On January 7, the first successful xenotransplantation, which is the transplantation of organs or tissues from different species, of a genetically-modified pig heart was performed at the University of Maryland Medical Center (UMMC) on a 57-year-old man, David Bennett

David Bennett had terminal heart failure coupled with an arrhythmia, which is a condition that makes his heart beat abnormally. Unfortunately, Bennett was not able to get on an organ transplant list because according to his medical records he had failed to listen to his doctors and take care of himself. Moreover, an artificial heart pump was out of question due to his arrhythmia. Bennett’s condition didn’t give him much time and he had to stay on a life-supporting ECMO machine to stay alive. While the doctors at UMMC couldn’t offer him a human heart, this made him the perfect candidate for the pig heart. In an article from the University of Maryland Medical School Bennett was quoted saying ““It was either die or do this transplant. I want to live. I know it’s a shot in the dark, but it’s my last choice.” So, considering Bennett’s dire situation the FDA approved emergency authorization for the use of this surgery, despite how experimental it is.

What’s even more important is that the pig heart that was transplanted into Bennett is genetically modified. Some people say that it is this ability to genetically modify organs thanks to tech logical advancements of gene editing tools like CRISPR that have helped xenotransplantations to become even more of a reality. The specific heart that was used underwent 10 genetic modifications, where four pig genes were inactivated and six human genes were inserted. 

 The biggest problem with xenotransplantations is the danger of rejection. The cells in our body are able to recognize what’s foreign, especially when it’s from a different species, due to certain markers on the cell membrane of the pig cells. If the pigs lack the markers that identify it as foreign, then there runs a lower risk of infection.So, of the four pig genes turned off, three of them were the inactivation of marking genes. The last pig gene to be turned off was a growth hormone in order to ensure that the pig heart doesn’t become too big for the recipient. The other added  human genes included, according to Science: anti-inflammatory genes, normal blood coagulation genes, and genes that reduce antibody response.

Two other experimental additions were made. For one, Bennett’s Doctors deemed it vital to be put on a strong and new experimental immunosuppressant by Kiniksa Pharmaceuticals, called KPL-404, in order to lower the risk of infection. Furthermore, the heart has to be prepared in a special solution that requires the heart to be treated with cocaine–forgoing this step results in a malfunctioning heart.

The people who have been leading this operation include Dr. Bartley P. Griffith, one of the main transplant surgeons who operated, and the expert and Director of xenotransplantations at the University of Maryland School of Medicine (UMSOM), Dr. Muhammad M. Mohiuddin. Dr. Mohiuddin was a leading expert in xenotransplantations who was brought into UMSOM to lead operations and programs in that field after successful studies of pig heart transplants in baboons. 

Considering all the precedents set and new conditions mentioned above, it’s unclear how exactly things will go for Bennett, so everything is being taken on a day-by-day basis as he’s being closely observed. However, the surgery was a success, the heart was put in, and Dr.Griffith did say that “It’s [his new heart] [is] functioning beautifully. We are just stunned at how well it’s working.”

This surgery stands on what could be a precipice of change for the organ shortage problem in America and throughout the world. In the US currently, there are 107,000 people waiting on an organ and about 17 people die everyday in wait. While this surgery certainly hasn’t created a permanent fix to the problem and is still shadowed with so much of the unknown, it has opened so many doors that have in return given many on those waiting lists hope.

While this has been one of the biggest medical stepping stones this year, it has still caused a lot of backlash amid ethical concerns regarding the use of pigs. For example, PETA  has gone out to call the use of animal organs as “unethical and dangerous” as well as going on to say how “Animals aren’t tool-sheds to be raided but complex, intelligent beings.” Others argue that so long as only genetically modified pigs are used for the organs and are treated without excess harm. On the other spectrum, there are those who oppose this due to the fact that the pig hearts are genetically engineered.

Xenotransplantation is not a new concept and has been experimented with for years. In fact, early on, it was thought that primates would make a better match for human transplants considering that genetically they were much more alike. However, pigs were seen as a better choice when taking into consideration the risks of getting viruses and other diseases that were previously isolated to primates only. It also looks like pigs are going to make even more headway as the Biotech company that genetically modified the pigs, Revivicor, is planning on building an even larger building to supply more organs.