MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression by binding to target messenger RNAs (mRNAs), leading to translational repression or degradation. Here, we show that the miR-17approximately92 cluster is highly expressed in human endothelial cells and that miR-92a, a component of this cluster, controls the growth of new blood vessels (angiogenesis). Forced overexpression of miR-92a in endothelial cells blocked angiogenesis in vitro and in vivo. In mouse models of limb ischemia and myocardial infarction, systemic administration of an antagomir designed to inhibit miR-92a led to enhanced blood vessel growth and functional recovery of damaged tissue. MiR-92a appears to target mRNAs corresponding to several proangiogenic proteins, including the integrin subunit alpha5. Thus, miR-92a may serve as a valuable therapeutic target in the setting of ischemic disease.

Background— Stromal cell–derived factor-1α (SDF-1α) is implicated as a chemokine for endothelial progenitor cells (EPCs). We therefore hypothesized that SDF-1α gene transfer would induce therapeutic neovascularization in vivo by functioning as a chemokine of EPC. Methods and Results— To examine SDF-1α–induced mobilization of EPC, we used bone marrow–transplanted mice whose blood cells ubiquitously express β-galactosidase (LacZ). We produced unilateral hindlimb ischemia in the mice and transfected them with plasmid DNA encoding SDF-1α or empty plasmids into the ischemic muscles. SDF-1α gene transfer mobilized EPCs into the peripheral blood, augmented recovery of blood perfusion to the ischemic limb, and increased capillary density associated with partial incorporation of LacZ-positive cells into the capillaries of the ischemic limb, suggesting that SDF-1α induced vasculogenesis and angiogenesis. SDF-1α gene transfer did not affect ischemia-induced expression of vascular endothelial growth factor (VEGF) but did enhance Akt and endothelial nitric oxide synthase (eNOS) activity. Blockade of VEGF or NOS prevented all such SDF-1α–induced effects. Conclusions— SDF-1α gene transfer enhanced ischemia-induced vasculogenesis and angiogenesis in vivo through a VEGF/eNOS-related pathway. This strategy might become a novel chemokine therapy for next generation therapeutic neovascularization.

Abstract-Activated monocytes are present in the arterial walls of hypertensive patients and animals. Monocyte chemoattractant protein-1 (MCP-1), which controls monocyte function through its receptor (CCR2), is implicated in hypertensive inflammatory changes in the arterial wall. The role of CCR2 expression on monocytes in hypertensioninduced vascular remodeling, however, has not been addressed. We hypothesized that CCR2 on monocytes is critical in hypertension-induced vascular inflammation and remodeling. Hypertension was induced by infusion of angiotensin II (Ang II) into wild-type mice, CCR2-deficient (CCR2 Ϫ/Ϫ ) mice, and bone marrow-transferred mice with a leukocyte-selective CCR2 deficiency (BMT-CCR2 Ϫ/Ϫ ). In wild-type mice, Ang II increased CCR2 intensity in circulating monocytes, which was prevented by an Ang II type-1 (AT 1 ) receptor blocker or blunted in AT 1 receptor-deficient mice. Enhanced CCR2 intensity on monocytes was observed in hypertensive patients and rats, and was reduced by treatment with the Ang II receptor blocker, supporting the clinical relevance of the observation in mice. In CCR2Ϫ/Ϫ and BMT-CCR2 Ϫ/Ϫ mice, Ang II-induced vascular inflammation and vascular remodeling (aortic wall thickening and fibrosis) were blunted as compared with control mice. In contrast, Ang II-induced left ventricular hypertrophy developed in CCR2Ϫ/Ϫ and BMT-CCR2 Ϫ/Ϫ mice. The present study suggests that CCR2 expression in monocytes has a critical role in vascular inflammation and remodeling in Ang II-induced hypertension, and possibly in other forms of hypertension. Key Words: vascular remodeling Ⅲ angiotensin II Ⅲ inflammation Ⅲ leukocytes C hronic monocyte-mediated inflammation in arterial walls is observed in hypertensive patients and animals. [1][2][3] Recent clinical studies reported that lowering angiotensin II (Ang II) activity is a practical target of therapy for patients with cardiovascular disease. 4 -6 Ang II mediates reactive oxidative species (ROS) and stimulates the release of cytokines and growth factors (interleukin-6) and the expression of adhesion molecules (vascular cell adhesion molecule-1) and chemokines [monocyte chemoattractant protein-1 (MCP-1)] that mediate arterial wall inflammation. [1][2][3] For example, Ang II can induce monocyte chemotaxis by producing MCP-1 from vascular smooth muscle cells and monocytes through 8 MCP-1 is a C-C chemokine that controls monocyte recruitment to the site of inflammation through its receptor, C-C chemokine receptor (CCR) 2. 9 -11 The MCP-1/CCR2 pathway appears to be involved in the inflammatory aspect of hypertensive artery disease. MCP-1 and CCR2 expression and activity are enhanced in the arterial walls of hypertensive animals. 12,13 Furthermore, activation of the MCP-1/CCR2 pathway induces monocyte-mediated inflammation, as well as production of adhesion molecules, 14 inflammatory cytokines, 15 and tissue factor, 16 and stimulates migration of vascular smooth muscle cells, resulting in neointimal hyperplasia or atherosclerosis. [17][18][19][20] We...

