Vascular endothelial growth factor induces the migration of human airway smooth muscle cells by activating the RhoA/ROCK pathway

BACKGROUND

Airway remodeling due to increased airway smooth muscle cell (ASMC) mass, likely due to enhanced proliferation, hypertrophy, and migration, has been proven to be highly correlated with decreased lung function in asthma patients. Vascular endothelial growth factor (VEGF) mediates vascular and extravascular remodeling and inflammation and has been proven to be involved in the progression of asthma. Previous studies have focused on the effects of VEGF on ASMC proliferation, but few researchers have focused on the effects of VEGF on human ASMC migration. The purpose of this study was to explore the effect of VEGF on the migration of ASMCs and its related signaling pathway mechanism to provide evidence for the treatment of airway remodeling.

METHODS

We examined the effects of VEGF induction on ASMC migration and explored the mechanisms involved in ASMC migration.

RESULTS

We found by wound healing and Transwell assays that VEGF promoted ASMC migration. Through the Cell Counting Kit-8 (CCK-8) experiment, we found that VEGF had no significant effect on the proliferation of ASMCs, which excluded the involvement of cell proliferation in the process of wound healing. Moreover, a cellular immunofluorescence assay showed that VEGF promoted F-actin reorganization, and Western blotting showed that VEGF improved RhoA activation and myosin phosphatase targeting subunit-1 (MYPT1) and myosin light chain (MLC) phosphorylation in ASMCs. Treatment with the ROCK inhibitor Y27632 significantly attenuated the effects of VEGF on MYPT1/MLC activation and cell migration.

CONCLUSION

In conclusion, the results suggest that the promigratory function of VEGF activates the RhoA/ROCK pathway, induces F-actin reorganization, improves the migration of ASMCs, and provides a better rationale for targeting the RhoA/ROCK pathway for therapeutic approaches in airway remodeling.

BMECs Ameliorate High Glucose-Induced Morphological Aberrations and Synaptic Dysfunction via VEGF-Mediated Modulation of Glucose Uptake in Cortical Neurons

It has been demonstrated that diabetes cause neurite degeneration in the brain and cognitive impairment and neurovascular interactions are crucial for maintaining brain function. However, the role of vascular endothelial cells in neurite outgrowth and synaptic formation in diabetic brain is still unclear. Therefore, present study investigated effects of brain microvascular endothelial cells (BMECs) on high glucose (HG)-induced neuritic dystrophy using a coculture model of BMECs with neurons. Multiple immunofluorescence labelling and western blot analysis were used to detect neurite outgrowth and synapsis formation, and living cell imaging was used to detect uptake function of neuronal glucose transporters. We found cocultured with BMECs significantly reduced HG-induced inhibition of neurites outgrowth (including length and branch formation) and delayed presynaptic and postsynaptic development, as well as reduction of neuronal glucose uptake capacity, which was prevented by pre-treatment with SU1498, a vascular endothelial growth factor (VEGF) receptor antagonist. To analyse the possible mechanism, we collected BMECs cultured condition medium (B-CM) to treat the neurons under HG culture condition. The results showed that B-CM showed the same effects as BMEC on HG-treated neurons. Furthermore, we observed VEGF administration could ameliorate HG-induced neuronal morphology aberrations. Putting together, present results suggest that cerebral microvascular endothelial cells protect against hyperglycaemia-induced neuritic dystrophy and restorate neuronal glucose uptake capacity by activation of VEGF receptors and endothelial VEGF release. This result help us to understand important roles of neurovascular coupling in pathogenesis of diabetic brain, providing a new strategy to study therapy or prevention for diabetic dementia. Hyperglycaemia induced inhibition of neuronal glucose uptake and impaired to neuritic outgrowth and synaptogenesis. Cocultured with BMECs/B-CM and VEGF treatment protected HG-induced inhibition of glucose uptake and neuritic outgrowth and synaptogenesis, which was antagonized by blockade of VEGF receptors. Reduction of glucose uptake may further deteriorate impairment of neurites outgrowth and synaptogenesis.

Utilization of response surface design for development and optimization of rosuvastatin calcium-loaded nano-squarticles for hair growth stimulating VEGF and IGF production: in-vitro and in-vivo evaluation

INTRODUCTION

Countless individuals experience negative emotions as hair loss pattern affects their self-esteem and well-being. Rosuvastatin calcium (Ca-RUV) was reported to stimulate the growth of the hair in the applied area, hence, it was selected as a potential hair loss treatment drug.

SIGNIFICANCE

This study aims to develop and optimize (Ca-RUV) loaded squarticles (SQRs) and assess their ability to deliver and release Ca-RUV in the hair follicle for the promotion of hair growth.

METHODS

A response surface design was utilized to study the effect of varying Pluronic® F68 (PF68) and the percentage of liquid lipids within the core of the SQRs and the effects of particle size, entrapment efficiency, and drug released percentage after 24 h (%Q24) were assessed. The optimized formula was subjected to DSC, XRD, and in-vivo evaluation in rats.

RESULTS

SQRs stabilized by 0.8% PF68 and contained 37.5% liquid lipids showed an acceptable particle size (250 nm), drug entrapment efficiency (75%), and %Q24 (100%). The in-vivo studies illustrated the ability of the formula to regrow hair in animals after 10 days due to the elevation of the vascular endothelial growth factor (VEGF) and insulin-like growth factor 1 (IGF-1) to their normal values and by 9% and 54%, respectively, relative to standard therapy minoxidil (5%).

CONCLUSION

Thus, it can be concluded that the optimized formula of Ca-RUV loaded SQRs showed superior in-vivo results in the promotion of hair growth in a shorter period relative to the marketed product. Therefore, the formula can offer a viable option for the treatment of hair loss.

Effect of chlorpyrifos on VEGF gene expression

Chlorpyrifos (CPF; 0,0-diethyl 0-(3,5,6-trichloro-2-pyridinyl)-phosphorothioate), a cholinesterase inhibitor, compromised the integrity of the blood-brain barrier (BBB) when used at low concentrations during our previous experiments in vitro. To determine if BBB leakage would also occur in vivo, we used FITC-dextrans to evaluate BBB permeability in CPF-dosed mice. Results indicated BBB leakages that were evident at 2 h after treatment with 70 mg/kg CPF ip. Since vascular endothelial growth factor (VEGF), a potent vasopermeability factor, is a signaling protein that promotes the growth of new blood vessels, we investigated the possible involvement of VEGF in BBB disruption by CPF. We found that VEGF serum concentration was significantly increased at 24 h after CPF exposure. To further explore VEGF involving BBB disruption by CPF treatment, the receptor antagonist for VEGF (sFlt-1) was used for pretreatment before CPF exposure. After sFlt-1 pretreatment, gene expressions of the tight junction (TJ) proteins claudin5 and occludin were significantly downregulated at 1, 2, and 3 h, but returned to control levels at 24 h after CPF treatment. These results suggest that VEGF is involved in BBB disruption by CPF through BBB-TJs regulation.

Fenugreek Seed Extract Regulates Human Umbilical Vein Endothelial Cell Angiogenesis and Proliferation via the PI3K/Akt/Cyclin D1 Pathway

The significance of angiogenesis in tumour progression has been widely documented. Hence, the identification of anti-angiogenic agents with fewer common side effects would be valuable in cancer therapy. In this study, we evaluated the anti-angiogenic and anti-proliferative effects of a hydro-alcoholic extract of fenugreek seed (HAEF) on human umbilical vein endothelial cells (HUVECs). Human umbilical vein endothelial cells were treated with various concentrations of HAEF and the half-maximal inhibitory concentration (IC50) value was estimated by using the MTT assay. Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and matrix metalloproteinase enzyme (MMP-2 and MMP-9) gene expression profiles were evaluated by using quantitative RT-PCR (qRT-PCR). Moreover, MMP activities and PI3K, Akt and cyclin D1 protein expression levels were evaluated by gel zymography and Western blotting, respectively. HAEF reduced HUVEC viability, with an IC50 value of 200 μg/ml. The qRT-PCR results demonstrated that treatment with HAEF markedly reduced MMP-2/MMP-9, VEGF and bFGF gene expression, as compared to the control group. We also found that MMP-2/MMP-9 enzyme activity and PI3K/Akt/cyclin D1 protein expression were notably decreased in cells treated with HAEF. Our results suggest that HAEF can potentially inhibit angiogenesis, and also affect cellular proliferation by targeting the PI3K/Akt/cyclin D1 pathway. Thus, fenugreek seed extract merits further investigation as a source of compounds with anti-cancer properties.

