Mapping the developmental potential of mouse inner ear organoids at single-cell resolution
Inner ear organoids recapitulate development and are intended to generate cell types of the otic lineage for applications such as basic science research and cell replacement strategies. Here, we use single-cell sequencing to study the cellular heterogeneity of late-stage mouse inner ear organoid sensory epithelia, which we validated by comparison with data sets of the mouse cochlea and vestibular epithelia. We resolved supporting cell sub-types, cochlear like hair cells, and vestibular Type I and Type II like hair cells.  While cochlear like hair cells aligned best with an outer hair cell trajectory, vestibular like hair cells followed developmental trajectories similar to in vivo programs branching into Type II and then Type I extrastriolar hair cells. These results highlight the transcriptional accuracy of the organoid developmental program but will also inform future strategies to improve synaptic connectivity and regional specification. Overall design: Examination of transcriptional profiles of inner ear organoids at 16, 20, and 21 days-in-vitro (DIV). Samples prepared at 21 DIV were divided into GFP high and GFP low groups.