ABSTRACT This research proposal focuses on the complex development of inner ear cells from various embryonic lineages and the challenges of establishing multi-lineage inner ear tissues in vitro. The inability to routinely utilize patient-derived inner ear explants due to their delicate nature prompts a necessity for a unique approach. Thus, the project's long-term objective is to uncover the chemical and physical signals required to cultivate functional inner ear tissue from human pluripotent stem cells (hPSCs) in vitro. Building on past technological advancements, the research will refine a three-stage 3D culture system to create inner ear organoids (IEOs) – a model that successfully generates sensory hair cells, neurons, glia, and mesenchymal cells. The project seeks to overcome current limitations of IEO heterogeneity and free-floating nature, which restrict live-cell imaging applications essential for advancing drug discovery and gene therapy testing. The primary goal is to develop a standardized, reproducible IEO-on-a-chip system that mirrors the human fetal inner ear, comprising sensory epithelia, peri-otic mesenchyme, and neural inputs. The project has three specific goals: 1) refine the production and purification of otic organoid cellular components, 2) decipher the physio-chemical needs for on-chip otic morphogenesis, and 3) establish image-based assays to investigate hair cell function and dysfunction in IEOs-on-chip. We intend to use genomic data from every stage of IEO development and leverage cell-cell communication analysis to enhance otic cell production. Next, we aim to engineer an on-chip microenvironment promoting self-assembly of tubular otic sensory epithelia. Finally, the study plans to establish image-based assays for on-chip assessment of genetic perturbation to hair cell functional maturation using models related to the deafness-blindness disorder Usher Type 1. The successful completion of this project would lead to a first-of-its-kind tissue chip for inner ear research, offering significant value in the development of innovative gene therapies, as well as protective and regenerative drugs. The proposed system shows potential in addressing current research challenges and spurring advancements in understanding and treating hearing and balance-related diseases.