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 has announced.
The procedure took place on Friday, and while the long-term prognosis for 57-year-old patient David Bennett is uncertain, the doctors hailed it as a "historic" milestone.
Bennett, who was still in the hospital recovering on Monday, 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 added, having been bedridden for months and hooked up to a heart-lung bypass machine.
Why was it necessary to use a pig's heart?
The US Food and Drug Administration issued an emergency authorization for the procedure on New Year's Eve, a final ray of hope for a patient who was not suitable for a traditional organ transplant.
"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."
About 110,000 Americans are currently waiting for an organ transplant, and more than 6,000 patients die each year before getting one, according to official figures.
Muhammad Mohiuddin, who co-founded the university's cardiac xenotransplantation program, added the surgery was the culmination of years or research that involved transplanting pig organs into baboons.
The donor pigs are the result of gene editing that has removed certain markers that caused patients to reject the organs, or that led to the excessive growth sometimes seen in pigs.
Pig heart valves and pig skin grafts are already widely used on human patients.