GDNF and Parkinson disease: MSCs can thus serve as carriers for genes whose expression is needed in specific neurological disorders: GDNF (PD and ALS),91, 92 VEGF (PD),93 GDNF and VEGF (ALS),94 BDNF (Huntington's disease [HD], SCI, and stroke),95, 96, 97 conserved dopamine neurotrophic factor,98 and PlGF (stroke).99