This Little Piggy: Should the Xeno-Pig Make It to Market? Xenotransplantation is the transfer of…
This Little Piggy: Should the Xeno-Pig Make It to Market? Xenotransplantation is the transfer of…
This Little Piggy: Should the Xeno-Pig Make It to Market?
Xenotransplantation is the transfer of living cells, tissue, and organs from one species to another, such as from a pig to a human for medical purposes. The transplanted material is called axenotransplantand is the technological base upon which the xenotransplant industry is built.
The history of xenotransplantation dates back to the first transplant of a pig kidney into a human in 1906. Other experiments have included kidneys transplanted from goats, sheep, and chimpanzees; livers and bone marrow from baboons; and hearts and skin from pigs. In one of the field’s earliest efforts, a California baby lived for three weeks with a heart transplanted from a baboon.1
BENEFITS TO ORGAN FARMING
There are many anticipated benefits to organ and tissue transplants, including extended life expectancy and improvement of the quality of life. A severe shortage of human organs and tissue, however, has created keen interest in alternatives that might make up for this shortfall. This makes xenotransplantation, with its potentially“unlimited source”of organs and tissue, a very attractive alternative indeed.2Since the first organ transplant was performed more than fifty years ago, there have never been enough human donors to meet the demand. The United Network for Organ Sharing reported that, as of 2006, 16,445 transplant surgeries had been performed, but 95,919 patients remained on the waiting list.3Any diseasecurrently treated by human-to-human transplants (e.g., diabetes, liver failure, Parkinson’s disease, cancer, and AIDS) could potentially be treated by xenotransplantation, even though xenotransplantation, particularly the whole organ transplants involving baboon and chimpanzee hearts, has yet to achieve more than limited success. Researchers in New Zealand found that a technique they developed to transplant pig cells into diabetics also may hold promise for people who suffer from brain injuries or strokes. While still in the experimental stage, the research showed that transplanting brain cells into stroke-injured rats reduced their brain damage by 40 percent.4New Zealand has evolved into a center for xenotransplantation research since the New Zealand BioEthics Committee recommended that xenotransplantation be permitted on a case-bycase basis. The resultant increase in people traveling to the area for surgery has led to a new term:“xenotourism.”5
WHY PIGS?
Pigs make a good choice because their organs are an appropriate size for adult patients. Plus, pigs have large litters, grow to adulthood quickly, are relatively easy to breed, and can be raised in sterile environments. Although organs from animals closest to human beings are less susceptible to immune system rejection, nonhuman primates like apes and monkey are limited in number, costly to raise, and are relatively slow to mature. Another problem with primates is that they may harbor unknown viruses that do them no harm but that may lead to devastating diseases in humans. This happens because viruses can cross the species barrier, and this technique is especially risky with nonhuman primates. It can happen with other species as well, however, and it is made more likely when living organs are placed directly into the human body. Pathogens (organisms that cause disease, such as viruses or bacteria) bypass skin and gastrointestinal tract defenses, which, in turn, trigger a response from the immune system.
PROBLEMS AND CONCERNS
Immunosuppressant drugs manage the immune system reaction fairly well in human-to-human transplants, but this rejection becomes increasingly violent in more distantly related species and requires higher-strength immunosuppressant drugs. PERV (Porcine Endogenous Retro-Virus) can infect human cells in the laboratory, supporting the belief that the same may occur with transplant recipients. Parts of pig retroviruses may also recombine with parts of human viruses to create a new virus. This effect has also been observed in the lab.6One suggested solution to the PERV problem is the use of cloning technology. This would provide consistent groups of donor organs that prevent rejection while providing a known retrovirus-free organ to the donor; this approach may take several years to develop. One of the biggest issues surrounds the fact that“to get to the point where surgeons will be good at transferring organs from pigs into humans, they will need to trial on primates. And the use of primates is rightly considered a last resort,”Michael Banner, chair of the British government’s animal procedures committee, told theLondon Times. One of the reasons for this, says Banner, is the rich social and mental life primates possess“and because they are our cousins, people rightly feel that the use of primates is of more concern than the use of other species.”7
Genetic engineering would increase the number of animals used because they would be cloned specifically for research.“Scientists are sometimes too willing to overlook these issues’ethical implications,”says Banner.“To suppose that how the public reacts to these new technologies is simply a matter of unfamiliarity is patronizing.
Often, people’s unease can be spelt out perfectly coherently.”8
THE FUTURE
For some companies, the future of xenotransplantation seems bright and its rewards not so distant. In 2007, Living Cell Technologies (LCT) announced that they had successfully transplanted the first of six type 1 diabetes patients with their DiabeCell pig implant and that they hoped to commercialize the product for general use by 2012. LCT CEO Dr. Paul Tan said,“This transplant launches LCT’s lead product into the clinic and moves the Company into a phase for growth in the value of our business.”9
Questions for Discussion
1. Should companies be allowed to continue research and development in xenotransplantation? Do the benefits outweigh the risks?
2. Does xenotransplantation threaten the quality of human life? If so, what threats exist? Do similar threats exist for other species?Are quality-of-life issues less important for some species than for others? What, if anything, makes animal rights different from human rights?
3. What threats does xenotransplantation hold for the environment as a whole? Who are the different stakeholders involved? What are their stakes?
4. Given that many countries do not restrict human xenotransplantation, what threats exist globally with xenotransplant technology?
5. Is the issue more or less complicated than other bioethical topics like cloning or stem cell research? How can one make the argument that therapeutic cloning, such as that used in xenotransplantation, should be permittedwhile reproductive cloning, like that advocated by groups like the Raelians (see Chapter 9), should not?
Case Endnotes
1. Anthony Browne,“When Science Makes a Pig’s Ear of It; You Think There Should Be a Big Public Debate About Transplanting Animal Organs into Humans? Don’t Be Silly; Profits Are at Stake,” New Statesman(November 15, 1999).
2. Canadian Corporate Newswire,“Canadian Public Health Association Seeks Opinions of Canadians on Xenotransplantation: Xeno Web Site Launched at http://www.xeno .cpha.ca”(December 13, 2000).
3.“Online Extra: Side of Valves,Hold the Bacon,”BusinessWeek Online(January 11, 2006), 14.
4. Simon Collins,“Cell Transplants Offer Stroke Victims Hope,”New Zealand Herald(July 19, 2004), biotech.com.
5. Peter De Luca,“Xenotourism: Will Your Next Trip Overseas Be for a New Kidney?”Institute of Public Affairs Review(July 2006), 12–13.
6.“The Regeneration Game,”Chemist & Druggist(March 4, 2000).
7. Alison Goddard, interview with Michael Banner,“The Heart of the Debate,” Times Higher Education Supplement(September 18, 1998).
8.Ibid.
9. Company Announcement,“Diabetes Patient Successfully Transplanted in World-first DiabeCell Trial,” Living Cell Technologies Ltd., June 14, 2007, www.lctglobal.com.
