Alterations in c-fos expression, cell proliferation and apoptosis in pressure distended human saphenous vein

Objectives: Saphenous vein graft failures, resulting from thrombosis and the abnormal proliferation, migration and apoptosis of vascular smooth muscle cells (VSMC) are major limitations of coronary artery bypass surgery. We investigated whether surgical trauma of human saphenous vein induces the early response gene c-Sos and causes alterations in rates of proliferation and apoptosis. Methods: Surgically prepared human vein consisted of distended (at 350 mmHg for 2 min) or non-distended segments of vein maintained in serum free RPMI at 37 degrees C and 5% CO2 for various time intervals. c-fos expression was detected by Northern analysis. Cell proliferation and apoptosis were determined by [H-3]thymidine incorporation combined with proliferating cell nuclear antigen (PCNA) immunostaining and TUNEL, respectively. Labelling indices for proliferation and apoptosis were correlated with vessel wall thicknesses. Results: Control, freshly isolated vein expressed no c-Sos. Surgically prepared vein synthesized c-Sos 1 h following harvesting. There was a significant increase in c-fos in distended compared to non-distended vein. c-Fos protein increased in surgically prepared vein 24 h after harvesting. There was a significant increase in vascular cell proliferation in the non-distended compared to the distended vein: mean (S.E.M.) 1279 (218) vs. 863 (155) dpm/mu g DNA, P<0.05, n=6. In addition, the apoptotic index was significantly lower in the media of non-distended vs. distended vein 0.82 (0.2) vs. 5.5 (1.5), P<0.05. n=5, Conclusions: These findings demonstrate that surgical preparation of human saphenous vein increases expression of c-Sos mRNA and apoptosis and reduces proliferation when compared with non-distended vein. These changes may influence the failure of saphenous vein grafts. (C) 1999 Elsevier Science B.V. All rights reserved.