美国国家公共电台 NPR--Scientists near a breakthrough that could revolutionize human reproduction（在线收听）

Scientists near a breakthrough that could revolutionize human reproduction

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Researchers are inching closer to mass-producing eggs and sperm in the lab from ordinary human cells. The technique could provide new ways to treat infertility but also open a Pandora's box.

STEVE INSKEEP, HOST:

We are close to a revolution in the way that human beings reproduce. Scientists are near creating human eggs and sperm in the lab with any one person's genes. What does that mean for humanity? Here's NPR health correspondent Rob Stein.

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ROB STEIN, BYLINE: It's a Wednesday morning at the National Academies of Sciences, Engineering, and Medicine in downtown Washington, D.C.

ELI ADASHI: Welcome, everybody, to the National Academy of Medicine workshop.

STEIN: Dr. Eli Adashi from Brown University opens the Academy's first gathering to explore the latest scientific developments and complicated social implications of something known as in vitro gametogenesis, or IVG, which involves making human eggs and sperm in the laboratory from any cell in a person's body.

ADASHI: It is on the precipice of materialization, and IVF will probably never be the same.

STEIN: Japanese scientists describe how they've already done this in mice, coaxing cells from the tails of adult mice to become what's known as induced pluripotent stem cells, or IPS cells, and then coaxing those cells to become mouse sperm and eggs. They've even used those sperm and eggs to make embryos and implanted the embryos into the wombs of female mice, which gave birth to apparently healthy mouse pups. Mitinori Saitou joins the workshop via Zoom from Kyoto University.

MITINORI SAITOU: We are in the process of translating these technologies into humans.

STEIN: In fact, Saitou says he's already pretty far down that pathway. He's turned human blood cells into IPS cells and then used them to create very primitive human eggs. Others have created primitive human sperm this way. They're not developed enough to make embryos or babies, but they're working on that.

SAITOU: OK. Thank you very much.

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HUGH TAYLOR: Well, good morning. Welcome to Day No. 2. Let's get started.

STEIN: Dr. Hugh Taylor from Yale University summarizes what the group's learned so far.

TAYLOR: I've been really impressed with all the data that we've seen here today and just how quickly this field is evolving. And it makes me confident that it's not a matter of if this will be available for clinical practice, but just a matter of when.

STEIN: With that, Taylor opens a discussion of how IVG could help people. Andrea Braverman studies infertility at Thomas Jefferson University in Philadelphia.

ANDREA BRAVERMAN: This obviously could be life-altering for individuals to build that family that they dream of through IVG.

STEIN: Because infertile women and men could have kids with their own DNA instead of someone else's sperm and eggs. Same goes for women of any age, rendering the biological clock irrelevant. But Braverman says that raises lots of questions.

BRAVERMAN: Yes, it's great to be able to not have to worry as a woman that 40 is the cliff we fall off of. But on the other hand, what are the implications for families, for the children that have parents that are older? I always think of freshman move-in day in your 80s.

STEIN: IVG could also let gay and trans couples have babies that are genetically related to both partners. Katherine Kraschel studies reproductive health issues at Yale.

KATHERINE KRASCHEL: We too could point to our children and say, he has your eyes and my nose in a way that is something that I think many queer people covet.

STEIN: But Kraschel worries that could undermine acceptance of gay people parenting children who aren't genetically related to them through adoption or by using other people's sperm and eggs.

KRASCHEL: To the extent IVG replaces markets in sperm and eggs, concerns about backsliding, I think, are really warranted.

STEIN: But that's not all. Dr. Paula Amato from the Oregon Health & Science University in Portland points out what she calls solo IVG could allow single people to have unibabies, babies with just one person's genes.

PAULA AMATO: In theory, you could reproduce with yourself, and the, you know, resulting child would be 100% related to you. You could do that if you wanted to.

STEIN: At the same time, the DNA for IVG could come from anywhere a single cell could be found. Hank Greely, a bioethicist at Stanford, raises some of the provocative possibilities.

HANK GREELY: Ninety-year-old genetic mothers, 9-year-old genetic mothers, 6-month-old fetuses that become genetic parents, people who have been dead for three years whose cells were saved to become parents.

STEIN: People could even potentially steal the DNA from celebrities from, say, a clipping of their hair to make babies.

GREELY: One law we definitely need is to make sure people can't become genetic parents without their knowledge or consent.

STEIN: Throughout the meeting, researchers and bioethicists warn that the ability to create a limitless supply of IVG embryos combined with new gene-editing techniques could turbocharge the power to eradicate unwanted genes. That could eradicate genetic diseases but also move designer babies even closer to reality. Amrita Pande is a professor of sociology at the University of Cape Town in South Africa.

AMRITA PANDE: The desire to genetically modify the future generation in a hunt for an assumed perfect race, perfect baby, perfect future generation is not science fiction. IVG when used with gene-editing tools like CRISPR should make us all worried.

STEIN: Worried about drives to weed out unwanted traits like blindness and deafness. Now, everyone agrees that IVG is probably years away and may never happen. There are still huge technical hurdles and questions about whether this could ever be done safely. But Dr. Peter Marks, a top official at the Food and Drug Administration, tells the group the agency is already exploring the implications of IVG.

PETER MARKS: It's an important technology that we are very interested in helping move it forward.

STEIN: But, Marks notes, Congress currently prohibits the FDA from even considering any proposals that would involve genetically manipulated human embryos.

MARKS: This creeps out our attorneys, OK? It makes them feel uncomfortable in this space.

STEIN: But if IVG remains off limits in the U.S., Marks and others warn IVG clinics could easily spring up in other countries with looser regulations, creating a new form of medical tourism that raises even more ethical worries.

Rob Stein, NPR News, Washington.

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INSKEEP: Wow, that's just the beginning of that topic. And Rob will bring us more on the implications of IVG in future reports.

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