First pig-heart patient may have been killed by virus in organ

Death of man eight weeks after transplant is ‘red flag’ for surgeons if linked to animal-to-human infection

THE first person to receive a pig heart transplant may have died from complications from a pig virus, in what experts have called a “big red flag” for the future of animal-to-human transplants.

David Bennett was given the heart by doctors at the University of Maryland medical centre, in Baltimore, in January, in a medical first that offered hope to patients with failing organs.

Mr Bennett, a 57-year-old handyman who had heart failure, died eight weeks after the highly experimental surgery.

In a statement from the university in March, a spokesman said there was “no obvious cause identified” at the time of death and a full report was pending.

But Dr Bartley Griffith, Mr Bennett’s transplant surgeon, recently said the pig’s heart was infected with a porcine virus known as cytomegalovirus, which may have contributed to his death.

“We are beginning to learn why he passed on,” Dr Griffith told a conference of the American Society of Transplantation, adding that the virus “could be the actor that set this whole thing off ”. He said there was no evidence the patient’s body had rejected the heart.

Mr Bennett had been very ill before the surgery and had numerous other complications after the transplant.

“If this was an infection, we can likely prevent it in the future,” Dr Griffith said.

The heart swap was a major test of xenotransplantation, the process of moving tissues between species. But because the special pigs are meant to be virus-free, it seems the experiment was compromised by an “unforced error”.

The version used in Maryland came from a pig with 10 gene modifications developed by the biotechnology company Revivicor, which declined to comment and has made no public statement about the virus.

Mike Curtis, chief executive of egenesis, a company that also breeds pigs for transplant organs, told MIT Technology Review: “It was surprising. That pig is supposed to be clean of all pig pathogens, and this is a significant one.

“Without the virus, would Mr Bennett have lived? We don’t know, but the infection didn’t help. It likely contributed to the failure.”

Arthur Caplan, a bioethicist at New York University, described it as “a big red flag”. He said if doctors cannot prevent or control infection, then “such experiments are tough to justify”.

Scientists have long tried to develop techniques using animal organs. Previous attempts failed as patients’ bodies rapidly rejected the animal organs.

Pigs are ideal donors because of their size, rapid growth and large litters, and because they are already raised for food. In the recent attempt, doctors used a pig heart from an animal that had undergone gene-editing, whereby a particular sugar from cells was removed that previously triggered a rejection of transplanted organs.

Dr Griffith said: “This doesn’t really scare us about the future of the field ... it is just a learning point. Knowing it was there, we’ll probably be able to avoid it in future.”