NEW YORK (NEWSnet/AP) — Surgeons transplanted a pig’s kidney into a brain-dead man and, for more than a month, it has functioned normally. It’s a critical step toward an operation the New York team hopes to try eventually  in living patients.

The experiment, announced Wednesday by NYU Langone Health, marks the longest a pig kidney has functioned in a person, albeit a deceased one. Researchers are set to track the kidney’s performance for a second month.

“Is this organ really going to work like a human organ? So far, it’s looking like it is,” Dr. Robert Montgomery, director of NYU Langone’s transplant institute, told The Associated Press.

“It looks even better than a human kidney,” Montgomery said on July 14, as he replaced a deceased man's kidneys with a single kidney from a genetically modified pig — and watched as it started to produce urine.

The possibility that pig kidneys one day might help to ease a shortage of transplantable organs persuaded the family of Maurice “Mo” Miller from upstate New York to donate his body for the experiment. He had died unexpectedly at the 57 with a previously undiagnosed brain cancer, ruling out routine organ donation.

His sister, Mary Miller-Duffy, told the AP she struggled with the decision. But her brother liked to help other people and “I think this is what (he) would want … "He’s going to be in the medical books, and he will live on forever,” she added.

Attempts at animal-to-human transplants, or xenotransplantation, have failed for decades, as people's immune systems attacked foreign tissue. Now, researchers are using pigs that are genetically modified so their organs match human bodies more closely.

In 2022, with special permission from regulators, University of Maryland surgeons transplanted a gene-edited pig heart into a dying man who had no other options. He survived two months before the organ failed.

U.S. Food and Drug Administration is considering whether to allow some small, but rigorous, studies of pig heart or kidney transplants in volunteer patients. The NYU experiment is one of a string of developments aimed at speeding the start of such clinical trials.

Also on Wednesday, University of Alabama at Birmingham announced that two pig kidneys worked normally inside a donated body for seven days.

Kidneys do more than make urine, they provide range of functions in the body. In the journal JAMA Surgery, UAB transplant surgeon Dr. Jayme Locke reported lab tests documenting the gene-modified pig organs' performance. She said the weeklong experiment demonstrates they can “provide life-sustaining kidney function.”

Previously, NYU and a team at University of Alabama at Birmingham had tested pig kidney transplants in deceased recipients for two or three days. An NYU team also had transplanted pig hearts into donated bodies for three days of intense testing.

More than 100,000 patients are on the nation’s transplant list and thousands die each year waiting.

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