No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The Biology of Vascular Endothelial Growth Factor
Abstract
I. Introduction II. Biological Activities of VEGF III. Organization of the VEGF Gene IV. Properties of the VEGF Isoforms V. Regulation of VEGF Gene Expression A. Hypoxia B. Cytokines C. Differentiation and transformation VI. The VEGF Receptors A. Characterization and distribution of VEGF-binding sites B. The Flt-1 and Flk-1/KDR tyrosine kinases 1. Binding characteristics 2. Signal transduction 3. Regulation 4. Structural requirements for ligand binding in Flt-1 and Flk-1/KDR 5. VEGF determinants for binding Flt-1 and Flk-1/KDR VII. VEGF-Related Molecules VIII. Role of VEGF and Its Receptors in Physiological Angiogenesis A. Distribution of VEGF, Flk-1/KDR and Flt-1 mRNA B. Analysis of Flk-1/KDR, Flt-1 and VEGF gene knockouts IX. Role of VEGF in Pathological Angiogenesis A. Tumor angiogenesis 1. Expression of VEGF in human tumors 2. Inhibition of VEGF action in vivo B. Intraocular neovascular syndromes C. Other pathological conditions X. Therapeutic Applications of VEGF-Induced Angiogenesis XI. Perspectives
... Many potential regulators play a role in angiogenesis. VEGF is the most important and most emphasized among angiogenic molecules (FERRARA and DAVIS-SMYTH, 1997;FERRARA, 2000). VEGF is a specific mitogen for vascular endothelial cells, and may contribute to increased angiogenesis and malignancy in CMTs (TAKAHASHI et al., 1995;FERRARA and DAVIS-SMYTH, 1997;RESTUCCI et al., 2002;QUEIROGA et al., 2011). ...
... VEGF is the most important and most emphasized among angiogenic molecules (FERRARA and DAVIS-SMYTH, 1997;FERRARA, 2000). VEGF is a specific mitogen for vascular endothelial cells, and may contribute to increased angiogenesis and malignancy in CMTs (TAKAHASHI et al., 1995;FERRARA and DAVIS-SMYTH, 1997;RESTUCCI et al., 2002;QUEIROGA et al., 2011). ...
... There are many hormones and/or growth factors that regulate angiogenesis. Vascular endothelial growth factor (VEGF) is one of the leading factors involved in angiogenesis (FERRARA et al., 1997). Some studies in CMTs have reported that VEGF protein expression was higher in malignant tumors compared to benign tumors, and gradually increased during canine mammary carcinogenesis (RESTUCCI et al., 2002;QIU et al., 2008). ...
GUNER, E., F. HATIPOGLU: Investigation of the tumor microenvironment, hypoxia and angiogenesis by immunohistochemical and histopathological methods in canine mammary tumors. Vet. arhiv 93, 665-682, 2023. ABSTRACT The tumor microenvironment (TME) is an important component for studying tumor behavior in several cancers in human beings. However, little information regarding the role of the TME in canine mammary tumors (CMTs) is available compared to humans. In this study, the aim was to investigate the relationship between the TME, hypoxia and angiogenesis through CD31, VEGF, HIF-1a, CD68 and CD163 expression by using immunohistochemical (IHC) methods in formalin-fixed paraffin-embedded canine mammary tumor samples [(n=34: malignant (n=28) and benign (n=6)], to compare them with the clinicopathological features of tumors, and to analyze the relationship between them. There was no significant relationship between CD31, VEGF, HIF-1a, CD68 and CD163 expression in malignant tumors compared to benign tumors (P>0.05). There was an association between microvessel density and clinicopathological variables (the tumor size P=0.013, the presence of necrosis P=0.022) and individual histological grade (G2 vs. G3 P=0.028) in malignant tumors. While there was a positive correlation between CD68 and CD163 in malignant tumors in the dogs (P<0.01), no correlation was determined between other antibodies. Immunohistochemical determination of the level of angiogenesis in the TME may give further useful information about the angiogenic potential and grading of the clinical aggressiveness of some CMTs.
... It implies that angiogenesis directly influences endometrial maturation and endometrial receptivity for embryo implantation [9,10] and its importance in determining fertility cannot be overlooked. Among the several known regulators of angiogenesis, vascular endothelial growth factor is one of the major regulators of endothelial cell proliferation, angiogenesis, vasculogenesis and capillary permeability [11][12][13]. Its levels increase around the periimplantation period and act as key regulator of angiogenesis and vascular function in the human endometrium. ...
... Its levels increase around the periimplantation period and act as key regulator of angiogenesis and vascular function in the human endometrium. Alterations in the levels of this factor can cause aberrant endometrial angiogenesis that may result in failure of implantation and recurrent miscarriages [11,14,15]. ...
Aim: Angiogenesis is an essential prerequisite for endometrial development and differentiation. The absence of optimum endometrial perfusion can be one of the important reasons behind patients with unexplained infertility. The present study was undertaken to identify the endometrial vascularity by Doppler and find its relation with serum VEGF in infertile women. Materials And Methods: 60 Patients who qualified for the exclusion and inclusion criteria were enrolled in the study. The patient's blood was obtained by venepuncture on the day of the Doppler examination to be evaluated for serum VEGF. Results: Doppler vascular penetration zones were identified as zone 1, zone 2 and zone 3 i.e. poor, intermediate and good vascularity respectively. A rise in the mean serum VEGF level was observed with the increase in the endometrial vascular penetration zones on Doppler i.e. from 37.67±10.53 pg/ml in Zone 1 to 83.69 ±19.86 pg/ml in Zone 2 to 215.07±25.60pg/ml in Zone3(p<0.05). The Doppler vascular penetration zones were taken as the gold standard, and serum VEGF's cutoff value was determined to predict good endometrial receptivity. Conclusion: Serum VEGF levels were found to rise with increasing Doppler vascular penetration zones, implying that serum VEGF concentrations can be used as a marker of endometrial receptivity.
... The angiogenic and lymphangiogenic characteristics of the vascular endothelial growth factor (VEGF) gene family, which encodes five polypeptides, VEGF-A, -B, -C, -D, and -E, make it particularly significant [199]. The co-receptors neuropilin (NP)-1 and NP-2, as well as the receptor tyrosine kinases VEGF receptor (VEGFR)-1, VEGFR-2, and VEGFR-3, are the primary mechanisms that the VEGF family signals. ...
... VEGF is a cytokine glycoprotein and it is a potent angiotnetic factor that mediate angiogenesis, endothelial wall growth, and vascular permeability. It is produced from capillary endothelial cells, RPE, ganglion cells, Müller cells, and astrocytes [10][11][12][13][14]. Increased levels of serum and VEGF are associated with the pathogenesis of DR [15]. ...
Background
This study aims to investigate the factors affecting the vitreous levels of pigment epithelium-derived factor (PEDF) and vascular endothelial growth factor (VGEF) among patients with pars plana vitrectomy (PPV). Also, this study correlates the levels of PEDF with RRD characteristics.
Methods
All patients who were scheduled for PPV for any indication were included in the study. They were divided into a case group which included patients with advanced PDR and a control group which included the remaining diagnoses. During the PPV, an undiluted vitreous sample was taken and the enzyme-linked immunosorbent assay method was utilized to measure the levels of VEGF and PEDF.
Results
Eighty eyes were involved. Patients diagnosed with advanced PDR and endophthalmitis exhibited higher levels of VEGF. PEDF was affected inversely by the age of the patients and PEDF levels were higher in RRD and endophthalmitis cases. In patients with RRD, the level of PEDF was higher if the tear was found inferiorly, if the macula was detached, and with a longer duration of RRD.
Conclusions
This study highlights the clinical importance of those biomarkers. Anti-VEGF-based treatment is the mainstay against PDR. PEDF may show a promising predictive values regarding patients with RRD.
... Due to the severity and rising prevalence of RVO, effective and widely available treatments are necessary [4]. RVO is characterized by an increase in vascular endothelial growth factor (VEGF), which is a homodimeric protein that stimulates vascular endothelial cell growth and induces vascular permeability [9]. The increase in VEGF is a result of hypoxia caused by the occlusion and its sequelae. ...
This systematic review and meta-analysis aimed to provide an updated evidence base for clinical decision-making by comparing the efficacy and safety of aflibercept 2 mg and ranibizumab in treating retinal vein occlusion (RVO).
A systematic search was conducted using eight databases up to December 2021. Randomized controlled trials (RCTs) and real-world studies (RWSs) comparing aflibercept and ranibizumab in patients with RVO were evaluated. The primary outcomes assessed were efficacy, number of injections administered, and adverse events.
Three RCTs (424 patients) and 11 RWSs (1415 patients) were included. For central RVO (CRVO), RCTs demonstrated a comparable efficacy, whereas RWSs showed that mean changes from baseline in best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were significantly greater with aflibercept compared to ranibizumab; the number of injections of aflibercept was fewer than that of ranibizumab in RCTs, but similar in RWSs. For branch RVO (BRVO), no statistically significant difference in efficacy between the two drugs in RCTs/RWSs was observed, with fewer injections of aflibercept at 12 months in RWSs. The safety profiles of both drugs were similar for both CRVO and BRVO.
For CRVO, aflibercept had similar efficacy and safety profile but with fewer injections versus ranibizumab in RCTs; RWSs showed greater BCVA improvement and CRT reduction with aflibercept than ranibizumab. For BRVO, RCTs showed similar in efficacy, safety, and injection numbers for both drugs, while RWSs demonstrated that aflibercept required fewer injections at 12 months of follow-up. Overall, this study provides updated evidence for clinical decision-making in the treatment of RVO.
... EGF plays a critical role in the activation, migration, and proliferation of endothelial cells in various pathologies [32]. It is especially important during the early phases of proliferation and remodeling, where it acts as a powerful angiogenic stimulator [33]. ...
The human knee is a complex joint that comprises several ligaments, including the medial collateral ligament (MCL). The MCL provides stability to the knee and helps prevent its excessive inward movement. The MCL also has a thin layer of connective tissue known as the epiligament (EL), which adheres to the ligament. This unique feature has drawn attention in the field of ligament healing research, as it may have implications for the recovery process of MCL injuries. According to the EL theory, ligament regeneration relies heavily on the provision of cells, blood vessels, and molecules. The present study sought to compare the expression of vascular endothelial growth factor (VEGF), CD34, and α-smooth muscle actin (α-SMA) in healthy knees’ proximal and distal MCL segments to better understand how these proteins affect ligament healing. By improving the EL theory, the current results could lead to more effective treatments for ligament injury. To conduct the present analysis, monoclonal antibodies were used against CD34, α-SMA, and VEGF to examine samples from 12 fresh knee joints’ midsubstance MCLs. We identified a higher cell density in the EL than in the ligament connective tissue, with higher cell counts in the distal than in the proximal EL part. CD34 immunostaining was weak or absent in blood vessels and the EL, while α-SMA immunostaining was strongest in smooth muscle cells and the EL superficial layer. VEGF expression was mainly in the blood vessels’ tunica media. The distal part showed more SMA-positive microscopy fields and higher cell density than the proximal part (4735 vs. 2680 cells/mm2). Our study identified CD34, α-SMA, and VEGF expression in the MCL EL, highlighting their critical role in ligament healing. Differences in α-SMA expression and cell numbers between the ligament’s proximal and distal parts may explain different healing capacities, supporting the validity of the EL theory in ligament recovery.
... Well-known pro-angiogenic factors include vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), insulin-like growth factor, transforming growth factor (TGF), and angiopoietin (Marech et al., 2016). Among them, the VEGF has been reported as having a crucial role not only in angiogenesis, but also in lymphangiogenesis (Ferrara and Davis-Smyth, 1997). The VEGFs are a family of homodimeric glycoproteins, including VEGF-A, VEGF-B, VEGF-C, VEGF-D and placental growth factor (PlGF) in mammals (Ferrara, 2016). ...
