Modeling Genetic Inner Ear Disorders with Human Pluripotent Stem Cells

The primary goal of this subcontract is to investigate the structure and the function of the sensory hair cells derived from human pluripotent stem cells in 3D culture. The major hypothesis postulates that, using proper developmental signaling, it is possible to generate not only mechanosensitive hair cell-like cells but also the cells that carry molecular, structural, and functional signatures of the auditory inner and outer hair cells. Specifically, we will perform the following studies: • We will explore the development of mechanotransduction responses and voltage-gated conductances in the hair cell-like cells of the human inner ear organoids; • In parallel, we will investigate the structure of stereocilia bundles in these hair cells using high resolution scanning electron microscopy (SEM); • In a separate set of experiments, we will explore the development of the actin core of stereocilia using serial sectioning with Focused Ion Beam and subsequent imaging with backscattered SEM (FIB-SEM); • We will determine whether the hair cell-like cells in the human inner ear organoids acquire functional electromotility by recording non-linear (voltage-dependent) capacitance that is characteristic of the cochlear outer hair cells; • In parallel experiments, we will explore whether acquisition of electromotility is accompanied with characteristic changes in the cytoskeleton at the lateral wall of the hair cells, such as formation of the closely apposed cortical cytoskeleton and the flattened layers of endoplasmic reticulum (subsurface cisternae). To avoid multiple artefacts of “classical” EM, we’ll utilize high-pressure freezing and freeze-substitution for sample preparation whenever it's possible.