8 Monolayer Cultures of Neural Stem/Progenitor Cells

The central dogma in neuroscience “no new neurons after birth” existed for almost a century. Only in recent years was it believed that neurons are generated exclusively during the prenatal phase of development. The study of adult neurogenesis was started in earnest in 1990s, and it has now become clear that active neurogenesis, a process of generating functionally integrated neurons from undifferentiated multipotent stem or progenitor cells, continues in discrete regions of the adult CNS throughout the life of mammals, including humans. During development, nerve cells in the mammalian CNS are generated by the proliferation of multipotent stem/progenitor cells that migrate, find their site of final destination, and ultimately terminally differentiate. Owing to their relative rarity and lack of specific phenotypic markers, putative stem cells have been characterized based on their functional criteria. The discovery of putative stem cells in a given tissue is usually contingent on the development of in vitro culture conditions enabling a rigorous characterization. According to these criteria, stem cells must demonstrate the ability to proliferate, self-renew over an extended period of time, and generate a large number of progeny (progenitor or precursor cells) that can differentiate into the primary cell types of the tissue from which it was generated (Gage 1998; Temple 2001a,b). The in vitro culture consists of both stem and progenitor cells, and the terms “stem, progenitor, and precursor cells” have been used interchangeably in the literature. In this chapter, I use the term “stem/progenitor cells.” The molecular specification of neural stem/progenitor cells...