Vascular endothelial growth factors (VEGF), Vascular endothelial growth factor receptors (VEGFR) and their downstream signaling pathways are promising targets in anti-angiogenic therapy. They constitute a crucial system to regulate physiological and pathological angiogenesis. In the last 20 years, many anti-angiogenic drugs have been developed based on VEGF/VEGFR system to treat diverse cancers and retinopathies, and new drugs with improved properties continue to emerge at a fast rate. They consist of different molecular structures and characteristics, which enable them to inhibit the interaction of VEGF/VEGFR, to inhibit the activity of VEGFR tyrosine kinase (TK), or to inhibit VEGFR downstream signaling. In this paper, we reviewed the development of marketed anti-angiogenic drugs involved in the VEGF/VEGFR axis, as well as some important drug candidates in clinical trials. We discuss their mode of action, their clinical benefits, and the current challenges that will need to be addressed by the next-generation of anti-angiogenic drugs. We focus on the molecular structures and characteristics of each drug, including those approved only in China.
... VEGFs play an important role in tumor angiogenesis. They bind to tyrosine kinase receptors on the cell surface, contributing to tumor growth and metastasis [10,11]. Therefore, VEGF signaling pathways are promising targets for cancer therapy; the blockade of VEGF phosphorylation, for instance, leads to changes in vascular characteristics and growth of tumors [12]. ...
Background:
Axitinib, a potent and selective inhibitor of vascular endothelial growth factor (VEGF) receptor (VEGFR) tyrosine kinase 1,2 and 3, is used in chemotherapy because it inhibits tumor angiogenesis by blocking the VEGF/VEGFR pathway. In veterinary medicine, attempts have been made to apply tyrosine kinase inhibitors with anti-angiogenic effects to tumor patients, but there are no studies on axitinib in canine mammary gland tumors (MGTs).
Objectives:
This study aimed to confirm the antitumor activity of axitinib in canine mammary gland cell lines.
Methods:
We treated canine MGT cell lines (CIPp and CIPm) with axitinib and conducted CCK, wound healing, apoptosis, and cell cycle assays. Additionally, we evaluated the expression levels of angiogenesis-associated factors, including VEGFs, PDGF-A, FGF-2, and TGF-β1, using quantitative real-time polymerase chain reaction. Furthermore, we collected canine peripheral blood mononuclear cells (PBMCs), activated them with concanavalin A (ConA) and lipopolysaccharide (LPS), and then treated them with axitinib to investigate changes in viability.
Results:
When axitinib was administered to CIPp and CIPm, cell viability significantly decreased at 24, 48, and 72 h (p < 0.001), and migration was markedly reduced (6 h, p < 0.05; 12 h, p < 0.005). The apoptosis rate significantly increased (p < 0.01), and the G2/M phase ratio showed a significant increase (p < 0.001). Additionally, there was no significant change in the viability of canine PBMCs treated with LPS and ConA.
Conclusion:
In this study, we confirmed the antitumor activity of axitinib against canine MGT cell lines. Accordingly, we suggest that axitinib can be applied as a new treatment for patients with canine MGTs.
... Beside EGFR, there is another receptor tyrosine kinase named vascular endothelial growth factor-2 (VEGFR-2) which has been implicated in NSCLC. VEGFR-2 is known to regulate vasculogenesis, angiogenesis, hematopoiesis, lymphangiogenesis, and vascular permeability [11,12]. Blocking of VEGFR-2 has been shown to inhibit angiogenesis which can prove effective against cancer. ...
Lung malignancy is a major worldwide issue that occurs due to the dysregulation of various growth factors. Lung cancer has no apparent signs in the early stages, which makes it harder to catch it in time and leads to a higher fatality rate. So, the goal of this work was to create and analyze a novel chemical molecule called 4-nitro acetophenone thiosemicarbazone (4-NAPTSc) against the lung cancer cell line A549 and human non-tumorigenic lung epithelial cell line BAES-2B. The ligand was synthesized by refluxing the reaction mixture of 4-nitro acetophenone and thiosemicarbazide and was further characterized by UV, FTIR, and ¹H and ¹³C NMR and Differential Scanning Calorimetry (DSC) study. Cytotoxicity assay/MTT (3-(4,5-dimethylthiazol-2-yl))2,5-diphenyltetrazolium bromide) was used to evaluate the cytotoxicity of the compound. Epidermal growth factor receptors (EGFR), polo-like kinase-1 (PLK1), and vascular endothelial growth factor receptors (VEGFR) were chosen as the target proteins for molecular docking to find potential ligand binding sites and inhibit their function. A novel yellow-colored crystalline solid has been synthesized. 4-NAPTSc had an IC50 of 2.93 μg/mL against the A549 lung cancer cells. When the dosage is increased from 5 to 15 μg/mL along with time, the cell viability falls. Docking results showed that the compound binds with the targeted proteins’ amino acid residues, and the likeness profile of the compound is also favorable. This study reveals that the compound has the potential for further investigation and can be used in multitargeted cancer therapies.
Graphical Abstract
... Platelets are known to be major contributors of circulating VEGF (211). VEGF binds to two tyrosine kinase receptors (VEGFRs), VEGFR-1 and VEGFR-2 (212). ...
Over the last decade, a considerable amount of new data have revealed the beneficial effects of exercise on hippocampal neurogenesis and the maintenance or improvement of cognitive function. Investigations with animal models, as well as human studies, have yielded novel understanding of the mechanisms through which endocrine signaling can stimulate neurogenesis, as well as the effects of exercise on acute and/or chronic levels of these circulating hormones. Considering the effects of aging on the decline of specific endocrine factors that affect brain health, insights in this area of research are particularly important. In this review, we discuss how different forms of exercise influence the peripheral production of specific endocrine factors, with particular emphasis on brain-derived neurotrophic factor, growth hormone, insulin-like growth factor-1, ghrelin, estrogen, testosterone, irisin, vascular endothelial growth factor, erythropoietin, and cortisol. We also describe mechanisms through which these endocrine responses to exercise induce cellular changes that increase hippocampal neurogenesis and improve cognitive function.
... To evaluate whether vascular alterations detected in H&E sections of the present study resulted from variation in ASDJ Ain Shams Dental Journal VEGF expression, its immune-expression was examined in the different groups. VEGF is established as a key regulator of physiological angiogenesis during development and also in pathology [60] . ...
... The family of vascular endothelial growth factor (VEGF) and related receptors (VEGFRs) play a critical role in the regulation of pathological angiogenesis [8,9]. VEGF has been shown to strongly induce proliferation, cell migration, and tube formation with a chracteristic specificity for endothelial cells [10]. Therefore, angiogenesis inhibition via VEGF-mediated crucial signaling has been considered a promising strategy for the treatment of angiogenesis-related diseases. ...
Low molecular weight collagen peptide (LMWCP) is a collagen hydrolysate derived from fish. We investigated the effects of LMWCP on hair growth using human dermal papilla cells (hDPCs), human hair follicles (hHFs), patch assay, and telogenic C57BL/6 mice, while also examining the underlying mechanisms of its action. LMWCP promoted proliferation and mitochondrial potential, and the secretion of hair growth-related factors, such as EGF, HB-EGF, FGF-4, and FGF-6 in hDPCs. Patch assay showed that LMWCP increased the neogeneration of new HFs in a dose-dependent manner. This result correlated with an increase in the expression of dermal papilla (DP) signature genes such as, ALPL, SHH, FGF7, and BMP-2. LMWCP upregulated phosphorylation of glycogen synthase kinase-3β (GSK-3β) and β-catenin, and nuclear translocation of β‑catenin, and it increased the expression of Wnt3a, LEF1, VEGF, ALP, and β-catenin. LMWCP promoted the growth of hHFs and increased the expression of β-catenin and VEGF. Oral administration of LMWCP to mice significantly stimulated hair growth. The expression of Wnt3a, β-catenin, PCNA, Cyclin D1, and VEGF was also elevated in the back skin of the mice. Furthermore, LMWCP increased the expression of cytokeratin and Keratin Type Ⅰ and Ⅱ. Collectively, these findings demonstrate that LMWCP has the potential to increase hair growth via activating the Wnt/β-catenin signaling pathway.
... VEGF-A, VEGF-B, VEGF-C, VEGF-D, and placental growth factor. 31 VEGF-C and VEGF-D are known for their ability to induce lymphangiogenesis but are also mitogenic for vascular endothelial cells during embryonic development. 18 VEGF-D acts as a competitive agonist for VEGF-C, and the downregulation of VEGF-D has been shown to result in the greater upregulation of VEGF-C, a more potent angiogenic cytokine than VEGF-D. ...
Objective
This study aimed to investigate maternal serum vascular endothelial growth factor (VEGF) C and D levels in patients with intrahepatic cholestasis of pregnancy (ICP).
Methods
A total of 83 patients, including 41 patients with ICP and 42 healthy pregnant women, were included in the study. We first compared the maternal serum VEGF‐C and VEGF‐D levels between the ICP and control groups and then examined the correlation between the serum VEGF‐C level and the bile acid level in patients with severe ICP.
Results
We observed statistically significantly higher serum VEGF‐C levels and lower VEGF‐D levels in the ICP group compared with the healthy controls (P < 0.001 and P = 0.015, respectively). According to receiver operating characteristic analysis, the optimal cutoff value for ICP was 147 ng/mL in the determination of the VEGF‐C level (specificity and sensitivity: 76%). In patients with severe ICP, the serum VEGF‐C statistically significantly correlated with the bile acid level (P = 0.019).
Conclusion
This study showed that the maternal serum VEGF‐C level was higher and the VEGF‐D level was lower in patients with ICP compared with healthy pregnant women. We also found that the VEGF‐C level was correlated with the serum bile acid level in patients with severe ICP. Serum VEGF‐C level can be used in the diagnosis and follow‐up of intrahepatic pregnancy cholestasis.
... VEGF is an established stimulator of physiological and pathophysiological angiogenesis [11,12], whilst it also acts as a pro-inflammatory cytokine by increasing the permeability of the endothelial barrier and by being chemotactic for monocytes [13,14]. The expression and activation of HIF-1α as a transcription factor is regulated by hypoxia and glucose [15,16]. ...
Type 1 diabetes (T1D) is associated with hyperglycaemia-induced hypoxia and inflammation. This study assessed the effects of a single bout of high-intensity interval exercise (HIIE) on glycaemia (BG) and serum level of pro-inflammatory cytokines, and an essential mediator of adaptive response to hypoxia in T1D patients. The macronutrient intake was also evaluated. Nine patients suffering from T1D for about 12 years and nine healthy individuals (CG) were enrolled and completed one session of HIIE at the intensity of 120% lactate threshold with a duration of 4 × 5 min intermittent with 5 min rests after each bout of exercise. Capillary and venous blood were withdrawn at rest, immediately after and at 24 h post-HIIE for analysis of BG, hypoxia-inducible factor alpha (HIF-1α), tumour necrosis factor alpha (TNF-α) and vascular-endothelial growth factor (VEGF). Pre-exercise BG was significantly higher in the T1D patients compared to the CG (p = 0.043). HIIE led to a significant decline in T1D patients’ BG (p = 0.027) and a tendency for a lower BG at 24 h post-HIIE vs. pre-HIIE. HIF-1α was significantly elevated in the T1D patients compared to CG and there was a trend for HIF-1α to decline, and for VEGF and TNF-α to increase in response to HIIE in the T1D group. Both groups consumed more and less than the recommended amounts of protein and fat, respectively. In the T1D group, a tendency for a higher digestible carbohydrate intake and more frequent hyperglycaemic episodes on the day after HIIE were observed. HIIE was effective in reducing T1D patients’ glycaemia and improving short-term glycaemic control. HIIE has the potential to improve adaptive response to hypoxia by elevating the serum level of VEGF. Patients’ diet and level of physical activity should be screened on a regular basis, and they should be educated on the glycaemic effects of digestible carbohydrates.
... The most frequently expressed variants are VEGF121, 165, and 189, of which VEGF165 is the most frequently expressed and has the strongest angiogenic effect (39). VEGF-A binds to vascular endothelial growth factor receptor 1 (VEGFR-1) and VEGFR-2, and its affinity for VEGFR-1 is 10-fold stronger than that for VEGFR-2 (40). ...
