The role of vascular endothelial growth factor in angiogenesis

PPAR-alpha Ligands as Potential Therapeutic Agents for Wet Age-Related Macular Degeneration

The peroxisome proliferator-activated receptors (PPAR's) are members of the steroid/thyroid nuclear receptor, superfamily of transcription factors. There are currently three known PPAR subtypes, α, β, and γ. The PPARs are now recognized participants in a number of biological pathways some of which are implicated in the pathogenesis of age-related macular degeneration (AMD). These include immune modulation, lipid regulation, and oxidant/antioxidant pathways important to the onset and progression of “dry” AMD, and vascular endothelial growth factor (VEGF) mediated pathways that stimulate choroidal neovascularization (CNV), characteristic of “wet” AMD. PPAR-α is found in retina and also on vascular cells important to formation of CNV. At this time, however, relatively little is known about potential contributions of PPAR-α to the pathogenesis of dry and wet AMD. This review examines current literature for potential roles of PPAR-α in the pathogenesis and potential treatment of AMD with emphasis on prevention and treatment of wet AMD.

Development of targeted therapy for squamous cell carcinomas of the head and neck

Targeted therapy is a very exciting era in the treatment of squamous cell carcinomas of the head and neck. After adding cetuximab to conventional chemotherapy and radiation therapy, we are strongly considering the role of induction chemotherapy with the addition of docetaxel. At the same time, other new treatments, especially targeted agents and novel combined regimens, are being evaluated in ongoing clinical trials. For example, several trials are attempting to combine docetaxel and cetuximab in chemoradiation or induction settings. However, in the near future we are likely to see a strong presence of targeted agents that have been found to be not only effective, but also less toxic than conventional chemotherapeutic agents. Their toxicity profiles make them eligible for addition to radiation treatment strategies, as well as other chemotherapy agents, or even for replacing these chemotherapy agents. In this article, we are going to review the indications and current role of cetuximab, tyrosine kinase inhibitors (gefitinib and erlotinib), dual inhibitors, IGF receptor inhibitors, as well as other agents that are in development for treatment of head and neck squamous cell carcinomas.

Protective effect of prostaglandin E1 on renal microvascular injury in rats of acute aristolochic acid nephropathy

BACKGROUND

To investigate the renal microvascular injury in acute aristolochic acid nephropathy (AAN) and the protective effects of prostaglandin E1 (PGE1) in acute AAN.

METHODS

Female Sprague-Dawley rats were randomly divided into three groups. The rats in PGE1 group received Caulis Aristolochia manshuriensis (CAM) decoction by gavage for 5 days, and PGE1 was given by vena caudalis before gavage. The rats in model group were gavaged with CAM for 5 days, and the same dose of 0.9% physiologic saline was given by vena caudalis. The rats in control group only received an equal daily volume of saline solution by gavage. Animals were killed at days 3, 5, and 7. Blood urea nitrogen (BUN), serum creatinine, and urinary protein were monitored before killing. Microvascular density was determined by JG12 immunostaining. The expression of angiogenic factor was assessed by vascular endothelial growth factor (VEGF). Tubulointerstitial hypoxia was assessed by hypoxia-inducible factor-1α (HIF-1α) expression.

RESULTS

CAM induced a significant decrease in VEGF expression and microvascular density in the kidney tissue, accompanied by a significant increase in HIF-1α, which reduced renal function and increased 24-h urinary protein excretion rates. PGE1 lessened the capillary loss, relieved hypoxia, and protected renal function. No significant pathological changes were found in control rats.

CONCLUSION

The renal microvascular injury in acute AAN is severe. PGE1 can significantly ameliorate the renal microvascular injury, relieve hypoxia, and protect renal function.

The effects of cadmium on VEGF-mediated angiogenesis in HUVECs

Cadmium (Cd) is a highly toxic element that causes morphologic alterations and dysfunction in blood vessels. The altered vascular function caused by cadmium has been implicated in a range of chronic diseases, including hypertension. The effects of cadmium are a multisystem phenomenon involving inflammation, hypertrophy, apoptosis, angiogenesis and important processes involved in vascular remodeling systems. Vascular endothelial growth factor (VEGF) plays a major role in cell growth and angiogenesis under pathologic conditions. VEGF secretion is related to anti-apoptosis protein expression and attenuates apoptosis in endothelial cells. This study examined the VEGF-dependent mechanisms of angiogenesis and apoptosis in cadmium-treated endothelial cells (HUVECs). The effects and mechanisms of cadmium in endothelial cells (HUVECs) were examined by exposing the cells to different doses of cadmium chloride (2.5-40 μ m). After the cadmium treatment, the angiogenesis and apoptosis mechanisms related to VEGF in cadmium-treated HUVECs were examined. As a result, the low concentration of cadmium increased the tube formation in HUVECs. In addition, cadmium at concentrations of 5 and 10 μ m increased VEGF secretion and VEGFR2 activity, which suggest that cadmium affects the growth of blood vessels. All three MAPK pathways, namely ERK, JNK and p38, were activated by cadmium in HUVECs. However, high concentrations of cadmium caused cell damage, disrupted tube formation and inhibited VEGF expression and the activities of VEGFR2 and MAPK in HUVECs. Cadmium has dual functions through VEGF-dependent mechanisms in a dose-dependent manner. In this study, the dual effects of cadmium might alter angiogenesis and induce apoptosis through VEGF pathways in HUVECs.

VEGF and its soluble receptor VEGFR-2 in hypertensive disorders during pregnancy: the Indian scenario

Hypertensive disorders are the most common medical problem encountered during pregnancy due to defective angiogenesis during placental development. Vascular endothelial growth factor (VEGF) is one of the angiogenic growth factors that stimulates angiogenesis. The recombinant form of its soluble receptor VEGF receptor-2 (sVEGFR-2) has anti-angiogenic activity. However, there is a paucity of information on serum VEGF and sVEGFR-2 concentrations in different sub-groups of hypertensive disorders during pregnancy. In this cross-sectional study, we evaluated the concentrations and the diagnostic utility of VEGF and sVEGFR-2 in gestational hypertension (GH, n=90), pre-eclampsia (PE, n=180), eclampsia (n=90) and control (n=180) pregnancy at different gestations. VEGF levels were significantly higher in PE and eclamptic (median=19.53 pg ml(-1); 60.36 pg ml(-1), P=0.0001) groups as compared with the control ones (median=18 pg ml(-1)). But, the serum sVEGFR-2 levels were found to be significantly decreased from GH to eclampsia groups (median=5196; 3972 pg ml(-1)) as compared with control groups (median=7417 pg ml(-1)). As the gestation advanced, there was an inverse association in the serum concentrations of sVEGFR-2 among the control, GH, PE and eclampsia groups. At both 34 and >34 weeks of gestations, higher sensitivity and specificity were observed for sVEGFR-2 in differentiating GH (50.8, 50%; 76.6, 76.6%), PE (63, 63%; 90, 90%) and eclampsia (65, 66.6%; 90, 90%) from the control pregnancy. This upregulation of VEGF and downregulation of sVEGFR-2 concentrations in different study groups may be due to hypoxia and could be involved intimately in the pathogenesis of these disorders. This study may contribute in understanding etio-pathogenesis of different hypertensive disorders during pregnancy.

