RACHEL MARTIN, HOST:
And now a major development in the world of science. For the first time, doctors have used a revolutionary gene-editing technique to try to treat a patient by editing their DNA while it is still inside their body. NPR health correspondent Rob Stein is one of the reporters following this story, and he joins us this morning. Hi, Rob.
ROB STEIN, BYLINE: Good morning, Rachel.
MARTIN: So scientists edited someone's DNA from inside their body, Rob?
MARTIN: Explain (laughter). How does that work? What does that mean?
STEIN: Yeah. So they've literally genetically modified someone from inside using a powerful new way to edit DNA called CRISPR. You know, and before this, scientists trying to use CRISPR to treat diseases had been taking cells out of patients' bodies, editing the DNA in the lab and then infusing the genetically modified cells back in.
STEIN: But now, for the first time, doctors didn't take any cells out of the patient. They figured out how to get this microscopic gene-editing tool inside the body to basically do a kind of genetic surgery on cells while the cells and the DNA is still inside the body - so to genetically modify someone from within.
MARTIN: That's amazing. How did this begin? I mean, how did we get to this point?
STEIN: They tried this first on someone with a rare, but terrible genetic disease that destroys key cells in the retina in the eye. So many people born with this are essentially blind. They can only maybe tell the difference between light and dark and maybe detect motion.
MARTIN: Wow. And so can you explain in layman's terms, as best you are able, the process of trying to fix this?
STEIN: Yeah, yeah. It's actually really fascinating. So a surgeon cut a tiny hole in the patient's eye, then dripped three little drops of liquid under the retina. Those drops had billions of a harmless virus that had been genetically engineered to carry the genetic coding for making the CRISPR gene-editing surgeon inside the retina, inside the cells.
STEIN: The CRISPR then, hopefully, literally cut out the genetic code causing the disease, letting the cells make a crucial protein that will hopefully heal the sick cells in the retina, giving the patient the ability to see. Here's Eric Pierce. He's a Harvard doctor running the study.
ERIC PIERCE: If we can fix the underlying genetic defect, we have the potential to restore vision to people who never had normal vision before. It would, indeed, be amazing.
MARTIN: I mean, the potential to restore vision - I imagine that there would be potential to address other ailments, other diseases, right?
STEIN: Yeah, that's right. That's right, you know? So that's why scientists are so excited about this. There are many other diseases that, you know, can't really be treated by taking cells out a patient's body and editing them and putting them back in - you know, brain diseases like Huntington's disease, maybe some inherited forms of dementia, muscle diseases like muscular dystrophy. So the hope is that this could be the beginning of a whole new era of medicine, which scientists take, you know - edit people's genes while the DNA's still inside their body to treat their diseases.
I talked to Francis Collins about this. He leads the National Institutes of Health.
FRANCIS COLLINS: All of us dream of what time might be coming where we could apply this approach for thousands of diseases. This is the first time that's being tried in a human being. And it gives us hope that we could extend that to lots of other diseases if this works and if it's safe. This is a significant moment.
MARTIN: Amazing. So what does happen right now?
STEIN: Yeah. So they did this procedure at the Casey Eye Institute - that's at the Oregon Health and Science University in Portland - and on the first volunteer in the study, you know, that was designed to test this. And the first thing that doctors and scientists are looking for is, you know, whether this is safe, you know?
Remember, nothing like this has ever been done before. So they're starting with a very low dose and an older patient who already can't really see very much. And they're only treating one eye. The idea here is just to make sure this doesn't backfire somehow and end up destroying whatever vision is left instead of helping. I talked to Charles Albright about this. He's from Editas Medicine, one of the companies sponsoring the study.
CHARLES ALBRIGHT: There's always a potential with any experimental medicine for things to happen that you don't anticipate. And so you always want to start in a situation where if something unexpected did happen, the chances of it causing damage is the least that you can possibly make it.
STEIN: So the scientists, you know, they're going to, hopefully, see if this patient starts to see better within weeks. But they'll be watching really closely. And if it does seem to be safe and it does seem to be working, they'll try higher doses on younger patients - even kids, who have the best chance this might actually help them the most.
MARTIN: All right. NPR health correspondent Rob Stein. Rob, thanks. We really appreciate it.
STEIN: You bet, Rachel.
(SOUNDBITE OF MARLEY CARROLL'S "STARLINGS")
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