The first person to have his failing heart replaced with that of a genetically altered pig in a groundbreaking operation died Tuesday at the University of Maryland Medical Center, two months after the transplant surgery.
David Bennett, 57, had severe heart disease, and had agreed to receive the experimental pig’s heart after he was rejected from several waiting lists to receive a human heart.
It was unclear whether his body had rejected the foreign organ.
“There was no obvious cause identified at the time of his death,” a hospital spokeswoman told New York Times.
Hospital officials said they could not comment further on the cause of death, because his physicians had yet to conduct a thorough examination. They plan to publish the results in a peer-reviewed medical journal.
Bartley Griffith, the surgeon who performed the transplant, said the hospital’s staff was “devastated” by the loss of Bennett.
“He proved to be a brave and noble patient who fought all the way to the end,” Griffith said. “Mr. Bennett became known by millions of people around the world for his courage and steadfast will to live.”
Scientists have been trying to produce pigs whose organs would not be rejected by the human body, a research effort that has picked up steam over the past decade because of new gene editing and cloning technologies.
New York surgeons announced in October that they had successfully attached a kidney grown in a genetically altered pig to a brain-dead human patient, finding that the organ worked normally and produced urine for 54 hours.
In January, surgeons at the University of Alabama at Birmingham reported that they had for the first time successfully transplanted kidneys from a genetically modified pig into the abdomen of a 57-year-old brain-dead man. The kidneys functioned and produced urine for three days.
U.A.B. surgeons said they hoped to launch a small clinical trial with live human patients by the end of the year.
The heart given to Mr. Bennett came from a genetically altered pig provided by Revivicor, a regenerative medicine company based in Blacksburg, Va.
The pig carried 10 genetic modifications. Four genes were knocked out, or inactivated, including one that encodes a molecule that causes an aggressive human rejection response.
Another gene was also inactivated to prevent the pig’s heart from continuing to grow after it was implanted. In addition, six human genes were inserted into the genome of the donor pig — modifications designed to make the pig’s organs more tolerable to the human immune system.
The transplanted heart performed well initially, and there were no signs of rejection for several weeks. Mr. Bennett spent time with his family, did physical therapy and watched the Super Bowl, hospital officials said.