SUMMARY

• Tim Andrews lived without dialysis for 271 days after receiving a genetically modified pig kidney.
• The kidney later failed, but he successfully received a human donor kidney.
• Researchers say the case could help advance xenotransplantation research.

A genetically modified pig kidney kept a 66-year-old man off dialysis for 271 days before he received a human donor kidney, marking a major milestone in xenotransplantation research.

Tim Andrews received the experimental pig kidney in January 2025 after developing end-stage kidney disease. He had previously relied on haemodialysis and had no living donor available.

Doctors at Massachusetts General Hospital and Mass General Brigham reported the case in a study published in The Lancet on Sept. 3, 2026.

Pig Kidney Worked For Nearly Nine Months

After the transplant, the pig kidney began functioning immediately. Andrews remained free from dialysis for 271 days, or almost nine months.

Researchers described this as the longest reported period a living human has remained dialysis-free following a pig-kidney xenotransplant.

Andrews had been facing a potentially lengthy wait for a human kidney. Researchers estimated that his expected waiting time could exceed five years, making the experimental transplant a possible temporary bridge while he waited for a suitable human organ.

The kidney came from a genetically modified pig. Scientists altered the animal’s genes to make the organ more compatible with the human body and reduce the risk of immune rejection.

Xenotransplantation refers to transplanting organs, tissues or cells between different species. Scientists have been studying genetically modified pigs as a potential source of organs becau...