Single-Cell RNA-Seq Reveals LRRC75A-Expressing Cell Population Involved in VEGF Secretion of Multipotent Mesenchymal Stromal/Stem Cells Under Ischemia

Human multipotent mesenchymal stromal/stem cells (MSCs) have been utilized in cell therapy for various diseases and their clinical applications are expected to increase in the future. However, the variation in MSC-based product quality due to the MSC heterogeneity has resulted in significant constraints in the clinical utility of MSCs. Therefore, we hypothesized that it might be important to identify and ensure/enrich suitable cell subpopulations for therapies using MSC-based products. In this study, we aimed to identify functional cell subpopulations to predict the efficacy of angiogenic therapy using bone marrow-derived MSCs (BM-MSCs). To assess its angiogenic potency, we observed various levels of vascular endothelial growth factor (VEGF) secretion among 11 donor-derived BM-MSC lines under in vitro ischemic culture conditions. Next, by clarifying the heterogeneity of BM-MSCs using single-cell RNA-sequencing analysis, we identified a functional cell subpopulation that contributed to the overall VEGF production in BM-MSC lines under ischemic conditions. We also found that leucine-rich repeat-containing 75A (LRRC75A) was more highly expressed in this cell subpopulation than in the others. Importantly, knockdown of LRRC75A using small interfering RNA resulted in significant inhibition of VEGF secretion in ischemic BM-MSCs, indicating that LRRC75A regulates VEGF secretion under ischemic conditions. Therefore, LRRC75A may be a useful biomarker to identify cell subpopulations that contribute to the angiogenic effects of BM-MSCs. Our work provides evidence that a strategy based on single-cell transcriptome profiles is effective for identifying functional cell subpopulations in heterogeneous MSC-based products.

Upregulated miR-194-5p suppresses retinal microvascular endothelial cell dysfunction and mitigates the symptoms of hypertensive retinopathy in mice by targeting SOX17 and VEGF signaling

BACKGROUND

Hypertensive retinopathy (HR) is a retinal disease that may lead to vision loss and blindness. Sex-determining region Y (SRY)-box (SOX) family transcription factors have been reported to be involved in HR development. In this study, the role and upstream mechanism of SRY-box transcription factor 17 (SOX17) in HR pathogenesis were investigated.

METHODS

SOX17 and miR-194-5p levels in Angiotensin II (Ang II)-stimulated human retinal microvascular endothelial cells (HRMECs) and retinas of mice were detected by RT-qPCR. SOX17 protein level as well as levels of tight junction proteins and vascular endothelial growth factor (VEGF) signaling-associated proteins were quantified by western blotting. Tube formation assays were performed to evaluate angiogenesis in HRMECs. The structure of mouse retinal tissues was observed by H&E staining. The interaction between miR-194-5p and SOX17 was confirmed by a luciferase reporter assay.

RESULTS

SOX17 was upregulated in HRMECs treated with Ang II. SOX17 knockdown inhibited angiogenesis in Ang II-stimulated HRMECs and increased tight junction protein levels. Mechanically, SOX17 was targeted by miR-194-5p. Moreover, miR-194-5p upregulation restrained angiogenesis and increased tight junction protein levels in Ang II-treated HRMECs, and the effect was reversed by SOX17 overexpression. MiR-194-5p elevation inactivated VEGF signaling via targeting SOX17. miR-194-5p alleviated pathological symptoms of HR in Ang II-treated mice, and its expression was negatively correlated with SOX17 expression in the retinas of model mice.

CONCLUSIONS

MiR-194-5p upregulation suppressed Ang II-stimulated HRMEC dysfunction and mitigates the symptoms of HR in mice by regulating the SOX17/VEGF signaling.

Platycodin D Inhibits Vascular Endothelial Growth Factor-Induced Angiogenesis by Blocking the Activation of Mitogen-Activated Protein Kinases and the Production of Interleukin-8

Platycodin D is a major constituent in the root of Platycodon grandiflorum and has diverse pharmacologic activities, including anti-inflammatory, anti-allergic, and antitumor activities. Vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) are potent angiogenic factors and contribute to tumor angiogenesis by directly and indirectly promoting angiogenic processes, including the proliferation, adhesion, migration, and tube formation of endothelial cells. Here, we found that platycodin D at noncytotoxic concentrations inhibited VEGF-induced proliferation, adhesion to the extracellular matrix proteins fibronectin and vitronectin, chemotactic motility, and tube formation of human umbilical vein endothelial cells (HUVECs). Platycodin D reduced the phosphorylation of extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK) and the secretion of IL-8 in VEGF-stimulated HUVECs. Moreover, platycodin D inhibited tube formation and the phosphorylation of ERK and p38 in IL-8-stimulated HUVECs. The in vitro anti-angiogenic activity of platycodin D was confirmed by in vivo experimental models. Platycodin D inhibited the formation of new blood vessels into mouse Matrigel plugs with VEGF or IL-8. In mice injected with MDA-MB-231 human breast cancer cells, orally administered platycodin D inhibited tumor growth, the number of CD34 [Formula: see text]vessels, and the expression of VEGF and IL-8. Taken together, platycodin D directly and indirectly prevents VEGF-induced and IL-8-induced angiogenesis by blocking the activation of mitogen-activated protein kinases (MAPKs). Platycodin D may be beneficial for the prevention or treatment of tumor angiogenesis and angiogenesis-related human diseases.

Two-year outcomes of episcleral brachytherapy adjunct to anti-VEGF therapy for treatment-resistant nAMD

PURPOSE

This study was designed to demonstrate the safety and feasibility of episcleral brachytherapy (ESB) for the treatment of anti-vascular endothelial growth factor (anti-VEGF) resistant neovascular age-related macular degeneration (nAMD) in a 6-subject cohort adjunct to anti-VEGF therapy.

METHODS

Six eyes of six subjects with anti-VEGF resistant nAMD (persistent fluid or hemorrhage despite frequent anti-VEGF treatment) were treated with ESB between May 2018 and July 2018 as part of a larger early feasibility trial. Baseline and follow-up exams with multi-modal imaging were conducted.

RESULTS

In this analysis, six eyes were included. The mean age was 74.7 years; 33% were female; 67% had polypoidal choroidal vasculopathy. The mean number of lifetime anti-VEGF injections received prior to the study enrollment was 33.9 injections and 10 injections in the year prior to the study enrollment. In the first and second years following ESB, the mean number of injections was 8.5 and 8, respectively. No evidence of radiation-induced toxicity through 2 years following ESB was observed. The mean baseline VA was 55.3 letters. At 1 year, the mean VA increased by 3.2 letters and 1.7 letters at year 2. At 2 years, the mean change in vascular complex on ICGA was - 18%, - 43% on OCTA, and - 5% on FA. The subjects also experienced a mean decrease in CRT on OCT of 21% after 2 years.

CONCLUSIONS

The results from this six-subject cohort with 2-year data support additional investigations of ESB for nAMD, specifically those with persistent disease activity and treatment resistant nAMD.

Endothelial Phospholipase Cγ2 Improves Outcomes of Diabetic Ischemic Limb Rescue Following VEGF Therapy

Therapeutic vascular endothelial growth factor (VEGF) replenishment has met with limited success for the management of critical limb-threatening ischemia. To improve outcomes of VEGF therapy, we applied single-cell RNA sequencing (scRNA-seq) technology to study the endothelial cells of the human diabetic skin. Single-cell suspensions were generated from the human skin followed by cDNA preparation using the Chromium Next GEM Single-cell 3' Kit v3.1. Using appropriate quality control measures, 36,487 cells were chosen for downstream analysis. scRNA-seq studies identified that although VEGF signaling was not significantly altered in diabetic versus nondiabetic skin, phospholipase Cγ2 (PLCγ2) was downregulated. The significance of PLCγ2 in VEGF-mediated increase in endothelial cell metabolism and function was assessed in cultured human microvascular endothelial cells. In these cells, VEGF enhanced mitochondrial function, as indicated by elevation in oxygen consumption rate and extracellular acidification rate. The VEGF-dependent increase in cell metabolism was blunted in response to PLCγ2 inhibition. Follow-up rescue studies therefore focused on understanding the significance of VEGF therapy in presence or absence of endothelial PLCγ2 in type 1 (streptozotocin-injected) and type 2 (db/db) diabetic ischemic tissue. Nonviral topical tissue nanotransfection technology (TNT) delivery of CDH5 promoter-driven PLCγ2 open reading frame promoted the rescue of hindlimb ischemia in diabetic mice. Improvement of blood flow was also associated with higher abundance of VWF+/CD31+ and VWF+/SMA+ immunohistochemical staining. TNT-based gene delivery was not associated with tissue edema, a commonly noted complication associated with proangiogenic gene therapies. Taken together, our study demonstrates that TNT-mediated delivery of endothelial PLCγ2, as part of combination gene therapy, is effective in diabetic ischemic limb rescue.

Circular RNA circ_0002984 Promotes Cell Proliferation and Migration by Regulating miR-181b-5p/Vascular Endothelial Growth Factor Axis and PI3K-AKT Signaling Pathway in Oxidized Low-Density Lipoprotein-Treated Vascular Smooth Muscle Cells

ABSTRACT

RNAs (circRNAs) play critical roles in many diseases, including atherosclerosis (AS). However, the role and underlying mechanism of circ_0002984 in AS remain unclear. Vascular smooth muscle cells (VSMCs) treated with oxidized low-density lipoprotein (ox-LDL) were used as a AS cell model. Quantitative real-time polymerase chain reaction was conducted to detect the expression of circ_0002984, miR-181b-5p and vascular endothelial growth factor A (VEGFA). Cell proliferation was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide assay and 5-ethynyl-2'-deoxyuridine assays. Cell migration was assessed using wound healing assay and transwell assay. All protein levels were analyzed by western blot assay. The interaction between miR-181b-5p and circ_0002984 or VEGFA was confirmed by dual-luciferase reporter, RNA Immunoprecipitation, and RNA pull-down assays. Circ_0002984 and VEGFA were overexpressed, and miR-181b-5p was downregulated in serum of AS patients and ox-LDL-stimulated VSMCs. Circ_0002984 silencing inhibited ox-LDL-induced proliferation and migration in VSMCs. MiR-181b-5p was a target of circ_0002984, and miR-181b-5p inhibition counteracted the suppressing effects of circ_0002984 downregulation on proliferation and migration in ox-LDL-stimulated VSMCs. Additionally, VEGFA was a downstream target of miR-181b-5p and VEGFA upregulation abolished the suppressive influence of miR-181b-5p on proliferation and migration in ox-LDL-exposed VSMCs. Furthermore, circ_0002984 depletion blocked phosphatidylinositol 3 kinase-AKT signaling pathway by regulating miR-181b-5p and VEGFA. Circ_0002984 downregulation suppressed cell proliferation and migration by regulating miR-181b-5p/VEGFA axis and phosphatidylinositol 3 kinase-AKT pathway in ox-LDL-stimulated VEGFA, providing a new mechanism for AS pathogenesis.

