Abstract 1174: Nitric Oxide Mediates Migration of Endothelial Cells and Circulating Progenitor Cells Through Both Nitric Oxide Synthase (NOS)-Dependent and NOS-Independent Processes
S-Nitrosothiols represent a bioactive NO storage pool and are decreased in plasma of humans with cardiovascular risk factors. Impaired vascular maintenance was associated with dysfunction of endothelial cells and endothelial progenitor cells (EPCs). We thus hypothesized that the migration of endothelial cells and EPCs is NOS-dependent and is enhanced by S-nitrosothiols. Using timelapse microscopy of cultured human uterine microvascular endothelial cells and human umbilical vein endothelial cells (HUVECs), we observed that the formation of capillary tubes by each was abolished by inhibition of NOS using L-NNA, while random movement was not abolished. EPCs were isolated from peripheral blood of human volunteers (n = 4), and migratory capacity of both EPCs and HUVECs was measured in culture. This was accomplished by plating 2– 4x104 cells in one of two chambers divided by a membrane with 8 μm pores, and adding VEGF to the other chamber as a chemoattractant. After 6 h, we counted the migrated cells on the opposite side of the membrane. HUVECs and EPCs (Fig⇓.) exhibited similar chemotaxis toward VEGF that was abolished by L-NNA. Addition of the S-nitrosothiol NO-donor SNAP (S-nitroso-N-acetyl-penicillamine) to both chambers enhanced random cell movement (white bars), while chemotaxis toward VEGF in the presence of SNAP increased cell migration synergistically (striped bars). In the latter case, L-NNA inhibited the chemotaxis to VEGF but did not affect the enhanced random movement of cells exerted by SNAP. We conclude that random cell movement of endothelial cells and EPCs is modulated by S-nitrosothiols but NOS-independent, while chemotaxis and tube formation are NOS-dependent.