Writer: Ilham Ahmed
Attempts at Xenotransplantation
Xenotransplantation involves transplanting organs from one species to another, including infusing living cells or tissues. This medical procedure commonly replaces human organs and tissues with animal-derived materials. Pigs are often the ideal candidate for performing xenotransplantation in humans as pig organs are the most similar in size and function to human organs. [1] Cross-species transplants have been performed for many decades and generations, from the 1960s till now. Therefore, xenotransplantation procedures have been performed with multiple other species, not only with pigs. Past transplants mainly involved the transfer of organs from such as chimpanzees and baboons. [2] The organs transferred included the heart, liver, kidney, xenografts, etc., however, these transplanted materials were shortly rejected by the immune system. Moreover, immunosuppressive drugs weren’t as effective enough to halt the immune response against the xenografts. [2] As the cross-species transplantations continued, the main obstacle came from the immune response that resulted in xenograft rejection or death. Xenotransplantation could alleviate severe shortages of organs, however, it remains a heavily debated procedure due to ethical concerns and associated risks.
Risks and Controversies
Some bioethical concerns involving xenotransplantation include the rights of animals, allocation of nature of organisms, social values, death taboo, medical ignorance, etc. These bioethical concerns are usually brought up by human and animal rights activists, politicians, and religious beliefs and traditions that do not see the opportunities and progression of society that come with biotechnological advancement. Critics also disapprove of how this disrupts the nature of living organisms that were made to function a certain way and live a certain period by allowing humanity to “play God”. [3] Animal rights and human dignity concerns have been the most difficult to address, as the success of xenotransplantation could potentially begin the systematic breeding and killing of animals to save human lives. [4] Moreover, many religious beliefs regard humans as possessing higher dignity, so the idea of inserting animal parts into human bodies to preserve life contradicts human dignity. [4] Xenotransplantation is seen as an unusual treatment, though it is highly beneficial if organ supply cannot meet the demand, it violates many cultural and societal beliefs, thus leading to ignorance towards lots of other medical treatments.
Universities, bioengineers, transplant surgeons, public health, the World Health Organization, and multiple other scientists who work in biotechnology and the biomedical field have a stake in making more discoveries about the field of transplantation biology, especially animal-to-human xenotransplantation. More knowledge about xenotransplantation and xenografting will help doctors perform more organ transplants and make it accessible for waitlisted patients. However, public skepticism and negative attitudes could deter the acceptance of xenotransplantation despite successful procedures and treatment methods. For example, animal rights and welfare activists may argue that it is an exploitation of animals to make modifications and harvest their organs to preserve human life. [5] Meanwhile, patients in critical or life-threatening conditions may feel compelled to accept the medical procedure as a last resort due to a shortage of human organs. [6]
Medical Roadblocks
Organ Transplant Reject
After the organ transplant has been a success, transplant failure can still occur as the immune system overreacts to the foreign organ since it contains a different genetic code and recognizes it as a non-self-invader. Even transplanted organ tissues, known as xenografts are short-lived due to preformed antibodies in the blood that immediately reject and destroy the graft within a few hours. [7] To prevent organ rejection, researchers genetically modify the animal organ’s DNA to be similar to the human recipient's genetic code to increase the long-term effectiveness of the organ. [8]
Immunosuppressive Drug Effectiveness
If the transplant is a success and no organ rejection has occurred yet, immunosuppressive drugs are used to reduce the chances of transplant failure. However, this does come with other negative side effects; the patient will need to take them for a long time to ensure that the organ successfully functions within the body. These drugs can also increase the risks of developing multiple other negative side effects that include cancer and toxicity. [7] Since the purpose of these medications is to repress or weaken the immune system’s response to foreign invaders, this increases the risk of bacterial, viral, or fungal infections and susceptibility to developing cancer. [9]
Risk of Zoonotic Diseases
The transmission of viral diseases from animals to humans is a significant concern in xenotransplantation even when animal organs have been genetically edited to remove defects in the gene. There is always a possibility of unforeseen infections or zoonotic pathogens in xenotransplantation. For example, pigs carry various diseases and other porcine endogenous retroviruses (PERVs) that can infect human cells. [10] While some viruses can be removed through robust screening and monitoring, others can remain dormant and cause re-infection, thus raising concern for pig-to-human xenotransplantation. [10]
Longevity of Transplanted Organs
The longevity of transplanted organs and xenografts is a concern in xenotransplantation because it involves transplantation between two species from different lifestyles and environments. In the case of pig-to-human xenotransplantation, it's important to note that the average lifespan of a pig is 15 - 20 years, while a human’s lifespan is around 80 years. [11] This raises a concern for the viability of transplanted porcine organs in human bodies, as it is uncertain whether or not the organ continues to function beyond the expected lifespan of a pig. For example, in a recent experimental procedure in 2022, an elderly patient with heart failure received a porcine heart transplant as a last resort. The patient only survived for two months with a functioning porcine heart. [12]
Final Reflection
Xenotransplantation can be a viable option soon as an alternative to allotransplantation for shortage of human organs. However, it is also crucial to continue researching the risks and harms associated with the procedure, and to provide safe and effective immunosuppressants. Ethical concerns and public attitudes must also be evaluated in the decision-making and addressed through ethical practices, rigorous safety protocol, and informing the public about advancements so that xenotransplantation is moved to a broader clinical application.
