Fibroblast growth factor-2 did not restore plasminogen system activity in endothelial cells on glycated collagen

People with diabetes experience morbidity and mortality from unregulated microvascular remodeling, which may be linked to hyperglycemia. Elevated glucose leads to extracellular matrix collagen glycation, which delays endothelial capillary-like tube formation in vitro. Glucose also increases endothelial cell fibroblast growth factor-2 (FGF-2) release and extracellular matrix storage, which should increase tube formation. In this study, we determined if FGF-2 could restore plasminogen system activity and angiogenic function in endothelial cells on glycated collagen. Human umbilical vein endothelial cells cultured on native or glycated collagen substrates were stimulated with FGF-2. Plasminogen system activity, cell migration, and capillary-like tube formation were measured, along with plasminogen system protein and mRNA levels. Glycated collagen decreased endothelial cell plasminogen system activity, cell migration, and tube length. FGF-2 did not restore plasminogen system activity or tube formation in cells on glycated collagen, despite decreasing plasminogen activator inhibitor-1 (PAI-1) protein level. We now show that PAI-1 binds to glycated collagen, which may localize PAI-1 to the extracellular matrix. These data suggest that FGF-2 may not restore angiogenic functions in endothelial cells on glycated collagen due to PAI-1 bound to glycated collagen.