The second person to receive a heart transplanted from a pig has died, nearly six weeks after the highly experimental surgery.
Lawrence Faucette, 58, was dying from heart failure and ineligible for a traditional heart transplant when he received the genetically modified pig heart on 20 September.
The heart had seemed healthy for the first month, according to the University of Maryland School of Medicine, but started to show signs of rejection in recent days.
Mr Faucette’s wife, Ann, said her husband “knew his time with us was short and this was his last chance to do for others”.
“He never imagined he would survive as long as he did,” she added in a statement released by the hospital.
The world’s first pig heart transplant was carried out by the Maryland team in Baltimore last year.
David Bennett survived two months before that heart failed. Why it failed was not completely clear, but signs of a pig virus were found later inside the organ.
The transplant team made changes, including better virus testing, before the second experiment.
“Mr Faucette’s last wish was for us to make the most of what we have learned from our experience,” Dr Bartley Griffith, the surgeon who led the transplant, said in a statement.
The team will analyse what happened with the heart as they continue studying pig organs, cardiac xenotransplant chief Dr Muhammad Mohiuddin added.
Attempts at animal-to-human organ transplants – called xenotransplants – have failed for decades, as people’s immune systems immediately destroyed the tissue that was not human.
Scientists are now trying to genetically modify pigs to make their organs more like those from humans.
Many scientists hope xenotransplants could one day compensate for the huge shortage of human organ donations.
There are about 7,000 people on the UK’s organ transplant waiting list.