Vascular endothelial growth factor B, a novel growth factor for endothelial cells

Structural basis for VEGF-C binding to neuropilin-2 and sequestration by a soluble splice form

Vascular endothelial growth factor C (VEGF-C) is a potent lymphangiogenic cytokine that signals via the coordinated action of two cell surface receptors, Neuropilin-2 (Nrp2) and VEGFR-3. Diseases associated with both loss and gain of VEGF-C function, lymphedema and cancer, respectively, motivate studies of VEGF-C/Nrp2 binding and inhibition. Here, we demonstrate that VEGF-C binding to Nrp2 is regulated by C-terminal proteolytic maturation. The structure of the VEGF-C C terminus in complex with the ligand binding domains of Nrp2 demonstrates that a cryptic Nrp2 binding motif is released upon proteolysis, allowing specific engagement with the b1 domain of Nrp2. Based on the identified structural requirements for Nrp2 binding to VEGF-C, we hypothesized that the endogenous secreted splice form of Nrp2, s9Nrp2, may function as a selective inhibitor of VEGF-C. We find that s9Nrp2 forms a stable dimer that potently inhibits VEGF-C/Nrp2 binding and cellular signaling. These data provide critical insight into VEGF-C/Nrp2 binding and inhibition.

Expression of vascular endothelial growth factor in oral squamous cell carcinoma

OBJECTIVES

The goal of this study was to determine the correlation of clinicopathological factors and the up-regulation of vascular endothelial growth factor (VEGF) expression in oral squamous cell carcinoma.

MATERIALS AND METHODS

Immunohistochemical staining of VEGF and quantitative real-time polymerase chain reaction (RT-PCR) of VEGF mRNA were performed in 20 specimens from 20 patients with oral squamous cell carcinoma and another 20 specimens from 20 patients with carcinoma in situ as a controlled group.

RESULTS

The results were as follows: 1) In immunohistochemical study of poorly differentiated and invasive oral squamous cell carcinoma, high-level staining of VEGF was observed. Significant correlation was observed between immunohistochemical VEGF expression and histologic differentiation, tumor size of specimens (Pearson correlation analysis, significance r>0.6, P<0.05). 2) In VEGF quantitative RT-PCR analysis, progressive cancer showed more VEGF expression than carcinoma in situ. Paired-samples analysis determined the difference of VEGF mRNA expression level between cancer tissue and carcinoma in situ tissue, between T1 and T2-4 (Student's t-test, P<0.05).

CONCLUSION

These findings suggest that up-regulation of VEGF may play a role in the angiogenesis and progression of oral squamous cell carcinoma.

Binding of VEGF-A is sufficient to abrogate the disturbing effects of VEGF-B together with VEGF-A on retinal endothelial cells

Purpose

Inhibition of vascular endothelial growth factor (VEGF) is a promising strategy to treat retinal complications of diabetes. In contrast to VEGF-A binding ranibizumab, aflibercept also binds to other members of the VEGF family including VEGF-B, but potential effects of this factor on permeability and angiogenic processes are unclear. Therefore, we studied how VEGF-B variants as single agents or together with VEGF-A₁₆₅ might affect proliferation, migration, or barrier function of retinal endothelial cells (REC). Also investigated was the normalization of REC properties with both VEGF-inhibitors to explore if additional targeting of VEGF-B is relevant.

Methods

Stimulation of proliferation or migration of immortalized bovine REC (iBREC) and disturbance of their barrier by exposure to VEGF-B variants (as single factors or together with VEGF-A₁₆₅) was determined with or without VEGF-binding proteins being added. Permeability of iBREC was assessed by measuring their transendothelial resistance (TER) and expression of the tight junction protein claudin-1.

Results

VEGF-B₁₆₇ and VEGF-B₁₈₆ enhanced proliferation of iBREC but these isoforms did not affect cell migration. Interestingly, ranibizumab completely blocked both migration and proliferation induced by VEGF-A plus VEGF-B. Both VEGF-B variants did also not affect barrier function or claudin-1 expression in a normal or high-glucose environment. Accordingly, binding VEGF-A was enough to normalize a reduced TER and reinstate claudin-1 lost during treatment with this factor in combination with VEGF-B.

Conclusions

Important properties and functions of REC seem not to be affected by any VEGF-B variant and targeting the key factor VEGF-A is sufficient to normalize growth factor-disturbed cells of this type.

Electronic supplementary material

The online version of this article (doi:10.1007/s00417-015-2944-z) contains supplementary material, which is available to authorized users.

Multi-omic integrated networks connect DNA methylation and miRNA with skeletal muscle plasticity to chronic exercise in Type 2 diabetic obesity

Epigenomic regulation of the transcriptome by DNA methylation and posttranscriptional gene silencing by miRNAs are potential environmental modulators of skeletal muscle plasticity to chronic exercise in healthy and diseased populations. We utilized transcriptome networks to connect exercise-induced differential methylation and miRNA with functional skeletal muscle plasticity. Biopsies of the vastus lateralis were collected from middle-aged Polynesian men and women with morbid obesity (44 kg/m(2) ± 10) and Type 2 diabetes before and following 16 wk of resistance (n = 9) or endurance training (n = 8). Longitudinal transcriptome, methylome, and microRNA (miRNA) responses were obtained via microarray, filtered by novel effect-size based false discovery rate probe selection preceding bioinformatic interrogation. Metabolic and microvascular transcriptome topology dominated the network landscape following endurance exercise. Lipid and glucose metabolism modules were connected to: microRNA (miR)-29a; promoter region hypomethylation of nuclear receptor factor (NRF1) and fatty acid transporter (SLC27A4), and hypermethylation of fatty acid synthase, and to exon hypomethylation of 6-phosphofructo-2-kinase and Ser/Thr protein kinase. Directional change in the endurance networks was validated by lower intramyocellular lipid, increased capillarity, GLUT4, hexokinase, and mitochondrial enzyme activity and proteome. Resistance training also lowered lipid and increased enzyme activity and caused GLUT4 promoter hypomethylation; however, training was inconsequential to GLUT4, capillarity, and metabolic transcriptome. miR-195 connected to negative regulation of vascular development. To conclude, integrated molecular network modelling revealed differential DNA methylation and miRNA expression changes occur in skeletal muscle in response to chronic exercise training that are most pronounced with endurance training and topographically associated with functional metabolic and microvascular plasticity relevant to diabetes rehabilitation.

