Diseases like COPD, bronchitis, and asthma implicate the mucociliary epithelium in their pathology. This tissue helps move mucus to the pharynx away from the lungs and consists of a variety of cell types including mucus-producing goblet cells, stem cells, and multiciliated cells. All of these cell types work together to coordinate the function of the tissue; the failure of any one of these cell types can lead to a diseased airway.
The ciliated epithelium is present in different regions of the body: the brain, the airway, and the oviducts. Ciliated cell specification starts with in the sensorial layer before they intercalate between the mucus-producing cells in the outside layer. Natarajan pointed out that the course of the other cell types during this process still remains unclear.
Those other cells in question are the mucus-secreting goblet cells and ionocytes, and basal cells which are late stage stem cells. Natarajan explained that work on single cell atlases have shown that research on this tissue in mice does not translate to lower vertebrates and humans.
And so, Natarajan’s team set out to Chart the developmental mucociliary epithelium morphogenesis at a single cell level; Chart cell fate paradigms in the developing tissue; and conduct an evolutionary developmental comparison across species.
Natarajan's group conducted single cell RNA sequencing across multiple developmental stages of frog embryos to chart the morphogenesis of mucociliary epithelium. The results reveal that different cell types emerge through complex developmental pathways, challenging existing paradigms of cell type specification.
The analysis identified a new cell type termed early epithelial progenitors, which exhibit a flexible state of differentiation before committing to specific cell lineages. This finding supports the notion that cell development is a continuous and non-hierarchical process rather than a discrete series of stages.
