Growing human transplant organs in pigs has become a more realistic prospect after scientists used advanced gene editing to remove threatening viruses from the animals' DNA.
Professor Darren Griffin of the University of Kent, who was not involved in the study, said the finding represents "a significant step forward towards the possibility of making xenotransplantation a reality".
An afternoon recap of the day's most important business news, delivered weekdays. In this latest work, scientists are working specifically with pig organs.
While there were 33,600 organ transplants in 2016, the 116,800 patients on organ transplant lists may not have to wait much longer.
In the 1990s, scientists began pursuing the idea in earnest.
These baby pigs were the first to be born without innate viruses in their DNA.
Specifically, porcine endogenous retroviruses (PERVs) can be carried in the genes of pigs even if they are not ill. Then, the researchers used CRISPR to edit the viral genome at 25 sites and deactivate the PERVs, so that they can't infect cells.
Clinical trials could occur two years from now, according to the genetics expert. Pig organs are quickly rejected by the body, causing severe immune reactions.
Next, the company needs to make sure it can consistently replicate virus-free pigs, which it's already well on its way to doing.
"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. "I think that such innovation is required to tackle as challenging a problem as xenotransplantation". Then the scientists cloned the edited cells. They allowed each egg to develop into an embryo and implanted it in the uterus of a surrogate mother.
Numerous porcine embryos and fetuses cloned in the CRISPR experiments died before birth or shortly after, but scientists ended up with 15 living female piglets, the oldest now 4 months old. None have the retroviruses.
But, this breakthrough, by boffins at biotech company eGenesis, could prove a major turning point.
However, there's no way those pig organs could actually be transplanted just yet, Ross says. To their shock, the baboon died in minutes.
They successfully transplanted hearts and kidneys from those pigs into monkeys and baboons.
An estimated 100 million pigs are killed in the United States each year for food, The New York Times reported.
Many patients may prefer a human organ, Cooper acknowledged, but that is not always possible.
According to Dr. David Klassen, Chief Medical Officer at the United Network for Organ Sharing, past year saw 33,600 organ transplants, with another 116,800 people listed on various lists waiting for sutiable organs.
But for that project, the researchers had used a line of "immortal" pig kidney cells, chosen for their ability to survive and divide indefinitely in a dish.