Patient Who Received a Genetically Modified Pig Heart Dies After Two Months

The procedure marks the first time that a genetically-modified, non-human cardiac organ functioned without immediate rejection by the human body

Bennett with his son in the hospital
David Bennett Sr. with his son University of Maryland School of Medicine

A 57-year-old man who was the first to receive a pig heart transplant died two months after the procedure, per the University of Maryland School of Medicine. David Bennett Sr. received the organ on January 7 as a last-ditch effort to save his life after suffering from severe heart disease. 

“We are devastated by the loss of Mr. Bennett. He proved to be a brave and noble patient who fought all the way to the end. We extend our sincerest condolences to his family,” says Dr. Bartley P. Griffith at the University of Maryland Medical Center, who transplanted the heart into Bennett, in a statement. “Mr. Bennett became known by millions of people around the world for his courage and steadfast will to live.” 

Bennett arrived at the hospital last October and was deemed ineligible for a conventional heart transplant, per the university. On New Year’s Eve, the Food and Drug Administration granted emergency authorization for the never-done-before surgery. The procedure was the first time that a genetically-modified animal heart functioned like a human heart without immediate rejection by the body, according to the university. 

“Until day 45 or 50, he was doing very well, but off and on, he was having infectious episodes,” Dr. Muhammad M. Mohiuddin, director of the university's Cardiac Xenotransplantation Program, says in a video statement.  “We were having difficulty finding a balance between his immunosuppression and controlling his infection. Unfortunately, multiple organs started to fail, and finally, I think that resulted in his passing away.” 

The hospital has yet to release an official cause of death because physicians are still conducting a thorough examination, writes the New York Times’ Roni Caryn Rabin. But Bennett’s condition had been deteriorating several days prior to his death, per the hospital. In the two months following the procedure, Bennett was able to spend time with family and watch the Super Bowl with his physical therapist.

Bennett and his family
Bennett and his family University of Maryland School of Medicine

“We hope this story can be the beginning of hope and not the end,” says Bennett’s son, David Bennett, Jr., in the university statement. “We also hope that what was learned from his surgery will benefit future patients and hopefully one day, end the organ shortage that costs so many lives each year.”

Currently, more than 106,000 people are on the national transplant waiting list, with 17 people dying every day waiting for an organ. Every nine minutes, another person is added to the list.

This organ shortage has caused doctors to turn to xenotransplantation—or transplanting an animal organ into a human body. Earlier this year, doctors at the University of Alabama at Birmingham transplanted genetically altered kidneys into a brain-dead patient. The kidneys worked and produced urine for three days, per the Times

Medical professionals hold up a heart
Members of the surgical team perform the xenotransplantation at the University of Maryland Medical Center.  University of Maryland School of Medicine

To increase the likelihood of Bennett’s body accepting the heart, the donor pig had four genes knocked out—three genes responsible for rejection of pig organs by humans, and one to prevent the growth of the pig heart tissue. Six human genes were added into the genome to make the heart more welcoming to Bennett’s immune system. 

“We have gained invaluable insights learning that the genetically modified pig heart can function well within the human body while the immune system is adequately suppressed,” says Dr. Mohiuddin in a statement. “We remain optimistic and plan on continuing our work in future clinical trials.”

Though Bennett passed away, doctors say this procedure was a leap forward for xenotransplantation because he passed the one month mark, a critical milestone for transplant patients, per the Times

“This was a first step into uncharted territory,” Dr. Robert Montgomery of NYU Langone tells the Associated Press Lauran Neergaard and Carla K. Johnson. “It was an incredible feat that he was kept alive for two months and was able to enjoy his family.”