Pig kidney functions for 2 months in donated body, raising hope for animal-human transplants

NEW YORK (AP) — Dozens of doctors and nurses silently lined the hospital hallway to pay tribute: For two historic months, a pig’s kidney functioned normally inside the brain-dead man on the gurney rolling past them.

The dramatic experiment ended Wednesday when surgeons at NYU Langone Health removed the pig’s kidney and returned Maurice “Mo” Miller’s donated body to his family for cremation.

It was the longest time a genetically modified pig kidney has ever functioned in a human, albeit a deceased one. And by pushing the boundaries of research with the dead, the scientists learned important lessons that they now want to share with the Food and Drug Administration in hopes of eventually testing pig kidneys on the living.

“It’s a combination of excitement and relief,” said Dr. Robert Montgomery, the transplant surgeon who led the experiment, told The Associated Press. “Two months is a long time to have a pig kidney in this good condition. That gives you a lot of confidence for the next attempts.”

Montgomery, a heart transplant recipient himself, believes animal-to-human transplants are crucial to alleviating the country’s organ shortage. More than 100,000 people are on the national waiting list, most of whom need a kidney, and thousands will die waiting.

So-called xenotransplantation attempts have been failing for decades – the human immune system destroys foreign animal tissue immediately. What’s new: Trying to genetically modify pigs to make their organs more human-like.

Surgeons remove a genetically modified transplanted pig kidney from the body of Maurice “Mo” Miller on September 13, 2023 at NYU Langone Health in New York.
Surgeons remove a genetically modified transplanted pig kidney from the body of Maurice “Mo” Miller on September 13, 2023 at NYU Langone Health in New York.

Some short experiments on deceased bodies They avoided an immediate immune attack but did not shed light on a more common form of rejection that can take a month to develop. Last year, surgeons at the University of Maryland tried to save one Dying man with pig’s heart – but he only survived two months because the organ failed for unclear reasons. And the FDA gave Montgomery’s team a list of questions about how pig organs really do their job compared to human organs.

Montgomery figured some of these questions could be answered by keeping Miller’s body on a ventilator for two months to see how the pig’s kidney worked.

“I’m so proud of you,” Miller’s sister, Mary Miller-Duffy, said in a tearful farewell at her brother’s bedside this week.

Miller had collapsed and was declared brain dead because he was unable to donate organs because of cancer. After wrestling with the choice, Miller-Duffy donated the Newburgh, New York, man’s body for the pig experiment. She recently received a card from a stranger in California awaiting a kidney transplant thanking her for helping advance much-needed research.

“It’s been quite a journey,” Miller-Duffy said as she and her wife, Sue Duffy, hugged Montgomery’s team.

On July 14, just before his 58th birthday, surgeons replaced Miller’s own kidneys with a pig kidney and the animal’s thymus, a gland that trains immune cells. The kidney was functioning for the first month without any signs of problems.

But soon after, doctors noticed a slight decrease in the amount of urine produced. A biopsy confirmed a subtle sign that rejection was beginning – and gave doctors a chance to determine whether it was treatable. In fact, the kidney’s performance recovered by changing the standard immunosuppression drugs used by patients today.

“We are learning that this is actually feasible,” said NYU transplant immunologist Massimo Mangiola.

Researchers reviewed other FDA questions and found, among other things, that there were no differences in the pig kidney’s response to human hormones, antibiotic excretion, or the occurrence of drug-related side effects.

“It looks beautiful, it’s exactly what normal kidneys look like,” said Dr. Jeffrey Stern on Wednesday after removing the pig’s kidney for closer examination after 61 days.

What’s next: Researchers collected about 180 different tissue samples – from all major organs, lymph nodes and the digestive tract – to look for evidence of problems due to xenotransplantation.

Experiments on the deceased cannot predict that the organs will function the same in the living, warned Karen Maschke, a researcher at the Hastings Center who is involved in developing ethical and policy recommendations for clinical xenotransplantation studies.

But they could also provide other valuable information, she said. That includes figuring out the differences between pigs with up to 10 genetic changes, which some research teams favor – and pigs like Montgomery, which have just a single change, the removal of a gene that triggers an immediate immune attack.

“The reason we do this is because, unfortunately, many people die before they have the chance for a second chance at life,” said Mangiola, the immunologist. “And we have to do something about it.”

The Associated Press Health and Science Department receives support from the Science and Educational Media Group of the Howard Hughes Medical Institute. The AP is solely responsible for all content.

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