Pig's Heart: Cautious optimism
For the first time, a human was transplanted with the heart of a genetically modified pig
Daria Sarkisyan, Meduza
On January 7, 2022, 57-year-old David Bennett from Maryland (USA) was transplanted the heart of a genetically modified pig. This was the first such operation. On the evening of January 10, the patient was alive, his new heart was working, and there was no other news yet.
Bennett's heart was not performing its function well, and the patient needed a donor organ. However, he could not get on the waiting list to receive a heart from a person with brain death, because he was in too bad a condition for this (in a press release The University of Maryland Medical Center says that this was also confirmed by specialists from other medical organizations). Because of the arrhythmia, Bennett also could not claim a temporary measure — a mechanical device that partially performs the function of the heart. Then doctors at the University of Maryland Medical Center offered him a heart transplant from a genetically modified pig. The patient had no alternatives that would prolong his life, so he agreed.
Transplantation of organs and tissues of animals to humans has both pros and cons
People in need of a donor organ do not always live to be transplanted. The quality of life of the rest is often low due to a serious illness. For example, in Russia in 2020, 708 people were on the waiting list for a donor heart. 53 of them died, 251 people received an organ, the rest remain on the waiting list for surgery.
Some other organs can be taken from living donors, but for various reasons it is not always possible to do this. Therefore, experts are looking for alternative options.
One of the possible ways is xenotransplantation, that is, organ transplantation from a representative of one animal species to another. At the moment, xenotransplantation from genetically modified animals in theory makes it possible to cope with several causes of organ rejection - a big problem of transplantology. The patient's immune system attacks the donor organ, which may cause it to stop working. Therefore, donors and recipients are checked for histocompatibility, and then the patient takes drugs that suppress the immune system for life.
Thanks to the genetic modification of the pig, it was possible to avoid a hyperacute reaction of rejection of the heart in David Bennett. The donor was an animal with a modification in ten genes: four genes were "turned off", including one that was responsible for the growth of the heart (so that the organ did not start growing inside the patient), and six human genes were added so that the recipient's immune system better accepted the new heart.
But it is possible to develop other types of rejection, including those that are not affected by the gene modification applied here. Therefore, Bennett receives conventional drugs that suppress the work of the immune system, as well as a new drug developed with the participation of researchers involved in xenotransplantation.
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