Xenotransplantation, the best alternative for organ transplantation?

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LatinAmerican Post | María Fernanda Ramírez Ramos

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Leer en español: Xenotrasplante ¿la mejor alternativa para el trasplante de órganos?

The chances of doing successful organ transplants have advanced in recent years. Learn more about xenotransplantation and its potential.

When speaking of a xenotransplantation, reference is made to the transplantation of organs between different species. In fact, its name comes from the Greek xenos, which means foreigner. It is a technique that has been extensively explored in recent years in order to use organs from animals, such as pigs, to implant them in patients who require them, especially given the pressing need for organs when there are no donors.

In October of last year, a historic event for humanity happened. At a New York University clinic, a group of doctors performed a pig kidney transplant on a brain-dead woman. It was an animal that had been genetically modified in order to increase its compatibility with a human being. The surgeons managed to connect the organ with the patient's blood vessels to verify that there could be compatibility and that the body would not reject it. The procedure was successful, since it worked for 54 hours in which its performance could be monitored.

On the other hand, in January of this year, the first heart transplant from a pig to a person was carried out at the University of Maryland, United States. This patient, a 57-year-old man named David Bennet, passed away on March 8. However, the two months that he lived after the transplant offers a positive perspective on this type of transplant. “Xenotransplantation could potentially save thousands of lives, but it carries a unique set of risks, including the potential to trigger deadly immune responses”; say the researchers at the university.

Challenges of xenotransplantation

During 2021, a group of researchers from the São José do Rio Preto School of Medicine in Brazil carried out tests with pig kidneys. “The results showed an acceptance of porcine xenotransplantation greater than 80% among 50 patients enrolled on the waiting list and 50 liver transplants”, the report states. And it is that in the South American giant in 2019 there were 133,000 patients on hemodialysis, of which 59,850 could have a kidney transplant. However, only 6,000 received such a transplant and 22,000 died while waiting for an organ. The panorama in the rest of the Latin American countries is not different. For example, in Colombia during 2020 and 2021 the lowest transplant rates of the last 15 years were reported, according to information from the Global Observatory of Donations and Transplants.

One of the greatest challenges of this type of transplant is the genetic modification and subsequent breeding of these pigs. This is done so that the human body, specifically the immune system, is able to accept said organ. However, there are already laboratories dedicated to breeding these genetically modified pigs to continue experimentation, such as United Therapeutics or eGenesis.

Likewise, a very rigorous procedure must be carried out to prevent pig retroviruses from developing in the human body. In addition, the pig's own genes are removed and some of the human beings are added so that acceptance is greater. At the moment, the organs are also being conceived to function provisionally while a human organ donation is found. However, the challenge is to develop organs that are fully accepted by the body and are a successful alternative to save the lives of the millions of people who die on the waiting list.

An ethical dilemma

However, despite the obvious virtues for the development of medicine, xenotransplantation also has certain ethical questions, since it involves raising animals and genetically modifying them to donate organs. Likewise, it supposes moral clashes with certain religious positions.

On the other hand, it is also delicate to test in humans. Before the tests had been done with non-human primates, which also poses a bioethical challenge. However, for science to advance, it is necessary to experiment without knowing very well what the results will be. However, David Cooper, a surgeon at Massachusetts General Hospital, told Nature Magazine that "We learn much more from 4 patients than we would from 40 monkeys."