Platelet-rich plasma exhibits anti-inflammatory effect and attenuates cardiomyocyte damage by reducing NF-κB and enhancing VEGF expression in isoproterenol induced cardiotoxicity model

The present study investigated the cardioprotective effects of activated platelet-rich plasma (PRP) on high dose isoproterenol (ISO) induced cardiotoxicity. ISO was injected at a dose of 85 mg/kg/day, s.c. for 2 days. Cardiac function parameters including dp/dt max/min, left ventricular end diastolic pressure (LVEDP), relaxation constant (tau) and electrocardiogram (ECG) changes, anti-oxidant and membrane bound enzymes assays, pro-inflammatory cytokine levels, collagen content, immunohistochemical staining/gene expression of vascular endothelial growth factor (VEGF), cTnI (cardiac troponin I), NF-κB (nuclear factor kappa B), Smad-2/3, TGF-β (transforming growth factor), collagen-1/3 proteins were evaluated. PRP and platelet-poor plasma (PPP) were injected intramyocardially (200 μl in each ventricle region) 3 h after first dose of ISO under anesthesia. ISO injection induced cardiac dysfunction, hypertrophy, fibrosis, necrosis due to decline in anti-oxidant capacity, enhanced NF-κB and reduced cTnI immunostaining. However, the PRP injection attenuated these cardiac pathological changes by exerting anti-inflammatory properties and promoting cardiomyocyte repair.

PHD2 attenuates high-glucose-induced blood retinal barrier breakdown in human retinal microvascular endothelial cells by regulating the Hif-1α/VEGF pathway

OBJECTIVE

Diabetic macular edema (DME) is one of the most frequent causes of severe vision loss. The pathogenesis of DME is still not fully understood; however, it is hypothesized to result from breakdown of the blood-retinal barrier (BRB) due to retinal inflammation by vascular endothelial growth factor (VEGF) secretion under hyperglycemic conditions. In this investigation, we discovered that Prolyl-4-hydroxylase 2 (PHD2), an upstream regulator of hypoxia-inducible factor 1 (HIF-1) modulates VEGF expression and thus preserves BRB function in the mouse retina.

MATERIALS AND METHODS

Primary human retinal microvascular endothelial cells (hRMECs) were cultured in human endothelial serum-free growth medium and exposed to hyperglycemia. Changes in cell viability were investigated by an MTT assay. BRB function in each group was revealed by a paracellular permeability assay and trans-endothelial electrical resistance (TEER). Morphological changes in the BRB were investigated by immunofluorescence staining of occludin and zonula occludens-1 (ZO-1). The mRNA and protein levels of the tight junction proteins, PHD2, HIF-1α, and VEGF were measured by reverse transcription-quantitative PCR (RT-qPCR), western blot analysis and ELISA.

RESULTS

Under hyperglycemic conditions, the viability of hRMECs was decreased, and PHD2 expression was downregulated, accompanied by increased paracellular permeability and decreased trans-endothelial electrical resistance. Additionally, HIF-1α and VEGF expression levels were increased, whereas the expression levels of tight junction proteins, including occludin and ZO-1, were decreased and BRB function was compromised. The PHD2 activator R59949 (diacylglycerol kinase inhibitor II), altered these pathological changes, and the PHD2 inhibitor dimethyloxalylglycine (DMOG) resulted in the opposite effects.

CONCLUSION

These results demonstrated that PHD2 inhibited HIF-1 activity by inhibiting HIF-1α expression in hRMECs under hyperglycemic conditions, which led to the downregulation of the expression of the angiogenic factor VEGF, and thus helped to maintain the functions of hRMECs. Therefore, it is reasonable to propose that PHD2 could be a potential novel target for the treatment of DME or other diseases with a similar pathogenesis.

Epicardial delivery of XC001 gene therapy for refractory angina coronary treatment (The EXACT Trial): Rationale, design, and clinical considerations

BACKGROUND

Patients with refractory angina (RA) have poor quality of life and new therapies are needed. XC001 is a novel adenoviral vector expressing multiple isoforms of vascular endothelial growth factor (VEGF) promoting an enhanced local angiogenic effect.

METHODS

The Epicardial Delivery of XC001 Gene Therapy for Refractory Angina Coronary Treatment (EXACT) trial is a 6-month (with 6-month extension) phase 1/2, first-in-human, multicenter, open-label, single-arm, dose-escalation study to evaluate the safety, tolerability, and preliminary efficacy of XC001 in patients with RA. The trial will enroll 33 patients in an initial (n = 12) ascending dose-escalation phase (1 × 10⁹, 1 × 10¹⁰, 4 × 10¹⁰, and 1 × 10¹¹ viral particles), followed by phase 2 (n = 21) assessing the highest tolerated dose. Patients must have stable Canadian Cardiovascular Society (CCS) class II-IV angina on maximally tolerated medical therapy without options for conventional revascularization, demonstrable ischemia on stress testing, and angina limiting exercise tolerance. XC001 will be delivered directly to ischemic myocardium via surgical transthoracic epicardial access. The primary outcome is safety via adverse event monitoring through 6 months. Efficacy assessments include difference from baseline to month 6 in time to 1 mm of ST segment depression, time to angina, and total exercise duration; myocardial blood flow at rest, and stress and coronary flow reserve by positron emission tomography; quality of life; CCS functional class; and angina frequency.

CONCLUSIONS

The EXACT trial will determine whether direct intramyocardial administration of XC001 in patients with RA is safe and evaluate its effect on exercise tolerance, myocardial perfusion, angina and physical activity, informing future clinical investigation.

CLINICAL TRIAL REGISTRATION

NCT04125732.

Endothelial Semaphorin 3fb regulates Vegf pathway-mediated angiogenic sprouting

Vessel growth integrates diverse extrinsic signals with intrinsic signaling cascades to coordinate cell migration and sprouting morphogenesis. The pro-angiogenic effects of Vascular Endothelial Growth Factor (VEGF) are carefully controlled during sprouting to generate an efficiently patterned vascular network. We identify crosstalk between VEGF signaling and that of the secreted ligand Semaphorin 3fb (Sema3fb), one of two zebrafish paralogs of mammalian Sema3F. The sema3fb gene is expressed by endothelial cells in actively sprouting vessels. Loss of sema3fb results in abnormally wide and stunted intersegmental vessel artery sprouts. Although the sprouts initiate at the correct developmental time, they have a reduced migration speed. These sprouts have persistent filopodia and abnormally spaced nuclei suggesting dysregulated control of actin assembly. sema3fb mutants show simultaneously higher expression of pro-angiogenic (VEGF receptor 2 (vegfr2) and delta-like 4 (dll4)) and anti-angiogenic (soluble VEGF receptor 1 (svegfr1)/ soluble Fms Related Receptor Tyrosine Kinase 1 (sflt1)) pathway components. We show increased phospho-ERK staining in migrating angioblasts, consistent with enhanced Vegf activity. Reducing Vegfr2 kinase activity in sema3fb mutants rescues angiogenic sprouting. Our data suggest that Sema3fb plays a critical role in promoting endothelial sprouting through modulating the VEGF signaling pathway, acting as an autocrine cue that modulates intrinsic growth factor signaling.

Changes in inner retinal layer thickness in patients with exudative age-related macular degeneration during treatment with anti-vascular endothelial growth factor

The aim of this study was to identify any changes that occur in the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) in patients with exudative age-related macular degeneration (AMD) during treatment with anti-vascular endothelial growth factor (VEGF) injections.Patients were enrolled in this retrospective study if they had exudative AMD, had received at least 3 injections of ranibizumab or aflibercept, and had a minimum of 12 months of follow-up. We analyzed the changes in the RNFL and GC-IPL using spectral-domain optical coherence tomography in rescan mode.Fifty-two eyes of 52 patients who had been treated with repeated anti-VEGF injections for exudative AMD were included. At the final visit, there was no significant between-group difference in best-corrected visual acuity or intraocular pressure. There was a significant decrease in central macular thickness in all groups (P < .05). There was a decrease in RNFL thickness that was only statistically significant in the ranibizumab group and when the ranibizumab or aflibercept groups were combined (P = .036 and .044, respectively). The thickness of the GC-IPL layer was significantly decreased in the aflibercept and total group (P = .035 and P = .048, respectively).The thicknesses of the RNFL and GC-IPL decreased in patients with exudative AMD who underwent repeated anti-VEGF injections.

