The procedure was the first of its kind and represents an advance in efforts to determine whether organs in non-human animals can be modified and successfully used in humans in need of transplantation.
The 72-year-old recipient, Lawrence Kelly of Pennsylvania, was pronounced brain dead. His family donated his body to the study, which was designed to examine how well the modified pig heart works in the body of a deceased human.
After Kelly’s transplant in June, the research team repeated the procedure in early July with another deceased recipient, 64-year-old Alva Capuano of New York City.
dr Robert Montgomery, director of the NYU Langone Transplant Institute, said the procedures allowed for a more thorough study of how well the recipients’ bodies tolerate the pig hearts.
“We can monitor a lot more often and really understand the biology and fill in all the unknowns,” he said.
He added that their study is unique because they tried to emulate real-world conditions, for example by not using experimental devices and drugs.
Researchers are working to release more details of the study.
“He left home a hero”
Researchers traveled abroad to source the heart, which featured genetic changes aimed at a range of factors, including modulating organ growth and reducing the likelihood that the recipient’s immune system would reject it.
The flight meant the team could replicate the conditions of a typical heart transplant, said Dr. Nader Moazami, Surgical Director of Heart Transplantation at NYU Langone Health.
“It was about an hour and 15 minutes’ flight time from New York, which is typical of the distance we take hearts for clinical transplants,” said Moazami, who performed the transplant.
The heart went out to Kelly, a Navy veteran who was pronounced brain dead after a car accident. Kelly’s fiancé, Alice Michael, approved of the donation of his body for research.
“They wanted to remove his liver and couldn’t find a recipient. And then New York University called me with this research thing. And I automatically said yes because I know he would have wanted it. He loved helping people,” she said.
“When they asked me, I didn’t have to think twice. I just automatically said yes because I knew it was groundbreaking research and I know he would have wanted it. It was hard because I had to wait to be buried. But in the long run maybe he can help a lot of people.
“He was a hero in life and he walked out a hero,” Michael said.
After the transplant, the researchers ran tests for three days to monitor how well the heart was accepting. while the recipient’s body was kept alive with machinery including ventilation.
In addition, the researchers said they found no evidence of porcine cytomegalovirus (pCMV) infection, which experts feared could pose a barrier to using pig organs in human recipients.
A new method for transplantation research
Testing how well an organ transplant works on the donated body of a deceased person is a new method, Moazami said. The first use of this technique for research came in September, when a team from NYU Langone led by Montgomery transplanted a kidney from a genetically modified pig into a deceased human.
Although the study represents a step forward, Moazami said, there is still a long way to go before such a technique is made widely available outside of a research setting.
“There’s still a long way to go from here to clinical transplantation to support a patient longer term,” he said. “There are still many, many, many questions that need to be answered.”
An important limitation is the length of the study, he said; Organ and recipient were evaluated just 72 hours after transplantation. In addition, there could be important differences in how deceased human bodies respond to the procedure compared to living humans. More research is needed to determine how transplant recipients would fare in the long term.
“We thought that in 72 hours we could learn all the things that we would learn if we extended this a bit more,” Moazami said, noting that the short time frame limited the study’s cost and it’s kind to the recipient’s body enabled him to return to his family more quickly.
“We felt 72 hours was a reasonable amount of time for our short-term study to understand all the things we needed – that three days versus five days versus seven days wouldn’t make a difference. Would three days versus a month make a difference? Yes absolutely. But at that stage it would have been very, very difficult to pull it off.”
Transplanting animal organs into humans also raises a number of other ethical questions, such as whether the benefits of using a modified pig heart outweigh the risks a patient would face if they instead waited for a human organ to become available.
Personal connection and a new frontier
For Montgomery, research has a personal side. He is a human heart transplant recipient, and he said the difficulty of obtaining a transplant is part of what motivates his work.
“During my illness, I realized that this paradigm doesn’t work. It’s a failing paradigm and that we need a renewable resource, an alternative source of organs that doesn’t require someone to die in order for someone else to live,” he said.
“My whole illness has been about educating myself about the reality of it and changing the way I think, not that it’s not important to keep doing what we’re doing, but we need to take this in a completely different direction. “
Moazami suggested that animal transplants could one day be useful in pediatrics, where patients face even greater challenges in receiving a timely human organ transplant. Animal organs could be used as a “bridge” to buy time before a more optimal human organ becomes available.
“Perhaps the best way to study this is, maybe use it as a bridge to a human transplant, if you will, so that any patient who needs an organ can have that heart, with the caveat that if a human heart becomes available and it fits the recipient, we’ll swap it out,” said Moazami.