803-2 Histological and Molecular Biological Characteristics of Restenotic Sapheneous Vein Grafts Post-Angioplasty

Vascular repair of vein grafts following angioplasty appears to be different from arterial vascular repair. This prompted us to investigate atherectomy specimens of patients who had undergone CABG surgery and underwent one or more angioplasties in a vein graft at the same site. for histology and TGF-β1 gene expression. 11 atherectomy specimens, 7 of patients with single and 4 of patients with multiple restenosis events were investigated. The mean time interval from the last restenosis event was 7.3±5.2 months. Immunohistochemistry was performed using antibodies against α-actin, desmin, collagen I and IV, macrophages, monocyte-derived macrophages, endothelial structures and proliferation markers. In situ hybridization using a specific cDNA probe for TGF-βl was performed and silver grains over nuclei and arbitrarily defined areas, indicating TGF-β1 expression, were counted. In adjacent sections cell density and areas containing extracellular neo-matrix were measured. Restenosis tissues compared with primary lesions showed a higher incidence of cellular components (70% vs 10%) and a lower macrophage content (20% vs 43%). Myocytes of varying phenotypes were seen in restenosis tissues, mainly meeting the criteria for “myofibroblasts”. The area of extracellular neo-rnatrix correlated with the time interval of restenosis (r=0.63). and both TGF-β1 expression and extracellular neo-matrix formation inversely correlated with cell density (r=0,81 and r=0.69, respectively). TGF-β1 expression was greater in lesions that had multiple restenotic events (15.1±6.1 vs 5.6±5.1 grains/nucleus, p<0.05).ConclusionHistological features of restenotic sapheneous vein grafts post-angioplasty are high cellularity, high “rnyofibroblast” and low macrophage content. TGF-β1 gene expression is almost 3-fold increased in patients with multiple vs single restenosis events in sapheneous vein grafts. Overall, extracellular neo-matrix formation was continuously increased over time