Genetically Modified Pig Kidney Keeps Man Off Dialysis for 271 Days

A 66-year-old man managed to live 271 days without needing dialysis thanks to a genetically modified pig kidney, in a case that could mark a new chapter for xenotransplantation and offer a temporary alternative to patients awaiting a compatible human organ.

The case of Tim Andrews, from New Hampshire (United States), was documented by researchers at Brigham and Women's Mass General Hospital and published in the scientific journal The Lancet. According to Harvard Medical School, this is the first documented case in which a patient received a pig kidney as a temporary solution and subsequently received a human kidney.

Andrews suffered from end-stage renal disease caused by type 2 diabetes and depended on dialysis to stay alive. The chances of him receiving a human kidney within the next five years were very slim, while the risk of dying or being removed from the waiting list was considerably higher.

A pig kidney as a bridge to a human transplant

With no alternatives, doctors turned to an experimental procedure. In January 2025, Andrews received a kidney from a genetically modified miniature pig from Yucatán.

These modifications aimed to reduce the risk of the patient's immune system rejecting the organ and to decrease other risks associated with transplanting animal organs into humans.

The organ began functioning and allowed Andrews to stop undergoing dialysis for 271 days, the longest recorded period of dialysis-free survival after a xenotransplant in a living person.

During the initial stages, a rejection episode occurred, which was successfully managed with treatment. Furthermore, doctors detected no transmission of viruses or other pathogens from the pig.

The kidney eventually failed

Although the outcome was extraordinary, the porcine kidney did not function permanently.

Approximately six months after the procedure, lesions began to appear in the organ's blood vessels, which subsequently progressed to failure. The kidney had to be removed, and Andrews again relied on dialysis for several months.

One of the findings that particularly caught the researchers' attention was the absence of antibodies against the porcine kidney, suggesting that the observed rejection mechanism might differ from that typically seen in conventional transplants.

Finally, the patient had the opportunity to receive a human kidney from a deceased donor.

The human transplant functioned successfully

After receiving the human organ, Andrews recovered well. During the six-month follow-up, the new kidney functioned properly, and researchers found no evidence that the previous porcine organ transplant had impaired the human kidney's function.

This case thus represents a possible new approach: temporarily using genetically modified animal organs to keep certain patients off dialysis while they await a human organ.

A promising, but still experimental, advance

Researchers caution that this result should not be interpreted as proof that pig kidneys can already permanently replace human organs.

It involves only one patient, there is no comparison group, and the procedure required careful patient selection and highly specialized medical follow-up.

Even so, the result demonstrates the potential of xenotransplantation to address one of the biggest problems in transplantation: the shortage of available human organs.