Comprehensive Characterization and in vitro Functionality Study of Small Extracellular Vesicles Isolated by Different Purification Methods from Mesenchymal Stem Cell Cultures

Mesenchymal stem cells (MSCs) exhibit therapeutic properties, which have been attributed to their secretome, the set of secreted factors comprising cytokines, growth factors, and extracellular vesicles (EVs). In particular, small extracellular vesicles (sEVs) or exosomes, ranging between 30 nm and 120 nm in diameter, can target specific tissues to deliver molecular payloads, thus lending themselves as promising platform for cell-free therapies. In this study, sEVs were fully characterized after purification using size-exclusion chromatography (SEC) or density gradient ultracentrifugation (DG-UC) from the conditioned medium (CM) harvested from human bone marrow-derived MSC culture. Then, the in vitro functionalities of MSC-sEVs with cell-based bioactivity assays were evaluated.