The first person to receive a transplanted heart from a genetically modified pig is doing well after the procedure last week in Baltimore, Maryland. Transplant surgeons hope the advance will enable them to give more people animal organs, but many ethical and technical hurdles remain.
“It’s been a long road to get to this point, and it’s very exciting we are at a point where a group was ready to try this,” says Megan Sykes, a surgeon and immunologist at Columbia University in New York City. “I think there’s going to be a lot of interesting things to be learned.”
Physicians and scientists worldwide have for decades been pursuing the goal of transplanting animal organs into people, known as xenotransplantation.
Last week’s procedure marks the first time that a pig organ has been transplanted into a human who has a chance to survive and recover. In 2021, surgeons at New York University Langone Health transplanted kidneys from the same line of genetically modified pigs into two legally dead people with no discernible brain function. The organs were not rejected, and functioned normally while the deceased recipients were sustained on ventilators.
Aside from that, most research has so far taken place in non-human primates. But researchers hope that the 7 January operation will further kick-start clinical xenotransplantation and help to push it through myriad ethical and regulatory issues.
“From 4 patients, we’d learn a lot that we wouldn’t learn from 40 monkeys,” says David Cooper, a transplant surgeon at Massachusetts General Hospital in Boston. “It’s time we move into the clinic and see how these hearts and kidneys do in patients.”
Xenotransplantation has seen significant advances in recent years with the advent of CRISPR–Cas9 genome editing, which made it easier to create pig organs that are less likely to be attacked by human immune systems. The latest transplant, performed at the University of Maryland Medical Center (UMMC), used organs from pigs with ten genetic modifications.
The researchers had applied to the US Food and Drug Administration (FDA) to do a clinical trial of the pig hearts in people, but were turned down. According to Muhammad Mohiuddin, the University of Maryland surgeon who leads the research team behind the transplant, the agency was concerned about ensuring that the pigs came from a medical-grade facility and wanted the researchers to transplant the hearts into ten baboons before moving on to people.
But 57-year-old David Bennett gave Mohiuddin’s team a chance to jump straight to a human transplant. Bennett had been on cardiac support for almost two months and couldn’t receive a mechanical heart pump because of an irregular heart beat. Neither could he receive a human transplant, because he had a history of not complying with doctors’ treatment instructions. Given that he otherwise faced certain death, the researchers got permission from the FDA to give Bennett a pig heart.
