A pig’s kidney transplanted into a brain-dead man is still functioning normally after more than a month, a critical step towards an operation the New York team hopes to eventually try in living patients, they said.
The latest experiment by New York University Langone Health marks the longest a pig kidney has functioned in a person, albeit a deceased one, reports The Guardian.
“Is this organ really going to work like a human organ? So far it’s looking as if it it is,” said Dr Robert Montgomery, director of NYU Langone’s transplant institute.
“It looks even better than a human kidney,” he had said on 14 July as he replaced the deceased man’s own kidneys with a single kidney from a genetically modified pig – and watched it immediately start producing urine.
Scientists are racing to learn how to use animal organs to save human lives, and bodies donated for research offer a remarkable rehearsal. More than 100 000 patients are on the nation’s transplant list; thousands die each year waiting.
The possibility that pig kidneys might one day help ease a dire shortage of transplantable organs persuaded the family of Maurice Miller (57) from New York to donate his body for the experiment.
“I struggled with it,” said his sister, Mary Miller-Duffy. “But he liked helping others and I think this is what he would want.”
Attempts at animal-to-human transplants 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 as a final attempt to save a dying man. He survived only two months before the organ failed for reasons that aren’t fully understood but that offer lessons for future attempts.
The US Food and Drug Administration is now considering whether to allow some small 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 last week, the University of Alabama at Birmingham (UAB) reported another important success – a pair of pig kidneys worked normally inside another donated body for seven days.
Kidneys perform a wide range of jobs in the body beyond making urine. In the journal Jama Surgery, the UAB transplant surgeon Dr Jayme Locke reported lab tests documenting the gene-modified pig organs’ performance. She said the weeklong experiment demonstrated they could “provide life-sustaining kidney function”.
These experiments are critical to answer more remaining questions “in a setting where we’re not putting someone’s life in jeopardy”, said Montgomery, the NYU kidney transplant surgeon, who also received his own heart transplant – and is acutely aware of the need for a new source of organs.
The surgery itself isn’t that different from thousands he’s performed “but somewhere in the back of your mind is the enormity of what you’re doing … recognising that this could have a huge impact on the future of transplantation”, he said.
The operation took careful timing. Early that morning doctors Adam Griesemer and Jeffrey Stern boarded a flight to a facility where the Virginia-based Revivicor Inc houses genetically modified pigs – 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 were working. One pig kidney was transplanted, the other stored for comparison when the experiment ends.
“You’re always nervous,” Griesemer said. “To see it so rapidly kickstart was a thrill and a relief.”
How long should these experiments last? Alabama’s Locke said that’s not clear, and among the ethical questions are how long a family is comfortable and whether it’s adding to their grief. Because maintaining a brain-dead person on a ventilator is difficult, the decision is also dependent on how stable the donated body is.
In her own experiment, the donated body was stable enough that if the study weren’t required to end after a week, “I think we could have gone much longer, which offers great hope”, she said.
JAMA Surgery article – Normal Graft Function After Pig-to-Human Kidney Xenotransplant (Open access)
See more from MedicalBrief archives:
Pig heart used in US transplant may have been infected with porcine virus
World first: Transplant of pig heart on terminal US patient
Gene-edited piglets opening door to animal organ transplants