In Parkinson’s disease research, these naturally derived, in situ-forming, injectable scaffolds have been proven to improve the survival, re-innervation and functional capability of intrastriatal transplanted fetal dopaminergic neurons when used alone or in conjunction with the neurotrophin, glial cell line-derived neurotrophic factor (GDNF), in a rodent model of Parkinson’s disease [13,14]. This evidence concerns the gene GDNF and Parkinson disease.