Differential expansion of human endothelial monolayers on basement membrane and interstitial collagens, laminin and fibronectin in vitro.

In this study the ability of a human endothelial cell monolayer to expand over specific components of the basement membrane and extracellular matrix was investigated over a 5-day period. The method was intended as a model to study the mechanisms of endothelial regeneration. All components were coated onto sterile coverslips at a concentration of 10 micrograms/ml. The highest expansion was obtained on fibronectin, laminin and collagen type III, all three being statistically significantly greater than on the uncoated control surface (0.002 greater than p greater than 0.0001). Collagens types I and IV and a high molecular weight fragment mixture of type IV (IV-F, consisting of 75, 120 and 140 kD fragments) elicited approximately similar expansion rates, significantly higher than the control (0.02 greater than p greater than 0.003), although significantly lower (approximately 15%) than collagen type III, fibronectin and laminin (p less than 0.001). The high monolayer expansion on collagen type III is surprising, as it is a relatively minor biosynthetic product of the endothelial cell. It could, however, be of significance in wound healing, in which endothelial cells come into contact with this interstitial collagen. In addition, the similar results obtained with collagens IV and IV-F indicate that expansion of the endothelial monolayer is not dependent on the integrity of the tetrameric structure of type-IV collagen.