Scientists create ‘synthetic’ mouse embryos that develop a brain, nerve cords and beating heart tissue | UK News


A research team in the UK and US has created ‘synthetic’ mouse embryos that develop a brain, nerve cord and beating heart tissue in the laboratory without the need for a fertilized egg or uterus to grow.

It resembles a breakthrough by an Israeli team that was released earlier this month. Together, the breakthroughs promise to revolutionize understanding of one of biology’s greatest challenges: how a few cells organize themselves for life.

When applied to human embryos, the research could help to better understand human fertility and developmental disorders, and suggest a new way to develop laboratory-grown tissues or organs for transplantation.

But the application of the technique to human embryos would grow important ethical and legal issues.

“The big question we ask ourselves in the laboratory is: How do we start our lives?” says Professor Magdalena Zernicka-Goetz of Caltech in Pasadena, California, and the University of Cambridge in the UK.

To create synthetic embryos, or “embryoids,” the scientists extracted three types of stem cells from a mouse embryo that would normally form all of the tissues needed in a growing embryo.

Then they transferred the cells to an artificial growth medium — essentially a rotating bottle of nutrients.

The stem cells spontaneously formed embryos.

Only about one in 100 was successful, but the few that were successful “in many cases are absolutely indistinguishable from natural embryos,” says Prof. Zernicka-Goetz.

Read more: New project to unravel the mysteries of human embryo development

Prof. Dr. Magda Zernicka-Götz Image: Simon Zernicki-Glover

The embryos developed in just eight and a half days, about half the normal gestation period for a mouse.

But the technique should still be hugely important to produce early embryos that can be used to study early development without the need for laboratory animals.

The team is currently actively working on a human embryo model, but emphasizes that it is still a long way off. There are significant differences between early mouse development and early human development.

But having a synthetic human embryo could be a big step forward for research into fertility and developmental disorders in general.

“Most human pregnancies are lost at very early stages of our lives,” says Prof. Zernicka-Goetz, “and IVF fails 20 to 70% of the time.”

Natural and synthetic embryos side by side to show comparable brain and heart formation.  Image: Credit: Amadei and Handford
Natural and synthetic embryos side by side to show comparable brain and heart formation. Image: Amadei and Handford

The supply of donated human embryos is scarce and often of poor quality, so a lab-grown ‘model’ embryo could help answer many questions.

The team proposes synthetic embryoids that replicate just one element of an early human embryo, such as the heart or the tissue that forms the placenta during implantation. Implantation failure is a major reason for failure of IVF pregnancies.

Synthetic human embryos could also be a way to create new tissues or organs for “regenerative” medicine. If such tissues are derived from the patient’s own stem cells, they could be a perfect match for the recipient.

However, the development of synthetic human embryos would require an amendment to current legislation, at least in the UK, which does not cover the creation of embryos from stem cells.

UK law also prevents human embryos from being grown in the lab for the last 14 days. This is before most of the important developmental processes observed in these mouse embryos take place.

This latest demonstration means that discussion of these legal and ethical issues should begin sooner rather than later, experts say.

“The result indicates that similar experiments will be carried out with human cells in the future and will eventually lead to similar results,” says Prof. Alfonso Martinez Arias of the Universitat Pompeu Fabra in Barcelona, ​​who was not involved in the research.

“This should encourage reflection on the ethics and societal implications of these experiments before they take place,” he added.

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