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1: Cardiovascular research, 2010 Aug 23,
VEGF-B gene transfer prevents angiotensin II-induced diastolic dysfunction via proliferation and capillary dilatation in rats.

[Abstract]Aims Heart growth and function are angiogenesis dependent, but little is known concerning the effects of key regulators of angiogenesis on diastolic heart failure. Here we tested the hypothesis that local vascular endothelial growth factor-B (VEGF-B) gene therapy prevents left ventricular diastolic dysfunction. Methods and Results Rats were subjected to pressure overload by infusing angiotensin II (33.3 mug/kg/h) for 2 weeks using osmotic minipumps. Intramyocardial delivery of adenoviral vector expressing VEGF-B(167A) improved angiotensin II-induced diastolic dysfunction compared to LacZ control virus. Local VEGF-B gene transfer increased mean capillary area in the left ventricle in control and angiotensin II-infused animals, while the density of capillaries was not affected. Interestingly, significant increases were noted in Ki67(+) proliferating cells, expression of interleukin1beta, and c-kit(+) cells in response to VEGF-B gene transfer. The increase in cardiac c-kit(+) cells was not associated with an induction of stromal cell-derived factor 1alpha, suggesting no mobilization of cells from bone marrow. Also, the phosphatidylinositol-3 kinase/Akt-pathway was activated. Conclusions VEGF-B gene transfer resulted in prevention of angiotensin II-induced diastolic dysfunction associated with induction of the Akt-pathway, increased proliferation and number of c-kit(+) cells as well as an increase in capillary area in left ventricle. VEGF-B may offer novel therapeutic possibilities for the prevention of the transition from compensated to decompensated cardiac hypertrophy and thereby for the treatment of heart failure.

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2: The Journal of biological chemistry, 2010 May 25, 635(1-3)
Structural insights into the binding of VEGF-B by VEGFR-1D2: Recognition and specificity.

[Abstract]The formation of blood vessels (angiogenesis) is a highly orchestrated sequence of events involving crucial receptor-ligand interactions. Angiogenesis is critical for physiological processes such as development, wound healing, reproduction, tissue regeneration and remodeling. It also plays a major role in sustaining tumor progression and chronic inflammation. Vascular Endothelial Growth Factor-B (VEGF-B), a member of the VEGF family of angiogenic growth factors, effects blood vessel formation by binding to a tyrosine kinase receptor, VEGFR-1. There is growing evidence of the important role played by VEGF-B in physiological and pathological vasculogenesis. Development of VEGF-B antagonists, which inhibit the interaction of this molecule with its cognate receptor, would be important for the treatment of pathologies associated specifically with this growth factor. In this study we present the crystal structure of the complex of VEGF-B with domain 2 of VEGFR-1 at 2.7A resolution. Our analysis reveals that each molecule of the ligand engages two receptor molecules using two symmetrical binding sites. Based on these interactions we identify the receptor-binding determinants on VEGF-B and shed light on the differences in specificity towards VEGFR-1 among the different VEGF homologs.

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3: European journal of pharmacology, 2010 Mar 18,
Heme oxygenase-1 and carbon monoxide promote neovascularization after myocardial infarction by modulating the expression of HIF-1alpha, SDF-1alpha and VEGF-B.

