The aim of the present study was to investigate the effect of removal of the adventitia on vascular remodeling and vasoconstriction of the carotid artery in New Zealand rabbit. Adventitia of carotid artery was removed mechanically. The histology, morphology and reactivity of the carotid artery was observed by immunohistochemistry and measurement of carotid ring tension immediately, 1 week and 2 weeks after removal of the adventitia. No damage of intima and media was observed after removing the adventitia. Removal of the adventitia caused a remarkable proliferation of the vascular media and formed the neointima. Compared with the control ring, norepinephrine (NE)-induced vasocontraction in adventitia-denuded carotid artery was significantly reduced immediately and 1 week after the operation (P<0.05). Adventitia removal promoted the neointima formation and decreased vasoconstriction of the carotid artery, indicating that the adventitia is involved in the regulation of vascular remodeling and vasoconstriction.
Animals ; Carotid Arteries ; pathology ; physiology ; surgery ; Connective Tissue ; physiology ; surgery ; Muscle, Smooth, Vascular ; pathology ; Rabbits ; Tunica Intima ; pathology ; Vasoconstriction ; physiology

We examined whether alterations in vascular endothelial function and early structural changes in atherosclerosis are associated with microvascular complications in patients with type 1 diabetes mellitus (DM). Flow-mediated dilation (FMD) of the brachial artery and carotid intima-media thickness (IMT) measurement were performed in 70 young adults (aged 19 to 35 yr), 48 with type 1 DM, and 22 normal controls. Patients with diabetes had a lower peak FMD response (7.8+/-3.9 vs. 11.1 +/-1.9%, p<0.001) and increased IMT (0.51+/-0.10 vs. 0.42+/-0.07 mm, p<0.001) compared with controls. Twenty (41.7%) of the patients had microvascular complications including neuropathy, nephropathy, or retinopathy. In these complicated diabetic patients, we found a lower FMD response (6.1+/-2.5 vs. 9.9+/-3.5%, p=0.001) compared with diabetics without microvascular complications. The presence of microvascular complications was also associated with older age and longer duration of the disease. However, no differences were observed in IMT, body size, blood pressure, HbA1c, C-reactive protein, low-density lipoprotein or high-density lipoprotein cholesterol levels between complicated and non-complicated patients. Endothelial dysfunction and early structural atherosclerotic changes are common manifestations in type 1 DM, and endothelial dysfunction is thought to be an early event in the atherosclerotic process and important in the pathogenesis of microvascular complications.
Adult ; Diabetes Mellitus, Type 1/*complications ; Diabetic Angiopathies/*etiology ; Endothelium, Vascular/*physiology ; Female ; Humans ; Male ; *Microcirculation ; Tunica Intima/pathology ; Tunica Media/pathology ; Vasodilation

Retinoic acids may inhibit vascular smooth muscle cell proliferation, but may promote endothelial cell proliferation in cell culture. However, little data are available about the effects of all-trans-retinoic acid (ATRA) on endothelial regeneration and functional recovery in an experimental model of vascular injury. Accordingly, we investigated whether ATRA may attenuate neointima formation and accelerate endothelial regeneration with functional recovery in balloon-injured rat aorta. Twelve-week-old male Sprague-Dawley rats underwent endothelial denudation of the thoracic aorta by balloon injury. Fourteen rats were fed a standard rat pellet diet. Another 14 rats were fed ATRA (1.5 mg/day) for 2 weeks. The animals were killed on day 14 for organ chamber study and morphometric analysis. Rats in the ATRA group had a significantly improved acetylcholine-induced relaxation response than those in control group. However, endothelial independent response was not significantly different between the two groups. The extent of reendothelialization was markedly superior in the ATRA group compared with control group (p>0.05). Furthermore, neointima area and the ratio of neointima to medial area were significantly less in ATRA group than in control group (p>0.05). In conclusion, ATRA may accelerate endothelial regeneration with functional recovery, and attenuate neointima formation in balloon-injured rat aorta.
Acetylcholine/pharmacology ; Animal ; Aorta, Thoracic/physiology ; Aorta, Thoracic/injuries ; Aorta, Thoracic/drug effects* ; Balloon Dilatation/adverse effects ; Endothelium, Vascular/physiology ; Endothelium, Vascular/drug effects ; Male ; Muscle Relaxation/physiology ; Muscle Relaxation/drug effects ; Muscle, Smooth, Vascular/physiology ; Muscle, Smooth, Vascular/drug effects ; Rats ; Rats, Sprague-Dawley ; Regeneration/physiology ; Regeneration/drug effects ; Tretinoin/pharmacology* ; Tunica Intima/physiology ; Tunica Intima/pathology* ; Tunica Intima/drug effects* ; Vasodilator Agents/pharmacology

