A genetically modified pig kidney has survived more than two months inside a human recipient, marking a milestone that scientists say could reshape the future of organ transplantation.
In findings published in Nature, researchers report that the pig kidney functioned for 61 days in a 57-year-old brain-dead man in the United States—the longest any genetically modified pig organ has lasted in a human body. The achievement provides crucial evidence for how rejection begins, how it can be reversed, and what future xenotransplants might require to succeed in living patients.
The experiment involved not only a pig kidney but also the donor pig’s thymus, a gland that helped the recipient’s immune system recognize the organ as its own. Researchers say this thymus inclusion likely played a major role in the kidney’s extended survival. Past transplants from genetically modified pigs—hearts, livers, kidneys, even thymuses—have had limited success, often ending either in organ removal or patient death. But this case mapped the immune system’s behavior in unprecedented detail, revealing key triggers of rejection and how to counteract them.
The transplant, performed on 14 July 2023 at New York University Langone, used an organ sourced from a Revivicor pig bearing a single genetic modification: removal of the GGAT1 gene to prevent production of a rejection-inducing sugar molecule called alpha-gal. Immediately after surgery, the kidney produced urine and appeared fully functional. But after 33 days, the organ abruptly declined as antibodies launched an attack. Doctors responded by replacing the recipient’s plasma, administering steroids, and using the drug pegcetacoplan to block immune tagging of pig cells. When a different form of immune attack emerged on day 49—this time driven by inflammatory T cells—the team halted it with a powerful T-cell–destroying immunosuppressant, restoring full kidney function.
Researchers tracked how immune signals evolved throughout the process. The pig kidney began expressing high levels of rejection-related genes, including CXCL9, CXCL10, and CXCL11, which later diminished once rejection was controlled. A surge of macrophages and natural killer cells also appeared, suggesting that certain T-cell populations play a much larger role in xenotransplant rejection than previously understood. Scientists say that real-time molecular analysis like this could enable earlier detection and intervention for rejection in future recipients.
One of the study’s most striking implications is the potential simplicity of the required genetic engineering. Many experimental pig donors carry ten or more genetic alterations, but this kidney used only a single modification. If validated in additional studies involving both brain-dead donors and living patients, this could drastically streamline pig organ production, eliminating the need for complex cloning in favor of conventional breeding.
The researchers emphasize that more work is needed. A previous transplant using the same GGAT1-deleted kidney in a living individual failed within two months due to that patient’s pre-existing heart condition. Nevertheless, teams are now preparing clinical trials with United Therapeutics to further test these organs in living volunteers.
Taken together, the findings published in Nature represent the most comprehensive look yet at how a human immune system interacts with a pig organ—and the strongest evidence so far that rejection can be reversed, controlled, and perhaps one day prevented altogether.
