Differential effects of acute and chronic wound fluids on urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor, and tissue-type plasminogen activator in cultured human keratinocytes and fibroblasts.

Abstract

The effect of wound fluids collected from acute well-healing wounds and chronic nonhealing venous leg ulcers on the plasminogen activation system of keratinocyte and fibroblast cell cultures was studied in a simplified wound-healing model. Acute wound fluid was collected from donor sites of split skin grafts at different time points representing the progressive healing of the wound. Urokinase-type plasminogen activator, tissue-type plasminogen activator, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor 1 expression were studied. The methods used were immunocapture assay and immunocytochemistry. The results indicated that the later the acute wound fluid was collected, the greater the urokinase-type plasminogen activator and the lower the plasminogen inhibitor-1 level in treated cells. In contrast, the level of urokinase-type plasminogen activator receptor remained stable irrespective of wound fluid treatment. Immunostaining for urokinase-type plasminogen activator of acute wound fluid-treated cells showed a disseminated punctate pattern over the cell surface, but with chronic wound fluid, urokinase-type plasminogen activator was localized to focal contacts. Our findings support the view that in the acute wound environment the plasminogen activator system is proteolytically active and that in chronic leg ulcers urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor may also be organized for cell adhesion and migration.