Protection and preservation of vascular cells and tissues by green tea polyphenols

Green tea polyphenols (GTPs) are well known as functional foods with variousbioactivities. Conventional studies have typically focused on antioxidant, anticancer,anti-inflammatory and antimicrobial effects of GTPs. Para-hydroxyl, catechol and galloylgroups of catechins are mainly responsible for these biological activities. A newpromising field in polyphenols research is the study on the use of GTPs for non-frozenpreservation of mammalian cells and tissues. This chapter therefore concentrates on thebeneficial cardiovascular effects of GTPs, especially on those aspects related to theprotection and preservation of vascular cells and tissues. In the first part, we give anoverview of the antioxidant activity of GTPs in protection of endothelial cells (ECs) andblood vessels from reactive oxygen species-induced injury. We then discuss the antiproliferativeactivity of GTPs to prevent abnormal growth and migration of vascularsmooth muscle cells (VSMCs) that are involved in vascular diseases, includingatherosclerosis and re-stenosis after angioplasty. We finally argue in favor of thepotential usability of GTPs in the preservation of vascular tissues under physiologicalconditions. Pre-treatment with GTPs can indeed protect human ECs and saphenous vein against oxidative stress. Treatment with epigallocatechin-3-O-gallate (EGCG), a majorpolyphenolic constituent of green tea, also results in significant inhibition of attachment,proliferation and migration as well as cell-cycle arrest in serum-stimulated VSMCs.Moreover, these behaviors of VSMCs are effectively suppressed onto EGCG-releasingbiodegradable polymers that might be applied for the development of an EGCG-elutingvascular stent. Furthermore, GTP-pretreated veins can be preserved in a non-frozen statefor at least 2 wk, maintaining their vascular cell viability and vasculature without anystructural alterations. Therefore, GTPs may be usefully exploited to establish strategiesfor the protection and preservation of ECs and vascular tissues.