A man in the US has died six weeks after receiving a pig heart transplant. Lawrence Faucette was the second patient in the world to undergo the highly experimental surgery. The 58-year-old was dying and ineligible for a traditional heart transplant when he received the genetically modified pig heart on September 20.

His heart appeared healthy for the first month, his doctors at the University of Maryland School of Medicine in Baltimore said Tuesday. Faucette underwent physical therapy and worked to regain his ability to walk.

But in recent days the organ has begun to show signs of rejection. Faucette died on Monday. In a statement issued by the hospital, his wife said that her husband “knew his time with us was short and this was his last chance to do something for others. He never thought he would survive as long as he did it did.”

The Maryland team performed the world’s first transplant of a heart from a genetically modified pig to a dying man last year. 57-year-old David Bennett survived for two months. Why the organ ultimately failed is not entirely clear. Signs of a swine virus were later found inside. Lessons from that first experiment led to changes, including better virus testing, before the second attempt was made.

So-called xenotransplantations – in this case the transplanting of animal tissue and organs to humans – have failed for decades because people’s immune systems immediately destroyed the foreign tissue. Now scientists are trying again with pigs that have been genetically modified so that their organs are more similar to humans.

Dr. Muhammad Mohiuddin, the head of heart xenotransplantation, said the team will now analyze what happened to the heart while further studying the pig’s organs.

Watch the video: A moment that 42-year-old John hardly expected. Here he hears his new heart beating for the first time after an organ transplant.

Sources: Associated Press, University of Maryland