Doctors performing surgery

A Heart Transplant from Pig to Human?

Organ transplants usually take place between patients who are best matched in terms of blood type and tissue type. A heart transplant means the donor’s heart must be the correct size to fit inside the recipient’s ribcage. On 7 January, the first heart transplant from pig to human took place. The recipient was 57-year-old David Bennet, who had terminal heart disease – the most severe form of heart failure. The transplant was the patient’s only hope. The surgery was performed at the University of Maryland Medical Centre, and Bennet is still being monitored there. This was the first time a non-human to human heart transplant took place.

What is xenotransplantation?

According to the FDA (Food and Drug Administration), xenotransplantation is a ‘procedure that involves the transplantation, implantation or infusion into a human recipient’. Primates were considered to be the most suitable for xenotransplantation due to genetic similarity, but risk of infection stopped the testing. The physiology and size of a pig is similar to that of a human. As a result, pigs have become the most suitable candidate for xenotransplantation.

Why did we decide to carry out the surgery?

The urgency of the patient’s case meant that the surgery was approved by the FDA under expanded access / compassionate use provision. This is when a medical product currently undergoing clinical testing is the only option for treating a terminal illness.

Rejection is when the immune system identifies the new organ as foreign, destroying the transplant itself. To reduce this risk, the genes of the pig heart itself were edited. This is an attempt to ‘disguise’ the organ.

In total, ten genes were altered. Six human genes were inserted into the genome (gene sequence) to increase the acceptance rate of the heart. One more gene was removed from the pig heart in order to prevent the enlargement of the heart.

What does this mean for the future?

Due to the surgery not being part of a clinical trial, researchers haven’t reached a conclusion yet. The patient will continue to be monitored to ensure the success of the xenotransplant wasn’t a fluke. Although there is still much uncertainty about the topic, the surgery will take a place in history, and companies such as eGenesis are willing to carry on research. At present, more people die waiting for organ transplants as there are a lack of donors. This type of surgery brings us hope that one day there will be universal access to organs for organ transplants.

Kamya, LV