Service Authority, almost 6000 people are waiting for an organ transplant.
Two further reports on infection surveillance and biosecurity are due to be issued by the United Kingdom Xenotransplantation Interim Regulatory Authority later this month.
The title of report is available from from UKXIRA, Department of Health, Room 420, Wellington House, 133–155 Waterloo Road, London SE1 8UG. Tel: 020 7972 4822. It can be accessed at the authority's website: www.doh.gov.uk/ukxira.htm.