Objective To investigate collagen Ⅳ and matrix metalloproteinase-2 (MMP-2)expression in intimal hyperplasia(IH) in rat vein grafts. Methods Vein graft model was constructed in rats. At day 3,week 1,2,4,8 and 12 after surgery,vein grafts were obtained and examined by HE and Verhoeff stains. The thickness and area ratio of intima/media were measured. The positive cells of 5′-Brdu were detected to indicate SMC proliferation. The positive ratio of collagen Ⅳ and MMP-2′s protein and mRNA were calculated. Results The neointima was found at 1 week post-operation. The maximal IH occurred at 2 to 4 week. The similar tendency was observed in the positive cells of 5′-Brdu. Collagen Ⅳ was on the decrease at 1 week and negative from 2 to 8 week ( P

Objective:The aim of this study was to identify fibrinogen ( FG ) on the development of intimal hyperplasia ( IH ), using an organ culture model. Methods：Segments(n=9 ) of human saphenous vein ( HSV ) wereharvested during coronary artery or infrainguinal vein bypass surgery. The culture medium supplemented with FG (from0 mg/ml to 5 mg/ml ). The proliferation of smooth muscle cell ( SMC ) quantified by 5′-Bromodeoxyuridine (5′-BrdU) uptake in the final four days of the culture period. Histologic analysis and computerized morphometric analysis were used to determine intimal and medial thickness and area，then the intima/media thickness ratio and intima/media area ratio were calculated. Monoclonal antibodies to 5′-BrdU were used as an immunohistochemical maker for proliferating SMC. Results：Addition of FG ( 2.5 mg/ml ) to the cultured medium caused a significant increase in median ( range ) of intima/media thickness ratio and intima/media area ratio of these segments when compared with the normal cultured vein segments ( Wilcoxon paired rank test )：0.387versus 0.215（P=0.017 ）and 0.396 versus 0.229（P=0.015 ），respectively. Addition of FG ( 5.0 mg/ml ) to the cultured medium also caused a significant increase in median ( range ) of intima/media thickness ratio and intima/media area ratio of these segments when compared with the normal cultured vein segments: 0.421 versus 0.215（P=0.008 ）and 0.382 versus 0.229 （P=0.011 ），respectively. However，there were no significant differences in the two vein segments which 2.5 mg/ml or 5.0 mg/ml FG in cultured medium (P>0.05 ).In addition, there was no significant difference in the median ( range ) of intima/media thickness ratio and intima/media area ratio of the segments which FG ( 0.5 mg/ml ) in cultured medium when compared with the normal cultured vein segments ( P>0.05 ). These were supported by SMC proliferation index using staining with 5′-BrdU. Conclusion：High concentration FG at local preianastimotic area may an important factor for IH and early postoprative vein graft restenosis or occlusion.

Objective: To investigate the effect of inhibitng C-myc expression by actinomycin D on intimal hy-perplasia in vein graft. Methods: The vein graft model was established in rats. The different dises of actinomycin D (0.015 mg/kg; 0.15 mg/kg) were given just before and after operation. The vein grafts were harvested at 2 hrs and 1 week after grafting. C-myc mRNA was measured by in situ hybridization method. The intimal thickness was measured using a computerised image analysis system. Results: The expression of C-myc mRNA and the intimal thickness were both significantly reduced in large dose (0.15 mg/kg) group of actinomycin D, with 6.5%; 18.7 μm compared with control group in 12.5%; 28.5 μm respectively. Conclusion: Actinomycin D can inhibit expression of C-myc mRNA and intimal hyperplasia in graft. Expression of C-myc plays an important role in inducing proliferation of smooth muscle cell in vein graft.