Xenotransplantation: Animal to Human Transplants
Tens of people die every day waiting for an organ transplant, and organ donations are not enough to cover the need. Not to forget that, organ donation has many barriers; be the financial incentives, molarity, and the ethical side that considers the differentiation of death and brain death; but most of all: organ shortage.
To start, the first thing we should know is how a transplant works and what its purpose is.
When an organ or tissue is damaged or is missing completely, a graft is transplanted to make up for its absence. Thus, a graft is a substitute for the original organ or tissue which is ought to adapt to the new system and surroundings to continue its function in the system. Grafts are divided into categories based on their origins. We will discuss xenograft or xenotransplant that cover tissue and organs transplanted from an animal into a human.
Currently, the animal species that are considered biologically the best match in terms of similarity for xenotransplantation is the domestic pig because of the similarity of the function and size of domestic pigs’ organs and human organs, the ability to breed them to high health standards by microbiological environmental monitoring, and their fast maturing period. On the other hand, apes and monkeys which seem like the most logical option proved to be not that accessible since they require more time to breed and provide fewer offspring, just like humans. In addition to that, similarities that we usually value, create a greater chance of the spread of diseases after the transplant, regardless of the rejection rate of organs. Compared to domestic pigs; apes and monkeys are far more feral and usually reside in environments that cannot be controlled as was in domesticated pigs. It is more arduous to manipulate the microbiological condition of the environment, thus they have lower health standards, causing primates such as monkeys and apes to be less desirable for xenotransplantation.
The duration and aftermath of xenotransplantation are a challenge in themselves. Unlike human-to-human transplants, in which there is less risk of a human’s immune system accepting the donated organ, we come across hyperacute rejection in xenotransplantation since the transplanted tissue is non-human. To overcome this, pig eggs that are fertilized are injected with small amounts of DNA that imitate human gene sequences.
In the light of this founding and research, a man named David Bennet has become the first person ever to receive a heart transplant from a pig. Yet, he passed away two months after the transplant and the actual cause of his death was not announced. Even though Mr. Bennet has unfortunately passed away, it was stated that this transplant has assisted in proving that a genetically modified pig heart is able to function if the immune system of the person is well controlled.
Now, besides xenotransplanted tissues, an entire organ has been xenotransplanted with success. Maybe in the following years, we will be able to get through the obstacle of organ shortage, and thousands and thousands of people waiting to get an organ donation will be spared the years of waiting without certainties. And maybe, in the near future, we will be looking at domestic pigs and see a future with fewer obstacles ahead.
Works Cited
Bates, Mary. “Overcoming Challenges in Organ Transplantation.” EMBS, https://www.embs.org/pulse/articles/overcoming-challenges-in-organ-transplantation/.
Libretexts. “19.3: Organ Transplantation and Rejection.” Biology LibreTexts, Libretexts, 5 Mar. 2022, https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(OpenStax)/19%3A_Diseases_of_the_Immune_System/19.03%3A_Organ_Transplantation_and_Rejection.
“Xenotransplantation: The Benefits and Risks of Special Organ Transplantation.” BIO, https://archive.bio.org/articles/xenotransplantation-benefits-and-risks-special-organ-transplantation#:~:text=Appropriate%20Animals%20for%20Use%20in%20Xenotransplantation&text=Pigs%20are%20preferred%20because%20they,standards%20in%20microbiologically%20controlled%20environments.
Hryhorowicz, Magdalena, et al. “Genetically Modified Pigs as Organ Donors for Xenotransplantation.” Molecular Biotechnology, Springer US, Oct. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617878/#:~:text=Therefore%2C%20genetically%20modified%20pigs%20can,genome%20in%20virtually%20unlimited%20ways.
Press, The Associated. “A Man Who Got the 1st Pig Heart Transplant Has Died after 2 Months.” NPR, NPR, 9 Mar. 2022, https://www.npr.org/2022/03/09/1085420836/pig-heart-transplant.
