AILSA CHANG, HOST:
Scientists recently made headlines when they announced they had figured out how to edit DNA in human embryos for the first time. This week, the scientists invited NPR health correspondent Rob Stein into their lab in Portland, Ore., to watch them edit the genes of these human embryos. He is the first journalist to do this. And I am so glad he's in the studio right now because I cannot wait to hear more about this. Hey, Rob.
ROB STEIN, BYLINE: Oh, hey, Ailsa.
CHANG: So you got the first invite as a reporter to watch them do this. What was that like?
STEIN: Yeah, Ailsa. It was fascinating. I mean, scientists are doing things that have simply never been done before. And this is some of the coolest but also some of the most controversial research going on in the world today. And the reason is is they're making changes in human DNA that can be passed down for generations. So they...
CHANG: It's literally made hereditary.
STEIN: That's right. Every generation to come could inherit whatever changes they make in the DNA.
STEIN: And what they did is they let me watch every step of the process. They let me watch as they created embryos in their lab specifically with genetic mutations so they can then go ahead and fix the mutations and make the embryos healthy.
CHANG: Wait, so how exactly do you edit the DNA in an embryo?
STEIN: Well, it all starts with human eggs, which the researchers get from women who donate them for their experiments. And so I started my day at a big glass building at the Oregon Health and Science University...
AMY KOSKI: We're on the 13th floor.
STEIN: ...In a lab with Amy Koski. She's the lab manager. And she just got a call from a fertility clinic three floors downstairs.
KOSKI: I've been instructed from the fertility clinic that they have an egg that we're ready to go pick up. Should we just go do this thing?
STEIN: Great. Let's go.
STEIN: She grabs a metal box that looks sort of like a lunchbox and we head for the elevator.
COMPUTER-GENERATED VOICE: Going down.
KOSKI: This is our portable incubator which keeps the eggs warm while we're moving up and down the elevators.
COMPUTER-GENERATED VOICE: Tenth floor.
STEIN: We rush to the clinic. Doctors there are removing eggs from a woman going through IVF to try to have a baby.
KOSKI: You want to keep the eggs very happy and warm. And when you're jostling them or moving them, they get a little unhappy.
STEIN: When we get downstairs, a doctor in scrubs opens a big incubator to get what was collected just a few moments ago from the donor in a nearby room and gently places a dish inside Koski's portable incubator.
KOSKI: Thank you.
UNIDENTIFIED MAN: OK.
STEIN: And then we walk really slowly back to the elevators.
Does this make you nervous?
KOSKI: Every single time. By the time I get upstairs, I take a deep breath for the first time and I pause and think, oh, today, I didn't drop anything.
STEIN: Back upstairs, we head into a small, dark room.
KOSKI: And we're going to very carefully transfer from the traveling incubator into what we call our waffle makers, which are just benchtop incubators for embryos.
STEIN: Moments after the eggs are safely inside, the door opens again.
SHOUKHRAT MITALIPOV: Hello.
STEIN: Hi, how are you?
MITALIPOV: Good, thank you. Nice to meet you - Shoukhrat.
STEIN: It's Shoukhrat Mitalipov. He's a biologist born in the Soviet Union who runs the lab.
MITALIPOV: Good to have you. So this is our small room. But that's where usually lots of big science happen.
STEIN: Big science? What do you mean by that?
MITALIPOV: We believe this room is really magic in terms of science. And lots of big discoveries came in this room, particularly this microscope.
STEIN: He points to a big microscope where another scientist is positioning a petri dish. She flicks on a light that makes it glow in the dark. Everything she's doing is projected onto a computer screen.
MITALIPOV: She's loading now eggs. You see? That's a human egg.
STEIN: That's a human egg?
MITALIPOV: Yep, yep. That's a mature human egg. And you can see it's moving - so actually, two of them there. See?
STEIN: So that's two healthy human eggs?
STEIN: They look like round, shimmering, silvery blobs. Suddenly, a bunch of tiny ovals flit across the screen.
MITALIPOV: These are sperm. You see? Floating sperm - and they twitching.
STEIN: Oh, yeah. They're like - have a little tails and, like, swimming.
MITALIPOV: Yeah, yeah. So yeah, that's how we know that sperm is feeling well and it's swimming.
STEIN: But these aren't just any sperm. They're carrying a genetic mutation that causes a potentially fatal heart condition. The scientists are fertilizing the eggs to create embryos that carry this mutation to see if they can fix them. A long, thin, pointy glass rod appears on the screen.
MITALIPOV: Can you see this pipette - tiny pipette?
STEIN: A pipette is like a needle?
MITALIPOV: Yep. It's a microscopic needle.
STEIN: So she's sucking some of the sperm into the hollow glass needle, the pipette?
STEIN: Then she draws something else into the pipette with the sperm. It's a microscopic gene editing tool that lets scientists make very precise changes in DNA. It can zero in on the genetic mutation and literally cut it out, creating a healthy embryo.
MITALIPOV: And now she'll be shooting that sperm along with that DNA correction solution. And it's all done.
STEIN: That's it?
MITALIPOV: Yep (laughter).
STEIN: She just did it?
MITALIPOV: Was it simple?
STEIN: Wow. She just shot it right in there.
STEIN: Wow. That was amazingly fast.
MITALIPOV: This is how we do it (laughter).
STEIN: Mitalipov says this is how his team succeeded where others failed. They injected the mutant sperm and the DNA editor at the same time.
Basically, what we just saw you do was you fertilized an egg and did kind of DNA surgery on it all the same time.
MITALIPOV: Exactly. So this is DNA surgery.
STEIN: They're not sure exactly how it works. But they think when the defective gene is cut out, this triggers the embryo to repair itself. Mitalipov says this procedure could wipe out a long list of diseases that have plagued families for generations.
MITALIPOV: The estimate is about 10,000 different mutations causing so many different conditions and diseases.
STEIN: Like Huntington's disease, cystic fibrosis - even, possibly, inherited forms of Alzheimer's and breast cancer.
MITALIPOV: And we're talking about million of people affected.
STEIN: Now, this all may sound pretty great. But there are still lots of questions about it.
CHANG: Yeah, like what kinds of big questions?
STEIN: Well, first of all, Ailsa, there are some scientists that are still skeptical that Mitalipov has really done what he says he's done. And this is pretty common in science. Whenever anybody makes a big discovery like this, nobody's really sure until somebody else is able to do it themselves. Another concern is that some scientists may kind of rush ahead with this and try to make a baby before anyone knows for sure that it works and it's safe.
CHANG: Even if it is safe, it's still really controversial, right?
STEIN: It's incredibly controversial. I mean, scientists, they could make some kind of mistake and create new diseases that would then be passed down for generations.
STEIN: And some critics say, look, these scientists are kind of playing God. They are doing things that could change the course of human evolution, lead to scary scenario scenarios like designer babies...
STEIN: ...And genetically enhanced people. And I asked Mitalipov about this. And this is what he said.
MITALIPOV: I don't think I'm playing God. We have intelligence to understand diseases, eliminate suffering. And that's what I think is the right thing to do.
CHANG: Wow. It's just so fascinating that you were on the front lines of genetics. Thank you so much for coming in and teaching us about this.
STEIN: My pleasure.
CHANG: That's NPR health correspondent Rob Stein.