Collagen IV contributes to nitric oxide-induced angiogenesis of lung endothelial cells

Nitric oxide (NO) mediates endothelial angiogenesis via inducing the expression of integrin α(v)β(3). During angiogenesis, endothelial cells adhere to and migrate into the extracellular matrix through integrins. Collagen IV binds to integrin α(v)β(3), leading to integrin activation, which affects a number of signaling processes in endothelial cells. In the present study, we evaluated the role of collagen IV in NO-induced angiogenesis. We found that NO donor 2,2'-(hydroxynitrosohydrazino)bis-ethanamine (NOC-18) causes increases in collagen IV mRNA and protein in lung endothelial cells and collagen IV release into the medium. Addition of collagen IV into the coating of endothelial culture increases endothelial monolayer wound repair, proliferation, and tube formation. Inhibition of collagen IV synthesis using gene silencing attenuates NOC-18-induced increases in monolayer wound repair, cell proliferation, and tube formation as well as in the phosphorylation of focal adhesion kinase (FAK). Integrin blocking antibody LM609 prevents NOC-18-induced increase in endothelial monolayer wound repair. Inhibition of protein kinase G (PKG) using the specific PKG inhibitor KT5823 or PKG small interfering RNA prevents NOC-18-induced increases in collagen IV protein and mRNA and endothelial angiogenesis. Together, these results indicate that NO promotes collagen IV synthesis via a PKG signaling pathway and that the increase in collagen IV synthesis contributes to NO-induced angiogenesis of lung endothelial cells through integrin-FAK signaling. Manipulation of collagen IV could be a novel approach for the prevention and treatment of diseases such as alveolar capillary dysplasia, severe pulmonary arterial hypertension, and tumor invasion.

Androgen stimulates endothelial cell proliferation via an androgen receptor/VEGF/cyclin A-mediated mechanism

Growing evidences support that androgen displays beneficial effects on cardiovascular functions although the mechanism of androgen actions remains to be elucidated. Modulation of endothelial cell growth and function is a potential mechanism of androgen actions. We demonstrated in the present study that androgens [dihydrotestosterone (DHT) and testosterone], but not 17β-estradiol, produced a time- and dose-dependent induction of cell proliferation in primary human aortic endothelial cells (HAECs) as evident by increases in viable cell number and DNA biosynthesis. Real-time qRT-PCR analysis showed that DHT induced androgen receptor (AR), cyclin A, cyclin D1, and vascular endothelial growth factor (VEGF) gene expression in a dose- and time-dependent manner. The addition of casodex, a specific AR antagonist, or transfection of a specific AR siRNA blocked DHT-induced cell proliferation and target gene expression, indicating that the DHT effects are mediated via AR. Moreover, coadministration of SU5416 to block VEGF receptors, or transfection of a specific VEGF-A siRNA to knockdown VEGF expression, produced a dose-dependent blockade of DHT induction of cell proliferation and cyclin A gene expression. Interestingly, roscovitine, a selective cyclin-dependent kinase inhibitor, also blocked the DHT stimulation of cell proliferation with a selective inhibition of DHT-induced VEGF-A expression. These results indicate that androgens acting on AR stimulate cell proliferation through upregulation of VEGF-A, cyclin A, and cyclin D1 in HAECs, which may be beneficial to cardiovascular functions since endothelial cell proliferation could assist the repair of endothelial injury/damage in cardiovascular system.

Association of vascular endothelial growth factor gene polymorphisms with susceptibility to epithelial ovarian cancer

BACKGROUND

Vascular endothelial growth factor (VEGF) is a major angiogenic factor involved in a number of pathological processes, including neovascularization, a crucial step in the development of solid malignancies. The aim of this study was to investigate the association of polymorphisms in the VEGF gene with susceptibility to epithelial ovarian cancer (EOC).

METHODS

This case-control study included 303 EOC patients and 303 healthy controls. Genotyping of the VEGF gene polymorphisms at j460C/T, j1154G/A, j2578C/A, and +936C/T were performed by polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

No significant difference was found in allele and genotype distributions of the -460C/T, +936C/T, and -2578C/A polymorphisms between patients and controls. However, the frequencies of -1154G/A genotype and allele were significantly different between the two groups (P = 0.037, P = 0.013). Compared with the G/A + A/A genotype, the G/G genotype could significantly increase the risk of developing EOC (odds ratio, 1.64; 95% confidence interval, 1.12Y2.39). The haplotype analysis suggested that the -460T/ -1154A/ -2578C haplotype exhibited a decrease in the risk of developing EOC compared with the -460T/ -1154G/ -2578C haplotype (odds ratio, 0.644; 95% confidence interval, 0.415-0.999).

CONCLUSIONS

The study suggested a possible association between the VEGF -1154G/A polymorphism with susceptibility to EOC, but there is no support for an association of the VEGF -460C/T, +936C/T, and -2578C/A polymorphisms with the risk for EOC.

Growth factors and gene expression of stem cells: bone marrow compared with peripheral blood

PURPOSE

To evaluate and compare the presence of cytokines and growth factors in both bone marrow (BM) and peripheral blood.

MATERIAL

Samples of autogenous BM aspirate and peripheral blood (PB) from 7 patients ranging in age from 49 to 80 years were analyzed with real-time polymerase chain reaction technology to identify and compare selected gene expression for specific cytokines and growth factors. The genes selected for analysis included those involved in osteogenesis, hematogenesis, angiogenesis, extracellular matrix molecules, and cell-adhesion molecules. A maximum of 4 cc';s BM aspirate was taken from the anterior iliac crest and 0.5 mL of venous blood was drawn from each of 7 patients.

RESULTS

The results of the analysis indicate that both circulating blood and BM aspirate contain large quantities of a host of growth factors and cytokines. More platelet-derived growth factor is expressed in patient blood (PB) than in BM. Vascular endothelial growth factor alpha is expressed slightly greater in BM and vascular endothelial growth factor beta is slightly more prominent in PB. Transforming growth factors (TGFs) TGFA, TGFB1, and TGFB3 were equally expressed in BM and PB, and TGFB2 had a greater expression in PB. Bone morphogenetic proteins (BMPs) 1, 3, 7, 8B, R1A, and PR2 were almost equally expressed in BM and PB. BMPs 4 and 6 were expressed greater in PB. BMP2 was expressed more in BM. Extracellular matrix factors were equally expressed in PB and BM. Mesenchymal stem cell lineage markers varied in PB and BMA, and hematopoietic stem cell lineage markers were expressed more in PB than BM. Gene expression for angiogenic factors were equally expressed in PB and BM.

