Human omental microvascular endothelial and mesothelial cells: characterization of two distinct mesodermally derived epithelial cells.

Human omental microvascular endothelial (HOME) and mesothelial (MESO) cells share many phenotypic properties, but can be characterized from one another based upon a comprehensive panel of endothelial and mesothelial markers. Traditional cell markers such as von-Willebrand factor, DiI-Ac-LDL, and Ulex europaeus I lectin are not sufficient to distinguish between HOME and MESO cells. Furthermore, immunoreactivity to a panel of endothelial cell-specific monoclonal antibodies, including representatives from the known clusters of differentiation (CD), indicate that some of these antigens are coexpressed in HOME and MESO cells. In distinguishing between the two cell types, HOME and not MESO cells express E-selectin, E/P-selectin, P-selectin (CD62), Le-y, and VLA-6 (CDw49f*). Moreover, HOME cells and not MESO cells form tube-like structures when cultured on Matrigel. MESO cells differ from HOME cells based upon (1) the expression of cytokeratins; (2) their rapid proliferation in response to platelet-derived growth factor; and (3) a change from an epitheliod to fibroblast-like morphology in response to tumor necrosis factor and epidermal growth factor. Both HOME and MESO cells express tissue plasminogen activator and plasminogen activator inhibitor, but urokinase activity is only expressed by MESO cells. As there is no one universal endothelial or mesothelial cell marker that can specifically confirm the identity of these cells, it appears necessary to employ a comprehensive panel of cell markers to rule out the possibility of misidentifying a cell culture.