Xenotransplantation - A Medical Breakthrough

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Last Updated19/01/2022

On January 10, the University of Maryland School of Medicine announced that it had successfully transplanted a genetically-modified pig heart into a patient with life-threatening arrhythmia, a disorder that affects the rate or rhythm of heartbeats.
The patient, David Bennett (57), was deemed ineligible for a conventional heart transplant or an artificial heart by leading transplant centers after a review of his medical records.

In January, 1964, Dr. James Hardy and his team at the University of Mississippi transplanted a chimpanzee’s heart into a 68-year-old man.
The first cardiac transplant into a human was a xenotransplant, and it failed within hours.

It is the first genetically-engineered porcine heart transplanted into a 57-year-old patient at the University of Maryland on January 7, 2022 by Dr. Bartley Griffith and his surgical team.
The patient is currently awake, breathing on his own, and successfully weaned off of mechanical circulatory support.

Xenotransplantation(heterologous transplant) is the process of the transplantation of living cells, tissues or organs from one species to another. Such cells, tissues or organs are called xenografts or xenotransplants.
Arrhythmia - Rate or rhythm of the heartbeat are too quick, too slow, or with an irregular pattern.

According to the health ministry, around 0.18 million people in India suffers kidney failures every year(only 6,000 transplants).
25,000-30,000 liver transplants are needed every year in India(only 1,500 are being performed).
50,000 - heart failure(only 10-15 heart transplants).

Kidney, liver and heart transplants from non-human primates to humans happened in the 1970s. failed due to rejection.
In 1984, a human infant received a heart from a baboon. The experiment failed when the baby died after 21 days.
In September 2021, surgeons at the New York University Langone Health medical center transplanted a kidney of a genetically modified person into a brain-dead person.
The second such pig kidney experiment was carried out in November, 2021 on a person in a ventilator(The process of genetic modification to protect from rejection).
In India as well, Dhaniram Baruah, a cardio-thoracic surgeon based in Sonapur near Guwahati, transplanted the organs of a pig into a human body in 1997(It failed).

The human immune system rejects anything foreign, scientists tweaked the pig genome is less likely to be rejected.
A small herd of genetically engineered pigs is being raised.
10 pigs - Their genes genetically modified to reduce the possibility of rejection.
4 are inactivated, 6 human genes were inserted to further reduce the risk of rejection.
In the 1990s, all human immune reactions were centered against one pig antigen i.e. a sugar molecule present on cell surfaces.
DNA of pigs also contains retroviruses that can infect human cells.
Many retroviruses have been removed from the organ to make it safer when transplanted.
Genome-editing tools such as CRISPR/Cas9, made gene modification simpler, fast and accurate.

This is an experimental surgery and brings with huge risks for the patient.
Even well-matched human donor organs can be rejected after they are transplanted and with animal organs, the danger is likely to be higher.
Chances Of Infection - High Community Risk

Use of pigs for human transplants, which many animal rights groups oppose.
People for the Ethical Treatment of Animals (PETA) has condemned the experiment as ""unethical, dangerous, and a tremendous waste of resources"".

Another dilemma emerges around the acceptance of animal organs based on their religious faiths
Rich and Poor Differentiation