MARY LOUISE KELLY, HOST:
Scientists in Japan say they have taken a crucial step towards creating human eggs in the lab that could eventually revolutionize the way people have babies. NPR health correspondent Rob Stein has the details.
ROB STEIN, BYLINE: So the first question you may have is, why in the world would scientists want to manufacture human eggs in their lab? Amanda (ph) Clark at UCLA says there's a very good reason.
AMANDER CLARK: For many years, we've been looking for a way to understand human fertility and infertility given that such a large fraction of the human population does experience difficulties getting pregnant and having a child.
STEIN: Scientists around the world have been racing to try to turn stem cells into human sperm and eggs. They were able to do it for mice and have even bred baby mouse pups with mouse eggs and sperm they made from stem cells, but they could never even get close to that for humans.
CLARK: The field has been stalled for a number of years at this bottleneck.
STEIN: But not anymore. Scientists at Kyoto University say they've broken that bottleneck. They finally figured out how to create very immature human eggs in a lab dish.
CLARK: This is incredibly exciting because for the first time, scientists have been able to convincingly demonstrate that we are able to make eggs. They're very immature eggs, but we're able to make eggs in the laboratory.
STEIN: They did it by taking human blood cells, turning them into stem cells and then coaxing the stem cells into becoming very immature eggs using little mini ovaries they created in a lab from mouse cells.
CLARK: They created a tiny, little, artificial ovary. And inside that little reconstituted ovary were these very immature human egg cells. So the entire experiment happened entirely within an incubator within a laboratory.
STEIN: Now, these egg cells are way too immature to make a baby, but that's the ultimate goal. And if it works and is safe, it could help millions of people suffering from infertility. The same thing could be done starting with human hair or skin cells. So Hank Greely, a bioethicist at Stanford, says that's just the beginning.
HANK GREELY: If we can make human eggs and sperm from skin cells, it opens up an enormous number of possibilities for changing how humans reproduce.
STEIN: For example, gay couples could make babies with sperm and eggs made from their own skin cells. And easy access to eggs means it could become routine to scan the DNA of embryos before anyone tries to have a baby.
GREELY: Doing genetic testing basically on a large chunk of every generation of babies before they even become fetuses, while they're still embryos, and having parents or perhaps governments pick and choose which embryos can go on to become babies - that has lots of implications.
STEIN: And that's not all. Babies could be made from the cells of children, grandmothers, even dead people, according to Dartmouth bioethicist Ronald Green.
RONALD GREEN: So there are some very weird possibilities emerging.
STEIN: Theoretically people could even make babies from cells stolen unwittingly from celebrities.
GREEN: A woman might want to have George Clooney's baby, and his hairdresser could start selling his hair follicles online so that we suddenly see many, many progeny of George Clooney without his consent.
STEIN: Nothing like this is possible anytime soon. A lot more research is needed to prove eggs and sperm made this way work and are safe. But this new research suggests that's where humanity might be headed. Rob Stein, NPR News.
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