Matrix density alters zyxin phosphorylation, which limits peripheral process formation and extension in endothelial cells invading 3D collagen matrices

This study was designed to determine the optimal conditions required for known pro-angiogenic stimuli to elicit successful endothelial sprouting responses. We used an established, quantifiable model of endothelial cell (EC) sprout initiation where ECs were tested for invasion in low (1 mg/mL) and high density (5 mg/mL) 3D collagen matrices. Sphingosine 1-phosphate (S1P) alone, or S1P combined with stromal derived factor-1α (SDF) and phorbol ester (TPA), elicited robust sprouting responses. The ability of these factors to stimulate sprouting was more effective in higher density collagen matrices. S1P stimulation resulted in a significant increase in invasion distance, and with the exception of treatment groups containing phorbol ester, invasion distance was longer in 1mg/mL compared to 5mg/mL collagen matrices. Closer examination of cell morphology revealed that increasing matrix density and supplementing with SDF and TPA enhanced the formation of multicellular structures more closely resembling capillaries. TPA enhanced the frequency and size of lumen formation and correlated with a robust increase in phosphorylation of p42/p44 Erk kinase, while S1P and SDF did not. Also, a higher number of significantly longer extended processes formed in 5mg/mL compared to 1mg/mL collagen matrices. Because collagen matrices at higher density have been reported to be stiffer, we tested for changes in the mechanosensitive protein, zyxin. Interestingly, zyxin phosphorylation levels inversely correlated with matrix density, while levels of total zyxin did not change significantly. Immunofluorescence and localization studies revealed that total zyxin was distributed evenly throughout invading structures, while phosphorylated zyxin was slightly more intense in extended peripheral processes. Silencing zyxin expression increased extended process length and number of processes, while increasing zyxin levels decreased extended process length. Altogether these data indicate that ECs integrate signals from multiple exogenous factors, including changes in matrix density, to accomplish successful sprouting responses. We show here for the first time that zyxin limited the formation and extension of fine peripheral processes used by ECs for matrix interrogation, providing a molecular explanation for altered EC responses to high and low density collagen matrices.

Vascular Endothelial Growth Factor-B in Physiology and Disease

Vascular endothelial growth factor-B (VEGF-B), discovered over 15 years ago, has long been seen as one of the more ambiguous members of the VEGF family. VEGF-B is produced as two isoforms: one that binds strongly to heparan sulfate in the pericellular matrix and a soluble form that can acquire binding via proteolytic processing. Both forms of VEGF-B bind to VEGF-receptor 1 (VEGFR-1) and the neuropilin-1 (NRP-1) coreceptor, which are expressed mainly in blood vascular endothelial cells. VEGF-B-deficient mice and rats are viable without any overt phenotype, and the ability of VEGF-B to induce angiogenesis in most tissues is weak. This has been a puzzle, as the related placenta growth factor (PlGF) binds to the same receptors and induces angiogenesis and arteriogenesis in a variety of tissues. However, it seems that VEGF-B is a vascular growth factor that is more tissue specific and can have trophic and metabolic effects, and its binding to VEGFR-1 shows subtle but important differences compared with that of PlGF. VEGF-B has the potential to induce coronary vessel growth and cardiac hypertrophy, which can protect the heart from ischemic damage as well as heart failure. In addition, VEGF-B is abundantly expressed in tissues with highly active energy metabolism, where it could support significant metabolic functions. VEGF-B also has a role in neuroprotection, but unlike other members of the VEGF family, it does not have a clear role in tumor progression. Here we review what is hitherto known about the functions of this growth factor in physiology and disease.

Resveratrol plays dual roles in pancreatic cancer cells

PURPOSE

Although the potential anticancer effect of resveratrol (RSV) on pancreatic cancer has been reported, its mechanism was not fully understood. The role of vascular endothelial growth factor B (VEGF-B) in cancer remains controversial. Herein, we aimed to examine whether the anticancer effect of RSV was related to the VEGF-B.

METHODS

The effect of RSV on pancreatic cancer cell line (capan-2 cells) was evaluated by CCK-8 assay, Hoechst 33342 staining, and flow cytometry. The mRNA level of VEGF-B was measured by real-time PCR. VEGF-B expression was knockdown by small interfering RNA (siRNA).The protein levels of VEGF-B, glycogen synthase kinase-3 beta (GSK-3β), and Bax were measured by Western blot.

RESULTS

Resveratrol treatment inhibited tumor growth, induced apoptosis, and up-regulated Bax expression in capan-2 cells. The mRNA and protein levels of VEGF-B were up-regulated after RSV treatment. However, VEGF-B siRNA treatment increased the apoptotic rate, and inhibited tumor activator GSK-3β, while Bax expression was not affected. The combination of RSV and VEGF-B siRNA showed significantly higher apoptotic rate in comparison with RSV or VEGF-B siRNA mono-treatment group.

CONCLUSIONS

Resveratrol plays dual roles in pancreatic cancer: as a tumor suppressor via the up-regulation of Bax; as a tumor activator via the up-regulation of VEGF-B; and the anticancer effect of RSV is much stronger than the cancer promotion effect. The combination of RSV with pharmacological inhibitor of VEGF-B might, therefore, be a promising modality for clinical pancreatic cancer therapy.

De novo hem- and lymphangiogenesis by endothelial progenitor and mesenchymal stem cells in immunocompetent mice

Cellular pro-angiogenic therapies may be applicable for the treatment of peripheral vascular diseases. Interactions between mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) may provide such a treatment option. With the exception of some studies in man, experiments have only been performed in immunodeficient mice and rats. We studied an immunocompetent syngeneic mouse model. We isolated MSCs from bone marrow and EPCs from the lung of adult C57/Bl.6 mice and co-injected them in Matrigel subcutaneously in adult C57/Bl.6 mice. We demonstrate development of both blood vessels and lymphatics. Grafted EPCs integrated into the lining of the two vessel types, whereas MSCs usually did not incorporate into the vessel wall. Injections of each separate cell type did not, or hardly, reveal de novo angiogenesis. The release of VEGF-A by MSCs has been shown before, but its inhibitors, e.g., soluble VEGF receptors, have not been studied. We performed qualitative and quantitative studies of the proteins released by EPCs, MSCs, and cocultures of the cells. Despite the secretion of VEGF inhibitors (sVEGFR-1, sVEGFR-2) by EPCs, VEGF-A was secreted by MSCs at bioavailable amounts (350 pg/ml). We confirm the secretion of PlGF, FGF-1, MCP-1, and PDGFs by EPCs/MSCs and suggest functions for VEGF-B, amphiregulin, fractalkine, CXCL10, and CXCL16 during MSC-induced hem- and lymphangiogenesis. We assume that lymphangiogenesis is induced indirectly by growth factors from immigrating leukocytes, which we found in close association with the lymphatic networks. Inflammatory responses to the cellular markers GFP and cell-tracker red (CMPTX) used for tracing of EPCs or MSCs were not observed. Our studies demonstrate the feasibility of pro-angiogenic/lymphangiogenic therapies in immunocompetent animals and indicate new MSC/EPC-derived angiogenic factors.

