Intranasal Administration of Extracellular Vesicles Derived from Human Teeth Stem Cells Improves Motor Symptoms and Normalizes Tyrosine Hydroxylase Expression in the Substantia Nigra and Striatum of the 6-Hydroxydopamine-Treated Rats

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting millions of people worldwide. At present, there is no effective cure for PD; treatments are symptomatic and do not halt progression of neurodegeneration. Extracellular vesicles (EVs) can cross the blood–brain barrier and represent promising alternative to the classical treatment strategies. In the present study, we examined therapeutic effects of intranasal administration of EVs derived from human exfoliated deciduous teeth stem cells (SHEDs) on unilateral 6‐hydroxydopamine (6‐OHDA) medial forebrain bundle (MFB) rat model of PD. CatWalk gait tests revealed that EVs effectively suppressed 6‐OHDA‐induced gait impairments. All tested gait parameters (stand, stride length, step cycle, and duty cycle) were significantly improved in EV‐treated animals when compared with 6‐OHDA‐lesion group rats. Furthermore, EVs slowed down numbers of 6‐OHDA‐induced contralateral rotations in apomorphine test. Improvements in motor function correlated with normalization of tyrosine hydroxylase expression in the striatum and substantia nigra. In conclusion, we demonstrated, for the first time, the therapeutic efficacy of intranasal administration of EVs derived from SHEDs in a rat model of PD induced by 6‐OHDA intra‐MFB lesion. Our findings could be potentially exploited for the development of new treatment strategies against PD

Extracellular Vesicles from Human Teeth Stem Cells Trigger ATP Release and Promote Migration of Human Microglia through P2X4 Receptor/MFG-E8-Dependent Mechanisms

Extracellular vesicles (EVs) effectively suppress neuroinflammation and induce neuroprotective effects in different disease models. However, the mechanisms by which EVs regulate the neuroinflammatory response of microglia remains largely unexplored. Here, we addressed this issue by testing the action of EVs derived from human exfoliated deciduous teeth stem cells (SHEDs) on immortalized human microglial cells. We found that EVs induced a rapid increase in intracellular Ca2+ and promoted significant ATP release in microglial cells after 20 min of treatment. Boyden chamber assays revealed that EVs promoted microglial migration by 20%. Pharmacological inhibition of different subtypes of purinergic receptors demonstrated that EVs activated microglial migration preferentially through the P2X4 receptor (P2X4R) pathway. Proximity ligation and co-immunoprecipitation assays revealed that EVs promote association between milk fat globule-epidermal growth factor-factor VIII (MFG-E8) and P2X4R proteins. Furthermore, pharmacological inhibition of αVβ3/αVβ5 integrin suppressed EV-induced cell migration and formation of lipid rafts in microglia. These results demonstrate that EVs promote microglial motility through P2X4R/MFG-E8-dependent mechanisms. Our findings provide novel insights into the molecular mechanisms through which EVs target human microglia that may be exploited for the development of new therapeutic strategies targeting disease-associated neuroinflammation