Two-stage isolation procedure for obtaining homogenous populations of microvascular endothelial and mesothelial cells from human omentum.

The human omentum is a highly vascularized tissue often advocated as a source of human microvascular endothelial (HOME) cells. The omentum also contains mesothelial (MESO) cells and isolation protocols published to date do not describe a separation of the two cell populations. Using a two-stage collagenase digestion procedure, homogenous populations of HOME and MESO cells are obtained from the same omental tissue sample. HOME and MESO cells are both simple squamous epithelial cells and consequently are often difficult to discriminate between based on morphology and reactivity with many of the conventional endothelial and mesothelial cell markers. Both HOME and MESO cells form typical cobblestone, contact-inhibited monolayers, metabolize DiI-Ac-LDL, and are immunoreactive to von Willebrand Factor and Ulex europeaus I lectin. However, MESO cells are distinguishable from HOME cells based upon their expression of cytokeratins. Moreover, HOME cells and not MESO cells form capillary-like structures when cultured on Matrigel. It appears that HOME and MESO cells share many phenotypic properties, but are distinguishable from one another based upon a comprehensive panel of endothelial and mesothelial markers. Both cell types should be useful for studying the biology and pathology of the human microvasculature in vitro.