Surgeons successfully transplant a PIG KIDNEY into a human, marking a ‘significant step’ in the decades-long quest to use animal organs for life-saving transplants
- Surgeons have successfully transplanted a pig kidney into a human for first time
- Huge step in decades-long quest to use animal organs for life-saving transplants
- Pig’s genes altered so tissues didn’t contain molecule known to trigger rejection
- Recipient was brain-dead patient in New York whose family agreed to procedure
Surgeons in the US have successfully transplanted a pig kidney into a human for the first time.
It started working as it was supposed to by filtering waste and producing urine without triggering a rejection by the recipient’s immune system.
The procedure, which was carried out at NYU Langone Health in New York, marks a ‘significant step’ in the decades-long quest to use animal organs for life-saving transplants.
It involved the use of a pig whose genes had been altered so that its tissues no longer contained a molecule known to trigger almost immediate rejection.
The recipient was a brain-dead patient with signs of kidney dysfunction whose family agreed to the experiment before she was due to be taken off life support, researchers said.
Surgeons in the US have successfully transplanted a pig kidney into a human for the first time
HOW WAS A PIG KIDNEY ATTACHED TO A HUMAN?
Surgeons have successfully transplanted a pig kidney into a human for the first time without it triggering a rejection by the recipient’s immune system.
The procedure involved the use of a pig whose genes had been altered so that its tissues no longer contained a molecule known to trigger almost immediate rejection.
Dr Robert Montgomery, who led the study, theorised with his team that knocking out the pig gene for a carbohydrate that triggers rejection — a sugar molecule, or glycan, called alpha-gal — would prevent the issue.
To do this, a pig embryo with one gene modified was implanted inside a surrogate sow by United Therapeutics Corp’s Revivicor unit.
The sow then delivered a piglet with a modified immune system more compatible with humans.
Once an adult, the pig also had surgery to attach its thymus to its kidney. The thymus is a small gland near the top of the lungs, which produces white blood cells.
Transplanting the pig thymus along with its kidney is aimed at reducing a person’s long-term immune response to the foreign kidney.
Surgeons then attached the organ to the human recipient’s thigh, giving researchers access to it.
In theory, the patient’s thymus would then be removed.
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 UK, more than 6,100 people are waiting for an organ transplant, according to the latest figures from this month, including 4,584 patients waiting for a kidney.
In the US, nearly 107,000 people are currently waiting for organ transplants, including more than 90,000 awaiting a kidney, according to the United Network for Organ Sharing. Wait times for a kidney average three-to-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 believed that knocking out the pig gene for a carbohydrate that triggers rejection — a sugar molecule, or glycan, called alpha-gal — would prevent the problem.
To do this, a pig embryo with one gene modified was implanted inside a surrogate sow by United Therapeutics Corp’s Revivicor unit.
The sow then delivered a piglet with a modified immune system more compatible with humans.
Once an adult, the pig also had surgery to attach its thymus to its kidney. The thymus is a small gland near the top of the lungs, which produces white blood cells.
Transplanting the pig thymus along with its kidney is aimed at reducing a person’s long-term immune response to the foreign kidney.
Surgeons then attached the organ to the human recipient’s thigh, giving them access to it for monitoring.
The genetically altered pig, dubbed GalSafe, was approved by the US Food and Drug Administration 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 procedure, which was carried out at NYU Langone Health in New York, marks a ‘significant step’ in the decades-long quest to use animal organs for life-saving transplants
It involved the use of a pig whose genes had been altered so that its tissues no longer contained a molecule known to trigger almost immediate rejection
The recipient was a brain-dead patient with signs of kidney dysfunction whose family agreed to the experiment before she was due to be taken off of life support, researchers said
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,’ said Montgomery.
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, he added.
HOW DO SCIENTISTS CREATE GENETICALLY MODIFIED PIG EMBRYOS?
To grow a human organ in an animal embryo, a researcher from the University of California, Davis uses new gene-editing techniques, according to NPR.
With a small laser, researchers can cut a small hole in the outer layer of the embryo’s membrane.
Then, they inject a synthesized molecule that can ‘delete’ the pancreas gene.
Once the DNA has been edited, they then make another hole in the membrane to inject human induced pluripotent stem cells (iPS).
These are made from the skin of an adult human, and would reduce the risk of transplant rejection.
The cells can turn into any kind of cell or tissue in the human body, and in a pig embryo, they have the same capabilities.
Scientists have been studying how ‘model animals’ with transplantable organs can save humans’ lives for years. They’ve used sheep, pigs, cows and rats as subjects. File photo
But, it means they could go anywhere else in the body, including the brain.
The researchers hope that the cells will work to take the place of the removed gene in the embryo to create a human pancreas.
Once the iPS cells have been injected, the now-chimera embryo is surgically placed into the womb of an adult pig.
The embryos are allowed to develop until their 28th day, when primitive structures begin to form, and then they are retrieved and dissected.
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