Colorectal cancer is the third most common disease and the second most common cause of death in the world. The drug for second-line treatment depends on the drugs used in first-line treatment and biomarker status. As biomarkers, the RAS gene, BRAF gene, and dMMR/MSI-H, TMB-H, and HER2 statuses have been established in clinical practice, and the corresponding molecularly targeted therapeutic agents are selected based on biomarker status. Given the frequency of biomarkers, it is assumed that when patients move on to second-line treatment, an angiogenesis inhibitor is selected in many cases. For second-line treatment, three angiogenesis inhibitors, bevacizumab (BEV), ramucirumab (RAM), and aflibercept (AFL), are available, and one of them is combined with cytotoxic agents. These three angiogenesis inhibitors are known to inhibit angiogenesis through different mechanisms of action. Although no useful biomarkers are established for selecting angiogenesis inhibitors, previous biomarker studies have suggested that angiogenesis-related factors such as VEGF-A and VEGF-D might be predictors of therapeutic efficacy of angiogenesis inhibitors. These biomarkers are measured as protein levels in plasma and are considered to be hopeful biomarkers. We consider that the rationale for selecting among these three angiogenesis inhibitors should be clarified to benefit patients.
... VEGF is an established stimulator of physiological and pathophysiological angiogenesis [11,12], whilst it also acts as a pro-inflammatory cytokine via increasing permeability of the endothelial barrier and by being chemotactic for monocytes [13,14]. The expression and activation of HIF-1α as a transcription factor, is regulated by hypoxia and glucose [15,16]. ...
Type 1 diabetes (T1D) is associated with hyperglycaemia-induced hypoxia and inflammation. The study assessed the effects of a single high-intensity interval exercise (HIIE) on glycaemia (BG) and serum level of pro-inflammatory cytokines and an essential mediator of adaptive response to hypoxia in T1D patients. The macronutrients intake was also evaluated. Nine patients suffering from T1D for about 12 years and nine healthy individuals (CG) were enrolled and completed one session of HIIE at the intensity of 120% lactate threshold and duration of 4 x 5 min intermittent with 5 min rest after each bout of exercise. Capillary and venous blood was withdrawn at rest, immediately after and at the 24 h post-HIIE for analysis of BG, hypoxia-inducible factor alpha (HIF-1α), tumour necrosis factor alpha (TNF-α) and vascular-endothelial growth factor (VEGF). Pre-exercise BG was significantly higher in the T1D compared to the CG (p = 0.043). HIIE led to a significant decline in T1D patients’ BG (p = 0.027) and to a tendency for a lower BG at 24-h post-HIIE vs pre-HIIE. HIF-1α was significantly elevated in the T1D compared to CG and there was a trend for HIF-1α to decline, and VEGF, TNF-α to increase in response to HIIE in the T1D group. Both groups consumed higher and lower than recommended amounts of protein and fat, respectively. In T1D group, a tendency for a higher digestible carbohydrate intake and more frequent hyperglycaemic episodes on the day after HIIE were observed. HIIE was effective in reducing T1D patients’ glycaemia and improving the short-term glycaemic control. HIIE has the potential to improve adaptive response to hypoxia by elevating the serum level of VEGF. Patients’ diet and level of physical activity should be screened on a regular basis, and they should be educated on the glycaemic effects of digestible carbohydrates.
... VEGFA is the most dominant and is often referred to as VEGF [9]. Alternative splicing of mRNA results in the formation of multiple VEGFA isoforms with varying amino acid numbers in the final structure, such as VEGF 121 , VEGF 165 and VEGF 189 [10]. VEGF 165 is the most widely studied isoform. ...
VEGF165 and its isoform VEGF165b have the same length but opposite functions in cancer. Some studies have indicated the important role of VEGF165 in osteosarcoma (OS); however, VEGF165b has not been taken into consideration. This study aims to clarify the roles of the two isoforms in OS and the mechanism controlling their formation from an alternative splicing perspective. By in vivo and in vitro experiments, we assessed the expression and function of VEGF165 and VEGF165b, screened the underlying splicing factors, and verified the regulatory function of splicing factor YBX1 on the two isoforms and its role in OS. The results showed that in OS, VEGF165 was upregulated but VEGF165b was downregulated. VEGF165 promoted the proliferation, migration and invasion of OS cells and induced angiogenesis in OS tumours; however, VEGF165b showed the opposite function. Of the four screened splicing factors, YBX1 was upregulated in OS tissues. It was positively correlated with VEGF165 but negatively correlated with VEGF165b. Further study indicated that YBX1 could upregulate VEGF165 but downregulate VEGF165b. Moreover, YBX1 promoted the proliferation, migration and invasion of OS cells and induced angiogenesis in OS tumours. OS patients with higher YBX1 had a poor prognosis within five years, but this difference disappeared in a longer follow-up. In conclusion, VEGF165b was antineoplastic and downregulated in OS, in contrast to VEGF165. YBX1 was found to be an important splicing factor that increased VEGF165 but decreased VEGF165b. Targeting YBX1 could endogenously alter the levels of VEGF165 and VEGF165b simultaneously.
... The disordered expression of angiogenic factors and their receptors is also associated with BPD-impaired function of pulmonary microvascular. Vascular endothelial growth factor-A (VEGFA) is one of several angiogenic factors that play a central role in the development and function of arteries and veins 8,9 . Furthermore, the disruption of VEGFA signaling contributes to the pathogenesis of BPD by impairing lung vascular growth. ...
Bronchopulmonary dysplasia (BPD) is characterized by abnormal development of the blood vessels and alveoli in lungs, which largely occurs in premature infants. Exosomes (EXO) from very preterm infants (VPI) with BPD (BPD-EXO) impair angiogenic activities of human umbilical vein endothelial cells (HUVECs) via EXO-miRNAs cargo. This study aimed to determine whether and how BPD-EXO affect the development of BPD in a mouse model. We showed that treating BPD mice with BPD-EXO chronically and irreversibly aggravated lung injury. BPD-EXO up-regulated 139 and down-regulated 735 genes in the mouse lung tissue. These differentially expressed genes were enriched to the MAPK pathway (e.g., Fgf9 and Cacna2d3), which is critical to angiogenesis and vascular remodeling. BPD-EXO suppressed expression of Fgf9 and Cacna2d3 in HUVECs and inhibited migration, tube formation, and increased cell apoptosis in HUVECs. These data demonstrate that BPD-EXO aggravate lung injury in BPD mice and impair lung angiogenesis, plausibly leading to adverse outcomes of VPI with BPD. These data also suggest that BPD-EXO could serve as promising targets for predicting and treating BPD.
... Abnormal vessel structure and function result in a favorable environment, such as hypoxia and acidosis, for tumor growth and metastasis. The abnormal increase of tumor blood vessels is mostly attributed to the vascular endothelial growth factor (VEGF) family proteins, which can active diverse signaling networks, including vascular permeability, vascular system differentiation and pathogenesis of various disorders 4 . It has been widely acknowledged that tumor metastasis and/or tumor vascularity tightly correlate with VEGF expression levels [5][6][7] . ...
Background
As one member of lipid raft proteins, STOML2 is up-regulated in several tumor types and participates in the tumor progression. We investigated the biological function and the underlying mechanism of STOML2 in colorectal cancer (CRC).
Methods
We used Real-time PCR and immunohistochemical analysis to access the levels of STOML2 in 7 CRC cell lines and 119 human paraffin-embedded CRC samples. Immunohistochemical analysis was performed to measure the expression of Ki67, CD31 and VEGFC in 50 human CRC samples. We determined the ability of STOML2 to activate NF-κB signaling using luciferase reporter assay, Real-time PCR and western blotting. The effects of STOML2 overexpression and knockdown with its specific short hairpin RNAs in CRC cell lines were detected using colony formation and tube formation assays. We analyzed development of CRC xenograft tumors in nude mice.
Results
STOML2 expression levels were increased in CRC cell lines and samples from CRC patients, compared with normal controls, and were associated with disease stage and survival outcomes. Overexpression of STOML2 in HCT116 and SW480 cell lines promoted proliferation and angiogenesis via promoting lipid raft formation and activating the NF-κB pathway. STOML2-induced angiogenesis effects could be greatly reversed by bevacizumab, a therapeutic monoclonal antibody against target with VEGF. Moreover, STOML2-overexpressing CRC cells formed larger tumors featured with more neovascularization in nude mice as compared to vector-control CRC cells. We identified STOML2 as independent prognostic factor in CRC.
Conclusions
The lipid raft protein STOML2 is up-regulated in CRC cell lines and tissues from patients and promotes CRC cell proliferation and angiogenesis in vitro and in vivo. STOML2 promotes lipid raft formation and activates the NF-κB signaling pathway in CRC cells. Our findings suggest that STOML2 functions as an oncoprotein and a prognostic factor in CRC, which might use to identify whether CRC patients may benefit from bevacizumab therapy.
... VEGF1 promotes both SC migration and axon development [181,182]. Vascular permeability angiogenesis is increased by VEGF [183][184][185]. Three different phosphotyrosine kinase receptors called VEGFR-1 (also known as fms-like tyrosine kinase 1 or flt1), VEGFR-2 (also known as kinase insert-domain containing receptor, foetal liver kinase 1, flk1 in mice or KDR in humans), and VEGFR-3 are thought to be involved in the putative action of VEGF [186]. ...
Recently, much attention has been paid to chronic neuro-inflammatory condition underlying neuropathic pain. It is generally linked with thermal hyperalgesia and tactile allodynia. It results due to injury or infection in the nervous system. The neuropathic pain spectrum covers a variety of pathophysiological states, mostly involved are ischemic injury viral infections associated neuropathies, chemotherapy-induced peripheral neuropathies, autoimmune disorders, traumatic origin, hereditary neuropathies, inflammatory disorders, and channelopathies. In CNS, angiogenesis is evident in inflammation of neurons and pain in bone cancer. The role of chemokines and cytokines is dualistic; their aggressive secretion produces detrimental effects, leading to neuropathic pain. However, whether the angiogenesis contributes and exists in neuropathic pain remains doubtful. In the present review, we elucidated summary of diverse mechanisms of neuropathic pain associated with angiogenesis. Moreover, an overview of multiple targets that have provided insights on the VEGF signaling, signaling through Tie-1 and Tie-2 receptor, erythropoietin pathway promoting axonal growth are also discussed. Because angio-genesis as a result of these signaling, results in inflammation, we focused on the mechanisms of neuropathic pain. These factors are mainly responsible for the activation of post-traumatic regeneration of the PNS and CNS. Furthermore, we also reviewed synthetic and herbal treatments targeting angiogenesis in neuropathic pain.
Placental insufficiency is one of the major causes of fetal growth restriction (FGR), a significant pregnancy disorder in which the fetus fails to achieve its full growth potential in utero. As well as the acute consequences of being born too small, affected offspring are at increased risk of cardiovascular disease, diabetes and other chronic diseases in later life. The placenta and heart develop concurrently, therefore placental maldevelopment and function in FGR may have profound effect on the growth and differentiation of many organ systems, including the heart. Hence, understanding the key molecular players that are synergistically linked in the development of the placenta and heart is critical. This review highlights the key growth factors, angiogenic molecules and transcription factors that are common causes of defective placental and cardiovascular development.
Paraspeckles are ribonucleoproteins found in the interchromatin space of the mammalian cell nucleus that has been recently enlightened. Paraspeckles proteins are mammalian DBHS protein family proteins consisting of non-POU domain containing octamer binding (NONO/p54nrb), paraspeckle protein 1 (PSPC1) and splicing factor proline and glutamine rich (PSF/SFPQ) proteins. In addition, there is an uncoded RNA, NEAT1, in the paraspeckle structure. NONO/p54 nrb is involved in a variety of biological processes.With this thesis study, the relationship of NONO / p54nrb gene with angiogenesis has been elucidated The association of NONO / p54 nrb gene and other paraspeckle members with VEGF cytokine and hypoxia, which are the most important regulators of angiogenesis, was confirmed by Real Time PCR and westernblot experiments. In both normal and hypoxic conditions, an increase in m RNA and protein levels was observed in experimental groups. These data are supported with VEGF pathway inhibition assays.Luciferase reporter experiments confirmed that the NONO / p54nrb promoter is also associated with the VEGF pathway and hypoxia. The fact that the NONO / p54 nrb gene is important and necessary for paraspecle genes has been confirmed by overexpression and knockdown experiments. It was confirmed that NONO / p54nrb gene plays a role in cellular processes experiments performed after overexpression and knockdown experiments. All these studies have shown that the NONO / p54nrb gene has an important role in angiogenesis and plays a role in the cancer process.
