Proteoglycans of the Neural Stem Cell Niche

Neural stem cells (NSCs) of the central nervous system (CNS) follow a precisely timed sequence of neurogenesis and gliogenesis, before they generally vanish after birth. In the adult CNS residual NSCs can be detected in two neurogenic regions, the subependymal zone (SEZ) of the lateral ventricle and the subgranular zone (SGZ) in the dentate gyrus of the hippocampus. These regions present favorable environments for stem cells and are considered privileged niches for their persistence and differentiation. Niches comprise the stem cells, their progeny, specialized niche cells, and a specialized extracellular matrix (ECM) environment. Morphogens, cytokines, hormones, and glycoproteins contribute to a rich microenvironment that guides self-renewal and/or differentiation of stem cells. It has become evident that a subclass of ECM constituents is of particular importance for the structure and function of the stem cell niche, the proteoglycans (PGs). PGs can embody a considerable structural variability and intervene in many important cellular functions such as cell proliferation, migration, and differentiation. A better understanding of niche PGs and their regulatory roles will be valuable for the design of artificial growth support of stem cells. This chapter discusses recent insights into the composition and functions of PGs in the microenvironment of NSCs.