The effects of pharmacologic plasminogen activator inhibitor-1 inhibition in acute and chronic rejection in murine cardiac allografts.

BACKGROUND: Acute rejection and graft arterial disease (GAD) in cardiac transplantation limit the long-term survival of recipients; these processes are enhanced by inflammation and thrombus formation. Plasminogen activator inhibitor (PAI)-1 is critical in the inflammation and thrombus formation. However, little is known about the effect of PAI-1 in heart transplantation. Thus, the objective was to clarify the role of PAI-1 in the progression of cardiac rejection. METHODS: Murine hearts were heterotopically transplanted using major mismatch combinations for evaluation of acute rejection and class II mismatch combinations for the GAD. We administered the specific PAI-1 inhibitor (IMD-1622) into murine recipients after cardiac allografts. RESULTS: Nontreated allografts of the major mismatch group were acutely rejected, whereas the PAI-1 inhibitor prolonged their survival. Although severe cell infiltration and intimal thickening with enhancement of inflammatory factors were observed in untreated allografts of class II mismatch group on day 60, the PAI-1 inhibitor attenuated these changes. CONCLUSION: The PAI-1 inhibitor is potent for the suppression of both acute rejection and GAD.