Shear stress promotes nitric oxide production in endothelial cells by sub-cellular delocalization of eNOS: A basis for shear stress mediated angiogenesis.

This study aims to investigate the role of shear stress in cellular remodeling and angiogenesis with relation to nitric oxide (NO). We observed a 2-fold increase in endothelial cell (EC) migration in relation to actin re-arrangements under 15 dyne/cm(2) shear stress. Blocking NO production inhibited the migration and ring formation of ECs by 6-fold and 5-fold, respectively under shear stress. eNOS-siRNA knockdown technique also ascertained a 3-fold reduction in shear stress mediated ring formation. In ovo artery ligation model with a half and complete flow block for 30 min showed a reduction of angiogenesis by 50% and 70%, respectively. External stimulation with NO donor showed a 2-fold recovery in angiogenesis under both half and complete flow block conditions. NO intensity clustering studies by using Diaminofluorescein diacetate (DAF-2DA) probed endothelial monolayer depicted pattern-changes in NO distribution and cluster formation of ECs under shear stress. Immunofluorescence and live cell studies revealed an altered sub-cellular localization pattern of eNOS and phospho-eNOS under shear stress. In conclusion, shear-induced angiogenesis is mediated by nitric oxide dependent EC migration.