CONCLUSION

In this investigation, specific cytokines and growth factors in BM are compared with those in peripheral blood. Each has similar biologic effects and most expressed equally in BM and PB. However, BMP2 and vascular endothelial growth factor alpha had greater expression in BM.

Transcriptional and post-transcriptional regulation of proangiogenic factors by the unfolded protein response

Background

Inadequate extracellular conditions can adversely affect the environment of the ER and impinge on the maturation of nascent proteins. The resultant accumulation of unfolded proteins activates a signal transduction pathway, known as the unfolded protein response, which serves primarily to protect the cell during stress and helps restore homeostasis to the ER.

Principal Findings

Microarray analysis of the unfolded protein response in a human medulloblastoma cell line treated with thapsigargin revealed that, in addition to known targets, a large number of proangiogenic factors were up-regulated. Real-Time PCR analyses confirmed that four of these factors, VEGFA, FGF2, angiogenin and IL8, were transcriptionally up-regulated in multiple cell lines by various ER stress inducers. Our studies on VEGFA regulation revealed that XBP-1(S), a UPR-inducible transcription factor, bound to two regions on the VEGFA promoter, and analysis of XBP-1 null mouse embryonic fibroblasts revealed that it contributes to VEGFA expression in response to ER stress. ATF4, another UPR-inducible transcription factor, also binds to the VEGFA gene, although its contribution to VEGFA transcription appeared to be fairly modest. We also found that VEGFA mRNA stability is increased in response to UPR activation, via activation of AMP kinase, demonstrating that increased mRNA levels occur at two regulatory points. In keeping with the mRNA levels, we found that VEGFA protein is secreted at levels as high as or higher than that achieved in response to hypoxia.

Conclusions and Significance

Our results indicate that the UPR plays a significant role in inducing positive regulators of angiogenesis. It also regulates VEGFA expression at transcriptional, post-transcriptional and post-translational levels and is likely to have widespread implications for promoting angiogenesis in response to normal physiological cues as well as in pathological conditions like cancer.

Oxygen tension differentially influences osteogenic differentiation of human adipose stem cells in 2D and 3D cultures

Skeletal defects commonly suffer from poor oxygen microenvironments resulting from compromised vascularization associated with injury or disease. Adipose stem cells (ASCs) represent a promising cell population for stimulating skeletal repair by differentiating toward the osteogenic lineage or by secreting trophic factors. However, the osteogenic or trophic response of ASCs to reduced oxygen microenvironments is poorly understood. Moreover, a direct comparison between 2D and 3D response of ASCs to hypoxia is lacking. Thus, we characterized the osteogenic and angiogenic potential of human ASCs under hypoxic (1%), normoxic (5%), and atmospheric (21%) oxygen tensions in both 2D and 3D over 4 weeks in culture. We detected greatest alkaline phosphatase activity and extracellular calcium deposition in cells cultured in both 2D and 3D under 21% oxygen, and reductions in enzyme activity corresponded to reductions in oxygen tension. ASCs cultured in 1% oxygen secreted more vascular endothelial growth factor (VEGF) over the 4-week period than cells cultured in other conditions, with cells cultured in 2D secreting VEGF in a more sustained manner than those in 3D. Expression of osteogenic markers revealed temporal changes under different oxygen conditions with peak expression occurring earlier in 3D. In addition, the increase of most osteogenic markers was significantly higher in 2D compared to 3D cultures at 1% and 5% oxygen. These results suggest that oxygen, in conjunction with dimensionality, affects the timing of the differentiation program in ASCs. These findings offer new insights for the use of ASCs in bone repair while emphasizing the importance of the culture microenvironment.

Inkjet-based biopatterning of bone morphogenetic protein-2 to spatially control calvarial bone formation

The purpose of this study was to demonstrate spatial control of osteoblast differentiation in vitro and bone formation in vivo using inkjet bioprinting technology and to create three-dimensional persistent bio-ink patterns of bone morphogenetic protein-2 (BMP-2) and its modifiers immobilized within microporous scaffolds. Semicircular patterns of BMP-2 were printed within circular DermaMatrix human allograft scaffold constructs. The contralateral halves of the constructs were unprinted or printed with BMP-2 modifiers, including the BMP-2 inhibitor, noggin. Printed bio-ink pattern retention was validated using fluorescent or (125)I-labeled bio-inks. Mouse C2C12 progenitor cells cultured on patterned constructs differentiated in a dose-dependent fashion toward an osteoblastic fate in register to BMP-2 patterns. The fidelity of spatial restriction of osteoblastic differentiation at the boundary between neighboring BMP-2 and noggin patterns improved in comparison with patterns without noggin. Acellular DermaMatrix constructs similarly patterned with BMP-2 and noggin were then implanted into a mouse calvarial defect model. Patterns of bone formation in vivo were comparable with patterned responses of osteoblastic differentiation in vitro. These results demonstrate that three-dimensional biopatterning of a growth factor and growth factor modifier within a construct can direct cell differentiation in vitro and tissue formation in vivo in register to printed patterns.

Effects of a Chinese herbal health formula, "Gan-Lu-Yin", on angiogenesis

According to the known effects of each ingredient, Gan-Lu-Yin (GLY), a traditional Chinese herbal formula, has the potential to be an antiangiogenic agent. The purpose of this study was to explore the putative effect of GLY on antiangiogenesis. An ethanol extract of GLY was tested on chicken chorioallantoic membrane (CAM) and human umbilical vein endothelial cells (HUVEC) to evaluate the effects of GLY extract on cell proliferation, migration, and tube formation. The results showed that treatment with 1.0 mg/mL of GLY extract could markedly reduce cell migration and in vitro tube formation of HUVEC, and 1.5 mg/mL of GLY extract was sufficient to inhibit proliferation of HUVEC. The expression level of vascular endothelial growth factor (VEGF) of HUVEC was significantly decreased by 1.5 and 2.0 mg/mL of GLY extract. In chicken CAM assay, all tested concentrations of GLY extract were found to reduce the capillary mesh on the CAM of fertilized eggs. The inhibitory effects of GLY extract (1 mg/mL) were also found on tumor cell-induced HUVEC proliferation and tube formation. These observations suggested that GLY extract has an inhibitory effect on angiogenesis, which in turn may prevent tumor growth, and its mechanism might be partially associated with blocking VEGF protein expression of HUVEC.

