VEGFA and Parkinson disease: A 2.5-fold increase in the number of BECs is identified in the substantia nigra pars compacta of PD brain tissue, where the proangiogenic molecule vascular endothelial growth factors (VEGF) correspondingly upregulated because of the astrocytes activated by oligomeric α-synuclein (Faucheux et al., 1999; Wada et al., 2006).