Quiescent horizontal basal stem cells act as a niche for olfactory neurogenesis in a 3D organoid model

The olfactory epithelium contains two basal stem cell populations that facilitate the normally life-long ability for neuronal regeneration that is required for maintaining our sense of smell over the long term. Horizontal basal cells (HBCs) are generally quiescent and only become active after direct injury to the epithelium that kills more than just the olfactory sensory neurons (OSNs). Globose basal cells (GBCs) lie apical to HBCs and are solely responsible for the ongoing generation of olfactory neurons in the undamaged epithelium. Understanding how these two neurogenic stem cell populations are regulated as OSNs are replenished is hampered by a lack of robust culture models. Here, we report the development of a 3-dimensional organoid model that recapitulates the neurogenic cascade while maintaining both HBCs and GBCs in culture. We use this model to demonstrate that despite their relative quiescence, HBCs form a critical niche for the emergence and composition of the organoid. Overall design: We grew mouse olfactory epithelial organoids from single-cell dissociated tissue and subjected them to Parse single-cell RNAseq to characterize the cells contained within these organoids. Libraries were constructed following kit instructions and then sequenced on a NovaSeq6000 before processing using the provided computational pipeline.