Application of stem cell/growth factor system, as a multimodal therapy approach in regenerative medicine to improve cell therapy yields

Stem cells hold a great promise for regenerative medicine, especially for replacing cells in infarcted organ that hardly have any intrinsic renewal capacity, including heart and brain. Signaling pathways that regulate pluripotency or lineage-specific gene and protein expression have been the major focus of stem cell research. Between them, there are some well known signaling pathways such as GF/GFR systems, SDF-1α/CXC4 ligand receptor interaction and PI3K/Akt signaling, and cytokines may regulate cell fate decisions, and can be utilized to positively influence cell therapy outcomes or accentuate synergistic compliance. For example, contributing factors in the progression of heart failure are both the loss of cardiomyocytes after myocardial infarction, and the absence of an adequate endogenous repair signaling. Combining cell engraftment with therapeutic signaling factor delivery is more exciting in terms of host progenitor/donor stem cell survival and proliferation. Thus stem cell-based therapy, besides triggering signaling pathways through GF/GFR systems can become a realistic option in regenerative processes for replacing lost cells and reconstituting the damaged organ, as before.

Vascular endothelial growth factor receptor 1 expression in nasal polyp tissue

BACKGROUND

Edema represents a key feature of nasal polyp (NP) disease. Members of the vascular endothelial growth factor (VEGF) family may be involved, but the precise role of VEGF-A, VEGF-B, placental growth factor (PlGF), and their receptors VEGFR1 and VEGFR2 in NP edema formation remains elusive.

OBJECTIVE

Exploring the expression of VEGF family members and their receptors and their correlation with clinical, radiological, and edema markers in NP.

METHODS

The expression of VEGF-A, VEGF-B, PlGF, VEGFR1, and VEGFR2 was measured in NP (n = 23) and control tissue (n = 22) at mRNA and protein level. Edema was evaluated by measuring albumin levels and wet/dry ratios. Computed tomography (CT) scans were scored using the Lund-Mackay scoring system. IL-5 mRNA expression was determined by real-time RT-PCR. Cell suspensions from NP (n = 10) and control tissue (n = 12) were stimulated in vitro with IL-1β or TNFα.

RESULTS

mRNA expression of VEGFR1 and VEGF-B was significantly higher in NP compared with control tissue. Expression levels of VEGF-B and VEGFR1 significantly correlated with NP albumin content (VEGF-B: P = 0.0208; VEGFR1: P = 0.0293), CT scan scores (VEGF-B: P = 0.0075; VEGFR1: P = 0.0068), and IL-5 mRNA (VEGF-B: P = 0.0027; VEGFR1: P = 0.0001). In vitro stimulation of control and NP tissue cell suspensions with IL-1β or TNFα significantly reduced the expression of VEGFR2 in control tissue, without altering VEGFR1 and VEGF-B expression. hVEGF-B induced nitric oxide production in NP macrophages (P < 0.05).

CONCLUSION

Expression levels of VEGFR1 and VEGF-B correlate with edema and clinical markers of NP disease and therefore represent potential therapeutic targets.

Development of the hemochorial maternal vascular spaces in the placenta through endothelial and vasculogenic mimicry

The maternal vasculature within the placenta in primates and rodents is unique because it is lined by fetal cells of the trophoblast lineage and not by maternal endothelial cells. In addition to trophoblast cells that invade the uterine spiral arteries that bring blood into the placenta, other trophoblast subtypes sit at different levels of the vascular space. In mice, at least five distinct subtypes of trophoblast cells have been identified which engage maternal endothelial cells on the arterial and venous frontiers of the placenta, but which also form the channel-like spaces within it through a process analogous to formation of blood vessels (vasculogenic mimicry). These cells are all large, post-mitotic trophoblast giant cells. In addition to assuming endothelial cell-like characteristics (endothelial mimicry), they produce dozens of different hormones that are thought to regulate local and systemic maternal adaptations to pregnancy. Recent work has identified distinct molecular pathways in mice that regulate the morphogenesis of trophoblast cells on the arterial and venous sides of the vascular circuit that may be analogous to specification of arterial and venous endothelial cells.

VEGF-B-induced vascular growth leads to metabolic reprogramming and ischemia resistance in the heart

Angiogenic growth factors have recently been linked to tissue metabolism. We have used genetic gain- and loss-of function models to elucidate the effects and mechanisms of action of vascular endothelial growth factor-B (VEGF-B) in the heart. A cardiomyocyte-specific VEGF-B transgene induced an expanded coronary arterial tree and reprogramming of cardiomyocyte metabolism. This was associated with protection against myocardial infarction and preservation of mitochondrial complex I function upon ischemia-reperfusion. VEGF-B increased VEGF signals via VEGF receptor-2 to activate Erk1/2, which resulted in vascular growth. Akt and mTORC1 pathways were upregulated and AMPK downregulated, readjusting cardiomyocyte metabolic pathways to favor glucose oxidation and macromolecular biosynthesis. However, contrasting with a previous theory, there was no difference in fatty acid uptake by the heart between the VEGF-B transgenic, gene-targeted or wildtype rats. Importantly, we also show that VEGF-B expression is reduced in human heart disease. Our data indicate that VEGF-B could be used to increase the coronary vasculature and to reprogram myocardial metabolism to improve cardiac function in ischemic heart disease.

Subject Categories Cardiovascular System; Metabolism

See also: C Kupatt and R Hinkel (March 2014)

Endothelial fatty acid transport: role of vascular endothelial growth factor B

Dietary lipids present in the circulation have to be transported through the vascular endothelium to be utilized by tissue cells, a vital mechanism that is still poorly understood. Vascular endothelial growth factor B (VEGF-B) regulates this process by controlling the expression of endothelial fatty acid transporter proteins (FATPs). Here, we summarize research on the role of the vascular endothelium in nutrient transport, with emphasis on VEGF-B signaling.

