The physical entrapment of glial cell line-derived neurotrophic factor (GDNF) within fluorenylmethoxycarbonyl-aspartic acid-isoleucine-lysine-valine-alanine-valine (Fmoc-DIKVAV) hydrogels has been used for neural transplants in Parkinson’s disease models, improving graft cell survival, host tissue reinnervation, and tissue repair [356]. This evidence concerns the gene GDNF and Parkinson disease.