VEGF 936C>T polymorphism and breast cancer risk: evidence from 5,729 cases and 5,868 controls

Vascular endothelial growth factor (VEGF) is one of the most potent endothelial cell mitogens and plays an important role in angiogenesis. Many published studies have evaluated the association between the VEGF 936C>T polymorphism and breast cancer risk. However, the published findings are inconsistent. In order to derive a more precise estimation of the association, a meta-analysis was performed in this study. A total of eight studies including 5,729 breast cancer cases and 5,868 controls were identified. Overall, no significant associations between the VEGF 936C>T polymorphism and breast cancer risk were found for TT versus CC (OR 0.93, 95% CI 0.73-1.19), CT versus CC (OR 0.91, 95% CI 0.77-1.09), TT/CT versus CC (OR 0.92, 95% CI 0.78-1.08), and TT versus CT/CC (OR 0.96, 95% CI 0.75-1.21). In the subgroup analysis by ethnicity, source of controls, and menopausal status, there was still no significant association detected in any of the genetic models. In summary, our results suggest that the VEGF 936C>T polymorphism may not contribute to breast cancer susceptibility.

Inhibition of human breast cancer xenograft growth by cruciferous vegetable constituent benzyl isothiocyanate

Benzyl isothiocyanate (BITC), a constituent of cruciferous vegetables such as garden cress, inhibits growth of human breast cancer cell lines in culture. The present study was undertaken to determine in vivo efficacy of BITC against MDA-MB-231 human breast cancer xenografts. The BITC administration retarded growth of MDA-MB-231 cells subcutaneously implanted in female nude mice without causing weight loss or any other side effects. The BITC-mediated suppression of MDA-MB-231 xenograft growth correlated with reduced cell proliferation as revealed by immunohistochemical analysis for Ki-67 expression. Analysis of the vasculature in the tumors from BITC-treated mice indicated smaller vessel area compared with control tumors based on immunohistochemistry for angiogenesis marker CD31. The BITC-mediated inhibition of angiogenesis in vivo correlated with downregulation of vascular endothelial growth factor (VEGF) receptor 2 protein levels in the tumor. Consistent with these results, BITC treatment suppressed VEGF secretion and VEGF receptor 2 protein levels in cultured MDA-MB-231 cells. Moreover, the BITC-treated MDA-MB-231 cells exhibited reduced capacity for migration compared with vehicle-treated control cells. In contrast to cellular data, BITC administration failed to elicit apoptotic response as judged by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. In conclusion, the present study demonstrates in vivo anti-cancer efficacy of BITC against MDA-MB-231 xenografts in association with reduced cell proliferation and suppression of neovascularization. These preclinical observations merit clinical investigation to determine efficacy of BITC against human breast cancers.

Gender differences in cardiovascular disease: hormonal and biochemical influences

OBJECTIVE

Atherosclerosis is a complex process characterized by an increase in vascular wall thickness owing to the accumulation of cells and extracellular matrix between the endothelium and the smooth muscle cell wall. There is evidence that females are at lower risk of developing cardiovascular disease (CVD) as compared to males. This has led to an interest in examining the contribution of genetic background and sex hormones to the development of CVD. The objective of this review is to provide an overview of factors, including those related to gender, that influence CVD.

METHODS

Evidence analysis from PubMed and individual searches concerning biochemical and endocrine influences and gender differences, which affect the origin and development of CVD.

RESULTS

Although still controversial, evidence suggests that hormones including estradiol and androgens are responsible for subtle cardiovascular changes long before the development of overt atherosclerosis.

CONCLUSION

Exposure to sex hormones throughout an individual's lifespan modulates many endocrine factors involved in atherosclerosis.

Radiotherapy in combination with vascular-targeted therapies

BACKGROUND

Given the critical role of tumor vasculature in tumor development, considerable efforts have been spent on developing therapeutic strategies targeting the tumor vascular network. A variety of agents have been developed, with two general approaches being pursued. Antiangiogenic agents (AAs) aim to interfere with the process of angiogenesis, preventing new tumor blood vessel formation. Vascular-disrupting agents (VDAs) target existing tumor vessels causing tumor ischemia and necrosis. Despite their great therapeutic potential, it has become clear that their greatest clinical utility may lie in combination with conventional anticancer therapies. Radiotherapy is a widely used treatment modality for cancer with its distinct therapeutic challenges. Thus, combining the two approaches seems reasonable.

CONCLUSIONS

Strong biological rationale exist for combining vascular-targeted therapies with radiation. AAs and VDAs were shown to alter the tumor microenvironment in such a way as to enhance responses to radiation. The results of preclinical and early clinical studies have confirmed the therapeutic potential of this new treatment strategy in the clinical setting. However, concerns about increased normal tissue toxicity, have been raised.

Leptin upregulates VEGF in breast cancer via canonic and non-canonical signalling pathways and NFkappaB/HIF-1alpha activation

High levels of VEGF and leptin are strongly linked to worse prognosis of breast cancer. Leptin signalling upregulates VEGF in human and mouse mammary tumor cells (MT), but the specific molecular mechanisms are largely unknown. Pharmacologic and genetic approaches were used to dissect the mechanism of leptin regulation of VEGF protein and mRNA in MT (4T1, EMT6 and MMT). A series of VEGF-promoter Luc-reporters (full-length and transcription factor-binding deletions) were transfected into MT to analyze leptin regulation of VEGF transcription. Deletion analysis of VEGF promoter and RNA knockdown shows that HIF-1alpha and NFkappaB are essentials for leptin regulation of VEGF. Leptin activation of HIF-1alpha was mainly linked to canonic (MAPK, PI-3K) and non-canonic (PKC, JNK and p38 MAP) signalling pathways. Leptin non-canonic signalling pathways (JNK, p38 MAP and to less extent PKC) were linked to NFkappaB activation. SP1 was involved in leptin regulation of VEGF in 4T1 cells. AP1 was not involved and AP2 repressed leptin-induced increase of VEGF. Overall, these data suggest that leptin signalling regulates VEGF mainly through HIF-1alpha and NFkappaB. These results delineate a comprehensive mechanism for leptin regulation of VEGF in MT. Disruption of leptin signalling could be used as a novel way to treat breast cancer.

Vascular endothelial growth factor (VEGF)-A: role on cardiac angiogenesis following myocardial infarction

The current study is to determine the regulatory role of VEGF-A in cardiac angiogenesis following myocardial infarction (MI). Cardiac angiogenic response and temporal/spatial expression of VEGF-A/VEGF receptors (VEGFR) were examined at 1, 2, 6, 12 h and 1, 2, 3, 4, 7, 14, and 28 days postMI. We found that following MI, newly formed vessels first appeared at the border zone between noninfarcted and infarcted myocardium as early as day 3 and subsequently in the infarcted myocardium. Vascular density in the infarcted myocardium peaked at day 7 and then gradually declined. VEGF-A mRNA started to increase at the border zone at 2 h postMI, reached peak at 12 h, declined at day 1, and returned to normal levels at day 2 and thereafter. VEGF-A protein levels at the border zone were only increased during day 1 postMI. VEGF-A within the infarcted myocardium levels, however, was persistently suppressed postMI. VEGFR expression was significantly increased only at the border zone at day 1, but not in the later stages. The expression of VEGF-A/VEGFR remained unchanged in the noninfarcted myocardium. Thus, the early rise of VEGF-A/VEGFR at the border zone suggests that VEGF-A initiates the cardiac angiogenic response postMI, but short-lived VEGF-A/VEGFR activation at the border zone and consistently suppressed VEGF-A within the infarcted myocardium suggests that VEGF-A may not be crucial to the later stages of angiogenesis.