Formation of organo-typical vascular networks requires cross-talk between differentiating parenchymal cells and developing blood vessels. Here we identify a Vegfa driven venous sprouting process involving parenchymal to vein cross-talk regulating venous endothelial Vegfa signaling strength and subsequent formation of a specialized angiogenic cell, prefabricated with an intact lumen and pericyte coverage, termed L-Tip cell. L-Tip cell selection in the venous domain requires genetic interaction between vascular Aplnra and Kdrl in a subset of venous endothelial cells and exposure to parenchymal derived Vegfa and Apelin. Parenchymal Esm1 controls the spatial positioning of venous sprouting by fine-tuning local Vegfa availability. These findings may provide a conceptual framework for understanding how Vegfa generates organo-typical vascular networks based on the selection of competent endothelial cells, induced via spatio-temporal control of endothelial Kdrl signaling strength involving multiple parenchymal derived cues generated in a tissue dependent metabolic context.
Purpose
To assess intra‐ (repeatability) and inter‐observer (reproducibility) variability of laser speckle flowgraphy (LSFG) for retinal blood flow (RBF) measurement in 20 eyes of wild type (C57BL/6J) mice and effect of intravitreal Aflibercept on RBF in optic nerve head (ONH) region of 10 eyes of Ins2 (Akita) diabetic mice.
Methods
‘Mean blur rate (MBR)’ was measured for all quadrants of tissue area (MT), vessel (MV) and total area (MA) of ONH region. Changes in MT were analysed at each timepoint. Repeatability was evaluated by measuring MBR variability without changing mouse head position, and reproducibility after resetting mouse head position by another operator. Coefficient of repeatability (CR) through Bland–Altman plot method coefficient of variation (COV) and Intraclass correlation coefficient (ICC) was calculated. Intravitreal Aflibercept (1 μg) was administered to Akita eyes and intraocular pressure (IOP) was measured using a tonometer at baseline, day 7, 14, 21 and 28 post‐injection. Hurvich and Tsai's criterion was used.
Results
Coefficient of repeatability values of repeatability and reproducibility for all quadrants were within limits of agreement. Reliability was excellent (ICC 0.98–0.99) and reproducibility was moderate to excellent (ICC 0.64–0.96). There was a non‐significant IOP increase in all Akita eyes at Day 28 ( p > 0.05), and significant increase in MT in all quadrants at Day 21 and superior, inferior and temporal quadrants at Day 28 ( p < 0.05).
Conclusion
Laser speckle flowgraphy demonstrates excellent repeatability and moderate to excellent reproducibility in measuring RBF. Intravitreal Aflibercept injection results in a significant increase in MT up to 28 days post‐injection without significant increase in IOP.
Simple Summary
This manuscript discusses the ongoing challenge of cancer as a leading global cause of death despite advancements in therapies. It highlights the role of hyperthermia (HT) as a modality in cancer treatment, particularly its effectiveness as a sensitizer and its impact on cancer–immunity processes and oncogenic pathways. The article notes the recent focus on immunotherapy (IT) and targeted therapy (TT) in cancer research, both in academia and pharmaceutical companies. The main focus of the manuscript is to explore potential therapies that can enhance the effects of HT by targeting molecular pathways. The ultimate goal is to pave the way for future research and clinical trials, aiming to harness the synergistic potential of combining emerging IT and TT with HT for improved outcomes.
Abstract
Despite significant advancements in the development of novel therapies, cancer continues to stand as a prominent global cause of death. In many cases, the cornerstone of standard-of-care therapy consists of chemotherapy (CT), radiotherapy (RT), or a combination of both. Notably, hyperthermia (HT), which has been in clinical use in the last four decades, has proven to enhance the effectiveness of CT and RT, owing to its recognized potency as a sensitizer. Furthermore, HT exerts effects on all steps of the cancer–immunity cycle and exerts a significant impact on key oncogenic pathways. Most recently, there has been a noticeable expansion of cancer research related to treatment options involving immunotherapy (IT) and targeted therapy (TT), a trend also visible in the research and development pipelines of pharmaceutical companies. However, the potential results arising from the combination of these innovative therapeutic approaches with HT remain largely unexplored. Therefore, this review aims to explore the oncology pipelines of major pharmaceutical companies, with the primary objective of identifying the principal targets of forthcoming therapies that have the potential to be advantageous for patients by specifically targeting molecular pathways involved in HT. The ultimate goal of this review is to pave the way for future research initiatives and clinical trials that harness the synergy between emerging IT and TT medications when used in conjunction with HT.
Rationale
Most Chinese patients with locally advanced gastric cancer at diagnosis have an overall 5-year survival rate of <50%. Surgical resection alone is not suitable for patients with locally advanced gastric cancer. Currently, comprehensive treatment is the focus of locally advanced gastric cancer.
Patients concerns
The patient, a 56-year-old female, was admitted to the hospital because of “4 + months of double hydronephrosis found during a physical examination.” Who was admitted for computer tomography and gastroscopy examinations, and take pathological tissue specimens during endoscopic examination.
Diagnoses
Computed tomography assessment indicated ulcerative gastric cancer with an abdominal implant, bladder, and bone metastases. An endoscopic examination revealed that the ulcer of the gastric angle was huge, and through relevant auxiliary examinations, the diagnosis of this disease is gastric cancer complicated with multiple metastases to bladder, rectum, lumbar spine, and peritoneum. Clinically diagnosed as cT4bN3M1.
Interventions
The patient is currently undergoing first, second, and third line neoadjuvant therapy, combined with immunotherapy, targeted therapy, neoadjuvant intraperitoneal systemic chemotherapy, nutritional support, and other treatment plans.
Outcomes
After 15 cycles of treatment, the progression-free survival had reached 15 months. The patient had an NRS2002 score of 1, an ECOG score of I, a quality of life score of 55, albumin of 35.27 g/L, and a decrease in abdominal and pelvic fluid accumulation and exudation compared to before.
Lessons
We demonstrated high survival of almost 3 years in a patient with gastric cancer that was complicated by bone, peritoneal, rectal, and bladder metastases. The combination of immunotherapy, targeted therapy, and neoadjuvant intraperitoneal systemic chemotherapy, along with the maintenance of nutritional status and CTCs could be a valuable modality for the subsequent treatment and observation of similar patients.
The skin’s recognised functions may undergo physiological alterations due to ageing, manifesting as varying degrees of facial wrinkles, diminished tautness, density, and volume. Additionally, these functions can be disrupted (patho)physiologically through various physical and chemical injuries, including surgical trauma, accidents, or chronic conditions like ulcers associated with diabetes mellitus, venous insufficiency, or obesity. Advancements in therapeutic interventions that boost the skin’s innate regenerative abilities could significantly enhance patient care protocols. The application of Platelet-Rich Plasma (PRP) is widely recognized for its aesthetic and functional benefits to the skin. Yet, the endorsement of PRP’s advantages often borders on the dogmatic, with its efficacy commonly ascribed solely to the activation of fibroblasts by the factors contained within platelet granules. PRP therapy is a cornerstone of regenerative medicine which involves the autologous delivery of conditioned plasma enriched by platelets. This is achieved by centrifugation, removing erythrocytes while retaining platelets and their granules. Despite its widespread use, the precise sequences of cellular activation, the specific cellular players, and the molecular machinery that drive PRP-facilitated healing are still enigmatic. There is still a paucity of definitive and robust studies elucidating these mechanisms. In recent years, telocytes (TCs)—a unique dermal cell population—have shown promising potential for tissue regeneration in various organs, including the dermis. TCs’ participation in neo-angiogenesis, akin to that attributed to PRP, and their role in tissue remodelling and repair processes within the interstitia of several organs (including the dermis), offer intriguing insights. Their potential to contribute to, or possibly orchestrate, the skin regeneration process following PRP treatment has elicited considerable interest. Therefore, pursuing a comprehensive understanding of the cellular and molecular mechanisms at work, particularly those involving TCs, their temporal involvement in structural recovery following injury, and the interconnected biological events in skin wound healing and regeneration represents a compelling field of study.
Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogen-activated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.
The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone‐regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue‐engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.
Para estudiar si el efecto del factor de crecimiento vascular endotelial (VEGF) está alterado en las arterias tumorales, se obtuvieron arterias mesentéricas irrigando el tumor y arterias mesentéricas de una región alejada del mismo (controles) de 4 pacientes intervenidos quirúrgicamente por cáncer colorrectal, y se montaron en una preparación para el registro de la contracción isométrica en un baño de órganos. La depolarización del músculo liso vascular mediante una concentración elevada de potasio (100 mM) produjo contracción que fue menor en las arterias del tumor que en las controles. En las arterias contraídas previamente con el análogo del tromoboxano U46618, el VEGF (10-8-10-9 M) produjo relajación que fue similar en las arterias del tumor que en las controles. Estos resultados indican que en las arterias de tumores colorrectales la capacidad vasoconstrictora del músculo liso está reducida pero el efecto vasodilatador del VEGF está preservado, lo que puede contribuir a mantener el flujo sanguíneo al tumor durante su crecimiento.
Background: The global epidemic status of diabetic retinopathy (DR) and its burden presents an ongoing challenge to health-care systems. It is of great interest to investigate potential prognostic biomarkers of DR. Such markers could aid in detecting early stages of DR, predicting DR progression and its response to therapeutics. Herein, we investigate the prognostic value of intravitreal concentrations of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) in a DR cohort. Materials and methods: Vitreous sample acquisition was conducted at King Abdullah University Hospital (KAUH) between December 2020 and June 2022. Samples were obtained from any patient scheduled to undergo a pars plana vitrectomy (PPV) for any indication. Included patients were categorized into a DR group or a corresponding non-diabetic (ND) control group. Demographics, clinicopathological variables, standardized laboratory tests results, and optical coherence tomography (OCT) data were obtained for each included individual. Intravitreal concentrations of VEGF and PDGF were assessed using commercial enzyme-linked immunosorbent assay (ELISA). Results: A total of 80 eyes from 80 patients (DR group: n = 42 and ND control group: n = 38) were included in the analysis. The vitreous VEGF levels were significantly higher in the DR group compared to the ND control group (DR group 5744.06 ± 761.5 pg/mL versus ND control group 817.94 ± 403.1 pg/mL, p = 0.0001). In addition, the vitreous PDGF levels were also significantly higher in the DR group than those in the ND control group (DR group 4031.51 ± 410.2 pg/mL versus ND control group 2691.46 ± 821.0 pg/mL, p = 0.001). Bassline differences between test groups and clinical factors impacting VEGF and PDGF concentrations were investigated as well. Multiple regression analysis indicated PDGF as the sole independent risk factor affecting best-corrected visual acuity (BCVA) at the last follow-up visit: the higher the PDGF vitreous levels, the worst the BCVA. Conclusions: Vitreous concentrations of VEGF and PDGF are correlated with DR severity and may exhibit a possible prognostic potential value in DR. Further clinical and experimental data are warranted to confirm the observed findings and to help incorporate them into daily practice.
Graphene oxide (GO) and reduced graphene oxide (rGO) have been widely used in the field of tissue regeneration and various biomedical applications. In order to use these nanomaterials in organisms, it is imperative to possess an understanding of their impact on different cell types. Due to the potential of these nanomaterials to enter the bloodstream, interact with the endothelium and accumulate within diverse tissues, it is highly relevant to probe them when in contact with the cellular components of the vascular system. Endothelial progenitor cells (EPCs), involved in blood vessel formation, have great potential for tissue engineering and offer great advantages to study the possible angiogenic effects of biomaterials. Vascular endothelial growth factor (VEGF) induces angiogenesis and regulates vascular permeability, mainly activating VEGFR2 on endothelial cells. The effects of GO and two types of reduced GO, obtained after vacuum-assisted thermal treatment for 15 min (rGO15) and 30 min (rGO30), on porcine endothelial progenitor cells (EPCs) functionality were assessed by analyzing the nanomaterial intracellular uptake, reactive oxygen species (ROS) production and VEGFR2 expression by EPCs. The results evidence that short annealing (15 and 30 minutes) at 200 °C of GO resulted in the mitigation of both the increased ROS production and decline in VEGFR2 expression of EPCs upon GO exposure. Interestingly, after 72 hours of exposure to rGO30, VEGFR2 was higher than in the control culture, suggesting an early angiogenic potential of rGO30. The present work reveals that discrete variations in the reduction of GO may significantly affect the response of porcine endothelial progenitor cells.
