Matrix-fibrinogen enhances wound closure by increasing both cell proliferation and migration

Fibrinogen (FBG) assembles into matrix fibrils of fibroblasts, lung and mammary epithelial cells, but not endothelial cells. Furthermore, cryptic beta(15-21) residues are exposed in FBG fibrils with no evidence of thrombin or plasmin proteolysis. Herein, the effects of FBG on migration and proliferation of wounded dermal fibroblasts were investigated. FBG preassembled into matrix prior to scrape-wounding induced H-3-thymidine incorporation 8-fold and shortened the time to wound closure 1.6-fold+/-0.1-fold. FBG added immediately after wounding did not enhance either response. Fibroblast growth factor-2/platelet-derived growth factor (FGF-2/PDGF) stimulated cell proliferation 2.2-fold for FGF-2 and 3.2-fold for PDGF and wound closure 1.5-fold+/-0.1-fold in the absence of matrix-FBG. Surprisingly, exogenous growth factors had negligible effect on wound closure and cell proliferation already enhanced by matrix-FBG. Matrix-FBG-enhanced wound closure required active assembly of an FBG-fibronectin matrix, engagement of alphavbeta3, and FBG Aalpha-RGDS(572-575) integrin recognition sites; Aalpha-RGDF(95-98) sites were not sufficient for matrix-FBG assembly, enhanced wound closure, or cell proliferation. Although Bbeta(1-42) was not necessary for matrix assembly, it was required for matrix-FBG-enhanced cell migration. These data indicate that FBG serves as an important matrix constituent in the absence of fibrin formation to enhance wound repair and implicate Bbeta(1-42) as a physiologic inducer of signal transduction to promote an intermediate state of cell adhesion and a migratory cell phenotype. (C) 2003 by The American Society of Hematology.