Pig-Heart Transplant Offers Hope for Organ-Donor Gap

"The first transplant of a genetically modified pig heart into a human jolted doctors involved in a decadeslong effort to address the chronic shortage of organ donors.

Doctors for the critically ill patient, David Bennett, a 57-year-old handyman and father of two, had requested emergency authorization for the experimental surgery from the Food and Drug Administration because Mr. Bennett was dying and ineligible to receive a human-heart transplant.

The agency granted the request on New Year's Eve, and the surgery was performed Jan. 7 at the University of Maryland Medical Center in Baltimore, the center said.

"We have crossed the Rubicon," Robert Montgomery, director of the NYU Langone Transplant Institute, said on the first-of-its-kind surgery. "We are trying to make sense of it and where to go next." He wasn't involved in the surgery.

The Maryland center is one of several transplant centers that had declined to list Mr. Bennett for the chance to receive a human heart because he had failed to comply with doctors' orders and attend follow-up visits, said Mr. Bennett's son, David Bennett Jr.

Bartley P. Griffith, a professor of transplant surgery who performed the operation, said transplant centers follow strict guidelines when deciding who is eligible for heart transplantation.

In the case of the elder Mr. Bennett, "We couldn't offer him the treasure that is a human heart," Dr. Griffith said, adding that the availability of the pig heart opened up a potentially lifesaving opportunity.

Last year, surgeons performed more than 41,000 organ transplants in the U.S., a record, according to the United Network for Organ Sharing. More than 100,000 patients are on the waiting list for a donor organ at any given time; more than 6,000 patients die every year before getting one, a spokeswoman for the network said.

To address the shortage, researchers have been trying for decades to develop the transplantation of an organ between different species, or xenotransplantation.

Researchers reported in 2015 that they had used Crispr, a new gene-editing technology, to inactivate pig viruses that otherwise might infect humans transplanted with pig organs.

One baboon that received a transplanted genetically modified pig heart survived for nine months, said Muhammad Mohiuddin, a professor of surgery at the University of Maryland who helped establish the university's cardiac xenotransplantation program.

Revivicor, the Blacksburg, Va., company that provided the pig whose heart was given to the elder Mr. Bennett, made genetic changes to the heart to make it more compatible with the human body, including inactivation of genes that might have triggered the organ's rejection.

Many xenotransplantation researchers have spent decades pursuing experiments and trying to gather data sufficient to justify clinical trials in humans.

That is "a difficult bar to meet," Dr. Montgomery said, adding that researchers have been conducting experiments on nonhuman primates with the goal of showing that a human patient given a pig kidney could expect to live at least two years following surgery.

Many doctors in the field think that nonhuman primate studies have advanced as far as they can and that the only way to determine whether pig organs will work in humans is to transplant them, Dr. Montgomery said. In September, his team attached a genetically modified pig kidney to the upper leg of a deceased patient who was maintained on a ventilator. Over 54 hours of follow-up, Dr. Montgomery said, the kidney functioned normally.

The researchers said more studies were needed before launching clinical trials involving the transplantation of pig kidneys." [1]

1.   U.S. News: Pig-Heart Transplant Offers Hope for Organ-Donor Gap
Marcus, Amy Dockser. Wall Street Journal, Eastern edition; New York, N.Y. [New York, N.Y]. 13 Jan 2022: A.3.