Nitric oxide treatment reduces neo-intimal formation and modulates osteopontin expression in an ex-vivo human model of intimal hyperplasia

Abstract

In this study the effects of nitric oxide (NO) on intimal hyperplasia (IH) were evaluated in an ex-vivo model of human saphenous vein (SV). SV segments were cultured in conditions able to reproduce IH (FCS), or in medium alone (RPMI), or in presence of a NO donor (NO). Osteopontin (OPN) and Interleukin (IL)-6 were determined in the medium at different culture times and in the tissue, at the end of experiment. OPN and IL-6 release in medium was increased in FCS with respect to RPMI (OPN: 13.9 ± 2.9 vs. 2.3 ± 0.8 μg/ml, p = 0.0011; IL-6: 304.2 ± 64.7 vs. 42.0 ± 10.1 ng/ml, p < 0.0006) as well as intima thickness, that positively correlated with OPN production ( r = 0.81). In tissue OPN was higher in FCS (82.0 ± 30.3 ng/mg protein) than in RPMI (13.8 ± 4.2, p = 0.0051) and at baseline (3.7 ± 0.7, p = 0.018). NO reduces IH progression (25%) and both OPN and IL-6 expression (OPN/GAPDH: undetectable baseline; 0.27 ± 0.06 RPMI; 0.89 ± 0.28 FCS; 0.09 ± 0.05 NO; p = 0.026 FCS vs. baseline, p = 0.018 vs. RPMI, p = 0.005 vs. NO). The beneficial NO effect on IH reduction appears to be mediated by the indirect inhibition of OPN production. NO could modulates the initial inflammatory signals that induces the OPN over-production with the related cascade of events leading to IH.