BioProject

Endothelial cells cover the lining of different blood vessels and lymph nodes, and have major functions including the transport of blood, homeostasis, inflammatory responses, control of infiltration of circulating cells into the tissues, and formation of new blood vessels. More...

Endothelial cells cover the lining of different blood vessels and lymph nodes, and have major functions including the transport of blood, homeostasis, inflammatory responses, control of infiltration of circulating cells into the tissues, and formation of new blood vessels. Therefore, understanding these cells is of major interest. The morphological features, phenotype and function of endothelial cells varies according to the vascular bed examined. The sialomucin, CD34, is widely used as an endothelial marker. However, CD34 is differentially expressed on endothelial cells in different organs and in pathological conditions. Little is known about regulation of endothelial CD34 expression or function. This marker is also strongly modified in-vitro in endothelial cell models, including human umbilical vein endothelial cells (HUVEC) and endothelial progenitor cells (EPC). We have therefore selected CD34high and CD34low endothelial cell subpopulations and examined their CD34 expression and function. Results: Transcriptomic analysis showed that CD34 gene and protein expressions are highly correlated, that CD34high cells are less proliferative, and have a stronger expression of IL-33 and Angiopoietin 2, compared to CD34low cells. Higher secretion levels of IL-33 by CD34high HUVECs was confirmed by ELISA. Finally, when endothelial cells were allowed to interact with peripheral blood mononuclear cells (PBMCs), CD34high endothelial cells induced a stronger proliferation of regulatory T lymphocytes (Tregs) compared to CD34low cells whereas expansion of other CD4+-T cell subsets was equivalent. These results suggest that CD34 expression by endothelial cells in-vitro associates with their ability to proliferate and with an immunogenic ability that favours the tolerogenic response. Overall design: Gene expression analysis were performed on CD34high and CD34low endothelial colony-forming cells (ECFs). Less...