Trends and Challenges in Tumor Anti-Angiogenic Therapies

Excessive abnormal angiogenesis plays a pivotal role in tumor progression and is a hallmark of solid tumors. This process is driven by an imbalance between pro- and anti-angiogenic factors dominated by the tissue hypoxia-triggered overproduction of vascular endothelial growth factor (VEGF). VEGF-mediated signaling has quickly become one of the most promising anti-angiogenic therapeutic targets in oncology. Nevertheless, the clinical efficacy of this approach is severely limited in certain tumor types or shows only transient efficacy in patients. Acquired or intrinsic therapy resistance associated with anti-VEGF monotherapeutic approaches indicates the necessity of a paradigm change when targeting neoangiogenesis in solid tumors. In this context, the elaboration of the conceptual framework of “vessel normalization” might be a promising approach to increase the efficacy of anti-angiogenic therapies and the survival rates of patients. Indeed, the promotion of vessel maturation instead of regressing tumors by vaso-obliteration could result in reduced tumor hypoxia and improved drug delivery. The implementation of such anti-angiogenic strategies, however, faces several pitfalls due to the potential involvement of multiple pro-angiogenic factors and modulatory effects of the innate and adaptive immune system. Thus, effective treatments bypassing relapses associated with anti-VEGF monotherapies or breaking the intrinsic therapy resistance of solid tumors might use combination therapies or agents with a multimodal mode of action. This review enumerates some of the current approaches and possible future directions of treating solid tumors by targeting neovascularization.

Angiogenesis: Bench to Bedside, Have We Learned Anything?

End-stage ischemic cardiomyopathy patients are an ever-increasing group of coronary artery disease patients, often with no options in our current treatment armamentarium. Angiogenesis therapy pre-clinical and phase I clinical trials showed great promise, however, the benefits of single growth factor treatments have not been borne out in the larger phase II randomized trials. The complexity of angiogenesis process and the challenges in creating animal models to replicate and study this process in ischemic adult human myocardium have been major limitations to progress in this field. In addition failure to control for the powerful placebo effect in the clinical trials and inadequate methods of outcomes measures assessment have created difficult to overcome road blocks in establishing the efficacy of angiogenic strategies. Herein we review the challenges of angiogenesis research and development of treatment strategies. We also propose a structured model for further investigations of angiogenic therapies. The adherence to such a regimented approach as proposed here is, in our opinion, the only way to achieve success in angiogenesis approach development to treatment of patients with end-stage cardiac ischemia refractory to other established therapies.

Therapeutic angiogenesis by vascular endothelial growth factor supplementation for treatment of renal disease

PURPOSE OF REVIEW

Vascular endothelial growth factors (VEGFs) influence renal function through angiogenesis, with VEGF-A being the most potent inducer of vascular formation. In the normal glomerulus, tight homeostatic balance is maintained between the levels of VEGF-A isoforms produced by podocyte cells, and the VEGF receptors (VEGFRs) expressed by glomerular endothelial, mesangial, and podocyte cells. Renal disease occurs when this homeostatic balance is lost, manifesting in the abnormal autocrine and paracrine VEGF-A/VEGFR signaling, ultrastructural glomerular and tubular damage, and impaired filtration.

RECENT FINDINGS

Preclinical disease models of ischemic renal injury, including acute ischemia/reperfusion, thrombotic microangiopathy, and chronic renovascular disease, treated with exogenous VEGF supplementation demonstrated therapeutic efficacy. These results suggest a therapeutic VEGF-A paracrine effect on endothelial cells in the context of acute or chronic obstructive ischemia. Conversely, renal dysfunction in diabetic nephropathy appears to occur through an upregulated VEGF autocrine effect on podocyte cells, which is exacerbated by hyperglycemia. Therefore, VEGF supplementation therapy may be contraindicated for treatment of diabetic nephropathy, but specific results will depend on dose and on the specific site of VEGF delivery. A drug delivery system that demonstrates cell specificity for glomerular or peritubular capillaries could be employed to restore balance to VEGF-A/VEGFR2 signaling, and by doing so, prevent the progression to end-stage renal disease.

SUMMARY

The review discusses the preclinical data available for VEGF supplementation therapy in models of renal disease.

The Rabbit Corneal Pocket Assay

The rabbit corneal micropocket angiogenesis assay uses the avascular cornea as a substrate canvas to study angiogenesis in vivo. Through the use of standardized slow-release pellets, a predictable angiogenic response is generated over the course of 1-2 weeks and then quantified. Uniform slow-release pellets are prepared by mixing purified angiogenic growth factors such as basic fibroblast growth factor or vascular endothelial growth factor and a synthetic polymer to allow slow release. A micropocket is surgically created in the rabbit cornea under anesthesia and a pellet implanted. On the days later, the angiogenic response is measured and qualified using a slit lamp, as well as the concomitant vascular phenotype or inflammatory features. The results of the assay are used to assess the ability of potential therapeutic molecules to modulate angiogenesis in vivo, both when released locally or given by ocular formulations or through systemic treatment. In this chapter, the experimental details of the rabbit cornea assay and technical implementations to the original protocol are described.

Therapeutic angiogenesis for myocardial ischemia

Therapeutic angiogenesis offers promise as a novel treatment for ischemic heart disease, particularly for patients who are not candidates for current methods of revascularization. The goal of treatment is both relief of symptoms of coronary artery disease and improvement of cardiac function by increasing perfusion to the ischemic region. Protein-based therapy with cytokines including vascular endothelial growth factor and fibroblast growth factor demonstrated functionally significant angiogenesis in several animal models. However, clinical trials have yielded largely disappointing results. The attenuated angiogenic response seen in clinical trials of patients with coronary artery disease may be due to multiple factors including endothelial dysfunction, particularly in the context of advanced atherosclerotic disease and associated comorbid conditions, regimens of single agents, as well as inefficiencies of current delivery methods. Gene therapy has several advantages over protein therapy and recent advances in gene transfer techniques have improved the feasibility of this approach. The safety and tolerability of therapeutic angiogenesis by gene transfer has been demonstrated in phase I clinical trials. The utility of therapeutic angiogenesis by gene transfer as a treatment option for ischemic cardiovascular disease will be determined by adequately powered, randomized, placebo-controlled Phase II and III clinical trials. Cell-based therapies offer yet another approach to therapeutic angiogenesis. Although it is a promising therapeutic strategy, additional preclinical studies are warranted to determine the optimal cell type to be administered, as well as the optimal delivery method. It is likely the optimal treatment will involve multiple agents as angiogenesis is a complex process involving a large cascade of cytokines, as well as cells and extracellular matrix, and administration of a single factor may be insufficient. The promise of therapeutic angiogenesis as a novel treatment for no-option patients should be approached with cautious optimism as the field progresses.

[VEGF promotes the proliferation of bone marrow derived mesenchymal stem cells through ERK1/2 signal pathway]

In order to explore the effect of VEGF on mesenchymal stem cell (MSC) proliferation and its possible signal transduction mechanism, MSC culture was performed with the classical bone marrow adhering method; characteristics of passage 3 rat MSC (P3MSC) was identified through multi-differentiation and surface marker assay (CD34, CD45, CD90, CD29); P3MSC were treated with 20 ng/ml VEGF, and the effect of VEGF on the MSC proliferation was measured during 12, 36 and 72 hours by MTT assay. Subsequently, P3MSC were treated with extracellular-signal regulated kinase (ERK1/2) inhibitor PD98059 (50 µmol/L) or p38 mitogen-activated protein kinase (p38MAPK) inhibitor SB203580 (30 µmol/L) for 30 minutes, the culture medium was replaced with new medium including 20 ng/ml VEGF. After 72 hours, the effect of PD98059 or SB203580 on MSC proliferation mediated by VEGF was measured by MTT assay. The result showed that the cultured MSC expressed PDGFR-α, PDGFR-β and NRP1, but did not express VEGF-R (Flk1 and Flt1). The MSC had the multi-differentiation ability and displayed the characteristics of CD90+ (96.7%), CD29+ (94.6%), CD34- (0.79%) and CD45- (0.84%). The MSC proliferation rate increased gradually with prolonging of the functioning time of 20 ng/ml VEGF, and MSC proliferation rate may reach to maximum value after treating with 20 ng/ml VEGF for 72 hours. The effect of VEGF on MSC proliferation was found to be abolished, even was under level of control group after treating with PD98059 or SB203580 for 30 minutes. Furthermore, the inhibitory effect of PD98059 on MSC proliferation was obviously higher than that of SB203580. It is concluded that the VEGF can promote MSC proliferation, and its possible mechanism may relate to ERK1/2 pathway.

Preparation and characterization of collagen microspheres for sustained release of VEGF

In this study, we prepared injectable collagen microspheres for the sustained delivery of recombinant human vascular endothelial growth factor (rhVEGF) for tissue engineering. Collagen solution was formed into microspheres under a water-in-oil emulsion condition, followed by crosslinking with water-soluble carbodiimide. Various sizes of collagen microspheres in the range of 1-30 mum diameters could be obtained by controlling the surfactant concentration and rotating speed of the emulsified mixture. Particle size proportionally decreased with increasing the rotating speed (1.8 mum per 100 rpm increase in the range of 300-1,200 rpm) and surfactant concentration (3.1 mum per 0.1% increase in the range of 0.1-0.5%). The collagen microspheres showed a slight positive charge of 8.86 and 3.15 mV in phosphate-buffered saline and culture medium, respectively. Release study showed the sustained release of rhVEGF for 4 weeks. Released rhVEGF was able to induce capillary formation of human umbilical vein endothelial cells, indicating the maintenance of rhVEGF bioactivity after release. In conclusion, the results suggest that the collagen microspheres have potential for sustained release of rhVEGF.

