"It's an elegant tour de force of genetic engineering, so my hat is off to them", A. Joseph Tector, of the University of Alabama, Birmingham, who has also made genetically modified pigs aimed at producing transplantable organs, told Stat News.
The world has a big organ shortage problem: nearly 120,000 people are now waiting for a transplant in the USA, and more than 20 people die each day waiting for a new organ.
Dr. David Cooper, at UAB, and his colleagues, including Tector, have used gene editing and cloning to make pigs without the carbohydrates on the surfaces of their organs.
Today scientists in MA announced that by using the CRISPR-Cas9 gene-editing system they were able to inactivate all 25 viruses in the pig genome, yielding seemingly healthy piglets and moving research one step closer to a future of xenotransplantation.
"We generated a protocol to enable multiplex genome editing, eradicated all Perv activity using Crispr technology in cloneable primary porcine fibroblasts and successfully produced Perv-free piglets. I think that such innovation is required to tackle as challenging a problem as xenotransplantation".
Using organs from another animal "is a promising strategy to alleviate the shortage of organs for human transplantation", the study notes, but one major concern is illnesses that could be transmitted from pigs to humans.
"We got perfectly healthy piglets", Church tells The Verge, "so that's fantastic". The retroviruses don't harm pigs, but would make xenotransplants, cross-species transplants, impossible.
Formidable obstacles remain "in overcoming immunological rejection and physiological incompatibility of pig organs in humans", he said. As the New York Times reports, researchers have wanted to explore using pigs as organ sources in the past, but plans were thwarted by the fear that viruses from the pigs, called retroviruses, could infect humans through the transplants. The viruses could then be transmitted to other cells not exposed to pig tissue. The presence of these PERVs means pig organs can not now be safely transplanted into humans.
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. Some of these piglets are still growing, says Yang, and they're still healthy.
It's not known if Pervs could actually cause diseases in humans but they are an unacceptable risk.
Experiments showed pig cells could infect human cells with Pervs in the lab.
They identified - and switched OFF - 25 different viruses in the pigs' DNA, known by their scientific name porcine endogenous retroviruses (Pervs for short).
The team managed to remove those viruses, but that doesn't mean that the organ crisis has been solved yet. If this happened, it may cause diseases like cancer.
Still, Tector says, if the FDA does require the viruses to be removed, then the eGenesis team's approach will be useful. Still, Denner says, "If it is possible to knock [PERVs] out, you should do it".