Sources & Works Cited
[1] Loike, J. D., & Kadish, A. (2018). Ethical rejections of xenotransplantation? EMBO Reports, 19(8). https://doi.org/10.15252/embr.201846337
[2] Cooper, D. K. C., Ekser, B., & Tector, A. J. (2015). A brief history of clinical xenotransplantation. International journal of surgery (London, England), 23(Pt B), 205–210. https://doi.org/10.1016/j.ijsu.2015.06.060
[3] Liang, T. (2023, October 11). Ethical, theological, and social considerations of xenotransplantation — Science ReWired. Science ReWired. https://www.sciencerewired.ca/biology-medicine/ethical-theological-and-social-considerations-of-xenotransplantation
[4] Shaw, D., Dondorp, W., & De Wert, G. (2018). Ethical issues surrounding the transplantation of organs from animals into humans. Revue scientifique et technique (International Office of Epizootics), 37(1), 123–129. https://doi.org/10.20506/rst.37.1.2745
[5] Rollin B. E. (2020). Ethical and Societal Issues Occasioned by Xenotransplantation. Animals : an open access journal from MDPI, 10(9), 1695. https://doi.org/10.3390/ani10091695
[6] Syd, L., & Johnson, M. (2022, January 19). Xenotransplantation: three areas of concern. The Hastings Center. https://www.thehastingscenter.org/xenotransplantation-three-areas-of-concern/?utm_source=chatgpt.com
[7] Carrier, A. N., Verma, A., Mohiuddin, M., Pascual, M., Muller, Y. D., Longchamp, A., Bhati, C., Buhler, L. H., Maluf, D. G., & Meier, R. P. H. (2022). Xenotransplantation: A New Era. Frontiers in immunology, 13, 900594. https://doi.org/10.3389/fimmu.2022.900594
[8] NKF Patient Education Team. (2023, January 2). Xenotransplantation - Definition, uses, and effectiveness. National Kidney Foundation. https://www.kidney.org/kidney-topics/xenotransplantation
[9] Richter, L. (2024, May 4). Long-Term use of immunosuppressants: benefits and risks. DarwynHealth. https://www.darwynhealth.com/immune-disorders-and-management/management-of-immune-disorders/treatment-approaches-for-managing-immune-disorders/immunosuppressants-for-immune-disorders/long-term-use-of-immunosuppressants-benefits-and-risks/?lang=en
[10] Boneva, R., & Folks, T. (2004). Xenotransplantation and risks of zoonotic infections. Annals of Medicine, 36(7), 504–517. https://doi.org/10.1080/07853890410018826
[11] Yihy. (2024, February 27). Pig Years to Human Years - Pig Age Calculator - YIHY. Animal Years to Human Years Calculator. https://yearsinhumanyears.com/calculator/pig-years-to-human-years/
[12] Nguyen, M. (2024, November 30). Should we put pig organs in humans? We asked an ethicist. Vox. https://www.vox.com/future-perfect/388544/pig-organ-transplants-xenotransplantation-ethics-consent?utm_source=chatgpt.com
Comments