Simvastatin decreases stent-induced in-stent restenosis rate via downregulating the expression of PCNA and upregulating that of p27kip1.

ABSTRACT

BACKGROUND: The inhibition of the proliferation and migration of vascular smooth muscle cells (VSMC) is one cholesterol-independent effect of statins that could lower the rate of in-stent restenosis (ISR), even if the exact mechanism remains unclear. The aim of this study was to explore the exact inhibitory mechanisms of simvastatin on ISR in vivo. METHODS: Forty-five rabbits were randomized into 3 feeding groups of equal size (n=15) normal rabbit chow (normal group), a high-cholesterol diet (control group), and a simvastatin-enriched high-cholesterol diet (simvastatin group). Balloon de-endothelialization was first performed in the control and simvastatin groups after 3 days, followed by stent deployment at week 14. All rabbits were killed at week 18, and the histological changes of the ISR segments were observed. The expressions of cyclin-dependent kinase inhibitor p27 (p27kip1), proliferating cell nuclear antigen (PCNA), and α-smooth muscle (α-SM) actin were measured. RESULTS: In the simvastatin group compared to the control group, the neointimal thickness, neointimal area, and degree of stenosis decreased, while the residual lumen area increased significantly (P<0.05). Moreover, the expression of α-SM actin in the control group decreased by 55.4% compared to the normal group, while it increased by 29.7% with respect to the simvastatin group (P<0.05). Finally, the expression of p27kip1 increased, while that of PCNA decreased significantly in the simvastatin group compared to the control group (P<0.05). CONCLUSIONS: Simvastatin may inhibit VSMC phenotype modulation and proliferation by downregulating the expression of PCNA and upregulating that of p27kip1.