GDNF and Stroke: Transplantation of gene modified-stem cells overexpressing diverse neurotrophic factors such as VEGF, BDNF, GDNF, PIGF, ANG-1, HGF, NGF, EPO, and noggin has been demonstrated to significantly improve the functional recovery in stroke compared to stem cells only [13, 111, 122, 133, 170, 180–183].