Researchers have figured out a way to make pig organs for human beings free of dangerous viruses using a controversial gene-editing technique. The finding sets the stage for transplanting pig organs into humans, as well as the possibility of using gene-editing to engineer a disease-free human.
The finding reported this week by Harvard University researchers in the journal Science Express uses a technology known as CRISPR/Cas-9, which acts as a super-accurate pair of scissors for editing individual bits of DNA.
"It's a really exciting possibility because it has immediate applications for transplantation, but also the longer-term proof of concept of something that would be hard to test in humans," said George Church, professor of genetics at Harvard University and an author on the paper published this week in Science Express.
Some critics worry that CRISPR gene editing could lead to "designer babies" by altering the DNA of human embryos directly to produce children with certain desirable traits. However, most experts say a more likely scenario will be using the technology to eliminate genes that cause inherited diseases like Parkinson's or Huntington's, for example.
"Some people will say ‘I'd like to have my own genetically modified kid. I don't want a donor egg or adoption but I do have Huntingtons or Tay-Sachs or some other miserable disease,'" said Arthur Caplan, professor of bioethics at New York University. "Someone will say let's try to engineer embryos to see if we could produce a healthy child."
That possibility is still several years away, Caplan noted. But in the meantime, work is progressing rapidly on using CRISPR in animal models like mice, pigs and monkeys in order to see how well it works.
The shortage of organs for transplantation is a major barrier to the treatment of organ failure. While scientists say they would like to use more pig organs, there are fears about transmission of porcine endogenous retroviruses (PERVs) to humans. In the Science paper, postdoctoral student Luhan Yang and Church were able to eliminate 62 of these retroviruses in a pig kidney cell line.
The researchers say they have to see that the technique works in the living animal itself, then test it in human cells before moving on to human clinical trials.
"You need to gradually monitor its use to bring it into humans," Caplan said. "It's like any other application, you want to test it in animals first."
Many labs across the United States are using CRISPR on various animal cell lines, but so far, its use in human embryos is prohibited by researchers that accept funding from the National Institutes of Health. That prohibition does not exist in China, where scientists can create human embryos to work on various gene editing experiments. Still, Caplan expects a gene-edited human to come from the private world rather than a university or government-funded lab.
"We are a country that doesn't do much to regulate privately funded activities," Caplan said. "That is one other reason you can sense a CRISPR race between us, the Chinese and other places."
Church also is co-founder of the biotech firm Editas Medicine. He said he expects the company will enter clinical trials next year on a gene-editing process for humans.