What’s in the news?

• The first recipient of a modified pig kidney transplant passed away recently around two months after the surgery was carried out.

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. It includes transplantation of animal organs (like a pig kidney), or use of a pig liver for temporary perfusion during acute liver failure.

Need for this procedure

• 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.

How does xenotransplantation happen?

• In practice, the actual surgery may not be very different from a regular organ transplant. But, there are several crucial additional steps. The animal organ has to undergo genetic modifications so that the human body does not reject it. 
  • The gene editing technology CRISPR-Cas9 can be 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.

• After the operation, constant monitoring needs to be done to check the body’s response to the organ.

Why are pigs often used for xenotransplantation?

• Pig’s anatomical and physiological parameters are similar to that of humans, 
• The breeding of pigs in farms is widespread and cost-effective.
• 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.

Earlier cases of Xenotransplantation

•  Pig heart valves have been used for replacing damaged valves in humans for over 50 years now.
• 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.

Complications in xenotransplantation

• It has to be ensured that the body does not reject the organ. 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.
• 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.

Source

• https://indianexpress.com/article/explained/everyday-explainers/pig-kidney-transplant-death-xenotransplantation-9325986/