Tumor associated macrophage: a review on the phenotypes, traits and functions

The macrophages role within the tumor microenvironment has amended by a variety of factors, thus serves a vital role in tissue morphogenesis. The role of macrophages in health and disease differs enormously as the macrophage has shown dual functions. Macrophage has a basic role in antigen presentation serving as the first line of defense in diseases. However the presence of cytokines and growth factors, both together have regulated the macrophage to become negative effectors promoting tumor activity. Hence macrophages are a double edged weapon, and any imbalance in the regulatory mechanisms caused a shift from tumoricidal to tumorigenic activities. TAMs would be the main reason of the invasion in tumor microenvironment enhancing as well as tumor invasion, angiogenesis and metastasis promoting tumor genesis. Macrophages are the multifunctional cells which have conducted by the tumor cells to produce tumor promoting factors that enable the stimulation of angiogenesis, and tumor cell invasion. This fact has resulted initiation or promotion of tumor genesis, where the tumor has progressed to an upper malignant stage. The present review has focused on the tumor associated macrophages and their roles in tumor genesis.

Vascular endothelial growth factor in acute lung injury and acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is the most severe form of lung injury, characterised by alveolar oedema and vascular permeability, in part due to disruption of the alveolar capillary membrane integrity. Vascular endothelial growth factor (VEGF) was originally identified as a vascular permeability factor and has been implicated in the pathogenesis of acute lung injury/ARDS. This review describes our current knowledge of VEGF biology and summarises the literature investigating the potential role VEGF may play in normal lung maintenance and in the development of lung injury.

Phylogenetic analysis and positive-selection site detecting of vascular endothelial growth factor family in vertebrates

Vascular endothelial growth factor (VEGF), known to play an important role in vascular homeostasis, vascular integrity and angiogenesis, is little known about the evolutionary relationship of its five members especially the role of gene duplication and natural selection in the evolution of the VEGF family. In this study, seventy-five full-length cDNA sequences from 33 vertebrate species were extracted from the NCBI's GenBank, UniProt protein database and the Ensembl database. By phylogenetic analyses, we investigated the origin, conservation, and evolution of the VEGFs. Five VEGF family members in vertebrates might be formed by gene duplication. The inferred evolutionary transitions that separate members which belong to different gene clusters correlated with changes in functional properties. Selection analysis and protein structure analysis were combined to explain the relationship of the site-specific evolution in the vertebrate VEGF family. Eleven positive selection sites, one transmembrane region and the active sites were detected in this process.

Antiangiogenic effects of marine sponge derived compounds on cancer

The term "angiogenic switch" refers to a time-restricted event during tumor progression where the balance between pro- and anti-angiogenic factors, resulting in the transition from dormant avascularized hyperplasia to outgrowing vascularized tumor and eventually to malignant tumor progression. Targeting angiogenesis and its mechanistic pathways are critical target for cancer therapy. Recently, marine derived compounds, plays major role in cancer research. Several sponge derived compounds such as alkaloids, terpenes, macrocylic lactone and polyketide are leading drugs in the treatment of different types of diseases including cancer. Those marine sponge compounds inhibit cancer cell proliferation and tumor angiogenesis. Hence, this review sheds light on angiogenic regulators and marine sponge derived antiangiogenic compounds for cancer.

Gene and protein therapies utilizing VEGF for ALS

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that is usually fatal within 2-5years. Unfortunately, the only treatment currently available is riluzole, which has a limited efficacy. As a redress, there is an expanding literature focusing on other potential treatments. One such potential treatment option utilizes the vascular endothelial growth factor (VEGF) family, which includes factors that are primarily associated with angiogenesis but are now increasingly recognized to have neurotrophic effects. Reduced expression of a member of this family, VEGF-A, in mice results in neurodegeneration similar to that of ALS, while treatment of animal models of ALS with either VEGF-A gene therapy or VEGF-A protein has yielded positive therapeutic outcomes. These basic research findings raise the potential for a VEGF therapy to be translated to the clinic for the treatment of ALS. This review covers the VEGF family, its receptors and neurotrophic effects as well as VEGF therapy in animal models of ALS and advances towards clinical trials.

Angiogenesis and hematological malignancies

Since the initial hypotheses on the importance of angiogenesis in the pathogenesis of cancer approximately 30 years ago, there have been major advances in the understanding of the cellular and molecular mechanisms involved in the regulation of this complex process of new vessel formation. Among the multitude of factors, vascular endothelial growth factor (VEGF) has emerged as one of the most potent angiogenic factors, being implicated in the initiation of signal transduction responsible for cell proliferation, survival, migration and adhesion. Inhibition of VEGF and its signaling pathway offers a potential new molecular target in cancer therapy. This article reviews the role of angiogenesis and its mediators, particularly vascular endothelial growth factors, in hematological malignancies, as well as the potential use of anti-angiogenic therapies in the management of these conditions.

The role of platelet-derived growth factor in the pathogenesis of sinonasal polyps: immunohistochemical assessment in epithelial, subepithelial and deep layers of the mucosa

OBJECTIVES

The aim of this study is to investigate the role of platelet-derived growth factor (PDGF) in the pathogenesis of sinonasal polyps.

METHODS

Study group (groups 1-3) consisted of nasal polyp samples of patients with sinonasal polyps and the control group consisted of inferior turbinate samples of patients without nasal polyp. In group 1, 14 specimens from ethmoid sinus; in group 2, 10 specimens from nasal cavity; in group 3, 10 specimens from maxillary sinus; and in group 4 (control), 9 specimens from inferior turbinate were included. By immunohistochemical staining technique, the PDGF positivity index (PI) in mucosal layers and in the inflammatory cells were assessed at the epithelium (EP), subepithelial layer of lamina propria (SE), and deep paraglandular layer of the mucosa (D).

