Reciprocal relation between VEGF and NO in the regulation of endothelial integrity

Endothelial Progenitor Cells: A Review of Molecular Mechanisms in the Pathogenesis and Endovascular Treatment of Intracranial Aneurysms

This comprehensive review explores the multifaceted role of endothelial progenitor cells (EPCs) in vascular diseases, focusing on their involvement in the pathogenesis and their contributions to enhancing the efficacy of endovascular treatments for intracranial aneurysms (IAs). Initially discovered as CD34+ bone marrow-derived cells implicated in angiogenesis, EPCs have been linked to vascular repair, vasculogenesis, and angiogenic microenvironments. The origin and differentiation of EPCs have been subject to debate, challenging the conventional notion of bone marrow origin. Quantification methods, including CD34+ , CD133+ , and various assays, reveal the influence of factors, like age, gender, and comorbidities on EPC levels. Cellular mechanisms highlight the interplay between bone marrow and angiogenic microenvironments, involving growth factors, matrix metalloproteinases, and signaling pathways, such as phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK). In the context of the pathogenesis of IAs, EPCs play a role in maintaining vascular integrity by replacing injured and dysfunctional endothelial cells. Recent research has also suggested the therapeutic potential of EPCs after coil embolization and flow diversion, and this has led the development of device surface modifications aimed to enhance endothelialization. The comprehensive insights underscore the importance of further research on EPCs as both therapeutic targets and biomarkers in IAs.

The role of cellular crosstalk in the progression of diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common complications of diabetes, and its main manifestations are progressive proteinuria and abnormal renal function, which eventually develops end stage renal disease (ESRD). The pathogenesis of DN is complex and involves many signaling pathways and molecules, including metabolic disorders, genetic factors, oxidative stress, inflammation, and microcirculatory abnormalities strategies. With the development of medical experimental techniques, such as single-cell transcriptome sequencing and single-cell proteomics, the pathological alterations caused by kidney cell interactions have attracted more and more attention. Here, we reviewed the characteristics and related mechanisms of crosstalk among kidney cells podocytes, endothelial cells, mesangial cells, pericytes, and immune cells during the development and progression of DN and highlighted its potential therapeutic effects.

Erbu Zhuyu decoction improves endometrial angiogenesis via uterine natural killer cells and the PI3K/Akt/eNOS pathway a mouse model of embryo implantation dysfunction

BACKGROUND

We investigated the effect of Erbu Zhuyu decoction (EBZY) on angiogenesis via uterine natural killer (uNK) cells and the PI3K/Akt/eNOS pathway in embryo implantation dysfunction (EID) mice.

METHODS

Pregnant mice were randomly divided into blank, model, EBZY, progynova, and aspirin groups. Uteri were excised on the 5th day of pregnancy for analysis.

RESULTS

Mice in the model group showed pale uteri, a reduced implantation rate, and lower expression levels of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt), endothelial nitric oxide synthase (eNOS) and nitric oxide (NO). Compared to the model group, implantation rates in the medium-dose and high-dose groups of EBZY were significantly higher (P < .05), PI3K and Akt mRNA expression levels in the low-dose group were significantly higher (P < .05, P < .01), and the expression of p-PI3K, p-Akt, and p-eNOS proteins in all treatment groups were significantly increased (P < .01, P < .05). The expression of NO was significantly increased in the low-dose and high-dose groups (P < .01, P < .05, respectively). The level of p-Akt protein in the high-dose group was significantly higher than those in the other treatment groups (P < .01, P < .05). There was no significant difference in the density of uNK cells (P > .05).

CONCLUSIONS

EBZY facilitated embryo implantation in EID mice by enhancing endometrial angiogenesis via activation of the PI3K/Akt/eNOS pathway, at least in part. There was no evidence to indicate that EBZY could adjust the expression of uNK.

Podocyte VEGF-A Knockdown Induces Diffuse Glomerulosclerosis in Diabetic and in eNOS Knockout Mice

Vascular endothelial growth factor-a (VEGF-A) and nitric oxide (NO) are essential for glomerular filtration barrier homeostasis, and are dysregulated in diabetic kidney disease (DKD). While NO availability is consistently low in diabetes, both high and low VEGF-A have been reported in patients with DKD. Here we examined the effect of inducible podocyte VEGF-A knockdown (VEGF^KD) in diabetic mice and in endothelial nitric oxide synthase knockout mice (eNOS^−/−). Diabetes was induced with streptozotocin using the Animal Models of Diabetic Complications Consortium (AMDCC) protocol. Induction of podocyte VEGF^KD led to diffuse glomerulosclerosis, foot process effacement, and GBM thickening in both diabetic mice with intact eNOS and in non-diabetic eNOS^−/−:VEGF^KD mice. VEGF^KD diabetic mice developed mild proteinuria and maintained normal glomerular filtration rate (GFR), associated with extremely high NO and thiol urinary excretion. In eNOS^−/−:VEGF^KD (+dox) mice severe diffuse glomerulosclerosis was associated with microaneurisms, arteriolar hyalinosis, massive proteinuria, and renal failure. Collectively, data indicate that combined podocyte VEGF-A and eNOS deficiency result in diffuse glomerulosclerosis in mice; compensatory NO and thiol generation prevents severe proteinuria and GFR loss in VEGF^KD diabetic mice with intact eNOS, whereas VEGF^KD induction in eNOS^−/−:VEGF^KD mice causes massive proteinuria and renal failure mimicking DKD in the absence of diabetes. Mechanistically, we identify VEGF^KD-induced abnormal S-nitrosylation of specific proteins, including β3-integrin, laminin, and S-nitrosoglutathione reductase (GSNOR), as targetable molecular mechanisms involved in the development of advanced diffuse glomerulosclerosis and renal failure.

