They Put What WHERE!?!

Can you get a genetically modified (also called GMO, standing for genetically modified organism) body part instead of a traditional organ from a donor? The answer now is "potentially." Left with no other medical option, a man who was in heart failure received a GMO pig heart and currently is recovering well post-transplant. Davide Bennett was deemed ineligible for both a conventional human heart transplant and an artificial heart pump. When 57-year-old David Bennett was told his options were essentially "try the GMO pig heart transplant or allow nature to take its course" he elected to have the transplant. 

What are the mechanics behind this? As you probably guessed, while in recent years pigs have been used to grow donor organs, we haven't exactly used a pig organ for an organ transplant to a human being before. Pigs also don't exactly line up as 100% compatible with human organs and the reverse is true as well. In order to make sure the donor heart was not rejected, the genes responsible for the rejection of foreign organs by the human immune system were removed from the donor pig heart. In addition to that, there was a gene removed to prevent excessive pig heart tissue growth and six human genes responsible for immune acceptance were inserted. Of course, this means that Bennett will remain under observation for immune response related complications. Interestingly enough, the US Food and Drug Administration (FDA) did grant emergency authorization for this non-traditional surgery on December 31, 2021. While a whole pig heart has never been used, pig heart valves have been transplanted to people in need of heart valve transplants. As the first in the world surgery of its kind, there is a lot to watch out for including some potential rule changes.

While it is not clear as to why Bennett was not deemed suitable for a traditional heart transplant, we can explain what medical professionals look for in patients who are considered for traditional heart transplants. First and foremost, the patient must meet the need for a transplant with some sort of heart condition that cannot be treated without surgery; a heart transplant is usually the final option when looking at medical issues related to the heart as it is an option that cannot be done with a live donor and has a lot of associated risk. In addition, the ideal patient must not have any underlying pulmonary conditions, is under 70 years of age at the time of consideration for surgery, does not suffer from major psychiatric disorders, is not an active smoker (and if was formerly has been clean for at least 6 months), not an active substance abuser, and not actively fighting an infection just to name a few conditions. More than likely, once the organ shortage is addressed the rules for those who qualify for transplants may become a bit more relaxed.

So, what's next for David Bennett and his new heart? Observation. If this surgery ends up being successful with minimal to no adverse events this could open up an opportunity to help more patients in need of a heart transplant. So far, Bennett is recovering well but that does not mean that his death due to heart failure has been completely prevented, as complications can still occur at any time. In general, life expectancy for those who receive a heart transplant is five years post-surgery. For reference, more than 105,000 people are on the national transplant waiting list and 17 die per day waiting for an organ. It is estimated that around 3,000 to 4,000 of these are people waiting on a heart transplant.

Something to consider is that with the availability of pigs as donors, the whole animal could be with minimal waste. In addition, a pig raised for transplant purposes would need to be raised with its health, both physical and mental, taken into account. Having a need for pigs with higher quality of life could help put in place laws that mandate high quality of life for transplant pigs. The more you know!