5-アザシチジンはinvitroでヒト内耳細胞の有毛細胞マーカー発現を誘導する

Adult human inner ear hair cells have extremely limited regenerative ability, and the inaccessibility of human inner ear tissue makes studying regeneration challenging. In this study, we examined whether 5-azacytidine (5-aza) could induce hair cell-like differentiation using our previously established human utricular cell (HUC) line. Our results showed that treatment with 40-80 μM 5-aza was non-toxic, as confirmed by cell counting and calcein/propidium iodide assays. BrdU incorporation analysis showed that fewer treated HUCs entered the S-phase, indicating reduced cell proliferation following 5-aza treatment. Reverse transcription PCR revealed that 5-aza induced the expression of hair cell genes (Myo7a, Pou4f3, Atoh1, and Myo6), which were absent in untreated cells. Immunofluorescence confirmed the expression of hair cell proteins in 5-aza-treated cells, including Myosin VIIa, Pou4f3, Atoh1, Myosin VI, and Calretinin. Additionally, FM1-43 uptake assays indicated the emergence of functional mechanotransduction-like channels in 5-aza-treated HUCs. Together, these results demonstrate that 5-aza reduces proliferation and promotes differentiation of HUCs toward a hair cell-like phenotype. This finding provides new insight into the molecular mechanisms regulating human sensory hair cell differentiation in vitro and highlights the potential of HUCs as a model for studying human inner ear hair cell regeneration.