The scientists have created synthetic human embryos using stem cells, in a pioneering advance that avoids the need for eggs or sperm. This was reported on Wednesday in scoop by the British newspaper The Guardian.
Magdalena Zernicka-Goetz, professor at the University of Cambridge and the California Institute of Technology and leader of the responsible scientific team, described her work that same day at the annual meeting of the International Society for Stem Cell Research in Boston (USA).
These model embryos, similar to those found in the early stages of human development, could provide crucial information about genetic disorders and the biological causes of recurrent miscarriages. Since otherwise it is difficult to find this knowledge.
“The regulations of many countries prohibits the study in vitro of human embryos beyond 14 days, when the embryo’s gastrulation and many organ formation processes begin”, reveals Gemma Marfany, professor of Genetics at the University of Barcelona (UB) and head of the CIBERER group.
Therefore, much of the scant knowledge that science has of this phase comes from studies in embryos of other mammals, “but not everything can be directly extrapolated,” adds Marfany. One way to solve this problem is to generate embryoids, i.e. embryo-like structures made from embryonic cell culture.
“In these sets of cells, through genetic manipulation, it is possible to achieve differentiation towards different embryonic tissues and study how it occurs and whether it recapitulates embryonic development”, he qualifies in SMC Spain the researcher.
At the time of publication of the article in Guardian the paper had not been peer-reviewed nor did it have preprint —prepublication that has not been peer reviewed.
They are not human embryos but embryo models, and they are not the only ones created recently
After the report came out, Zernicka-Goetz distanced herself from the news given by the outlet, denying on Twitter that his work dealt with synthetic human embryos and referring to these as “models”.
“Thank you very much, Helen! It is important to emphasize that these are not synthetic embryos, but embryo models and that our research is not to create life, but to save it. I hope the paper come out soon and everything is much clearer”, can be read in the tweet.
The structures created by the Zernicka-Goetz team,They don’t have a beating heart or the beginning of a brainbut include cells that would normally form the placenta, the yolk sac, and the embryo itself.
However, this does not eliminate the ethical and legal problems that this scientific field raises. For example, laboratory-grown entities fall outside current legislation in the UK and most other countries.
“Unlike human embryos from in vitro fertilization (IVF), where there is an established legal framework, At present there is no clear regulation that regulates the models of human embryos derived from stem cells.“, reports James Briscoe, group leader and deputy director of research at the Francis Crick Institute (UK).
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The more similar human embryo models derived from stem cells resemble human embryos, the more important it is have clear rules and guidelines on its use
“, he maintains in SMC
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It is not the only twist that the news gave. That same Thursday, The country anticipated that the researcher Jacob Hannah and his team had managed to generate human embryo models from stem cells without gene editing. The Spanish newspaper had agreed to the preprint before published in the bioRxiv repository.
A few hours later, Zernicka-Goetz’s team posted theirs on bioRxiv as well. The controversy was served.
“This is not serious science and it is bad journalism”, he affirms to The country Jacob Hanna himself. “According to what Professor Zernicka-Goetz presented yesterday, these structures cannot be qualified as an embryo model, because an embryo should have a placenta, yolk sac, amniotic cavity and chorionic sac, and none of these parts appear. Your data seems very unconvincing to me.”
Why Scientists Are Trying to Create Synthetic Human Embryo Models
Science cannot accurately see what happens inside the uterus at any stage of pregnancy and the regulations on 14 days prevent the study of human embryos that have passed that stage in the laboratory. The first stages of human development still keep great mysteries today.
Therefore the 2 jobs cultured embryos until a stage equivalent to 14 days of development from a natural embryo. That’s when it occurs gastrulationthe point at which the embryo goes from being a continuous sheet of cells to forming differentiated cell lines and establishing the basic axes of the body.
At this stage, “the embryo does not yet have a beating heart, intestine or early brain, but the model showed the presence of primordial cells that are the precursor cells of the ovum and spermatozoon,” Zernicka-Goetz describes in her work.
Both the Israeli and UK/US teams have reached the same stage of human development, but using different methods.
“While the one of Zernicka-Goetz does this by attaching transgenic cells for different differentiation factors, Hanna uses unmodified stem cells, mixed with others that are indeed genetically modified”, he clarifies in SMCMarfany.
The result in both cases is synthetic models of human embryos, but with nuances
“The stem cell-derived embryonic models from Hanna’s group are structurally more similar to embryos, while those from the Zernicka-Goetz group would be less structured, but gene expression in these embryoids would support that they are differentiating into precursors.” of organs”, points out the researcher.
However, as the professor recalls, there is still a lot to be investigated and the main question currently is how to categorize these models. “If they are considered human embryos or not. At the moment they are not, because they are not viable nor do they show all the potential of a human embryo”, ensures.
