Heterogeneity of Endothelial Cells

Abstract

During embryonic development, endothelial cells differentiate from a common precursor called angioblast and acquire organ-specific properties. One of the important determinants of endothelial cell differentiation is the local environment, and especially the interaction with surrounding cells. This interaction may occur through the release of soluble cytokines, cell-to-cell adhesion and communication, and the synthesis of matrix proteins on which the endothelium adheres and grows. The acquisition and maintenance of specialized properties by endothelial cells is important in the functional homeostasis of the different organs. For instance, in the brain, alteration of the blood-brain barrier properties may have important consequences on brain functional integrity. One of the major limitations to the study of endothelial cell heterogeneity is the fact that these cells are still difficult to isolate and culture from the microcirculation of different organs, and once in culture, they tend to lose their specialized properties. This finding suggests that we have to develop new culture systems, which possibly include coculture with other cell types. An important issue is to develop tools that can help in recognizing endothelial cells and their differentiated phenotype both in vivo and in tissue culture. In this review we give a short overview of the differentiated properties of the endothelium, considering a few examples of highly specialized endothelial cells, such as the brain or bone marrow microcirculation or high endothelial venules. We made a particular effort to list the most common markers of endothelial cell phenotypes. These molecules and related antibodies may be valuable tools for endothelial cell isolation and characterization.

Flow Cytometry in Preclinical Toxicology/Safety Assessment

“…Differential immunophenotyping results led to the hypothesis that rat CECs/CEPs are a complex mixture that may include cells that are in different states of maturation or differentiation, originate from different sites, and/or are of hematopoietic and nonhematopoietic origin. This agrees well with published data describing many differences in growth, morphology, structural organization, protein expression, and function in endothelial cells from various sources throughout the vasculature [18,21].…”

Characterisation of glucose transporters in the intact coronary artery endothelium in rats: GLUT-2 upregulated by long-term hyperglycaemia

“…We observed a downregulation of GLUT-1, 3, 4, and 5, and a three-fold increase of GLUT-2 in the endothelial cells of STZ-diabetic rats. We examined an en face endothelial preparation because endothelial cell structure is maintained by the surrounding environment and by interactions with neighbouring cells [10,28]. In particular, endothelial cells, when cultured, have a tendency to lose the ability to express most of the GLUT and SGLT isoforms [29,30].…”

“…The integrity of endothelial cells of small contractile vessels is also affected by hyperglycaemia, and the coronary arteries are among the most susceptible to atheroma, but few studies have directly examined glucose transporters in these vessels [6]. Despite having the same embryonic origin, there is a strong heterogeneity between endothelial cells of different vascular beds, and even those within the same vascular bed are known to have morphological, physiological and biochemical differences [10,11]. Data derived from one vascular bed may not be applicable to the rest of the vasculature.…”

Involvement of bone marrow-derived stem and progenitor cells in the pathogenesis of pterygium

“…Leucocyte antigen CD34 is the common surface marker for the haematopoietic progenitor cells and endothelium, 11 and it appears early in development as an endothelial cell surface receptor. 12 The c-Kit protooncogene has been identified as a member of the receptor-tyrosine kinase family. When the c-Kit receptor binds with human stem cell factor (SCF), also termed cKit ligand, which is produced by mesenchymal cells, it will augment the proliferation of primitive bone marrow progenitor cells and differentiated mast cells.…”