Researchers grow synthetic human embryos for the first time – the most important in 5 counts

The theme of the creation of an artificial human being – as a dream or nightmare – has a permanent place in cultural history. For example, the Swiss physician and alchemist Paracelsus gave very specific instructions on how to hatch a homunculus in warm horse manure. Of course nothing came of that. Today, at a time when test-tube babies are nothing new and genes are manipulated with extreme precision, things are different.

What a research team from the University of Cambridge and the California Institute of Technology has now achieved brings the possibility of breeding a synthetic human a big step closer. For the first time, the scientists were able to create synthetic embryos using stem cells – without using egg or sperm cells. This is reported by the British Guardian.

Stem cell researcher Magdalena Żernicka-Goetz presented the results of the research work at the Cambridge Caltech laboratory on Wednesday during a talk at the annual meeting of the International Society for Stem Cell Research in Boston. An official scientific publication is not yet available. However, Żernicka-Goetz described that the team succeeded in growing embryos to a stage just beyond the 14-day developmental stage of a natural embryo. The synthetic embryos – the so-called embryoids – are said to closely resemble real human embryos.

When growing synthetic embryos from stem cells, no reproductive cells – ie egg cells or sperm cells – are required. This is in contrast to sexual reproduction, where new life is created by the fusion of the egg and sperm, mixing the parental genetic material. Embryonic stem cells (ES cells) are not found in the adult body; they only appear at a very early stage of embryonic development. They are pluripotent, meaning they are not yet bound to a specific tissue type and have the potential to develop into any “adult” body cell.

The team led by Żernicka-Goetz and a competing research group at the Weizmann Institute of Science in Israel had already succeeded last year in creating artificial mouse embryos using only stem cells. Since then, there has been a race to transfer this work to human models, and several teams have managed to replicate the very early stages of development.

Each structure, grown from a single embryonic stem cell, reached the onset of gastrulation. This is the first stage of cotyledon formation, when the embryo develops from the single-layered blastula to the gastrula, forming the basal axes of the body. At this stage, the embryo does not yet have a beating heart, intestines, or the beginnings of a brain, but the structures contain primordial cells that would normally give rise to the placenta, yolk sac, gamete progenitor cells, and the embryo itself.

“Our human model is the first three-line model of a human embryo that specifies amniotic and germ cells, progenitor cells of egg and sperm cells,” Żernicka-Goetz told the Guardian before her presentation. “It’s beautiful and made entirely from embryonic stem cells.”

Malte Spielmann, director of the Institute of Human Genetics at the University Hospital of Schleswig-Holstein, told the German news agency on Thursday that human embryo-like structures do not yet have body parts or organs. However, cells can be identified that form the basic structures for specific body components. A few days ago, Spielmann saw a lecture in which Żernicka-Goetz presented results on synthetic embryos that were eight days old. “The cells showed very similar signaling pathways and cell types as in real human embryos,” he said.

The scientists want to use the artificial embryos to learn more about early embryonic development. With pregnancy scans and donated embryos for research, they can follow the later development process.

Robin Lovell-Badge, head of the Department of Stem Cell Biology and Developmental Genetics at the Francis Crick Institute in London, told the Guardian:

The advantage of embryo-like structures would be that, in purely legal terms, early embryonic development could potentially be better studied in many countries. Real embryos, which arise after the fusion of sperm and egg cell, enjoy special legal protection. However, this approach raises new ethical questions.

The question of whether these structures theoretically have the potential to grow into a living being is still open. However, it would be illegal to implant them in a woman’s womb anyway, as the Guardian points out. The synthetic embryos grown from mouse cells, which the research team produced last year, almost resembled natural mouse embryos. However, when implanted in the uterus of female mice, they did not develop into live animals.

Something similar happened last April, when researchers in China made synthetic embryos from monkey cells and placed them in the wombs of adult animals. Some of them showed early signs of pregnancy, but none of the embryos developed after a few days. It is not clear whether this has technical reasons or a fundamental biological cause.

The work presented raises serious ethical and legal questions, as lab-grown entities are not regulated in most countries. Many states prohibit the cultivation of human embryos in the laboratory for more than 14 days. They are mainly based on a 2016 guideline from the International Society for Stem Cell Research (ISSCR). Growing embryos in the laboratory for more than 14 days is considered an “impermissible research activity”.

However, the ISSCR amended the guidelines two years ago. Human embryos produced by artificial insemination or from human stem cells should be able to be cultured in the laboratory in the future as long as this serves the respective research purpose. This, of course, only after a strict investigation.

The development shows how quickly science has caught up with legislation in this area, writes the Guardian. Scientists in several countries are already defining voluntary guidelines for working with synthetic embryos. Lovell-Badge told the newspaper:

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With material from the SDA news agency.