Another Parkinson’s disease (PD) trial (NCT02611167) demonstrated that a single intravenous infusion of allogeneic BM-MSCs significantly reduced peripheral inflammation (P < 0.05), increased brain-derived neurotrophic factor levels (P < 0.05), and improved the OFF status (OFF:12-h medication withdrawal before assessment) in all patients (Schiess et al., 2021). This evidence concerns the gene BDNF and Parkinson disease.