Abstract
Stem cell-derived inner ear sensory epithelia are a promising source of tissues for treating patients with hearing loss and dizziness. We recently demonstrated how to generate inner ear sensory epithelia, designated as inner ear organoids, from mouse embryonic stem cells (ESCs) in a self-organizing 3D culture. Here we improve the efficiency of this culture system by elucidating how Wnt signaling activity can drive the induction of otic tissue. We found that a carefully timed treatment with the potent Wnt agonist CHIR99021 promotes induction of otic vesicles—a process that was previously self-organized by unknown mechanisms. The resulting otic-like vesicles have a larger lumen size and contain a greater number of Pax8/Pax2-positive otic progenitor cells than organoids derived without the Wnt agonist. Additionally, these otic-like vesicles give rise to large inner ear organoids with hair cells whose morphological, biochemical and functional properties are indistinguishable from those of vestibular hair cells in the postnatal mouse inner ear. We conclude that Wnt signaling plays a similar role during inner ear organoid formation as it does during inner ear development in the embryo.
Highlights
The sensory organs of the inner ear—the macula, cristae, and the Organ of Corti—develop from a symphony of complex spatiotemporal signaling mechanisms
To evaluate the reproducibility of our inner ear induction protocol [1, 24], we applied it to several different mouse pluripotent stem cell lines, including wild-type R1 [21], wild-type R1/E, Atoh1/nGFP [22] embryonic stem cells (ESCs) and Oct4/eGFP induced pluripotent stem cell (iPSC) [23]
Aggregates from all stem cell lines grew at a similar rate and generated outer-epithelia that thickened following treatment with BMP4 and the TGFβ inhibitor SB-431542 at day 3 followed by FGF2 and the bone morphogenetic protein (BMP) inhibitor LDN-193189 at day 4–4.5 (Fig 1A’–1D’ and 1E–1H)
Summary
The sensory organs of the inner ear—the macula, cristae, and the Organ of Corti—develop from a symphony of complex spatiotemporal signaling mechanisms. These sensory organs allow for the detection of linear acceleration due to gravity, angular acceleration, and transduction of sound waves into nerve impulses. We previously reported that inner ear sensory epithelia could be generated from mouse pluripotent stem cells over a period of 14–20 days in 3D culture [1]. We first generated a non-neural epithelium and induced an otic epibranchial pre-placodal epithelium by inhibiting bone morphogenetic protein (BMP) and activating fibroblast growth factor (FGF) signaling. A critical step in the latter process is the self-organized formation of otic vesicles within the cell aggregates.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
