Integration of single-cell transcriptomes and biological function reveals distinct behavioral patterns in bone marrow endothelial cells [bulk RNA-seq]

Heterogeneity of endothelial cell populations reflects their diverse functions in maintaining tissue’s homeostasis. However, their phenotypic, molecular, and functional properties are not entirely mapped. We used a new Tie2-CreERT2;Rosa26-tdTomato reporter mouse to trace, profile, and cultivated primary ECs from different organs. As platform paradigm, we used this strategy to study bone marrow endothelial cells (BMEC). Single-cell mRNA sequencing of primary BMEC revealed that their diversity and native molecular signatures is transitorily preserved in an ex-vivo culture that conserves key cell-to-cell microenvironment interactions. Macrophages sustained primary BMEC cellular diversity and expansion and were critical to preserve sinusoidal-like BMEC ex-vivo. Expression of endomucin discriminated BMEC in populations exhibiting mutually exclusive properties and distinct tip and stalk signatures. In contrast to arterial-like, sinusoidal-like BMECs were short-lived, formed 2D-networks, contributed to in-vivo angiogenesis and supported hematopoietic stem/progenitor cells in-vitro. This platform can be extended to other organs’ ECs to decode mechanistic information and explore therapeutics. Single-cell mRNA sequencing of primary BMEC cultures and bulk sequencing of Emcn+ and Emcn- BMEC sorted from P0 WBM, cultured MSC and lung.