AUTHOR=Hakami Nora Y. , Ranjan Amaresh K. , Hardikar Anandwardhan A. , Dusting Greg J. , Peshavariya Hitesh M. 

TITLE=Role of NADPH Oxidase-4 in Human Endothelial Progenitor Cells

JOURNAL=Frontiers in Physiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2017.00150

DOI=10.3389/fphys.2017.00150

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> Endothelial progenitor cells (EPCs) display a unique ability to promote angiogenesis and restore endothelial function in injured blood vessels. NADPH oxidase 4 (NOX4)-derived hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) serves as a signaling molecule and promotes endothelial cell proliferation and migration as well as protecting against cell death. However, the role of NOX4 in EPC function is not completely understood.</p><p><bold>Methods:</bold> EPCs were isolated from human saphenous vein and mammary artery discarded during bypass surgery. NOX4 gene and protein expression in EPCs were measured by real time-PCR and Western blot analysis respectively. NOX4 gene expression was inhibited using an adenoviral vector expressing human NOX4 shRNA (Ad-NOX4i). H<sub>2</sub>O<sub>2</sub> production was measured by Amplex red assay. EPC migration was evaluated using a transwell migration assay. EPC proliferation and viability were measured using trypan blue counts.</p><p><bold>Results:</bold> Inhibition of NOX4 using Ad-NOX4i reduced Nox4 gene and protein expression as well as H<sub>2</sub>O<sub>2</sub> formation in EPCs. Inhibition of NOX4-derived H<sub>2</sub>O<sub>2</sub> decreased both proliferation and migration of EPCs. Interestingly, pro-inflammatory cytokine tumor necrosis factor alpha (TNFα) decreased NOX4 expression and reduced survival of EPCs. However, the survival of EPCs was further diminished by TNF-α in NOX4-knockdown cells, suggesting that NOX4 has a protective role in EPCs.</p><p><bold>Conclusion:</bold> These findings suggest that NOX4-type NADPH oxidase is important for proliferation and migration functions of EPCs and protects against pro-inflammatory cytokine induced EPC death. These properties of NOX4 may facilitate the efficient function of EPCs which is vital for successful neovascularization.</p>