Xenotransplantation

Context:

Recently, A patient whose failing heart had been replaced with the heart of a genetically altered pig in a landmark surgery at the University of Maryland Medical Centre in Baltimore, United States, died, two months after the operation.

Relevance:

GS III- Science and Technology, GS II- Health

Dimensions of the Article:

1. What is xenotransplantation?
2. Why the heart of a pig?

What is xenotransplantation?

• According to the FDA, xenotransplantation is “any procedure that involves the transplantation, implantation or infusion into a human recipient of either
  • live cells, tissues, or organs from a nonhuman animal source, or
  • 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.
  • A well known case was that of an American baby, Stephanie Fae Beauclair, better known as Baby Fae, who was born with a congenital heart defect, and who received a baboon heart in 1984.
  • The surgery was successful, but Baby Fae died within a month of the transplant after the baboon heart was rejected by her body’s immune system.
  • Even so, Baby Fae managed to survive the xenotransplantation for much longer than in earlier experiments.

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  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.

-Source: Indian Express