Excess adiponectin in eyes with progressive ocular vascular diseases

Anti-vascular endothelial growth factor (VEGF) therapies are now the first-line treatment for many ocular diseases, but some patients are non-responders to these therapies. The purpose of this study was to determine whether the level of adiponectin increased the pathogenesis of retinal edema and neovascularization in the retina of progressive ocular vascular diseases. We examined the role played by adiponectin in two types of cells and animal models which are retinal vein occlusion (RVO) and oxygen-induced retinopathy (OIR) mice. Our results showed that an injection of anti-adiponectin antibody ameliorated the retinal edema and ischemia through the depression of the expression level of VEGF-related factors and tight junction-related proteins in the retina of RVO mice. The intravitreal injection of anti-adiponectin antibody also decreased the degree of retinal neovascularization in an OIR mice. In addition, exposure of human retinal microvascular endothelial cells and human brain microvascular pericytes in culture to adiponectin increased both the vascular permeability and neovascularization through the increase of inflammatory factor and the dropout of the pericytes. These findings indicate that adiponectin plays a critical role in retinal edema and neovascularization, and adiponectin is a potential therapeutic target for the treatment of diabetic macular edema, proliferative diabetic retinopathy, and RVO.

Preventive effects of low-intensity endurance exercise for severe hyperglycemia-induced capillary regression in non-obese type 2 diabetes rat skeletal muscle

Although endurance exercise is effective for reducing diabetes‐related capillary regression, it is difficult to prescribe high‐intensity endurance exercise due to the potential worsening of complications in patients with severe hyperglycemia. Therefore, this study aimed to examine whether chronic low‐intensity exercise training may prevent severe hyperglycemia‐induced capillary regression of skeletal muscle in non‐obese type 2 diabetes. Non‐diabetic Sprague Dawley rats were assigned to a control (Con) group and an exercise (Ex) group. Likewise, spontaneously diabetic Torii rats were assigned to a diabetic sedentary (DM) group or a diabetic exercise (DMEx) group. Rats in the Ex and DMEx groups were placed on a motor‐driven treadmill running at low speed (15 m/min) for 60 min/day, 5 days/week, for 14 weeks. Serum glucose levels were significantly increased in the DM group, but not in the DMEx group. Although the capillary‐to‐fiber ratio in the plantaris muscle was significantly lower in the DM group compared to the control group, the ratio in the DMEx group was significantly higher compared to the DM group. Moreover, the succinate dehydrogenase activity and expression levels of vascular endothelial growth factor and peroxisome proliferator‐activated receptor γ coactivator‐1α (PGC‐1α) were reduced in the plantaris muscle of the DM group. However, those in the DMEx group were significantly higher than those in the DM group. These results indicate that low‐intensity chronic endurance exercise training has the potential to prevent the progression of capillary regression in the skeletal muscles of non‐obese type 2 diabetes patients with severe hyperglycemia.

Effect of low VEGF on lung development and function

Vascular endothelial growth factor (VEGF) is important for lung development and function but ideal mouse models are limited to decipher the quantitative relationship between VEGF expression levels and its proper development and pathogenesis. Human SPC promoter has been used to faithfully express genes or cDNAs in the pulmonary epithelium in many transgenic mouse models. In the study, a mouse model of lung-specific and reversible VEGF repression (hspc-rtTR^tg/+/Vegf^tetO/tetO) was generated. Human SPC promoter was used to drive lung-specific rtTR expression, a cDNA coding for doxycycline-regulated transcription repression protein. By crossing with Vegf^tetO/tetO mice, that has tetracycline operator sequences insertion in 5'-UTR region, it allows us to reversibly inhibit lung VEGF transcription from its endogenous level through doxycycline food, water or injection. The tissue-specific inhibition of VEGF is used to mimic abnormal expression levels of VEGF in lung. Reduced VEGF expression in lung is confirmed by quantitative real time PCR and immunoblotting. Lung development and structure was analyzed by histology analysis and found significantly affected under low VEGF. The pulmonary epithelium and alveolarization are found abnormal with swelling alveolar septum and enlargement of air space. Genome-wide gene expression analysis identified that immune activities are involved in the VEGF-regulated lung functions. The transgenic mouse model can be used to mimic human pulmonary diseases. The mouse model confirms the important regulatory roles of epithelial expressed VEGF in lung development and function. This mouse model is valuable for studying VEGF-regulated lung development, pathogenesis and drug screening under low VEGF expression.

Perigestational alcohol consumption induces altered early placentation and organogenic embryo growth restriction by disruption of trophoblast angiogenic factors

RESEARCH QUESTION

Maternal alcohol consumption produces fetal retardation and malformations, probably associated with placental defects. Does perigestational alcohol consumption up to organogenesis lead to abnormal placentation and embryo growth restriction by disrupting the vascular endothelial growth factor (VEGF) system in embryo-placental development?