We present a case of biliary bleeding caused by gallbladder perforation caused by a tumor that occurred immediately after combination therapy with atezolizumab and bevacizumab for advanced hepatocellular carcinoma. The male patient in his 70s with advanced hepatocellular carcinoma was treated with combination therapy of atezolizumab and bevacizumab on day 1 and experienced epigastralgia on day 2. On day 3, we determined that biliary obstruction had occurred due to biliary bleeding caused by gallbladder perforation caused by the tumor, and we performed biliary drainage via emergency endoscopic retrograde cholangiopancreatography. To treat tumor bleeding from the tumor, we used hepatic artery embolization of tumor blood vessel A6 on day 6. Bevacizumab was thought to have caused the biliary hemorrhage, so the combination therapy of atezolizumab and bevacizumab was stopped, lenvatinib was introduced, and subsequent CT revealed tumor shrinkage.
Comprehensive systematic account of the development of the avian respiratory system, specifically that of the domestic fowl, Gallus gallus variant domesticus, is presented. Factors and conditions that determine and drive the intricate morphogenetic processes are presented and the most important morphological changes are specified. Ensuing developmental processes such as branching morphogenesis and the role that molecular factors (morphogenetic cues) play in elaboration of the complex morphology of the avian respiratory system is specified. Very early in its development, the lung is firmly affixed to the vertebrae and the ribs on the dorsolateral aspects and the air sacs form as blister-like outgrowths from the cranial, the ventral, and the caudal edges of the organ. At the end of the incubation period, i.e., at hatching (day 21), for the precocial domestic fowl, the respiratory system is well-developed for gas exchange: the air- and the blood capillaries are well-formed, the blood-gas barrier is very thin, and the respiratory surface area is large.
We aimed to evaluate the impact of corpus luteum (CL) and uterine characteristics accessed by B-mode and Color-Doppler ultrasonography in recipient mares at the time of embryo transfer (ET) on pregnancy outcomes. Recipient mares (n = 110), between days 3-9 after spontaneous ovulation, received a fresh embryo. Immediately before ET, the reproductive system was assessed by transrectal palpation for the following parameters: uterine tone (0-3), CL echogenicity (0-6), CL type (homogeneous, trabecular or anechoic center), luteal area (cm2), uterine echogenicity (0-3), uterine edema (0-3), luteal blood perfusion (0-100%) and uterine blood perfusion (1-4). Additionally, a blood sample was collected by puncture of the jugular vein for plasma P4 dosage. Retrospectively, recipients were classified according to the luteal area (small [≤ 6 cm2] or large [> 6 cm2]), luteal blood perfusion (low [≤ 55%] or high [> 55%]), and plasma concentration of P4 (low ≤ 9.98 ng/mL or high > 9.98 ng/mL). Pregnancy diagnosis was performed at 12 and 30 days of gestation. Luteal blood perfusion was significantly higher (P = 0.04) in pregnant recipients (n = 83) than in non-pregnant recipients (n = 27). Overall P/ET was higher (P ≤ 0.02) in mares with high luteal blood perfusion and high P4. Luteal blood perfusion was the most adequate significant (P = 0.01) predictor of pregnancy compared with the luteal area and plasma P4 concentration. Only luteal blood perfusion showed a linear (P = 0.03) and cubic (P = 0.004) effect on P/ET. In conclusion, CL blood perfusion determined by color-Doppler can be used in real-time to select recipients with the greatest chance of maintaining pregnancy in equine ET programs.
Glioblastoma (GBM) is the most common and severe form of brain cancer among adults. Its aggressiveness is largely attributed to its complex and heterogeneous biology that despite maximal surgery and multimodal chemoradiation treatment, inevitably recurs. Traditional large-scale profiling approaches have contributed substantially to the understanding of patient-to-patient inter-tumoral differences in GBM. However, it is now clear that biological differences within an individual (intra-tumoral heterogeneity) are also a prominent factor in treatment resistance and recurrence of GBM and will likely require integration of data from multiple recently developed omics platforms to fully unravel. Here we dissect the growing geospatial model of GBM, which layers intra-tumoral heterogeneity on a GBM stem cell (GSC) precursor, single cell, and spatial level. We discuss potential unique and inter-dependant aspects of the model including potential discordances between observed genotypes and phenotypes in GBM.
Progestin-primed ovarian stimulation (PPOS) is a new ovulation stimulation protocol, and its role in ovulation and regulatory mechanism is unclear. The clinical PPOS protocol was simulated in mice. The ovulated oocytes, estradiol, progesterone, and luteinizing hormone (LH) levels were analyzed at different hours after trigger. mRNA extraction and real-time PCR, hematoxylin and eosin staining, and immunofluorescence of ovaries were used to explore the involved signaling pathways. The PPOS group had a delayed ovulation at 12.5 h after trigger. Its suppressed LH level reduced the expression of luteinizing hormone/choriogonadotropin receptor (LHCGR) on the preovulatory follicles before trigger and significantly decreased the following progesterone synthesis, blood progesterone level, and progesterone receptor (PGR) expression within 4-6 h after trigger. Furthermore, the important ovulatory genes regulated by PGR including ADAMTS-1, VEGF-A, and EDN2 were downregulated, ultimately delaying the ovulation. PPOS suppresses the LH level before trigger and decreases the synthesis of progesterone after trigger, thus delaying the ovulation by downregulating the LHCGR-PGR pathway.
The existence of membrane-bound receptors provides a communicating bridge between the outside and inside of the cells through a hydrophobic membrane. In the central nervous system (CNS), receptor tyrosine kinase (RTK) is a large family of membrane-bound receptors that are involved in a wide variety of neuronal functions ranging from cell proliferation, differentiation, migration, metabolism, inflammation to cell apoptosis. These receptors have been shown to be implicated in the pathophysiology of neurodegenerative and psychiatric disorders. Therefore, RTKs may provide an important pharmacological target for the management and/or treatment of CNS disorders. This chapter describes the structural detail and classification of RTKs present in CNS, the signaling pathway associated with each class, and the involvement of RTKs particularly in neurodegenerative diseases and psychiatric disorders.
3D-QSAR models, molecular docking and MD simulations were performed to illustrate the relationship between different fields and the activities, which would be helpful in the design of more potent inhibitors.
Objectives:
Cardiovascular diseases are the leading cause of death worldwide, with patients having limited options for treatment. Pigment epithelium-derived factor (PEDF) is an endogenous multifunctional protein with several mechanisms of action. Recently, PEDF has emerged as a potential cardioprotective agent in response to myocardial infarction. However, PEDF is also associated with pro-apoptotic effects, complicating its role in cardioprotection. This review summarises and compares knowledge of PEDF's activity in cardiomyocytes with other cell types and draws links between them. Following this, the review offers a novel perspective of PEDF's therapeutic potential and recommends future directions to understand the clinical potential of PEDF better.
Key findings:
PEDF's mechanisms as a pro-apoptotic and pro-survival protein are not well understood, despite PEDF's implication in several physiological and pathological activities. However, recent evidence suggests that PEDF may have significant cardioprotective properties mediated by key regulators dependent on cell type and context.
Conclusions:
While PEDF's cardioprotective activity shares some key regulators with its apoptotic activity, cellular context and molecular features likely allow manipulation of PEDF's cellular activity, highlighting the importance of further investigation into its activities and its potential to be applied as a therapeutic to mitigate damage from a range of cardiac pathologies.
Objective
Unwanted angiogenesis is involved in the progression of various malignant tumors and cardiovascular diseases, and the factors that regulate angiogenesis are potential therapeutic targets. We tested the hypothesis that DCBLD1 (Discoidin, CUB, and LCCL domain-containing protein 1) is a co-receptor of VEGFR-2 and modulates angiogenesis in endothelial cells(ECs).
Approach and Results
A carotid artery ligation model and retinal angiogenesis assay were used to study angiogenesis using globe knockout or EC-specific conditional DCBLD1 knockout mice in vivo . Immunoblotting, immunofluorescence staining, plasma-membrane subfraction isolation, Co-immunoprecipitation and mass-spectrum assay were performed to clarify the molecular mechanisms.Loss of DCBLD1 impaired VEGF response and inhibited VEGF-induced EC proliferation and migration. DCBLD1 deletion interfered with adult and developmental angiogenesis. Mechanistically, DCBLD1 bound to VEGFR-2 and regulated the formation of VEGFR-2 complex with negative regulators: protein tyrosine phosphatases, E3 ubiquitin ligases(Nedd4 and c-Cbl), and also DCBLD1 knockdown promoted lysosome-mediated VEGFR-2 degradation in ECs.
Conclusions
These findings demonstrated the essential role of endothelial DCBLD1 in regulating VEGF signaling and provided evidence that DCBLD1 promotes VEGF-induced angiogenesis by limiting the dephosphorylation, ubiquitination, and lysosome degradation after VEGFR-2 endocytosis. We proposed that endothelial DCBLD1 is a potential therapeutic target for ischemic cardiovascular diseases by the modulation of angiogenesis through regulating of the VEGFR-2 endocytosis.
Angiogenesis plays a critical role in the survival, progression and metastasis of malignant tumors. Multiple factors are known to induce tumor angiogenesis, vascular endothelial growth factor (VEGF) is the most important one. Lenvatinib is an oral multi-kinase inhibitor of VEGFRs which has been approved for the treatment of various malignancies as the first-line agent by the Food and Drug Administration (FDA). It shows excellent antitumor efficacy in clinical practice. However, the adverse effects of Lenvatinib may seriously impair the therapeutic effect. Here we report the discovery and characterization of a novel VEGFR inhibitor (ZLF-095), which exhibited high activity and selectivity for VEGFR1/2/3. ZLF-095 displayed apparently antitumor effect in vitro and in vivo. We discovered that Lenvatinib could provoke fulminant ROS-caspase3-GSDME-dependent pyroptosis in GSDME-expressing cells by loss of mitochondrial membrane potential, which may be one of the reasons for Lenvatinib's toxicity. Meanwhile, ZLF-095 showed less toxicity than Lenvatinib by switching pyroptosis to apoptosis. These results suggest that ZLF-095 could become a potential angiogenesis inhibitor for cancer therapy.
Preovulatory follicle growth and the luteal transition require intense angiogenesis. This enables progesterone production to increase sufficiently to support a pregnancy. Inadequate follicular or luteal vascularisation can lead to reduced ovarian function and thus compromise fertility. Insulin-like growth factor 1 (IGF1) and IGF2 regulate multiple ovarian processes and are key links between an animal’s reproductive and metabolic status. This study investigated the role that the IGF system plays in regulating luteinising follicular endothelial cell (EC) networks and progesterone production in vitro. Bovine luteinising follicular angiogenesis cultures were treated with (i) LR³-IGF1 (10 or 100 ng/mL) under basal and angiogenic-stimulated conditions or (ii) IGF1 receptor (IGF1R) inhibitor (picropodophyllin (PPP); 1 µM) in the presence or absence of LR³-IGF1, IGF2 or combined LR³-IGF1 + IGF2 (10 ng/mL). EC networks were quantified by von Willebrand factor immunohistochemistry. Progesterone production was analysed by ELISA, and cell proliferation was determined by MTT assay. LR³-IGF1 had limited effects on EC growth parameters, whilst PPP (P < 0.001) markedly reduced EC growth parameters (by 60–70%). Cell proliferation was slightly increased (by 3–5%) by LR³-IGF1 (P < 0.001). LR³-IGF1 had variable effects on progesterone production, whilst PPP reduced progesterone concentration (P < 0.001) with or without LR³-IGF1 or IGF2 alone or in combination. IGF1 was detected in cell-conditioned media and was increased by LH (50 ng/mL) (P < 0.001). In conclusion, exogenous IGF1 and IGF2 had minimal effects on luteinising follicular angiogenesis and progesterone production, but the inhibitory effect of the IGF1R inhibitor (PPP) suggests that IGF1R signalling is critical for the development of EC networks and progesterone production in luteinising follicular cells.
Lay summary
The corpus luteum is a part of the ovary responsible for producing the critical pregnancy hormone, progesterone. To fulfil this function, the corpus luteum requires an extensive blood vessel network. Here, we investigated whether an important growth factor known to act on the ovary, insulin like growth factor (IGF) 1, critically regulates the formation of this blood vessel network and progesterone production. Cells from the corpus luteum were cultured with combinations of IGF1, a closely related hormone IGF2 and a chemical which stops both IGF1 and IGF2 from working. Afterwards, we measured the size and pattern of blood vessel networks, the production of progesterone and whether cells increased in number. We found adding IGF1 had limited effects, however stopping IGF1 from working had a very negative impact on both progesterone and on the formation of the blood vessel network. This suggests that cells from the corpus luteum were producing IGF1 and that IGF1/2 are critical for both blood vessel growth and hormone production.
