Ferulic acid augments angiogenesis via VEGF, PDGF and HIF-1 alpha.

Therapeutic angiogenesis is critical to wound healing and ischemic diseases such as myocardial infarction and stroke. For development of therapeutic agents, a search for new angiogenic agents is the key. Ferulic acid, a phytochemical found in many fruits and vegetables, exhibits a broad range of therapeutic effects on human diseases, including diabetes and cancer. This study investigated the augmenting effect of ferulic acid on angiogenesis through functional modulation of endothelial cells. Through endothelial cell migration and tube formation assays, ferulic acid (10(-6)-10(-4) M) was found to induce significant angiogenesis in human umbilical vein endothelial cells (HUVECs) in vitro without cytotoxicity. With chorioallantoic membrane assay, ferulic acid (10(-6)-10(-5) M) was also found to promote neovascularization in vivo. Using Western blot analysis and quantitative real-time polymerase chain reaction, we found that ferulic acid increased vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) expression in HUVECs. Furthermore, the amounts of hypoxic-induced factor (HIF) 1 alpha mRNA and protein, the major regulator of VEGF and PDGF, also showed up-regulation by ferulic acid. Electrophoretic migration shift assay showed that the binding activity of HIF-1 alpha was also enhanced with ferulic acid treatment of HUVECs. Moreover, inhibitors of extracellular-signal-regulated kinase 1/2 and phosphoinositide-3 kinase (PI3K) abolished the binding activity of HIF-1 alpha and the subsequent activation of VEGF and PDGF production by ferulic acid. Thus, both mitogen-activated protein kinase and PI3K pathways were involved in the angiogenic effects of ferulic acid. Taken together, ferulic acid serves as an angiogenic agent to augment angiogenesis both in vitro and in vivo. This effect might be observed through the modulation of VEGF, PDGF and HIF-1 alpha.

Lin CM ，Chiu JH ，Wu IH ，Wang BW ，Pan CM ，Chen YH ... -  《-》

A phosphodiesterase-5 inhibitor vardenafil enhances angiogenesis through a protein kinase G-dependent hypoxia-inducible factor-1/vascular endothelial growth factor pathway.

We examined whether phosphodiesterase-5 (PDE5) inhibition can promote ischemia-induced angiogenesis. Unilateral hindlimb ischemia was generated by resecting right femoral artery in wild-type C3H/He mice, treated with either vehicle or a PDE5 inhibitor vardenafil (10 mg/kg per day). Four weeks after surgery, vardenafil significantly enhanced blood flow recovery and augmented capillary collateral formation in ischemic muscle (blood flow ratios of ischemic/nonischemic leg: 0.52+/-0.17 [vehicle] versus 0.92+/-0.09 [vardenafil], P<0.01). Vardenafil upregulated protein expression of vascular endothelial growth factor and hypoxia-inducible factor (HIF)-1 alpha in ischemic muscle and enhanced mobilization of Sca-1/Flk-1-positive endothelial progenitor cells (EPCs) in peripheral blood and bone marrow, contributing to neovascularization. Vardenafil also promoted capillary-like tube formation of human umbilical vein endothelial cells and increased the number of human blood mononuclear cell-derived EPCs in vitro. Furthermore, reporter assays showed that vardenafil and cGMP activated the transactivation activity of HIF-1 under hypoxia. These effects of vardenafil were markedly inhibited by genetic ablation of endothelial nitric oxide synthase, a soluble guanylate cyclase inhibitor, and a protein kinase G inhibitor, respectively. Our results suggest that PDE5 inhibition enhances ischemia-induced angiogenesis with mobilization of EPCs through a protein kinase G-dependent HIF-1/vascular endothelial growth factor pathway. PDE5 inhibition may have a therapeutic potential to treat ischemic cardiovascular diseases.

Sahara M ，Sata M ，Morita T ，Nakajima T ，Hirata Y ，Nagai R ... -  《-》

Activation of fractalkine/CX3CR1 by vascular endothelial cells induces angiogenesis through VEGF-A/KDR and reverses hindlimb ischaemia.

