Embryo-like structures grown in an incubator instead of a uterus could lead to better treatments for infertility and a variety of other medical conditions.
25 Aug 2022
Synthetic embryos made from mouse stem cells have been induced to develop the beginnings of a brain and a beating heart while being grown in the laboratory.
The result is an embryo-like structure that is the closest yet to an embryo developing naturally in the womb, he says. Magdalena Zernicka-Goetz at the University of Cambridge, whose team is also using the same method to make synthetic human embryos, although these are less advanced.
The technique could lead to advances in creating tissues and organs for transplantation and one day be used as a fertility treatment for people who cannot produce sperm or eggs.
Human embryos can usually only be studied in a dish until they are about a week old because at this stage they normally implant in the placenta, which provides oxygen and nutrition. Also, most countries have a rule that human embryos cannot grow beyond 14 days, as after that they could be considered independent life forms.
In 2017, Zernicka-Goetz and her team announced that they could create embryo-like structures that develop over several days by taking some stem cells from a mouse embryo and culturing them alongside trophoblast cells, which normally make up the placenta.
The method sparked worldwide interest as it would allow synthetic embryos to be created on demand and genetically modified to improve our understanding of this mysterious stage of human development. Currently, some unwanted embryos created in IVF clinics can be donated for research, but only a small number are available and they are often affected by medical conditions. “The big question we’re addressing is how do we start our lives,” says Zernicka-Goetz.
Earlier this month, researchers led by jacob anna at the Weizmann Institute of Science in Israel announced that they had made synthetic mouse embryos similar to real embryos 8.5 days after fertilization growing embryonic stem cells together with two other types of helper cells. These were made by genetically altering embryonic stem cells to convert them into placenta-forming cells, as well as a third type of tissue called the endoderm, which normally directs development.
In subsequent steps, the structures were grown in a special rotary incubator with high oxygen pressure.
Now, Zernicka-Goetz and her team have accomplished a similar feat, also using Hanna’s incubator, although they obtained the two types of helper cells by taking them from other embryos. Their synthetic embryos also resembled real embryos at 8.5 days. After this stage, the synthetic embryos begin to die, but teams are trying new approaches to help them survive longer.
Zernicka-Goetz says that the part that becomes the brain is more advanced than in any previous approach, since it includes the developing forebrain. “This is the first model system that can develop all parts of the future brain,” she says.
Hanna, however, says her synthetic embryos are similarly advanced to Zernicka-Goetz’s and contain molecules that signify the development of forebrain tissue. He says that being able to make synthetic embryos from a single source of embryonic stem cells by genetically manipulating them, as his team did, “is a big surprise and a simplified and better method.”
If synthetic embryos could be made from human cells, they could in the future be used to create new sources of cells and tissues to transplant people or cure failing organs, such as livers or hearts. They could also be used to test medications to see if they are safe for pregnancy, says Zernicka-Goetz.
Luis Montoliu at the National Center for Biotechnology in Madrid, Spain, says the creation of synthetic embryos is as important as Dolly the sheep, the first mammal created by cloning an adult body cell. “Without a doubt we are facing a new technological revolution, still very inefficient but with enormous potential,” he said in a statement.
Magazine Reference: Nature, DOI: 10.1038/s41586-022-05246-3
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