Human vascular permeability factor (hVPF) is a glycoprotein that promotes fluid and protein leakage from blood vessels. The function of hVPF is at present unknown, but the potent bioactivities of this protein suggest that it could act during inflammation, wound healing, and tumor angiogenesis. hVPF was purified from serum-free conditioned medium of the human histiocytic lymphoma cell line U937 as a disulfide-linked dimeric 40-kDa protein that promoted dermal blood vessel leakage in guinea pigs at a dose of 20 ng (3 × 10⁻⁹ m) and promoted in vitro endothelial cell growth at concentrations as low as 50 pM. Multiple forms of hVPF with apparent pI values > 7.5 were resolved using pH gradient electrophoresis. Antibodies against guinea pig vascular permeability factor were found to cross-react with hVPF. The N-terminal amino acid sequence of hVPF was similar to, but not identical with, the N-terminal sequence of guinea pig vascular permeability factor.
Vascular endothelial growth factor (VEGF) is a homodimeric peptide growth factor which binds to two structurally related tyrosine kinase receptors denoted Flt1 and KDR. In order to compare the signal transduction via these two receptors, the human Flt1 and KDR proteins were stably expressed in porcine aortic endothelial cells. Binding analyses using 125I-VEGF revealed Kd values of 16 pM for Flt1 and 760 pM for KDR. Cultured human umbilical vein endothelial (HUVE) cells were found to express two distinct populations of binding sites with affinities similar to those for Flt1 and KDR, respectively. The KDR expressing cells showed striking changes in cell morphology, actin reorganization and membrane ruffling, chemotaxis and mitogenicity upon VEGF stimulation, whereas Flt1 expressing cells lacked such responses. KDR was found to undergo ligand-induced autophosphorylation in intact cells, and both Flt1 and KDR were phosphorylated in vitro in response to VEGF, however, KDR much more efficiently than Flt1. Neither the receptor-associated activity of phosphatidylinositol 3'-kinase nor tyrosine phosphorylation of phospholipase C-gamma were affected by stimulation of Flt1 or KDR expressing cells, and phosphorylation of GTPase activating protein was only slightly increased. Members of the Src family such as Fyn and Yes showed an increased level of phosphorylation upon VEGF stimulation of cells expressing Flt1 but not in cells expressing KDR. The maximal responses in KDR expressing porcine aortic endothelial cells were obtained at higher VEGF concentrations as compared to HUVE cells, i.e. in the presence of Flt1. This difference could possibly be explained by the formation of heterodimeric complexes between KDR and Flt1, or other molecules, in HUVE cells.
We have studied the role of the hypoxia-inducible angiogenic growth factor vascular endothelial growth factor (VEGF) in the induction and control of vessel growth in the developing retina of rats and cats, using in situ hybridization techniques. VEGF is expressed successively in two layers of neural retina, the innermost (axon) layer and the inner nuclear layer (INL). In the axon layer, VEGF is expressed transiently by astrocytes as they spread across the layer, closely preceding the formation of superficial vessels. In the INL, VEGF is expressed transiently by somas at the middle of the layer (presumably Muller cells), closely preceding the formation of the deep layer of retinal vessels. We propose that hypoxia caused by the onset of neuronal activity is detected by strategically located populations of neuroglia, first astrocytes, then Muller cells. In response they secrete VEGF, inducing formation of the superficial and deep layers of retinal vessels, respectively. As the vessels become patent, they relieve the hypoxic stimulus, so vessel formation is matched to oxygen demand. This hypothesis was tested experimentally in three ways. Expression of the high affinity flk-1 receptor for VEGF was demonstrated in newly formed retinal vessels, confirming that the secreted VEGF acts on the vessels, in a paracrine fashion. Direct hypoxic regulation of VEGF expression by macroglia was demonstrated in primary cultures of astrocytes and in cells of a glioma line. Hypoxic regulation of VEGF expression in the intact developing retina was demonstrated by showing that oxygen-enriched atmospheres that inhibit vessel formation also suppress endogenous VEGF production.
The vascular endothelial growth factor (VEGF) family encompasses four polypeptides that result from alternative splicing of mRNA. We have previously demonstrated differences in the secretion pattern of these polypeptides. Stable cell lines expressing VEGFs were established in human embryonic kidney CEN4 cells. VEGF121, the shortest form, was secreted and freely soluble in tissue culture medium. VEG189 was secreted, but was almost entirely bound to the cell surface or extracellular matrix. VEGF165 displayed an intermediary behavior. Suramin induced the release of VEGF189, permitting its characterization as a more basic protein with higher affinity for heparin than VEGF165 or VEGF121, but with similar endothelial cell mitogenic activity. Heparin, heparan sulfate, and heparinase all induced the release of VEGF165 and VEGF165 suggesting heparin-containing proteoglycans as candidate VEGF-binding sites. Finally, VEGF165 and VEGF189 were released from their bound states by treatment with plasmin. The released 34-kDa dimeric species are active as endothelial cell mitogens and as vascular permeability agents. We conclude that the bioavailability of VEGF may be regulated at the genetic level by alternative splicing that determines whether VEGF will be soluble or incorporated into a biological reservoir and also through proteolysis following plasminogen activation.
Vascular endothelial growth factor (VEGF) is a potent angiogenic factor and endothelial cell-specific mitogen that stimulates
urokinase-type plasminogen activator (uPA) activity in vascular endothelial cells. Here, we report that VEGF increases the
high affinity binding of uPA to the same cells and that this binding is prevented by a peptide corresponding to the uPA receptor
(uPAR) binding growth factor-like domain of uPA. Ligand cross-linking, ligand blotting, and uPA-Sepharose affinity chromatography
revealed an increase in a cell surface uPA binding protein that corresponds to the uPAR on the basis of its affinity for uPA,
Mrof 50,000-55,000, and phosphatidylinositol-specific phospholipase C sensitivity. By Scatchard analysis, VEGF increased the
number of uPAR molecules by 2.8-3.5-fold and concomitantly decreased their affinity for uPA. By northern blotting uPAR mRNA
was increased in a dose- and time-dependent manner in response to VEGF. Taken together, these findings demonstrate that VEGF-induced
angiogenesis is accompanied by increased uPAR expression and uPA activity on the endothelial cell surface. These observations
are consistent with the notion that the uPA-uPAR interaction facilitates cellular invasion.
The role of basic fibroblast growth factor-(bFGF) induced proteinases in basement membrane (BM) invasion by bovine capillary endothelial (BCE) cells was studied using a quantitative in vitro assay previously described (Mignatti et al., 1986). 125I-iododeoxyuridine-labeled BCE cells were grown for 72 h on the human amnion BM, and cell invasion was determined by measuring the radioactivity associated with the tissue after removal of the noninvasive cell layer. BCE cells were noninvasive under normal conditions. Addition of human bFGF to either the BM or to the stromal aspect of the amnion induced BCE cell invasion with a dose-dependent response. This effect was maximal in the presence of 70 ng/ml bFGF, and was inhibited by anti-FGF antibody. Transforming growth factor beta, as well as plasmin inhibitors and anti-tissue type plasminogen activator antibody inhibited BCE cell invasion. The tissue inhibitor of metalloproteinases, 1-10 phenanthroline, anti-type IV and anti-interstitial collagenase antibodies had the same effect. On the contrary, anti-stromelysin antibody and Eglin, an inhibitor of elastase, were ineffective. The results obtained show that both the plasminogen activator-plasmin system and specific collagenases are involved in the invasive process occurring during angiogenesis.
Although the importance of the vascular endothelial growth factor (VEGF)/VEGF tyrosine kinase receptor (VEGFR) system in angiogenesis is well established, very little is known about the regulation of VEGFR expression in vascular endothelial cells. We have cloned partial cDNAs encoding bovine VEGFR-1 (flt) and -2 (flk-1) and used them to study VEGFR expression by bovine microvascular- and large vessel-derived endothelial cells. Both cell lines express flk-1, but not flt. Transforming growth factor β1 (TGF-β1) reduced the high affinity I-VEGF binding capacity of both cell types in a dose-dependent manner, with a 2.0-2.7-fold decrease at 1-10 ng/ml. Cross-linking experiments revealed a decrease in I-VEGF binding to a cell surface monomeric protein corresponding to Flk-1 on the basis of its affinity for VEGF, molecular mass (185-190 kDa), and apparent internalization after VEGF binding. Immunoprecipitation and Western blot experiments demonstrated a decrease in Flk-1 protein expression, and TGF-β1 reduced flk-1 mRNA levels in a dose-dependent manner. These results imply that TGF-β1 is a major regulator of the VEGF/Flk-1 signal transduction pathway in endothelial cells.
Vascular endothelial cell growth factor (VEGF), an endothelial cell-specific mitogen that plays an important role in angiogenesis,
promotes the tyrosine phosphorylation of at least 11 proteins in bovine aortic endothelial cells (BAEC). Proteins immunoprecipitated
from lysates of control- and VEGF-stimulated BAEC with antisera to phospholipase C- (PLC-) were fractionated by SDS-polyacrylamide gel electrophoresis and transferred to Immobilon-P. Evaluation of the Western blots
with antisera to phosphotyrosine demonstrated that PLC- and two proteins (100 and 85 kDa) that associate with PLC- were phosphorylated in response to VEGF. By using antisera specific to other mediators of signal transduction that contain
SH2 domains for immunoprecipitation, it was demonstrated that VEGF promotes phosphorylation of phosphatidylinositol 3-kinase,
Ras GTPase activating protein (GAP), and the oncogenic adaptor protein NcK. Proteins of Mr consistent with the VEGF receptors Flt-1 and Flk-1/KDR were also tyrosine phosphorylated in stimulated cells. Tyrosine-phosphorylated
Nck, PLC-, and two GAP-associated proteins, p190 and p62, were in GAP immunoprecipitates of VEGF-stimulated BAEC, and tyrosine-phosphorylated
NcK was in phosphatidylinositol 3-kinase immunoprecipitates. These observations suggest that VEGF promotes formation of multimeric
aggregates of VEGF receptors with proteins that contain SH2 domains and activate various signaling pathways. VEGF-promoted
proliferation of endothelial cells and tyrosine phosphorylation of SH2 domain containing signaling molecules were inhibited
by the tyrosine kinase inhibitor genistein.
Vascular endothelial growth factor (VEGF) is a secreted angiogenic mitogen whose target cell specificity appears to be restricted to vascular endothelial cells. Such factors are likely candidates for regulatory molecules involved in endothelial growth control. We have characterized the murine VEGF gene and have analysed its expression pattern in embryogenesis, particularly during brain angiogenesis. Analysis of cDNA clones predicted the existence of three molecular forms of VEGF which differ in size due to heterogeneity at the carboxy terminus of the protein. The predicted mature proteins consist of 120, 164 or 188 amino acid residues. Homodimers of the two lower molecular weight forms, but not of the higher molecular weight form, were secreted by COS cells transfected with the corresponding cDNAs and were equally potent in stimulating the growth of endothelial cells. During brain development, VEGF transcript levels were abundant in the ventricular neuroectoderm of embryonic and postnatal brain when endothelial cells proliferate rapidly but were reduced in the adult when endothelial cell proliferation has ceased. The temporal and spatial expression of VEGF is consistent with the hypothesis that VEGF is synthesized and released by the ventricular neuroectoderm and may induce the ingrowth of capillaries from the perineural vascular plexus. In addition to the transient expression during brain development, a persistent expression of VEGF was observed in epithelial cells adjacent to fenestrated endothelium, e.g. in choroid plexus and in kidney glomeruli. The data are consistent with a role of VEGF as a multifunctional regulator of endothelial cell growth and differentiation.
