Fourier transform infrared spectroscopy application to vascular biology: comparative analysis of human internal mammary artery and saphenous vein wall

Saphenous vein (SV) and internal mammary artery (IMA) are used for aorto-coronary bypass grafting. IMA is considered to be the graft of choice for coronary revascularization having a long-term patency compared to SV. The aim of this study is to investigate the structure of vascular wall using a new technical approach. We analysed the chemical composition of vessel wall layers (total lipid, lipid ester and protein) of 25 vascular segments (19 SV and 6 IMA) using Fourier transform infrared spectroscopy (FTIR). FTIR analysis showed that in intima layer lipid ester and protein concentration (expressed as arbitrary units) was significantly higher in SV (lipid ester = 0.020 ± 0.002; protein = 0.449 ± 0.022) than in IMA (lipid ester = 0.014 ± 0.002; protein = 0.342 ± 0.032). Moreover, the percentage of lipid ester on total lipid was significantly higher in SV (intima = 54.7 ± 2.9%; media = 78.4 ± 4.9%; adventitia = 83.9 ± 8.3%) wall layers compared to IMA ones (intima = 37.3 ± 4.9%; media = 45.4 ± 3.8; adventitia = 57.1 ± 4.8). These data suggest that a different chemical composition of wall layers could also be responsible for the morphological modifications observed in SV after grafting.