WOUND-HEALING AROUND AND WITHIN SAPHENOUS-VEIN BYPASS GRAFTS

Background: Myofibroblasts are a prominent cell type in wound healing, The goal of this study was to examine the extent to which myofibrobla sts contribute to structural changes in saphenous vein bypass grafts, Methods and results: Control veins and reversed saphenous vein bypass conduits of porcine carotid arteries were examined 2 to 4, 7 to 14, an d 30 to 90 days after surgery with immunohistochemical markers of cell ular proliferation (proliferating cell nuclear antigen), cytoskeletal protein production (alpha-smooth muscle actin and desmin), and histoch emistry (Verhoeff's stain). Control veins demonstrated an extremely lo w level of cellular proliferation and no evidence of myofibroblasts in the adventitia, media, or intima, After bypass grafting, cellular pro liferation was followed by myofibroblast formation, which occurred in the perivascular area and within the media, This was evidenced by a de nse, but transient, expression of alpha-smooth muscle actin and a vari able expression of desmin at I to 2 weeks, and with a significant incr ease in collagenous tissue by 1 to 3 months, Major cytoskeletal protei n changes also occurred in the intima, with the appearence of alpha-sm ooth muscle actin positive cells at 7 to 14 days, alpha-Smooth muscle actin was still present in the neointima at 1 to 3 months, which is co mpatible with a persistent myofibroblast formation, Conclusions: Myofi broblast formation occurs around and within saphenous veins after bypa ss grafting, This phenomenon is associated with significant remodeling of the vein grafts, The histologic changes are strikingly similar to events that occur during wound healing and may have implications for t he development of neointimal hyperplasia and late vein graft disease.