# Inducible Hair Cell Degeneration in Human Inner Ear Organoids

> **NIH NIH R21** · INDIANA UNIVERSITY INDIANAPOLIS · 2021 · $237,750

## Abstract

PROJECT SUMMARY
Loss of sensory hair cells in the inner ear causes irreversible hearing loss in humans. Currently there is no
scalable human model system to test pharmacological treatment options for promoting biological restoration of
hearing. My laboratory recently developed a novel human inner ear organoid system to generate inner ear
sensory epithelia containing functional sensory hair cells from aggregates of human pluripotent stem cells in
3D culture. Although this system is valuable for recapitulating human inner ear development, a human in vitro
model of hair cell degeneration is needed for studying hair cell regeneration. We propose to use the inducible
Caspase 9 (iCaspase9) genetic “suicide switch” approach to selectively, rapidly and synchronously ablate hair
cells in human inner ear organoids. This system is based on the fusion of human Caspase 9 to a modified
human FK-binding protein, allowing for conditional dimerization using a small molecule compound. In Aim 1,
we will establish and validate human BRN3C-iCaspase9-tdTomato (BRN3C-iCT) organoids in which sensory
hair cells are fluorescently visualized and promptly ablated upon treatment with the dimerizer AP20187.
The validated knock-in human embryonic stem cells will then be differentiated into inner ear organoids. After
confirmation of hair cell development, AP20187 will be added to culture medium to trigger selective
degeneration of sensory hair cells through activation of endogenous Caspase 3. In Aim 2, single-cell RNA-
seq will be carried out to detect transcriptional changes in human stem cell-derived sensory hair cells and
supporting cells in response to Caspase 9 dimerization. The outcome of this study will provide a paradigm-
changing approach for developing and testing chemical compounds capable of promoting hair cell
regeneration, and consequently restoring hearing, in individuals with hearing impairments.

## Key facts

- **NIH application ID:** 10127618
- **Project number:** 5R21DC018643-02
- **Recipient organization:** INDIANA UNIVERSITY INDIANAPOLIS
- **Principal Investigator:** Eri Hashino
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $237,750
- **Award type:** 5
- **Project period:** 2020-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10127618

## Citation

> US National Institutes of Health, RePORTER application 10127618, Inducible Hair Cell Degeneration in Human Inner Ear Organoids (5R21DC018643-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10127618. Licensed CC0.

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