BACKGROUNDVascular remodeling is an important pathologic process in vascular injury for various vascular disorders such as atherosclerosis, postangioplasty restenosis and transplant arteriopathy. Recently, pathologic change and the role of bone marrow derived cells were wildly studied in atherosclerosis and restenosis. But the manner of lesion formation in neointima and cell recruitment in vascular remodeling lesion in the present of hypercholesterolemia is not yet fully understood.

METHODSDouble-transgenic mice knockout of LDL receptor gene (LDL -/-) and expressing ubiquitously green fluorescent protein (GFP) were obtained by cross-breeding LDL -/- mice with the GFP-expressing transgenic mice. LDL -/- mice (22 - 24 weeks of age) fed high fat diet containing 1.25% (w/w) cholesterol were subjected to 9Gy irradiation and received bone marrow (BM) cells from the double-transgenic mice. Four weeks later, a nonconstrictive cuff was placed around the right femoral artery. After another 2 weeks, both right and left femoral arteries were harvested and subjected to histochemical analysis. Apoptosis was analyzed in situ using TUNEL assay.

RESULTSTwo weeks after cuff placement, atherosclerotic lesions developed in the intima consisting of a massive accumulation of foam cells. The tissue stained with anti-alpha smooth muscle actin (SMA) antibody, showed a number of SMA-positive cells in the intimal lesion area. They were also positive for GFP, indicating that BM-derived cells can differentiate to SMCs in the intima in cuff-induced vascular remodeling lesions. Numerous small vessels in the adventitia as well as the endothelial lining of the intima were positive both for CD31 and GFP. The intima and media showed a large number of TUNEL-positive signals after 2 weeks cuff injury, indicating the presence of apoptosis in vascular remodeling.

CONCLUSIONSAtherosclerotic lesions in mice can be developed in the intima after 2 weeks of cuff-induced vascular injury under the hypercholesterolemic conditions. Our data also clearly indicate that bone marrow-derived cells differentiated to smooth muscles and endothelial cells in the formation of these lesions in the presence of hypercholesterolemia.

Animals ; Apoptosis ; Atherosclerosis ; pathology ; Bone Marrow Cells ; cytology ; Cell Differentiation ; Cell Movement ; Endothelial Cells ; pathology ; Female ; Hematopoietic Stem Cells ; pathology ; Mice ; Mice, Inbred C57BL ; Muscle, Smooth, Vascular ; pathology ; Receptors, LDL ; physiology ; Tunica Intima ; pathology ; Tunica Media ; pathology

OBJECTIVETo investigate the mechanism of a novel angiotensin II type 1 receptor-associated protein (ATRAP) interfering with angiotensin II type 1 (AT1) receptor-mediated vascular smooth muscle cell (VSMC) growth and neointimal formation.

METHODSVSMCs isolated from thoracic aorta of adult Sprague-Dawley (SD) rats were used in this study. ATRAP cDNA was subcloned into pcDNA3 vector and then transfected into VSMCs. DNA synthesis and extracellular signal-regulated kinase (ERK) and phospho-ERK expressions in VSMCs were assayed by measurement of 3H thymidine incorporation and Western blotting, respectively. Morphological changes were observed in the balloon injured artery with or without transfection of ATRAP cDNA using 12-week-old male SD rats.

RESULTSATRAP overexpression in VSMCs inhibited angiotensin II (Ang II)-induced 3H thymidine incorporation 48 hours after Ang II stimulation (P < 0.05). In VSMC, Ang II stimulation increased the phosphorylation of ERK, which reached the peak around 60 minutes. The activation of phospho-ERK was significantly decreased by ATRAP (P < 0.05). Neointimal formation was markedly inhibited by ATRAP overexpression in injuried arteries.

CONCLUSIONSThe AT1 receptor-derived activation of ERK plays an essential role in Ang II-induced VSMC growth. The growth inhibitory effects of ATRAP might be due to interfering with AT1 receptor-mediated activation of ERK in VSMC growth and neointimal formation.