We have used RT-PCR to screen pluripotent murine embryonic stem cells to identify receptor tyrosine kinases (RTKs) potentially involved in the determination or differentiation of cell lineages during early mouse development. Fourteen different tyrosine kinase sequences were identified. The expression patterns of four RTKs have been examined and all are expressed in the mouse embryo during, or shortly after, gastrulation. We report here the detailed expression pattern of one such RTK, the flt-related gene flk-1. In situ hybridization analysis of the late primitive streak stage embryo revealed that flk-1 was expressed in the proximal-lateral embryonic mesoderm; tissue fated to become heart. By headfold stages, staining was confined to the endocardial cells of the heart primordia as well as to the blood islands of the visceral yolk sac and the developing allantois. Patchy, speckled staining was detected in the endothelium of all the major embryonic and extraembryonic blood vessels as they formed. During early organogenesis, expression was detected in the blood vessels of highly vascularized tissues such as the brain, liver, lungs and placenta. Since flk-1 was expressed in early mesodermal cells prior to any morphological evidence for endothelial cell differentiation (vasculogenesis), as well as in cells that form blood vessels from preexisting ones (angiogenesis), it appears to be a very early marker of endothelial cell precursors. We have previously reported that another novel RTK, designated tek, was expressed in differentiating endothelial cells. We show here that flk-1 transcripts are expressed one full embryonic day earlier than the first tek transcripts. The expression of these two RTKs appear to correlate with the specification and early differentiation of the endothelial cell lineage respectively, and therefore may play important roles in the establishment of this lineage.
Treatment of human monocytes with vascular endothelial growth factor (VEGF) isolated from tumor cell supernatants was reported to induce monocyte activation and migration. In this study we show that recombinant human VEGF165, and VEGF121 had a maximal effect on human monocyte migration at 65 to 250 pmol/L. Chemotactic activity of VEGF165 was inhibited by a specific antiserum against VEGF, by heat treatment of VEGF165, and by protein kinase inhibitors. In addition, we could show that VEGF-stimulated monocyte migration is mediated by a pertussis toxin-sensitive GTP-binding protein. Placenta growth factor (PlGF152), a heparin-binding growth factor related to VEGF, was also chemotactic for monocytes at concentrations between 2.5 and 25 pmol/L. In accordance with these findings, human monocytes showed specific and saturable binding for 125I-VEGF165 (half-maximal binding at 1 to 1.5 nmol/L). Using Northern blot analysis, we further could show that human monocytes express only the gene for the VEGF receptor type, flt-1, but not for the second known VEGF receptor, KDR. Resting monocytes expressed low levels of flt-1 gene only. Brief exposure (2 to 4 hours) of human monocytes to lipopolysaccharide, a prototypic monocyte activator, led to a significant upregulation of the flt-1 mRNA level. The results presented here suggest that monocyte chemotaxis in response to VEGF and most likely to PlGF152 is mediated by flt-1 and thus show a possible function for the VEGF-receptor flt-1.
Angiogenesis, the sprouting of new blood vessels from pre-existing ones, and the permeability of blood vessels are regulated by vascular endothelial growth factor (VEGF) via its two known receptors Flt1 (VEGFR-1) and KDR/Flk-1 (VEGFR-2). The Flt4 receptor tyrosine kinase is related to the VEGF receptors, but does not bind VEGF and its expression becomes restricted mainly to lymphatic endothelia during development. In this study, we have purified the Flt4 ligand, VEGF-C, and cloned its cDNA from human prostatic carcinoma cells. While VEGF-C is homologous to other members of the VEGF/platelet derived growth factor (PDGF) family, its C-terminal half contains extra cysteine-rich motifs characteristic of a protein component of silk produced by the larval salivary glands of the midge, Chironomus tentans. VEGF-C is proteolytically processed, binds Flt4, which we rename as VEGFR-3 and induces tyrosine autophosphorylation of VEGFR-3 and VEGFR-2. In addition, VEGF-C stimulated the migration of bovine capillary endothelial cells in collagen gel. VEGF-C is thus a novel regulator of endothelia, and its effects may extend beyond the lymphatic system, where Flt4 is expressed.
We studied the distribution of messenger RNA (mRNA) that encodes for vascular endothelial growth factor (VEGF) within the primate ovary by in situ hybridization and Northern analysis to determine if the presence of mRNA for this angiogenic factor is associated with structures within the ovary in which angiogenesis is thought to play a role in development and/or function. In situ hybridization to sections of cynomolgus ovaries with a 35S-labeled antisense RNA probe revealed specific tissue localization within the follicle as well as the corpus luteum, but not stromal tissue. Intense expression of mRNA for VEGF during the late follicular phase was confined to the maturing follicle which, we presume, was destined for ovulation. Hybridization within the corpus luteum exhibited a punctate pattern suggesting that there may be specific cells within the corpus luteum that express mRNA for VEGF. The expression of mRNA for VEGF during the early and late luteal phase of the menstrual cycle was studied by Northern an...
Vascular endothelial growth factor (VEGF) expression in Various cell types is induced by hypoxia and other stimuli. VEGF mediates endothelial cell proliferation, angiogenesis, vascular growth, and vascular permeability via the endothelial cell receptors, kinase insert domain-containing receptor (KDR)/fetal liver kinase 1 (Flk-1) and FLT-1. Alanine-scanning mutagenesis was used to identify a positively charged surface in VEGF that mediates binding to KDR/Flk-1. Arg(82), Lys(84) and His(86), located in a hairpin loop, were found to be critical for binding KDR/Flk-1, while negatively charged residues, Asp(63), Glu(64), and Glu(67), were associated with FLT-1 binding. A VEGF model based on PDGFb indicated these positively and negatively charged regions are distal in the monomer but are spatially close in the dimer. Mutations within the KDR site had minimal effect on FLT-1 binding, and mutants deficient in FLT-1 binding did not affect KDR binding. Endothelial cell mitogenesis was abolished in mutants lacking KDR affinity; however, FLT-1 deficient mutants induced normal proliferation. These results suggest dual sets of determinants in the VEGF dimer that cross-link cell surface receptors, triggering endothelial cell growth and angiogenesis. Furthermore, this mutational analysis implicates KDR, but not FLT-1, in VEGF induction of endothelial cell proliferation.
Vascular endothelial growth factor (VEGF), a potent angiogenic factor and endothelial cell-specific mitogen, is up-regulated by hypoxia. However, the mechanism(s) responsible for hypoxic induction of VEGF has not been clearly delineated. We report that the steady state VEGF mRNA levels are increased 12 +/- 0.6-fold, but the transcriptional rate for VEGF is increased only 3.1 +/- O.6-fold by hypoxia in PC12 cells. In order to investigate cis-regulatory sequences which mediate this response to hypoxia, we cloned the rat genomic sequences encoding VEGF and identified a 28-base pair element in the 5' promoter that mediates hypoxia-inducible transcription in transient expression assays. This element has sequence and protein binding similarities to the hypoxia-inducible factor 1 binding site within the erythropoietin 3' enhancer. Post-transcriptional mechanisms have also been suggested to play a role in the hypoxic induction of VEGF. Evidence is provided that a frequently used polyadenylation site is 1.9 kilobases downstream from the translation termination codon for rat VEGF. This site is 1.5 kilobases further downstream from the polyadenylation site previously reported for VEGF. This new finding reveals sequence motifs in the 3'-untranslated region that may mediate VEGF mRNA stability.
Vascular endothelial growth factor (VEGF) is an endothelial cell mitogen that is thought to function by interacting with two high-affinity receptors, flk-1 and flt-1. In an adult heart, angiogenesis can occur in a number of pathological conditions, including atherosclerosis, hypertrophy, and infarction. To determine the role played by VEGF, flk-1, and flt-1 in this process in vive, we studied the expression of the growth factor and its receptors in a rat infarct model. After an acute myocardial infarction, we observed an initial rapid (1 h) rise in VEGF (275%), flk-1 (375%), and flt-1 (400%) mRNA expression throughout the entire heart. Initial diffuse induction of VEGF, flk-1, and flt-1 expression in the left ventricle was later replaced by an increase predominantly limited to perimyocardial infarction areas where angiogenesis was taking place. In situ hybridization showed at 6 h after infarction, viable myocytes adjacent to the infarct zone expressed markedly increased amounts of VEGF. At both 6 and 24 h, microvessels at the infarct edge overexpressed both flk-1 and flt-1 mRNAs; at 3 and 7 days new vessels infiltrating the infarct also overexpressed both receptors and continued for as late as 6 wk. In summary, acute myocardial infarction is accompanied by rapid and prolonged increase in expression of VEGF and its receptors with characteristic spatial and temporal kinetic. These findings suggest that the VEGF/VEGF receptor system plays an important role in the angiogenesis and stromal deposition associated with myocardial infarction.
• Basic fibroblast growth factor (FGF) is a potent endothelial cell mitogen that has been proposed to play a role in proliferative diabetic retinopathy and other neovascular processes. Our understanding of the in vivo role of basic FGF in the pathogenesis of these disorders is limited. We studied the immunolocalization of basic FGF in 16 clinical cases of diabetic retinopathy to determine whether the normal retinal distribution of basic FGF changed during the development of diabetic retinopathy and correlated with the onset of retinal neovascularization. By using monoclonal and affinity-purified polyclonal antibodies against basic FGF and heparan sulfate proteoglycan (HSPG), we found that basic FGF colocalized with HSPG to vascular basement membranes. As the basement membranes thickened during the progression of diabetic retinopathy, the intraretinal stores of immunoreactive basic FGF and HSPG expanded. With the development of neovascularization, the colocalization of basic FGF and HSPG changed; HSPG localized to basement membranes, while basic FGF localized intracellularly, with only minimal basement membrane immunoreactivity. Incubations of the neovascular fronds with exogenous basic FGF demonstrated multiple HSPG glycosaminoglycan-binding sites for basic FGF, indicating that basic FGF had not been released from the matrix of neovascular fronds by heparitanase digestion.
Objective:
To determine if the angiogenic peptide vascular endothelial growth factor (VEGF) is required for retinal ischemia—associated iris neovascularization in a nonhuman primate.Methods:
Laser retinal vein occlusion was used to produce retinal ischemia in 16 eyes of eight animals (Macaca fascicularis). Eyes were randomized to treatment every other day with intravitreal injections of either a neutralizing anti-VEGF monoclonal antibody or a control monoclonal antibody of the same isotype. Serial iris fluorescein angiograms were assessed using a standardized grading system and masked readers. Retinal VEGF and placental growth factor expression were assessed by Northern blotting. The specificity of the antibodies was determined in capillary endothelial cell proliferation assays prior to intravitreal injection.Results:
Zero of eight eyes receiving the neutralizing anti-VEGF antibodies developed iris neovascularization. Five of eight control antibody-treated eyes developed iris neovascularization. The difference was statistically significant (P=.03). Intravitreal antibody injection did not impair the ability of the ischemic retina to increase VEGF messenger RNA expression. The anti-VEGF antibodies specifically inhibited VEGF-driven capillary endothelial cell proliferation in vitro.Conclusion:
These data demonstrate that VEGF is required for iris neovascularization in an adult nonhuman primate eye. The inhibition of VEGF is a new potential therapeutic strategy for the treatment of ocular neovascularization.
We have previously suggested that tumor angiogenesis in human gliomas is regulated by a paracrine mechanism involving vascular endothelial growth factor (VEGF) and flt-I (VEGF-receptor I). VEGF, an endothelial-cell-specific mitogen, is abundantly expressed in glioma cells which reside along necrotic areas, whereas fit-I, a tyrosine-kinase receptor for VEGF, is expressed in tumor endothelial cells, but not in endothelial cells in normal adult brain. Recently, a second tyrosine-kinase receptor which binds VEGF with high affinity, designated KDR or flk-I, has been described. We performed in situ hybridization for VEGF mRNA, flt-I mRNA and KDR mRNA on serial sections of normal brain, low-grade and high-grade glioma specimens. We show that KDR mRNA is co-expressed with flt-I in vascular cells in glioblastoma but not in low-grade glioma. Since flt-I and KDR are not expressed in endothelial cells in the normal adult brain, the coordinate up-regulation of 2 receptors for VEGF appears to be a critical event which controls tumor angiogenesis. Immunocytochemistry with a monoclonal anti-VEGF antibody revealed significant amounts of VEGF protein in the same glioma cells that expressed VEGF mRNA. The largest amount of VEGF immunoreactivity, however, was detected on the vasculature of glioblastomas, the site where VEGF exerts its biological functions. These findings suggest that VEGF is produced and secreted by glioma cells and acts on tumor endothelial cells which express VEGF receptors. To further characterize VEGF-producer cells in vivo, we investigated cellular proliferation, immunoreactivity to the p53 tumor-suppressor gene product and epidermal-growth-factor-receptor(EGFR) expression on serial sections by immunocytochemistry. VEGF-producer cells did not show increased cellular proliferation, p53 immunoreactivity or EGFR immunoreactivity as compared with glioma cells which did not express VEGF. Our studies therefore do not demonstrate evidence for a growth advantage of VEGF-producer cells in vivo or VEGF induction by p53 mutation or EGFR over-expression. © 1994 Wiley-Liss, Inc.
