Explainer: Xenotransplantation - Will animal-to-human organ transplant succeed in the near future?

It is unlikely that animal-to-human transplantation will be successful in the near future, but experts say it could be so within 30-40 years.

The process of xenotransplantation dates back to the 17th century, when attempts were made to use animal blood for transfusions. In the absence of human organs, scientists started studying non-human primates like monkeys, chimpanzees, and baboons, as well as pigs.

The experiments on pigs have shown more positive results since their organs are comparable to humans.

In spite of this, animal-to-human transplants have yet to attain lasting success, since the animal organ is always at risk of rejection by the human body.

Recent xenotransplantation cases

In January, doctors in the US successfully transplanted a genetically-modified pig heart into 57-year-old David Bennett, who suffered from terminal heart disease.

In the weeks following surgery, the transplanted heart performed well without showing any signs of rejection. While recovering the patient spent time with his family and participated in physical therapy for strength building.

Unfortunately, he passed away two months later.

Was organ rejection a factor?

Bennett may or may not have died from organ rejection.

Researchers have pointed out that early, positive outcomes don't necessarily indicate long-term success in xenotransplantation procedures.

One of the biggest challenges has been overcoming the immunological barriers that cause the immune system to reject pig organs, the doctors said.

Yet several recent xenotransplants have only involved pigs.

Researchers at the University of Alabama at Birmingham in the US have successfully transplanted pig kidneys into a brain-dead human, and the transplants weren't rejected.

An American Journal of Transplantation study published in September 2021 described the transplantation of a brain-dead patient's kidneys from a gene-edited pig. A similar surgery was performed at NYU Langone Health, New York, in October.

How come only pig organs were used in the process?

Pigs have been the focus of research for more than two decades because of physiological similarities to humans, large litter sizes of 10 or more, short gestation periods of less than four months, and lower risks of transmission of infection than non-human primates.

Can doctors force the human body to accept animal organs?

It will definitely not be easy for long-term success to overcome the rejection process.

According to some experts, Xenotransplantation could be successful because animal organs can be made more compatible with the human body.

The near future looks bright for xenotransplantation. Doctors might be able to modify the immune system or rather balance the immune system so that the body accepts these organs as parts and doesn't reject them.

It is a rapidly expanding field. At the genetic level, we have come up with a method of containing or covering those cells that can lead to the rejection of these organs. In addition, as cell technology develops, scientists can modify the DNA that becomes a part of our body. This should lead to much more successful treatments in the near future.

Ethical dilemmas

Many ethical concerns have also been raised about the use of animal organs for humans.

PETA India's science policy advisor, Dr Ankita Pandey, says more awareness is needed to solve the organ shortage, not more animals.

"Animal-to-human transplants are nothing more than vanity projects that seek to grab sensational headlines, and they are fraught with danger," she added.

(With inputs from agencies)