Matrix metalloproteinases (MMPs) are neutral zinc-dependent endopeptidases with substrate specificity for most extracellular matrix molecules. MMPs participate in physiological and pathological biological processes. In wound repair, several MMPs are upregulated in migrating epithelium although the biological significance of their presence is unknown. To elucidate the role of MMPs in epithelial migration of cutaneous wounds, a broad-spectrum synthetic MMP inhibitor (GM 6001, 10 mg/ml) was applied topically to partial-thickness wounds in domestic pigs to inhibit endogenous MMPs. The concentration of solubilized GM 6001 in wound fluid obtained from treated porcine wounds was 0.06 mg/ml (150 microM) as determined by high-performance liquid chromatography. Zymographic analysis showed that GM 6001 solubilized at this concentration abolished almost completely all enzymatic activity present in wound fluid. Epithelial coverage, assessed morphometrically, after 66 h of treatment was significantly decreased (P = 0.002) in GM 6001-treated wounds (50.0 +/- 29.6%, mean +/- SD, n = 6) compared with wounds treated with the vehicle (a hydrogel) alone (87.4 +/- 10.6%, n = 6). Topical GM 6001 did not influence the degree of dermal inflammatory cell infiltrate or the in vivo incorporation of 5-bromo-2'-deoxyuridine (as a measure of epithelial proliferation in the wounds) indicating that the reduced re-epithelialization with GM 6001 was not due to interference with the inflammatory response or epithelial proliferation. Our results suggest that MMPs are directly involved and necessary in epithelial resurfacing of moist skin wounds.