Richard “Rick” Slayman, the first person to receive a kidney from a genetically modified pig, has died almost two months after the transplant. He was 62.
The historic procedure was carried out on March 16 at Massachusetts General Hospital. In a statement released on May 11, the hospital said it had “no indication” that Slayman’s death was the result of the pig kidney transplant.
Slayman had previously received a kidney from a human donor in 2018, but it began to fail in 2023. He was a candidate for another human kidney transplant, but because of a shortage of available organs, he would have likely waited years to receive one. Kidneys are the most needed of all donor organs, with nearly 90,000 people in the US alone waiting to receive one. For decades, researchers have been interested in the idea of using animal organs to address this problem.
Slayman’s doctors suggested a pig kidney transplant after months of dialysis complications. In dialysis, a machine connects to a major blood vessel to remove waste and excess fluid when the kidneys have stopped functioning. But Slayman’s blood vessels kept clotting and failing, landing him in the hospital regularly and significantly impacting his quality of life.
Pig kidney transplants had been tested only in recently deceased individuals up until then. Slayman was the first living person to receive one. “I saw it not only as a way to help me, but a way to provide hope for the thousands of people who need a transplant to survive,” Slayman said in a hospital statement in March.
In a press conference on March 21, Slayman’s surgical team reported that the kidney had started working normally shortly after it was in place. About a week after the transplant, however, doctors noticed initial signs of rejection. They were able to treat Slayman quickly with drugs to counteract this, and afterward he was doing so well that he was released from the hospital. No further details are known about Slayman’s condition after his discharge. When contacted by WIRED, a spokesperson for Massachusetts General said the hospital could not provide any other information at this time.
A second living person, 54-year-old Lisa Pisano, received a genetically engineered pig kidney last month. That surgery, which also included transplanting the pig’s thymus gland, was carried out at NYU Langone Health.
Transplanting organs from one species to another is known as xenotransplantation. The primary hurdle with using pig organs in people is the human immune system, which recognizes animal tissue as foreign and rejects it.
To address this incompatibility, scientists have turned to genetic engineering. In Slayman’s case, surgeons used a pig with 69 genetic edits, created by eGenesis, a biotech company in Cambridge, Massachusetts. The edits removed harmful pig genes and added certain human ones.
In the New York case, Pisano received a kidney from a pig with a single genetic edit, produced by Revivicor in Virginia. Her doctors are instead relying on the implanting of the pig’s thymus, an organ that’s part of the immune system, to help prevent rejection. Patients that get pig transplants will also need to take immunosuppressant drugs for the rest of their lives to reduce the risk of rejection.
In 2022 and 2023, surgeons at the University of Maryland tried transplanting hearts from gene-edited pigs into two patients who were not eligible for human ones. In those cases, pigs with 10 genetic edits were used. Both individuals died around two months after their transplants.
In a statement released by Mass General, Slayman’s family said they feel comforted by the optimism he provided other patients who are waiting for a transplant. “His legacy will be one that inspires patients, researchers, and health care professionals everywhere,” they said.