Vivian Chen, Grade 10

Healthy organs are vital for every human’s best quality of life. Sometimes, however, organs may become diseased or damaged. When this occurs, the victim may be in need of an organ transplant. Organ transplantation is a process in which an organ is removed from a donor and transplanted into a recipient. Although this is a valid and often successful treatment, it can be difficult for patients to get the organs needed. In the United States alone, over 107,380 people are on the waiting list to receive organs and on each day, twenty-one people on this list die waiting (1).

One solution to this dire issue is xenotransplantation which is the transplantation of organs from a nonhuman donor to a human recipient (2). Pigs are most commonly used as donors for several reasons: they mature rapidly, they give birth to large litters, possess organs whose size and function is comparable to that of humans, and can be bred in microbiologically controlled environments to the healthiest they can be (3).

Xenotransplantation would greatly reduce the number of people waiting on the transplant list which could save many lives. Furthermore, the organs would be much easier to work with in regard to timing. Since there would be so many animal organs available, surgeons would not have to rely on finding a compatible donor and could plan procedures based on what was best for the patient (4).

Nevertheless, this solution is not perfect either which brings up many concerns. For example, there is the possibility of both identified and unidentified infections that could adversely affect the patient (2). Animal pathogens could be transmitted to humans and these pathogens could even adapt to human-to-human transmission (5). The extent of the risk of infection is unknown today, but so far, there has been no evidence of infections caused by porcine xenografts. This does not mean that infection is not possible — there is definitely the potential for it (4). However, with clinical trials and further testing, infections can be prevented through the application of advanced microbiological techniques in the future (6). Additionally, there may be a risk of a more aggressive form of rejection with xenotransplantation compared to human allotransplantation. Rejection of an organ occurs when the recipient’s immune system attacks the donated organ as if it is an infection. Hyperacute rejection occurs after xenotransplantation when the tissue inserted in the body is not recognized as human (3). While a human allograft may be rejected within 5-7 days, a pig xenograft may be rejected within hours and even minutes (7). This risk can be lowered through the breeding of transgenic pigs and cloning. Genetically altered pigs have their DNA modified, causing them to express certain human proteins so the immune system will more easily recognize the organ. Cloning techniques can also be used to reduce hyperacute rejection; the porcine organs with pig genes would be treated the same way as human organs would be by the immune system. With these methods, xenotransplantation would not pose a greater risk as a normal human allotransplantation, and even the same standard immunosuppressive drugs could be used for both (3).

Despite how promising xenotransplantation may seem, it also raises many ethical questions. The first is that transplanted stem cells may mutate into cancer cells. Studies in animals found that implanted embryonic and iPS stem cells can turn into teratomas. This concern, however, may not be completely accurate as more information needs to be uncovered. In 2015, a study was conducted in which patients who received stem cell therapy discovered that the transplanted stem cells displayed no signs of becoming tumorigenic. Secondly, many are concerned that society will spiral downwards, falling into a world of designer babies and genetically modified humans. However, advancements such as in vitro fertilization and preimplantation genetic diagnosis have not been used for eugenic purposes and instead were used to help create healthy babies for parents who are unable to have children naturally. Finally, there are concerns involving animal rights and human dignity. (8).

For instance, xenotransplantation goes against some religions and cultures. In Islam, the use of pig organs to replace failing human organs is prohibited. Notwithstanding, several Muslim scholars have allowed porcine xenografts in the past because the patients would not survive without them. Religions such as Judaism and Catholicism are in favor of xenotransplantation. In Judaism, the ingestion of pig meat is forbidden, but porcine organs can be used for transplants. In fact, xenotransplantation is actually encouraged in order to save the life of someone who is dying of organ failure. Catholic ethicists in the United States and Canada allow xenotransplantation as long as human identity is preserved and aborted embryos are not used as human stem cells (8).

The first procedure involving the transplantation of a pig’s heart into a human occurred in January 2022. Unfortunately, the patient died two months later due to the heart being infected with an animal virus (9). As with any medical development, it takes many years of research and clinical trials. Obviously, this requires extreme dedication often in the face of numerous complications. This setback did not erase the hope that with further research, xenotransplantation could change the future of medicine while saving many lives in the process.

References
[1] Cleveland Clinic. (2021, May 4). Organ Donation and Transplantation: How it works. Retrieved July 9, 2022, from https://my.clevelandclinic.org/health/articles/11750-organ-donation-and-transplantation
[2] US Food and Drug Administration. (2021, March 3). Xenotransplantation | FDA. Retrieved July 9, 2022, from https://www.fda.gov/vaccines-blood-biologics/xenotransplantation
[3] XENOTRANSPLANTATION: The Benefits and Risks of Special Organ Transplantation. (n.d). Biotechnology Innovation Organization. Retrieved July 11, 2022, from https://archive.bio.org/media/press-release/xenotransplantation-benefits-and-risks-special-organ-transplantation.
[4] Boneva, R. S., Folks, T. M., & Chapman, L. E. (2001, January). Infectious Disease Issues in Xenotransplantation. National Library of Medicine, 14(1), 1-14. 10.1128/CMR.14.1.1-14.2001
[5] Boneva, R. S., & Folks, T. M. (2004). Xenotransplantation and risks of zoonotic infections. National Library of Medicine, 36(8), 640. 10.1080/07853890410018826
[6] Fishman, J. A., Scobie, L., & Takeuchi, Y. (2012, April 13). Xenotransplantation-associated infectious risk: a WHO consultation. Wiley Online LIbrary, 19(2), 72-81. https://doi.org/10.1111/j.1399-3089.2012.00693.x
[7] Introduction. (1998). In A. Govaerts, P. Griebel, H. Bazin, & P.-P. Pastoret (Eds.), Handbook of Vertebrate Immunology. Elsevier Science. https://www.sciencedirect.com/topics/medicine-and-dentistry/xenotransplantation
[8] Loike, J. D., & Kadish, A. (2018, July 10). Ethical rejections of xenotransplantation? Embo Reports, (19), e46337. https://doi.org/10.15252/embr.201846337
[9] Pelc, C., & Smiley, J. D. (2022, May 11). Pig heart transplant saves heart disease patient. Medical News Today. https://www.medicalnewstoday.com/articles/first-successful-pig-to-human-heart-transplant-may-offer-new-options-for-patients