Abstract 104: Angiotensin Converting Enzyme 2 Regulates Endothelial Progenitor Cell Function Through the eNOS and NAPDH Oxidase Pathways

Abstract

Angiotensin converting enzyme 2 (ACE2) is a key vasoprotective member of the renin-angiotensin system that catalyzes angiotensin II (Ang II) into Ang (1-7). We have shown endothelial progenitor cells (EPCs) from the hypertensive human renin and angiotensinogen transgenic (R+A+) mice are dysfunctional. Here, we studied the role of ACE2 in EPC function. Bone marrow derived-EPCs were cultured from R+A+ mice and its controls(R-A-). EPCs (1×10 5 cells/well) were transduced with 5×10 6 infectious units of lentivirus-ACE2 (Lenti-ACE2) or Lenti-GFP. The levels of ACE2, endothelial nitric oxide synthase (eNOS) and NADPH oxidase subunits (Nox2, 4) were measured by Western blot. EPC functions (migration and tube formation) were evaluated using the Boyden chamber method and an assay kit. For blocking experiments, ACE2 inhibitor (DX600) or eNOS inhibitor (L-NAME) was added in culture medium. Reactive oxygen species (ROS) and nitric oxide (NO) production in EPCs was determined by dihydroethidium staining and 4, 5-diaminofluorescein method. We observed that 1) eNOS expression and NO production were lower, whereas Nox2, 4 expression and ROS production were higher in the EPCs from R+A+ mice. 2) Lenti-ACE2 transduction resulted in an 8-fold increase in ACE2 expression in EPCs. This was associated with an increases in eNOS expression and NO production, while decreases in Nox2, 4 expression and ROS production. 3) ACE2 over-expression enhanced migration and tube formation function of EPCs from R+A+ mice. 4) The effects of ACE2 over-expression on EPCs were able to be partially inhibited by DX600 or L-NAME. In conclusion, our data demonstrate that ACE2 improves EPC function via eNOS and Nox pathways.