Induced endothelial differentiation of cells from a murine embryonic mesenchymal cell line C3H/10T1/2 by angiogenic factors in vitro

A murine embryonic mesenchymal cell line C3H/10T1/2 possesses the potential to differentiate into multiple cell phenotypes and has been recognized as multipotent mesenchymal stem cells, but no in vitro model of its endothelial differentiation has been established and the effect of angiogenic factors on the differentiation is unknown. The aim of the present study was to evaluate the role of angiogenic factors in inducing endothelial differentiation of C3H/10T1/2 cells in vitro. C3H/10T1/2 cells were treated with angiogenic factors, VEGF (10 ng/mL) and bFGF (5 ng/mL). At specified time points, cells were subjected to morphological study, immunofluorescence staining, RT-PCR, LDL-uptake tests and 3-D culture for the examination of the structural and functional characteristics of endothelial cells. Classic cobblestone-like growth pattern appeared at 6 day of the induced differentiation. Immunofluorescence staining and RT-PCR analyses revealed that the induced cells exhibited endothelial cell-specific markers such as CD31, von Willebrand factor, Flk1, Flt1, VE-cadherin, Tie2, EphrinB2 and Vezf1 at 9 day. The induced C3H/10T1/2 cells exhibited functional characteristics of the mature endothelial phenotype, such as uptake of acetylated low-density lipoproteins (Ac-LDL) and formation of capillary-like structures in three-dimensional culture. At 9 day, Weibel-Palade bodies were observed under a transmission electron microscope. This study demonstrates, for the first time, endothelial differentiation of C3H/10T1/2 cells induced by angiogenic factors, VEGF and bFGF, and confirms the multipotential differentiation ability. This in vitro model is useful for investigating the molecular events in endothelial differentiation of mesenchymal stem cells.

Vascular endothelial growth factor prevents G93A-SOD1-induced motor neuron degeneration

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disorder characterized by selective loss of motor neurons (MNs). Twenty percent of familial ALS cases are associated with mutations in Cu(2+)/Zn(2+) superoxide dismutase (SOD1). To specifically understand the cellular mechanisms underlying mutant SOD1 toxicity, we have established an in vitro model of ALS using rat primary MN cultures transfected with an adenoviral vector encoding a mutant SOD1, G93A-SOD1. Transfected cells undergo axonal degeneration and alterations in biochemical responses characteristic of cell death such as activation of caspase-3. Vascular endothelial growth factor (VEGF) is an angiogenic and neuroprotective growth factor that can increase axonal outgrowth, block neuronal apoptosis, and promote neurogenesis. Decreased VEGF gene expression in mice results in a phenotype similar to that seen in patients with ALS, thus linking loss of VEGF to the pathogenesis of MN degeneration. Decreased neurotrophic signals prior to and during disease progression may increase MN susceptibility to mutant SOD1-induced toxicity. In this study, we demonstrate a decrease in VEGF and VEGFR2 levels in the spinal cord of G93A-SOD1 ALS mice. Furthermore, in isolated MN cultures, VEGF alleviates the effects of G93A-SOD1 toxicity and neuroprotection involves phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling. Overall, these studies validate the usefulness of VEGF as a potential therapeutic factor for the treatment of ALS and give valuable insight into the responsible signaling pathways and mechanisms involved.

[BMP-4 and VEGF promote development of hematopoietic stem cells during the embryoid body formation from embryonic stem cells]

The objective of this study was to explore the effects of BMP-4 and VEGF on the development of primary hematopoietic stem cells during the differentiation of embryonic stem cells (ESCs) into embryoid body (EB). Murine E14 ESCs were seeded into semisolid methylcellulose-based medium for EB formation. According to added or not cytokines, experiments were divided into: (1) group of spontaneous differentiation without cytokine as control; (2) group of BMP-4 in different concentrations (0, 5, 15, 25 and 50 ng/ml); (3) group of BMP-4 combined with VEGF; (4) group of VEGF alone. EBs were collected on days 3, 6, 9, 12, 15, and the proportion of Flk-1(+) cells were assayed by flow cytometry. The results showed that in the different BMP-4 concentration groups, the proportions of Flk-1(+) cells were significantly different, and it reached the peak values in 25 ng/ml BMP-4 group as 6.51 +/- 1.02% at day 3 and 7.70 +/- 1.12% at day 6 respectively, which were statistically higher than those in control group without-BMP-4 and in 5 ng/ml BMP-4 group (p < 0.05). When BMP-4 was used in combination with VEGF, Flk-1(+) cells went to peak proportion value at day 9 as 27.53 +/- 8.14%, which was statistically higher than that in spontaneous differentiation group as 8.77 +/- 2.35% (p < 0.05) and VEGF treatment group as 11.21 +/- 2.23% (p < 0.05). It is concluded that BMP-4 in combination with VEGF can promote Flk-1(+) cells genesis during EB formation in vitro, which provides experimental evidence for researches on directed differentiation of ESCs into hematopoietic stem cells simulating the microenvironment in vivo.

Growth factor-induced therapeutic neovascularization for ischaemic vascular disease: time for a re-evaluation?

PURPOSE OF REVIEW

Therapeutic angiogenesis and arteriogenesis represent an alternative treatment modality for patients with advanced ischaemic coronary or peripheral artery occlusive disease, who are unsuitable for standard revascularization procedures.

RECENT DEVELOPMENTS

Proof-of-concept evidence for therapeutic growth factor, both gene and protein-mediated neovascularization was provided in animal models of chronic myocardial and hindlimb ischaemia. Early human, phase I, trials utilizing the prototypical growth factor families, vascular endothelial growth factor and fibroblast growth factor, documented safety and suggested improvements in anginal symptoms and functional status. Large, randomized, placebo-controlled phase II/III clinical trials have, however, yielded variable results as such studies have suffered from significant limitations in therapeutic approach or design, which limits the ability to draw firm conclusions.

SUMMARY

Future trials must incorporate robust delivery strategies and address issues of study design including proper patient selection. Laboratory-based refinements in therapy, including a focus on the promotion of arteriogenesis and the modification of patient 'endotheliopathy', will all further enhance the potential of therapeutic neovascularization strategies.

Antisense to cyclin D1 inhibits vascular endothelial growth factor-stimulated growth of vascular endothelial cells: implication of tumor vascularization

PURPOSE

Our aim was to determine the effects of cyclin D1 inhibition on tumor-associated neovascularization and endothelial cell growth.

EXPERIMENTAL DESIGN

We have generated adenovirus system for antisense to cyclin D1 (AS CyD1) and evaluated in vitro and in vivo effects. Small interfering RNA against cyclin D1 was also used to analyze cyclin D1 inhibition-associated vascular endothelial growth factor (VEGF) regulation.

RESULTS

The xenografts treated with adenoviral AS CyD1 showed less vessel density and displayed smaller tumor size in colon cancer cell lines HCT116 and DLD1. In vitro studies indicated that AS CyD1 decreased VEGF protein expression in DLD1 but not in HCT116. Cyclin D1 small interfering RNA caused a decrease in VEGF expression at protein and RNA levels in DLD1. A modest decrease was noted in the VEGF promoter activity, with inactivation of the STAT3 transcription factor through dephosphorylation. On the hand, the cyclin D1 inhibition plus STAT3 inhibitor markedly decreased VEGF expression in HCT116, although VEGF did not change by the STAT3 inhibitor alone. In cultures of human umbilical vein endothelial cells (HUVEC), VEGF augmented cyclin D1 expression and cell growth. AS CyD1 significantly inhibited HUVEC growth even in the presence of VEGF. AS CyD1 also significantly suppressed in vitro tube formation in VEGF-treated HUVEC and in vivo macroaneurysm formation in VEGF-treated Matrigel plug.

CONCLUSIONS

Our results suggest that cyclin D1 may play a role in the maintenance of VEGF expression and that AS CyD1 could be potentially useful for targeting both cancer cells and their microenvironment of tumor vessels.

Differential regulation of thrombospondin-1 expression and antiangiogenesis of ECV304 cells by trichostatin A and helixor A

Trichostatin A and helixor A increased thrombospondin-1 expression by ECV304 cells at both mRNA and protein levels by transcriptional activation through the enhancement of tsp-1 promoter activity. The induction of thrombospondin-1 by these agents potently reduced ECV 304 cell migration and capillary-like tube formation on Matrigel; these findings were confirmed by the neutralization of thrombospondin-1 using a specific antibody. In the presence of exogenous vascular endothelial growth factor, however, these agents had a different effect on the vascular endothelial growth factor-induced tube formation; trichostatin A remarkably inhibited tube formation regardless of the presence of exogenous vascular endothelial growth factor, whereas helixor A reduced it to 70-80% of the control level. Interestingly, when the helixor A-generated conditioned media were concentrated three-fold and the endogenous vascular endothelial growth factor was removed, tube formation was remarkably inhibited compared with the effect of three-fold concentrated conditioned media that had endogenous vascular endothelial growth factor. Additionally, in media with endogenous vascular endothelial growth factor that were concentrated five-fold, tube formation was markedly blocked regardless of the presence of exogenous or endogenous vascular endothelial growth factor. Thus, our results indicate that trichostatin A-induced or helixor A-induced antiangiogenesis is mediated by both agents; increased, absolute and relative levels of thrombospondin-1 to the vascular endothelial growth factor level are critical in angiogenesis.

