VEGFA and Stroke: For example, astrocytes release many bioactive substances and regulatory factors that promote BBB function (Alvarez et al., 2013) including sonic hedgehog (Shh), which regulates TJ development and BBB permeability; nitric oxide (NO), which regulates vasodilation (Iadecola and Nedergaard, 2007); and vascular endothelial growth factor (VEGF), which is involved in angiogenesis and vasogenic edema during stroke (Davis et al., 2010).