Rupture of pseudointima in an implanted vascular prosthesis: immunohistological study plasminogen activators and matrix metalloproteinases

We investigated late-onset anastomotic stenosis in an implanted prosthetic graft. Rupture of the pseudointima and hemorrhaging from the vasa vasorum w ere observed at the border of the collagenous tissue and fibrin layer. An i mmunohistological study showed that the fibrin layer was positive for tPA, but weakly positive for PAI-1. Some neutrophils and monocyte/macrophages in the fibrin layer were immunostained for tPA, uPA, uPAR, and MMP-1, -2 and -3. Some spindle-shaped cells surrounding the graft were immunostained for uPA, uPAR, MMP-1, -2, -3, -7 and -9, and TIMP-1 and -2. The endothelial cel ls of some microvessels mere positive for MMP-1 and -2, and tPA. Some multi -nucleated giant cells were immunostained for MMP-7 and-9, tPA, PAI-1, uPA, and uPAR. Overexpressed MMPs and PAs possibly caused instability of the ps eudointima.