Extracellular Vesicles from Adipose Mesenchymal Stem cells: a therapeutic strategy for neurodegenerative diseases

Neurodegenerative diseases are fatal disorders of the central nervous system which currently lack effective treatments. The application of adipose-derived mesenchymal stem cells (ASCs) represents a new promising approach for treating these incurable disorders. Growing evidence suggest that the therapeutic effects of ASCs are due to the secretion of neurotrophic molecules through extracellular vesicles (EVs). The EVs produced by ASCs (ASC-EVs) have valuable innate properties deriving from parental cells and could be exploited as cell-free treatments for many neurological diseases. The aim of this PhD project was to evaluate the therapeutic effect of ASC-EVs in different in vivo and in vitro models of neurodegeneration, with a particular focus on Amyotrophic Lateral Sclerosis (ALS) and Spinal Muscular Atrophy (SMA). SMA is an autosomal-recessive neuromuscular disease caused by the mutation or deletion of the survival motor neuron 1 (SMN1) gene. In this study, ASC-EVs were administered via intracerebroventricular injections in SMNΔ7 mice, a severe SMA model. The results showed positive effects of ASC-EVs on the disease progression, with improved motor performance and a significant delay in spinal motor neurons (MNs) degeneration of treated animals. ASC-EVs could also reduce the apoptotic activation and modulate the neuroinflammation with an observed decreased glial activation in lumbar spinal cord, while at peripheral level ASC-EVs could only partially limit the muscular atrophy and fibers denervation. ALS is a fatal neurodegenerative disease characterized by progressive degeneration of MNs. Here, we tested the potential therapeutic effect of ASC-EVs on a murine model commonly used to study ALS, the SOD1(G93A) transgenic mouse. We compared the effect of two different routes of ASC-EVs administration: intravenous and intranasal (i.n.). Our results demonstrated that repeated administration of ASC-EVs improved the motor performance, protected lumbar MNs, the neuromuscular junctions and muscle, and decreased the glial cells activation in treated SOD1(G93A) mice. Furthermore, we compared different concentration and frequencies of administration of ASC-EVs injected intranasally in order to individuate the correct administration regimen to obtain the more significant therapeutic effect. Moreover, we use an in vitro model of epithelial RPMI 2650 cells to investigate the mechanisms used by ASC-EVs to overcome biological barriers encountered once administered in the human body. The neuroprotective effect of ASC-EVs was also evaluated on both damaged in vitro MN and neuron cells (NSC-34 and SH-SY5Y cells respectively) after their passage through the epithelial cellular layer. The results showed that ASC-EVs neuroprotective effects observed in previous studies were maintained after their passage through the epithelial barrier as well, with a rescue of the neuronal cells viability after oxidative stress. In addition, a strategy for EVs labelling has been set up to detect and confirm their capability of migration and internalization by injured cells.