DESIGN

Female mice were treated with 10% ethanol in drinking water before and up to day 10 of gestation. Control mice received ethanol-free water. After treatment, the trophoblastic tissue, embryo growth and the angiogenic VEGF pathway were analysed.

RESULTS

Female mice who had received treatment had resorbed and delayed implantation sites with poor ectoplacental cone development. Reduced trophoblastic area tissue from female mice who had received treatment had abnormal junctional zone and diminished labyrinthine vascularization. After treatment, the labyrinth had increased chorionic trophoblast proliferation, hypoxia inducible factor-1α immunoexpression but reduced apoptosis. The embryo growth was reduced concomitantly with low VEGF immunostaining but high endothelial nitric oxide synthase (eNOS) expression. In junctional and labyrinth of treated female mice, gene and protein immunoexpression of VEGF was reduced and the protein expression of FLT-1 increased compared with controls. Increased activation of kinase insert domain receptor receptor (phosphorylated KDR) and expression of eNOS were observed in placenta of treated female mice. Immunoexpression of metalloproteinase-9, however, was reduced in junctional zone but increased in labyrinth, compared with controls.

CONCLUSIONS

These data reveal inadequate expression of VEGF/receptors and angiogenic eNOS and metalloproteinase factors related to abnormal early placentation after perigestational alcohol ingestion, providing insight into aetiological factors underlying early placentopathy associated with intrauterine growth restriction caused by maternal alcohol consumption.

COVID-19-associated vasculitis and vasculopathy

The COVID-19 pandemic now totaling 13,000,000 cases and over 571,000 deaths has continued to teach the medical, scientific and lay communities about viral infectious disease in the modern era. Among the many lessons learned for the medical community is the potential for transmissibility and host infectivity of the SARS–CoV-2 virus. Moreover, it has become clear that the virus can affect any organ including the circulatory system, directly via either tissue tropism or indirectly stemming from inflammatory responses in the form of innate immunity, leukocyte debris such as cell-free DNA and histones and RNA viral particles. The following review considers COVID-19-associated vasculitis and vasculopathy as a defining feature of a virus-induced systemic disease with acute, subacute and potential chronic health implications.

Reactive Jumps Preserve Skeletal Muscle Structure, Phenotype, and Myofiber Oxidative Capacity in Bed Rest

Identification of countermeasures able to prevent disuse-induced muscle wasting is crucial to increase performance of crew members during space flight as well as ameliorate patient’s clinical outcome after long immobilization periods. We report on the outcome of short but high-impact reactive jumps (JUMP) as countermeasure during 60 days of 6° head-down tilt (HDT) bed rest on myofiber size, type composition, capillarization, and oxidative capacity in tissue biopsies (pre/post/recovery) from the knee extensor vastus lateralis (VL) and deep calf soleus (SOL) muscle of 22 healthy male participants (Reactive jumps in a sledge, RSL-study 2015–2016, DLR:envihab, Cologne). Bed rest induced a slow-to-fast myofiber shift (type I –>II) with an increased prevalence of hybrid fibers in SOL after bed rest without jumps (control, CTRL, p = 0.016). In SOL, JUMP countermeasure in bed rest prevented both fast and slow myofiber cross-sectional area (CSA) decrements (p = 0.005) in CTRL group. In VL, bed rest only induced capillary rarefaction, as reflected by the decrease in local capillary-to-fiber ratio (LCFR) for both type II (pre vs. post/R + 10, p = 0.028/0.028) and type I myofibers (pre vs. R + 10, p = 0.012), which was not seen in the JUMP group. VO_2maxFiber (pL × mm^–1 × min^–1) calculated from succinate dehydrogenase (SDH)-stained cryosections (OD_{660 nm}) showed no significant differences between groups. High-impact jump training in bed rest did not prevent disuse-induced myofiber atrophy in VL, mitigated phenotype transition (type I – >II) in SOL, and attenuated capillary rarefaction in the prime knee extensor VL however with little impact on oxidative capacity changes.

Endothelial Function: A Short Guide for the Interventional Cardiologist

An impaired function of the coronary endothelium is an important determinant of all stages of atherosclerosis, from initiation, to mediation of functional phenomena—such as spasm and plaque erosion, to atherothrombotic complications. Endothelial function is modified by therapies, including stent implantation. Finally, endothelial function changes over time, in response to physical stimuli and pharmocotherapies, and its assessment might provide information on how individual patients respond to specific therapies. In this review, we describe the role of the endothelium in the continuum of coronary atherosclerosis, from the perspective of the interventional cardiologist. In the first part, we review the current knowledge of the role of endothelial (dys)function on atherosclerotic plaque progression/instabilization and on the mechanisms of ischemia, in the absence of coronary artery stenosis. In the second part of this review, we describe the impact of coronary artery stenting on endothelial function, platelet aggregation, and inflammation.

Low molecular-weight fucoidan protects against hindlimb ischemic injury in type 2 diabetic mice through enhancing endothelial nitric oxide synthase phosphorylation

BACKGROUND

Diabetes mellitus (DM) complications are associated with ischemic injury. Angiogenesis is a therapeutic strategy for diabetic foot. The aim of this study was to investigate the possible angiogenic effect of low molecular weight fucoidan (LMWF) in diabetic peripheral arterial disease (PAD).

