Doctors in Alabama said that they had successfully transplanted a pair of pig kidneys into the body of a brain-dead person, potentially paving the way for clinical trials of animal-to-human transplants for patients in desperate need of kidneys and other organs.

The first-of-its-kind surgery was performed in late September at the University of Alabama at Birmingham and described in a paper published Thursday in the American Journal of Transplantation. The genetically engineered kidneys weren’t immediately rejected by the recipient’s body and showed limited function for the duration of the multiday experiment, the doctors said.

The recipient of the genetically engineered organs was James Parsons, a 57-year-old carpenter and motorcycle racer from Huntsville, Ala., who was found to be brain-dead after crashing during a race, members of his family said. In the U.S., brain death is defined as the irreversible cessation of all brain function, even if heart and lung activity can be maintained with machines.

The experimental surgery, which proceeded after discussions with ethicists and after Mr. Parsons’s family consented to the experiment, is part of a decadeslong effort to ease the chronic shortage of donor organs by allowing critically ill patients to receive pig organs rather than human ones.

“We couldn’t get Jim back for a week,” said Julie O’Hara, Mr. Parsons’s former wife. “His body had to be maintained,” she added. “That was a struggle, but we knew that the benefits of what we were doing with him outweighed those concerns.”

The surgery was initiated with the hope that it would show that pig organs can function in humans, as were a pair of operations last year in which doctors at NYU Langone Health attached a pig kidney to the upper leg of a brain-dead person.

Experiments involving the transplantation of an organ from one species to another, known as xenotransplantation, more commonly have involved the placement of genetically modified pig organs into baboons and other monkeys rather than in humans.

More than 100,000 people in the U.S. are on the national waiting list for kidneys, livers, hearts and other organs, according to the United Network for Organ Sharing, the nonprofit that under contract with the federal government helps allocate organs.

Despite efforts in recent years to increase the number of available organs, including allowing the use of organs from older or sicker donors, there is still a severe shortage. More than 6,000 patients die each year while waiting to get a new organ, according to the network.

A number of xenotransplantation researchers are in talks with the Food and Drug Administration about launching clinical trials, researchers said. So far none has begun, but researchers said they were eager for that to happen.

The recipient of the genetically engineered organs was James Parsons, in navy shirt, who was found to be brain-dead after a crash in a motorcycle race. PHOTO: PARSONS FAMILY

“We are not going to learn much more from the monkey model,” said David K.C. Cooper, a xenotransplantation researcher and faculty member at Massachusetts General Hospital in Boston.

Earlier this month doctors at the University of Maryland School of Medicine in Baltimore performed the first transplantation of a genetically modified pig heart into a living human after receiving authorization from the FDA. The recipient of the heart, 57-year-old David Bennett, remains hospitalized, according to Muhammad Mohiuddin, director of the university’s cardiac xenotransplantation program.

Dr. Mohiuddin said that in authorizing the emergency surgery for Mr. Bennett, the FDA made it clear that one-off experiments to save the lives of individual patients wouldn’t be considered a substitute for formal clinical trials of xenotransplantation. The agency told the Maryland research team that they needed more data from research on baboons before starting a clinical trial, he said.

Requests to start xenotransplantation trials will be evaluated on a case-by-case basis, an FDA spokesperson said, adding that researchers should establish “early and ongoing communication” to obtain feedback on the designs of their clinical trials.

‘The goal is not to only help one person, but to help everybody.’

— Dr. Jayme Locke, lead surgeon
The Alabama team tried to mimic the same steps “soup to nuts” that they would likely follow in a clinical trial, said Jayme Locke, director of the Heersink School of Medicine’s Comprehensive Transplant Institute at the University of Alabama at Birmingham, and the lead surgeon on the team that performed the operation. “The goal is not to only help one person, but to help everybody,” she said.

The pig kidneys used in the surgery came from a 13-month-old, 350-pound male pig that was provided by Revivicor Inc. of Blacksburg, Va. The pig had undergone 10 gene edits designed to make its organs more suitable for transplantation into people. The edits, which included the deletion of three genes that might have led to rejection by the human immune system, were made in pig cells as part of a lab process resulting in an embryo that was implanted in a sow.

The pig used in the transplant had been kept in a special germ-free facility located near the hospital. The kidneys were surgically removed and then transported on ice to the UAB human-transplant center. Before the transplantation, blood samples from the pig and Mr. Parsons were mixed together to make sure his cells didn’t attack and kill the donor cells. Similar testing is routine before human-to-human transplant surgery.

After removing Mr. Parsons’s kidneys, surgeons placed the pig kidneys into his abdomen and then attached them to blood vessels and connected their ureters to Mr. Parsons’s bladder. The surgery took about four hours.

The doctors said they monitored the transplanted kidneys for about 78 hours, noting that the right kidney produced urine within the first 24 hours following surgery though the left one made only scant amounts. They said they stopped the experiment when mechanical support was no longer sufficient to maintain Mr. Parsons’s physiological processes.

Transplant surgeons not involved in the study said the experiment showed that clinical trials are feasible. But the supply of genetically modified pigs remains limited, as does the availability of germ-free animal facilities. In addition, they said, the FDA has not yet approved some immunosuppressive drugs shown to improve the survival of baboons that received genetically modified pig organs. The same drugs might help human patients given pig organs, according to the scientists.

Dr. Cooper of Massachusetts General said future xenotransplantation efforts should focus on clinical trials rather than on more experiments on brain-dead subjects.

“What we really want to know is will the pig kidneys function for a year,” he said, adding that the only way to get the necessary information is to transplant the kidneys into living patients.

Dr. Locke said she hoped the data from the Alabama experiment would persuade the FDA to allow such a trial to proceed. Given the dire shortage of donor organs, she said, “It needs a radical solution.”

Write to Amy Dockser Marcus at [email protected]