Abstract-Angiotensin II (Ang II) is implicated in atherogenesis by activating inflammatory responses in arterial wall cells.Ang II accelerates the atherosclerotic process in hyperlipidemic apoEϪ/Ϫ mice by recruiting and activating monocytes. Monocyte chemoattractant protein-1 (MCP-1) controls monocyte-mediated inflammation through its receptor, CCR2. The roles of leukocyte-derived CCR2 in the Ang II-induced acceleration of the atherosclerotic process, however, are not known. We hypothesized that deficiency of leukocyte-derived CCR2 suppresses Ang II-induced atherosclerosis. Methods and Results-A bone marrow transplantation technique (BMT) was used to develop apoEϪ/Ϫ mice with and without deficiency of CCR2 in leukocytes (BMT-apoEϪ/ϪCCR2ϩ/ϩ and BMT-apoEϪ/ϪCCR2Ϫ/Ϫ mice). Compared with BMT-apoEϪ/ϪCCR2ϩ/ϩ mice, Ang II-induced increases in atherosclerosis plaque size and abdominal aortic aneurysm formation were suppressed in BMT-apoEϪ/ϪCCR2Ϫ/Ϫ mice. This suppression was associated with a marked decrease in monocyte-mediated inflammation and inflammatory cytokine expression. Conclusion-Leukocyte-derived CCR2 is critical in Ang II-induced atherosclerosis and abdominal aneurysm formation.The present data suggest that vascular inflammation mediated by CCR2 in leukocytes is a reasonable target of therapy for treatment of atherosclerosis. (Arterioscler Thromb Vasc Biol. 2003;24:e174-e178.)Key Words: atherosclerosis Ⅲ angiotensin II Ⅲ inflammation Ⅲ leukocytes C hronic inflammatory processes have an important role in atherosclerotic plaque progression, destabilization, and subsequent rupture/thrombosis, resulting in acute coronary syndrome. 1,2 Therefore, identification of the critical inflammatory pathway involved in atherosclerotic plaque progression and destabilization might aid in the development of novel therapeutic strategies to reduce atherothrombotic events.The renin-angiotensin system is now recognized as an important therapeutic target of atherosclerotic vascular disease. 3,4 Angiotensin II (Ang II) induces the production of reactive oxidative species and stimulates the expression of adhesion molecules (vascular cell adhesion molecule-1) and chemokines (monocyte chemoattractant protein-1 [MCP-1]). [3][4][5] Infusion of Ang II into hypercholesterolemic mice dramatically accelerates the atherosclerotic process, leading to the development of extensive atherosclerotic plaque formation and abdominal aortic aneurysm (AAA). 6,7 The Ang II-mediated acceleration of atherogenesis is characterized by the recruitment and activation of monocytes/macrophages and the degradation of elastin and collagen layers, suggesting that Ang II changes the lesion composition into a more destabilized phenotype. MCP-1 is a C-C chemokine that controls monocyte recruitment to the site of inflammation through its receptor, C-C chemokine receptor (CCR) 2. 8 -10 We recently demonstrated that blockade of the MCP-1 pathway by transfection of mutant MCP-1 gene limits Ang II-induced progression and destabilization of atherosclerotic 20 It is imposs...

Background— Therapeutic angiogenesis by delivery of vascular endothelial growth factor (VEGF) has attracted attention. However, the role and function of VEGF in experimental restenosis (neointimal formation) after vascular intraluminal injury have not been addressed. Methods and Results— We report herein that blockade of VEGF by soluble VEGF receptor 1 ( sFlt-1 ) gene transfer attenuated neointimal formation after intraluminal injury in rabbits, rats, and mice. sFlt-1 gene transfer markedly attenuated the early vascular inflammation and proliferation and later neointimal formation. sFlt-1 gene transfer also inhibited increased expression of inflammatory factors such as monocyte chemoattractant protein-1 and VEGF. Intravascular VEGF gene transfer enhanced angiogenesis in the adventitia but did not reduce neointimal formation. Conclusions— Increased expression and activity of VEGF are essential in the development of experimental restenosis after intraluminal injury by recruiting monocyte-lineage cells.