METHODS

Diabetic db/db mice and age-matched C57BL/6 mice underwent femoral artery ligation followed by LMWF (30, 60, 80 mg/kg per day, p.o.) or cilostazol (30 mg/kg/day, p.o.) treatment for 6 weeks. Endothelium-dependent vasodilation and blood flow of the hindlimb were measured. Histological and western blot analyses of CD34, vascular endothelial growth factor (VEGF), eNOS, and inflammatory factors in the gastrocnemius were performed. The effects of LMWF were confirmed in human umbilical vein endothelial cells (HUVEC).

RESULTS

Diabetic mice with ligation exhibited hindlimb ulceration, hydrosarca, and necrosis, increased expression of inflammatory factors, and decreased levels of VEGF and eNOS phosphorylation. Treatment with LMWF markedly ameliorated foot lesions, suppressed expression of inflammatory factors, and improved plantar perfusion by promoting endothelium-dependent vasodilation and revascularization in diabetic PAD mice. In high-glucose treated HUVEC, LMWF (40 μg/mL) reversed blunted endothelial cell proliferation, migration, and tube formation, and promoted eNOS phosphorylation and VEGF expression, whereas HUVEC pretreatment with 100 μmol/L N^G -nitro-l-arginine methyl ester, an eNOS antagonist, markedly inhibited the effects of LMWF.

CONCLUSION

This study demonstrates that LMWF alleviates hindlimb ischemic damage, at least in part by promoting eNOS phosphorylation, nitric oxide production, and VEGF expression, resulting in enhanced angiogenesis in the ischemic region.

The effects of stenting on coronary endothelium from a molecular biological view: Time for improvement?

Coronary artery stenting following balloon angioplasty represents the gold standard in revascularization of coronary artery stenoses. However, stent deployment as well as percutaneous transluminal coronary angioplasty (PTCA) alone causes severe injury of vascular endothelium. The damaged endothelium is intrinsically repaired by locally derived endothelial cells and by circulating endothelial progenitor cells from the blood, leading to re‐population of the denuded regions within several weeks to months. However, the process of re‐endothelialization is often incomplete or dysfunctional, promoting in‐stent thrombosis and restenosis. The molecular and biomechanical mechanisms that influence the process of re‐endothelialization in stented segments are incompletely understood. Once the endothelium is restored, endothelial function might still be impaired. Several strategies have been followed to improve endothelial function after coronary stenting. In this review, the effects of stenting on coronary endothelium are outlined and current and future strategies to improve endothelial function after stent deployment are discussed.

Prognostic value of coronary collaterals in patients with acute coronary syndromes

BACKGROUND

The presence of good coronary collateral circulation (CCC) can protect and preserve myocardium from ischemia, increase myocardial contractility, and reduce adverse clinical events. However, its impact on mortality is still a topic of debate, particularly in acute coronary syndrome (ACS). The aim of this study was to investigate the association of CCC with cardiac risk factors and in-hospital mortality in patients hospitalized with a diagnosis of ACS.

METHODS

The study population included 2286 patients with ACS who underwent coronary angiography and were found to have at least 90% significant lesion in at least one major coronary artery. The CCC was graded according to the Rentrop classification. The patients were classified into a poor CCC group (Rentrop grades 0-1, n=1859) or a good CCC group (Rentrop grades 2-3, n=427).

RESULTS

Patients with good CCC had more high-risk patient characteristics such as older age, higher rate of Killip class of at least 2 at admission, lower left ventricular ejection fraction, and impaired renal functions compared with the patients with poor CCC. In multivariate analysis, the presence of good CCC [odds ratio (OR): 2.000; 95% confidence interval: 1.116-3.585; P=0.020], left ventricular ejection fraction less than 40% (OR: 2.381; P=0.003), Killip class of at least 2 at admission (OR: 3.609; P<0.001), age of at least 65 years (OR: 2.975; P=0.003), and hemoglobin (OR: 0.797; P=0.003) were independent predictors of in-hospital mortality.

CONCLUSION

In contrast to previous studies, our study did not confirm a beneficial role of good CCC in patients with ACS; the presence of good CCC was even independently associated with increased in-hospital mortality in the multivariate analysis.

High Levels of Urinary Vascular Endothelial Growth Factor in Women with Severe Preeclampsia

Elevated plasma VEGF concentrations in preeclampsia are associated with local placental ischemia and endothelial dysfunction. We investigated the urinary VEGF excretion in women with severe preeclampsia (n=37) and its relation with proteinuria compared to that in healthy pregnant (n=32) and non-pregnant women (n=30). In women with severe preeclampsia VEGF levels were 54.0 (19.9–192.4) ng/mmol creatinine, significantly (p<0.0001) higher than levels in pregnant controls (28.2 (6.7–63.0) ng/mmol creatinine) and non-pregnant controls (29.5 (10.1–59.1) ng/mmol creatinine). Proteinuria was not significantly correlated with urinary VEGF levels. In conclusion, high urinary VEGF concentrations in severe preeclampsia might reflect increased renal production of VEGF rather than elevated VEGF levels in the systemic circulation.

