Scientists have taken a major step toward enabling pig to human organ transplantation by using a novel gene editing technology known as CRISPR-Cas9.
Pig organs are the same size as human organs and function pretty much the same way but pig to human transplantation has always been an elusive goal for researchers due to fear of activating dormant viral diseases in the pig's cells.
There were 33,600 organ transplants previous year, and 116,800 patients on waiting lists, according to Dr. David Klassen, chief medical officer at the United Network for Organ Sharing, a private, nonprofit organization that manages the nation's transplant system.
While there were 33,600 organ transplants in 2016, the 116,800 patients on organ transplant lists may not have to wait much longer.
However, one step must still be overcome before pig-to-human transplants are viable.
Now eGenesis, spun out of Harvard geneticist George Church's lab, may have figured out how to get rid of these species-jumping viruses. Once infected, the human cells were able to infect other human cells.
To overcome this, researchers used the CRISPR-Cas9 gene-editing technique to inactivate all the PERVs in a porcine primary cell line and generated PERV-inactivated pigs through somatic cell nuclear transfer.
The next stage of the research, Church and Yang say, will be to essentially "humanize" the pigs-modifying them enough that their organs can function in the human body. "I think the risk to society is very low".
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.
The study was partly funded and conducted by the biotech company eGenesis.
Other teams, including Tector's at Alabama, are working along a similar path, hoping to get the pig parts ready to be tested in the first people within the next two to three years.
Scientists have been introducing human cells into animals to create models of diseases for decades, yet the 2009 policy suspended funding for chimera-based research due to ethical concerns. In 1984, "Baby Fae" famously received a heart transplant from a baboon and died 20 days later. He and his colleagues recently attempted to chop PERV genes out of pig cells with an editing technology called zinc finger nucleases, but the many imprecise DNA cuts proved toxic to cells. So far, the resulting animals are healthy and virus-free.
To some, the idea of growing pigs to be organ factories is distasteful, if not unethical.
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. In this latest work, scientists are working specifically with pig organs.