Long-term preservation of human saphenous vein by green tea polyphenol under physiological conditions

Polyphenolic compounds are well known as a functional food with various bioactivities. However, less attention has been paid to the effect of phenolic antioxidants on the preservation of blood vessels. In this study, the possible effects of green tea polyphenolic compounds ( GTPCs) on the longterm preservation of the human saphenous vein ( HSV) were investigated under physiological conditions. HSV segments were pretreated with GTPCs ( 0.5 or 1.0 mg/ mL) for 1 day and then incubated for 1, 2, 4, or 8 weeks. After incubation, cellular viability, endothelial nitric oxide synthase ( eNOS) expression level, biomechanical properties, and vein histology were evaluated. When HSV segments were incubated without GTPC treatment, endothelial cell viability was significantly ( p < 0.05) reduced with incubation time, and none of the endothelial cells expressed eNOS after 2 weeks. Furthermore, nontreated veins demonstrated appreciable inferiority in such mechanical properties as failure strength, elastic modulus, and compliance, compared with fresh veins. These results were confirmed by histological observations, which showed severe structural changes in nontreated veins. On the other hand, these phenomena were markedly prevented by preincubating veins with GTPCs ( 1.0 mg/ mL) at 37 degrees C in a CO2 incubator for 1 day. GTPC- pretreated veins could be preserved for at least 2 weeks under physiological conditions, retaining cellular viability and eNOS expression level and maintaining both biomechanical properties and vascular structures without any morphological alterations. These results demonstrate that GTPC treatment may be a useful method for preserving the HSV and could be exploited to craft strategies for the long- term preservation of other tissues under physiological conditions.