Fibrin-embedded administration of VEGF plasmid enhances skin flap survival

The aim of the present study was to experimentally evaluate whether topical fibrin-mediated administration of a vascular endothelial growth factor (VEGF)-A plasmid to the wound bed can protect skin flaps from necrosis. A plasmid expression vector containing the VEGF-A cDNA was constructed. The plasmid was then administered to the wound bed of rat abdominal skin flaps in a fibrin sealant. The percentage of viable, ischemic and necrotic tissue was assessed postoperatively as a baseline and after 3 and 7 days using digital surface area morphometry. Laser Doppler imaging of the flaps and VEGF-A Western blot analysis of flap tissue were performed to assess angiogenesis and VEGF-A tissue levels. Flaps treated with VEGF plasmids in the presence of uptake enhancing Lipofectamine transfection reagent increased flap survival 7 days postoperatively significantly associated with markedly elevated tissue perfusion and enhanced tissue VEGF-A protein expression. Our results indicate that topical fibrin-mediated administration of a VEGF-A plasmid may serve as an alternative to previous strategies in treating ischemic skin flaps. The suggested therapeutic approach is easily applicable and inexpensive in preparation. Thus, this protocol may also enhance wound healing in posttrauma skin lacerations or in skin grafts.

Endothelial progenitor cells contribute to accelerated liver regeneration

Two classes of circulating endothelial cells (CECs) have been identified and are distinguished by the expression of the stem cell markers CD117 or CD133 together with endothelial-specific antigens. Stem cell marker-positive CECs originate from bone marrow and have been designated as circulating endothelial progenitors (CEPs). We have demonstrated that exogenous vascular endothelial growth factor (VEGF) effectively mobilizes CEP cells. Furthermore, it has been demonstrated that VEGF regulates liver regeneration after partial hepatectomy. Although local endothelial cells can regulate tissue mass during liver regeneration, the contribution of CEPs to this process is unknown. We discovered loss of CD117 and CD133 from murine CEP cells and that both markers underestimated the number of bone marrow-derived CEP cells. We therefore used wild type and green fluorescent protein (GFP)-bone marrow transplanted into wild-type mice and performed 70% hepatectomies. Furthermore, we found that treatment with exogenous VEGF accelerated liver regeneration after 70% hepatectomy, whereas immunohistochemical analysis showed a 7-fold increase in the incorporation of CEP cells into liver vasculature. These results suggest that CEP cells play a role in regulating liver regeneration and that VEGF treatment can mobilize CEP cells to accelerate this process.

[Synergism between Ang-2 and VEGF and its application of anti-angiogenesis in tumor therapy - review]

Tumor angiogenesis is a complicated process in which VEGF and the members of Ang family have been proposed to play an important role. Ang family is the only vascular growth factor family including activators and inhibitors. They can all bind with specific tyrosine kinase receptor Tie-2 and participate in angiogenesis. Vascular endothelial growth factor (VEGF) is secreted by tumor cells and coordinates with Ang to promote angiogenesis. Further research on the structure and functional mechanism of VEGF and Ang will contribute to develop a new type of antiangiogenesis medicine, which might have good perspect in clinical practice. In this paper, the structure and action mechanism of Ang family and its receptor Tie-2, the application of Ang family and Tie in tumor therapy, and the synergic mechanism between Ang and VEGF were summarized.

Rebuilding the coronary vasculature: hedgehog as a new candidate for pharmacologic revascularization

Myocardial infarction and ischemic heart disease are among the most common causes of morbidity and mortality in the industrial world. Surgical and percutaneous intravascular approaches are commonly used to treat these diseases. Regrettably, a significant number of patients are either ineligible or demonstrate suboptimal responses to these therapies. In an attempt to provide such patients improved therapeutic options, much effort has been spent developing noninvasive approaches to restore coronary vascular perfusion. One such strategy, termed therapeutic revascularization or angiogenesis, involves administration of proangiogenic factors, which improve coronary perfusion by promoting growth of the coronary vasculature. Thus far, two potential proangiogenic factors have been intensively examined, fibroblast growth factor and vascular endothelial growth factor. Unfortunately, despite their apparent efficacy in animal models, neither factor has performed adequately in the clinic to date. Within the past year a new factor, hedgehog, has been shown to effectively promote the growth of the coronary vasculature and thus has been proposed as a novel candidate for therapeutic revascularization. In this review, we discuss the discovery of the hedgehog pathway as an essential regulator of the development of the coronary vasculature, as an inducer of adult coronary vascular growth, and as a therapeutic in the treatment of ischemic heart disease.

[The effects of vascular endothelial growth factor on survival of reverse flow axial skin flaps]

OBJECTIVE

To research the effects of vascular endothelial growth factor (VEGF) on the survival of reverse flow axial skin flaps.

METHODS

A 8 cm x 2 cm full thickness transverse dorsal flap based on right deep circumflex iliac artery was elevated in 20 Sprague-Dawley rats, which length crossing midline was 4.0 cm. The rats were randomized into two groups:experimental group n = 10), subcutaneous VEGF injections into the flap (200 ng, 200 microl) after flap elevation; control group (n = 10), subcutaneous saline injections into the flap (200 microl) after flap elevation. The flap was immediately sutured to its recipient beds then the injection was executed. Seven days after operation, the survival area of flaps and density of vessels were observed and measured, meanwhile its histological representation of the flaps was examined.

RESULTS

After 7 days of recovery, the mean survival area of flaps was 15.55+/-0.27 cm2 in experimental group and 13.42+/-0.57 cm2 in control group. The difference was significant between experimental group and control group (P<0.01). The mean vessel density of flaps was 21.00+/-3.16 in control group and 34.40+/-3.75 in experimental group. The difference was significant between experimental group and control group (P < 0.01). Histological analysis demonstrated that a qualitatively greater amount of granulation tissue, regular collagen fiber and a lot of fibrillated cells were observed in experimental group. Erythrocytes were leaked out from vessels, and inflammatory cells were observed around in control group.

CONCLUSION

In early survival of flaps, the VEGF can improve the survival of a reverse flow axial skin flap through improving angiogenesis and increasing the perfusion of vessel. It is an effective method of improving the survival of reverse flow axial skin flaps that VEGF is fully injected in subcutaneous flaps by single, when flaps are elevated.

Synergistic effect of combined intramyocardial CD34+ cells and VEGF2 gene therapy after MI

Previous studies have shown that local angiogenic gene therapy acts, in part, by recruiting endothelial progenitor cells (EPCs) to ischemic tissue. Recent data indicate that patients with the most severe vascular disease may have insufficient or deficient EPCs and the poorest response to angiogenic therapy. Accordingly, we hypothesized that combining human CD34(+) cell implantation with local vascular endothelial growth factor 2 (phVEGF2) gene therapy might overcome these deficiencies. The addition of VEGF2 to EPC cultures resulted in significant and dose-dependent decreases in EPC apoptosis. Phosphorylated Akt (p-Akt) was increased in VEGF2-treated EPCs. In vivo, myocardial infarction (MI) was induced by ligation of the left anterior descending coronary artery in 34 immunodeficient rats. The animals were then randomized to one of four treatment groups: cell therapy alone with human CD34(+) cells; VEGF2 gene therapy alone; combination therapy with CD34(+) cells plus phVEGF2; or CD34(-) cells and 50 microg empty plasmid. Four weeks after MI, animals treated with combination therapy showed improved fractional shortening, increased capillary density, and reduced infarct size compared with the other three groups. Combination therapy was also associated with an increased number of circulating EPCs 1 week after MI. Combined subtherapeutic doses of cell and gene therapy result in a significant therapeutic effect compared to monotherapy. This approach may overcome therapeutic failures (e.g. inability of certain patients to mobilize sufficient EPCs) and may also offer safety advantages by allowing lower dosing strategies.

Expression of the non-glycosylated kringle domain of tissue type plasminogen activator in Pichia and its anti-endothelial cell activity

The two-kringle domain of tissue-type plasminogen activator (TK1-2) has been identified as a potent angiogenesis inhibitor by suppressing endothelial cell proliferation, in vivo angiogenesis, and in vivo tumor growth. Escherichia coli-derived, non-glycosylated TK1-2 more potently inhibits in vivo tumor growth, whereas Pichia expression system is more efficient for producing TK1-2 as a soluble form, albeit accompanying N-glycosylation. Therefore, in order to avoid immune reactivity and improve in vivo efficacy, we expressed the non-glycosylated form of TK1-2 in Pichia pastoris and evaluated its activity in vitro. When TK1-2 was mutated at either Asn(117) or Asn(184) by replacing with Gln, the mutated proteins produced the glycosylated form in Pichia, of which sugar moiety could be deleted by endoglycosidase H treatment. When both sites were replaced by Gln, the resulting mutant produced a non-glycosylated protein, NQ-TK1-2. Secreted NQ-TK1-2 was purified from the culture broth by sequential ion exchange chromatography using SP-sepharose, Q-spin, and UNO-S1 column. The purified NQ-TK1-2 migrated as a single protein band of approximately 20 kDa in SDS-PAGE and its mass spectrum showed one major peak of 19,950.71 Da, which is smaller than those of two glycosylated forms of wild type TK1-2. Functionally, the purified NQ-TK1-2 inhibited endothelial cell proliferation and migration stimulated by bFGF and VEGF, respectively. Therefore, the results suggest that non-glycosylated TK1-2 useful for the treatment of cancer can be efficiently produced in Pichia, with retaining its activity.

