A 67-year-old New Hampshire man has set a medical milestone after living more than nine months with a gene-edited pig kidney, doctors announced Monday. 

The experimental transplant, performed by surgeons at Mass General Brigham, lasted 271 days, the longest anyone has survived with an animal organ.

Doctors said Tim Andrews of Concord, New Hampshire, had the transplanted kidney removed on Oct. 23 after it began to lose function. He has since resumed dialysis while remaining on the national kidney transplant list.

Andrews is “a selfless medical pioneer and an inspiration” to patients with kidney failure, his transplant team told The Associated Press.

The case is helping scientists dive deeper into the future of xenotransplantation, or transplanting animal organs into humans, a field researchers hope could one day improve the nation’s chronic organ shortage.

Earlier efforts to use pig organs in humans, including two hearts and two kidneys, were short-lived. However, by selecting patients in better health for these trials, outcomes have improved, The Associated Press said.

An Alabama woman’s pig kidney transplant lasted 130 days earlier this year, a record that Andrews surpassed.

More than 100,000 people in the United States are currently waiting for organ transplants, most of them in need of kidneys. 

Thousands die each year before a donor match becomes available.

Andrews, whose blood type is difficult to match, volunteered for Mass General’s pilot study after learning about the experimental option. His doctors said he worked to improve his fitness before qualifying for the procedure.

In June, the Mass General team performed another pig kidney transplant in a second New Hampshire man, who continues to do well. A third and final transplant in the study is expected later this year, The Associated Press said.

Two biotechnology companies, eGenesis and United Therapeutics, are also preparing to launch larger clinical trials focused on pig kidney transplants.

Internationally, surgeons in China have reported progress in the field, including a pig kidney transplant earlier this year and a pig liver transplant that lasted 38 days before removal.