[Abstract]Heme oxygenase-1 (HO-1), a known cytoprotective enzyme implicated also in the cell cycle regulation and angiogenesis, exerts many of its beneficial effects through carbon monoxide (CO). We studied the roles of HO-1 and CO in cardiac regeneration after myocardial infarction. Prior to coronary artery ligation, male Wistar rats were given either cobolt protoporphyrin IX to induce HO-1 or CO-donor methylene chloride. Cardiac regeneration was assessed by immunohistochemistry and confocal microscopy. CO significantly increased the accumulation of c-kit+stem/progenitor cells into the infarct area and induced formation of new coronary arteries by promoting a substantial differentiation of c-kit+cells into vascular smooth muscle cells (c-kit+/GATA6+ cells). Furthermore, CO increased proliferation of cardiomyocytes in the infarct border area at 4 weeks post-infarction. This suggests proliferation of newly formed cardiomyocytes derived from c-kit+cells as 10% of c-kit+cells expressed early cardiac marker Nkx2.5. Increased expression of hypoxia-inducible factor-1alpha( (HIF-1alpha), stromal cell derived factor-1alpha (SDF-1alpha) and vascular endothelial growth factor-B (VEGF-B) were found in the infarct areas of CO-donor pretreated hearts suggesting that these factors potentially promoted the migration of c-kit+cells into the infarct area and subsequent vasculogenesis and myocardial regeneration by CO. HO-1 increased both capillary and vascular densities, while only a small increase of c-kit+cells was found. HO-1 upregulated SDF-1alpha, but did not have effect on HIF-1alpha and VEGF-B. In conclusion, HO-1 and CO have differential roles and mechanisms of action in cardiac regeneration. Modulation of the HO-1/CO axis may provide a novel tool for the repair of cardiac injury.

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4: Nature, 2010 Mar 14,
Vascular endothelial growth factor B controls endothelial fatty acid uptake.

[Abstract]The vascular endothelial growth factors (VEGFs) are major angiogenic regulators and are involved in several aspects of endothelial cell physiology. However, the detailed role of VEGF-B in blood vessel function has remained unclear. Here we show that VEGF-B has an unexpected role in endothelial targeting of lipids to peripheral tissues. Dietary lipids present in circulation have to be transported through the vascular endothelium to be metabolized by tissue cells, a mechanism that is poorly understood. Bioinformatic analysis showed that Vegfb was tightly co-expressed with nuclear-encoded mitochondrial genes across a large variety of physiological conditions in mice, pointing to a role for VEGF-B in metabolism. VEGF-B specifically controlled endothelial uptake of fatty acids via transcriptional regulation of vascular fatty acid transport proteins. As a consequence, Vegfb(-/-) mice showed less uptake and accumulation of lipids in muscle, heart and brown adipose tissue, and instead shunted lipids to white adipose tissue. This regulation was mediated by VEGF receptor 1 and neuropilin 1 expressed by the endothelium. The co-expression of VEGF-B and mitochondrial proteins introduces a novel regulatory mechanism, whereby endothelial lipid uptake and mitochondrial lipid use are tightly coordinated. The involvement of VEGF-B in lipid uptake may open up the possibility for novel strategies to modulate pathological lipid accumulation in diabetes, obesity and cardiovascular diseases.

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5: Circulation, 2009 Feb 17, 119(6)
Vascular endothelial growth factor-B induces myocardium-specific angiogenesis and arteriogenesis via vascular endothelial growth factor receptor-1- and neuropilin receptor-1-dependent mechanisms.

[Abstract]BACKGROUND: New revascularization therapies are urgently needed for patients with severe coronary heart disease who lack conventional treatment options. METHODS AND RESULTS: We describe a new proangiogenic approach for these no-option patients using adenoviral (Ad) intramyocardial vascular endothelial growth factor (VEGF)-B186 gene transfer, which induces myocardium-specific angiogenesis and arteriogenesis in pigs and rabbits. After acute infarction, AdVEGF-B186 increased blood vessel area, perfusion, ejection fraction, and collateral artery formation and induced changes toward an ischemia-resistant myocardial phenotype. Soluble VEGF receptor-1 and soluble neuropilin receptor-1 reduced the effects of AdVEGF-B186, whereas neither soluble VEGF receptor-2 nor inhibition of nitric oxide production had this result. The effects of AdVEGF-B186 involved activation of neuropilin receptor-1, which is highly expressed in the myocardium, via recruitment of G-protein-alpha interacting protein, terminus C (GIPC) and upregulation of G-protein-alpha interacting protein. AdVEGF-B186 also induced an antiapoptotic gene expression profile in cardiomyocytes and had metabolic effects by inducing expression of fatty acid transport protein-4 and lipid and glycogen accumulation in the myocardium. CONCLUSIONS: VEGF-B186 displayed strikingly distinct effects compared with other VEGFs. These effects may be mediated at least in part via a G-protein signaling pathway. Tissue-specificity, high efficiency in ischemic myocardium, and induction of arteriogenesis and antiapoptotic and metabolic effects make AdVEGF-B186 a promising candidate for the treatment of myocardial ischemia.

