AUDIE CORNISH, HOST:
A new generation of experiments involving human embryos is raising new ethical issues. Today on MORNING EDITION, NPR health correspondent Rob Stein visited a lab where scientists discovered how to keep embryos alive in a dish longer than ever before - a development that sparked an international debate about how long scientists should be permitted to experiment on human embryos. Now, these scientists are also creating embryoids - living entities that resemble human embryos. As Rob reports now, these experiments raise their own thorny questions.
ROB STEIN, BYLINE: To see these experiments, I traveled to midtown Manhattan and made my way to a high-rise research lab at the Rockefeller University.
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ALI BRIVANLOU: Welcome, welcome. May I offer you some tea, coffee.
STEIN: I'm good. I'm good. Thank you very much. Though.
Where I met Ali Brivanlou. He studies embryos.
BRIVANLOU: Now we're going to the lab. I'm going to do a show-and-tell for you.
STEIN: Great.
The lab overlooking the East River is bright and open, and that's no accident.
BRIVANLOU: That's the make sure that there is nothing that happens in some dark rooms that give people some weird ideas.
STEIN: Brivanlou is trying to do something that might sound pretty weird. He's trying to grow things in lab dishes that look and act like human embryos. But he's not starting by fertilizing eggs with sperm the old fashioned way. He's doing it with human embryonic stem cells.
BRIVANLOU: We take the cells. We put them on this petri dish. They attach to it, and they start self-organizing and make embryonic-like structures.
STEIN: Structures that can create the three major types of cells needed to make everything in the human body. But Brivanlou's only been able to go so far using flat lab dishes, so now he and his colleague Mijo Simunovic are putting stem cells into a gel to let these embryoids grow in three dimensions.
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MIJO SIMONOVIC: And these are essentially three-dimensional structures that are mimicking developing an entire embryo.
STEIN: He shows me under a microscope.
SIMUNOVIC: So let me just find a nice one. All right. Maybe something like this?
STEIN: It looks like some sort of a silvery...
SIMUNOVIC: Exactly.
STEIN: ...Background, and there's, like, kind of gray and bright white blobs all over the place.
SIMUNOVIC: Yeah. That's it. That's - basically, you're looking at human embryonic stem cells in three dimensions. So they grow spontaneously to form a ball of cells with a cavity in its center.
STEIN: Just like an early human embryo would do in the womb. Now, these are nowhere near being fully formed embryos, but the scientists are trying to get as close as they can.
SIMUNOVIC: Essentially, we're trying to, in a way, recreate a human embryo in a dish, starting from stem cells.
STEIN: Why? To study them and hopefully make big discoveries about basic human biology and development - discoveries that could lead to new ways to prevent miscarriages, treat infertility, avoid birth defects and, Brivanlou says, maybe even unlock the mysteries of aging.
BRIVANLOU: What is the clock in the human embryo that says, OK, now you have to do this, now you have to do this? There's a tempo. It's like music. And understanding of the molecular basis of this tempo would also open up the doors to understanding aging.
STEIN: I start to wonder, though - how far could these embryoids go? Could they become an embryo?
SIMUNOVIC: Well, probably not, but they could become something that looks very much like an embryo.
STEIN: But how much like an embryo could they become?
SIMUNOVIC: That's a very good question, and we'll see. At the moment, we don't know. This is something that's very hard right now for us to understand.
STEIN: Because these embryoids could let them sidestep something called the 14-day rule. It prohibits scientists from keeping human embryos alive in the lab for more than 14 days. Two weeks is when human embryos usually start to show something called the primitive streak. It's the beginning of the central nervous system. It's also when embryos can't split into twins anymore, so some say that's when they become unique individuals. But Simunovic says these embryoids aren't subject to the 14-day rule.
SIMUNOVIC: We are not technically or ethically limited to studying these cells and studying these structures.
STEIN: You're not.
SIMUNOVIC: We're not.
STEIN: But there's a big debate about that. In some other embryoids, Brivanlou says the scientists have been surprised to see the early signs of the primitive streak.
BRIVANLOU: We started - I think we just started seeing the beginning of the early primitive streak.
STEIN: So doesn't that raise questions about the 14-day rule potentially?
BRIVANLOU: Sure. I mean, it should. If people want to discuss this as part of the 14 rule, why not?
STEIN: And they are. Insoo Hyung is a bioethicist at Case Western Reserve University.
INSOO HYUNG: These are cells that are behaving, interacting with one another and doing what embryos do in the womb. It's almost like this an inner budding life in this model that you created in the dish. That's what's was remarkable. Are we recreating a life that in the right circumstances, if you were to transfer this to the womb, it would continue its journey? So at what point is your model of the embryo basically an embryo?
STEIN: And Hyung is not alone in his concerns. George Daley is the dean of the Harvard Medical School and a leading stem cell researcher. He says scientists have been preparing for the day when stem cell research might raise these kinds of difficult questions.
GEORGE DALEY: You know, I think what prospects people are concerned about are the kinds of dystopian worlds that were written about by Aldous Huxley in "Brave New World," you know, where human reproduction is done on a highly mechanized scale in a petri dish.
STEIN: Now, Daley stresses scientists are nowhere near making that sort of thing possible and may never get there. But science moves quickly these days, so Daley says it's important to make sure all these experiments undergo intense ethical review. Brivanlou doubts his embryoids would ever actually become real embryos, but, he says, all of his work goes through many layers of careful vetting. And he's moving cautiously in the hopes of answering some big questions.
BRIVANLOU: I think science and philosophy are trying, to a large extent, to answer the most basic questions, which are - Where are we from? Where are we going? So if I can provide a glimpse of where we come from, what happened to us for us to get here - I think that, to me, is a strong enough rationale to continue pushing this.
STEIN: Rob Stein, NPR News, New York. Transcript provided by NPR, Copyright NPR.
