The pig, the future reservoir of organs for transplantation?

• American scientists have successfully transplanted the kidney from a pig to a human.

• If the results of this world first are confirmed, it could pave the way for a new organ reservoir to meet the needs of patients awaiting transplants.

• But this discovery has yet to be examined and validated by the scientific community.

  Not to mention the ethical questions raised by this possibility.

A world first full of hope.

American scientists have succeeded in making the kidney of a pig work on a human.

The operation was carried out at NYU Langone Hospital in New York on September 25, using the kidney of a genetically modified pig, so that the organ was not rejected by the human body.

Kidneys, lungs, hearts… Could this experiment sign the imminent generalization of pig organ transplants in humans?

Could we see the emergence of farms in which genetically modified pigs are raised for the sole purpose of providing organs to humans awaiting transplants?

covers the (many) questions raised by this operation.

Will the transplant recipient live with a pig kidney?

This kidney was not strictly speaking implanted inside a human body, but connected to the blood vessels of a patient in a state of brain death, whose family had authorized the experiment, at the level of the top of his leg.

The kidney “worked well” during the 54 hours of the experiment, said Robert Montgomery, director of the NYU Langone Institute of Transplantation.

“He did what he was supposed to do, (…) he produced urine”.

“It was better than we expected,” he added.

“It looked like any transplant I have done from a living donor.

Many kidneys of people who have died do not work right away and take days or weeks to start.

There, it worked immediately ”.

And "the fact that the organ was functioning outside the body is a strong indication that it would be functioning in the body," he said.

Why are scientists turning to pork organs?

And why are pigs genetically modified?

This is nothing new, as researchers have long sought to cultivate porcine organs that might be suitable for transplantation in humans. Cloning and genetic engineering are the avenues that have made this hypothesis tangible in recent years. "Some pig organs have a size and function similar to those of humans", pointed out in September 2017 researchers from Harvard University, in a study published in the journal 

. “In the face of the severe shortage of organs for transplants, xenotransplantation - the transplantation of non-human organs into humans - offers an alternative source,” they argued. They then announced the possibility of transplanting organs from pigs to humans. At the time, the group of scientists set out to modify a DNA fragment to inactivate endogenous retroviruses housed in the pig genome. A successful trial which, as part of their experimentation, had made it possible to prevent the systematic rejection of porcine tissue by the human body.

But this is not the only obstacle.

The human body for its part contains antibodies attacking a type of sugar normally present "on all pig cells", which causes "immediate rejection" of the organ, explained Robert Montgomery.

To counter this phenomenon, the animal was this time genetically modified to no longer produce this sugar and there was no “rapid kidney rejection” observed.

Can pig organ transplantation in humans become a reality in the future?

If success is confirmed, genetically modified pigs "could potentially be a sustainable and renewable source of organs," said Dr Robert Montgomery. This world first represents "a major hope", estimated on Franceinfo Professor Olivier Bastien, specialist in transplantation and former director of the activity of organ harvesting and transplants at the Biomedicine Agency. But many experts call for caution, as the detailed results of the study conducted have not yet been published in a leading scientific journal. An important step to assess whether the results described by American researchers are reproducible. "It is nevertheless an interesting step on the road leading to the use of genetically modified pigs as a source of organs for transplants",commented Alan Archibald, genetics specialist at the University of Edinburgh.

In addition, this assumption raises ethical questions. While issues related to animal welfare and exploitation have taken center stage in public debate, the prospect of raising genetically modified pigs for the purpose of making them an organ reservoir is far from over. unanimity. "Pigs are not spare parts and should never be used as such simply because humans are too egotistical to donate their bodies to patients desperate for organ transplants," the US branch said in a statement. from PETA.

But for patients waiting for a transplant, this experiment is hopeful.

According to a survey by the France Transplant association on kidney transplants published in early 2020, in France alone, "500 to 600 patients registered on the waiting lists die each year, for lack of having been transplanted".

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