Cultured vascular endothelial cells secrete a protein factor(s) that promotes the contraction of collagen lattices made with fibroblasts.

Conditioned media collected from arterial endothelial cells contain protein factor(s) that promotes the contraction of collagen lattices made with skin fibroblasts. Based on the lattice contraction-promoting activity, a protein with an apparent molecular weight of 22 kDa was identified. This 22-kDa protein stimulated lattice contraction in both serum-containing and serum-free media. When assayed at a 30% equivalent of the conditioned medium, the contraction-promoting activity of the purified factor was about 50 to 60% of that elicited by the unfractionated conditioned medium. Some contraction-promoting activity was also present in certain subfractions of the conditioned medium generated during the separation of the 22-kDa protein. Taken together, the results indicate that the lattice contraction-promoting activity in the endothelial cell-conditioned medium is probably aided by multiple active principles. The biochemical and biological characteristics indicated that the 22-kDa protein is not a transforming growth factor-beta-related factor nor a fibroblast growth promoter.