Medical First: Pig Heart transplanted into Human

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There’s a huge shortage of human organs donated for transplant, driving scientists to try to figure out how to use animal organs instead. Last year, there were just over 3,800 heart transplants in the U.S., a record number, according to the United Network for Organ Sharing, which oversees the nation’s transplant system.



“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 Maryland university’s animal-to-human transplant program.



But prior attempts at such transplants — or xenotransplantation — have failed, largely because patients’ bodies rapidly rejected the animal organ. Notably, in 1984, Baby Fae, a dying infant, lived 21 days with a baboon heart.



The difference this time: The Maryland surgeons used a heart from a pig that had undergone gene-editing to remove a sugar in its cells that’s responsible for that hyper-fast organ rejection. Several biotech companies are developing pig organs for human transplant; the one used for Friday’s operation came from Revivicor, a subsidiary of United Therapeutics.



“I think you can characterize it as a watershed event,” Dr. David Klassen, UNOS’ chief medical officer, said of the Maryland transplant.



Still, Klassen cautioned that it’s only a first tentative step into exploring whether this time around, xenotransplantation might finally work.



The Food and Drug Administration, which oversees such experiments, allowed the surgery under what’s called a “compassionate use” emergency authorization, available when a patient with a life-threatening condition has no other options.



It will be crucial to share the data gathered from this transplant before extending it to more patients, said Karen Maschke, a research scholar at the Hastings Center, 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-to-human transplants without this information would not be advisable,” Maschke said.



Over the years, scientists have turned from primates to pigs, tinkering with their genes.



Just last September, researchers in New York performed an experiment suggesting these kinds of 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 takes their experiment to the next level, said Dr. Robert Montgomery, who led that work at NYU Langone Health.