ABSTRACT
BACKGROUND: Pharmacological blockade of beta3-integrins inhibits neointimal lesion formation in nonmouse animal models of arterial injury. In contrast, beta3-integrin-deficient (beta3-/-) mice are not protected from neointimal lesion formation after arterial injury. We investigated this discrepancy in beta3-/- and wild-type (beta3+/+) mice using different models of injury. METHODS AND RESULTS: After disruption of the carotid with a transluminal probe, there was no significant difference in neointimal thickening between beta3-/- and beta3+/+ mice. However, after ligation of the carotid without medial disruption, there was reduced neointimal thickening in beta3-/- mice compared with beta3+/+ mice at intervals up to 3 months. Lesion reduction in beta3-/- mice was associated with fewer intimal smooth muscle cells (SMCs) without a difference in SMC apoptosis or proliferation rate compared with beta3+/+ mice, consistent with reduced SMC migration from the media into the intima of beta3-/- mice. Moreover, combined eccentric medial disruption and ligation of the carotid in beta3-/- mice resulted in neointimal lesion formation only at the site of medial disruption. Transplantation of bone marrow cells harvested from beta3+/+ mice into irradiated beta3-/- mice resulted in reduced neointimal lesion formation after carotid ligation injury, confirming the importance of alpha(v)beta3 and not alpha(IIb)beta3 in the attenuated response. CONCLUSIONS: The alpha(v)beta3-integrin mediates intimal SMC accumulation that contributes to neointimal thickening in the setting of arterial ligation.
Subject(s)
Carotid Arteries/pathology , Carotid Artery Injuries/pathology , Carotid Stenosis/etiology , Integrin alphaVbeta3/physiology , Integrin beta3/physiology , Tunica Intima/pathology , Animals , Apoptosis , Bone Marrow Transplantation , Carotid Arteries/metabolism , Carotid Arteries/surgery , Carotid Artery Injuries/etiology , Carotid Stenosis/metabolism , Carotid Stenosis/pathology , Cell Division , Cell Movement , Cells, Cultured/cytology , Cells, Cultured/metabolism , Chemotaxis , Disease Models, Animal , Hyperplasia , Integrin beta3/drug effects , Ligation , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Myocytes, Smooth Muscle/pathology , Platelet Glycoprotein GPIIb-IIIa Complex/physiology , Radiation Chimera , Stress, MechanicalABSTRACT
Although mice deficient in various genes are providing greater insight into the mechanisms of restenosis after angioplasty, there have been limitations with murine models not simulating human vascular disease. To develop a more clinically applicable model of primary atherosclerosis and restenosis following angioplasty of the primary lesion, we fed apolipoprotein E-deficient mice a Western diet and occluded the left common carotid artery for 2 days. Three weeks after flow was restored, the temporarily occluded carotids demonstrated atherosclerotic lesions containing foam cells, cholesterol clefts, necrotic cores, and fibrous capsules. The atherosclerotic carotids in other animals underwent angioplasty with a beaded probe, resulting in plaque and medial layer disruption. Three weeks after angioplasty, although there was significant neointimal lesion formation, the luminal narrowing did not change significantly secondary to overall vessel enlargement (positive remodeling). Neointimal lesions were composed of smooth-muscle cells and extracellular matrix observed adjacent to the original atherosclerotic plaques. Similarly, even at 3 months after the angioplasty the lumen was maintained despite greater neointimal lesion formation caused by progressive positive remodeling. This new murine model of primary atherosclerosis and postangioplasty intimal hyperplasia and remodeling mimics the human disease pattern of postangioplasty intimal hyperplasia. Used in transgenic animals, this model will likely facilitate understanding of the mechanisms of restenosis in humans.
