Abstract 517: The CYP4A-20-HETE System Regulation of Endothelial Progenitor Cell Functions that Associated with Angiogenesis

Abstract

The CYP4A-20-HETE system regulates the neovascularization process via its potent vascular effects mainly on endothelial cells and vascular smooth muscle cells. Endothelial progenitor cells (EPC) also actively participate in physiological and pathological neovascularization. Our group first reported that the CYP4A-20-HETE system is present and functional in EPC derived from human umbilical cord blood (HUCB) and that EPC also respond to exogenous 20-HETE with increased proliferation and migration. We hypothesized that the angiogenic actions of the CYP4A-20-HETE system may involve regulation of EPC functions that associated with angiogenesis. In this study, we identified CYP4A11/22 as the main 20-HETE synthases in EPC derived from HUCB by real time PCR. We also examined the effects of exogenous 20-HETE on EPC adhesion since adhesion of EPC to extracellular matrix is an important aspect of EPC homing to the sites where angiogenesis is occurring. We found that 20-HETE (1 μM) increased EPC adhesion to fibronectin and SDF-1α coating by ∼40% and ∼35%, respectively. These increases in adhesion are completely abolished in the presence of 20-hydroxy-6, 15-eicosadienoic acid (20-HEDE), a 20-HETE antagonist. We further established the mouse ischemic hindlimb model to study the effects of pharmacological inhibition of the CYP4A/F-20-HETE system using the 20-HETE synthase inhibitor Dibromo-dodecenyl-methylsulfimide (DDMS) and 20-HEDE on compensatory angiogenesis in response to ischemia. Systemic treatment of animals with 10 mg/kg/day of either DDMS or 20-HEDE inhibited hindlimb compensatory angiogenesis by more than 50% without significant effects on the blood pressure. Specific targeting of the EPC-derived CYP4A-20-HETE system needs to be performed to further dissecting the role of systemic and EPC-derived 20-HETE on angiogenic processes. These findings implicates the CYP4A-20-HETE system as a novel regulator of EPC functions that are associated with angiogenesis and suggests that it can act as both an autocrine and paracrine regulatory factor.