Surgeons in New York have successfully attached a kidney
grown in a genetically altered pig to a human patient and found that the organ
worked normally, a scientific breakthrough that one day may yield a vast new
supply of organs for severely ill patients.
The procedure done at NYU Langone Health in New York City
involved use of a pig whose genes had been altered so that its tissues no
longer contained a molecule known to trigger an almost immediate rejection,
according to the Reuters news agency which reported on the news on Tuesday.
The recipient was a brain-dead patient with signs of kidney
dysfunction whose family consented to the experiment before she was due to be
taken off life support, researchers told the Reuters news agency.
For three days, the new kidney was attached to her blood
vessels and maintained outside her body, giving researchers access to it.
Test results of the transplanted kidney’s function “looked
pretty normal,” said transplant surgeon Dr Robert Montgomery, who led the
study.
The kidney made “the amount of urine that you would expect”
from a transplanted human kidney, he said, and there was no evidence of the
vigorous, early rejection seen when unmodified pig kidneys are transplanted
into non-human primates.
The recipient’s abnormal creatinine level – an indicator of
poor kidney function – returned to normal after the transplant, Montgomery
said.
In the United States, nearly 107,000 people are currently
waiting for organ transplants, including the more than 90,000 awaiting a
kidney, according to the United Network for Organ Sharing. Stand-by times for a
kidney average between three and five years.
Researchers have been working for decades on the possibility
of using animal organs for transplants, but have been stymied over how to
prevent immediate rejection by the human body.
Montgomery’s team theorised that knocking out the pig gene
for a carbohydrate that triggers rejection – a sugar molecule, or glycan,
called alpha-gal – would prevent the problem.
The genetically altered pig, dubbed GalSafe, was developed
by United Therapeutics Corp’s Revivicor unit. It was approved by the US Food
and Drug Administration (FDA) in December 2020, for use as food for people with
a meat allergy and as a potential source of human therapeutics.
Medical products developed from the pigs would still require
specific FDA approval before being used in humans, the agency said.
Other researchers are considering whether GalSafe pigs can
be sources of everything from heart valves to skin grafts for human patients.
The NYU kidney transplant experiment should pave the way for
trials in patients with end-stage kidney failure, possibly in the next year or
two, said Montgomery, himself a heart transplant recipient. Those trials might
test the approach as a short-term solution for critically ill patients until a
human kidney becomes available, or as a permanent graft.
The current experiment involved a single transplant, and the
kidney was left in place for only three days, so any future trials are likely
to uncover new barriers that will need to be overcome, Montgomery said.
Participants would probably be patients with low odds of receiving a human
kidney and a poor prognosis on dialysis.
“For a lot of those people, the mortality rate is as high as
it is for some cancers, and we don’t think twice about using new drugs and
doing new trials (in cancer patients) when it might give them a couple of
months more of life,” Montgomery said.
The researchers worked with medical ethicists, legal and religious experts to vet the concept before asking a family for temporary access to a brain-dead patient, Montgomery said. -Reuters
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