Studies of morphologically atypical ("sprouting") cultures of bovine aortic endothelial cells. Growth characteristics and connective tissue protein synthesis.

Morphologic and biochemical studies were performed on cultures of bovine aortic endothelial cells which had developed a second growth pattern that has been referred to as "sprouting" (Gospodarowicz and Mecher, '78; Schwartz '78). These morphologically atypical cells undergrew the intact endothelial cell monolayer and appeared only after the cells had reached confluence. They were ultrastructurally very similar to endothelial cells, but synthesized reduced amounts of fibronectin and a predominance of type I procollagen, rather than the types III and IV procollagens synthesized by monolayer endothelial cells. It is suggested that these cells represent phenotypically altered endothelial cells that differ in biosynthesis of secreted proteins and display a reduced contact-inhibition.