David Bennett, a 57-year-old from Maryland, became the first person to successfully receive a heart transplant from a genetically modified pig. Photo courtesy University of Maryland Medical Center
Jan. 10 (UPI) -- A Maryland man became the first person to receive a successful pig-to-human heart transplant.
David Bennett, 57, is "still doing well" three days after the first-of-its-kind surgery, and will continue to be monitored to determine whether the transplant, conducted at the University of Maryland, provides lifesaving benefits, the university said in a statement.
"This was a breakthrough surgery and brings us one step closer to solving the organ shortage crisis. There are simply not enough donor hearts available to meet the long list of potential recipients," said Dr. Bartley Griffith, the doctor who performed the surgery.
"We are proceeding cautiously, but we are also optimistic that this first-in-the-world surgery will provide an important new option for patients in the future."
The surgery took nine hours and saw doctors replace Bennett's heart with one from a 1-year-old, 240-pound pig that was bred and had its genes edited specifically to provide organs to humans.
The pig had 10 genetic modifications that includes inactivating, or knocking out, four genes, including one that encodes a molecule that causes an aggressive human rejection response and a growth gene to prevent the pig's heart from continuing to grow after it was implanted.
Additionally, six human genes were inserted into the genome of the donor pigs to make the porcine organs more tolerable to the human immune system.
The transplant provided the first demonstration that a genetically modified animal heart can function like a human heart without being immediately rejected by the human body.
"It creates the pulse, it creates the pressure, it is his heart," Griffith told The New York Times. "It's working and it looks normal. We are thrilled, but we don't know what tomorrow will bring us. This has never been done before."
Bennett chose to undergo the experimental treatment, as he would have died without a new heart, had exhausted other methods of treatment and was not healthy enough to qualify for a heart from a human donor.
"It was either die or do this transplant," Bennett said, a day before the surgery. "I want to live. I know it's a shot in the dark, but it's my last choice."
The Food and Drug Administration granted emergency use authorization for the surgery on New Year's Eve through its expanded access provision.
Griffith said the procedure required some "clever plastic surgery to make everything fit" but added that once the clamp restricting blood supply to the organ was removed that "the heart fired right up" and "the animal heart began to squeeze."
Bennett remains connected to a heart-lung bypass machine, which he may be removed from as early as Tuesday, and is being closely monitored to ensure his body does not reject the new heart and for infections, including porcine retrovirus, a pig virus that can be transmitted to humans.