The first recipient of a modified pig kidney transplant passed away on Saturday (May 11), around two months after the surgery was carried out.
“We have no indication that it (Slayman’s death) was the result of his recent transplant,” the hospital said in its statement.
For one, the animal organ selected has to undergo genetic modifications, so that the human body does not reject it.
A report from the Harvard Medical School, whose physicians were involved in Slayman’s operation, said 69 genomic edits were made to the pig kidney in his case.
The pig’s anatomical and physiological parameters are similar to that of humans, and the breeding of pigs in farms is widespread and cost-effective.
The first recipient of a modified pig kidney transplant passed away on Saturday (May 11), around two months after the surgery was carried out. The family members of 62-year-old Richard “Rick” Slayman and the Massachusetts General Hospital, where the procedure was performed, did not link the transplant operation to his death.
“We have no indication that it (Slayman’s death) was the result of his recent transplant,” the hospital said in its statement. His family also thanked doctors for their work and said: “Their enormous efforts leading the xenotransplant gave our family seven more weeks with Rick…”
We explain what the procedure is, the promise it holds, and the complications associated with it.
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What is xenotransplantation?
According to the US Food and Drug Administration (FDA), “Xenotransplantation is any procedure that involves the transplantation, implantation or infusion into a human recipient of either (a) live cells, tissues, or organs from a nonhuman animal source, or (b) human body fluids, cells, tissues or organs that have had ex vivo contact with live nonhuman animal cells, tissues or organs.”
Essentially, it is the use of animal cells and organs to heal humans. Xenotransplantation involving the heart was first tried in humans in the 1980s. The need for such a procedure was felt because of the significant gap between the number of transplantations needed by patients and the availability of donor organs.
A 2024 article in Nature notes: “In the United States alone, there are nearly 90,000 people waiting for a kidney transplant, and more than 3,000 people die every year while still waiting.”
The website of Columbia University’s Department of Surgery also points to evidence of neurodegenerative disorders and diabetes being treated with the help of animal cells and tissues.
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How does xenotransplantation happen?
In 2023, Dr. Robert Montgomery, the chief of New York University Langone’s Transplant Institute, told Associated Press that sewing a pig kidney into a donated body isn’t much different than a regular transplant, and “post-surgery immune-suppressing drugs are standard, too.”
But there are several crucial additional steps. For one, the animal organ selected has to undergo genetic modifications, so that the human body does not reject it.
A report from the Harvard Medical School, whose physicians were involved in Slayman’s operation, said 69 genomic edits were made to the pig kidney in his case. The gene editing technology CRISPR-Cas9 was employed to “Remove certain pig genes that produce sugars with antibodies our immune systems react to” and “Add certain human genes to improve the kidney’s compatibility with humans.”
Even after the operation, constant monitoring needs to be done to check the body’s response to the organ.
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Why are pigs often used for xenotransplantation?
Pig heart valves have been used for replacing damaged valves in humans for over 50 years now. The pig’s anatomical and physiological parameters are similar to that of humans, and the breeding of pigs in farms is widespread and cost-effective.
Also, many varieties of pig breeds are farmed, which provides an opportunity for the size of the harvested organs to be matched with the specific needs of the human recipient.
In January 2022, the first xenotransplantation of a genetically-modified pig heart was done. However, the patient passed away after two months due to a range of factors, including being tainted with a latent virus in the pig heart, which may have contributed to the dysfunction of the transplant.
What are the complications in xenotransplantation?
First, it has to be ensured that the body does not reject the organ. According to the NYU Langone website, one method of doing this is embedding the pig’s thymus gland, responsible for “educating” the immune system, underneath the outer layer of the kidney. This helps keep away any new or delayed immune responses.
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The FDA also notes concerns of potential infection of recipients with both “recognised and unrecognised infectious agents and the possible subsequent transmission to their close contacts and into the general human population.”
Another public health concern is the possibility of cross-species infection by retroviruses, “which may be latent and lead to disease years after infection.”
