Pig to Human Kidney Transplantation

Borek Transplantation from Pig to Human
Surgeons preparing pig kidneys for transplant - Jeff Myers, UAB

Two pig kidneys, genetically engineered to avoid rejection by the immune system, were transplanted into a brain-dead man as the first step in treating the patients. The kidneys were not rejected during the 77 hours that the experiment in the USA lasted. "This game-changing moment marks an important milestone in the field of xenotransplantation, arguably the best solution to the organ shortage crisis," surgeon Jayme Locke of the University of Alabama at Birmingham said in a statement. The aim of the study is to pave the way for a clinical trial that Locke hopes will begin later this year. We can touch on the details of our article "Pig Transplantation from Pig to Human".

Buyer Jim Parsons was injured during a motorcycle race. He was a registered organ donor, but none of his organs were suitable for transplantation. His family allowed his body to be kept alive on the ventilator so that the study could be carried out. His own kidneys were removed and replaced with genetically modified pig kidneys. “As a family, we had no doubt that Jim would want this,” his ex-wife said at the press briefing.

The experiment took place on September 30, but the details were revealed in a paper published today. The kidneys came from the same genetically modified pigs as the heart, which was transplanted to David Bennett on January 7. Bennett received the pig heart as there were no other options for him, while the kidney transplant was done only as an initial safety test.

Surgeon Locke said at the briefing that while the idea of ​​testing therapies in people with brain death had been proposed before, his team was the first to do so. The Parsons model could be valuable in situations where animal testing isn't enough, his team said.

Why Play With The Genetics Of Pig Kidneys?

Even if humans have been given immunosuppressive drugs, pig organs cannot normally be transplanted into humans as they are rejected by the human immune system. But the pigs created by the US firm Revivicor have been genetically modified to avoid rejection.

Four genes were disabled, some of which encode proteins that trigger the immune response in humans. Pigs also have six additional human genes.

Pig kidneys were not rejected during the 77 hour experiment. “He started urinating within 23 minutes,” Locke said, referring to the first of two pig kidneys transplanted. “This is a remarkable achievement. We had a beautiful pink kidney, not a kidney that turned black from hyperacute rejection.”

However, while the kidneys were producing urine, they did not remove a substance called creatinine, which is an important measure of normal kidney function, from the blood. The team isn't sure why this is the case, but it may be related to Parsons' situation.

One potential problem is that pigs have lower blood pressure than humans.

This means that blood vessels in pig kidneys can be damaged by higher blood pressure after transplantation. However, the team did not see any signs of trouble.

Another concern is that virus genes hidden in pigs' genomes could infect humans, but the team found no trace of it. But at least one other company trying to create pigs suitable for transplant is deleting all viral genes to ensure this doesn't happen.

Locke said at the briefing that a kidney transplant is a cure for chronic kidney disease, but most people die before they can get one. There are about 100.000 people on the waiting list for transplants in the United States, but fewer than 25.000 transplants are performed each year.

Source: newscientist

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