While it is theoretically possible that medical and genetic science may eventually result in our ability to engineer and raise pigs that can provide the replacement organs needed to save human lives, is it a realistic and ethical proposition?
The first successful live-human kidney transplant occurred in 1954, the donor and recipient were identical twins. New firsts occurred nearly annually through the 1960s and techniques and procedures have improved since to the extent that human organ transplants are now considered a normal part of the health system. Transplantation is recognized as one of the greatest advances in the medical science of the 20th century, with Dr. Murray who performed that first kidney transplant and Dr. Thomas who pioneered the treatment of leukemia through bone marrow transplants receiving Nobel prizes in 1990. Transplantation's success and widespread acceptance has resulted in an organ demand from patients and surgeons that organ donations are unable to meet. Alternatives to human live and cadaverous organ donations are therefore being sought and xenotransplantation is one of the alternatives being researched.
Sampling of the articles published in the journal Xenotransplantation shows that a significant amount of this research involves the genetic manipulation of pigs to produce organs that are then transplanted into baboons. There are considerable technical difficulties involved in overcoming humeral rejection of these organs and also in researching the risks of cross-species disease spread or the production of new diseases caused by the recombination of human-effective retroviruses with endogenous porcine retroviruses inherent to the transplanted organs; necessitating extensive research experiments.
Manex et al. in 2003, used 23 baboons (Papio anubis) divided into four groups as recipients of pig hearts in their research, the longest surviving baboon died 136 hours after its transplantation operation.
Two of the most common ethical philosophies are deontology that considers whether an action in itself is right or wrong and utilitarianism that judges on a cost/benefit basis - good for the many outweighing harm to the few. From a deontological viewpoint, taking a normally functioning heart out of a baboon and replacing it with a pig's heart that results in the baboon's death within 136 hours would have to be judged wrong. Only from the utilitarian perspective can such an act be justified, but that is dependent on the sacrifice of the "donor" pigs and recipient baboons resulting in significant benefit to others, whether human or not and relatively independent of whether human rights are considered superior to animal rights.
In New Zealand, the Animal Welfare Act 1999 legislates the use of animals for research, testing or teaching on the utilitarian premise, that the benefits from such must outweigh the costs incurred by the animal(s) used. Even if we accept the utilitarian ethos, it still means that for all past, present and future experimentation, impacts detrimental to laboratory animals can only be ethically justified if it results in a biotechnology that is not only viable and functional, but is also actually used.
For arguments sake, let's presume that given sufficient experimentation and study, the technical difficulties can be overcome and risk factors such as cross-species disease spread or the creation of new disease pathogens can be minimized to acceptable levels, and just look at whether such a biotechnology would be utilized. In his review of 35 opinion surveys from 23 countries, Hagelin concluded in 2004 that while there was not overwhelming support for xenotransplantation, opposition to it was reducing over time. It can be presumed that when it comes to the matter of their personal survival, the majority of patients would accept a xenograft, particularly if it was the only available option. However, there are alternatives, both biotechnological and political.
Artificial and bioartificial devices are already being used to extend the lives of humans in clinical situations. Currently this is mostly as organ assist or bridging devices. Such as the artificial left ventricle assist device (LVAD) that helps a failing heart to keep pumping, and the bioartificial external kidney called a renal assist device (RAD) that supports patients suffering acute renal failure, where even a dialysis machine would not be able to.
Development of long-term internal devices for organ replacement, particularly for organs that act as filters and hormone producers, appears to resolve around producing advanced polymer constructs that allow biological support of the encased tissues while obstructing immune system responses from causing rejection situations. An alternative approach is to harvest viable organ tissue from the patient to seed the bioartificial device, thus bypassing the need to suppress immunological responses that might cause rejection.
From a study of journal articles available to this author, the first appears to be more supported than the second. Might this be because the second would not require the recipient to maintain an immunosuppressive drug regime for the rest of their lives, supplied by the pharmaceutical multinationals? It would not surprise me in the slightest if medical research is being directed and funded on the basis of returned profits rather than benefit to the human patients.
