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Description

During development, the otic vesicle (which forms the inner ear) and epibranchial neurons (which form the distal ganglia of cranial nerves) both originate from the otic-epibranchial progenitor domain (OEPD). In vitro, OEPD cells can be induced by the sequential exposure of mouse embryonic stem cells (mESCs) to bone morphogenic protein (BMP) and fibroblast growth factor (FGF) signaling in the inner ear organoid model. From there, activated Wnt signaling induces the otic fate over epibranchial. Analysis of inner ear organoids using single cell RNA-sequencing shows that OEPD and epibranchial cells are present prior to Wnt activation at 8 days in vitro (DIV). Further analysis of active signaling in DIV8 organoids revealed substantial BMP signaling to the OEPD from residual mESCs, as well as developing surface ectoderm and mesendoderm cells. Previous literature has shown that BMP signaling is important for epibranchial neuron development from the OEPD; in mice, BMP inhibition with the chemical LDN193189 can result in decreased epibranchial neuroblast formation. Based on these observations, we hypothesized that repression of BMP signaling could improve the formation of otic cells over epibranchial neurons. To test this, we added LDN193189 to DIV8 organoids and collected them on DIV11 at the stage of otic vesicle formation. Using qPCR, we found that LDN193189 treatment did not significantly change otic vesicle or epibrachial neuron marker gene expression compared to controls. Our results suggest that BMP inhibition at DIV8 may be too late of an intervention to have a significant effect on epibranchial neuron formation from the OEPD.

Publication Date

4-30-2026

Keywords

Differentiation, signaling, otic

Investigating the Effect of BMP Inhibition on Otic Vesicle vs. Epibranchial Neuron Formation in Inner Ear Organoids

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