Scientists create synthetic human embryo – 06/24/2023 – Science

In a busy week in the genetics world, at least three different teams of scientists have announced the development of “synthetic” human embryo models in the laboratory. The material was cultivated through the reprogramming of stem cells, without the need to use eggs or sperm.

Two groups claim to have managed to advance with growth to what would be equivalent to the 14 days of a natural embryo, while a third reached stages similar to those seen in the fourth week post-fertilization.

The main application for this type of research is the study and understanding of diseases and other conditions during the early stages of embryonic development. Genetic problems or even recurrent spontaneous abortions could be investigated using this method.

Although the scientists emphasize that the material created now in the laboratory could not be used to generate life, the discoveries already provoke controversy regarding the ethical aspects of this type of work.

So far, however, details on the progress of the work are limited to information provided by the research authors themselves. The experiences have not yet been published in scientific journals nor have they gone through peer review, an essential step for verifying the information and checking for any inconsistencies.

The first announcement to gain worldwide attention was from the group led by Professor Magdalena Żernicka-Goetz, linked to the University of Cambridge (UK) and the California Institute of Technology (USA), during the annual meeting of the International Society for Research in Cells -Trunk, held last week in Boston, in the United States.

The model’s structures were created from embryonic stem cells, which reached the beginning of the so-called gastrulation phase, when cell differentiation begins to form the different lineages that make up the human body.

At this point of development, the embryo still does not have organs or a heartbeat, but, according to the researcher, the model already had the presence of egg and sperm precursor cells.

In an interview with the British newspaper The Guardian, Żernicka-Goetz said that the feat is unprecedented. “It’s beautiful and created entirely from embryonic stem cells.”

The day after the lecture, the researcher released a pre-publication version of the work on a specialized platform.

On the same date, the group’s main academic “rival” in the race for embryonic development, a team led by Jacob Hanna, from the Weizmann Institute of Science, in Israel, also presented a pre-publication article claiming to have achieved similar results.

The Israelis’ work used methods similar to those described by the team led by Żernicka-Goetz.
In previous articles, both groups had already used similar techniques to stimulate stem cells from mice to form structures similar to embryos, including heartbeats.

Also during the annual meeting of the International Society for Stem Cell Research, a third group, led by Jitesh Neupane, from the Gurdon Institute of the University of Cambridge, stated that they managed to go beyond the other researchers, creating a model of a human embryo replicating part the stage of the third or fourth week of pregnancy.

The material was grown from embryonic stem cells and subsequently transferred to a rotating container that served as a kind of artificial uterus.

The structures were deliberately altered so as not to have the tissues that make up the yolk sac and the placenta of natural embryos, which at first makes their development into a fetus unfeasible. Still, the description presented by Neupane indicates that the group managed to get to the point of identifying heartbeats and traces of red blood.

“I would like to emphasize that these are not embryos nor are we actually trying to make embryos,” said Jitesh Neupane, quoted by the Guardian. “These are just models that can be used to analyze specific aspects of human development.”

As research with human embryos older than 14 days of development is prohibited in most countries —including Brazil—, the work has generated criticism about compliance with regulations.

“For me, the great novelty of these studies is that they managed to cultivate the cells in the laboratory for much longer without a uterus”, evaluates the director of the Center for Human Genome Studies and Stem Cells at USP, Mayana Zatz.

The geneticist also highlighted what she considers some weaknesses of the research, emphasizing the limitations for any evaluation, since the works have not yet been published in scientific journals.

The expert criticizes her own decision to state that these are models of synthetic embryos. “It is problematic to say that they are synthetic, because they are cultivated from embryonic stem cells”, emphasized Zatz. Experts from several countries have made similar caveats.

“You have a first cell that forms through the union of the egg and the sperm. This cell starts to divide and, up to a stage of 8 to 16 cells, they are called embryonic stem cells. From what I understand, they they took one of these embryonic cells and cultivated it in the laboratory. Soon it started from something that had already been fertilized, right at the beginning of embryogenesis”, he said.