Context: Recently, the University Of Maryland School Of Medicine announced that it had successfully transplanted a genetically-modified pig heart into a patient with severe ailments.
Key Points

• Pigs are increasingly becoming popular candidates for organ transplantation. This is because their organs are anatomically similar to those of humans. 
• Pigs have been contributing to medical research for several years.
• This success could potentially end the years-long backlog of people waiting to receive a healthy organ and open up a brave new world of possibilities.

What is Xenotransplantation?

• It is the process of grafting or transplanting organs or tissues between members of different species.
• It has been pursued by modern medical science for decades, but experts have found it difficult to surmount the challenge presented by the immune system’s rejection of an alien organ, ending in deadly outcomes for patients.

Process

• The transplanted heart was harvested from a pig that had undergone genetic editing that saw scientists remove three genes “that would have led to the rejection of pig organs by humans” along with one that would have led to excessive growth of pig heart tissue.
• Further, six human genes that would have facilitated the organ’s acceptance by the human body were inserted into the pig genome.

Organ Shortage Problem

• In India, patients need 25,000-30,000 liver transplants annually. But only about 1,500 end up receiving them. 
• Similarly, nearly 50,000 persons suffer from heart failures annually. Still, only about 10-15 heart transplants are performed every year
• One of the biggest obstacles to transplantation is organ rejection. Scientists have addressed the problem by genetically altering pigs’ organs.

Early xenotransplantation attempts

• A spate of kidney, liver and heart transplants from non-human primates to humans happened in the 1970s. A majority of them failed.
• This is attributed to organ rejection — our immune system rejects agents that are foreign to the body. Surgical complications were also behind the failure.
• In 1984, a human infant received a heart from a baboon. She died 21 days after the transplant.
• Primates fell out of favour in the 1990s because they were susceptible to virus spread. This brought pigs into the spotlight.

Early Attempts

• In 2017, Chinese surgeons reportedly transplanted pig cornea to restore sight in a human.
• In 2020, US experts attached a genetically-altered kidney to a brain-dead person.

Issues with Xenotransplantation
Besides scientific challenges, there are several ethical challenges to overcome:

• Animal rights: Many, including animal rights groups, strongly oppose killing animals to harvest their organs for human use.
• Decreased life expectancy: In the 1960s, many organs came from the chimpanzees, and were transferred into people that were deathly ill, and in turn, did not live much longer afterwards.
• Religious violations: Certain animals such as pork are strictly forbidden in Islam and many other religions.
• Informed consent: Autonomy and informed consent are important when considering the future uses of xenotransplantation.
• Threats of zoonosis: The safety of public health is a factor to be considered. We are already battling the biggest zoonotic disease threat.