A pig kidney transplanted into a US man has functioned for a record 271 days, according to doctors at Mass General Brigham hospital. The patient, Tim Andrews, received the genetically modified pig organ on January 25, 2025, in a procedure aimed at addressing the critical shortage of human donor kidneys.

This extended functionality marks a significant milestone in xenotransplantation, the use of organs from different species for transplantation. Doctors hope such procedures could serve as a temporary solution, providing a bridge for patients awaiting human organs. In the United States, approximately 100,000 individuals are on the waiting list for a kidney transplant, with only about 25,000 transplants performed annually.

Andrews, who was diagnosed with end-stage kidney disease due to type 2 diabetes, expressed that the transplant offered him "hope" and a chance to escape the debilitating routine of dialysis. He described the prospect of a pig transplant as "the light at the end of the tunnel," emphasizing the desire to live a life free from the dialysis machine.

While the pig kidney eventually failed and was removed, requiring Andrews to undergo a brief period of dialysis before receiving a human donor kidney, the 271-day success demonstrates the potential of xenotransplantation. The breakthrough was detailed in the Lancet medical journal, highlighting the progress in making animal organs more compatible with the human body.

Pigs are considered ideal candidates for xenotransplantation due to their organ size and established farming practices. However, direct transplantation is complicated by the human immune system's immediate rejection of foreign organs. To overcome this, researchers have developed Yucatan miniature pigs with 69 genomic modifications.

These modifications include removing pig cell features that trigger immune responses, incorporating human DNA for camouflage, and disabling latent viruses within the pig's DNA. These complex genetic alterations are crucial for enhancing the compatibility of pig organs with human recipients.

Andrews, 66 years old at the time of the xenotransplant, experienced immediate function from the pig kidney. The procedure involved surgically connecting the pig kidney to the patient's blood vessels, enabling it to filter his blood. The images released show the patient with his medical team and his wife, Karen, celebrating his release from the hospital.

The long-term success of this pig kidney provides valuable data for ongoing research into xenotransplantation. While challenges remain, including overcoming immune rejection and ensuring long-term organ viability, this record-setting period offers a glimpse into a potential future where animal organs could significantly alleviate the global organ transplant crisis.