The Ethics of Cross-Species Transplantation

Canada is right to hold off on the transplantation of pig tissues and organs into humans until the ethical questions around the practice have been answered.

When it comes to organ and tissue donation, Canadians are amongst the stingiest in the western world. Canada's national rate for donation is only 14 per million population, whereas countries like the United States and Spain are more than double this amount. On average, 20 to 30 per cent of Canadian patients who require a transplant die on waiting lists every year, and the gap between need and availability continues to widen as demand for organs and tissues accelerates. Data from Canadian Blood Services indicates that this demand will increase by 152 per cent over the next two decades, and in all likelihood many more Canadians will die unnecessarily. What makes this particularly tragic is the fact that organ transplantation is wildly successful as a medical intervention with survival rates of 98 per cent for kidneys, 90 per cent for livers, and 85 per cent for hearts. Currently around 4,000 Canadians are on waiting lists for organs, and wait times can be long and variable depending on what province they happen to reside in. This situation has prompted some to suggest that animal to human transplantation might be the answer: but is this truly the right solution?

In the early 20th century several failed experiments on cross-species transplantation were conducted on rabbits, pigs, goats, sheep, and non-human primates. These xenotransplantations resulted in the rapid death of the animals involved due to rejection and other complications. With current advances in biotechnology and anti-rejection drugs – and specifically the successful creation of transgenic (or "humanized") animals – these animal to human transplantations now work, and several individuals have received xenografts including insulin-producing cells from pigs to deal with diseases like diabetes. Many countries have approved clinical trials of xenotransplantation with the United States Food and Drug Administration being an early adopter back in 1996. In late December 2009 Australia joined the club of xeno-nations. In Canada, however, xenotransplantation is prohibited under the Assisted Human Reproduction Act.

In an attempt to understand more fully how Canadians perceived xenotransplantation, results from a public consultation by the Canadian Public Health Association were published in 2001. In this study it was reported that the majority of informed Canadians felt that clinical trials should not proceed, and that lingering concerns existed regarding population-wide health risks, costs, ethical issues, regulatory problems, and the viability of alternatives including "presumed consent" or "opt-out" laws.

On balance, most study participants perceived the risks as outweighing the benefits. As a result of Canada's position on xenotransplantation, some Canadians are now xeno-tourists – they travel to countries like Mexico in a last-ditch attempt to stay alive, or they buy human organs from living "donors" on black markets in developing countries. Clearly, something needs to be done to address these issues.

Xenotransplantation is not the solution for a variety of reasons. First, there are many unanswered questions about the selection of "donor" animals. Since pigs are roughly the size of adult humans – and because they have large litters – considerable research has been conducted on them. That said, there are many risks associated with transplanting pig tissues and organs into humans including very real concerns about introducing new retroviruses into the human population. Although our relationship with the noble pig has been long and multi-faceted, we should not forget that historically devastating viruses have jumped the species barrier, and that pig influenza killed more than 20 million humans throughout the 20th century.

Second, the use of animals for this purpose exposes a slippery slope. Xenotransplantation does not conform to the well-entrenched principles of voluntarism or altruism that have been expected of donors making such a sacrifice. Although some may argue that there is no expectation of this for animals – and that qualms about taking a pig heart are immaterial when many consume bacon for breakfast on a regular basis – where do we draw the line? If we abandon the principles of voluntarism and altruism, why can't we then extract organs from anencephalic infants, brain-dead patients, or even cloned humans?

Third, investing in xenotransplantation is ethically questionable from a health care distribution perspective. Currently, OECD countries including Canada spend 80 times more money on health care than six-sevenths of the remainder of the world. Xenotransplantation will increase this gap even further, and difficult questions arise regarding how we think about health from a global perspective. While many children die every day in the developing world for the lack of a $10 vaccine, can we morally justify the expenditure of hundreds of millions or billions of dollars on xenotranplantation? In short, the ethical issues raised by xenotransplantation are at least as important as the scientific ones. Until we have these answers, Canada should continue its leadership role and stay out of the pig heart market.

Photo: 1949 – The Year of the Ox, by Daniel Lee. Used by permission.