Embryonic stem cells: Understanding their history, cell biology and signalling

Embryonic stem cells offer enormous potential as a source of a variety of differentiated cells for cell therapy, drug discovery and toxicology screening. With the creation of human embryonic stem cell lines we now have a resource with the potential to differentiate into every tissue of the body. To fully harness this resource it is necessary to understand their biology. Here we give a background to their history, describe interesting elements of their cell biology and introduce the underlying signalling mechanisms that control their ability to self-renew and differentiate.