I imagine most of you have heard that earlier this year a genetically modified pig heart was transplanted into a human for the first time. You did not know? Stay! We are going to tell you everything.
I put you in context
On January 7, the first heart transplant from a genetically modified pig to a human being was performed, just one week after the FDA (US Food and Drug Administration) authorized this experimental operation.
This was a project that cardiothoracic surgeons Bartley Griffith and Muhammad M. Mohiuddin, directors of the Cardiac Xenotransplantation Program at the Maryland College of Medicine (Baltimore), had been working on for several years. And finally, on New Year’s Eve 2022, his dream came true, his project was to be realized in a human being.
The human in question was David Bennett, a 57-year-old man from Maryland with end-stage heart failure. The man was facing certain death , since he had already been bedridden for about two months depending on a machine that performed the function of his heart, since his was no longer compatible with life. The problem was that, due to his medical history, he was not eligible for a human transplant, since he was a person who used to not follow the medical instructions correctly, something very important in transplant candidates. Therefore, the FDA authorized the operation only as “compassionate use”, when faced with a life or death situation.
Why a genetically modified pig?
I don’t know if you have noticed, but we have always talked about a genetically modified pig’s heart. It is important that it was “genetically modified” because, although these animals are the favorites when it comes to xenotransplantation (transplantation between animals of different species) in humans because their circulatory system and organs are quite similar, they also have some genes that are incompatible with those Humans.
For this reason, they eliminated the pig genes that trigger hyperacute rejection, the one that occurs almost immediately after surgery, and added human genes to help the body accept the organ. Among the genetic modifications, they also made sure that the heart would not grow larger once transplanted.
Although it may surprise you, pigs have been used in modern medicine for a long time, what’s more, numerous pig skin transplants have been carried out on humans, and even heart valves (those valves that you studied in biology during your childhood, the tricuspid, the mitral and crescents). But using whole organs, instead of pieces of tissue, is another story.
It should be noted as a curiosity that the pigs used, both during the experiments and during the transplant, were provided by the same biotechnology company that cloned and bred Dolly the sheep, the first mammal cloned from an adult cell.
Before transplant
It may seem that human organ transplants are completely different compared to pig (and other animal) transplants, but the problem of rejection is something that can happen in either case. It is your own body that decides what is foreign and what is your own. Your body simply detects that something is wrong, and just as it attacks viruses and bacteria, it attacks the new organ, wherever it comes from.
But then, what is it that led the FDA to approve this type of transplant, if it had never been done before? As we have already said, it was a matter of life or death, since David was in such poor condition and without the option of a human heart, if it was not treated he would die. But not only that, it is suspected that what also persuaded the FDA to allow it was that the same surgeon who was going to operate on David, Dr Mohiuddin, had successfully performed numerous pig heart transplants on baboons.
Of course, in order to carry out the transplant, in addition to being informed about the risks, David had to be evaluated by several psychiatrists who ensured that he was in full mental capacity to consent to the intervention.
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postoperative
This transplant was a pioneering procedure in which not only pig tissues were transplanted, but also a complete and functional organ.
After the operation, as we have said before, it is very important to follow the doctor’s instructions in order to avoid rejection and possible infections that may appear. Immunosuppressants , for their part, would cover the part of avoiding rejection of the organ, since by lowering the person’s immunity, we reduce the probability that the body will attack the new organ as if it were something alien to it. But when immunity is lowered to prevent rejection, it is also lowered for other problems, and the person becomes more susceptible to infections. Fortunately, David managed to overcome these obstacles.
Initially, the transplant was considered a success. To our knowledge, the heart functioned well at all times and there were no signs of rejection for weeks. The problem came a few days after doing the two months of the transplant, as David began to deteriorate progressively, and in a week he had died.
Death
David Bennett passed away on March 8 at the University of Maryland Medical Center, two months and one day after his famous transplant.
The causes of death are still unclear, as his body did not show signs of organ rejection at any time. The only thing that is known so far is that days before his death, the patient began to deteriorate, but a thorough examination is being carried out, and they hope to be able to publish the results soon.
Of course, despite David’s death, this transplant is considered an important advance for science related to medicine , since the pig’s heart was not immediately rejected and continued to function for more than a month and a half without apparent problems. . This is a critical milestone for patients requiring transplants.
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References:
A man who got the 1st pig heart transplant has died after 2 months. (2022, 9 de marzo). NPR. https://www.npr.org/2022/03/09/1085420836/pig-heart-transplant?t=1647255397786
Galchen, R. (2022, 28 de Febrero). The Medical Miracle of a Pig’s Heart in a Human Body. The New Yorker: Annals of Medicine. https://www.newyorker.com/magazine/2022/02/28/the-medical-miracle-of-a-pigs-heart-transplant-in-a-human-body
‌ Macrovector (s.f.). Isometric surgeon doctor background with composition of text and people performing surgical operation with modern equipment Free Vector [Imagen]. Flickr. https://www.freepik.com/macrovector
Man given genetically modified pig heart dies. (2022, March 9). BBC News. https://www.bbc.com/news/health-60681493
Rabin, R.C. (2022, 9 de marzo). Patient in Groundbreaking Heart Transplant Dies. The New York Times. https://www.nytimes.com/2022/03/09/health/heart-transplant-pig-bennett.html
Reardon, S. (2022). First pig-to-human heart transplant: what can scientists learn? Nature, 601(7893), 305–306. https://doi.org/10.1038/d41586-022-00111-9
Salam, E. (2022, 9 de marzo). First person to receive heart transplant from pig dies, says Maryland hospital. The Guardian; The Guardian. https://www.theguardian.com/us-news/2022/mar/09/first-person-heart-transplant-pig-dies-david-bennett
Schaffer, R. (2022, 9 de Marzo). First human recipient of genetically modified pig heart dies. Healio. https://www.healio.com/news/cardiology/20220111/genetically-modified-pig-heart-transplanted-into-human-for-first-time
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