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First Pig-to-Human Organ Transplants 2 Years Away, Say Scientists

13 Agosto 2017

Scientists in decades past experimented with transplanting chimpanzee organs into human patients but turned their focus to pig organs instead after finding them to be more suitable donor candidates.

As STAT reports, out of 37 piglets, all were born without retroviruses.

Speaking to the New York Times, Dr. David Klassen, chief medical officer at the United Network for Organ Sharing, a nonprofit organization that manages the U.S. transplant system, said the study "could be a real game changer".

The WHO says while animals are a potential source of high quality, readily available live organs, xenotransplantation carries risks, especially the spread of known or unknown diseases.

There is a significant shortage of human organs and tissues for transplant-more than 116,000 people are waiting for a lifesaving organ transplant, according to the Department of Health and Human Services.

Pigs show potential as organ donors for humans as their organs are similar in size and function and they can be bred in large numbers.

But making 25 cuts throughout the pig's genome led to DNA instability and the loss of genetic information. Using this technique they were able to successfully remove all retroviruses from the pig cells.

Harvard University geneticists George Church and Luhan Yang, together with a team of Danish and Chinese collaborators, placed edited embryonic cells into a chemical cocktail that encouraged growth and overcame the destructive effect inherent in the modification process. But doctors have used some pig parts - like heart valves or pancreas cells - as replacements in humans before and there was no evidence of infection in those cases.

With modified genes, the scientists created PERV-inactivated pig embryos and transferred them into surrogate sows to produce clones, in the same fashion as Dolly the sheep was created. Knocking out three in particular could protect pig organs from being attacked by the human immune system, he said; lab macaques that received kidneys from the pigs have survived as long as 499 days. In this latest work, scientists are working specifically with pig organs.

He said: "The viruses are particularly troubling".

"We're talking about some dramatic advances and literally happening week by week, but they can keep going". Just last week, US scientists were able to demonstrate they could successfully CRISPR out a faulty heart gene mutation in human embryos.

Prof Ian McConnell, from the University of Cambridge, said: "This work provides a promising first step in the development of genetic strategies for creating strains of pigs where the risk of transmission of retroviruses has been eliminated. But the use of animal organs such as pig kidneys and hearts is not without serious ethical and biosecurity concerns".

First Pig-to-Human Organ Transplants 2 Years Away, Say Scientists