Abstract: Hearing and balance disorders disable nearly half a billion people worldwide, yet there are virtually no pharmacological or biological therapies for these disorders. This alarming state of medicine coexist with the brighter state of science where numerous therapeutic approaches have shown efficacy in animal models. This conundrum reflects the fact that there are important differences between animal models and humans, that we have an incomplete understanding of the molecular signatures of the auditory and vestibular organs in the human inner ear, and that adult human inner ear tissues are not readily available to test promising therapeutics. We propose to solve this conundrum by defining the molecular makeup of normal, live human inner ear tissues (Aim 1), describing the three-dimensional (3D) cellular architecture of unprocessed human inner ears (Aim 2), training new and established investigators (Aim 3), and enhancing awareness of human inner ear research (Aim 4). In support of this approach, we have designed a surgical method to procure live inner ear tissues from deceased organ donors who typically have normal auditory and vestibular function. We have begun assembling a registry consisting of medical records, single-cell transcriptomes, and histologic sections of vestibular tissues (utricles). In parallel, we have augmented the registry with utricles from vestibular schwannoma patients undergoing surgical resection. Here, we propose to increase the recruitment of organ donors and vestibular schwannoma patients and expand our registry to include all inner ear sensory organs and generate a molecular cell atlas of the adult human inner ear (Aim 1). Additional tissues and perilymph will be collected, analyzed and shared with the broader scientific community for gene and protein validation. Furthermore, we will use a miniature, flexible imaging probe we developed to perform micro-optical coherence tomography (µOCT)-based endomicroscopy on rapid autopsy cadavers to generate an optical cell atlas of the 3D-intact, unprocessed human inner ear (Aim 2). A second registry will be assembled, consisting of digitized µOCT-histology images analyzed with the aid of both linear regression and artificial intelligence tools. Thirdly, we will train clinicians, clinician- scientists, and researchers on the techniques of procuring and imaging human inner ear tissues through hands- on training, simulated surgery, and didactic workshops (Aim 3). Lastly, we will raise awareness of studying human inner ear tissues through outreach activities, publicizing our resources, data sharing, and collaborations (Aim 4). Upon completion of this 5-year program, we will have assembled and shared a molecular and optical cell atlas of the human inner ear and increased awareness and utilization of this resource by the scientific community.

Narrative: Our program aims to build a molecular and optical cell atlas of the human inner ear as a resource for the scientific community to accelerate progress in discovering effective therapies for auditory and vestibular disorders. To achieve this objective, we will apply the latest molecular and optical imaging tools to live human inner ear tissues from organ donors, vestibular schwannoma patients, and rapid autopsy participants. We will also raise awareness of human inner ear research and enhance opportunities for collaboration by making our data and tissues widely available, by providing technical instruction, and by outreach activities.