DETAILED LOCALIZATION OF TYPE-1 PLASMINOGEN-ACTIVATOR INHIBITOR MESSENGER-RNA EXPRESSION AND ANTIGEN IN ATHEROSCLEROTIC PLAQUE ON HUMAN CORONARY-ARTERY

Objective. To accurately localize type-1 plasminogen activator inhibit or (PAI-I) both in atherosclerotic and normal human coronary arteries and to determine which cells are responsible for its production. Desig n: Immunohistochemistry and in situ hybridization over paraffin embedd ed samples obtained from patients subjected to heart transplant in 'La Fe' University Hospital, Valencia, Spain. Results: PAI-1 mRNA is clea rly detectable in atherosclerotic coronary artery, both in endothelial cells and in smooth muscle cells (SMCs) in the connective tissue of t he thickened intima, while in the core of the plaque macrophages are t he main PAI-1 producer cells. This pattern is coincident with PAI-1 an tigen localization. In arteries appearing to be normal, PAI-1 antigen and mRNA were only slightly detectable or not at all. Conclusion: PAI- 1 expression and antigen are increased in endothelial cells from ather osclerotic arteries. PAI-1 mRNA and antigen are also present in the SM Cs from thickened arteries and in macrophages in the core of the plaqu e. These results suggest that PAI-I may be involved in the development , evolution and final outcome of the atherosclerotic plaque.