Why in the news?

• In a landmark surgery  in the United States , doctors replaced the heart of a 57-year-old patient with the heart of a genetically altered pig.

Cross-species transplant(or)Xenotransplantation

• 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”.

• Xenotransplantation is seen as an alternative to the clinical transplantation of human organs whose demand around the world exceeds supply by a long distance.
• Xenotransplantation involving the heart was first tried in humans in the 1980s.

Why the heart of a pig?

• Pig heart valves have been used for replacing damaged valves in humans for over 50 years now.
• There are several advantages to using the domesticated or farmed pig (Sus scrofa domestica) as the donor animal for xenotransplantation.
• 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.

Genetically engineered pig

• The molecular incompatibility between pigs and humans can trigger several immune complications after the transplant, which might lead to rejection of the xenograft.
• To preempt that situation, genetic engineering is used to tweak the genome of the pig so as to ‘disguise’ it, so that the immune system of the human recipient fails to recognise it, and the reactions that lead to xenograft rejection are not triggered.

Reference:

1. https://indianexpress.com/article/explained/everyday-explainers/what-is-xenotransplantation-7814612/