Elucidating the signaling pathways that govern differentiation of neural stem cells is central to understanding the development of the central nervous system. Research suggests the involvement of several different molecular pathways which interact to form highly complex signaling cascades. Familes of growth factors known to be important for the development of neural stem cells toward different lineages include bone morphogenetic proteins (BMPs), fibroblast growth factor (FGF), Wnt proteins, and Hedgehog proteins.
Many studies suggest a central role for BMPs in promoting neural stem cell proliferation and differentiation. These findings are often supported by the use of Noggin to antagonize BMP-4 signaling. Although the molecule cascades remain incompletely defined, FGF is commonly used to expand neural stem and progenitor cells in vitro. Equally, Wnt signaling is known to be important for neural stem cell function and development during embryogenesis and in adult brain. In culture, Wnt molecules and Sonic Hedgehog are thought to be essential for promoting the expansion of single cell populations into neurons, astrocytes, and oligodendrocytes.