Inhibition of endothelial nitric oxyde synthase increases capillary formation via Rac1-dependent induction of hypoxia-inducible factor-1α and plasminogen activator inhibitor-1

Disruption of endothelial homeostasis results in endothelial dysfunction, characterised by a dysbalance between nitric oxide (NO) and reactive oxygen species (ROS) levels often accompanied by a prothrombotic and proproliferative state. The serine protease thrombin not only is instrumental in formation of the fibrin clot, but also exerts direct effects on the vessel wall by activating proliferative and angiogenic responses. In endothelial cells, thrombin can induce NO as well as ROS levels. However, the relative contribution of these reactive species to the angiogenic response towards thrombin is not completely clear. Since plasminogen activator inhibitor-1 (PAI-1), a direct target of the proangiogenic transcription factors hypoxia-inducible factors (HIFs), exerts prothrombotic and proangiogenic activities we investigated the role of ROS and NO in the regulation of HIF-1α, PAI-1 and capillary formation in response to thrombin. Thrombin enhanced the formation of NO as well as ROS generation involving the GTPase Rac1 in endothelial cells. Rac1-dependent ROS formation promoted induction of HIF-1α, PAI-1 and capillary formation by thrombin, while NO reduced ROS bioavailability and subsequently limited induction of HIF-1α, PAI-1 and the angiogenic response. Importantly, thrombin activation of Rac1 was diminished by NO, but enhanced by ROS. Thus, our findings show that capillary formation induced by thrombin via Rac1-dependent activation of HIF-1 and PAI-1 is limited by the concomitant release of NO which reduced ROS bioavailability. Rac1 activity is sensitive to ROS and NO, thereby playing an essential role in fine tuning the endothelial response to thrombin.

Alpha adrenergic receptor blockade increases capillarization and fractional O2 extraction and lowers blood flow in contracting human skeletal muscle

AIM

To assess the effect of elevated basal shear stress on angiogenesis in humans and the role of enhanced skeletal muscle capillarization on blood flow and O₂ extraction.

METHODS

Limb haemodynamics and O₂ extraction were measured at rest and during one-leg knee-extensor exercise (12 and 24 W) in 10 healthy untrained young men before and after 4-week treatment with an α₁ receptor-antagonist (Terazosin, 1-2 mg day^-1 ). Corresponding biopsies were taken from the m. vastus lateralis.

RESULTS

Resting leg blood flow was increased by 57% 6 h following Terazosin treatment (P < 0.05), while basal capillary-to-fibre ratio was 1.69 ± 0.08 and increased to 1.90 ± 0.08 after treatment (P < 0.05). Leg O₂ extraction during knee-extensor exercise was higher (4-5%; P < 0.05), leg blood flow and venous lactate levels lower (6-7%; P < 0.05), while leg VO₂ was not different after Terazosin treatment.

CONCLUSIONS

These results demonstrate that daily treatment with an α-adrenergic receptor blocker induces capillary growth in human skeletal muscle, likely due to increased shear stress. The increase in capillarization resulted in an increased fractional O₂ extraction, a lower blood flow and venous lactate levels in the exercising leg. The increase in capillarization, and concomitant functional readouts in the exercising leg, may provide a basis for novel angiotherapy.

The impact of vascular endothelial growth factor +405 C/G polymorphism on long-term outcome and severity of coronary artery disease

BACKGROUND

The association between genetic variations of vascular endothelial growth factor (VEGF) gene and the risk for atherosclerosis has been hypothesized. We aimed to assess the relationship between rs2010963 (+405 C/G) polymorphism and presence, severity, and outcome of coronary artery disease (CAD) in an Iranian cohort.

METHODS

Genotyping of VEGF rs2010963 polymorphism was performed on 520 individuals, comprising 347 patients with documented coronary artery disease based on angiography report and 173 individuals with normal coronary arteries, using the TaqMan real-time PCR method. In final, 484 subjects were followed up over a 5-year period for cardiovascular-related outcomes.

RESULTS

C allele of VEGF rs2010963 polymorphism was related to increase risk for CAD and also slightly to 5-year cardiovascular mortality. The 5-year survival in C and G allele subgroups were 92.3% and 94.3% in CAD group and 95.7% and 98.0% in non-CAD group, respectively.

CONCLUSIONS

Vascular endothelial growth factor rs2010963 polymorphism may be associated with the presence of CAD and its long-term survival, but not with its severity. To the best of our knowledge, this is the first report of genetic association between rs2010963 SNP and CAD-related death. It can be thus suggested that rs2010963 VEGF gene can be considered as a genetic risk predictor for CAD and its outcomes.

