Heterogeneity of IL-15-expressing mesenchymal stromal cells controls natural killer cell development and immune cell homeostasis

Bone marrow stromal cells have been shown to not only provide bone tissue structure, but guide hematopoiesis and lymphocyte differentiation. The role of Interleukin 15 (IL-15) expression in BM stromal cells and potential implication on immune cell homeostasis remains unknown. Here, we generated an IL15-IRES-EGFP knockin reporter mouse model to define and study IL15-expressing BM stromal cells. We profiled non-hematopoietic IL-15 expressing bone and bone marrow stromal cells from IL15-IRES-EGFP reporter mice. We enriched stromal and endothelial cells from eight 7 individual IL15-IRES-EGFP mice at the age of 8-12 weeks by FACS (Aqua Zombie- CD45- Ter119- and CD31- IL15-GFP+ for MSCs and CD31+ IL15-GFP+ for endothelial cells) and profiled them by scRNA-seq (10xGenomics, 3' chemistry)