Human receives modified pig heart in medical first
Organ altered to prevent rejection in step that could help donor shortage
In a medical first, US doctors transplanted a pig heart into a patient in a last-ditch effort to save his life, and a Maryland hospital said that he was doing well three days after the highly experimental surgery.
While it is too soon to know if the operation really will work, it marks a step in the decades-long quest to one day use animal organs for life-saving transplants.
Doctors at the University of Maryland Medical Centre said the transplant showed that a heart from a genetically modified animal could function in a human body without immediate rejection.
The patient, David Bennett, 57, knew there was no guarantee the experiment would work but he was dying, ineligible for a human heart transplant and had no other option, his son said.
“It was either die or do this transplant. I want to live. I know it’s a shot in the dark, but it’s my last choice,” Bennett said a day before the surgery, according to a statement provided by the University of Maryland School of Medicine.
There is a huge shortage of human organs donated for transplant, driving scientists to try to figure out how to use animal organs instead.
“If this works, there will be an endless supply of these organs for patients who are suffering,” said Dr Muhammad Mohiuddin, scientific director of the university’s animal-to-human transplant programme.
But previous attempts at such transplants – or xenotransplantation – have failed, largely because patients’ bodies rapidly rejected the animal organ.
This time the Maryland surgeons used a heart from a pig that had undergone gene-editing to remove a sugar in its cells that is responsible for hyper-fast organ rejection.
“I think you can characterise it as a watershed event,” Dr David Klassen, chief medical officer of the United Network for Organ Sharing, said of the transplant. Still, Klassen cautioned that it was only a first tentative step into exploring whether xenotransplantation might finally work.
The Food and Drug Administration, which oversees xenotransplantation experiments, allowed the surgery under what is called a “compassionate use” emergency authorisation, available when a patient with a life-threatening condition has no other options.
Last September, researchers in New York performed an experiment suggesting modified pigs might offer promise for animal-to-human transplants. Doctors temporarily attached a pig’s kidney to a deceased human body and watched it begin to work. The Maryland transplant took their experiment to the next level, said Dr Robert Montgomery, who led that experiment at NYU Langone Health.
It would be crucial to share the data gathered from this transplant before opening the option to more patients, said Karen Maschke, a research scholar at the Hastings Centre, who is helping develop ethics and policy recommendations for the first clinical trials under a grant from the National Institutes of Health.
“Rushing into animal-tohuman transplants without this information would not be advisable,” Maschke said.
The surgery last Friday took seven hours at the Baltimore hospital.
“He realises the magnitude of what was done and he really realises the importance of it,” David Bennett Jnr said of his father.
“He could not live, or he could last a day, or he could last a couple of days. I mean, we’re in the unknown at this point.”