Neural stem cell engineering: directed differentiation of adult and embryonic stem cells into neurons

Both adult neural stem cells and embryonic stem cells have shown the capacity to differentiation into multiple cell types of the adult nervous system. They will therefore serve as valuable systems for basic investigations of cell fate choice mechanisms, as well as play important future roles in applications ranging from regenerative medicine to drug screening. However, there are significant challenges remaining, including the identification of signaling factors that specify cell fate in the stem cell niche, the analysis of intracellular targets and mechanisms of these extracellular signals, and the development of ex vivo culture systems that can exert efficient control over cell function. This review will discuss progress in the identification of signaling mechanisms and culture systems that regulate neural differentiation, neuronal differentiation, and neuronal subtype specification.