In summary, we provide evidence for the following: (1) Transgenic GDNF does not affect pluripotency of mESCs; (2) The positive effects of sustained GDNF release on dopaminergic differentiation in vitro; (3) GDNF-ESC are less sensitive to the toxic action of 6-OHDA; (4) After grafting, both CTRL- and GDNF-ESC induced behavioral recovery and DA release in the brain of lesioned animals; (5) GDNF in genetically modified mESC-derived DaNs increased the number of surviving DaNs in the brains of a rodent model of PD. This evidence concerns the gene GDNF and Parkinson disease.