A US man has become the first person in the world to get a heart transplant from a genetically-modified pig.
David Bennett, 57, is doing well three days after the experimental seven-hour procedure in Baltimore, doctors say.
The transplant was considered the last hope of saving Mr Bennett's life, though it is not yet clear what his long-term chances of survival are.
"It was either die or do this transplant," Mr Bennett explained a day before the surgery.
"I know it's a shot in the dark, but it's my last choice," he said.
Doctors at the University of Maryland Medical Center were granted a special dispensation by the US medical regulator to carry out the procedure, on the basis that Mr Bennett - who has terminal heart disease - would otherwise have
He had been deemed ineligible for a human transplant, a decision that is often taken by doctors when the patient is in very poor health.
The pig used in the transplant had been genetically modified to knock out several genes that would have led to the organ being rejected by Mr Bennett's body, the AFP news agency reports.
For the medical team who carried out the transplant, it marks the culmination of years of research and could change lives around the world.
Surgeon Bartley Griffith said the surgery would bring the world "one step closer to solving the organ shortage crisis". Currently 17 people die every day in the US waiting for a transplant, with more than 100,000 reportedly on the waiting list.