The other significant factor affecting the requirement for alternatives to cadaverous and live donations of human organs is the available supply. Many donor organs are considered marginal and are discarded. Using these marginal organs for older patients through alternative recipient lists (ARLs) would increase supply and would seem a sensible utilization of available resources; Luciani et al. in 1992 found that four year survival rates for older patients receiving a marginal heart was 81% compared to 80% for those receiving a normal organ, in effect there was no significant difference.
Another political measure that could increase supply is to change the laws that prohibit the sale of organs. It seems somewhat hypocritical to this author that in a human society that places such value on commercial enterprises, financial remuneration for human organ supply is disallowed. In 1984 the US Congress passed the National Organ Transplant Act that prohibited the sale of organs or tissues. Similar legislation has been effected in most developed nations either prior or since. This imposes an artificial limitation on the availability of both live and in particular cadaverous organs available for transplantation.
Surgeons, medical organizations and pharmaceutical companies producing immunosuppressive drugs are all allowed to profit from transplantation endeavors, but the person or their family that makes it possible for such transplantations to occur in the first place are not allowed any financial benefit. Isn't that a rather hypocritical double standard?
If organ supply became a financially beneficial option for the majority of people in the world who face the economically challenging prospect of providing for their families in the event of their death, in effect a form of life insurance that didn't require financial contribution during their lives, the discrepancy between organ demand and availability might easily disappear. Any fears that such a policy change might result in the deliberate murder of potential donors for financial benefit could be eliminated by the requirement of the provision of educational sessions and provisos to inform on the necessary state of cadavers to provide viable organs for transplantation, prior to the signing of binding agreements. Political endeavors are currently striving to increase donor organs through law changes allowing remuneration in the US.
The use of human organs from involuntary donors such as prisoners receiving the death penalty is another possibility. This is already occurring in China and could therefore eventuate in other countries that carry the death penalty on their books, but such involuntary "donation" would be questionable ethically. Then again, the animals used to supply organs for xenotransplantation are referred to as donors in both the technological articles supplied to journals and most opinion survey questionnaires, a description that has to be questionable at best.
In conclusion, experimentation in xenotransplantation is only ethically justifiable if it will result in a biotechnology that will be both viable and utilized. Technological alternatives are both more advanced and more acceptable ethically. Changes in the political and legal climate might eliminate the need for alternatives to cadaverous human organs. Based on these evaluations, continued experimentation into xenotransplantation cannot be justified ethically and therefore should be discontinued.
Bourque, K., Dague, C., Farrar, D., Harms, K., Tamez, D., Cohn, W., Tuzun, E., Poirier, V. & Frazier, O. (2006). In vivo assessment of a rotary left ventricular assist device-induced pulse in the proximal and distal aorta. Artificial Organs 30(8): 638-642.
Bramstedt, K. (2001) Why an alternate recipient list for heart transplantations is not a form of ageism. New Zealand Bioethics Journal 2(2): 27-31.
California Transplant Donor Network (2005) History of organ and tissue donation.
Dirkes, S. & Kozlowski, C. (2003) Renal assist device therapy for acute renal failure. Nephrology Nursing Journal 30(6): 611-620.
Garner, J. (2004) Tissue engineering in surgery. Surgeon 2(2): 70-78.
Hagelin, J. (2004) Public opinion surveys about xenotransplantation. Xenotransplantation 11: 551-558.
Luciani, G., Livi, U., Faggian, G. & Mazzucco, A. (1992) Clinical results of heart transplantation in recipients over 55 years of age with donors over 40 years of age. Journal of Heart and Lung Transplantation 11: 1177-1183.
Manex, R., Domenech, N., Centeno, A., Lopez-Pelaez, E., Crespo, F., Juffe, A.,
Duthaler, R., Katopodis, A. (2003) Failure to deplete anti-Gala1-3Gal antibodies after pig-to-baboon organ xenotransplantation by immunoaffinity columns containing multiple Gala1-3Gal oligosaccharides. Xenotransplantation (2004) 11: 408-415.
Moon, J., Jeon, H., Meng, W., Akaike, T. & Kang, I. (2005) Morphology and metabolism of hepatocytes microencapsulated with acrylic terpolmer-alginate using gelatin and poly(vinyl alcohol) as extracellular matrices. Journal of Biomaterials Science - Polymer Edition 16(10): 1245-1259.
Satel, S. (2005) The waiting game: the struggle to find organ donors is more difficult with a less-than-generous public policy.