MIGRATION OF ARTERIAL-WALL CELLS - EXPRESSION OF PLASMINOGEN ACTIVATORS AND INHIBITORS IN INJURED RAT ARTERIES

The expression of plasminogen activators and inhibitors was examined i n denuded arteries. Within 5 days, smooth muscle cells (SMCs) on the l uminal surface expressed the mRNA for tissue-type plasminogen activato r (TPA), urokinase-type plasminogen activator (UPA), the receptor for UPA (UPAR), and plasminogen activator inhibitor type-1 (PAT-1). Simila r results were seen after 8 days. Six weeks later, only TPA mRNA was s till expressed by SMCs on the luminal surface. En face casein zymogram s revealed a net fibrinolytic activity in areas covered with luminal S MCs. Reverse zymography showed no antifibrinolytic activity in these z ones. Quiescent endothelial cells did not express TPA, UPA, UPAR, or P AI-1 mRNA. Regenerating endothelium at the wound edge strongly express ed TPA, UPA, and UPAR, as well as PAI-1. UPA and UPAR expression was h ighly restricted to cells at the wound edge and was not present elsewh ere. En face zymography showed no plasmin activity in endothelialized areas, and reverse zymography showed a net antifibrinolytic activity i n endothelialized zones. These results suggest that plasminogen activa tor and inhibitor expression correlates with the migration of both SMC s and endothelial cells into an arterial wound.