A medical center on Wednesday said a genetically-modified pig kidney is still functioning effectively 32 days after it was transplanted into a brain dead patient.

The experimental method is a component of a growing field of research aimed to advance interspecies organ donation and, as a result, shorten transplant waiting lists.

There are more than 103,000 people waiting for transplants in the United States, 88,000 of whom need kidneys.

Both of the patient’s own kidneys were removed, then one pig kidney was transplanted, and started immediately producing urine.

The experiment marks, by far, the longest time an animal’s organ has been functional inside a person albeit one who is clinically dead. One gene in the pig was deleted to prevent th

Surgeon Robert Montgomery, director of the NYU Langone Transplant Institute said, “This work demonstrates a pig kidney -— with only one genetic modification and without experimental medications or devices — can replace the function of a human kidney for at least 32 days without being rejected.”

“We’ve now gathered more evidence to show that, at least in kidneys, just eliminating the gene that triggers a hyperacute rejection may be enough along with clinically approved immunosuppressive drugs to successfully manage the transplant in a human for optimal performance—potentially in the long-term,” Dr. Montgomery said.