Angiotensin II ; pharmacology ; Animals ; Aorta, Thoracic ; cytology ; Cell Division ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Male ; Muscle, Smooth, Vascular ; cytology ; physiology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; physiology ; Receptors, Angiotensin ; genetics ; physiology ; Transfection ; Tunica Intima ; cytology

OBJECTIVETo observe the histopathological changes of a novel small-caliber vascular graft after implantation in canine theca interna under scanning electron microscope.

METHODA 3 cm segment of the vascular graft (diameter of 4 mm) was implanted in an end-to-end fashion to bridge the severed carotid artery in 19 healthy dogs. Color Doppler sonography was performed 2 weeks after the operation to observe the patency rate of artificial blood vessel. At 1, 8, 12 and 24 week postimplantation, the arteries (4, 4, 6 and 5, respectively) were collected for optical and scanning electron microscopies after angiography to observe the patency of the arteries.

RESULTSOf the total of 19 arteries, occlusion occurred in 1 at 12 weeks and 1 at 24 weeks. Optical and electron microscopies showed that 1 week after implantation, slight fibroplasias and formation of red thrombus could be seen at the vascular anastomosis without endothelial cell lining. At 8 weeks, the host tissue grew into the lumen of the graft through the pores to form uniform neointima consisting of plenty of collagen fibers, but still without endothelial cells. At 12 weeks, discontinuous endothelial cells were seen to grow on the surface of the neointima. In the middle segment of the vascular graft, immature endothelial cells were found to grow in clusters. The structure of the neointima was loose in comparison with that at the anastomosis, with occasional inflammation cells. Twenty-four weeks after grafting, endothelial cells grew over the entire inner wall of the patent graft, and the surface of the neointima at the anastomosis was lined with continuous endothelial cells.

CONCLUSIONThe vascular graft can be useful for reconstruction of canine carotid artery defect and achieves good endothelialization 24 weeks after implantation.

Animals ; Blood Vessel Prosthesis ; Blood Vessel Prosthesis Implantation ; methods ; Carotid Arteries ; diagnostic imaging ; physiology ; surgery ; Collagen ; metabolism ; Dogs ; Endothelial Cells ; cytology ; metabolism ; ultrastructure ; Microscopy, Electron, Scanning ; Models, Animal ; Time Factors ; Tunica Intima ; cytology ; metabolism ; ultrastructure ; Ultrasonography, Doppler, Color ; Vascular Patency

Vascular remodeling is being recognized as a fundamental process during atherosclerosis and restenosis. Cumulative studies have demonstrated that extracellular matrix (ECM) degrading enzymes play a critical role during vascular remodeling. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family is a recently identified metalloproteinase family which also has capacity to degrade ECM. ADAMTS family consists of 19 members and has been linked to a variety of physiological processes including development, angiogenesis, coagulation etc. Aberrant expression or function of ADAMTS members have been implicated to many disease states such as arthritis, cancer, thrombocytopenic purpura, but barely described with regard to cardiovascular disease. This review summarizes the recent advance with respect to the role of ADAMTS-7 in vascular remodeling. We review the structure, tissue distribution, substrate, expression and regulation of ADAMTS-7, especially highlight the fine tune by ADAMTS-7 of its substrate cartilage oligomeric matrix protein (COMP) in maintaining vascular homeostasis. By use of rat carotid artery balloon injury model to mimic vascular injury in vivo, we found that ADAMTS-7 protein was accumulated preferentially in neointima and mainly localized in vascular smooth muscle cells (VSMCs). Adenovirus-elicited ADAMTS-7 overexpression greatly accelerated VSMCs migration and proliferation both in vivo and in vitro, and subsequently aggravated neointima thickening post-injury. Conversely, siRNA-mediated ADAMTS-7 knock down bona fide inhibited VSMCs migration and proliferation in cultured VSMCs and injured arteries, and ultimately ameliorated neointima area. Further studies demonstrated that ADAMTS-7 facilitated VSMCs migration through degradation of its substrate COMP. Moreover, we elucidated that COMP has the capacity to maintain the contractile phenotype of VSMCs through interacting with integrin alpha7beta1. ADAMTS-7 may therefore serve as a novel therapeutic target for atherosclerosis and postangioplasty restenosis.
ADAM Proteins ; physiology ; ADAMTS7 Protein ; Animals ; Atherosclerosis ; physiopathology ; Carotid Artery Injuries ; metabolism ; pathology ; Cartilage Oligomeric Matrix Protein ; Cell Movement ; Cell Proliferation ; Extracellular Matrix Proteins ; metabolism ; physiology ; Glycoproteins ; physiology ; Humans ; Matrilin Proteins ; Muscle, Smooth, Vascular ; metabolism ; pathology ; Rats ; Tunica Intima ; metabolism ; pathology

OBJECTIVETo investigate the neointima formation and the expression of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) in cuff-induced vascular injury in mouse model, and to examine the effect of angiotensin II type 1 receptor (AT1) blocker, olmesartan, on MCP-1 and TNF-alpha expression and consequently vascular remodeling.

