BDNF and nervous system disorder: Compared with NSCs, the effectiveness of MSCs as documented in models of neurological disease is attributed mainly to the cells’ ability to secrete various neurotrophins, cytokines, or growth factors, including brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF), all of which possibly contribute to the functional recovery of the subventricular zone (SVZ) in the adult central nervous system [23, 31, 32].