We knew that interactions between the different types of stem cell are important for development, but the striking thing that our new work illustrates is that this is a real partnership – these cells truly guide each other.
- Magdalena Zernicka-Goetz
Understanding the very early stages of embryo development is of interest because this knowledge may help explain why a significant number of human pregnancies fail at this time.
Once a mammalian egg has been fertilised by a sperm, it divides multiple times to generate a small, free-floating ball of stem cells. The particular stem cells that will eventually make the future body, the embryonic stem cells (ESCs) cluster together inside the embryo towards one end: this stage of development is known as the blastocyst. The other two types of stem cell in the blastocyst are the extra-embryonic trophoblast stem cells (TSCs), which will form the placenta, and primitive endoderm stem cells that will form the so-called yolk sac, ensuring that the foetus’s organs develop properly and providing essential nutrients.
Previous attempts to grow embryo-like structures using only ESCs have had limited success. This is because early embryo development requires the different types of cell to coordinate closely with each other.
However, in a study published in the journal Science, Cambridge researchers describe how, using a combination of genetically-modified mouse ESCs and TSCs, together with a 3D scaffold known as an extracellular matrix, they were able to grow a structure capable of assembling itself and whose development and architecture very closely resembled the natural embryo.
“Both the embryonic and extra-embryonic cells start to talk to each other and become organised into a structure that looks like and behaves like an embryo,” explains Professor Magdalena Zernicka-Goetz from the Department of Physiology, Development and Neuroscience, who led the research. “It has anatomically correct regions that develop in the right place and at the right time.”
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Image: Stem cell-modelled embryo at 96 hours (left); Embryo cultured in vitro for 48 hours from the blastocyst stage (right)
Credit: Sarah Harrison and Gaelle Recher, Zernicka-Goetz Lab, University of Cambridge
Reproduced courtesy of the University of Cambridge
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