RESULTS

Polymorphonuclear cell (PMNC)-percentage (%) values of ethmoid and maxillary sinus, and the PDGF PI from all cells of ethmoid sinus and nasal cavity were significantly higher than those of the control group. As mononuclear cell-% (MNC-%) increased, the PDGF_EP_basal PI, PDGF_SE_endothelial PI, and PDGF_D_endothelial PI decreased. As PMNC-PDGF PI increased, the PDGF_D_perivascular PI decreased and PDGF_D_endothelial PI increased. As PDGF-MNC PI increased, the PDGF_EP_apical PI, PDGF_SE_endothelial PI, and PDGF_D_endothelial PI decreased. As PDGF-all cells (PMNCs, MNCs, and fibroblasts) PI increased, the PDGF_EP_basal PI and PDGF_D_endothelial PI decreased, and the PDGF_D_perivascular PI increased.

CONCLUSION

We concluded that the PDGF systems play important roles in polyp pathogenesis. Fibroblast-derived PDGF may be more important than MNC-derived PDGF in polyp developing process. Increased perivascular-PDGF-PI in deep layers of the mucosa may result in sinonasal polyp formation by causing an increase in vascular permeability and extracellular edema, and thus promoting migration of inflammatory cells to extracellular area. Tissue oxygenization may be important for the initiation of PDGF release system. Because of this reason, nasal obstruction should be medically treated earlier, and, if necessary, by surgical approaches.

Targeting angiogenesis and the tumor microenvironment

The role of the microenvironment during the initiation and progression of malignancy is appreciated to be of critical importance for improved molecular diagnostics and therapeutics. The tumor microenvironment is the product of a crosstalk between different cells types. Active contribution of tumor-associated stromal cells to cancer progression has been recognized. Stromal elements consist of the extracellular matrix, fibroblasts of various phenotypes, and a scaffold comprised of immune and inflammatory cells, blood and lymph vessels, and nerves. This review focuses on therapeutic targets in the microenvironment related to tumor endothelium, tumor associated fibroblasts, and the extracellular matrix.

Vascular endothelial growth factor in heart failure

Heart failure is a devastating condition, the progression of which culminates in a mismatch of oxygen supply and demand, with limited options for treatment. Heart failure has several underlying causes including, but not limited to, ischaemic heart disease, valvular dysfunction, and hypertensive heart disease. Dysfunctional blood vessel formation is a major problem in advanced heart failure, regardless of the aetiology. Vascular endothelial growth factor (VEGF) is the cornerstone cytokine involved in the formation of new vessels. A multitude of investigations, at both the preclinical and clinical levels, have garnered valuable information on the potential utility of targeting VEGF as a treatment option for heart failure. However, clinical trials of VEGF gene therapy in patients with coronary artery disease or peripheral artery disease have not, to date, demonstrated clinical benefit. In this Review, we outline the biological characterization of VEGF, and examine the evidence for its potential therapeutic application, including the novel concept of VEGF as adjuvant therapy to stem cell transplantation, in patients with heart failure.

Science Signaling Podcast: 2 July 2013

Domain swapping experiments reveal how two related VEGF ligands trigger distinct biological outcomes by binding to the same receptor.

A microRNA signature defines chemoresistance in ovarian cancer through modulation of angiogenesis

Epithelial ovarian cancer is the most lethal gynecologic malignancy; it is highly aggressive and causes almost 125,000 deaths yearly. Despite advances in detection and cytotoxic therapies, a low percentage of patients with advanced stage disease survive 5 y after the initial diagnosis. The high mortality of this disease is mainly caused by resistance to the available therapies. Here, we profiled microRNA (miR) expression in serous epithelial ovarian carcinomas to assess the possibility of a miR signature associated with chemoresistance. We analyzed tumor samples from 198 patients (86 patients as a training set and 112 patients as a validation set) for human miRs. A signature of 23 miRs associated with chemoresistance was generated by array analysis in the training set. Quantitative RT-PCR in the validation set confirmed that three miRs (miR-484, -642, and -217) were able to predict chemoresistance of these tumors. Additional analysis of miR-484 revealed that the sensitive phenotype is caused by a modulation of tumor vasculature through the regulation of the VEGFB and VEGFR2 pathways. We present compelling evidence that three miRs can classify the response to chemotherapy of ovarian cancer patients in a large multicenter cohort and that one of these three miRs is involved in the control of tumor angiogenesis, indicating an option in the treatment of these patients. Our results suggest, in fact, that blockage of VEGF through the use of an anti-VEGFA antibody may not be sufficient to improve survival in ovarian cancer patients unless VEGFB signaling is also blocked.

Brain homeostasis: VEGF receptor 1 and 2-two unequal brothers in mind

Vascular endothelial growth factors (VEGFs), initially thought to act specifically on the vascular system, exert trophic effects on neural cells during development and adulthood. Therefore, the VEGF system serves as a promising therapeutic target for brain pathologies, but its simultaneous action on vascular cells paves the way for harmful side effects. To circumvent these deleterious effects, many studies have aimed to clarify whether VEGFs directly affect neural cells or if the effects are mediated secondarily via other cell types, like vascular cells. A great number of reports have shown the expression and function of VEGF receptors (VEGFRs), mainly VEGFR-1 and -2, in neural cells, where VEGFR-2 has been described as the major mediator of VEGF-A signals. This review aims to summarize and compare the divergent roles of VEGFR-1 and -2 during CNS development and homeostasis.

Interaction of monocytes/macrophages with ovarian cancer cells promotes angiogenesis in vitro

It has been established that macrophages and endothelial cells infiltrate peritoneum in the vicinity of tumor implants of epithelial ovarian cancer (EOC). This study investigates whether the interaction of ovarian cancer cells and tumor-associated macrophages could promote the involvement of endothelial cells in angiogenesis. Macrophage phenotypes were detected by fluorescence-activated cell sorting, and cytokine/chemokine secretion was measured by enzyme linked immunosorbent assay. The effect of co-culture of ovarian cancer cells and tumor-associated macrophage (TAM) cells on endothelial cell migration and tube formation was investigated. Signaling pathway mediators were also evaluated for their potential roles in endothelial cell activation by ovarian cancer cells co-cultured with TAM cells. Our results showed that higher expression of interleukin-8 (IL-8) expression associated with 54.26 ± 34.46% of TAM infiltration of peritoneum was significantly higher than 16.58 ± 17.74% of CD3(+) T-cell by immunofluorescence co-staining and confocal microscopy. THP-1 cells exhibited M2-polarized phenotype markers with high proportion of CD68(+) , CD206(+) and CD204(+) markers after phorbol 12-myristate 13-acetate (PMA) treatment, After co-culturing with TAM cells in a transwell chamber system, EOC cells (SKOV3) increased their IL-8 expression at the level of mRNA and protein. After exposure to the conditioned medium obtained by co-culturing TAM and SKOV3 cells, the migration and tube formation of endothelial cells were enhanced significantly. Furthermore, the upregulation of IL-8 expression in ovarian cancer cells induced by macrophages could be inhibited by pyrollidine dithiocarbamate, an inhibitor of nuclear factor (NF)- κB signal pathway. We suggest that the interaction of ovarian cancer cells and tumor-associated macrophages enhances the ability of endothelial cells to promote the progression of ovarian cancer.

