A unique feat has occurred in the history of medical science, offering renewed hope to doctors and kidney patients around the world. Doctors in the United States successfully transplanted a pig kidney into 66-year-old Tim Andrews. This pig kidney functioned successfully in the patient's body for a record 271 days.

This is the longest-lasting case of an animal organ functioning in a human body in medical history. A report detailing the entire process and its results has been published in the renowned medical journal The Lancet.

Patient Tim Andrews suffered from type 2 diabetes, which had completely damaged both of his kidneys. Doctors told him he would have to wait at least seven years to receive a human kidney. Patients on dialysis typically cannot wait that long. 

In such a difficult time, doctors at Massachusetts General Hospital advised him to undergo xenotransplantation, or transplanting an organ from an animal into a human. On January 25, 2025, doctors transplanted a pig kidney into Tim's body. After this transplant, Tim did not need to go to the hospital for several months to have his blood cleaned with a dialysis machine, and he lived a normal life.

What Is Xenotransplantation

When an animal's organ, cell, or tissue is transplanted into a human body, this entire medical procedure is scientifically known as xenotransplantation. Doctors say that pigs are considered the most suitable animal for this procedure because of their resemblance to human organs.

Why Can Only Pig Kidneys Be Transplanted?

In the first months after the transplant, Tim's body was completely healthy. Initially, when the immune system tried to reject the organ, doctors managed the situation by adjusting his medications. But after about six months, the blood vessels in the pig's kidney gradually became damaged, causing the organ to swell. In October 2025, the kidney stopped functioning, forcing doctors to surgically remove it.

Pig's Body Parts Served As A Bridge

Dr. Leonardo Riela of the Center for Transplantation Sciences at Mass General Brigham stated that the pig kidney served as a bridge for the patient. After the pig kidney was removed, Tim needed to return to dialysis for only 82 days. Shortly thereafter, in January 2026, he received a human kidney from a deceased donor. According to doctors, the human kidney is now functioning well in Tim Andrews' body.