Estrogen regulation of placental angiogenesis and fetal ovarian development during primate pregnancy

During human and nonhuman primate pregnancy, an extensive blood vessel network is established within the villous placenta to support fetal growth and follicles develop within the fetal ovary to provide a pool of oocytes for reproductive function in adulthood. These two important developmental events occur in association with a progressive increase in placental estrogen production and levels. This review will describe the developmental processes required for placental vascularization and fetal follicular maturation and recent studies which show that estrogen has an important role in regulating these events.

A review of the current research on the role of bFGF and VEGF in angiogenesis

Basic fibroblast growth factor and vascular endothelial growth factor are thought to play a synergistic role in angiogenesis. They are released into the wound bed during haemostasis and promote the formation of new blood vessels.

Vascular endothelial growth factor receptor-2 inhibition promotes cell death and limits endothelial cell proliferation in a neonatal rodent model of stroke

BACKGROUND AND PURPOSE

Recent studies in neonatal rodent stroke models suggest that recovery is due in part to upregulation of hypoxia-inducible factor-1-a and its downstream target, vascular endothelial growth factor. Vascular endothelial growth factor is upregulated after a hypoxic insult and is involved in neuronal survival, angiogenesis, and neurogenesis during the recovery process.

METHODS

We performed a 1.5-hour transient middle cerebral artery occlusion in 10-day-old rats with injury verified by diffusion-weighted MRI during occlusion to determine the effects of vascular endothelial growth factor receptor-2 (VEGFR2) inhibition on injury, apoptosis, and angiogenesis. Two days after reperfusion, the pups received either the VEGFR inhibitor, SU5416 (10 mg/kg per dose) or vehicle (1% dimethyl sulfoxide) for 3 days.

RESULTS

VEGFR2 inhibition worsened injury 7 days after injury when compared with the vehicle-treated and injury-alone groups (P<0.01). Furthermore, receptor inhibition was associated with increased VEGFR2 expression 5 days after injury (P<0.05) and increased spectrin cleavage with a shift in favor of the calpain-mediated, caspase-3-independent cleavage (P<0.01). Increased areas of cleaved caspase-3 staining were seen in treated rats at 7 days (P<0.01) There were no differences in gliosis or macrophage recruitment as measured by glial fibrillary acidic protein and Iba-1 expression at this time point. Lastly, VEGFR2 inhibition did not affect the overall vessel surface area but reduced endothelial cell proliferation in injured caudate.

CONCLUSIONS

Inhibition of VEGFR2 signaling worsens injury, affects cell death, and reduces endothelial cell proliferation after neonatal stroke. Injury exacerbation may be in part due to a shift of cell fate from apoptosis to necrosis on the continuum spectrum of cell death as well as effects on angiogenesis in the injured brain.

Calpain inhibitor SNJ-1945 attenuates events prior to angiogenesis in cultured human retinal endothelial cells

PURPOSE

Vascular endothelial growth factor (VEGF) is an important regulator of angiogenesis and microvascular permeability. VEGF-induced cytoskeletal reorganization plays a crucial role in angiogenesis. Cytoskeletal organization in endothelial cells is regulated by calpain proteases (EC 3.4.22.17). Calpains are a family of 14 calcium-regulated, intracellular cysteine proteases, which modulate cellular functions by limited, specific proteolysis. Calpain 1 (mu-calpain) and calpain 2 (m-calpain) are the 2 major typical calpain isoforms and are responsible for most calpain activity in endothelial cells. The purpose of the present study was to determine if an orally available form of calpain inhibitor, SNJ-1945, prevented angiogenesis induced by VEGF in cultured retinal endothelial cells.

METHODS

Human retinal microvascular endothelial cells (HRMEC) were incubated with VEGF (60-100 ng/mL) for 24 h. Calcium uptake was measured with Fluo8. Total calpain activity was measured using fluorescent-labeled casein substrate, and separate activities for calpains 1 and 2 were assessed by casein zymography. Proteolysis of endogenous calpain substrate alpha-spectrin in situ was analyzed by immunoblotting. Angiogenesis in vitro was evaluated by measuring cell migration and tube formation into Matrigel.

RESULTS

Incubation of HRMEC with VEGF resulted in calcium uptake, increased activity of mainly calpain 2, and increased calpain proteolysis of alpha-spectrin. Treatment of endothelial cells with calpain inhibitor SNJ-1945 reversed VEGF-mediated tube formation and cell motility.

CONCLUSIONS

Inhibition of angiogenesis by specific calpain inhibitor in the presence of VEGF supported our hypothesis that calpains may be involved in VEGF-mediated angiogenesis in retinal endothelial cells. Therefore, manipulating calpain activity by calpain inhibitor SNJ-1945 might provide a promising therapy for management of pathological angiogenesis, such as that occurring in proliferative retinopathy and age-related macular degeneration with neovascularization.

Mesenchymal stem cells expressing osteogenic and angiogenic factors synergistically enhance bone formation in a mouse model of segmental bone defect

The potential of mesenchymal stem cells (MSC) in tissue regeneration is increasingly gaining attention. There is now accumulating evidence that MSC make an important contribution to postnatal vasculogenesis. During bone development and fracture healing, vascularization is observed before bone formation. The present study determined the potential of MSC, transduced ex vivo with a recombinant adeno-associated virus 6 (rAAV6) encoding bone morphogenetic protein 2 (BMP2) and vascular endothelial growth factor (VEGF) in a mouse model of segmental bone defect created in the tibiae of athymic nude mice. Mouse MSC that were mock-transduced or transduced with rAAV6-BMP2:VEGF were systemically transplanted following radiographic confirmation of the osteotomy. Effects of the therapy were determined by enzyme-linked immunosorbent assay measurements for BMP2 and VEGF, dual-energy X-ray absorptiometry (DXA) for bone density, three-dimensional microcomputed tomography (microCT) for bone and capillary architecture, and histomorphometry for bone remodeling. Results of these analyses indicated enhanced bone formation in the group that received BMP2+VEGF-expressing MSC compared to other groups. The therapeutic effects were accompanied by increased vascularity and osteoblastogenesis, indicating its potential for effective use while treating difficult nonunion bone defects in humans.

Angiogenesis inhibition in cancer therapy: platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) and their receptors: biological functions and role in malignancy

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in a variety of in vivo models. VEGF gene transcription is induced in particular in hypoxic cells. In developmental angiogenesis, the role of VEGF is demonstrated by the finding that the loss of a single VEGF allele results in defective vascularization and early embryonic lethality. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. In situ hybridization studies demonstrate expression of VEGF mRNA in the majority of human tumors. Platelet-derived growth factor (PDGF) is mainly believed to be an important mitogen for connective tissue, and also has important roles during embryonal development. Its overexpression has been linked to different types of malignancies. Thus, it is important to understand the physiology of VEGF and PDGF and their receptors as well as their roles in malignancies in order to develop antiangiogenic strategies for the treatment of malignant disease.

