Surgeons in the United States have implanted the heart of a genetically modified pig into a human patient in a global first, the University of Maryland Medical School announced this week.

Although the long-term prognosis for 57-year-old patient David Bennett is uncertain, the doctors hailed it as a “historic” milestone.

Bennett, a handyman who was ineligible for a conventional heart transplant, said before the surgery: “It was either die or do this transplant. I want to live. I know it’s a shot in the dark, but it’s my last choice.”

“I look forward to getting out of bed after I recover,” he said, having been bedridden for months and hooked up to a heart-lung bypass machine. 

The US Food and Drug Administration issued a “compassionate use” emergency authorization.

“This was a breakthrough surgery and brings us one step closer to solving the organ shortage crisis,” said Bartley Griffith, one of the surgeons on the team. “There are simply not enough donor human hearts available to meet the long list of potential recipients.” 

The surgery was made possible by advances in genetic editing. Three genes—responsible for rapid antibody-mediated rejection of pig organs by humans—were “knocked out” in the donor pig. Six human genes responsible for immune acceptance of the pig heart were inserted into the genome. Lastly, one additional gene in the pig was knocked out to prevent excessive growth of the pig heart tissue, which totalled 10 unique gene edits made in the donor pig.

The animal rights group PETA responded to the news with anger.

Animal-to-human transplants are unethical, dangerous, and a tremendous waste of resources that could be used to fund research that might actually help humans. The risk of transmitting unknown viruses along with the animal organ are real and, in the time of a pandemic, should be enough to end these studies forever. Animals aren’t toolsheds to be raided but complex, intelligent beings. It would be better for them and healthier for humans to leave them alone and seek cures using modern science.

There is another curious ethical twist to the transplant, which was generally greeted as a good-news story. It turns out that Mr Bennett had been jailed for repeatedly stabbing a young man, Edward Shumaker, in 1988, leaving him a paraplegic with numerous medical conditions. He eventually suffered a stroke which left him cognitively impaired.

“The transplant gave him life,” Shumaker’s sister said of Bennett. “But my brother never got a second chance at life. Ed struggled every day for 19 years. No one deserves what he went through.”

However, the University of Maryland said that a criminal background did not disqualify Mr Bennett from receiving a life-saving transplant.

“It is the solemn obligation of any hospital or health care organization to provide lifesaving care to every patient who comes through their doors based on their medical needs,” officials said.

“Any other standard of care would set a dangerous precedent and would violate the ethical and moral values that underpin the obligation physicians and caregivers have to all patients in their care.”