Synthetic Embryos

An Unsettling New Development in Developmental Biology

A paper currently under peer review claims that researchers have made a breakthrough in synthetic human embryos.

The creation of life in a lab is an old trope of science-fiction, but all attempts to create life from non-life have been abysmal failures. It seems to be one of the best-attested laws of nature: Life does not come from non-life. Scientists are no closer now to assembling a single functional cell in the lab than they were in the Middle Ages.

However, creating life from life is a different matter. Living matter has a remarkable capacity to change form and grow, almost as if it had a mind of its own—almost as if it were, well, alive. Embryonic stem cells in particular are “pluripotent”—they seem to be able to turn into just about anything with the right trigger. That’s how a full human with many different types of tissue can arise from a single cell.

Developmental biologists have been trying for some time now to make stem cells replicate and differentiate outside the womb, just as they do inside the womb. It’s not easy, because they are designed to develop in a certain environment. But recently, a group of researchers were able to “unleash the self-organizing capacity of mouse stem cells” to create synthetic mouse embryos ex utero (i.e. outside the uterus).

The authors of the new paper reproduced this method using human stem cells, to good result. They were able to make stem cells replicate and self-assemble into what were essentially model human embryos, outside the womb. They were not real embryos, exactly; because they did not perfectly develop as embryos do, they would not have been able to survive and continue to develop into human children. But they did develop some of the main structures of a 14-day-old embryo, as well as the structures that form around the embryo in the womb, such as a yolk-sack. Essentially, the researchers created a synthetic approximation of a 14-day-old embryo, but without an egg ever being fertilized by a sperm cell, and without the body of a mother involved.

An Alternative to Killing People?

The authors indicate that this innovation will be used to study embryonic development in a more accessible environment, without the ethical and technical problems of having to constantly take embryos from the wombs of human mothers to dissect. And indeed, the good side of this study is that it seems as if the scientific community is responding to legal pressure to move away from the practice of dissecting and experimenting on human embryos.

A similar hopeful innovation was the discovery of a technique to trigger something in a human skin cell that makes it revert to a stem cell—meaning that stem cells no longer have to be sourced from human brains; they can be taken from human skin instead. These innovations show that if scientists are legally barred from ethically problematic (i.e., potentially evil) practices, they will often find a way to continue the research without committing those acts. This runs against the narrative that says we just have to do these things in the name of progress. Progress can often find a way around barriers. We don’t necessarily have to kill babies in order to advance as a civilization.

That being said, there is an unsettling question floating around this new research: at what point is a “synthetic” embryo also a baby? We should of course be skeptical of the idea that something artificial could ever be a living person with a soul—but is such an embryo really “artificial” in any deep sense, if he or she was grown from a living human cell?

Are “Synthetic” People … People?

Fortunately, some people in the scientific community are concerned about this. In an MIT Technology Review piece on the new paper, science writer Antonio Regalado quotes an anonymous journal editor:

We need a defined framework, but instead what we see here is a fairly wild race between labs. The overarching question is: How far do they go, and where do we place them in a legal-moral spectrum? How can we endorse working with these models when they are much further along than we were two years ago?

Most scientists don’t seem to think that these lab-made model embryos are real embryos, yet. But where is the line? If scientists can make stem cells begin to take the shape of a human embryo—what if they could make them complete the job? What if they could make a synthetic embryo that was not merely an approximation or “model” of an embryo, and how would you decide when that had happened?

Of course, at the moment there is no artificial womb that can keep a developing child alive to full gestation. But there are researchers working on that problem, too. Antonio Regalado questioned a developmental biologist, Carlos Gantner, on that point. “You’re digging a tunnel to meet in the middle, and I see no reason why that would stop,” he replied. “There is no reason you couldn’t reproduce this way.”

In other words, we are one step closer to being able to grow babies in bottles, like the World Controllers in Aldous Huxley’s Brave New World.

Like most scientific developments, this one could be taken in many directions, some worse than others. We’ll see where it ends.

Further Reading

• Katie Breckenridge, “IVF: The Devil in the Details”
• Denyse O’Leary, “Cell Division”
• Daniel Witt, “Dr. Frankenstein's Students”
• Daniel Witt, “The Age of Cyborgs”
• Joe Allen, "What’s It Like To Be A Blob Of Brain?"