Therapeutic effects of MSC-derived EVs intranasally administered on ALS mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by death of upper and lower motor neurons (MNs) with no effective therapies. Our previous results revealed that a single intravenous administration of mesenchymal stem cells (MSCs) prolonged survival probability and ameliorated pathological features, including gliosis and neuroinflammation, in the SOD1G93A mouse model of ALS. We postulated that the beneficial effect could be mediated by the paracrine activity of extracellular vesicles (EVs) secreted by MSCs shuttling microRNA. Subsequently, we demonstrated in-vitro the activity of MSCs-derived EVs on mouse and human ALS astrocytes in modulating the aberrant reactive phenotype, which in turn reduced the pathological release of pro-inflammatory factors and the accumulation of reactive oxygen species. Moreover, the exposure to MSCs-derived EVs significantly reduced the neurotoxicity of mouse and human ALS astrocytes towards co-cultured MNs. As a translational step, we here investigated the in-vivo efficacy of the chronic administration of MSC-derived EVs in symptomatic SOD1G93A. Male and female animals were intranasally administered, twice a week, with 10e9 MSC-derived EVs or vehicle solution, starting at the early symptomatic stage of the disease (80 days of life). Two-photon microscopy images demonstrated that MSC-derived EVs efficiently get into the CNS after intranasal administration. The behavioral studies confirmed that MSC-derived EVs administration significantly ameliorates motor function scores and survival probability. While ex-vivo histological studies showed no significant effects on glial reactivity and neuroinflammatory parameters, EVs-treated animals demonstrated spinal cord MNs preservation and improved antioxidant response compared to control mice. The NFL serum levels, monitored at the end stage, were only partially reduced by EVs treatments. Overall, our data pave the way for the application of MSCs-derived EVs as a promising therapeutic strategy for ALS cure.