Redox regulation of gasotransmission in the vascular system: A focus on angiogenesis

Reactive oxygen species have emerged as key participants in a broad range of physiological and pathophysiological processes, not least within the vascular system. Diverse cellular functions which have been attributed to some of these pro-oxidants within the vasculature include the regulation of blood pressure, neovascularisation and vascular inflammation. We here highlight the emerging roles of the enzymatically-generated reaction oxygen species, O₂^- and H₂O₂, in the regulation of the functions of the gaseous signalling molecules: nitric oxide (NO), carbon monoxide (CO), and hydrogen sulphide (H₂S). These gasotransmitters are produced on demand from distinct enzymatic sources and in recent years it has become apparent that they are capable of mediating a number of homeostatic processes within the cardiovascular system including enhanced vasodilation, angiogenesis, wound healing and improved cardiac function following myocardial infarction. In common with O₂^- and/or H₂O₂ they signal by altering the functions of target proteins, either by the covalent modification of thiol groups or by direct binding to metal centres within metalloproteins, most notably haem proteins. The regulation of the enzymes which generate NO, CO and H₂S have been shown to be influenced at both the transcriptional and post-translational levels by redox-dependent mechanisms, while the activity and bioavailability of the gasotransmitters themselves are also subject to oxidative modification. Within vascular cells, the family of nicotinamide adenine dinucleotide phosphate oxidases (NAPDH oxidases/Noxs) have emerged as functionally significant sources of regulated O₂^- and H₂O₂ production and accordingly, direct associations between Nox-generated oxidants and the functions of specific gasotransmitters are beginning to be identified. This review focuses on the current knowledge of the redox-dependent mechanisms which regulate the generation and activity of these gases, with particular reference to their roles in angiogenesis.

Effects of kallidinogenase on retinal edema and size of non-perfused areas in mice with retinal vein occlusion

Kallidinogenase has been used to treat retinal vein occlusion (RVO) in patients, although there are no evidences on the effects of kallidinogenase on the retinal edema and the non-perfused areas in eyes with a RVO. We have established a murine RVO model with retinal edema and non-perfused areas. The purpose of this study was to evaluate the effects of kallidinogenase on the retinal edema and size of the non-perfused areas in the mouse RVO model. We evaluated the thickness of the retinal layers and size of the non-perfused areas, and the blood flow by laser speckle flowgraphy in RVO model. The effects of an intravenous injection of kallidinogenase on the retinal edema and size of the non-perfused areas were determined. In addition, the expressions of phosphorylated protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) were measured by Western blotting. Our results showed that kallidinogenase reduced the degree of retinal edema and size of the non-perfused areas by an increase in the blood flow in RVO model. Kallidinogenase also increased the levels of phosphorylated Akt and eNOS. These findings indicate that kallidinogenase acted through Akt/eNOS-dependent phosphorylation. Thus, kallidinogenase should be considered as a possible therapeutic agent for RVO patients.

Characterization of Vascular Endothelial Growth Factor (VEGF) in the Uterine Cervix over Pregnancy: Effects of Denervation and Implications for Cervical Ripening

Bilateral neurectomy of the pelvic nerve (BLPN) that carries uterine cervix-related sensory nerves induces dystocia, and administration of its vasoactive neuropeptides induces changes in the cervical microvasculature, resembling those that occur in the ripening cervix. This study was designed to test the hypothesis that (a) the cervix of pregnant rats expresses vascular endothelial growth factor (VEGF) and components of the angiogenic signaling pathway [VEGF receptors (Flt-1, KDR), activity of protein kinase B, Akt (phosphorylated Akt), and endothelial nitric oxide synthase (eNOS)] and von Willebrand Factor (vWF) and that these molecules undergo changes with pregnancy, and (b) bilateral pelvic neurectomy (BLPN) alters levels of VEGF concentration in the cervix. Using RT-PCR and sequencing, two VEGF isoforms, 120 and 164, were identified in the rat cervix. VEGF, VEGF receptor-1 (Flt-1), eNOS, and vWF immunoreactivities (ir) were localized in the microvasculature of cervical stroma. Their protein levels increased during pregnancy but decreased to control levels by 2 days postpartum. VEGF receptor-2 (KDR)-ir was confined to the epithelium of the endocervix. BLPN downregulated levels of VEGF by a third. Therefore, the components of the angiogenic signaling pathway are expressed in the cervix and change over pregnancy. Furthermore, angiogenic and sensory neuronal factors may be important in regulating the dynamic microvasculature in the ripening cervix and may subsequently play a role in cervical ripening and the birth process.

Therapeutic Angiogenesis Using Vascular Endothelial Growth Factor

Therapeutic angiogenesis using vascular endothelial growth factor can reduce tissue ischemia by simulating the natural process of angiogenesis. Vascular endothelial growth factor not only stimulates endothelial cells to proliferate and migrate, but also mobilizes endothelial progenitor cells and achieves vascular protection. Besides direct administration of angiogenic proteins, plasmids and viral vectors carrying angiogenic genes have been used. Animal experiments have shown promise with evidence of neovascularization and improved perfusion in the target myocardium. Initial phase I and II clinical trials results are encouraging and reflect the potential success of therapeutic angiogenesis as a clinical modality for the treatment of ischemic heart disease. This review discusses the role of vascular endothelial growth factor in therapeutic angiogenesis, along with the problems and considerations of this approach as a treatment strategy.

Role of Receptor Tyrosine Kinase Signaling in Renal Fibrosis

Renal fibrosis can be induced in different renal diseases, but ultimately progresses to end stage renal disease. Although the pathophysiologic process of renal fibrosis have not been fully elucidated, it is characterized by glomerulosclerosis and/or tubular interstitial fibrosis, and is believed to be caused by the proliferation of renal inherent cells, including glomerular epithelial cells, mesangial cells, and endothelial cells, along with defective kidney repair, renal interstitial fibroblasts activation, and extracellular matrix deposition. Receptor tyrosine kinases (RTKs) regulate a variety of cell physiological processes, including metabolism, growth, differentiation, and survival. Many studies from in vitro and animal models have provided evidence that RTKs play important roles in the pathogenic process of renal fibrosis. It is also showed that tyrosine kinases inhibitors (TKIs) have anti-fibrotic effects in basic research and clinical trials. In this review, we summarize the evidence for involvement of specific RTKs in renal fibrosis process and the employment of TKIs as a therapeutic approach for renal fibrosis.

