Pre-existing intimal hyperplasia and overexpression of TGF-ß1 in saphenous vein grafts before myocardial revascularization in humans: implications for aortocoronary saphenous vein graft disease
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Saphenous vein graft disease still remains an important and unresolved dilemma in clinical bypass surgery. TGF-beta-1 is known to act as a proatherogenic, profibrotic growth factor. We have therefore investigated the incidence of intimal hyperplasia in saphenous veins and internal thoracic arteries before coronary artery bypass grafting using morphometric analysis. Then we applied immunohistochemistry to assess the expression of TGF-beta-1, LTBP1, RII, and fibronectin. We found that SV grafts have a thicker intima and media both in area and width than ITA grafts. The intimal hyperplasia is more prevalent and serious in SV grafts compared to ITA grafts. We found a significantly higher expression of TGF-beta-1, LTBP-1 and RII mainly in intimal and medial layers in SV and ITA grafts with intimal hyperplasia as compared to SV and ITA grafts without intimal hyperplasia. TGF-beta-1 may therefore be of importance in mediating the development of intimal hyperplasia in vivo. In summary, in this study we demonstrated that the development of intimal hyperplasia occurs in a high degree in SV grafts before arterialisation, and in a lower percentage also in internal thoracic arteries. Growth factor expression was increased in areas of intimal hyperplasia. Thus, locally active TGF-beta-1 might be involved in mediating intimal thickening in SV before arterialisation and might even aggravate this phenomenon after arterialisation contributing to a rapidly progressive vein graft disease.
Subject HeadingsTransforming Growth Factor beta 1 [GND]
Transforming growth factor beta [LCSH]
Coronary artery bypass [MeSH]
Heart surgery [MeSH]
Myocardial revascularization [MeSH]