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; from another, it is an inhumane and unethical way to treat animals.
Many people need new organs to address potentially chronic conditions, but doctors and patients face organ shortages. There are ethical concerns surrounding this practice which stem from the use of animals as involuntary donors, and the risks of introducing animal-born diseases to the human population. The use of animal organs in such procedures has been under scrutiny since the inception of the idea.
There are very real safety concerns for human patients—the possibility of infection of an organ recipient by an animal virus. Animal rights are in question—activists raise a valid ethical debate over the topic of xenotransplantation. As a result, many regulatory, ethical, and safety hurdles must be overcome before xenotransplantation becomes an everyday practice.
What's at Stake?
Transplants of animal organs to humans is 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.
The fact remains that there is a shortage of organs for humans that need them. One of the most valid concerns in this debate—if animals are not used to test for human treatments, what can be used in their place? Technology may provide more answers in the future.
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). While the virus has been shown to infect human cells, the consequences of infection have not yet been determined.
Some opponents of xenotransplantation believe that animals are not the solution. These challengers contend that biotech companies are only concerned with making money from their ability to clone animal cells and create genetically modified organisms (GMOs).
The GMOs specifically targeted in the arguments are genetically modified pigs known as "knockouts" that lack the alpha-galactosyl transferase enzyme (known as alpha 1,3-galactosyltransferase)—the organs of these knockout pigs do not have the xenoantigen synthesis ability that causes organ rejection.
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 Health Resources & Services Administration, in 2018 there were 36,528 transplants and over 113,000 patients on waiting lists in the United States in 2019.
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 for organ donors 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 alpha 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.
Ethical issues based on the possibility of a disease spreading from animals may become null, since animals inoculated with PERV preparations have 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 and suits 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 disregard for the long-term ramifications of the procedure—it is not known what can happen in the future if humans with animal organs begin to reproduce, or if there are other long-term consequences.
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 Xenotransplanting Stands
Experts involved in xenotransplant research seem to dismiss many of the arguments against the technology. 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.
There have also been arguments that the issue is no different from research in any medical field. The desire for recognition and compensation at the cost of research is always a temptation, especially where venture capitalists are involved.
Scientists should be vigilant against profit-mongers when scientific methods and accuracy are at stake. 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. This places xenotransplantation on an entirely different level ethically—even after the technology is established, we will still need test subjects. The future may hold some options, but for now, they are limited.
National Center for Biotechnology Information. "Porcine Endogenous Retrovirus (PERV) – Molecular Structure and Replication Strategy in the Context of Retroviral Infection Risk of Human Cells." Accessed Mar. 23, 2020.
National Center for Biotechnology Information. "Production of Alpha 1,3-Galactosyltransferase-Deficient Pigs." Accessed Mar. 23, 2020.
Health Resources & Services Administration. "Organ Donation Statistics." Accessed Mar. 23, 2020.
National Center for Biotechnology Information. "Why Was Perv Not Transmitted During Preclinical and Clinical Xenotransplantation Trials and After Inoculation of Animals?" Accessed Mar. 23, 2020.