Urokinase Receptor Regulates Adhesion of Progenitor Cardiac Cells to Vitronectin

Vitronectin, extracellular matrix protein, plays an important role in embryonic development and in organ and tissue reparation. A unique characteristic of vitronectin is specific binding of various biological molecules, including urokinase receptor (uPAR), extracellular matrix components, adhesion receptors, growth factors, thus supporting the modulation of cell behavior. Vitronectin is in fact not found in intact myocardium, while after infarction its level increases significantly, which correlates with accumulation of uPAR⁺ progenitor cardiac cells in the focus. The cells isolated from the heart of wild type mice are characterized by higher adhesion to vitronectin than progenitor cardiac cells from the myocardium of uPAR knockout mice. In addition, inhibition of urokinase receptor with specific antibodies on the surface of the progenitor cardiac cells of wild type mice leads to attenuation of their adhesive activity and flattening on vitronectin matrix, which can be important for their distribution in the postinfarction myocardium and realization of the reparative functions.