Human microvessel endothelial cells: isolation, culture and characterization.

Over recent years, interest in endothelial cell biology has increased dramatically with our ability to grow and study endothelial cells in vitro. While large veins and arteries remain a quick and convenient source of endothelial cells, the great morphological, biochemical and functional heterogeneity that endothelial cells express has necessitated the development of techniques to isolate microvessel endothelial cells from different tissues to create more realistic in vitro models. The majority of isolation procedures employ selective methods to enrich microvessel endothelial cells from tissue homogenates directly, or after a period in culture. These include sieving/filtration, manual weeding, isopycnic centrifugation, selective growth media, and the use of flow cytometry or magnetic beads coupled with specific endothelial cell markers. The establishment of pure endothelial cell populations is important for studying their biochemistry and physiology and there are many morphological, immunological and biochemical criteria which can be used to characterize human endothelial cells. These range from classical markers such as von Willebrand Factor and angiotensin-converting enzyme to novel markers like platelet endothelial cell adhesion molecule-1 (CD31) and the expression of E-selectin on cytokine-activated endothelial cells.