Plasma fibronectin is sequestered into tissue damaged by inflammation and trauma

Mechanical trauma or inflammatory reaction induced in striated muscle tissue of rats was followed by a flux of fibronectin from plasma into the damaged tissue, as determined by measurement of radioactivity, autoradiography and immunofluorescence. When homogenized muscle tissue was incubated with labelled fibronectin prior to separation of its subcellular components by ultracentrifugation, fibronectin bound to all fractions, but with strongest affinity for the microsomal and plasma membrane fraction. When trauma occurs, fibronectin from plasma binds to exposed structures on cell membranes and to components of connective tissue such as collagen and proteoglycans. Because of its ability to mediate cellular adhesion to tissue components, fibronectin probably exerts important functions in normal wound healing.