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Doctors Transplant Genetically Modified Pig's Heart Into Human in Medical First

The milestone operation shines a hopeful light for the long ledger of patients awaiting organ transplants.

Monisha Ravisetti Former Science Writer
Monisha Ravisetti was a science writer at CNET. She covered climate change, space rockets, mathematical puzzles, dinosaur bones, black holes, supernovas, and sometimes, the drama of philosophical thought experiments. Previously, she was a science reporter with a startup publication called The Academic Times, and before that, was an immunology researcher at Weill Cornell Medical Center in New York. She graduated from New York University in 2018 with a B.A. in philosophy, physics and chemistry. When she's not at her desk, she's trying (and failing) to raise her online chess rating. Her favorite movies are Dunkirk and Marcel the Shell with Shoes On.
Monisha Ravisetti
3 min read
Watch this: How Doctors Gave a Man a Genetically Modified Pig Heart

On Jan. 7, an ambitious crew of doctors transplanted a genetically modified pig's heart into a human patient for the first time, marking a historic moment for medicine. In an update on March 9, the Maryland hospital where the procedure took place announced that the organ recipient, David Bennett Sr., had died

The surgeon who performed the transplant operation described Bennett as "a brave and noble patient" and noted that his death on Tuesday will not be in vain. The groundbreaking procedure, Dr. Bartley P. Griffith said in a statement Wednesday, has "led to valuable insights that will hopefully inform transplant surgeons to improve outcomes and potentially provide lifesaving benefits to future patients."

In early February, five weeks after the operation, the 57-year-old Bennett had been doing well in his post-surgery recovery. In an update on Feb 11, Griffith, of the University of Maryland School of Medicine, had this to report: "His heart function looks great, his blood pressure looks very good, and in fact, he's on medicine to reduce his blood pressure. That's how good it is right now."


Members of the University of Maryland School of Medicine team show the pig's heart prior to transplantation.

University of Maryland School of Medicine

On Feb. 14, medical staff caring for Bennett released an inspiring clip of him watching this year's Super Bowl and singing "America the Beautiful" as Jhené Aiko performed her rendition at the game. While the team continues to monitor Bennett closely, particularly due to reported preoperative kidney setbacks that persisted after the procedure, Griffith offered encouraging words: "Beyond that, I'd say all thumbs are up." 

This medical milestone undoubtedly lays the groundwork for a new generation of animal-to-human organ transplants, known as xenotransplantation, and directly addresses the organ shortage crisis. "There are simply not enough donor human hearts available to meet the long list of potential recipients," Griffith, who's also a professor in transplant surgery at the university, said in a statement. 

"We are also optimistic that this first-in-the-world surgery will provide an important new option for patients in the future," Griffith said. According to organdonor.gov, well over 100,000 Americans are awaiting an organ transplant, and more than 17 patients die each day while still on the waitlist. 

Leading up to his surgery, Bennett was one of those anxious patients on hold. He was hospitalized and bedridden due to terminal heart disease.

"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 was conducted, according to a statement provided by the University of Maryland School of Medicine. Several leading transplant centers had previously deemed Bennett ineligible for a conventional heart transplant, including UMSOM, where the groundbreaking surgery was performed. 

"I look forward to getting out of bed after I recover," Bennett said.

To conduct the life-saving operation as a last resort, doctors genetically modified a pig's heart to increase the chances of Bennett's body accepting it as its own circulatory control center. Without such modifications, nonhuman-to-human organ transplants carry risks like triggering severe, and sometimes fatal, immune responses. 

Further guarding against the likelihood of a bodily rejection, physicians behind the surgery's blueprint also administered certain drugs that suppress the immune system, which the UMSOM report says helped Bennett's body accommodate the foreign organ.

"This is the culmination of years of highly complicated research to hone this technique in animals, with survival times that have reached beyond nine months," Muhammad M. Mohiuddin, a professor of surgery at the University of Maryland School of Medicine who established the cardiac xenotransplantation program with Griffith, said in a Jan. 10 statement. "The FDA used our data and data on the experimental pig to authorize the transplant in an end-stage heart disease patient who had no other treatment options." 

"We've been asked how we would define success," Griffith said in the team's Feb. 11 update, underlining his cautious hope. "I think we've surpassed, in many measures, what we expected."