NEW YORK (AP) 鈥 Surgeons transplanted a pig鈥檚 kidney into a brain-dead man and for over a month it's worked normally 鈥 a critical step toward an operation the New York team hopes to eventually try in living patients.
Scientists around the country are racing to learn how to use , and offer a remarkable rehearsal.
The latest experiment announced Wednesday by NYU Langone Health marks the longest a pig kidney has functioned in a person, albeit a deceased one -鈥 and it鈥檚 not over. Researchers are set to track the kidney鈥檚 performance for a second month.
鈥淚s this organ really going to work like a human organ? So far it鈥檚 looking like it is,鈥 Dr. Robert Montgomery, director of NYU Langone鈥檚 transplant institute, told The Associated Press.
鈥淚t looks even better than a human kidney,鈥 Montgomery said on July 14 as he replaced a deceased man's own kidneys with a single kidney from a genetically modified pig 鈥 and watched it immediately start producing urine.
The possibility that pig kidneys might one day help ease a dire shortage of transplantable organs persuaded the family of Maurice 鈥淢o鈥 Miller from upstate New York to donate his body for the experiment. He'd died suddenly at 57 with a previously undiagnosed brain cancer, ruling out routine organ donation.
鈥淚 struggled with it,鈥 his sister, Mary Miller-Duffy, told the AP about her decision. But he liked helping others and 鈥淚 think this is what my brother would want. So I offered my brother to them.鈥
"He鈥檚 going to be in the medical books, and he will live on forever,鈥 she added.
Attempts at animal-to-human transplants, or xenotransplantation, have failed for decades as people's immune systems attacked the foreign tissue. Now researchers are using pigs genetically modified so their organs better match human bodies.
Last year with special permission from regulators, University of Maryland surgeons transplanted a gene-edited pig heart into a dying man who was out of other options. He survived only two months before the organ failed for reasons that but that offer lessons for future attempts.
Next, rather than last-ditch efforts, the 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 Wednesday, the University of Alabama at Birmingham reported another important success -- a pair of pig kidneys worked normally inside another donated body for seven days.
Kidneys don't just make urine 鈥 they provide a wide range of jobs 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 鈥減rovide life-sustaining kidney function.鈥
These kinds of experiments are critical to answer remaining questions 鈥渋n a setting where we鈥檙e not putting someone鈥檚 life in jeopardy,鈥 said Montgomery, the NYU kidney transplant surgeon who also received his own heart transplant 鈥 and is acutely aware of the need for a new source of organs.
More than 100,000 patients are on the nation's transplant list and thousands die each year waiting.
Maryland鈥檚 Dr. Muhammad Mohiuddin cautions that it鈥檚 not clear how closely a deceased body will mimic a live patient鈥檚 reactions to a pig organ. But he said the research educates the public about xenotransplantation so 鈥減eople will not be shocked鈥 when it鈥檚 time to try again in the living.
NYU and a team at the University of Alabama at Birmingham had tested pig kidney transplants in deceased recipients for just two or three days. An NYU team also had transplanted pig hearts into donated bodies for three days of intense testing.
But how do pig organs react to a more common human immune attack that takes about a month to form? Only longer testing might tell.
The surgery itself isn't that different from thousands he's performed 鈥渂ut somewhere in the back of your mind is the enormity of what you're doing ... recognizing that this could have a huge impact on the future of transplantation," Montgomery said.
The operation took careful timing. Early that morning Drs. Adam Griesemer and Jeffrey Stern flew hundreds of miles to a facility where Virginia-based Revivicor Inc. houses genetically modified pigs 鈥 and retrieved kidneys lacking a gene that would trigger immediate destruction by the human immune system.
As they raced back to NYU, Montgomery was removing both kidneys from the donated body so there'd be no doubt if the soon-to-arrive pig version was working. One pig kidney was transplanted, the other stored for comparison when the experiment ends.
One other trick: Surgeons attached the pig's thymus to the transplanted kidney in hopes that the gland, which helps train immune cells, would increase human tolerance of the organ. Otherwise, the team is relying on standard immune-suppressing drugs used by today's transplant patients.
鈥淵ou're always nervous,鈥 Griesemer said. To see it so rapidly kickstart, 鈥渢here was a lot of thrill and lot of sense of relief.鈥
How long should these experiments last? Alabama's Locke said that鈥檚 not clear -鈥 and among the ethical questions are how long a family is comfortable or whether it's adding to their grief. Because maintaining a brain-dead person on a ventilator is difficult, it鈥檚 also dependent on how stable the donated body is.
In her own experiment, the donated body was stable enough that if the study wasn鈥檛 required to end after a week, 鈥淚 think we could have gone much longer, which I think offers great hope," she said.
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AP video journalist Shelby Lum contributed to this report.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute鈥檚 Science and Educational Media Group. The AP is solely responsible for all content.
