[Problem] To provide a cell culture method which can achieve the increase in safe expression of GDNF gene (mRNA) without needing to employ a gene transfer method using a virus. [Solution] A method for producing a cultured cell containing mRNA for glial cell line derived neurotrophic factor (GDNF), the method including a culture step of culturing a human skin-derived stem cell in a serum-free culture medium containing at least one component selected from SAG, purmorphamine and sonic hedgehog (SHH) protein, wherein the serum-free culture medium may additionally contain a B-27 supplement, a ROCK inhibitor, EGF and FGF2.
