GDNF and Stroke: To prove this hypothesis, researchers have tried to upregulate various trophic factors such as BDNF, VEGF, glial cell-derived neurotrophic factor (GDNF), hepatocyte growth factor (HGF), placental growth factor (PIGF), and fibroblast growth factor 2 (FGF2) in human MSCs and found functional improvement after stroke, compared to naïve MSCs [33, 38–40, 43–47].