However, there have been few detailed reports concerning the glial response to NSC transplantation in PD; Thirdly, previous evidence has suggested that astrocytes, particularly the EDAs are central to endogenous neuroprotection by release of neurotrophic factors such as glial cell line-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), neurotrophin-3 (NT-3), and epidermal growth factor (EGF), etc. [20,21,22]. This evidence concerns the gene GDNF and Parkinson disease.