Synthetic Flavonoid 3,7-Dihydroxy-Isoflav-3-Ene (DHIF) Reduces In-Stent Restenosis in an Atherosclerotic Watanabe Heritable Hyperlipidemic Rabbit Stent Model

Inflammation is a major component of the pathogenesis of atherosclerosis and the formation of in-stent restenosis (ISR). A novel flavonoid, DHIF, attenuates reactive oxygen species and nf-κB signaling and has potential to limit ISR via antioxidant action. While current drug eluting stents (DESs) perform well in clinical practice, new therapies to prevent ISR without dependance on cytotoxic drugs are warranted. Our objective was to test whether DHIF reduces ISR in a hyperlipidemic rabbit aorta model of ISR via attenuated inflammatory responses. WHHL rabbit aortas (<i>n</i> = 24) were denuded. Six weeks after injury, stents were implanted into the denuded aortas. DHIF was dissolved in carboxymethyl cellulose (CMC) and administered orally with two doses. CMC served as a control. The animals were sacrificed six weeks after stenting. ISR was evaluated from stent histomorphometry and immunohistology was used to assess the inflammatory and antiproliferative effects of the treatment. ISR was reduced from 20.9 ± 3.0% in controls to 15.2 ± 2.4% (<i>p</i> = 0.0009) and 16.4 ± 2.1% (<i>p</i> = 0.004) in the low- and high-dose groups, respectively. The neointimal area covered by macrophages was 32 ± 9.3% in the controls, 17.2 ± 5.9% (<i>p</i> = 0.005) in the low-dose group and 19.4 ± 7.9% (<i>p</i> = 0.008) in the high-dose group. DHIF significantly reduces ISR and local inflammation in stented arterial regions and could be used to reduce ISR when bare metal stents are used. Targeting local inflammation in the arterial wall may provide a way to reduce ISR in a clinical setting and further studies are warranted.