NGF and brain ischemia: After cerebral ischemia, RAs secrete a variety of nutritional factors, including nerve growth factor (NGF), bFGF, BDNF, GDNF, vascular endothelial growth factor (VEGF) (Liu and Chopp, 2016), erythropoietin (EPO) (Roe, 2017) and neurotrophin-3 (NT-3) (Jurič et al., 2011), which can promote the regeneration of axons and blood vessels, the formation of myelin sheath, and synaptic plasticity.