Who’s afraid of xenotransplantation?
Using pig organs in humans could save thousands of lives. So why is Britain driving research away?
Seven years ago I wrote an article for spiked stating that the American and British authorities were ‘moving towards approval of small-scale human trials of xenotransplantation and their efforts need applause and encouragement’ (1). It seems the British have not clapped loudly enough. Last month, Professor Lord Robert Winston, medical academic and researcher of the human reproductive system, announced that he was finally throwing in the towel and moving his xenotransplantation efforts to California (2,3).
Xenotransplantation involves grafting animal cells and tissues into humans and it is the only hope of survival for many people needing a new heart, liver, kidney and so forth. Every year, almost 10 per cent of people awaiting a heart transplant die because no heart is available. This amounts to around 50,000 people a year in America. The numbers are lower in Britain, but over 9,000 Britons currently need a transplant and most of them will be disappointed. Even under ideal donor conditions, the supply of transplantable organs will never meet the demand. Innovative methods of tissue engineering are the only way that a continual loss of life can be avoided and xenotransplantation is especially attractive.
Xenotransplantation promises an almost limitless supply of tissue and organs harvested from specially prepared and genetically modified pigs. Pigs are attractive because of their size, generally matching physiology and ease of breeding. In Winston’s lab they had successfully modified pigs to produce altered sperm to breed a line of more humanised pigs. Modifying the pigs to be genetically more human is an important step in ensuring the human immune system does not reject organs harvested from pigs. Since that success, however, the British and EU governments have banned the mating of genetically modified animals. Even before that ban, it took Winston two years to get a Home Office licence to study six modified pigs.
Most of the concerns about xenotransplantation surround the possibility of viral transmission. Many viral and bacterial dangers can be removed from the pigs with closed breeding, barrier air filters and other strict bio-security measures during preparation. Pigs are potentially a safer source of organs than humans because viruses such as cytomegalovirus and Epstein-Barr virus, a common cause of death in the post-transplant patient, can be removed from pig, but not human, donors.
Breeding or other extraction procedures, however, cannot remove porcine endogenous retrovirus (PERV) because it is integrated into the genome of pigs. Cross-species transmission of viruses is a particularly acute concern as the virus can be devastating to its new, human, host. Examples of cross-species viral transmission include HIV, Ebola and bird flu. It is obviously a good idea to avoid unleashing a new AIDS and so the risk of PERV transmission must be examined carefully.
Almost a decade ago, a team of scientists studied 160 patients, gathered from around the globe, who had received living pig tissue, including skin grafts, blood products and brain tissue (4). No PERV infection was detected in any of the patients, including those placed at greater risk of infection because of immunosuppression. PERV was not detectable in any patient despite the presence of pig cells observed in 23 patients up to eight and a half years after the original procedure. More recently, two immunosuppressed patients with liver failure received blood filtered through a pig liver. Analysis of the patients over a three- to four-year period revealed no evidence of PERV infection (5).
This doesn’t mean that xenotransplantation will be risk-free, but it does imply that small-scale trials with regular checking of the recipients should go ahead. Patients receiving the transplants are taking a definite leap into the unknown, but it is a leap they will likely want to take given the alternative. The risk to the rest of us is hypothetical.
Winston is rightly furious, as he showed in a Radio 4 debate with Baroness Ruth Deech, the former chair of the Human Fertilisation and Embryology Authority, at denying patients that possibility on the most spurious grounds of precaution. The only way that we are ever going to know if xenotransplantation works is if we start doing it – and Winston clearly thinks he is getting close. Rather than embrace this possibility, the British and EU authorities have bound the research with so much red tape that Winston is moving the work almost 6,000 miles west.
Ruth Deech was happy to see the research migrate to America (which she described as ‘a bit of a wild west’) where Winston could work at a safe distance and avoid Britain’s animal rights extremists. What an incredible vision of spinelessness. Instead of embracing the frontier of science, saving lives and facing down a pathetic minority who put pigs before humans, our leaders nitpick, block and shrug until the science moves away.
Stuart Derbyshire is a senior lecturer in psychology at the University of Birmingham.
Previously on spiked
Stuart Derbyshire suggested we need to have the hard arguments in favour of animal research and called for restrictions on stem cell reseach to be lifted. Helene Guldberg looked at why we should take sides in the stem cell wars and was told by Professor John Martin why animal research is justified. James Panton reviewed Adam Wishart’s documentary Monkeys, Rats and Me: Animal Testing. Or read more at spiked issue Animals.
(1) Pig organ transplants: you could die waiting, by Stuart Derbyshire, 9 January 2001
(2) Lord Winston’s fury as red tape drives British GM pig transplant experiments to the U.S., Mail on Sunday, 9 September 2008
(3) Breeding pigs for organ transplants, Today, BBC Radio 4, 8 September 2008
(4) Search for cross-species transmission of porcine endogenous retrovirus in patients treated with living pig tissue, Science, 1999; 285: 1236-1241
(5) Serologic analysis of anti-porcine endogenous retroviruses immune responses in humans after ex vivo transgenic pig liver perfusion, ASAIO Journal, 2003; 49: 407-416
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