Objective:
To study the involvement of eight angiogenic growth factors that have been identified so far in the literature, especially vascular endothelial growth factor, in proliferative diabetic retinopathy.Methods:
Samples of neovascular membranes were obtained from diabetic patients; these samples, excised at vitrectomy, were used to study the expression of messenger RNA of the angiogenic factors by using the method of the reverse transcription-polymerase chain reaction. Vitreous aspirates that were taken from diabetic and control patients were used to quantify vascular endothelial growth factor-like activity with a competitive radioreceptor assay.Results:
Of the eight angiogenic factors studied, vascular endothelial growth factor was the only one that was always expressed in the samples of neovascular membranes. Furthermore, vascular endothelial growth factor receptor-binding activity was greater in vitreous aspirates that were obtained from diabetic patients than in samples that were taken from control patients (P<.01).Conclusion:
Vascular endothelial growth factor seems to be an appropriate candidate for mediating retinal diabetic neovascularization.
The hypothesis that tumors are angiogenesis dependent has, in the past decade, generated new investigations designed to elucidate the mechanism of angiogenesis itself. Many laboratories are now engaged in this pursuit. Some are studying angiogenesis that occurs in physiological situations, whereas others are interested in angiogenesis that dominates pathological conditions. These efforts have led to (1) the development of bioassays for angiogenesis; (2) the partial purification and, in one case, the complete purification of angiogenic factors from neoplastic and non-neoplastic cells; (3) the development of new polymer technology for the sustained release of these factors and other macromolecules in vivo; (4) the cloning and long-term culture of capillary endothelial cells; (5) the demonstration of the role of nonendothelial cells, such as mast cells in modulating angiogenesis; (6) the discovery of angiogenesis inhibitors; and (7) the demonstration that certain animal tumors will regress when angiogenesis is inhibited. The effects of angiogenesis inhibitors provide perhaps the most compelling evidence for the role of angiogenesis in tumor growth. It is conceivable that the original effort to understand the role of angiogenesis in tumor growth will also lead to the use of angiogenesis inhibitors as a new class of pharmacologic agents in a variety of non-neoplastic diseases such as arthritis, psoriasis, and ocular neovascularization. However, much work remains to be done before it will be possible to understand (1) the regulatory systems that govern capillary density in normal tissues; (2) the factors that maintain the viability of microvascular endothelium; (3) the development of the vascular system itself; and (4) the mechanism by which vascular regression occurs, both in the embryo and in the postnatal organism. A knowledge of the mechanisms which underlie these normal processes may help to enlarge our comprehension of tumor angiogenesis.
A growth factor for vascular endothelial cells was identified in the media conditioned by bovine pituitary follicular cells and purified to homogeneity by a combination of ammonium sulfate precipitation, heparinsepharose affinity chromatography and two reversed phase HPLC steps. The growth factor was a cationic, heat stable and relatively acid stable protein and had a molecular weight, as assessed by silver-stained SDS-PAGE gel, of ∼45,000 under non reducing conditions and ∼23,000 under reducing conditions. The purified growth factor had a maximal mitogenic effect on adrenal cortex-derived capillary endothelial cells at the concentration of 1–1.2 ng/ml (22–26 pM). Further characterization of the bioactivity of the growth factor reveals that it exerts mitogenic effects also on vascular endothelial cells isolated from several districts but not on adrenal cortex cells, lens epithelial cells, corneal endothelial cells, keratynocytes or BHK-21 fibroblasts, indicating that its target cells specificity is unlike that of any previously characterized growth factor. Microsequencing reveals a unique N-terminal amino acid sequence. On the basis of its apparent target cell selectivity, we propose to name this factor vascular endothelial growth factor (VEGF).
Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), plays an important role in the increased vascular permeability and angiogenesis associated with many malignant tumors. In addition, VPF/VEGF is strongly expressed by epidermal keratinocytes in wound healing and psoriasis, disorders that are also characterized by increased microvascular permeability and angiogenesis. In this study, we investigated the expression of VPF/VEGF in three bullous diseases with subepidermal blister formation that are characterized by hyperpermeable dermal microvessels and pronounced papillary dermal edema. The expression of VPF/VEGF mRNA was strongly up-regulated in the lesional epidermis of bullous pemphigoid (n = 3), erythema multiforme (n = 3), and dermatitis herpetiformis (n = 4) as detected by in situ hybridization. Epidermal labeling was particularly intense over blisters, but strong expression was also noted in areas of the epidermis adjacent to dermal inflammatory infiltrates at a distance from blisters. Moreover, the VPF/VEGF receptors, fit-1 and KDR, were up-regulated in endothelial cells in superficial dermal microvessels. High levels of VPF/VEGF (138–238 pM) were detected in blister fluids obtained from five patients with bullous pemphigoid. Addition of blister fluid to human dermal microvascular endothelial cells exerted a dose-dependent mitogenic effect that was suppressed after depletion of VPF/VEGF by immunoadsorption. These findings strongly suggest that VPF/VEGF plays an important role in the induction of Increased microvascular permeability in bullous diseases, leading to papillary edema and fibrin deposition and contributing to the bulla formation characteristic of these disorders.
BACKGROUND
Solid tumors, including endometrial carcinomas, must induce a vascular stroma to grow beyond a minimal size. The mechanisms responsible for angiogenesis in endometrial carcinoma, however, are not well defined. Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a multifunctional cytokine that is an important regulator of tumor angiogenesis. We evaluated VPF/VEGF mRNA and protein expression, as well as VPF/VEGF receptor mRNA expression, in endometrial carcinoma.METHODS
Fourteen examples of endometrial carcinoma were evaluated by in situ hybridization; in 7 cases, benign atrophic endometrium from the same patient was also examined. Histologic sections were subjected to in situ hybridization using 35S-labeled riboprobes specific for VPF/VEGF and, in a subset of cases, riboprobes specific for the VPF/VEGF receptors flt-1 and KDR. In addition, ten examples of endometrial carcinoma were evaluated for VPF/VEGF protein expression by immunohistochemistry.RESULTSAll 14 examples of endometrial carcinoma studied by in situ hybridization exhibited focal strong VPF/VEGF mRNA expression by tumor cells. In addition, the endothelial cells of surrounding microvessels strongly expressed flt-1 and KDR mRNAs in all ten cases examined. In contrast, no strong expression of VPF/VEGF, flt-1, or KDR mRNA was observed in the seven examples of benign atrophic endometrium studied. All ten cases of endometrial carcinoma studied by immunohistochemistry exhibited strong VPF/VEGF protein expression by tumor cells.CONCLUSIONS
These observations suggest that VPF/VEGF is an important angiogenic factor in endometrial carcinoma. Cancer 1996;78:454-60.
Background:
Many studies have shown that angiogenesis plays an important role in the growth, progression, and metastasis of solid tumors. Recently, several angiogenic factors have been identified. Vascular endothelial growth factor (VEGF) is thought to be one such angiogenic factor and is also thought to be a selective mitogen for endothelial cells. We investigated the correlation between the expression of VEGF and the progression of gastric carcinoma.
Methods:
One hundred twenty-nine specimens resected from patients with gastric carcinoma were investigated by staining with a polyclonal antibody against VEGF. Correlations between the expression of VEGF, microvessel density, and various clincopathologic factors were studied.
Results:
Microvessel density, determined by immunostaining for Factor VIII related antigen, was significantly higher in VEGF-positive tumors than in VEGF-negative tumors. VEGF positivity was correlated with vessel involvement, lymph node metastasis, and liver metastasis. Moreover, patients with VEGF-positive tumors had a significantly poorer prognosis than those with VEGF-negative tumors. Multivariate analysis indicated that the expression of VEGF is an independent prognostic factor in patients with gastric cancer. According to the mode of recurrence, the frequency of hepatic metastases was significantly increased among patients with VEGF-positive tumors.
Conclusions:
The expression of VEGF may be a good prognostic indicator for patients with gastric carcinoma and may also be useful as a predictor of the mode of recurrence in patients with gastric carcinoma.
Animal models suggest a role for new vessel formation (angiogenesis) in tumours with metastatic potential, and there is some evidence that this is true for human tumours. What is needed is a sensitive and specific label for endothelial cells, and one candidate would be a monoclonal antibody to platelet/endothelial cell adhesion molecule (PECAM). We have counted microvessels in 103 primary breast cancers using the JC70 antibody to PECAM (or CD31). We compared our findings with various pathological indicators (lymph node status and tumour grade, size, and type and markers (oestrogen receptor, and c-erbB-2 expression and detection of mutant p53). Tumours showed significantly higher vascularisation than normal breast tissue and the number of blood vessels/mm2 was significantly associated with node metastasis. Only 2 out of 50 tumours with 99 vessel/mm2 or less were node positive whereas 31 out of 39 tumours with counts above 140/mm2 were positive (p<0·0001). Tumour size and grade also correlated with node metastasis and vascularisation also increased with the size of the primary and with poor differentiation. However, within each subgroup of size or differentiation tumours without node involvement had much lower vascular counts, and multivariate analysis showed that vascular count alone explains the association of size and grade with node metastasis. Other markers, conventional or novel, did not correlate with vascularisation. Even with the short follow-up in this series, vascular counts correlated with early death. These results suggest that angiogenesis is closely linked to metastasis, that it is acquired at a critical density of vessels, and that this process occurs as tumours enlarge or become more poorly differentiated. Counting of newly formed microvessels stained with endothelium-specific antibodies may prove to be a useful tool in the early detection of metastatic potential and in the selection of patients for whom anti-angiogenesis drugs might be beneficial.
To examine the potential involvement of vascular endothelial growth factor (VEGF) in vascular changes which occur in human intracranial neoplasms, we examined a series of tumor specimens for expression of VEGF mRNA by in situ hybridization. VEGF was expressed at high levels by tumor cells in discrete regions in several of the tumors examined. The highest levels were detected in glioblastomas. The presence and location of foci of intense VEGF mRNA expression were, paradoxically well correlated with the presence of necrobiosis within the tumor mass. A less consistent association was observed between VEGF expression and either the degree of vascularization or endothelial cell proliferation. Since VEGF has been shown to induce tissue factor expression, VEGF itself may be involved in the pathogenesis of necrosis. Our findings provide evidence that VEGF mRNA is highly expressed in specific intracranial malignancies and suggest that VEGF plays a complex and multifunctional role in vascular biology.
An understanding of the mechanisms regulating growth and differentiation of vascular endothelial cells is very important for cardiovascular biology and medicine. Several potential regulators of angiogenesis have been identified, including acidic and basic fibroblast growth factors, epidermal growth factor, platelet-derived endothelial cell growth factor, transforming growth factors α and β, and tumor necrosis factor α (TNF-α). Vascular endothelial growth factor (VEGF) is unique among these agents by virtue of its direct and specific mitogenic effects on endothelial cells combined with the fact that it is a secreted polypeptide. By alternative splicing of mRNA, VEGF may exist in four different isoforms that have similar biologic activities but differ markedly in their secretion pattern. VEGF is emerging as an important regulator of developmental and ovarian angiogenesis. Its action is purely paracrine as it is produced by a variety of cell types, but its receptors are only in endothelial cells. There is no evidence that endothelial cells in vivo produce VEGF. The VEGF mRNA is expressed at high level by a variety of human tumors, suggesting that VEGF may be a tumor angiogenesis factor. This hypothesis is supported by the finding that monoclonal antibodies specific for VEGF are able to suppress tumor growth in vivo. Therefore, VEGF antagonists may be used for the treatment of malignancies and, possibly, other angiogenic diseases. The VEGF protein has therapeutic potential as an inducer of neovascularization in conditions characterized by impaired tissue perfusion like obstructive atherosclerosis.