Temporal activity of plasminogen activators and matrix metalloproteinases during cutaneous wound repair

Background. Response to tissue injury begins with the deposition of a fibrin-rich clot or the provisional matrix. The provisional matrix consists of plasma-borne matrix molecules that serve as scaffolding for the ensuing migration of cells. During wound repair multiple cell types must migrate through the clot-matrix scaffolding: The migration of these cells through the matrix is dependent on the activity of the fibrinolytic and proteolytic systems, which include the plasminogen activator (PA) system and matrix metalloproteinases (MMP). The aim of this study was to better understand the temporal activity of these enzymes during normal wound repair. Methods. We used the murine excisional wound model and extracted proteins under nonreducing conditions, With use Of gelatin and casein zymography, we determined the activity of the MMPs during the course of wound repair In addition, we quantified the activity of MMP-2 and MMP-9 by a standardized assay. Plasminogen zymograms were used to detect urokinase PA and tissue PA activity. Western blots were used to detect the natural inhibitor of PAs, plasminogen activator inhibitor type 1. Results. Our results demonstrate the temporal activity of MMP-2, MMP-3, MMP-7, and MMP-9 during the course of normal dermal repair. The activity of urokinase PA and tissue PA were also determined; it preceded the activity of the MMPs. Conclusions. We demonstrate the temporal activity of the 2 protease families, MMPs and PAs, in the normal process of cutaneous wound healing.