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Swedish Scientist Starts DNA Experiments On Healthy Human Embryos


We are about to meet a man who is trying to modify DNA in healthy human embryos. This is something that has never been done before. The plan is to find new ways to treat infertility and to use stem cells to cure diseases. But it also raises fears about creating genetically modified human beings. NPR health correspondent Rob Stein broke the news of these experiments and brings us this exclusive story.

ROB STEIN, BYLINE: To meet the scientists doing these controversial experiments, I flew to Sweden and took the express train to Stockholm...

UNIDENTIFIED MAN: In just a few minutes, we will be arriving...

STEIN: ...And made my way to the Karolinska Institute...


STEIN: Hi, Rob Stein from NPR.

LANNER: I'm Fredrik, hey.

STEIN: ...To meet Fredrik Lanner. He's a developmental biologist conducting these experiments.

LANNER: So we'll head up to our research labs. They're upstairs.

STEIN: Lanner takes me to a storage room and shows me a row of big gray tanks.

LANNER: Our embryo samples are stored in these big thermoses.

STEIN: These are embryos created by couples who went through IVF in a clinic downstairs to try to have a baby. They're done trying, so they donated the embryos for research.

These are healthy human embryos.

LANNER: Yeah, as far as we know, they are healthy human embryos.

STEIN: But right now they're in sort of a state of suspended animation I guess.

LANNER: Yeah, yeah, exactly.

STEIN: Lanner's student twists open a valve on a gigantic silver tank, and suddenly we're engulfed in a huge white cloud. He's filling a white bucket with liquid nitrogen so they can move five of the frozen embryos to their lab. Lanner is using these embryos to try to do something that's never been done before - genetically modify healthy human embryos. He's trying to identify genetic defects that cause infertility and miscarriages.

But tinkering with the genes in human embryos has always been considered taboo because of fears it could lead to a brave new world of genetic super babies and even some kind of genetic super race. We'll get into all that later. But first, Lanner shows me what he's doing. As we enter the embryo lab, we have to pull on rubber gloves, hairnets and sterile gowns. Lanner and his student pull out a long thin plastic rod containing the embryos and begin the careful process of slowly thawing them out.

LANNER: So this, of course, as you can understand, extremely sort of high-precision work. So you need to be stable on your fingers and hands. You don't want to be dropping the embryos while you're taking them out like this.

STEIN: After several hours of work and waiting, all five embryos are finally thawed out. It turns out one didn't survive. But Lanner's ready to start editing the remaining four embryo's DNA. They take the first embryo out of an incubator and carefully move it to a dish under a microscope. I can see everything they're doing on a big monitor.

LANNER: So we will most probably soon see the embryo on the - yeah, here, you can see the embryo coming into view on the monitor. And...

STEIN: So that's a human embryo.

LANNER: So this is a human embryo. We can see there's four cells.

STEIN: It looks like a translucent gray bubble with four smaller overlapping bubbles inside. Lanner's student gently grabs the embryo with the tip of a tiny glass rod called a pipette.

LANNER: So it's now clamping on to the - sort of the egg shell with the holding pipette. So by having a negative pressure there, you can hold on to the embryo. And then the he will align the injection needle.

STEIN: The injection needle is a thin glass tube pointing at the other side of the embryo. It's loaded with a brand new kind of genetic editing tool that's revolutionizing genetic engineering. It's like a spell check for rewriting genes.

LANNER: This actually opens the door to start to look at this for the first time because we could not do this at all previously in the human embryo. It's really exciting.

STEIN: For now, Lanner's just trying to knock out different genes to see what they do. But the goal is to eventually use this to fix genetic defects.

LANNER: So now he's going into the cell. We see the needle is inside the cell and then dispensed and moved out. I don't know if you caught that, but you could see a slight sort of movement at the needle when it dispensed. So we could even by eye - or through the microscope see that there's a sort of shift.

STEIN: Wow, wow - so that's how you edit the DNA in a human embryo.

LANNER: Yeah, yeah.

STEIN: Lanner hopes editing genes in embryos like this will help millions of women who have trouble having babies.

LANNER: Having children is one of the major drives for a lot of people. And people who don't have problems with getting kids may not understand about - for people that do struggle with this, it can tend to become an extremely important part of your life.

STEIN: Beyond infertility, Lanner also hopes what he learns will help scientists turn embryonic stem cells into all kinds of new treatments.

LANNER: If we can understand how these early cells are regulated in the actual embryo, this knowledge will help us to treat patients with diabetes or Parkinson's or different types of blindness. That's another exciting area of research as well.

STEIN: But Lanner's experiments are hugely controversial. Some people have moral objections to doing any kind of research on human embryos. But editing the DNA in embryos is even freaking out people who think that's OK.

MARCY DARNOVSKY: The production of genetically modified human embryos is actually quite dangerous.

STEIN: Marcy Darnovsky heads a genetic watchdog group called the Center for Genetics and Society.

DARNOVSKY: It's a step toward attempts to produce genetically modified human beings. This would be reason for the already grave concern.

STEIN: One fear is that scientists could make some kind of mistake and spawn new mutations that would be passed down for generations.

DARNOVSKY: When you're editing the genes of human embryos, that means you're changing the genes of every cell in the bodies of every offspring, every future generation of that human being. So these are permanent and probably irreversible changes that we just don't know what they would mean.

STEIN: But even if it's safe, Darnovsky and others still worry about what designer babies would do to society.

DARNOVSKY: If we're going to be producing genetically modified babies, we are all too likely to find ourselves in a world where those babies are perceived to be biologically superior. And then we're in a world of genetic haves and have-nots. That could lead to all sorts of social disasters. It's not a world I want to live in.

STEIN: Lanner says he has no interest in ever doing anything like that. In fact, at the moment, that sort of thing is banned in Sweden. And, Lanner says, who knows if it would ever be safe to use a genetically modified embryo to make a baby.

LANNER: It's not the technology that should be taken lightly. So I really of course stand against any sort of thought that one should use this to design designer babies or enhance or sort of - aesthetic purposes and so on. But banning everything without knowing if this could be useful technology - I think it's wise to be allowed to do fundamental research so we can gain more information about this technology and potentially use it in the future.

STEIN: During my visit, Lanner tried to edit the DNA in four embryos. Just as I was leaving, Lanner checked them one last time before placing them back into an incubator.

LANNER: OK, so one cell has already divided here. So now this embryo has five cells. So it's undergone cell division in this last half hour or so while it's been sitting there.

STEIN: Wow, so it's developing right in front of us here.

LANNER: Yeah, yeah. I'm happy that we got these three injected embryos and it'll be really exciting to see how they develop over the weekend.

STEIN: The fourth embryo got damaged in the process, but Lanner's planning to do this over and over again until he gets good at editing the DNA in human embryos. Scientists in Britain are planning to start similar experiments later this year. Rob Stein, NPR News, Stockholm. Transcript provided by NPR, Copyright NPR.

Rob Stein is a correspondent and senior editor on NPR's science desk.
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