Adipose-Derived Mesenchymal Stem Cell Exosomes Attenuate Oxygen-Glucose Deprivation-Induced Cochlear Damage by...

Ischemia plays a critical role in the pathogenesis of sensorineural hearing loss through the induction of severe cochlear apoptosis and mitochondrial dysfunction. Exosomes derived from adipose-derived mesenchymal stem cells (ADMSC-Exo) have robust protective effects under non-otologic ischemic conditions. However, their otoprotective effects remain unclear. This study aimed to investigate the protective effects of human ADMSC-Exo against cochlear damage and mitochondrial dysfunction under oxygen-glucose deprivation (OGD), an in vitro and ex vivo model of cochlear ischemia. ADMSC-Exo attenuated OGD-induced cytotoxicity and apoptosis in HEI-OC1 cells and reduced the OGD-induced loss of cochlear hair cells in the organ of Corti explants. OGD caused a decrease in mitochondrial mass and mitochondrial membrane potential depolarization and impaired mitochondrial respiration in auditory cells. ADMSC-Exo preserved mitochondrial integrity and improved mitochondrial bioenergetic function following OGD exposure. These effects were accompanied by increased LC3-II conversion and formation of autolysosome-like structures and elevated expression of PINK1 and Parkin, indicating the activation of autophagy and mitophagy-related protective mechanisms. Importantly, 3-methyladenine, an autophagy inhibitor, attenuated the cytoprotective effect of ADMSC-Exo, supporting the involvement of autophagy in ADMSC-Exo-mediated protection. Collectively, these findings suggest that ADMSC-Exo protect against OGD-induced cochlear injury by promoting autophagy-associated mitochondrial protection.