First gene-edited pig kidney transplanted into a living person

The organ shortage has been a chronic crisis in transplant medicine for decades. At any given moment roughly 100,000 Americans are on the kidney waiting list, and thousands die each year before a donor becomes available. Xenotransplantation, using animal organs in humans, had been attempted sporadically since the 1960s, with universally poor outcomes driven by hyperacute rejection. The development of precise genomic editing tools changed the calculus, allowing researchers to knock out the pig genes most responsible for triggering human immune responses and to insert human transgenes that promote compatibility.

On March 16, 2024, surgeons at Massachusetts General Hospital transplanted a kidney from a genetically modified pig into Richard Slayman, a 62-year-old man with end-stage renal disease. His previous human kidney transplant had been failing, and he was not a straightforward candidate for a repeat human organ. The pig organ had undergone 69 genomic edits, performed by the company eGenesis: pig genes encoding antigens that provoke human rejection were knocked out, human genes involved in immune regulation and coagulation were inserted, and endogenous retroviral sequences were inactivated to reduce infection risk. Tatsuo Kawai performed the operation; Leonardo Riella, medical director for kidney transplantation at MGH, oversaw post-transplant management.

Slayman was discharged in early April 2024, about two and a half weeks after surgery, with the kidney functioning. He died on May 11, 2024; MGH stated publicly that his death appeared unrelated to the transplant. The cause was not detailed in the hospital's public statements, and MGH did not attribute the death to xenograft failure or rejection.

The procedure built directly on earlier work at NYU Langone, where a genetically modified pig kidney had been attached to a brain-dead recipient in 2021 and monitored for 54 hours, and on a second NYU case in 2023 involving a pig kidney in a brain-dead patient observed for longer. Those experiments confirmed basic hemodynamic function and short-term rejection resistance in a controlled setting, but they could not assess the immune dynamics of a living patient mounting a full physiological response over weeks and months.

The MGH case moved xenotransplantation from the carefully controlled environment of a brain-dead subject into real clinical physiology, including normal immune reconstitution, patient activity, and standard post-transplant drug regimens. Whether gene-edited pig kidneys can function for years in living recipients, and how rejection and infection risks accumulate over time, remained open questions at the time of publication.