GDNF and amyotrophic lateral sclerosis: Our chemical induction method significantly upregulated various trophic factors (Fig 3B), such as BDNF, GDNF, NGF, and NT-3, which have been reported to have therapeutic effects in neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease [45], and Amyotrophic lateral sclerosis [46].