Endothelial cells from umbilical vein and a hemangioendothelioma secrete basement membrane largely to the exclusion of interstitial procollagens.
The biosynthesis of extracellular matrix proteins by primary cultures of endothelial cells from human umbilical vein, and by clones from a murine hemangioendothelioma, was studied and compared to that reported for endothelium cultured from other sources. Umbilical vein endothelial cells secreted two glycoproteins-fibronectin and thrombospondin-which comprise the major proportion of the protein in the culture media of bovine aortic, venous, and corneal endothelial cells. These biosynthetic products were absent from hemangioendothelioma cultures. However, in contrast to bovine endothelium from large vessels and cornea, which secrete primarily Type III procollagen into the culture medium, both the umbilical vein and hemangioendothelioma cultures secrete Type IV (basement membrane) procollagen. In addition, EC, a novel endothelial collagen type that has been characterized in bovine endothelial cell supernates, was not present in the umbilical vein or tumor-derived endothelium. The production of basement membrane procollagen as the major collagen type in the medium of these cultures probably reflects the nature of the vascular bed from which the endothelial cells originated, rather than differences in species of in cellular isolation and subculture. We suggest that endothelial cells from different vascular environments could display variations in growth, migration, morphology, and response to exogenous blood-borne factors as a result of their relationship to an extracellular matrix/subendothelium composed of diverse structural glycoproteins.