Effect of heparin affin regulatory peptide on the expression of vascular endothelial growth factor receptors in endothelial cells

BACKGROUND

Heparin affin regulatory peptide (HARP) is an 18-kDa secreted protein that has been implicated in tumor growth and angiogenesis, although the mechanisms involved remain largely unknown. In the present work, the effect of human recombinant HARP on the expression of the vascular endothelial growth factor (VEGF) receptors KDR, Flt-1 and neuropilin-1 was studied in cultured human umbilical vein endothelial cells (HUVEC).

MATERIALS AND METHODS

The mRNA and protein levels of VEGF receptors were estimated by semi-quantitative RT-PCR and Western blot, respectively. Cell proliferation and migration were measured by MTT, direct counting of the cells and modified Boyden chamber assays.

RESULTS

HARP decreased the expression of KDR but increased the expression of Flt-1 and neuropilin-1 at both the mRNA and protein level. The effect reached a maximum 4 h after the addition of HARP into the cell culture medium and was reversed at later time-points. When HARP was added to the culture medium 4 h before the addition of VEGF165, it inhibited VEGF165-induced proliferation and migration of HUVEC.

CONCLUSION

These data suggest that HARP affects the expression of VEGF receptors and inhibits VEGF165-induced activation of HUVEC.

Molecular Profile and Proliferative Responses of Rat Lymphatic Endothelial Cells in Culture

BACKGROUND

Lymphangiogenesis plays an important role in metastasis of many solid tumors. To study lymphangiogenesis under controlled conditions, an in vitro model is needed. The goal of this work was to establish such an in vitro model by determining a molecular profile of rat mesenteric lymphatic endothelial cells (RMLEC) and characterizing their proliferative responses to angiogenic and lymphangiogenic factors, such as vascular endothelial growth factor A and C (VEGF-A and VEGF-C).

METHODS AND RESULTS

RMLEC strongly expressed most lymphatic-specific markers, including Prox-1, LYVE-1, and VEGFR-3. Proliferation of RMLEC was serum and heparin dependent. In the presence of low (2%) serum concentration, exogenously added VEGF-A and VEGFC stimulated RMLEC in a linear and dose-dependent manner. This effect was abrogated by anti-VEGF-A and VEGF-C antibodies, as well as by soluble Tie-2 and Flt-4 fusion proteins. Abrogation was reversed by VEGF-A, suggesting that this factor as an important regulator of lymphangiogenesis.

CONCLUSIONS

Cultured RMLEC preserved a molecular profile consistent with the phenotype of lymphatic endothelium in vivo and respond to either VEGF-A or VEGF-C factors. VEGFA was able to rescue RMLEC proliferation inhibited by a neutralizing VEGF-C antibody or soluble Tie-2 fusion protein. These results support the existence of cross-talk among angiogenic and lymphangiogenic factors. This work established experimental conditions that allow in vitro modeling of lymphatic endothelial responses to lymphangiogenic regulators. Preliminary results using this model suggest that VEGF-A, VEGF-C, and angiopoietins work in concert to promote lymphangiogenesis in vivo.

Essential role of nitric oxide in VEGF-induced, asthma-like angiogenic, inflammatory, mucus, and physiologic responses in the lung

VEGF, nitric oxide (NO), inflammation, and vascular- and extravascular remodeling coexist in asthma and other disorders. In these responses, VEGF regulates angiogenesis. VEGF also induces inflammation and remodeling. The mechanisms of the latter responses have not been defined, however. We hypothesized that VEGF-induces extravascular tissue responses via NO-dependent mechanisms. To evaluate this hypothesis, we compared the effects of transgenic VEGF165 in lungs from normal mice, mice treated with pan-NO synthase (NOS) or endothelial NOS (eNOS) inhibitors, and mice with null mutations of inducible NOS (iNOS) or eNOS. These studies demonstrate that VEGF selectively stimulates eNOS and iNOS. They also demonstrate that VEGF induces pulmonary alterations via NO-dependent and -independent mechanisms with angiogenesis, edema, mucus metaplasia, airway hyperresponsiveness, lymphocyte accumulation, dendritic cell hyperplasia and S-nitrosoglutathione reductase stimulation being NO-dependent and dendritic cell activation being NO-independent. Furthermore, they demonstrate that eNOS and iNOS both contribute to these responses. NO/NOS-based interventions may be therapeutic in VEGF-driven inflammation and remodeling.

Tyrosine phosphorylation and the small GTPase rac cross-talk in regulation of endothelial barrier function

Endothelial barrier function depends on the integrity of intercellular adherens junctions controlled by the association of VE-cadherin/catenin complex with cortical actin filaments. Both tyrosine phosphorylation/dephosphorylation of junctional proteins and actin reorganization mediated by rho-GTPases regulate barrier function but the relationship between these regulatory mechanisms is unclear. Here we studied the effects of factors increasing protein tyrosine phosphorylation, pervanadate (PV) and VEGF, on distribution of VE-cadherin, F-actin polymerization and transendothelial electrical resistance (TER) in human umbilical vein endothelial cells (HUVECs). Changes in protein tyrosine phosphorylation of cytoplasmic and junctional proteins, as well as the activity of rho-GTPase racl, were also measured. We report for the first time that PV and VEGF induced a rapid transient increase in endothelial barrier function accompanied by rac1 activation, a differentiated tyrosine phosphorylation of the VE-cadherin/catenin complex, recruitment of actin filament to cell junctions and ruffle formation. A sustained decrease in endothelial barrier function was observed at later times of PV and VEGF treatment. Expression of dominant negative rac1, N17rac1 abolished the barrier-enhancing effects of PV and VEGF, while the sustained decrease in barrier function was unaffected. These observations bring into focus early short-term effects of protein tyrosine phosphorylation in cells, often overshadowed by more pronounced and long-lasting later effects and may play an important role in the regulation of endothelial barrier function.

VEGF receptors on PC12 cells mediate transient activation of ERK1/2 and Akt: comparison of nerve growth factor and vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) and endostatin are angiogenic and anti-angiogenic molecules, respectively, that have been implicated in neurogenesis and neuronal survival. Using alkaline phosphatase fusion proteins, we show that the PC12 neuronal cell line contains cell membrane receptors for VEGF but not for endostatin and the collagen XV endostatin homologue. Immunocytochemistry confirmed that proliferating and differentiated PC12 cells express VEGF receptors 1, 2 and neuropilin-1. While no functional effects of VEGF on PC12 cell proliferation and differentiation could be observed, a slight VEGF-induced reduction of caspase-3 activity in differentiated apoptotic PC12 cells was paralleled by transient activation of ERK1/2 and Akt. In direct comparison, nerve growth factor proved to be a strikingly more potent neuroprotective agent than VEGF.

The angiosuppressive effects of 20(R)- ginsenoside Rg3

Aberrant angiogenesis is an essential step for the progression of solid tumors. Thus anti-angiogenic therapy is one of the most promising approaches to control tumor growth. In this study, we examined the ability of 20(R)-ginsenoside Rg3 (Rg3), one of the active compounds present in ginseng root, to interfere with the various steps of angiogenesis. Rg3 was found to inhibit the proliferation of human umbilical vein endothelial cells (HUVEC) with an IC50 of 10 nM in Trypan blue exclusion assay. Rg3 (1-10(3) nM) also dose dependently suppressed the capillary tube formation of HUVEC on the Matrigel in the presence or absence of 20 ng/ml vascular endothelial growth factor (VEGF). The VEGF-induced chemoinvasion of HUVEC and ex vivo microvascular sprouting in rat aortic ring assay were both significantly attenuated by Rg3. In addition, Rg3 (150 and 600 nM) remarkably abolished the basic fibroblast growth factor (bFGF)-induced angiogenesis in an in vivo Matrigel plug assay. The Matrix metalloproteinases (MMPs), such as MMP-2 and MMP-9, which play an important role in the degradation of basement membrane in angiogenesis and tumor metastasis present in the culture supernatant of Rg3-treated aortic ring culture were found to decrease in their gelatinolytic activities. Taken together, these data underpin the anti-tumor property of Rg3 through its angiosuppressive activity.

[Comparison of effects of flap delay and vascular endothelial growth factor on the viability of the rat dorsal flap]

OBJECTIVE

To compare the effects of flap delay and vascular endothelial growth factor (VEGF) on the viability of the rat dorsal flap.

