[The effect of fibronectin fragments on proliferative activity of fibroblasts]

The effects of fibronectin and fragments of its limited proteolysis by plasmin on the proliferative activity of human embryo fibroblasts in culture were studied. It was found that native fibronectin and its fragments with Mr greater than or equal to 120 kD do not exert either a stimulating or inhibiting influence, whereas the 15-43 kD fragments significantly stimulate cell proliferation. The stimulating effect increases with a rise in the fragment concentration, reaching a maximum at 12-25 micrograms/ml and decreases at their higher concentrations. The preparation of proliferation-stimulating fragments contains no proteinases admixtures that are active at neutral pH and does not possess any intrinsic proteolytic activity. The proliferation-stimulating activity does not change after removal of collagen-binding fragments.