Endogenously produced nitric oxide inhibits endothelial cell growth as demonstrated using novel antisense cell lines

1 Proliferation of endothelial cells is a vital component of vascular repai r and angiogenesis. The endothelial cell mediator, nitric oxide (NO) has be en reported both to inhibit and to promote endothelial cell proliferation. In this study we have generated cell lines which constitutively express ant isense RNA to a region of inducible nitric oxide synthase (iNOS) from a mur ine endothelial cell line, sEnd-1. 2 In response to stimulation with lipopolysaccharide (LPS) and interferon-g amma; (IFN-gamma;) these antisense cells had no detectable RNA for endogeno us iNOS, barely detectable iNOS protein and produced 82% less NO than did t he control transfected line. 3 Stimulation of the control transfected line caused significant NO product ion and inhibition of cell growth whereas for the antisense line, producing little NO in response to stimulation, proliferation remained the same as f or unstimulated cells. No differences in cell death were observed between u nstimulated and LPS/IFN-gamma stimulated cells. 4 The data presented in this study directly demonstrate that NO derived end ogenously from iNOS inhibits proliferation of endothelial cells. This appro ach overcomes problems in other studies where NO donors or non-isoform spec ific inhibitors of NO synthase have been used.