PLASMINOGEN ACTIVATION IN HEALING HUMAN WOUNDS

Tissue injury is followed by formation of a provisional, fibrin-contai ning matrix. It is later on replaced by granulation tissue. Replacemen t involves extracellular proteolysis by fibrinolytic enzymes. Plasmin is a fibrinolytic proteinase and is generated from ubiquitous plasmino gen by cell-derived urokinase-type (uPA) or tissue-type (tPA) plasmino gen activator To explore the cells and components involved in plasmino gen activation, we have performed a combined immunohistological and zy mographic study on human skin wounds produced iatrogenically by debrid ement. The fibrin(ogen)-specific staining indicated the progressive re moval of a fibrin-containing provisional matrix Plasmin(ogen) was pres ent over the entire observation period It was diffusely distributed an d also displayed a conspicuous association with cells of the granulati on tissue, in particular with monocytes/macrophases and fibroblasts. A lso, uPA was associated with monocytes/macrophages and fibroblasts, wh ereas the uPA-receptor (uPA-R) was stained in monocytes/macrophages on ly. The uPA was potentially active as indicated by zymography. No tPA- specific staining was found The findings point at the importance of mo nocytes/macrophages and fibroblasts in uPA-mediated plasminogen activa tion in healing human skin wounds.