Rap1 and its effector KRIT1/CCM1 regulate beta-catenin signaling

KRIT1, also called CCM1, is a member of a multiprotein complex that contains the products of the CCM2 and PDCD10 (also known as CCM3) loci. Heterozygous loss of any of the genes that encode these proteins leads to cerebral cavernous malformations (CCM), which are vascular lesions that are found in around 0.5% of humans. KRIT1 mediates the stabilization of beta-catenin-containing endothelial cell-cell junctions downstream of the Rap1 GTPase. Here, we report that Rap1 and KRIT1 are negative regulators of canonical beta-catenin signaling in mice and that hemizygous Krit1 deficiency exacerbates beta-catenin-driven pathologies. Depletion of endothelial KRIT1 caused beta-catenin to dissociate from vascular endothelial (VE)-cadherin and to accumulate in the nucleus with consequent increases in beta-catenin-dependent transcription. Activation of Rap1 inhibited beta-catenin-dependent transcription in confluent endothelial cells; this effect required the presence of intact cell-cell junctions and KRIT1. These effects of KRIT1 were not limited to endothelial cells; the KRIT1 protein was expressed widely and its depletion increased beta-catenin signaling in epithelial cells. Moreover, a reduction in KRIT1 expression also increased beta-catenin signaling in vivo. Hemizygous deficiency of Krit1 resulted in a ~1.5-fold increase in intestinal polyps in the Apc(Min/+) mouse, which was associated with increased beta-catenin-driven transcription. Thus, KRIT1 regulates beta-catenin signaling, and Krit1(+/-) mice are more susceptible to beta-catenin-driven intestinal adenomas.

Differential apoptotic response of human cancer cells to organoselenium compounds

PURPOSE

Selenium (Se) compounds are well known to inhibit cell proliferation and induce cell death in human cancer cells. Respective chemical forms of Se are intracellularly metabolized via complicated pathways, which target distinct molecules and exhibit varying degrees of anti-carcinogenicity in different cancer types; however, the precise mechanisms by which Se activates apoptosis remain poorly understood.

METHODS

The effects of Se compounds, Se-methylselenocysteine (MSC), selenomethionine (SeMet), and selenite on cell proliferation, apoptosis and its pathway in established human carcinoma cell lines (HSC-3, -4, A549, and MCF-7) were investigated. Cancer cells were treated with each Se compound during different periods. Cell apoptosis, caspase activity and ER stress markers were analyzed by flow cytometric or immunoblotting analysis, respectively.

RESULTS

We examined four cell lines for their sensitivity to MSC and SeMet in comparison with selenite. SeMet increased apoptotic cells in p53-positive A549 cells, whereas MSC increased apoptotic cells in p53-mutated HSC-3 cells. High activities of caspase-3, -8 and -9 were observed during apoptosis, and a pan-caspase inhibitor, z-VAD-fmk, rescued the cell viability of HSC-3 cells exposed to MSC. In addition, the occurrence of endoplasmic reticulum (ER) stress was suggested by the observation that levels of phosphorylated eIF2alpha and caspase-12 activity are increased in Se-treated cells. Selenite and MSC were accompanied with the concurrent reduction of phosphorylated Akt levels, and the inhibitory effects of these Se compounds on vascular endothelial growth factor expression were observed with identical patterns.

CONCLUSION

The present findings demonstrate that Se-induced apoptosis in carcinoma cells is basically a caspase-dependent process involving complicated mechanisms. Activation of both the intrinsic apoptotic pathway and ER stress pathway plays a major and concurrent role, while p53 activation seems to have only a functional role in SeMet.

Engineering craniofacial structures: facing the challenge

The human innate regenerative ability is known to be limited by the intensity of the insult together with the availability of progenitor cells, which may cause certain irreparable damage. It is only recently that the paradigm of tissue engineering found its way to the treatment of irreversibly affected body structures with the challenge of reconstructing the lost part. In the current review, we underline recent trials that target engineering of human craniofacial structures, mainly bone, cartilage, and teeth. We analyze the applied engineering strategies relative to the selection of cell types to lay down a specific targeted tissue, together with their association with an escorting scaffold for a particular engineered site, and discuss their necessity to be sustained by growth factors. Challenges and expectations for facial skeletal engineering are discussed in the context of future treatment.

Corticotropin-releasing hormone attenuates vascular endothelial growth factor release from human HaCaT keratinocytes

OBJECTIVES

Corticotropin-releasing hormone (CRH) is a central component of the local hypothalamic-pituitary-adrenal (HPA) axis, which has a functional equivalent in the skin. To determine whether CRH and its receptor, CRH-R1, modulate the expression of vascular endothelial growth factor (VEGF), which is overexpressed in psoriatic epidermis and plays a causal role in the pathogenesis of psoriasis, we investigated the effect of CRH on the expression of VEGF in a human keratinocyte cell line (HaCaT) and whether this effect is via the mitogen-activated protein kinase (MAPK) signal transduction pathways.

METHODS

Real-time RT-PCR, ELISA assay and western blot were used in the present study to investigate the expression of VEGF in CRH-treated HaCaT cells.

RESULTS

The mRNA and protein levels of VEGF in CRH-treated HaCaT cells were significantly attenuated. However, this downregulation was abrogated by pretreatment with antalarmin, SB203580 and SP600125; pretreatment with PD98059 did not attenuate the effects of CRH on the expression of VEGF. In addition, CRH treatment induced rapid phosphorylation of p38 MAPK and JNK1/2, and antalarmin, SB203580 and SP600125 inhibited CRH-induced phosphorylation of p38 MAPK and JNK1/2.

CONCLUSIONS

CRH might downregulate the expression of VEGF through the CRH-R1 and MAPK (p38 MAPK and JNK1/2) signaling pathways in human HaCaT cells.

Inhibitory effects of epigallocatechin-3 gallate, a polyphenol in green tea, on tumor-associated endothelial cells and endothelial progenitor cells

The polyphenol epigallocatechin-3 gallate (EGCG) in green tea suppresses tumor growth by direct action on tumor cells and by inhibition of angiogenesis, but it is not known whether it specifically inhibits tumor angiogenesis. We examined the anti-angiogenic effect of EGCG on tumor-associated endothelial cells (TEC), endothelial progenitor cells (EPC), and normal endothelial cells (NEC). EGCG suppressed the migration of TEC and EPC but not NEC. EGCG also inhibited the phosphorylation of Akt in TEC but not in NEC. Furthermore, vascular endothelial growth factor-induced mobilization of EPC into circulation was inhibited by EGCG. MMP-9 in the bone marrow plasma plays key roles in EPC mobilization into circulation. We observed that expression of MMP-9 mRNA was downregulated by EGCG in mouse bone marrow stromal cells. In an in vivo model, EGCG suppressed growth of melanoma and reduced microvessel density. Our study showed that EGCG has selective anti-angiogenic effects on TEC and EPC. It is suggested that EGCG could be a promising angiogenesis inhibitor for cancer therapy.

