Stem cell - based therapies for auditory hair cell regeneration and treatment of hearing loss.

The incidence and prevalence of hearing loss is increasing globally at an accelerated pace. Hair cells represent the sensory receptors of auditory and vestibular systems. Hair cell absence, loss or degeneration due to congenital diseases, trauma, toxicity, infection or advancing age, results in disabling hearing loss. Regenerative medicine (RM) approaches consisting in stem cell-based hair cell rescue or regeneration, gene therapy as well as cell and tissue engineering are expected to dramatically improve the therapeutic arsenal available for addressing hearing loss. Current strategies that are using different stem cell types in order to rescue or to induce hair cell proliferation and regeneration are presented. Gene and cell therapy methods that modulates trans differentiation of surrounding cell types into hair cells are presented, together with their specific advantages and limitations. Several modalities for improving therapeutic targeting to the inner ear such as nanoparticle mediated cell and gene delivery are introduced. Further steps in building more relevant high throughput models for testing novel drugs and advanced therapies are proposed as a modality to accelerate translation to clinical settings.