Medicine

The Heart of A Lion? No, A Pig.. The future of animal organ donation. | by Ivy Ostergaard | ILLUMINATION | Jan, 2022

The future of animal organ donation.

Photo by Ali Hajiluyi on Unsplash

N an organ shortage, how can one provide life-saving procedures to 107,000 people on the waiting list? This problem has been eminent since the beginning of organ transplantation, peaking at 124,000 people on the waiting list in 2014. In fact, as of March 2021, approximately ten patients die each day on the US waiting list. To attempt to alleviate this issue, scientists have begun to tackle the organ shortage from the next best thing to humans: animals.

Xenotransplantation:

Xenotransplantation is the general name for this animal-to-human (or vice versa) transplantation process. As described by the FDA, xenotransplantation is

“Any procedure that involves the transplantation, implantation or infusion into a human recipient” of organs, tissues, fluids, etc. that come from a nonhuman source.

To be able to use these nonhuman sources for organs, tissues, etc., scientists have been utilizing genetically-modified animals so that the matter is not rejected or harmful to the human body. A 2000 work by Dr. Marlon F. Levy describes some of the qualifications that an animal should have:

  • compatible anatomy — so that the organ may function well in human physiology. Ex: a heart of a dog would be much too small and therefore not work well.
  • no cross-species infection should be possible. Levy describes that ideally, there should be a resistance to human diseases (Levy, 2000).
  • there needs to be a minimal immunological response to this foreign matter within human physiology so that the transplantation might not be rejected.
  • the animal should be inexpensively bred and raised, as accessibility is already an issue.
  • minimal ethical issues with this specific animal’s consumption. This issue might be more prevalent with primate donors, due to their proximity to our own species. For a great article on the ethics of these practices, check out Erik Reich, DC’s article here.

Pretty cool, right?

Well, unfortunately, there are no animals that truly fulfill all the requirements, making it even more important for careful research and planning to be done when going this route.

The Pig: A Reliable Donor?

An animal highly thought of for this line of work has been the pig. As Dr. Magdalena Hryhorowicz and her co-authors write in their publication, they believe genetically modified pigs are the optimal animal due to a variety of factors. For example, porcine have comparable anatomy to humans, large litters, come in varying sizes, are already used regularly for medicinal purposes.

However, Hryhorowicz et al., warn against the possible immune response and later rejection that the recipient might experience. When the body detects a foreign object, it generally assumes that this matter might be dangerous to you. Therefore, it reacts and tries to kill the matter off, also known as rejection.

To prevent rejection, doctors prescribe medications that will hopefully suppress the immune response. While this might enable someone to maintain transplant viability, immunosuppression can be problematic. For example, when one gets sick, they are at higher risk for severe disease as their body will not respond as well to the attacking virus, bacteria, etc. Therefore, transplantation needs to be carefully evaluated and thought through for one’s own personal lifestyle and disease.

Case Study: Pig Heart In Human Patient

On January 7th, 2022, the first successful pig-to-human heart transplant was conducted. This amazing procedure was performed on a 57-year old male named David Bennett, who unfortunately was diagnosed with terminal heart disease which disabled him from being on the waiting list for a heart transplant.

One week later, on January 14th, Nature magazine published an article on the subject and mentioned that Bennett is alive and doing well in the hospital. He is on several medications which perform the immunosuppressive role as mentioned in the previous section. The pig itself underwent several modifications to be able to serve this role: it had three of its own genes “knocked out” (or silenced) and was inserted with six human genes to better its function.

This first is an incredible feat for scientists and has provided hope for an individual who seemed to have none. I personally believe that this is science and medicine at its finest, when we can begin to solve very real, pertinent issues with technologies discovered and refined over the years.

Future Possibilities

Organ transplantation is not the only possible use for xenotransplantation. Studies have been working on utilizing this technique for numerous reasons:

  • cell transplants — such as replacing B cells in the pancreas for Type 1 Diabetics.
  • skin grafts
  • sone transplants

Conclusions

Does xenotransplantation mean that any human organ or tissue can be replaced with those from other species? Certainly not. Does it mean that we might be able to try a variety of those that are desperately needed? Certainly so.

Xenotransplantation quite literally gives us access to utilize a greater portion of the animal kingdom to enhance and save the lives of our fellow humans. When we cannot rely on the human population due to a lack of availability, we might be able to create alternatives with these new technologies. Great caution and regulation need to be taken in executing these procedures; however, we might be able to aid prognoses initially thought of as a death sentence.

Written by Ivy


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