Stem cell-based strategies for hearing restoration: Current advances and future perspectives

Figure 1 Cochlear functional unit and therapeutic targets for hearing restoration. The upper panel illustrates the cross-sectional anatomy of the organ of Corti, highlighting that hearing restoration requires the integrated reconstruction of a multicellular unit rather than a single cell type. Key targets include hair cells (mechanoelectrical transduction), supporting cells (structural support and regenerative competence), spiral ganglion neurons (auditory signal relay), ribbon synapses (sensory-neural connectivity), and the stria vascularis/Lateral wall (ionic homeostasis and metabolic support). The lower panel summarizes three major stem cell-based therapeutic paradigms: Exogenous cell replacement utilizing pluripotent stem cells (module 1); endogenous progenitor activation and supporting-cell reprogramming (module 2); and cell-free repair mediated by stem cell-derived extracellular vesicles for niche modulation (module 3). IHC: Inner hair cell; OHC: Outer hair cell; PSCs: Pluripotent stem cells; SGN: Spiral ganglion neuron; EV: Extracellular vesicle.