Microvascular endothelial cells from human omental tissue: modified method for long-term cultivation and new aspects of characterization.

A method for long-term cultivation of large amounts of human microvascular endothelial cells from the omental tissue (human omental tissue microvascular endothelial cells, HOTMECs) was devised. The method originally described by Kern, Knedler, and Eckel was modified: HOTMECs were isolated by enzymatic dissociation with collagenase. For primary cultivation and passages, HOTMECs were plated either onto fibronectin-coated petri dishes or onto a human fibroblast extracellular matrix (HFB-ECM) prepared from the same tissue. Omental tissue (10-15 g) yielded 4-8 X 10(5) HOTMECs; more than 90% of the cells adhered to precoated dishes and grew in Waymouth's culture medium supplemented with 20% heat-inactivated fetal calf serum. Confluence was reached 3-5 days after seeding with an average of 1-2 X 10(6) cells/dish. Confluent HOTMEC layers were subcultured at a split ratio of 1:3 up to 11 passages by plating the cells onto dishes coated with HFB-ECM and maintained in long-term culture for up to 3 months. The endothelial origin of these cells was demonstrated as follows. The cells in culture showed the typical "cobblestone" growth pattern and synthesized von Willebrand factor (vWF) as determined by metabolic labeling. Using an indirect immunostaining technique, the cytoplasm of the HOTMECs stained for vWF. A monoclonal antibody specific for human endothelial cells bound exclusively to the cultured cells. The expression of thrombomodulin on the surface of the cultured cells was demonstrated by the activation of protein C by thrombin. In control experiments, these features could be detected on neither fibroblasts nor mesothelial cells.