The Xenotransplantation Ethics Debate
Using Animal Organs for Humans
Criticism and concerns about xenotransplantation include risks to the patient and the general public, as well as bioethics issues pertaining to the use of animals for human advancement. Xenotransplantation, the use of animal organs for human transplants, can be viewed from one perspective as a life-saving remedy. Many people need new organs to address potentially chronic conditions, but doctors tend to face organ shortages. There are ethical concerns surrounding this practice stemming from the use of animals as involuntary donors as well as the risks of introducing animal-born diseases to the human population. The use of animal organs in such procedures has been under scrutiny because of such reasons and others since the inception of the idea.
There are safety concerns for whole populations. There is the possibility of infection of an organ recipient by an animal virus. Animal rights issues raise an ethical debate over the topic of xenotransplantation. As a result, many regulatory hurdles must be overcome before xenotransplantation becomes an everyday practice.
What's at Stake?
Transplants of animal organs to humans is obviously performed at the expense of the animal in question. Animal rights advocates believe that sacrificing animals for the benefit of human lives is not morally acceptable, whether for the use of their organs or for research necessary to study the immunological factors that cause organ rejection.
Humans are not without risk in this issue either. The effects that latent animal viruses could have on human organ recipients are not fully understood. Opponents of xenotransplantation fear that these viruses, when introduced into a human system, might cause epidemics of diseases to which we have no immunity and for which we have no readily available cures.
Pigs, for example, are currently the best candidate animal species for culturing organs for humans. These animals are also carriers for a retrovirus called porcine endogenous retrovirus (PERV). The virus has been shown to infect human cells, but the consequences of infection have not yet been determined.
Some opponents of xenotransplantation believe that animals are not the solution. These detractors contend that biotech companies are just looking to make money from their ability to clone animal cells and create genetically modified organisms (GMOs), specifically genetically modified pigs known as "knockouts" that lack the alpha-galactosyl transferase enzyme.
Using animal organs would reduce the length of time many people wait for a suitable organ and would allow transplants to occur while the recipient is still somewhat healthy and better able to tolerate surgery. According to the Department of Health and Human Services, in 2017 there were 34,770 transplants and 115,759 patients on waiting lists in the United States.
It is hoped that injecting donor cells into pig embryos in utero will eliminate the need for immunosuppressant drugs, as they have been shown to make the donor and recipient compatible when tested on pigs and other animals. This means using molecular genetics techniques to create genetically modified (GM) animals, specifically altered to be a match for an individual human recipient. The knockout species would be conceived and raised for the sole purpose of being sacrificed for medicine.
Pigs are a good choice of organ donor because of their short gestation period, rapid growth rate, and size of organs, which match those of humans. Hyperacute rejection (HAR) of organs from Gal-knockout pigs transplanted into baboons was prevented due to the absence of expression of the 1,3-galactosyltransferase gene. Although other immune responses are present, there is hope that similar genetic alterations will be possible to address the issue of HAR in humans.
According to Mohiuddin, ethical issues based on the possibility of a disease spread from animals to humans seem to hold less water than previously thought, since PERV has not been found to infect any humans treated with pig tissues to date, nor have any epidemics arisen from infection of human farm workers involved in handling pigs.
Pigs are very clean and can be raised in exceptionally clean environments if necessary. Pig farms for research on xenotransplantation contain barns fitted with filters for keeping out viruses and bacteria. In the future, if the pigs are raised for human transplants, farm workers would wear masks to prevent exposure of the pigs to human pathogens.
Ethical issues surrounding the use of animal organs for human transplants are threefold. There is the issue of animal rights and the breeding of animals simply for human consumption and medical benefit. Second, some critics believe that xenotransplant technology is just another way for biotech companies to make money. There is a perception that these companies are not concerned with the welfare of the animals or the well-being of mankind because of a presumed disregard for the long-term ramifications of the procedure. Finally, the impact of xenotransplantation on the human race is still unknown. The procedure leaves open the potential for new types of infection to be introduced that might not have immediate cures.
Where It Stands
Experts involved in xenotransplant research seem to dismiss many of the arguments against the technology. According to lead researcher William Beschorner at the University of Nebraska Medical Center in Omaha, the lawsuits that could arise from using xenotransplants before all the risks have been addressed should deter anyone from risking the safety of consumers just to make money.
Ethicist Andrew Jameton, from the Nebraska Medical Center, pointed out that this issue is no different from research in any medical field. Although the desire for recognition and compensation for the cost of research is always a temptation, especially where venture capitalists are involved, "scientists in all fields must guard against letting profit get ahead of scientific method and accuracy." The issue of integrity is no greater in this than in any other field of science and should not necessarily be viewed as a reason to hold back the technology.
None of the medical advances of mankind could have been accomplished without animal experimentation. The fact remains that xenotransplantation is ethically on a whole different level, as even after the technology is established, animals' lives will continuously need to be sacrificed for the lives of human beneficiaries.
- Mohiuddin, M. Clinical xenotransplantation of organs: Why aren’t we there yet? PLOS Med. 4(3):e75. doi:10.1371/journal.pmed.0040075.
- Reeves, B. Animal organs hold promise for humans, designer pigs goal of med center research, and special farm supports research. Lincoln Journal Star online series on Medical Ethics: Tough Choices.