Alendronate inhibits VEGF expression in growth plate chondrocytes by acting on the mevalonate pathway

Bisphosphonates decrease chondrocyte turnover at the growth plate and impact bone growth. Likewise vascular endothelial growth factor (VEGF) plays an important role in endochondral bone elongation by influencing chondrocyte turnover at the growth plate. To investigate whether the action of bisphosphonate on the growth plate works through VEGF, VEGF protein expression and isoform transcription in endochondral chondrocytes isolated from growing mice and treated with a clinically used bisphosphonate, alendronate, were assessed. Alendronate at 10µM and 100µM concentrations decreased secreted VEGF protein expression but not cell associated protein. Bisphosphonates are known to inhibit the mevalonate intracellular signaling pathway used by VEGF. Addition of the mevalonate pathway intermediates farnesol (FOH) and geranylgeraniol (GGOH) interacted with the low concentration of alendronate to further decrease secreted VEGF protein whereas FOH partially restored VEGF protein secretion when combined with the high alendronate. Similar to the protein data, the addition of alendronate decreased VEGF mRNA isoforms. VEGF mRNA levels were rescued by the GGOH mevalonate pathway intermediate at the low alendronate dose whereas neither intermediate consistently restored the VEGF mRNA levels at the high alendronate dose. Thus, the bisphophonate alendronate impairs growth plate chondrocyte turnover by down-regulating the secreted forms of VEGF mRNA and protein by inhibiting the mevalonate pathway.

The biology of platelet-rich plasma and its application in trauma and orthopaedic surgery: a review of the literature

Although mechanical stabilisation has been a hallmark of orthopaedic surgical management, orthobiologics are now playing an increasing role. Platelet-rich plasma (PRP) is a volume of plasma fraction of autologous blood having platelet concentrations above baseline. The platelet alpha granules are rich in growth factors that play an essential role in tissue healing, such as transforming growth factor-beta, vascular endothelial growth factor, and platelet-derived growth factor. PRP is used in various surgical fields to enhance bone and soft-tissue healing by placing supraphysiological concentrations of autologous platelets at the site of tissue damage. The easily obtainable PRP and its possible beneficial outcome hold promise for new regenerative treatment approaches. The aim of this literature review was to describe the bioactivities of PRP, to elucidate the different techniques for PRP preparation, to review animal and human studies, to evaluate the evidence regarding the use of PRP in trauma and orthopaedic surgery, to clarify risks, and to provide guidance for future research.

Angiogenic properties of sustained release platelet-rich plasma: characterization in-vitro and in the ischemic hind limb of the mouse

BACKGROUND

While single growth factor has limitation to induce optimal neovascularization, platelet-rich plasma (PRP) is an autologous reserver of various growth factors. However, little is known about the mechanism of PRP-related neovascularization.The objective of this investigation was to characterize the angiogenic and growth factor content of PRP and to determine, in vitro, its effect on endothelial cell proliferation. Additionally, this experiment sought to determine the effectiveness of different compositions of PRP (solution versus sustained release) on perfusion and neovascularization in a murine model of hind limb ischemia.

METHODS

Different growth factors were measured by enzyme-linked immunosorbent assay (ELISA). In vivo study, we used gelatin hydrogel as a sustained release carrier for growth factors in PRP. We induced hind limb ischemia by excising right femoral artery in wild type C57BL6 mice. After surgery, mice were randomly assigned to four experimental groups; control (C), 100 muL of sustained release form of platelet-poor plasma (PPP), 100 muL of solution form of PRP (PRP-sol), 100 muL of sustained release form of PRP (PRP-sr); each formulation was administered via an intramuscular injection to the ischemic hind limb. Endpoint evaluations were blood perfusion by laser Doppler perfusion image, vascular density by anti Von Willebrand factor (vWF), and mature vessel density by anti smooth muscle actin (SMA) antibody. Green fluorescent protein (GFP+) transgenic mice were generated by transplantation of bone marrow derived mononuclear cells to wild type C57BL6 mice, and finally CD34+ cell in the ischemic site of transgenic mice was detected by staining with anti-CD34 antibody.

RESULTS

In vitro study showed that PRP containing different growth factors induces endothelial cell proliferation and capillary tube formation. In vivo study demonstrated that sustained release of PRP increased perfusion of ischemic tissue as measured by laser Doppler perfusion imaging (LDPI) (57 +/- 12, 56 +/- 9, 72 +/- 7, 98 +/- 4 for groups C, PPP, PRP-sol, and PRP-sr, respectively; P < .05); capillary density (151 +/- 16, 158 +/- 12, 189 +/- 39, 276 +/- 39 for groups C, PPP, PRP-sol, and PRP-sr, respectively, P < .05) and mature vessel density (28 +/- 2, 31 +/- 3, 52 +/- 10, 85 +/- 13 for groups C, PPP, PRP-sol, and PRP-sr, respectively, P < .05) . Sustained release PRP also increases CD34+ cells in the ischemic site of transgenic mice (6 +/- 3 vs 18 +/- 5/mm(2) for groups control and PRP-sr respectively, P < .05).

CONCLUSION

Sustained release of PRP containing potent angiogenic growth factors restores blood perfusion presumably by stimulating angiogenesis, arteriogenesis, as well as vasculogenesis in the mouse hind limb ischemia.

CLINICAL RELEVANCE

PRP is a natural reserver of various growth factors that can be collected autologously and is costeffective. Thus for clinical use, no special considerations concerning antibody formation and infection risk are needed.Some clinical devices to automatically prepare PRP are available at present. PRP are consistently being used clinically inthe department of orthopedics and plastic surgery (oral, maxillary facial) for a long time. On the basis of researchevidence, some publications have reported positive results in either bone or soft tissue healing. However, some researchconcludes that there is no or little benefit from PRP. This is likely due to faster degradation of growth factors in PRP sincesome authors suggest using sustained release form of PRP to deliver optimal effect of PRP. Gelatin hydrogel is also beingused clinically as a slow, sustained release of carrier for growth factors in our center recently.

Total chemical synthesis of the D2 domain of human VEGF receptor 1

The interaction of the vascular endothelial growth factor (VEGF) with its cellular receptors exerts a central role in the regulation of angiogenesis. Among these receptors, the VEGF receptor 1 may be implicated in pathological angiogenesis. Here, we report the first total chemical synthesis of the VEGF-binding domain of the VEGF receptor 1. Aggregation issues were overcome by the use of a low-substituted resin and the stepwise introduction of pseudoproline dipeptides and Dmb-glycines. The folding of the protein was achieved by air oxidation and its biological activity was verified on ELISA-based assays.

