TH and Parkinson disease: EVs derived from the human teeth stem cells successfully normalize the expression of tyrosine hydroxylase (TH) in the substantia nigra (SN) and striatum of 6‐OHDA‐induced PD in rats and reverse the impairment of spatial learning/memory performance, such that the escape latency to find the platform in MWM decrease, and spent time in the target quadrant increase after the treatment.106