A novel model of intimal hyperplasia with graded hypoosmotic damage

MEK1/2 inhibitor inhibits neointima formation by activating miR-126-3p/ C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) axis

Endothelial dysfunction is an initial and essential step in vascular-remodeling diseases, including atherosclerosis and neointima formation. During vascular remodeling, activated endothelial cells can release pro-inflammatory factors that promote phenotypic switching of vascular smooth muscle cells (VSMCs) to the proliferative phenotype. We previously reported that MEK1/2 inhibitor, U0126, has a protective effect on the development of atherosclerosis and vascular calcification. However, the effect of MEK1/2 inhibitors on neointimal formation and the underlying mechanism is not fully understood. We determined that MEK1/2 inhibitor reduced carotid artery ligation-induced neointimal formation, while increased collagen and elastin levels and vascular integrality. Mechanistically, MEK1/2 inhibitor or ERK1/2 siRNA increased miR-126-3p level in endothelial cells, thereby inhibiting expression of regular of G-protein signaling 16 (RGS16), a miR-126-3p target gene, to activate the C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) signaling pathway. Accordingly, miR-126-3p was also increased by U0126 in serum and carotid artery. RGS16 was inhibited while CXCR4 and CXCL12 was increased by U0126 in neointimal areas, especially in the endothelium. Moreover, similar results were observed in atherosclerotic plaques of high-fat diet-fed apolipoprotein E deficiency (apoE^−/−) mice. In addition, vascular cell adhesion molecule 1 (VCAM-1), another miR-126-3p target gene, was reduced by U0126 in the neointimal areas, resulting reduced monocytes/macrophages accumulation. Taken together, our results indicate that MEK1/2 inhibitor can reduce neointima formation by activating endothelial miR-126-3p production to facilitate endothelium repair while reduce monocyte adhesion/infiltration.

Inhibition of Aortic Intimal Hyperplasia and Vascular Smooth Muscle Proliferation and Extracellular Matrix Protein Expressions by Astragalus-Angelica Combination

VSMC proliferation and ECM deposition always resulted in intimal hyperplasia. Astragalus–Angelica combination has a protective effect on the cardiovascular system. The inhibition effect of different Astragalus–Angelica combination on the hyperplastic intima after vascular balloon injury in rats was investigated in this study. Astragalus–Angelica combination can inhibit the intima hyperplasia after balloon injury, in which a 1:1 ratio shows excellent results. Astragalus–Angelica combination can enhance the expression of smooth muscle α-actin (SMа-actin) and inhibit the expression of proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin E, collagen I (Col-I), fibronectin (FN), and matrix metallopeptidase-9 (MMP-9) in hyperplastic intima, suggesting that Astragalus–Angelica combination can inhibit the intimal hyperplasia of blood vessels in rats. The mechanism is related to the inhibition of PI3K/Akt signaling pathway activation and thereby inhibits the phenotypic transformation and cell proliferation of VSMCs and thus inhibits the extracellular matrix (ECM) deposition of vascular wall during intimal hyperplasia.

An animal model of atherosclerotic plaque disruption and thrombosis in rabbit using pharmacological triggering to plaques induced by perivascular collar placement

INTRODUCTION

Limited availability of suitable animal model of plaque disruption and thrombosis has hampered the study of mechanism and preclinical evaluation of plaque-stabilizing therapies. This study aims to develop an animal model of atherosclerotic plaque disruption and thrombosis in rabbit femoral artery.

METHODS

Silastic collars were placed around the bilateral femoral arteries of rabbits, which had been fed with atherogenic diet for 7 days. After 28 days on the same diet, the rabbits received pharmacological triggering by intraperitoneal injection of Russell's viper venom (RVV, 0.15 mg/kg) followed by intravenous injection of histamine (0.02 mg/kg), and the animals were then processed for imageological and histological examinations.

RESULTS

Perivascular collar placement of the femoral artery in high-cholesterol-fed rabbits for 28 days induced marked intimal hyperplasia, which was a lipid- and collagen-rich lesion that contained substantial amount of macrophages and smooth muscle cells. Subsequent histological analysis showed that the pharmacological triggering evoked plaque disruption and platelet- and fibrin-rich thrombi in the collared femoral arteries.

CONCLUSION

We demonstrated, for the first time, a rabbit model of plaque disruption and thrombosis induced by the combination of perivascular collar placement, RVV, and histamine injections. This model can be rapidly formed, easily operated, and site controlled.