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expert reaction to study generating a synthetic mouse embryo model from stem cells

A study published in Cell looks at the generation of synthetic mouse embryos ex utero from mouse naïve embryonic stem cells (ESCs).


Prof Alfonso Martinez Arias, ICREA Senior Research Professor, Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), said:

“The press release is an accurate reflection of the science. This is excellent work which has been well documented and backed up with the statistical analysis. This is potentially a significant development but this is only the start of this work and before this method can change the way we carry out scientific research, it must be improved in terms of the numbers and the reliability of the morphology. This will take time but it will be done.

“Importantly, it opens the door to similar studies with human cells, though there are many regulatory hoops to get through first and, from the point of view of the experiments, human systems lag behind mouse systems.

“There are some limitations which the authors are clear on, in particular the efficiency of the process. Once these are overcome, there is real potential that this could allow for a reduction in the numbers of animal used in research.”


Dr James Briscoe, Principal Group Leader – Assistant Research Director, Francis Crick Institute, said:

“This is a valuable proof of concept demonstration that a mouse embryo-like structure can be assembled from stem cells. It builds on previous advances in developmental biology that identified the molecular recipes for producing the set of stem cells necessary for initiating embryo formation. By combining these cells together, the new study shows that it is possible to coax the development of something that resembles a mouse embryo at a stage when the main organs of the body are beginning to be established, including the nervous system, heart and gut. It is striking however, that the formation of these “synthetic embryos” was very inefficient: less than 1 in 100 attempts formed anything that looked like an embryo. Moreover, even the successful synthetic embryos appeared to be more disorderly than natural embryos. This emphasises how much we still have to learn about how embryos build themselves and the technique reported in this study is a promising approach to provide new insights into how mammalian embryos organise and construct organs. Nevertheless, the study has broad implications as although the prospect of synthetic human embryos is still distant, it will be crucial to engage in wider discussions about the legal and ethical implications of such research.”



‘Post-Gastrulation Synthetic Embryos Generated Ex Utero from Mouse Naïve ESCs’ by Shadi Tarazi et al. was published in Cell on Monday 1 August.



Declared interests

Prof Alfonso Martinez Arias: None

Dr James Briscoe: “I have no conflicts of interest”

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