Pig heart transplanted to human for the first time

The transplant team has a replacement heart.

The University of Maryland School of Medicine announced on Monday that it had completed the first transplant of a pig's heart into a human. The patient who received the heart was too sick to be considered for a transplant. The patient was alive for three days after the procedure.

The idea of using non-human organs as replacements for damaged human ones has been around for a long time. In recent years, our ability to do targeted gene editing has motivated researchers to start genetically modifying pigs in order to make them better donors. The recent surgery wasn't part of a clinical trial, so it shouldn't be viewed as an indication that this approach is ready for widespread safety and efficacy testing.

The surgery was authorized by the FDA under its compassionate use program, which allows patients with life-threatening illnesses to receive treatments that haven't gone through rigorous clinical testing yet.

The heart used for this transplant was genetically modified to reduce the chance of rejection by the human immune system. There are a number of lines that have been engineered with this in mind and there is a review of some of the competing ideas on what to modify. The Revivicor company that developed this line didn't give any details on the changes they made to the product. There is only one hit that involves a completely different pig line when searching for Revivicor.

Advertisement

It's difficult to know what genes were changed in these pigs. According to the University of Maryland press release, there were four genes knocked out of the pig to lower its immune profile and avoid rejection. Six human genes were inserted into pigs to increase the human immune system's tolerance. The potential list of targets is much larger than what has been edited.

The amount of effort that has gone into generating the pig lines made it certain that these transplants would be attempted soon. It's difficult to judge this first effort on a scientific level because of the lack of details about the commercially developed heart donor. The transplant took place without a plan for assessing the safety of the transplant, which raises questions about how informative the first effort will be.

A person who has been in the hospital for months for a lack of a properly functioning heart now has one. It will likely tell us something if it remains functional.