Thus, HGF, as a paracrine factor, may contribute to successful stem-cell-based therapies, which have been investigated in many clinical trials in the context of pathologies such as SCI, PD, ALS, AD, and MS with promising results (Jafarzadeh Bejargafshe et al., 2019; Staff et al., 2019; Platt et al., 2020; Silvestro et al., 2020). Here, HGF is linked to Parkinson disease.