Rosuvastatin reduces neointima formation in a rat model of balloon injury

Abstract

Background: Processes of restenosis, following arterial injury, are complex involving different cell types producing various cytokines and enzymes. Among those enzymes, smooth muscle cell-derived matrix metalloproteinases (MMPs) are thought to take part in cell migration, degrading of extracellular matrix, and neointima formation. MMP-9, also known as gelatinase B, is expressed immediately after vascular injury and its expression and activity can be inhibited by statins. Using an established in vivo model of vascular injury, we investigated the effect of the HMG-CoA reductase inhibitor rosuvastatin on MMP-9 expression and neointima formation.

Materials and methods: 14-week old male Sprague Dawley rats underwent balloon injury of the common carotid artery. Half of the animals received rosuvastatin (20 mg/kg body weight/day) via oral gavage, beginning 3 days prior to injury. Gelatinase activity and neointima formation were analyzed 3 days and 14 days after balloon injury, respectively. 14 days after vascular injury, proliferative activity was assessed by staining for Ki67.

Results: After 14 days, animals in the rosuvastatin group showed a decrease in total neointima formation (0.194±0.01 mm2 versus 0.124±0.02 mm2, p<0.05) as well as a reduced intima/media ratio (1.26±0.1 versus 0.75±0.09, p<0.05). Balloon injury resulted in increased activity of MMP-9 3 days after intervention for both rosuvastatin treated animals and controls with no significant difference observed between the groups. There was a trend towards a reduction in the number of Ki67-positive cells 14 days after injury.

Conclusions: Rosuvastatin attenuates neointima formation without affecting early MMP-9 activity in a rat model of vascular injury.

Figure 1

Neonintima formation of the common carotid artery (hematoxylin/eosin staining) 14 days after balloon injury in a control animal (A) and an animal treated with rosuvastatin. (B) Treatment with rosuvastatin leads to a reduction of neointima size, as well as a reduction of neointima/media ratio. (C, D).

Figure 2

Ki67-positive cells (arrows) within the neointima at 14 days after injury of a control animal. (A) Rosuvastatin treatment tended to reduce the proliferation index within the neointima (number of Ki67-positive cells/total amount of cells). However at day 14 no significant difference could be detected (p = 0.058). (B) Staining with immunofluorescence-labeled antibody against von Willebrand factor (secondary antibody alexa 594 in red) and _-smooth muscle actin in FITC (green) demonstrated that reendotheliazation was not completed 14 days after injury (arrow head) (_-smooth muscle actin in FITC, green). An adventitial artery is shown as a positive control (arrow). (C) Scale Bar = 100 μm.

Figure 3

Gelatinolytic activity assay demonstrated an induction of 92-kD gelatinase B three days after balloon injury in rat common carotid artery. No difference between rosuvastatin treated and controls could be detected (A). Western blot confirmed MMP-9 expression in rat common carotid arteries three days after balloon injury. No significant expression could be detected in non-injured contralateral arteries, which served as controls (B).