Diabetic retinopathy and VEGF

Diabetic retinopathy remains the leading vascular-associated cause of blindness throughout the world. Its treatment requires a multidisciplinary interventional approach at both systemic and local levels. Current management includes laser photocoagulation, intravitreal steroids, and anti-vascular endothelial growth factor (VEGF) treatment along with systemic blood sugar control. Anti-VEGF therapies, which are less destructive and safer than laser treatments, are being explored as primary therapy for the management of vision-threatening complications of diabetic retinopathy such as diabetic macular edema (DME). This review provides comprehensive information related to VEGF and describes its role in the pathogenesis of diabetic retinopathy, and in addition, examines the mechanisms of action for different antiangiogenic agents in relation to the management of this disease. Medline (Pubmed) searches were carried out with keywords “VEGF”, “diabetic retinopathy”, and “diabetes” without any year limitation to review relevant manuscripts used for this article.

Both Kdr and Flt1 play a vital role in hypoxia-induced Src-PLD1-PKCγ-cPLA(2) activation and retinal neovascularization

To understand the mechanisms of Src-PLD1-PKCγ-cPLA2 activation by vascular endothelial growth factor A (VEGFA), we studied the role of Kdr and Flt1. VEGFA, while having no effect on Flt1 phosphorylation, induced Kdr phosphorylation in human retinal microvascular endothelial cells (HRMVECs). Depletion of Kdr attenuated VEGFA-induced Src-PLD1-PKCγ-cPLA2 activation. Regardless of its phosphorylation state, downregulation of Flt1 also inhibited VEGFA-induced Src-PLD1-PKCγ-cPLA2 activation, but only modestly. In line with these findings, depletion of either Kdr or Flt1 suppressed VEGFA-induced DNA synthesis, migration, and tube formation, albeit more robustly with Kdr downregulation. Hypoxia induced tyrosine phosphorylation of Kdr and Flt1 in mouse retina, and depletion of Kdr or Flt1 blocked hypoxia-induced Src-PLD1-PKCγ-cPLA2 activation and retinal neovascularization. VEGFB induced Flt1 tyrosine phosphorylation and Src-PLD1-PKCγ-cPLA2 activation in HRMVECs. Hypoxia induced VEGFA and VEGFB expression in retina, and inhibition of their expression blocked hypoxia-induced Kdr and Flt1 activation, respectively. Furthermore, depletion of VEGFA or VEGFB attenuated hypoxia-induced Src-PLD1-PKCγ-cPLA2 activation and retinal neovascularization. These findings suggest that although VEGFA, through Kdr and Flt1, appears to be the major modulator of Src-PLD1-PKCγ-cPLA2 signaling in HRMVECs, facilitating their angiogenic events in vitro, both VEGFA and VEGFB mediate hypoxia-induced Src-PLD1-PKCγ-cPLA2 activation and retinal neovascularization via activation of Kdr and Flt1, respectively.

GnRH analogues in the prevention of ovarian hyperstimulation syndrome

The GnRH analogue (agonist and antagonist GnRH) changed ovarian stimulation. On the one hand, it improved chances of pregnancy to obtain more oocytes and better embryos. This leads to an ovarian hyper-response, which can be complicated by the ovarian hyperstimulation syndrome (OHSS). On the other hand, the GnRH analogue can prevent the incidence of OHSS: GnRH antagonist protocols, GnRH agonist for triggering final oocyte maturation, either together or separately, coasting, and the GnRH analogue may prove useful for avoiding OHSS in high-risk patients. We review these topics in this article.

Emerging VEGF-receptor inhibitors for colorectal cancer

INTRODUCTION

Targeted agents have dramatically improved and enriched the therapeutical choices for patients with metastatic colorectal cancer (mCRC). By better understanding the role of the angiogenic pathway in colorectal cancer (CRC), new therapies have been developed. Bevacizumab, the first anti-angiogenetic agent approved for the treatment of mCRC provide a proof of concept since it has improved the progression-free survival and overall survival when combined with cytotoxic chemotherapy.

AREAS COVERED

This review is focused on the most recent findings on the VEGF signaling pathway and new therapeutic drugs explored in clinical trials.

EXPERT OPINION

Despite the advantage offered by bevacizumab, the median overall survival of mCRC patient exceeds 21 months; thus, investigational efforts are needed. Several antiangiogenic agents for the treatment of mCRC are being tested in preclinical and clinical Phase I/II trials. Unfortunately a discrete number of Phase III trials produced negative results. Recently aflibercept and regorafenib, two new antiangiogenic drugs, have been approved as the new-targeted agents for the treatment of mCRC, according to the positive findings from the VELOUR and the CORRECT studies. In order to maximize clinical impact it will be important to validate predictive biomarkers and best combination treatments to offer for mCRC patients; further research and intense investigation is still required.

Are epsins a therapeutic target for tumor angiogenesis?

Solid tumor growth requires the formation of new blood vessels to supply nutrients and oxygen to the malignant cells; one approach to cancer therapy is to block this process by inhibiting VEGF signaling. In this issue of the JCI, Pasula et al. demonstrate a surprising role of epsins--proteins involved in endocytosis--in tumor angiogenesis via their modulation of VEGF signaling. Their findings suggest that these proteins might represent a new target for the development of cancer therapeutics.

