Researchers have developed synthetic embryos made from mouse stem cells in a lab to form a rudimentary brain and a beating heart.
The embryo-like structuresfrom an incubator instead of a womb, could lead to better treatments for infertility and other medical conditions.
Better than previous attempts, the structures come close to a true-to-life embryo, says co-author, professor of mammalian development and stem cell biology Magdalena Zernicka-Goetz from the University of Cambridge in the United Kingdom. Her team is also developing synthetic human embryos, but these are less developed.
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This technique could further aid science in creating tissue and organs for transplants. Also, this approach could one day lead to infertility treatment for people who don’t produce sperm or eggs.
Placenta problems
Researchers can normally only study human embryos in a petri dish for a week, because the embryos then have to implant in the placenta, where they receive oxygen and nutrition. In addition, many countries have legislation that states that human embryos cannot be older than 14 days, as they are then considered an independent life form.
In 2017, Zernicka-Goetz and her team announced that they had succeeded in creating embryo-like structures that continued to develop for a few days. They did this by growing a number of stem cells from a mouse embryo together with trophoblast cells (trophoblast cells normally form the placenta later in the process).
How life begins
This method received worldwide attention because it allows you to make synthetic embryos ‘on order’. In addition, you can genetically modify the embryos so that you can use them to better understand this mysterious stage of human development. “The big question we are raising is how we start our lives,” says Zernicka-Goetz.
At present, people can donate unwanted embryos to IVF clinics for research. However, that is only a small number of donations, where medical conditions are often still found.
Earlier this month, researchers led by assistant professor of molecular genetics Jacob Hanna of the Weizmann Institute of Science in Israel already known that they had made synthetic mouse embryos which resembled real embryos as they appear about 8.5 days after fertilization.
Special incubator
They did this by growing embryonic stem cells along with two other types of auxiliary cells. These auxiliary cells were genetically modified embryonic stem cells, which formed both placenta-forming cells and a third type of tissue: the endoderm, which also directs the development of an embryo.
Zernicka-Goetz and her team have now put in a similar feat, though they got the two types of helper cells from other embryos. These synthetic embryos also resembled real 8.5-day-old embryos. At the moment, the synthetic embryos don’t survive beyond this stage, but the teams are trying to come up with solutions for that.
The part of the embryo that makes up the brain is more complex than with all previous methods. In this case, it also contains developing forebrain, Zernicka-Goetz says. ‘This is the very first model system that can actually develop all parts of a new brain.’
Future Applications
However, Hanna says that his synthetic embryos are about as advanced as Zernicka-Goetz’s, and that they also contain molecules that indicate the development of forebrain tissue. Making synthetic embryos from only genetically modified embryonic stem cells, as his team did, is, according to Hanna, ‘a big surprise and is a better and simplified method’.
If scientists can create synthetic embryos from human cells, we could use them as a source of cells and tissues in the future. That would be useful for transplants or repairing failing organs such as the liver or heart. They could also be used to test drugs to see if they are safe to take during pregnancy, Zernicka-Goetz says.
Lluis Montoliu, vice director of the National Biotechnology Center in Madrid, Spain, says creating synthetic embryos is just as important as creating Dolly the sheep, the first mammal made from a cloned adult body cell. “We are undoubtedly facing a new technological revolution – still very inefficient but with enormous potential,” he said in a statement.