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What is really news and what do we know about model embryos?

July 05, 2023

The science behind the headlines.

“Breakthrough!” “A major scientific first!” “The world’s first human synthetic embryos!”

These are some of the breathless headlines that have appeared in the media since researchers announced they had developed embryo models using just stem cells in a presentation at the 2023 annual meeting of the International Society for Stem Cell Research (ISSCR) in Boston.

Some of the media reporting created confusion and missed some important information.

To clarify, these models are NOT ‘real’ embryos. And it wasn’t a world first.

The scientists involved created ‘model embryos’ from stem cells – clusters of cells that allow researchers to study key stages of early human development in the laboratory. They do not have the same potential to develop as a natural human embryo and should not be confused with embryos created from sperm-egg fertilisation nor referred to as ‘synthetic’ embryos.

The first stem cell models to mimic human “blastocysts”, the very early-stage embryo development just prior to implantation, were published in two separate papers in Nature in 2021. Researchers used slightly different approaches to form 3-dimensional structures.  One group, led by inaugural Metcalf Prize winner and Monash University researcher Jose Polo, reprogrammed skin cells before creating embryo models that they called “iblastoids”. At the time, Jose told The Age reporter Liam Mannix, “I do not feel like I have created life.”

“Basically, we just created a good model,” he said. “I am 100 per cent sure, based on all available evidence, that they can only model the very early stages of development, and therefore they cannot develop into a human.”

An embryo-like structure grown by Jose Polo's lab. Credit: Monash University

New research hasn’t been peer reviewed.

Peer review is the self-correcting quality control system that allows experts to check each other’s work, giving broader society confidence in the discoveries scientists make.

“It can be dangerous to report on work without the full picture on how experiments were conducted,” says Professor Megan Munsie, Non-Executive Director of the Foundation.

Megan explains that while scientists are encouraged to talk about their work at conferences, including sharing research findings that are yet to be published, best practice usually sees mainstream reporting only after a paper has been peer-reviewed. 

“This should be especially the case in research that is highly nuanced with complex scientific, ethical and regulatory considerations,” she says.

Scientists are mindful of ethical considerations and guardrails are in place.

While the recent coverage may have left some readers concerned that researchers are operating without any guidance, this is an area that the scientific community have been carefully monitoring.

 “This is an issue that’s being taken very seriously by the scientific community,” Megan explains. “In response to developments, the ISSCR revised their Guidelines for Stem Cell Research and Clinical Translation in 2021 to make it clear that such research must have careful scientific and independent ethical review before any work begins”.

The Guidelines also state that this research must also comply with local laws and policies and limit the length of time the embryo models are grown in the lab.

Why create embryo models in the first place?

These embryo models give scientists new ways to study early human development. Such research sheds light on causes of early pregnancy loss, infertility and the development of certain diseases.

“Stem cell embryo models can provide important insights that we are unable to gain through other research. Appropriate sharing this knowledge with other scientists, and with the community more broadly, will help advance medical research,” says Megan.

Further relevant reading/listening

ISSCR: The ISSCR Statement on New Research with Embryo Models

ABC Science: 'Synthetic human embryos' were created using stem cells. What are they, and why were they made? (from June 2023)

The Conversation: Researchers have grown ‘human embryos’ from skin cells. What does that mean, and is it ethical? (from March 2021)

ABC Radio National Science Friction: 14-day rule on human embryo research – why do scientists want it lifted? (from June 2021)

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