Targeted therapy for metastatic colorectal cancer: role of aflibercept

Worldwide, colorectal cancer (CRC) is the third most commonly diagnosed cancer in male individuals and the second most commonly diagnosed cancer in female individuals. Survival outcomes are less than optimal for patients with metastatic disease, with a 5-year survival in the 5% to 8% range. The development of new chemotherapeutic agents and effective combination regimens for metastatic colorectal cancer (mCRC) has increased median overall survival (OS) to the 24- to 28-month range. Because of the recognition that vascular endothelial growth factors (VEGFs) and their receptors are primary regulators of physiologic and pathologic angiogenesis and lymphangiogenesis, leading to neovascularization and tumor growth, the targeting of the angiogenic pathway has become a focus of key therapeutic strategies in mCRC. Therapeutic regimens that include bevacizumab, an inhibitor of VEGF-A, in combination with cytotoxic chemotherapy, have resulted in improved response rate (RR) and survival in mCRC. However, the effects of VEGF-A inhibition are often temporary, with resistance and disease progression developing in most patients. Proposed models include intrinsic and adaptive resistance, mediated by factors other than VEGF-A. Aflibercept (known as ziv-aflibercept in the United States; Zaltrap®, Regeneron Pharmaceuticals; sanofi-aventis), a novel recombinant fusion protein, is an angiogenic factor trap that blocks the binding of VEGF-A, VEGF-B, and placental growth factor. Phase I/II clinical trials have demonstrated effective activity in mCRC, with acceptable safety and tolerability. A recent phase III randomized double-blind trial in patients previously treated with oxaliplatin reported significant improvement in OS, progression-free survival (PFS), and RR with aflibercept compared with placebo when administered in combination with irinotecan and fluorouracil. Adverse events were consistent with anti-VEGF therapy. Thus aflibercept represents a potential new treatment option for patients with mCRC.

Angiogenesis in metastatic colorectal cancer and the benefits of targeted therapy

The diverse pathways and molecules involved in angiogenesis, the formation of new blood vessels, have been targeted for the treatment of colorectal and other cancers. Vascular endothelial growth factor (VEGF)-A binding to VEGF receptor (VEGFR)-2 is believed to be the key signaling pathway mediating angiogenesis. Other VEGF pathways involved in angiogenesis include VEGF-A, VEGF-B, and placental growth factor binding to VEGFR-1, and VEGF-C and VEGF-D binding to VEGFR-2 and VEGFR-3. VEGF signaling also intersects with other pathways, including angiopoietin/Tie, Notch, hypoxia-inducible factor, and integrin pathways. The roles of these pathways in tumor angiogenesis and in various human cancers will be explored in this article. In addition, preclinical and clinical data on bevacizumab, aflibercept (known as ziv-aflibercept in the US), and investigational antiangiogenic agents in development for the treatment of colorectal and other cancers will be reviewed.

Assessing the in vivo efficacy of biologic antiangiogenic therapies

PURPOSE

To review key clinical issues underlying the assessment of in vivo efficacy when using antiangiogenic therapies for cancer treatment.

METHODS

Literature relevant to use of antiangiogenic therapies in cancer was reviewed, with particular emphasis on the assessment of in vivo efficacy of these agents, as well as additional angiogenic factors that could play a role in escape from angiogenesis inhibition.

RESULTS

In order to grow and metastasize, tumors need to continually acquire new blood supplies; therefore, therapeutic inhibition of angiogenesis has become a component of anticancer treatment for many tumor types. Bevacizumab, a humanized monoclonal antibody directed at vascular endothelial growth factor A (VEGF-A), has shown activity in combination with chemotherapy in metastatic colorectal cancer. Nevertheless, the use of antiangiogenic therapies remains suboptimal; specifically, optimal dose, duration of therapy, and combination of agents remain unknown. Also, at present, it is not possible to determine which patients are most likely to respond to a given form of antiangiogenic therapy. There has been increased recognition of alternative pathways possibly associated with disease progression in patients undergoing antiangiogenic therapy targeted at VEGF-A. Multiligand-targeted antiangiogenic therapies, such as ziv-aflibercept (formerly known as aflibercept, VEGF Trap), are currently undergoing clinical evaluation. Ziv-aflibercept forms monomeric complexes with VEGF-A, VEGF-B, and PlGF, which have a long half-life, allowing optimization of ziv-aflibercept doses and angiogenic blockage.

CONCLUSIONS

Although antiangiogenic therapies have increased treatment options for cancer patients, their use is limited by a lack of established and standardized methodology to evaluate their efficacy in vivo. Circulating endothelial cells, hypertension, and several molecular and imaging-based markers have potential for use as biomarkers in these patients and may better define appropriate patient populations.

Differential expression of the angiogenesis growth factors in psoriasis vulgaris

Background

Angiogenesis has been reported to be one of the contributory factors to the pathogenesis of psoriasis vulgaris. This study aims to compare the expression of different angiogenesis growth factors namely (1) the vascular endothelial growth factor (VEGF) subfamily: A, B, C, D and placenta growth factor (PlGF); (2) nerve growth factor (NGF) and (3) von Willebrand factor (vWFr) in the skins of patients with psoriasis vulgaris and non-psoriatic volunteers.

Results

Comparative immunohistochemistry study was performed on the paraffin-sectioned psoriatic and healthy skins with the abovementioned markers. VEGF-C (p = 0.016) and NGF (p = 0.027) were expressed intensely in the cases when compared with the controls. The NGF was the only marker that was solely expressed in the cases and absent in all the controls.

Conclusion

The NGF (angiogenesis) and VEGF-C (lymphangiogenesis) might play a crucial role in the pathogenesis of psoriasis vulgaris and could be researched further as potential new targeted therapies for psoriasis vulgaris.

Molecular mechanisms of retinal pigment epithelium damage and development of age-related macular degeneration

Age-related macular degeneration (AMD) is attributed to a complex interaction of genetic and environmental factors. It is characterized by degeneration involving the retinal photoreceptors, retinal pigment epithelium (RPE) and Bruch's membrane, as well as alterations in choroidal capillaries. AMD pathogenesis is strongly associated with chronic oxidative stress and inflammation that ultimately lead to protein damage, aggregation and degeneration of RPE. Specific degenerative findings for AMD are accumulation of intracellular lysosomal lipofuscin and extracellular drusens. In this review, we discuss thoroughly RPE-derived mechanisms in AMD pathology.

The vascular endothelial growth factor family in adverse pregnancy outcomes

BACKGROUND

Pre-eclampsia, small-for-gestational-age infants, preterm birth and recurrent miscarriage complicate a significant number of pregnancies. The vascular endothelial growth factor (VEGF) family of angiogenic growth factors is implicated in the pathophysiology of these complications. We aimed to elucidate the role of these angiogenic factors in placentation and to evaluate the predictive value of their protein concentrations and genetic variations in pregnancy complications.

