Glycation of proteins of the vessel wall is thought to play an important role in the pathogenesis of vascular complications in diabetes by affecting structure and function of these proteins. Adhesive proteins in the extracellular matrix (ECM) of endothelial cells (ECs) are essential for attachment of ECs to the subintima. In this study, we investigated the effect of glycation of ECM and purified adhesive proteins on EC adhesion and spreading. ECM was incubated with the reactive sugar glucose-6-phosphate (0-500 mmol/l) for different time periods (0-14 days) at 37 degrees C. Degree of glycation, measured in an enzyme-linked immunosorbent assay using a monoclonal antibody specific for advanced glycation end products, increased in a time- and concentration-dependent manner. Glycation of ECM with 50 mmol/l glucose-6-phosphate resulted in increased coverage by ECs as measured in a cell adhesion assay and was the result of an increase in number of adhered cells, while cell size was unaffected. Glycation of ECM with higher concentrations of glucose-6-phosphate resulted in decreased coverage by ECs caused by both a reduction in number of adhered ECs and impaired spreading. Experiments with purified glycated matrix proteins indicate that the decrease in EC adhesion and spreading on glycated ECM may result from glycation of vitronectin. Impaired EC adhesion and spreading caused by vitronectin glycation may result in impaired endothelial function and contribute to vascular disease.