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6: Nature reviews. Cancer, 2008 Dec, 8(12)
FLT1 and its ligands VEGFB and PlGF: drug targets for anti-angiogenic therapy?

[Abstract]Less than 5 years ago, it was still not clear whether anti-angiogenic drugs would prove successful in the clinic. After numerous patients with cancer or age-related macular degeneration have been treated with these drugs, they have now become part of the standard range of therapeutic tools. Despite this milestone, anti-angiogenic therapy still faces a number of clinical hurdles, such as improving efficacy, avoiding escape and resistance, and minimizing toxicity. Hopefully, other agents with complementary mechanisms, such as those that target placental growth factor, will offer novel opportunities for improved treatment.

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7: Circulation research, 2008 Oct 24, 103(9)
Overexpression of vascular endothelial growth factor-B in mouse heart alters cardiac lipid metabolism and induces myocardial hypertrophy.

[Abstract]Vascular endothelial growth factor (VEGF)-B is poorly angiogenic but prominently expressed in metabolically highly active tissues, including the heart. We produced mice expressing a cardiac-specific VEGF-B transgene via the alpha-myosin heavy chain promoter. Surprisingly, the hearts of the VEGF-B transgenic mice showed concentric cardiac hypertrophy without significant changes in heart function. The cardiac hypertrophy was attributable to an increased size of the cardiomyocytes. Blood capillary size was increased, whereas the number of blood vessels per cell nucleus remained unchanged. Despite the cardiac hypertrophy, the transgenic mice had lower heart rate and blood pressure than their littermates, and they responded similarly to angiotensin II-induced hypertension, confirming that the hypertrophy does not compromise heart function. Interestingly, the isolated transgenic hearts had less cardiomyocyte damage after ischemia. Significantly increased ceramide and decreased triglyceride levels were found in the transgenic hearts. This was associated with structural changes and eventual lysis of mitochondria, resulting in accumulation of intracellular vacuoles in cardiomyocytes and increased death of the transgenic mice, apparently because of mitochondrial lipotoxicity in the heart. These results suggest that VEGF-B regulates lipid metabolism, an unexpected function for an angiogenic growth factor.

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8: Arteriosclerosis, thrombosis, and vascular biology, 2008 Sep, 28(9)
VEGF-B taken to our hearts: specific effect of VEGF-B in myocardial ischemia.

[Abstract]Vascular endothelial growth factor (VEGF)-B is poorly angiogenic but prominently expressed in metabolically highly active tissues, including the heart. We produced mice expressing a cardiac-specific VEGF-B transgene via the alpha-myosin heavy chain promoter. Surprisingly, the hearts of the VEGF-B transgenic mice showed concentric cardiac hypertrophy without significant changes in heart function. The cardiac hypertrophy was attributable to an increased size of the cardiomyocytes. Blood capillary size was increased, whereas the number of blood vessels per cell nucleus remained unchanged. Despite the cardiac hypertrophy, the transgenic mice had lower heart rate and blood pressure than their littermates, and they responded similarly to angiotensin II-induced hypertension, confirming that the hypertrophy does not compromise heart function. Interestingly, the isolated transgenic hearts had less cardiomyocyte damage after ischemia. Significantly increased ceramide and decreased triglyceride levels were found in the transgenic hearts. This was associated with structural changes and eventual lysis of mitochondria, resulting in accumulation of intracellular vacuoles in cardiomyocytes and increased death of the transgenic mice, apparently because of mitochondrial lipotoxicity in the heart. These results suggest that VEGF-B regulates lipid metabolism, an unexpected function for an angiogenic growth factor.