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We aimed to investigate the effect of morin hydrate on neural stem cells (NSCs) isolated from mouse inner ear and its potential in protecting neuronal hearing loss. 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) and bromodeoxyuridine incorporation assays were employed to assess the effect of morin hydrate on the viability and proliferation of in vitro NSC culture. The NSCs were then differentiated into neurons, in which neurosphere formation and differentiation were evaluated, followed by neurite outgrowth and neural excitability measurements in the subsequent in vitro neuronal network. Mechanotransduction of cochlea ex vivo culture and auditory brainstem responses threshold and distortion product optoacoustic emissions amplitude in mouse ototoxicity model were also measured following gentamicin treatment to investigate the protective role of morin hydrate against neuronal hearing loss. Morin hydrate improved viability and proliferation, neurosphere formation and neuronal differentiation of inner ear NSCs, and promoted in vitro neuronal network functions. In both ex vivo and in vivo ototoxicity models, morin hydrate prevented gentamicin‐induced neuronal hearing loss. Morin hydrate exhibited potent properties in promoting growth and differentiation of inner ear NSCs into functional neurons and protecting from gentamicin ototoxicity. Our study supports its clinical potential in treating neuronal hearing loss.

Both exosomes derived from neural progenitor cells (NPCs) can suppress inflammation. Whether exosomes derived from miR-21-transfected NPCs (miR-21-Exo) could be utilized to alleviate hearing loss is investigated. NPCs were transfected with lentiviral vectors overexpressing miR-21, and miR-21-Exo was purified. Morphology and exosome membrane markers were examined with nanoparticle tracking analysis, transmission electron microscopy, and Western blot. After incubation with different concentrations of miR-21-Exo, the viability of RAW 264.7 cells and the relative expressions of miR-21 and IL-10 were determined. The ischemia and reperfusion (I/R) model of C57BL/6 J mice was constructed, and the treatment benefit of miR-21-Exo was revealed by the auditory brainstem response (ABR) test. Immunofluorescence staining of caspase-3 and parvalbumin was used to detect apoptosis hair cells in the cochlea, and Western blot was utilized to detect the relative expressions of P53 and inflammatory cytokines in the cochlea. Isolated exosomes were confirmed by the size of 96 ± 25 nm, single membrane, and positive expression of CD9 and Tsg101. Upregulated miR-21 expression was detected in miR-21-transfected NPCs and miR-21-Exo. miR-21-Exo incubation demonstrated no cytotoxicity but upregulated miR-21 and IL-10 expressions in RAW 264.7 cells. The administration of miR-21-Exo inhibited the increased ABR threshold under 8, 16, and 32 kHz frequencies in cochlea-I/R injury mice and diminished the mean fluorescent intensity of caspase-3/parvalbumin. Moreover, miR-21-Exo treatment increased the IL-10 expression and prevented the increased TNF-α and IL-1β expressions in the cochlea of I/R mice both in mRNA and protein levels. Inner ear administration of miR-21-Exo effectively improved hearing damage caused by I/R.

<b><i>Introduction:</i></b> Tumor exosome-derived miRNAs play important roles in the human laryngocarcinoma. However, it is still unknown if exosome miR-552 is involved in the laryngocarcinoma. The aim of the current study was to explore exosome miR-552’s role in laryngocarcinoma and its underlying mechanisms. <b><i>Methods:</i></b> Hep-2 exosome was characterized by transmission electron microscopy and nanoparticle tracking technology. CCK-8 was used to determine cell viability, and a xenograft animal model was used to determine the tumorigenicity. qPCR and Western blotting were used to measure the changes in target biomarkers. Luciferase reporter assay was used to evaluate the interactions between miR-552 and PTEN. miRNA sequencing was used to check the changes in miRNA profiles. <b><i>Results:</i></b> miR-552 was upregulated in the laryngocarcinoma patients and was positively correlated to the cell proliferation and tumor growth. PTEN was identified as a direct target of miR-552. Hep-2 exosome is featured by high expression of miR-552 and treatment of Hep-2 exosome enhanced cell proliferation and tumorigenicity. The underlying mechanisms revealed that treatment of exosomes enhanced the malignant transformation of recipient cells in part by regulating epithelial-mesenchymal transition. <b><i>Conclusion:</i></b> Exosome miR-552 promotes laryngocarcinoma cells’ malignant progression in part by the regulation of the PTEN/TOB1 axis.