For the first time, scientists have edited DNA in human embryos, a highly controversial step long considered off limits.
Junjiu Huang and his colleagues at the Sun Yat-sen University in Guangzhou, China, performed a series of experiments involving 86 human embryos to see if they could make changes in a gene known as HBB, which causes the sometimes fatal blood disorder beta-thalassemia.
The report, in the journal Protein & Cell, was immediately condemned by other scientists and watchdog groups, who argue the research is unsafe, premature and raises disturbing ethical concerns.
"No researcher should have the moral warrant to flout the globally widespread policy agreement against modifying the human germline," Marcy Darnovsky of the Center for Genetics and Society, a watchdog group, wrote in an email to Shots. "This paper demonstrates the enormous safety risks that any such attempt would entail, and underlines the urgency of working to forestall other such efforts. The social dangers of creating genetically modified human beings cannot be overstated."
George Daley, a stem cell researcher at Harvard, agreed.
"Their data reinforces the wisdom of the calls for a moratorium on any clinical practice of embryo gene editing, because current methods are too inefficient and unsafe," he wrote in an email. "Further, there needs to be careful consideration not only of the safety but also of the social and ethical implications of applying this technology to alter our germ lines."
Scientists have been able to manipulate DNA for years. But it's long been considered taboo to make changes in the DNA in a human egg, sperm or embryo because those changes could become a permanent part of the human genetic blueprint. One concern is that it would be unsafe: Scientists could make a mistake, which could introduce a new disease that would be passed down for generations. And there's also fears it this could lead to socially troubling developments, such as "designer babies," in which parents can pick and choose the traits of their children.
The Chinese researchers say they tried this to try to refine a new technique called CRISPR/Cas9, which many scientists are excited about it because it makes it much easier to edit DNA. The procedure could enable scientists to do all sorts of things, including possibly preventing and curing diseases. So the Chinese scientists tried using CRISPR/Cas9 to fix a gene known as the HBB gene, which causes beta thallasemia.
The work was done on 86 very early embryos that weren't viable, in order to minimize some of the ethical concerns. Only 71 of the embryos survived, and just 28 were successfully edited. But the process also frequently created unintended mutations in the embryos' DNA.
"Taken together, our data underscore the need to more comprehensively understand the mechanisms of CRISPR/Cas9-mediated genome editing in human cells, and support the notion that clinical applications of the CRISPR system may be premature at this stage," the Chinese scientists wrote.
Rumors about this research have been circulating for weeks, prompting several prominent groups of scientists to publish appeals for a moratorium on doing this sort of thing.
In the wake of the report from the Chinese scientists, several of these researchers reiterated their call for a moratorium. Some said they hoped the difficulties that Huang and his colleagues encountered might discourage other scientists from attempting anything similar.
"The study simply underscores the point that the technology is not ready for clinical application in the human germline," Jennifer Doudna, the University of California, Berkeley, scientist who developed CRISPR, wrote in an email. "And that application of the technology needs to be on hold pending a broader societal discussion of the scientific and ethical issues surrounding such use."
But there are already reports that Huang's group and possibly others in China continue to try editing the genes in human embryos.
"We should brace for a wave of these papers, and I worry that if one is published with a more positive spin, it might prompt some IVF clinics to start practicing it, which in my opinion would be grossly premature and dangerous," Daley says.
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STEVE INSKEEP, HOST:
Scientists in China face accusations that they crossed an ethical line. That's because of what they did with human embryos. The scientists claim to have edited the DNA in human embryos. The reason was to see if they could prevent future health problems. NPR health correspondent Rob Stein has been following the story. He's in our studios. Rob, good morning.
ROB STEIN, BYLINE: Good morning.
INSKEEP: So what exactly did they do?
STEIN: Yeah, Steve, this is a group of scientists at Sun Yat-sen University in Guangzhou - that's in southern China. And they used a new technique for editing DNA for doing genetic engineering to try to fix a gene that causes a blood disorder that can be fatal sometimes called beta-thalassemia.
INSKEEP: OK - Sounds like a well-intentioned idea. What's wrong with it?
STEIN: Well, this is hugely controversial, and here's why. You know, scientists have been able to manipulate DNA to do genetic engineer for a long time now. But there's always been one thing that's been considered taboo, off-limits. And that's changing the DNA inside a human sperm, a human egg or a human embryo. And the reason is if you do that, whatever change you make can be passed down for generations. And there are lots of reasons not to do that. One is you can make some kind of mistake. You could end up...
INSKEEP: Unintended consequences, sure.
STEIN: Exactly. And you end up creating a new disease that would then be passed down for generations. And the other concern is sort of the bigger societal concern that this sort of thing could be sort of a slippery slope towards all kinds of, like, "Brave New World" kinds of things, including making designer babies, where parents can pick the traits of their children to be smarter or taller or better athletes and, you know, essentially, genetically engineering the human race.
INSKEEP: Yeah, changing what it means to be human. Although the scientists say they were just trying to deal with this medical issue. Did their effort actually work?
STEIN: Well, they say they did this because there's this new technique that I mentioned. It's a new technique. It's called CRISPR, which makes it much easier to do very precise changes in human DNA. And scientists are really excited about this because it could lead to all sorts of good things and ways to prevent human diseases from occurring. And the scientists say, you know, if we're going to eve try to do that, we need to try it and see if it works.
And so, as I said, they tried to fix a gene called the HBB gene which causes that blood disease I mentioned earlier. And, you know, they did this on embryos that weren't viable, meaning that if you ever tried to put them inside of a woman's womb, they wouldn't survive. And that was to try to address some of these ethical issues that I mentioned earlier. And they tried it on 86 embryos. And essentially, it worked but not really very well. Some of the embryos didn't survive. They did edit some of the DNA in some of the embryos. But even there, it also created mutations elsewhere in the DNA that they didn't intend to create. So basically, it didn't work very well.
INSKEEP: So, Rob Stein, as I'm listening to this, I'm thinking of the very strong reaction many people have to genetically modified plants - GMOs - eating them, using them in any way. There must be a very strong reaction to the idea of genetically modified people.
STEIN: Oh, yeah, absolutely. I mean, this is something that people have been worried about for generations, for decades. And, you know, there's been lots of thought and debate about doing this sort of thing. And in fact, there've been rumors that this might've happened for several weeks now. So several weeks ago, several prominent groups of scientists issued basically public appeals to the scientific community worldwide not to do this. They said, look, we're nowhere close to being ready to try this. It's not safe. We don't know if it's going to work. And that included even the researcher who developed this technique I mentioned, CRISPR. She's concerned about moving ahead too quickly.
But there's no way to really enforce that kind of moratorium. And this report essentially confirms their worst fears. So I've been in touch with some of those scientists over the last 12 hours or so. And they're basically saying, look, you know, this is exactly what we've been worried about. And this is just - it gives us another reason why we should stop doing this kind of research until we've really debated these issues a lot more thoroughly and know that this is safe.
INSKEEP: Not the end of the story. Rob Stein, thanks very much.
STEIN: Oh, sure. Nice to be here.
INSKEEP: That's NPR's Rob Stein. Transcript provided by NPR, Copyright NPR.