Gene editing breakthrough could pave way for pig-to-human organ transplants

Henrietta Brewer
August 11, 2017

A scientific advance using genetically edited piglets could lower the fatality rate and make using pig organs, similar to our own, a common practice. The presence of these PERVs means pig organs can not now be safely transplanted into humans.

According to Dr. David Klassen, Chief Medical Officer at the United Network for Organ Sharing, a year ago saw 33,600 organ transplants, with another 116,800 people listed on various lists waiting for sutiable organs.

According to the US Health Resources and Services Administration, there are more than 118,000 people in the US who are on the waiting list for organ transplants.

This is the first time researchers have been able to demonstrate they were able to inactivate PERV and open the way for xenotransplantation (the act of transplanting animal organs to humans) without cross-species contamination. Two early developers of that gene-editing technology, Harvard University geneticists George Church and Luhan Yang, suspected that CRISPR's highly efficient duo of guide RNA and a DNA-slicing enzyme could make precise, genome-wide changes to pig cells. The idea of using pigs as organ factories has tantalized investigators for decades.

These baby pigs were the first to be born without innate viruses in their DNA. Alternatively, human cells populating the germline of an animal could enable human genes to pass onto offspring.

Researchers in the United States used the precision gene editing tool Crispr-Cas9 combined with gene fix technology to deactivate 100% of Pervs in a line of pig cells.

Dr. David Klassen told The New York Times that if pig organs were safe and effective to transplant into humans "they could be a real game changer". "I think that such innovation is required to tackle as challenging a problem as xenotransplantation".

PERVs have been shown to infect human cells and previous research has shown the horizontal transfer of PERVs among human cells. But Church and his colleagues ended up with 15 living piglets, the oldest now 4 months old. And eGenesis's lab tests did not prove the viruses would be a risk to patients, says Muhammad Mansoor Mohiuddin, a professor of surgery and director of Xenoheart Transplantation at the University of Maryland School of Medicine, who was not part of the new study. That's because there's another major problem with xenotransplantation that this paper doesn't address: the danger of organ rejection.

Researchers soon discovered that pig organs are covered with carbohydrate molecules that mark the organs for immediate destruction by human antibodies. And, he said, the pigs would be anesthetized and killed humanely.

More than 1,000 people die in Britain each year waiting for a transplant. As a result, Church had wondered if they play an essential role in the pig's survival and whether the animals could develop properly without them.

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