US researchers test pig-to-human transplant in donor body

Researchers on Thursday reported the latest in a surprising series of experiments in a quest to save lives with organs from genetically engineered pigs.

This time, surgeons in Alabama transplanted a pig’s kidney into a brain-dead man — a step-by-step rehearsal for an operation they hope to try in living patients with possibly by the end of this year.

Dr Jayme Locke of the University of Alabama at Birmingham, who led the latest study and aims to start the clinical trial in pigs, said: “The organ shortage is in fact an insoluble crisis. can decide. kidney transplant.
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Similar experiments have hit the headlines in recent months as research on animal to human transplant heated up.

Twice this fall, surgeons at New York University temporarily attached a pig kidney to blood vessels outside the body of a deceased person to see them work. And earlier this month, surgeons at the University of Maryland Medical Center gave a dying man a heart from a gene-edited pig that has so far kept him alive. .

But scientists still need to learn more about how to test such transplants without endangering the patient’s life. With the help of a family that donated a loved one’s body to science, Locke mimicked human organ transplants — from removing the “donor’s” pig’s kidneys to stitching them into the deceased’s abdomen.

For a little more than three days, until the man’s body was taken out life support, the pig kidneys survived with no immediate signs of rejection, her team reported Thursday in American Journal of Transplantation.

That’s just one of the key findings. Locke says it’s not clear whether the fragile pig kidney blood vessels can withstand the pulsating force of human blood pressure – but they did. One kidney was damaged during the caesarean section and didn’t function properly, but the other kidney quickly started producing urine like a kidney. No swine virus was transmitted to the recipient and no pig cells were found in his blood.

But Locke said the kidney experiment could have more far-reaching implications – because it shows that a brain cadaver could be a much-needed human model for testing potential new medical treatments. power.

The study was conducted in September after Jim Parsons, a 57-year-old Alabama man, was pronounced brain dead from a mountain bike accident.

After hearing this kind of research “has the potential to save hundreds of thousands of lives, we definitely know that it is something Jim will definitely put his stamp of approval on,” said Julie O’Hara, the former lover of Parsons said. wife.

The need for another source of organs is huge: While more than 41,000 transplants were performed in the US last year, a record, more than 100,000 people remain on the nation’s waiting list. Thousands of people die each year before their organs are harvested, and thousands more are never even added to the list, which is considered far-fetched.

Pig transplant
University of Alabama at Birmingham / APIn this photo provided by the University of Alabama at Birmingham, surgeons check to see if the kidney of a genetically modified pig is working in the body of a person who died in September 2021. The test procedure is a step-by-step drill for operations they hope to try in living patients possibly by the end of 2022, part of a mission to use animal organs to save lives.

Animal-to-human transplants, known as xenotransplant transplants, have been attempted unsuccessfully for decades. The human immune system almost immediately attacks foreign tissues. But scientists now have new techniques for editing pigs’ genes to make their organs more human — and some are anxious to try again.

Dr David Kaczorowski of the University of Pittsburgh Medical Center said the recent series of experiments on pigs “is a huge step forward”. The move to early-stage testing in dozens of people is likely to “become more and more possible.”

A heart transplant surgeon, Kaczorowski has performed experiments examining pig organs in non-human primates that help pave the way, but “there are only things we can learn by transplanting them into the body.” people”.

Karen Maschke, a research scholar at the Hastings Center who will help develop ethical and policy recommendations for the first clinical trials under funding from the Hastings Center, there are still hurdles before begin formal human trials, including deciding who will be eligible to test pig organs. Medical Institute.

NYU Langone Health’s Dr. Robert Montgomery, who led that center’s kidney experiments in the fall, said scientists still have a lot to learn about how long pig organs last and how best to genetically modify them.

“I think different agencies will require different gene edits,” he said in an email.

For the latest kidney experiment, UAB partnered with Revivicor, a subsidiary of United Therapeutics, which also supplied organs for the recent heart transplant in Maryland and the kidney experiment in New York. The company’s scientists made 10 genetic changes to these pigs, removing some of the genes that trigger human immune attack and cause the animals’ organs to grow too large – and added some human genes to make the organs look less foreign to the human immune system.

Then there are practical questions like how to minimize the time spent working pig organs to their destination. UAB has placed the transplanted pigs in a germ-free facility in Birmingham complete with an operating room-like space for the organs to be harvested and ready for transplantation.

Revivicor chief scientific officer David Ayares said future plans include building more such facilities near transplant centers.

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