The study, published today in Proceedings of the National Academy of Sciences of the United States of America, describes how stem cells self-organise to form embryonic tissues.

Protein signals, that act as messengers between cells, control the function of many cell types. This discovery shows that certain stem cells use a highly specific method of coming into contact with particular protein signals known as Wnts and has surprising similarities to the synapses that control cell interactions in the brain.

Stem cells are the building blocks of tissues, which ultimately produce the cells that form adult organs and tissues. They are bombarded by many signals, but must carefully balance their responses to both maintain their own population and to differentiate into other cells. 

The findings show how specialised finger-like extensions that embryonic stem cells generate to detect and interact with the cells that will become the placenta. Following this interaction, the cells generate structures that resemble the synapse – the connection between neurons - between the cells, enabling stable cell to cell communication. This communication is essential and promotes, in a lab environment, the formation of structures that resemble the early mouse embryo.

Understanding how communication between these cells works may be crucial to the engineering of more complex tissues in the lab. These lab-grown tissues may then prove pivotal for drug screening and understanding how organisms grow.

This novel discovery, which builds on previous findings from the Habib group, could also be relevant to other stem cells in the adult body and can provide opportunities to alter this activity during disease, such as cancer, and for repairing tissues through regenerative medicine.