Potentially positive ageing-related variations of medial smooth muscle cells in the saphenous veins used as aortocoronary bypass grafts.

Abstract

Currently, elderly people constitute a large proportion of patients undergoing coronary artery bypass grafting (CABG). Activated smooth muscle cells in the tunica media of saphenous vein (SV) grafts are thought to play a key role in the formation of neointima and development of occluding atherosclerotic plaques. The aim of this study was to identify ageing-related variations in the expression of the smooth muscle cells pro-teins that may impact on patency rate of the grafts and the CABG outcomes. The study involved 216 consecutive patients with the mean of 62.7 ± 8.4 years who underwent isolated CABG with at least one SV aortocoronary bypass graft. Expression of a-smooth muscle actin (a-SM actin), smooth muscle-myosin heavy chain (SM-MHC), calponin (CALP), cytokeratin 8 (CK-8), metalloproteinase-2 (MMP-2) and tissue inhibitors of metalloproteinases-2 and -3 (TIMP-2, TIMP-3) in the SV wall was assessed by immunohistochemistry and correlated with the age of patients. Calponin and a-SM actin were expressed in all studied SV transplants. SM-MHC immunoreactivity was observed in SV segments in 68.5% of patients, whereas MMP-2a and TIMPs expression was found in 75% of cases. In more than 50% of analyzed SV transplants, no expression of cytokeratin-8 was found. Moderate correlations between preexisting expressions of either cytoskeletal or hemostatic proteins in the tunica media of the SV grafts and the age of CABG patients were demonstrated. They were positive for SM-MHC (r = 0.494), CALP (r = 0.548), TIMP-2 (r = 0.413) and TIMP-3 (r = 0.406) whereas negative for CK-8 (r = -0.528) and MMP-2 (r = -0.417). Age-dependent decreases in the expression of MMP-2 and CK-8 accompanied by increases in expression of SM-MHC, TIMP-2 and TIMP-3 may promote SV graft patency and, thus, suggest a rationale for common use of SV grafts in the elderly.