Repair in arterial tissue. Demonstration of fibrinogen/fibrin in the normal and healing rabbit thoracic aorta by the indirect immunoperoxidase technique.

The results of immunoperoxidase staining for fibrinogen/fibrin in ethanol- and formaldehyde-fixed, normal and healing arterial tissue are presented. Fibrinogen/fibrin was not observed in the normal aortic wall. The thoracic aorta damaged by a balloon catheter contained fibrinogen/fibrin in all layers of the wall. In the healing aortic wall there was a strong positive reaction in neo-intima, whereas the reaction in media was weak or absent. The staining reaction for fibrinogen/fibrin in formaldehyde-fixed neo-intima covered with aortic smooth muscle cells was strong and almost independent of proteolytic digestion, while such treatment increased the staining intensity for fibrinogen/fibrin in neo-intima covered with endothelium. Our results indicate that an extracellular matrix of fibrin and fibronectin may play a role in migration and proliferation of aortic smooth muscle cells.