Scientists Create Living Entities In The Lab That Closely Resemble Human Embryos

These structures made from living human cells are similar to human embryos at the stage when they implant in the womb. They allow scientists to research new ways to treat infertility.

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MARY LOUISE KELLY, HOST:

Scientists have created living entities in lab dishes that resemble human embryos more closely than ever before. The goal - gain insights into human early development and find new ways to prevent and treat many medical problems. But the research is raising sensitive moral and ethical concerns. NPR health correspondent Rob Stein has the story.

ROB STEIN, BYLINE: For decades, scientists have been trying to unlock the mysteries of how a single cell becomes a fully formed human being. What goes wrong to cause genetic diseases, miscarriages, infertility? But embryonic development is mostly hidden inside women's bodies during pregnancies, and it's difficult and controversial to study human embryos in the lab. Jun Wu is a molecular biologist at the University of Texas Southwest Medical Center in Dallas.

JUN WU: We know a lot about animals like mice and rats, but not a lot with human early development. (Unintelligible) black box. We really don't know much about human development.

STEIN: So scientists started coaxing human cells in lab dishes to form themselves into what looked like very primitive human embryos. These entities are called embryoids. Now, Wu and another international team of scientists have gone farther than ever before. They have created complex balls of living cells that look a lot like embryos at the stage when they usually implant in the womb to begin developing into babies. Embryos at that stage are called blastocysts, so the scientists call these blastoids (ph). Jose Polo at the Monash University in Australia leads the other team.

JOSE POLO: We are very excited, yes. We are very excited that now, with the technique, we can create hundreds of these structures. So it will allow us to scale up our understanding of very early human development. So we think that this will be very important.

STEIN: Other scientists are hailing the research. Jianping Fu is doing similar experiments at the University of Michigan.

JIANPING FU: I will consider this as a major advance in the field. This is really the first complete model of a human embryo. This is really a major advance.

STEIN: Now, these blastoids aren't quite complete enough to make a baby, and that's not what these scientists are trying to do, but they are getting pretty close.

INSOO HYUN: Which then raises a really interesting question of, at what point as an embryo model become a real embryo?

STEIN: Insoo Hyun a bioethicist at Case Western Reserve University and Harvard. He says these blastoids raise questions about how far scientists should be allowed to go. And he notes these blastoids were made from stem cells and skin cells, no need for sperm or eggs.

HYUN: This work is absolutely unnerving for many people because it really challenges our tidy categories of what life is and when life begins. This is what I call the biological metaphysical time machine.

STEIN: Now, Hyun says this research could be very valuable, so it's important to come up with clear new guidelines so scientists know what's permissible and what's off limits. But Kirstin Matthews, a bioethicist at Rice University, worries about any suggestion of easing restrictions on these kinds of experiments.

KIRSTIN MATTHEWS: Which means that we could just keep growing these sort of humans in a test tube and not even considering the fact that they're so close to being human, right? I guess I watch too much sci-fi, so I find it really disturbing.

STEIN: In fact, another team of scientists in Israel is now reporting that they've figured out how to grow mouse embryos in their lab outside of a uterus, a step toward a so-called artificial womb. Now, the researchers who created these blastoids say they have no intention of doing anything like that. They just want to study their blastoids in the lab for short periods. And current guidelines bar scientists from keeping them alive for more than 14 days. But experiments like these have stirred moves to lift that prohibition.

Rob Stein, NPR News. Transcript provided by NPR, Copyright NPR.