METHODS

Thirty rats were divided into 3 groups: saline group, flap delay group and VEGF group. The rats in flap delay group underwent flap delay by keeping bipedicle untouched, and the cranial pedicle was cut 7 days later. The rats in VEGF group were given VEGF solution locally when the flaps were elevated in the operation. The rats in saline group were given saline solution in the same way. Five days after the single pedicle flaps were performed, the flap survival rate was measured. The flap tissues were collected to measure and analyze the microvascular density, diameter and sectional area by immunochemical method.

RESULTS

The flap survival rate of flap delay group was similar to that of VEGF group and there is no statistically significant difference (P>0.05). The vascular diameter of flap delay group was much larger than that of saline group and VEGF group, showing statistically significant difference (P<0.05). The vascular density of VEGF group was much higher than that of saline group and flap delay group, showing statistically significant difference (P<0.05). The vascular sectional area of flap delay group was similar to that of VEGF group (P>0.05).

CONCLUSION

The change in the flap after flap delay is manifested as obvious dilatation of microvessels, while the change in the flap after the injection of VEGF is manifested as obvious vascular proliferation. Both flap delay and VEGF can increase the vascular sectional area and the viability of the flap, but the mechanism is different.

Angiogenesis--a new target for future therapy

Development of blood vessels from in situ differentiating endothelial cells (EC) is called vasculogenesis, whereas sprouting of new blood vessels from the pre-existing ones is termed angiogenesis or neovascularisation. Angiogenesis, the growth of new blood vessels, is essential during tissue repair, foetal development, and female reproductive cycle. In contrast, uncontrolled angiogenesis promotes tumor and retinopathies, while inadequate angiogenesis can lead to coronary artery disease. A balance between pro-angiogenic and anti-angiogenic growth factors and cytokines tightly controls angiogenesis. With the identification of several proangiogenic molecules such as the vascular endothelial cell growth factor (VEGF), the fibroblast growth factors (FGFs), and the angiopoietins, and the recent description of specific inhibitors of angiogenesis such as platelet factor-4, angiostatin, endostatin, and vasostatin, it is recognized that therapeutic interference with vasculature formation offers a tool for clinical applications in various pathologies. Inhibition of angiogenesis can prevent diseases such as cancer, diabetic nephropathy, arthritis, psoriasis, whereas stimulation of angiogenesis is beneficial in the treatment of coronary artery disease (CAD), cardiac failure, tissue injury, etc. One of the most specific and critical regulators of angiogenesis is vascular endothelial growth factor (VEGF), which regulates endothelial proliferation, permeability, and survival. Substantial evidence also implicates VEGF as an angiogenic mediator in tumors and intraocular neovascular syndromes, and numerous clinical trials are presently testing the hypothesis that inhibition of VEGF may have therapeutic value.

Electrochemical High-Content Screening of Nitric Oxide Release from Endothelial Cells

Release of nitric oxide (NO) is of high importance for regulating endothelial cell functions during vasodilatation, vascular remodeling, and angiogenesis. Thus, a direct and reliable real-time method for NO detection that takes into account time-dependent variations of the NO concentration in the complex reaction within the diffusion zone above the cells is vital for obtaining information about the role of NO in intracellular endothelial signal transduction and its impact on the surrounding cells. In this study, the time course of vascular endothelial growth factor E (VEGF-E) stimulated NO release from transformed human umbilical vein endothelial cells (T-HUVEC) was investigated by means of metalloporphyrin-based NO sensors employed in an electrochemical robotic system. The NO sensor was obtained by electrochemically induced deposition of Ni(II) tetrakis(p-nitrophenylporphyrin) on a 50-microm diameter platinum disk electrode which was integrated, together with a 25-microm diameter platinum disk, in a double-barrel electrode arrangement. The second electrode was used as a guidance sensor for the automatic and highly reproducible positioning of the NO sensor at a known distance from a layer of adherently growing cells by using z-approach curves in the negative feedback mode of scanning electrochemical microscopy (SECM). The electrochemical robotic system allows the fully automated detection of NO with high sensitivity and selectivity to be performed in real time within 96-well microtiter plates. A functional cell assay was established to allow the standardized detection of NO released upon stimulation from T-HUVEC with a sensor positioned at a known distance above the endothelial cells. The overall system was evaluated by automatic detection of NO release from T-HUVEC upon stimulation with VEGF-E after incubation with a variety of drugs that are known to act on different sites in the complex signal-transduction pathway that finally invokes NO release.

Emerging new drugs for wound repair

Every year, millions of people experience burns, suffer from nonhealing wounds, or have acute wounds that become complicated by infection, dehiscence or problematic scarring. Effective wound treatment requires carefully considered interventions often requiring multiple clinic or hospital visits. The resulting costs of wound care are staggering, and more efficacious and cost-effective therapies are needed to decrease this burden. Unfortunately, the expenses and difficulties encountered in performing clinical trials have led to a relatively slow growth of new treatment options for the wound management. Research efforts attempting to examine wound pathophysiology have been hampered by the lack of an adequate chronic wound healing model, and the complexity of the wound healing cascade has limited attempts at pharmacological modification. As such, currently available wound healing therapies are only partially effective. Therefore, many new therapies are emerging that target various aspects of wound repair and the promise of new therapeutic interventions is on the immediate horizon.

Uncoupling of vascular endothelial growth factor with nitric oxide as a mechanism for diabetic vasculopathy

The role of VEGF in vascular disease is complicated. Vascular endothelial growth factor (VEGF) expression can be deleterious in diabetic vasculopathy, especially in kidney and retina. In contrast, VEGF seems to be renoprotective in nondiabetic renal disease. VEGF exerts it biologic effects in association with nitric oxide (NO), yet it is known that NO bioavailability is reduced in diabetes. Thus, it was hypothesized that this diverse biologic effect of VEGF on diabetic vasculopathy is due to uncoupling of VEGF with NO. VEGF stimulated NO production in a dose-dependent manner in bovine aortic endothelial cells (BAEC), and this was inhibited by either high glucose or Nomega-nitro-l-arginine methyl ester (L-NAME) treatment. Endothelial NO synthase phosphorylation by VEGF was also inhibited by high glucose. It is interesting that both high glucose and L-NAME enhanced the proliferative response of endothelial cells, which was prevented by an NO donor. Furthermore, high glucose as well as L-NAME stimulated VEGF and kinase-insert domain receptor (KDR) (VEGF receptor 2) mRNA expression in BAEC. These data suggest that the uncoupling of VEGF with NO enhances endothelial cell proliferation via the KDR pathway. Compatible with these findings, a KDR antagonist blocked this response. In addition, a VEGF mutant, which binds only KDR, induced extracellular signal-regulated kinase (ERK) activation, and inhibition of ERK completely blocked endothelial cell proliferation under this condition, suggesting a role of the KDR-ERK1/2 pathway on endothelial cell proliferation. In conclusion, high glucose causes an uncoupling of VEGF with NO, which enhances endothelial cell proliferation via activation of the KDR-ERK1/2 pathway. These results may provide new insights into the understanding of the mechanism of diabetic vascular disease.

Inhibition of human leukemia xenograft in nude mice by adenovirus-mediated tissue inhibitor of metalloproteinase-3

Considerable studies have demonstrated the pivotal roles of matrix metalloproteinases (MMPs) in leukemia dissemination and extramedullary infiltration. Tissue inhibitors of matrix metalloproteinases (TIMPs) are multifunctional proteins with MMPs inhibitory effects. However, little is known about the application of TIMPs in the treatment of leukemia. Here, we investigated the effects of TIMP-3 overexpression via adenoviral gene delivery on the in vitro growth and invasiveness of leukemic cells and the in vivo progress of K562-derived xenografts in nude mice. The in vitro invasiveness of K562 cells was markedly impaired by AdTIMP-3 infection. Moreover, TIMP-3 significantly inhibited K562-derived angiogenic factors-induced proliferation, migration and bFGF-induced tube formation of endothelial cells (ECs) in vitro, and reduced VEGF-induced gelatinases expression and activation in ECs. Although TIMP-3 overexpression had no direct effect on the growth of K562 cells in vitro, repeated intratumoral injection of AdTIMP-3 significantly inhibited the growth of K562 xenografts in nude mice. Furthermore, lower microvessel density, less vessel maturity and increased apoptosis were observed in AdTIMP-3-treated K562 xenografts, suggesting the importance of antiangiogenic action of TIMP-3. These data demonstrated the potential of applying AdTIMP-3 as an effective antiangiogenic adjuvant in the treatment of leukemia progression.

Fluid shear stress modulates cell migration induced by sphingosine 1-phosphate and vascular endothelial growth factor

The rational design of drug delivery systems requires the ability to predict the environment-specific responses of target cells to the delivered drug. Here we describe the in vitro effects of fluid shear stress, vascular endothelial growth factor (VEGF), and sphingosine 1-phosphate (S1P) on the migration of human umbilical vein endothelial cells (HUVEC). Endothelial cell migration into a scrape wound was enhanced in S1P- or VEGF-stimulated HUVEC by the addition of fluid shear stress. In both cases, scrape wound closure rates were near a maximal value that was not exceeded when cells were exposed to all three factors. We also found that cell migration into a scrape wound due to S1P stimulation was correlated with the S1P1 mRNA concentration, in systems where cell migration was not already near maximal. The present work represents our initial steps toward predicting cell migration based upon the activation state of the receptors and enzymes involved in the chemokinetic response. These results also illustrate the importance of context-dependent analysis of cell signaling cascades.