The gene-edited pig heart given to a dying patient was infected with a pig virus

Revivicor, a subsidiary of United Therapeutics, developed a version of the pig that was used in Maryland.

Three US transplant teams launched the first human studies in late 2021. The University of Maryland sewed a pig heart into Bennett's chest in early January, after surgeons at New York University and the University of Alabama attached pig kidneys to brain-dead people.

Transferring pig viruses to humans has been a concern because of the fear that the viruses could spread to doctors and nurses. It could be serious enough to require lifelong monitoring for patients.

Jay Fishman, a specialist in transplant at Massachusetts General Hospital, says that the specific type of virus infections found in Bennett's donor heart is not capable of infecting human cells. Fishman thinks there is no real risk to humans.

The problem is that pig cytomegalovirus is linked to reactions that can damage the organ and the patient with catastrophic results. Two years ago, German researchers reported that pig hearts could only last a couple of weeks if the virus was present, while organs free from the infection could survive more than half a year.

The researchers said they found high levels of the virus in pig hearts. The immune systems of the baboons were suppressed with drugs, which may have caused the virus to go awry. They warned at the time that the same may happen in humans.

The pig heart recipient is with his transplant doctor.

The solution to the problem is more accurate testing according to the leader of that study. The pig's snout appears to have been tested for the virus by the US team, but often it is hidden deeper in the tissues.

If you test the animal better, it will not happen. The virus can be easily removed from pig populations, but unfortunately they didn't use a good test and didn't detect it. The pig that received the transplant was sick.

The first human-to-human heart transplant in 1967, which lasted only 18 days, and the second in Germany two years later, which lasted 27 hours, are both examples of the experiment being a great success.

Bennett's death can't be blamed on the virus alone, says Denner. It was not the sole reason, he says.

Cause of death?

Bennett's cause of death matters because if his heart failed as a result of immune rejection, researchers might need to return to the drawing board. Clinical trials of pig organs are expected to be launched within a year or two.

Bennett was offered a pig heart after the FDA granted special permission to try an animal organ in a transplant. He was considered a good candidate for the daring attempt because he was nearing death from heart failure and was ineligible for a scarce human heart for transplant due to a history of ignoring medical advice.