Surgeons from NYU Langone Health announced Tuesday that they had successfully transplanted two genetically modified pig hearts into brain-dead humans—moving researchers one step closer to performing xenotransplants regularly in living patients.
The two surgeries took place in June and early July.A team led by NYU Transplant Institute heart surgeon Nader Moazami undertook multi-hour surgeries to transplant the pig hearts into the chest cavities of two recently deceased patients kept alive through ventilators. The doctors monitored organ function for three days while the recipients were kept on ventilators and dialysis machines, finding that the hearts performed well without being rejected.
“It brings me great excitement to tell you that the function of the heart was excellent,” Moazami said during a press conference on Tuesday.
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Moazami said the setup for the two surgeries began in the fall of 2021. The goal was to mimic the current processes for organ transplantation while using devices, techniques, and medications that were all approved for human use, and not experimental. The team first modified 10 of the pig donors’ genes in order to reduce the risk of transplant rejection and maintain compatibility with a human chest cavity.
The operating room where the genetically modified pig heart is transplanted in a recently deceased donor at NYU Langone Health on Wednesday, July 6, 2022 in New York, NY.
Joe Carrotta for NYU Langone Health“It was one of the most incredible things to see a pig heart pounding away and beating inside of the chest of a human being,” NYU transplant surgeon Robert Montgomery told reporters.
More than 100,000 people in the U.S. are waiting for organ transplants, due to a long standing shortage of donors. Only about 3,500 heart transplants are performed annually, Alex Reyentovich, an NYU Langone cardiologist, said during the press conference.
“We have a tremendous deficiency in organs,” and many people die waiting for a heart, Reyentovich said. “Xenotransplantation really has the capability of addressing some of those supply limitations and saving innumerable lives.”
These experiments mark the second and third successful xenotransplantations of a pig heart to a human. University of Maryland Medical Center surgeons transplanted a genetically engineered pig heart to a living patient in January, but the recipient died two months later from heart failure. Specialists pointed to evidence that the tissue had carried a pig virus, which could have contributed to the patient’s death.
“In the end, we don't really know why that heart failed and he died,” Montgomery said. Even so, in the trials undertaken by NYU, the transplanted pig hearts were screened for porcine cytomegalovirus and other pathogens of concern with tests developed in-house.
An advantage of working with non-living patients, Montgomery added, was the ability to intensively monitor the transplanted organs.
“The amount that we could learn was tremendous, and extending that beyond 72 hours would give us even more information,” he said.
Montgomery said he anticipated that the Food and Drug Administration could approve a Phase I clinical trial within the next few years. That would mean that at least one living patient would undergo a xenotransplant to gauge the safety of the procedure and study its effects on the human body. But Moazami stressed that there are many questions that remain unanswered including the long-term viability of these genetically modified pig hearts, and the ideal patient population for receiving potential xenotransplants.
Still, he said the team is looking at the results with “cautious optimism.”
“We learned a tremendous amount from the first operation, and when that experience was translated into the second operation, it even performed better,” Moazami said.
