Migration of endothelial cells plays an important role during angiogenesis and the late remodeling phase of arteriogenesis. To investigate mechanisms responsible for cell migration, the authors subcloned a rat heart endothelial cell line (RHE) into a migrating and a nonmigrating cell line (RHE-A and RHE-neg, respectively). Both cell lines form cobblestone patterns in confluent cultures similar to the originating cell line, but RHE-neg cells grow in dense cell islets of several layers whereas RHE-A cells grow in a less dense monolayer. Both cell lines show the same expression pattern of known endothelial cell surface antigens (e.g., FIK-1). The authors used two-dimensional gel electrophoresis technique to look for differentially regulated proteins with possible functional importance for cell migration. The analysis of the cytosolic fraction as well as the membrane fraction revealed differences in the protein expression patterns of RHE-neg and RHE-A cells. Regulated spots were isolated and analyzed by mass spectrometry (MS/MS technique), leading to the identification of proteins potentially responsible for endothelial cell migration, e.g., the intermediate filament vimentin that was exclusively expressed in RHE-A cells. The authors thus have generated a reproducible model that allows the analysis of the proteome responsible for endothelial cell migration.