METHODSVascular injury was induced by polyethylene cuff-placement around the mouse femoral artery. Some mice were treated with AT1 receptor blocker, olmesartan, at the dose of 3 mg.kg(-1).day(-1) with an osmotic minipump. Neointima formation and the proliferation of vascular smooth muscle cells (VSMCs) were measured by morphometric analysis and bromodeoxyuridine (BrdU) incorporation. MCP-1 and TNF-alpha expression was detected by Western blot and immunohistochemical staining.

RESULTSWe observed neointima formation 14 days after cuff placement as well as VSMCs proliferation in the media and neointima. Cuff placement also induced MCP-1 and TNF-alpha expression in the media and neointima that the VSMCs specifically existed. Treatment of mice with olmesartan at a dose of 3 mg.kg(-1).day(-1), which did not influence systolic blood pressure, significantly decreased neointima formation and the proliferation of VSMCs. Olmesartan also inhibited MCP-1 and TNF-alpha expression in the injured arteries.

CONCLUSIONSOur results demonstrate that blockade of AT1 receptor inhibits MCP-1 and TNF-alpha expression and thereby improves vascular remodeling.

Analysis of Variance ; Animals ; Blotting, Western ; Cell Division ; drug effects ; physiology ; Cells, Cultured ; Chemokine CCL2 ; analysis ; Disease Models, Animal ; Imidazoles ; pharmacology ; Immunohistochemistry ; Male ; Mice ; Mice, Inbred C57BL ; Monocytes ; cytology ; drug effects ; Muscle, Smooth, Vascular ; cytology ; drug effects ; Neovascularization, Physiologic ; drug effects ; physiology ; Olmesartan Medoxomil ; Probability ; Sensitivity and Specificity ; Tetrazoles ; pharmacology ; Tumor Necrosis Factor-alpha ; analysis ; drug effects ; Tunica Intima ; drug effects ; pathology ; Vascular Diseases ; physiopathology

OBJECTIVETo investigate the effect of interferon regulatory factors (IRFs) on neointimal formation after vascular injury in the mouse, and its possible mechanism.

METHODSVascular injury was induced by polyethylene cuff placement around the left femoral artery of IRF-1-deficient mice and C57BL/6J mice. The mRNA expressions of IRF-1, IRF-2, angiotensin II type 2 (AT2) receptor, interleukin-1 beta converting enzyme (ICE), inducible nitric oxide synthase (iNOS) were detected by RT-PCR and immunohistochemical staining.

RESULTSNeointimal formation after vascular injury was significantly greater in IRF-1-deficient mice than that in C57BL/6J mice (P<0.05). In contrast, TUNEL-positive nuclei to total nuclei in the neointima and media in vascular smooth muscle cell (VSMC) in the injured artery significantly attenuated in IRF-1-deficient mice compared to C57BL/6J mice (P<0.05). The expressions of AT2 receptor as well as pro-apoptotic genes such as ICE and iNOS in C57BL/6J mice were up-regulated in response to vascular injury, but this upregulation was attenuated in IRF-1-deficient mice.

CONCLUSIONSOur results suggest that IRF-1 induces VSMC apoptosis and inhibits neointimal formation after vascular injury at least partly due to the upregulation of AT2 receptor, ICE and iNOS expressions. These results indicate that IRF-1 exerts an inhibitory effect on neointimal formation through the induction of apoptosis in VSMCs.

Animals ; Apoptosis ; physiology ; Caspase 1 ; genetics ; metabolism ; Femoral Artery ; anatomy & histology ; pathology ; Interferon Regulatory Factor-1 ; genetics ; metabolism ; Interferon Regulatory Factor-2 ; genetics ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Muscle, Smooth, Vascular ; cytology ; metabolism ; pathology ; Nitric Oxide Synthase Type II ; genetics ; metabolism ; Platelet Endothelial Cell Adhesion Molecule-1 ; genetics ; metabolism ; Receptor, Angiotensin, Type 2 ; genetics ; metabolism ; Tunica Intima ; pathology ; physiology