“They are not human embryos,” Magdalena Zernicka-Goetz told CNN. Then she described what her team had built: models of early human development, grown from stem cells with no egg and no sperm.
The work was presented this week at the International Society for Stem Cell Research’s annual meeting in Boston. It was a joint project of the University of Cambridge and the California Institute of Technology. Zernicka-Goetz, a fellow at Cambridge and a professor at Caltech, called the result “beautiful” and said it was “created entirely from embryonic stem cells.”
What the structures are
According to the Daily Mail, the structures resemble embryos in the earliest stages of human development. They have no beginnings of a brain or a beating heart. They do contain cells that would go on to form the placenta and yolk sac.
The New York Post reported that the models also include primordial cells that could eventually develop into egg and sperm cells. Zernicka-Goetz said it is the first human embryo model to specify amnion and germ cells, the precursors of egg and sperm. Nobody knows whether such structures could grow into a viable organism, or what that organism would be like.
Why researchers want them
Scientists have been bound by the 14-day rule, which caps how long an embryo can be kept developing in a laboratory. Afterward, researchers have had to wait and study later stages through pregnancy scans and embryos donated to research. The stretch between day 14 and about day 28 was the main motivation for the project.
Robin Lovell-Badge, who heads stem cell biology and developmental genetics at the Francis Crick Institute in London, told BBC Radio 4 that donated embryos are “quite rare and hard to get.” Stem cell models, he said, could yield “a lot of information” about early development without embryos made by fertilization. Scientists believe the finding could help research into rare genetic disorders and into the biological causes of miscarriage.
Zernicka-Goetz called the models “a very important path towards discovery of why so many pregnancies fail.”
Legal gap
The catch is that the law has not caught up. The Daily Mail said the synthetic embryos fall outside UK law and the laws of most countries. Implanting one in a woman’s womb would be illegal, and there is no near-term prospect of medical use. Similar work with animal embryos has been done, but those failed to develop after implantation in female animals.
Lovell-Badge raised the concern directly. “If the whole intention is that these models are very much like normal embryos, then in a way they should be treated the same,” he said. “Currently in legislation, they’re not. People are worried about this.” At a minimum, the New York Post noted, voluntary guidelines may be needed.
Sources
- Human embryos created without egg or sperm in controversial breakthrough
- Synthetic human embryos are made in scientific breakthrough
