How are embryonic stem cells stimulated to differentiate into specialised cells?
A. As long as embryonic stem cells are grown under certain conditions, they remain unspecialised. However, if they are allowed to clump together to form embryoid bodies, they begin to differentiate spontaneously, forming specialised muscle cells, nerve cells, and many other cell types. Although this spontaneous differentiation is a good indication that a culture of embryonic stem cells is healthy, it is not an efficient way to produce cultures of specific cell types. To generate specific types of differentiated cells – for example, heart muscle cells, blood cells or nerve cells – researchers need to learn how to control and direct the specialisation of embryonic stem cells. They can change the chemical composition of the culture medium, alter the surface of the culture dish, or modify the cells by inserting specific genes. Through years of experimentation scientists have established some basic protocols or ‘recipes’ for directing embryonic stem cells to become some specific cell types.
