It’s not often that the public can watch a scientific race virtually live. After the developmental biologist Magdalena Zernicka-Goetz from the University of Cambridge said during a lecture in Boston last Wednesday that her team had created synthetic Human Embryos from stem cells, first reported the British Guardians about it – Specialist articles had not yet been published at this time. On Thursday invited the competing Working group around the stem cell researcher Yaqub Hanna from the Weizmann Institute in Israel an article in the online database for biomedical advance publications BiorXiv, in which she presented a very similar result to Zernicka-Goetz, only with a different approach. Two further Working groups also published preliminary reports on work with artificial human embryos there on Thursday. And finally, on Friday, the team led by Zernicka-Goetz published an essay in which the researchers presented details of the lecture in Boston.

None of these articles have been reviewed in detail by independent experts. However, experts agree that this is an expected but nevertheless major step for the research field. So far, such experiments have only been described in connection with animal embryos. The competition is not only about scientific fame, but also about intellectual property rights for the methods. Researchers in the groups led by Zernicka-Goetz and Hanna stated that they were involved in patent applications.

A whole person has not yet been able to grow from the cell clusters

The embryos created from stem cells in the laboratory have to be thought of as piles of cells. They may have the potential to grow into a human, but there are no techniques for that in the lab. And you couldn’t transfer these constructs into a woman’s uterus either, because they omit a necessary development step.

The researchers therefore also refer to their synthetic embryos as “models” – possibly helpful for regenerative medicine, reproductive medicine and developmental biology. “In addition, the discussion about this type of embryo production will also pose a new challenge to the legal and ethical framework in Germany and beyond,” write Nils Hoppe and Sara Röttger from the Center for Ethics and Law in the Life Sciences (CELLS) at the Gottfried Wilhelm Leibniz Universität Hannover in a joint statement on the reports from England and Israel. “Are synthetic embryos less worthy of protection than, for example, surplus embryos from fertility treatment? We will have to reorient ourselves socially.”

Zernicka-Goetz’s team genetically modified human stem cells in such a way that they began to develop not just individual tissue types, but a complete embryo. Instead of genetic engineering, Hanna’s group used a cocktail of biochemicals to trigger this transformation. That it should be possible to grow whole embryos with different cell types from single stem cells, was previously in experiments on monkeys and mice have been shown. In this respect, the transfer to human cells was only a matter of time.

It is impressive to see “how more than a decade of very fundamental research” led to this result, says Jesse Veenvliet, head of the Stembryogenesis working group at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, who was not involved in the work . He describes the resemblance of the artificial embryos to the natural equivalents as “remarkable, almost uncanny.”

Do the experiments mark a renaissance in cloning?

Michele Boiani, head of the “Mouse Embryology” working group at the Max Planck Institute for Molecular Biomedicine in Münster, is also impressed by the work, “I am, however, critical of the linguistic nomenclature used, in which the created embryonic structures are treated as mere ‘models’ of the human embryonic development.” As a mouse biologist, he sees things this way: If the function of development is given, the constructs should simply be regarded as embryos – regardless of their biological origin. “Insofar as these recapitulate early human development, they should be called embryos and not treated as mere models – especially in the legal sense.”

Ingrid Metzler agrees, she works in the Department of Biomedical Ethics and Health Sciences at the Karl Landsteiner Private University for Health Sciences in Krems. The groups around Hanna and Zernicka-Goetz “seem to suggest that working with stem cell-induced embryo models could be an ethical alternative to research on embryos,” says Metzler. “From the group’s point of view, this is an understandable position. But I think it would be hasty to make this position a generally valid classification with research on and with these novel objects.”

From Michele Boiani’s point of view, the cell clusters created are not only embryos, but also clones that are grown from the stem cells in the laboratory. Accordingly, the experiments “ultimately represent a renaissance of cloning human embryos”.

With material from the Science Media Center