GSE185669
Developmental dynamics of the neural crest-mesenchymal axis in creating the thymic microenvironment
The thymic stroma is composed of epithelial and non-epithelial cells that collectively provide separate microenvironment controlling the homing of blood-born precursors to the tissue, and their subsequent differentiation to functionally mature and correctly selected T cells. While thymic epithelial cells are well characterised for their role in thymopoiesis, a comparably comprehensive analysis of the non-epithelial thymic stroma is lacking. Here we explore at single cell resolution the complex composition and dynamic changes that occur over time in the non-epithelial stromal compartmenti. We detail across different developmental stages in human and mouse thymus tissues and in an experimental model of the most common form of human thymus hypoplasia the separate transcriptomes of mouse mesothelium, fibroblasts, neural crest cells, endothelial and vascular mural cells. The detected gene expression signatures identify novel stromal subtypes and relate their individual molecular profiles to separate differentiation trajectories and functions. Specifically, we demonstrate an abundance and unprecedented heterogeneity of diverse fibroblast subtypes that emerge at discrete developmental stages and vary in their expression of key regulatory signalling circuits and components of the extracellular matrix. Taken together, these findings highlight the dynamic complexity of the non-epithelial thymus stroma and link the cells' specific gene expression profiles to separate instructive roles essential for normal thymus organogenesis and tissue maintenance. The study has been granted ethical approval and is publicly listed (IRAS ID 156910, CPMS 19587). Overall design: Human thymic stromal cells - 10x Genomics multiomics (gene expression [GEX] and Assay for Transposase-Accessible Chromatin [ATAC]): 14 post-conceptional weeks (n=1) and 17 post-conceptional weeks (n=1)