The present study investigated the detailed mechanism by which fractalkine (Fkn), a CX3C chemokine, induces angiogenesis and its functional implication in alleviating ischaemia in vivo. Fkn induced new vessel formation on the excised rat aorta and chick chorioallantoic membrane (CAM) through CX3CR1 activation. Immunoblotting analysis, promoter assay and electrophoretic mobility shift assay showed that Fkn upregulated hypoxia-inducible factor-1 alpha (HIF-1alpha) by cultured human aortic endothelial cells (ECs), which in turn induced mRNA and protein levels of vascular endothelial growth factor (VEGF)-A through a p42/44 mitogen-activated protein kinase pathway. In vivo Fkn-induced angiogenesis on CAM was completely blocked by functional inhibition of VEGF receptor 2 kinase insert domain-containing receptor (KDR) and Rho GTPase. C57/BL6 mice with CX3CR1(-/-) bone marrow-derived cells developed angiogenesis in the implanted Fkn-mixed Matrigel plug, suggesting CX3CR1 activation in vascular ECs is sufficient for Fkn-induced angiogenesis in vivo. The condition of rat hindlimb ischaemia, which rapidly stimulated mRNA expression of both Fkn and VEGF-A, was significantly alleviated by the injection of whole-length Fkn protein. Fkn-induced activation of CX3CR1 by ECs leads to in vivo angiogenesis through two sequential steps: the induction of HIF-1alpha and VEGF-A gene expression by CX3CR1 activation and the subsequent VEGF-A/KDR-induced angiogenesis. The potent induction of angiogenesis by Fkn can be used as a therapeutic strategy for alleviating peripheral ischaemia.

Ryu J ，Lee CW ，Hong KH ，Shin JA ，Lim SH ，Park CS ，Shim J ，Nam KB ，Choi KJ ，Kim YH ，Han KH ... -  《CARDIOVASCULAR RESEARCH》

Diosgenin induces hypoxia-inducible factor-1 activation and angiogenesis through estrogen receptor-related phosphatidylinositol 3-kinase/Akt and p38 mitogen-activated protein kinase pathways in osteoblasts.

Yen ML ，Su JL ，Chien CL ，Tseng KW ，Yang CY ，Chen WF ，Chang CC ，Kuo ML ... -  《MOLECULAR PHARMACOLOGY》

Anti-angiogenic effects of ribonucleic acid interference targeting vascular endothelial growth factor and hypoxia-inducible factor-1alpha.

To compare the in vitro anti-angiogenic effects of inhibiting vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-alpha (HIF-1alpha) using ribonucleic acid (RNA) interference (RNAi). Laboratory investigation. VEGF or HIF-1alpha was antagonized in human retinal pigment epithelial (RPE) cells using RNAi, and then cells were cultured under hypoxia. Angiogenic proteins secreted into the media were measured using enzyme-linked immunosorbent assay. Media from hypoxic RPE cells was used to grow human umbilical vein endothelial cells (HUVECs). Capillary tube formation by HUVECs was quantified and compared to assess the effectiveness of angiogenesis. RNAi targeting VEGF caused a significant decrease in VEGF in addition to several other clinically important angiogenic factors, including angiogenin, interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and tumor growth factor beta(1) (TGF-beta(1)). Although HIF-1alpha RNAi reduced the production of VEGF, angiogenin, and TGF-beta(1), we observed an increase in the levels of several other angiogenic factors like IL-6, IL-8, and MCP-1. RNAi of VEGF and HIF-1alpha was effective in inhibiting angiogenesis, although the effect was more pronounced for VEGF RNAi. RNAi of VEGF and HIF-1alpha may have therapeutic potential in ischemic retinal diseases like diabetic retinopathy. Targeting VEGF seems to have the advantage of decreasing the production of several clinically important angiogenic factors, thereby effectively inhibiting angiogenesis. Antagonism of HIF-1alpha may lead to the overactivation of alternate transcription factors and their respective gene products, leading to less effective inhibition of angiogenesis.

Forooghian F ，Das B 《AMERICAN JOURNAL OF OPHTHALMOLOGY》