Suppression of tumor growth by palm tocotrienols via the attenuation of angiogenesis

Previous studies have revealed that tocotrienol-rich fractions (TRF) from palm oil inhibit the proliferation and the growth of solid tumors. The anticancer activity of TRF is said to be caused by several mechanisms, one of which is antiangiogenesis. In this study, we looked at the antiangiogenic effects of TRF. In vitro investigations of the antiangiogenic activities of TRF, delta-tocotrienol (deltaT3), and alpha-tocopherol (alphaToc) were carried out in human umbilical vein endothelial cells (HUVEC). TRF and deltaT3 significantly inhibited cell proliferation from 4 microg/ml onward (P < 0.05). Cell migration was inhibited the most by deltaT3 at 12 microg/ml. Anti-angiogenic properties of TRF were carried out further in vivo using the chick embryo chorioallantoic membrane (CAM) assay and BALB/c mice model. TRF at 200 microg/ml reduced the vascular network on CAM. TRF treatment of 1 mg/mouse significantly reduced 4T1 tumor volume in BALB/c mice. TRF significantly reduced serum vascular endothelial growth factor (VEGF) level in BALB/c mice. In conclusion, this study showed that palm tocotrienols exhibit anti-angiogenic properties that may assist in tumor regression.

The dose-effectiveness of intranasal VEGF in treatment of experimental stroke

The aim of the present study was to assess the dose-effectiveness of intranasal (IN) vascular endothelial growth factor (VEGF)in the treatment of experimental stroke. Sprague-Dawley rats were randomized into four groups as IN low (100 microg/ml), IN middle (200 microg/ml) and IN high (500 microg/ml) VEGF-treated group, and IN saline-treated group (n=12), given recombinant human VEGF 165 or saline intranasally. Focal cerebral ischemia was induced by transient (90 min) middle cerebral artery occlusion (MCAO) method. Behavioral neurological deficits were assessed 1, 7 and 14 d after the onset of MCAO. Rats were sacrificed at 14 d, the brain sections were stained and an image analysis system was used to calculate the infarct volume. Microvessels were labeled by FITC-dextran and the segment lengths, diameters and number of microvessels were measured by Image Pro-Plus Version 6.0 software. Fourteen days post MCAO, infarct volume significantly reduced (P<0.01) in rats which received the middle dose of IN VEGF when compared to IN saline. And middle dose of VEGF significantly improved behavioral recovery (P<0.01). No significant difference in the behavioral recovery and infarct volume was observed between the saline-treated group and the low or high VEGF-treated groups (P>0.05). Compared to IN saline, middle and high doses of VEGF significantly increased the segment length, diameter and number of microvessels (P<0.01). No significant difference in the segment length, diameter and number of microvessels was observed between the IN saline-treated group and the low VEGF-treated group (P>0.05). The middle dose of IN VEGF was most effective on reducing infarct volume, improving behavioral recovery and enhancing angiogenesis in stroke brain, which can be used in the following treatments to further evaluate the effect of VEGF.

Lipoxin A4: anti-inflammatory and anti-angiogenic impact on endothelial cells

Lipoxins (LX) are a class of eicosanoid that possesses a wide spectrum of antiinflammatory and proresolution bioactions. Here we have investigated the impact of the endogenously produced eicosanoid LXA(4) on endothelial cell inflammatory, proliferative, and antigenic responses. Using HUVECs we demonstrate that LXA(4) inhibits vascular endothelial growth factor (VEGF)-stimulated inflammatory responses including IL-6, TNF-alpha, IFN-gamma and IL-8 secretion, as well as endothelial ICAM-1 expression. Interestingly, LXA(4) up-regulated IL-10 production from HUVECs. Consistent with these antiinflammatory and proresolution responses to LXA(4), we demonstrate that LXA(4) inhibited leukotriene D(4) and VEGF-stimulated proliferation and angiogenesis as determined by tube formation of HUVECs. We have explored the underlying molecular mechanisms and demonstrate that LXA(4) pretreatment is associated with the decrease of VEGF-stimulated VEGF receptor 2 (KDR/FLK-1) phosphorylation and downstream signaling events including activation of phospholipase C-gamma, ERK1/2, and Akt.

Anti-angiogenesis approach to genitourinary cancer treatment

Angiogenesis plays a crucial role in the survival, proliferation, and metastatic potential of several tumors, including genitourinary (GU) cancers. Over the last decade, increasing basic science and clinical research have led to the approval of several angiogenesis inhibitors. GU tumors are unique in its pathogenesis whereby specific pathways, such as involvement of the Von Hippel-Lindau gene in clear cell renal cell cancer and aberrant overexpression of vascular endothelial growth factor in prostatic cancers and transitional cell bladder cancers, allow for potential targeting using angiogenesis inhibitors. This review discusses the biologic pathways as well as the rationale for using angiogenesis inhibitors in renal cell, prostate, and transitional cell bladder cancers. This review also focuses on pivotal trials and emerging data on the use of these inhibitors.

Mechanisms and targets for angiogenic therapy after stroke

Stroke remains a major health problem worldwide, and is the leading cause of serious long-term disability. Recent findings now suggest that strategies to enhance angiogenesis after focal cerebral ischemia may provide unique opportunities to improve clinical outcomes during stroke recovery. In this mini-review, we survey emerging mechanisms and potential targets for angiogenic therapies in brain after stroke. Multiple elements may be involved, including growth factors, adhesion molecules and progenitor cells. Furthermore, cross talk between angiogenesis and neurogenesis may also provide additional substrates for plasticity and remodeling in the recovering brain. A better understanding of the molecular interplay between all these complex pathways may lead to novel therapeutic avenues for tackling this difficult disease.

Smoking and sVEGFR-1: circulating maternal concentrations and placental expression

Smoking reduces the expression of VEGFR-1 in non-pregnant women. In pregnant women it reduces the risk of pre-eclampsia, which in turn is associated with increased placental expression of VEGFR-1 and increased maternal circulating soluble VEGFR-1 (sVEGFR-1). We therefore hypothesized that smoking might affect VEGFR-1 expression in pregnant women. In maternal plasma sVEGFR-1 concentrations during the third trimester in both smoking (median 1088, range 834-1362ng/L, n=20) and non-smoking (728, 719-1336ng/L, n=19) women were higher than during the second trimester (smokers 374, 291-683ng/L, n=6, p>0.05; non-smokers 375, 290-667ng/L, n=22, p<0.001). No difference was observed between smokers and non-smokers. Secretion of sVEGFR-1 into the culture medium, as well as the pattern and intensity of immunostaining in first trimester placenta were similar in tissue from smoking (n=22) and non-smoking (n=20) women. Thus, contrary to our hypothesis, smoking does not affect circulating maternal sVEGFR-1 concentrations or placental secretion of sVEGFR-1 or expression of VEGFR-1 in vitro.