Decades Of Xenotransplantation Culminate In Experimental Pig heart And kidney Procedures
November 10, 2025 — by Transplant News
USA: Thousands of patients continue to die waiting for donor organs, with kidneys in shortest supply, and researchers have spent decades seeking alternatives that could expand transplantation options. Interest in using animal organs has persisted since the 1950s, and recent years have brought a string of high-profile, closely watched experiments using genetically modified pig organs as scientists prepare formal clinical trials.
The long arc of innovation began with the first successful human kidney transplant between identical twins in 1954, which opened modern transplantation. During the 1960s, surgeons attempted primate-to-human transplants with largely unsuccessful outcomes, culminating in the widely known 1984 case of Baby Fay, who received a baboon heart and survived 20 days. Regulatory shifts followed: in 1999 the Food and Drug Administration ended experimental use of organs from nonhuman primates, prompting investigators to focus on pigs as a viable source.
Advances in gene editing accelerated activity after 2021, when researchers placed gene-edited pig organs into people declared brain-dead to evaluate rejection and function. Surgeons then performed compassionate-use procedures: in 2022 a genetically modified pig heart was transplanted into David Bennett, who survived two months; in 2023 Lawrence Faucet received a modified pig heart and lived for six weeks. Those cases provided clinical data that shaped subsequent kidney efforts.
In 2024 the attention shifted to pig kidney transplantation. Three recipients — Rick Slayman, Lisa Pasano, and Tana Looney — all had been ineligible for standard transplants; Slayman and Pasano were critically ill and died relatively soon after, while Looney, who was healthier, experienced 130 days of graft function before the kidney was removed and she returned to dialysis. In January 2025 Kim Andrews joined the cohort as a comparatively healthier recipient, and in June 2025 Bill Stewart received a pig kidney after learning of the opportunity at his dialysis clinic. Treating physicians say each case has contributed lessons as the field advances toward the first formal trials of these gene-edited organs.