Potential Role of Axonal Chemorepellent Slit2 in Modulating Adventitial Inflammation in a Rat Carotid Artery Balloon Injury Model

Leukocyte infiltration of adventitial and perivascular tissues is an early event in the development of vascular remodeling after injury. We investigated whether Slit/Robo-an axonal chemorepellent system in vertebrate and invertebrate development-is activated during the inflammatory phase that follows endothelial denudation. Using the rat carotid artery model of angioplasty, we conducted a time course analysis of mRNAs encoding Slit ligands (Slit2 and Slit3) and Robo receptors (Robo1, Robo2, and Robo4), as well as proinflammatory cell adhesion molecule (CAM) genes. Adventitial inflammatory cells were counted in immunostained arterial sections. E-selectin, vascular CAM-1, and intercellular CAM-1 were upregulated 2-3 hours after injury, followed by infiltration of neutrophils and monocytes as evidenced by real-time polymerase chain reaction, in situ hybridization, and immunohistochemistry. Slit2, Slit3, and Robo genes exhibited no expression changes at 3 hours; however, they were markedly upregulated 1 day after angioplasty. Intercellular CAM-1 expression was reduced by 50%, and the number of adventitial neutrophils decreased by >75% 1 day after angioplasty. Slit2 has been shown to be a potent chemorepelent of leukocytes, endothelial cells, and smooth muscle cells. Thus, we decided to further investigate the localization of Slit2 in injured vessels. Immunohistochemical stainings revealed the presence of Slit2 within the vessel wall and in the perivascular vasa vasorum of naive and injured arteries. Double immunohistochemical analyses showed that infiltrating monocytes expressed Slit2 in the perivascular and adventitial tissues of injured arteries 1 and 3 days postangioplasty. In addition, recombinant full-length Slit2 and Slit2-N/1118, an N-terminal fragment of Slit2, inhibited stromal cell-derived factor 1-mediated migration of circulating rat peripheral blood mononuclear cells. In summary, adventitial activation of CAM genes and neutrophil infiltration preceded upregulation of Slit/Robo genes. Sli2 expression colocalized with infiltrating inflammatory cells in the adventitial layer. This temporospatial association suggests that leukocyte chemorepellent Slit2 may be involved in halting the adventitial accumulation of inflammatory cells in injured vessels.

Insights into the diverse effects of nitric oxide on tumor biology

Among its many roles in cellular biology, nitric oxide (·NO) has long been associated with cancers both as a protumorigenic and as an antitumorigenic agent. The dual nature of this signaling molecule in varied settings is attributable to its temporal and concentration-dependent effects that produce different phenotypes. The steady-state ·NO concentration within the cell is a balance between its rate of enzymatic synthesis from the three nitric oxide synthase (NOS) isoforms and consumption via numerous metabolic pathways and demonstrates strong dependence on the tissue oxygen concentration. NOS expression and ·NO production are often deregulated and associated with numerous types of cancers with dissimilar prognostic outcomes. ·NO influences several facets of tumor initiation and progression including DNA damage, chronic inflammation, angiogenesis, epithelial-mesenchymal transition, and metastasis, to name a few. The role of ·NO as an epigenetic modulator has also recently emerged and has potentially important mechanistic implications in regulating transcription of oncogenes and tumor-suppressor genes. ·NO-derived cellular adducts such as dinitrosyliron complexes and the formation of higher nitrogen oxides further alter its cellular behavior. Among anticancer strategies, the use of NOS as a prognostic biomarker and modulation of ·NO production for therapeutic benefit have gained importance over the past decade. Numerous ·NO-releasing drugs and NOS inhibitors have been evaluated in preclinical and clinical settings to arrest tumor growth. Taken together, ·NO affects various arms of cancer signaling networks. An overview of this complex interplay is provided in this chapter.

Systemic levels of vascular endothelial growth factor before and after intravitreal injection of aflibercept or ranibizumab in patients with age-related macular degeneration: a randomised, prospective trial

PURPOSE

To evaluate the changes of vascular endothelial growth factor (VEGF) plasma levels after intravitreal injections of aflibercept or ranibizumab in patients with exudative age-related macular degeneration (AMD).

METHODS

Thirty-eight patients with exudative AMD were included in this randomised, prospective study. Nineteen patients were randomised to treatment with intravitreal aflibercept (2.0 mg) and 19 to intravitreal ranibizumab (0.5 mg). The concentration of VEGF was measured by ELISA just before the injection, after 7 days and 1 month. Twenty-two age- and sex-matched healthy patients without chorioretinal diseases served as control.

