Studies on mechanism of extracellular vesicle production by membrane transport of calcium ion under shear stress

Abstract

Extracellular vesicles (EVs) are nano-sized vesicles that cells release into the extracellular space. They contain materials from the host cell (RNAs, proteins and lipids). The host cell materials deliver the information to recipient cells as a cell communicator. EVs derived from mesenchymal stem cells have genetic materials derived from them, and thus have therapeutic efficacy in various disease models. However, the amount of EVs released from cells is too small to be useful as therapeutic agents. In this thesis, mechanisms of high production of EVs under shear stress are demonstrated. Shear stress is controlled by flow in a flat-plate bioreactor and shaking culture. The yield of EVs released under shear stress was up to seven times higher than from static culture. The mechanism of high production of EVs under shear stress studied in relation to intracellular concentration of calcium ions. These ions are transferred through cell membranes into cells cultured under shear stress, and intracellular Ca2+. The expression of proteins involved in EV biogenesis is higher in EVs released under the condition of increased intracellular Ca2+ than under static condition. EV production is induced by the condition of increased intracellular Ca2+ under shear stress. To verify the function of EVs released under shear stress, their therapeutic efficacy of EVs was investigated on an acute kidney-injury model in vitro and in vivo. The acute kidney injury model regenerated in vitro and in vivo, and EVs released under shear stress had therapeutic efficacy and maintained function. This thesis is a study of the increased release of EVs under shear stress, the mechanism of enhanced production of EVs, and the function of EVs about therapeutic efficacy. Therefore, this study is expected to contribute to research on therapeutic agents and various applications that use EVs.