For instance, astrocytes from the ventral midbrain are pivotal for the development of DAergic neurons, thanks to the release of an array of pro-survival and neuroprotective molecules [71,72,73,74,75], such as the glial-derived neurotrophic factor (GDNF) [76] and the basic fibroblast growth factor (bFGF) [77], whose levels are altered in PD patients [78,79]. Here, GDNF is linked to Parkinson disease.