Two cloned cerebral endothelial cell phenotypes: an in vitro model for angiogenesis?

Expression of smooth muscle alpha-actin and migratory behaviour of cloned cerebral endothelial cells (cEC) which exhibited two distinct phenotypes (type I, type II) were studied. Removal of mitogenic factors (alpha ECGF, ECGS) and heparin from the culture medium resulted in a smooth muscle-like appearance (type II) of the cells, expression of smooth muscle alpha-actin protein and smooth muscle actin mRNA and in an increased migratory activity. In contrast, addition of growth factors and heparin led to a cobblestone-like phenotype (type I) which lacked the expression of smooth muscle alpha-actin but expressed other proteins as determined by 2-D-gel electrophoresis.