METHODS

We performed a systematic search of PubMed, and retrieved original articles. The search included a combination of terms such as VEGF-A, placental growth factor (PlGF), kinase insert domain receptor, fms-like-tyrosine-kinase receptor 1, soluble fms-like-tyrosine-kinase receptor 1, pre-eclampsia, small-for-gestational-age infants, preterm birth, recurrent miscarriage, placenta, prediction and polymorphisms.

RESULTS

This review summarizes the current knowledge of the roles of the VEGF family in early placentation and of the abnormalities in maternal plasma and placental expression of angiogenic proteins in adverse pregnancy outcomes compared with normal pregnancy. PlGF and sFLT-1 in combination with other clinical and biochemical markers in late first or second trimester appear to predict early-onset pre-eclampsia with a high sensitivity and specificity. However, VEGF family proteins do not have sufficient power to accurately predict late-onset pre-eclampsia, small-for-gestational age pregnancies or preterm birth. Functional polymorphisms in these angiogenic genes are implicated in pregnancy complications, but their contribution appears to be minor.

CONCLUSIONS

Although the VEGF family has important roles in normal and complicated pregnancy, the current predictive value of the VEGF family as biomarkers appears to be limited to early-onset pre-eclampsia.

Forty-year journey of angiogenesis translational research

Forty years ago, Judah Folkman predicted that tumor growth is dependent on angiogenesis and that inhibiting this process might be a new strategy for cancer therapy. This hypothesis formed the foundation of a new field of research that represents an excellent example of how a groundbreaking scientific discovery can be translated to yield benefits for patients. Today, antiangiogenic drugs are used to treat human cancers and retinal vascular diseases. Here, we guide readers through 40 years of angiogenesis research and discuss challenges of antiangiogenic therapy.

Cancer therapy modulates VEGF signaling and viability in adult rat cardiac microvascular endothelial cells and cardiomyocytes

This work was motivated by the incomplete characterization of the role of vascular endothelial growth factor-A (VEGF-A) in the stressed heart in consideration of upcoming cancer treatment options challenging the natural VEGF balance in the myocardium. We tested, if the cytotoxic cancer therapy doxorubicin (Doxo) or the anti-angiogenic therapy sunitinib alters viability and VEGF signaling in primary cardiac microvascular endothelial cells (CMEC) and adult rat ventricular myocytes (ARVM). ARVM were isolated and cultured in serum-free medium. CMEC were isolated from the left ventricle and used in the second passage. Viability was measured by LDH-release and by MTT-assay, cellular respiration by high-resolution oxymetry. VEGF-A release was measured using a rat specific VEGF-A ELISA-kit. CMEC were characterized by marker proteins including CD31, von Willebrand factor, smooth muscle actin and desmin. Both Doxo and sunitinib led to a dose-dependent reduction of cell viability. Sunitinib treatment caused a significant reduction of complex I and II-dependent respiration in cardiomyocytes and the loss of mitochondrial membrane potential in CMEC. Endothelial cells up-regulated VEGF-A release after peroxide or Doxo treatment. Doxo induced HIF-1α stabilization and upregulation at clinically relevant concentrations of the cancer therapy. VEGF-A release was abrogated by the inhibition of the Erk1/2 or the MAPKp38 pathway. ARVM did not answer to Doxo-induced stress conditions by the release of VEGF-A as observed in CMEC. VEGF receptor 2 amounts were reduced by Doxo and by sunitinib in a dose-dependent manner in both CMEC and ARVM. In conclusion, these data suggest that cancer therapy with anthracyclines modulates VEGF-A release and its cellular receptors in CMEC and ARVM, and therefore alters paracrine signaling in the myocardium.

Low levels of vascular endothelial growth factor B predict left ventricular remodeling after acute myocardial infarction

BACKGROUND

Left ventricular (LV) remodeling is a prognostically important development after acute myocardial infarction (AMI). We recently reported that vascular endothelial growth factor B (VEGFB) may be a potential new biomarker of LV remodeling. This potential biomarker was evaluated in the present study.

METHODS AND RESULTS

Patients with AMI (n = 290) and healthy volunteers (n = 42) were included. Plasma VEGFB levels were assessed before discharge. LV remodeling was determined by echocardiography at 6 months' follow-up. Levels of VEGFB were elevated in AMI patients compared with healthy volunteers (1.5-fold; P = .001). Mean plasma levels of VEGFB were 64% higher (P < .001) in patients in whom LV end-diastolic volume (EDV) decreased during follow-up (ΔEDV ≤ 0; n = 144; reverse remodeling) compared with patients in whom ΔEDV increased (ΔEDV > 0; n = 146; remodeling). Using logistic regression models, independent relationships were found between VEGFB (odds ratio [OR] 0.8, 95% confidence interval [CI] 0.7-0.9; P = .0007) and infarct territory (OR 1.7, 95% CI 1.1-2.8; P = .02). Patients with anterior MI and low levels of VEGFB had the highest risk of remodeling. VEFGB outperformed N-terminal pro-B-type natriuretic peptide to predict LV remodeling, and low levels of VEGFB (<100 pg/mL) provided a specificity of 90%. Adding VEGFB to a clinical model involving age, sex, smoking habit, and infarct territory resulted in a net reclassification index of 11.7%.

CONCLUSIONS

Plasma levels of VEGFB increase after AMI and correlate with preservation of cardiac function. Low levels of VEGFB accurately predict LV remodeling. Therefore, circulating VEGFB may have clinical utility in the identification of patients at high risk of remodeling after AMI.

Vascular endothelial growth factors in retinal and choroidal neovascular diseases

Angiogenesis, or neovascularization, refers to development of new vessels from pre-existing vasculature. Retinal and choroidal neovascularization leads to oedema, haemorrhages, and fibrosis, causing visual impairment and blindness. In multiple studies, vascular endothelial growth factor (VEGF) has been shown to be the most important factor in ocular angiogenesis. Recently discovered anti-VEGF treatments have revolutionized the therapy of neovascular diseases in the eye. These agents have been shown not just to stop the angiogenic process and maintain visual acuity but also improve vision in a great proportion of patients at least during a 2-year follow-up. However, there are also problems with these agents and their delivery regimens, and new therapeutic strategies are needed. This review summarizes the most important growth factors participating in the angiogenic process in the retina and the choroid, diseases where angiogenesis plays the most devastating part causing visual impairment, as well as current antiangiogenic treatments for these diseases.