Characterization of oligodendrocyte-derived extracellular vesicles across cell differentiation

Oligodendrocytes (OLs) are the myelinating glia of the central nervous system (CNS), and their dysfunction is a hallmark of several neurodegenerative disorders such as multiple sclerosis. Intercellular communication pathways between OLs and other cell types in the CNS is critical for the proper formation and maintenance of the myelin sheath. Extracellular vesicles (EVs) are a heterogeneous population of secreted membrane vesicles that differ in biogenesis, cargo, and biological functions they exhibit on target cells. One relatively unexplored avenue is the autocrine regulation of myelination mediated by EVs, and given their variety in cargo, potentially they could be involved in this process. However, very little is known about the molecular cargo of OL-derived EVs and nothing is known about how OL-EV cargo changes throughout cell differentiation. This study aims to determine how the molecular composition and functional effects of EVs change over OL cell development using the CG4-OL cell line. Relative to the EV associated marker TSG101, the constitutive secretion of EVs containing the tetraspanin markers CD44, CD63 and CD81 remained consistent across cell differentiation. On the other hand, the expression of CD9 increased suggesting a different population of exosomes and/or microvesicles are secreted from mature OLs. These EVs also had an increase in the cell signaling protein 14-3-3. Treatment of CG4-OL cells with OL-derived EV isolated at different stages resulted in no difference in genes associated with progenitor state (Ki67 and Pdgfra) and of the myelin genes, a significant increase (p<0.05) in relative Mog mRNA expression was observed in samples treated with supernatant collected from D0 and D6. Data presented in this thesis, for the first time, characterizes OL derived EVs isolated across cell differentiation and assessed their ability to act as autocrine factors on OL proliferation and differentiation.