Perivascular gene transfer of NADPH oxidase inhibitor suppresses angioplasty-induced neointimal proliferation of rat carotid artery

Vascular stretch induces NADPH oxidase-derived superoxide anion (O-2(-)), which has been implicated in hypertrophy and cell proliferation. We hypothesized that targeted delivery of an NADPH oxidase inhibitor to the adventitia would reduce stretch-induced vascular O-2(-) and attenuate neointima formation. We designed a novel replication-deficient adenovirus containing a fibroblast-active promoter driving expression of NADPH oxidase inhibitory sequence gp91ds (Ad-PDGF betaR-gp91ds/eGFP). 1) We characterized the specificity of this promoter using pPDGFbetaR-luciferase by showing induction of luciferase in cultured rat aortic fibroblasts but not in vascular smooth muscle cells. 2) Using RT-PCR, we observed expression of gp91ds and the reporter gene in fibroblasts after infection with Ad-PDGFbetaR-gp91ds/ eGFP. 3) Using Ad-CMV-eGFP as a control, we delivered Ad-PDGFbetaR-gp91ds/eGFP to the adventitia of the rat common carotid artery (CCA). Immunohistochemistry confirmed localized delivery of the inhibitor to the adventitia. After CCAs were injured with an embolectomy catheter, we observed a significant increase in neointima-to-media area ratio in control CCAs, which was significantly attenuated in CCAs treated with the gp91ds-expressing virus. In a second group of rats, we detected a 10-fold increase in distension-stimulated O-2(-), which was significantly reduced in CCAs infected with gp91ds-expressing virus. These data demonstrate that localized adventitial delivery of an NADPH oxidase inhibitor is effective in reducing overall vascular O-2(-) and neointima formation, suggesting that adventitial NADPH oxidase plays a functional role in development of neointimal hyperplasia.