Role of Microglia in the Regulation of Neural Stem Cells in the Healthy and Injured Brain

Abstract

This chapter is aimed to describe how microglial cells regulate neural stem cells (NSCs), making emphasis on bran-injure conditions without setting aside the healthy brain. Microglia constitute the main immune component of the CNS and, together with astrocytes, are the first line of defense against brain injury, infections, or other aversive stimuli. In normal conditions, microglia help preserve brain homeostasis, but their function is not limited to a defensive role, and they participate in synaptic pruning, regulate neuronal apoptosis, depurate cell debris, and promote myelination. An additional function of microglial cells is the regulation of stem cell niches: the ventricular-subventricular zone (V-SVZ) and the subgranular zone (SGZ) of the hippocampus. Both niches generate new neurons in the adult brain and their neural progenitors are in close contact with microglia, which seem to regulate differentiation and self-renewal of adult neural stem cells (NSCs).