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a b

c

d e
Figure 3: Schematic representation of the demyelination and remyelination processes. (a) in a basal condition, type A neuroblasts and oligodendrocyte precursor
cells (OPCs) are continuously generated from neural stem cells, with neuroblasts being the great majority progeny; (b) after a demyelinating episode, nearby
astrocytes and microglia are activated and release inflammatory mediators, increasing the permeability of the blood‑brain barrier (BBB). By releasing chemokines,
astrocytes recruit more microglial cells to the demyelinated area; (c) which phagocyte dead cells and myelin debris, as do macrophages that have crossed the BBB.
Astrocytes and macrophages act as antigen-presenting cells to T lymphocytes that are then activated and attack the myelin sheath and dying cells. B lymphocytes
produce autoantigens against myelin antigens functioning as opsonins; (d) microglia, macrophages, and astrocytes release mediators that mobilize parenchymal
OPCs to proliferate, migrate, and differentiate into new myelinating oligodendrocytes in the demyelinated area. After a demyelinating episode, OPC production in the
subventricular zone (SVZ) is favored in detriment of neuronal precursor cells. These SVZ-derived OPCs migrate to the demyelinated areas where they differentiate
into mature myelinating oligodendrocytes; (e) new myelinating oligodendrocytes form a thinner myelin sheath around the demyelinated axon

IGF‑1, brain‑derived neurotrophic factor (BDNF), The extracellular matrix composition of the vascular
chemokines, among others, which also influence stem basal lamina makes the basal lamina an important
cell self‑renewal, proliferation, and fate determination integration site for the exchange of signals between
in the SVZ [Figure 2]. [44‑46,49] In addition, cerebral the SVZ progenitors and the main compartments of
endothelial cells promote differentiation of SVZ the SVZ niche, the vasculature and the CSF, because it
NSCs into oligodendrocytes, being important for the provides, stores, and compartmentalizes growth factors
proliferation and migration of OPCs. [42] and cytokines. [42,45]

266 Neuroimmunol Neuroinflammation | Volume 2 | Issue 4 | October 15, 2015 Neuroimmunol Neuroinflammation | Volume 2 | Issue 4 | October 15, 2015 267