Scientists Just Created Synthetic Human Embryos To Improve Embryonic Research

Published June 15, 2023

Researchers believe the synthetic embryos could open up new gateways into embryonic research, but others have raised ethical questions about whether these synthetic embryos could eventually develop into humans.

Synthetic Embryos From Stem Cells

CanvaSo far, it is unclear whether the embryos could develop into humans.

For the first time ever, scientists have used stem cells to create synthetic human embryos — without involving the use of eggs or sperm. Researchers believe these model embryos can provide crucial insight into the impact of genetic disorders and the biological causes of recurrent miscarriage.

Of course, the creation of these synthetic embryos has also sparked serious ethical and legal debate. As it currently stands, the use of lab-grown embryos falls outside of most countries’ legislation, including the U.K. and the United States.

As The Guardian reported, Professor Magdalena Żernicka-Goetz of the University of Cambridge and the California Institute of Technology addressed the research and the surrounding concerns at the annual meeting of the International Society for Stem Cell Research in Boston.

“We can create human embryo-like models by the reprogramming of [embryonic stem] cells,” she said. She went on to explain that while these lab-grown embryos lack a beating heart and the beginnings of a brain, they do have the makings to eventually form the placenta, yolk sac, and of course the embryo itself. However, there are no near-term prospects of using these embryos clinically.

Legally, scientists would not be able to implant one of these lab-grown embryos into a patient’s womb, and furthermore, researchers are unsure whether they even have the potential to keep maturing past the early stages of development.

In any case, the point of this research is not to artificially develop humans in laboratories, but rather to give scientists further insight into the “black box” stage of development. Essentially, researchers are legally only allowed to cultivate embryos in a lab up to a limit of 14 days, and any further observations made of the developing embryo occur further down the line via pregnancy scans or embryos donated for research.

“The idea is that if you really model normal human embryonic development using stem cells, you can gain an awful lot of information about how we begin development, what can go wrong, without having to use early embryos for research,” said Robin Lovell-Badge, the head of stem cell biology and developmental genetics at the Francis Crick Institute in London.

Still, certain experts are concerned about the ethical implications of this research, which is yet to be peer-reviewed. Several expert reactions were reported via the Australian Science Media Centre.

“The development of a human-like embryo from human embryonic stem cells raises many ethical questions in addition to any questions regarding their status under the law,” said Kathryn MacKay, a senior lecturer at Sydney Health Ethics in the University of Sydney.

“Further,” MacKay added, “there is a moral issue involved in creating something for research that may or may not have the potential to live as its own full entity. If they could live as their own full entities, then we must ask whether it is morally permissible to create living beings purely for research purposes.”

While the full details of the work have yet to be published in a journal paper, Żernicka-Goetz described to the members of the conference that she and her team have successfully cultivated embryos to a stage just beyond the equivalent of 14 days of development for a natural embryo.

Each of the model structures, grown from a single embryonic stem cell, reached the early stages of gastrulation, a developmental milestone in which the embryo forms distinct cell lines and establishes the body’s basic axes. The embryos have not yet developed beating hearts or brains, but the models did contain primordial cells that could one day turn into the cells of egg and sperm.

Previous experiments on the stem cells of mice conducted by Żernicka-Goetz’s team and another group in Israel showed that the cells could be encouraged to self-assemble into similar embryo-like models.

In these experiments, the synthetic mice embryos also formed an intestinal tract and the beginnings of a brain and beating heart. This is, in part, why experts are showing concern that human embryo models could likewise form these life-essential organs — a development that would have major ethical implications.

However, when the synthetic mouse embryos were transplanted into the wombs of female mice, they did not develop into live animals.

A similar study in China involving synthetic monkey embryos implanted in the wombs of monkeys actually resulted in some of the monkeys showing initial signs of pregnancy, though none continued to develop beyond a few days. Scientists are still trying to determine if this is due to a technical or biological cause.

The speed of progress in this field also vastly outpaces the law, meaning that, as of now, it is up to scientists to create voluntary guidelines for research on synthetic embryos.

“The successful creation of human embryo-like models holds promise for research into genetic disorders and overcomes one of the major obstacles in early life studies,” said Dr. Evie Kendal, a senior lecturer in Health Promotion at Swinburne University of Technology. “However, it also highlights the need for ethical guidance when dealing with entities that have not previously existed and are not covered by existing ethico-legal systems.”


After learning about this groundbreaking new study, read about how scientists created synthetic life from E. Coli bacteria. Then, learn about the dinosaur embryos observed in 200-million-year-old eggs.

Austin Harvey
A staff writer for All That's Interesting, Austin Harvey has also had work published with Discover Magazine, Giddy, and Lucid covering topics on mental health, sexual health, history, and sociology. He holds a Bachelor's degree from Point Park University.
Maggie Donahue
Maggie Donahue is an assistant editor at All That's Interesting. She has a Master's degree in journalism from Columbia University and a Bachelor's degree in creative writing and film studies from Johns Hopkins University. Before landing at ATI, she covered arts and culture at The A.V. Club and Colorado Public Radio and also wrote for Longreads. She is interested in stories about scientific discoveries, pop culture, the weird corners of history, unexplained phenomena, nature, and the outdoors.