Inner ear organoids: Recent progress and potential applications

The inner ear is one of the most complicated structures that harbor organs for the perception of sound and balance, which is deep in the temporal bone and challenging to operate. Organoids serve as promising platforms for understanding developmental processes and pathological dysfunctions and discovering therapeutic drugs and gene therapy strategies for disorders in the inner ear. To better understand the origin and application value of organoids, we reviewed the developmental history and advancement of inner ear organoid research. We summarized the cell sources of organoids and the matrices supporting their formation. The history of the research on inner ear organoids derived from pluripotent stem cells (PSCs) and primary progenitor cells has been clarified in detail. We elaborated on the applications of organoids in inner ear development, hereditary deafness modeling, and hair cell (HC) regeneration strategy formulation. Finally, we mentioned limitations of the current culture methods and applications of inner ear organoids, and described several prospects for optimizing next-generation organoids of the inner ear for potential translational applications.