mouse artificial embryo

This image shows stem cell-modeled mouse embryo at 96 hours (left); Mouse embryo cultured in vitro for 48 hours from the blastocyst stage (right). The red part is embryonic and the blue extra-embryonic / Sarah Harrison and Gaelle Recher, Zernicka-Goetz Lab, University of Cambridge

Scientists at the University of Cambridge have created in vitro a structure that resembles a mouse embryo. Stem cells grown outside the body were induced to develop into primitive embryos that looked and functioned almost exactly like their natural counterparts. 

The embryos were allowed to develop in culture for seven days, approximately one third of a mouse gestation, and during that time the cells organised into two distinct sections that would normally become the placenta and the embryonic mouse. 

More on this: Scientists reprogram embryonic stem cells to expand their potential cell fates

Published in the journal Science, these results represent a significant advance in studying early embryonic development. “This is the time of implantation when the embryo is invading the body of the mother,” said Professor Magdalena Zernicka-Goetz from the Department of Physiology, Development and Neuroscience, who led the research. “Weeks later you can observe it with ultrasound but at this stage it is very mysterious. It’s a developmental black box.”

Previous attempts to grow embryo-like structures using embryonic stem cells have had limited success. Zernicka-Goetz and her team used both embryonic and trophoblast (those that go on to form the placenta) stem cells, and identified a high level of communication between these types of cells that is directly linked to normal development.

“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,” explained Zernicka-Goetz.

“Without this partnership, the correct development of shape and form and the timely activity of key biological mechanisms doesn’t take place properly.”

This latest development could address a serious problem in human fertility research, namely a shortage of embryos. Currently, embryos are developed from eggs donated through IVF clinics, but not in great enough numbers to properly facilitate research. 

“We think that it will be possible to mimic a lot of the developmental events occurring before 14 days using human embryonic and extra-embryonic stem cells using a similar approach to our technique using mouse stem cells,” she says. “We are very optimistic that this will allow us to study key events of this critical stage of human development without actually having to work on embryos. Knowing how development normally occurs will allow us to understand why it so often goes wrong.”

The Cambridge team are not the only ones looking for innovative ways to study early embryonic development. Scientists at the recently-opened Crick Institute in London, UK, are investigating this early 14 day window using different approach: gene editing using CRISPR/Cas9