RESULTS

The median baseline plasma VEGF concentration was 61.0 pg/ml in the control group, 43.0 pg/ml in the aflibercept group and 59.0 pg/ml in the ranibizumab group (p=0.127). Seven days after intravitreal injection of aflibercept plasma levels were significantly reduced to values below the minimum detectable dose (MDD) in 17 of 19 patients (89.5%) resulting in a median VEGF concentration of <9 pg/ml (p<0.001). The reduction persisted throughout 1 month with values below the MDD in 5 of 19 patients (26.3%) and a median measurement of 17.0 pg/ml (p<0.001). In patients treated with ranibizumab no significant effects could be observed with a baseline VEGF of 59.0 pg/ml, 54.0 pg/ml at 7 days (p=0.776) and 58.5 pg/ml at 4 weeks of follow-up (p=0.670).

CONCLUSION

After intravitreal aflibercept injection, the systemic VEGF levels were significantly reduced throughout the observational period of 4 weeks. No significant systemic effects of intravitreal ranibizumab on plasma VEGF were observed.

Exercise-induced capillary growth in human skeletal muscle and the dynamics of VEGF

In skeletal muscle, growth of capillaries is an important adaptation to exercise training that secures adequate diffusion capacity for oxygen and nutrients even at high-intensity exercise when increases in muscle blood flow are profound. Mechanical forces present during muscle activity, such as shear stress and passive stretch, lead to cellular signaling, enhanced expression of angiogenic factors, and initiation of capillary growth. The most central angiogenic factor in skeletal muscle capillary growth is VEGF. During muscle contraction, VEGF increases in the muscle interstitium, acts on VEGF receptors on the capillary endothelium, and thereby stimulates angiogenic processes. A primary source of muscle interstitial VEGF during exercise is the skeletal muscle fibers which contain large stores of VEGF within vesicles. We propose that, during muscle activity, these VEGF-containing vesicles are redistributed toward the sarcolemma where the contents are secreted into the extracellular fluid. VEGF mRNA expression is increased primarily after exercise, which allows for a more rapid replenishment of VEGF stores lost through secretion during exercise. Future studies should focus on elucidating mechanisms and regulation of VEGF secretion.

Multi-facets of Corticotropin-releasing Factor in Modulating Inflammation and Angiogenesis

The family of corticotropin-releasing factor (CRF) composed of 4 ligands including CRF, urocortin (Ucn) 1, Ucn2, and Ucn3 is expressed both in the central nervous system and the periphery including the gastrointestinal tract. Two different forms of G protein coupled receptors, CRF₁ and CRF₂, differentially recognize CRF family members, mediating various biological functions. A large body of evidence suggests that the CRF family plays an important role in regulating inflammation and angiogenesis. Of particular interest is a contrasting role of the CRF family during inflammatory processes. The CRF family can exert both pro-and anti-inflammatory functions depending on the type of receptors, the tissues, and the disease phases. In addition, there has been a growing interest in a possible role of the CRF family in angiogenesis. Regulation of angiogenesis by the CRF family has been shown to modulate endogenous blood vessel formation, inflammatory neovascularization and cardiovascular function. This review outlines the effect of the CRF family and its receptors on 2 major biological events: inflammation and angiogenesis, and provides a possibility of their application for the treatment of inflammatory vascular diseases.

Treatment of palmar-plantar erythrodysesthesia (PPE) with topical sildenafil: a pilot study

PURPOSE

Palmar-plantar erythrodysesthesia (PPE) is a common chemotherapy and anti-VEGF multi-kinase inhibitor class-related toxicity that often results in debilitating skin changes and often limits the use of active anti-cancer regimens. Mechanistic and anecdotal clinical evidence suggested that topical application of sildenafil cream may help reduce the severity of PPE. Therefore, we conducted a randomized, double-blind, placebo-controlled pilot study to evaluate the feasibility, safety and efficacy of topical sildenafil cream for the treatment of PPE.

METHODS

Eligible subjects were required to have grade 1-3 PPE associated with either capecitabine or sunitinib. Subjects were randomized to receive 1 % topical sildenafil cream to the left extremities or right extremities and placebo cream on the opposite extremity. Two times per day, 0.5 mL of cream was applied to each affected hand/foot. The primary endpoint was improvement in PPE grading at any point on study. Clinical assessments were evaluated by NCI-CTC 4.0 grading and patient self-reported pain.

RESULTS

Ten subjects were enrolled, nine were evaluable for safety and efficacy. Five of nine subjects reported some improvement in foot pain and three of eight subjects for hand pain improvement. One of these subjects noted specific improvement in tactile function. No treatment-related toxicities were observed.

CONCLUSIONS

In this limited, single-center study, topical cream containing 1 % sildenafil is feasible to administer, is well-tolerated, and may mitigate PPE-related symptoms due to anti-cancer therapeutic agents. Further validation is necessary.

Bioactive lipids in pathological retinopathy

Diabetic retinopathy is a common condition that occurs in patients with diabetes with long-standing hyperglycemia that is characterized by inappropriate angiogenesis. This pathological angiogenesis could be a sort of physiological proliferative response to injury by the endothelium. Recent studies suggested that reactive oxygen species (ROS) play a significant role in this angiogenesis. Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor that plays a significant role in diabetic retinopathy. The interaction between VEGF and ROS, and theirs in turn with pro- and anti-inflammatory cytokines and anti-inflammatory bioactive lipid molecules such as lipoxins, resolvins, protectins, and maresins is particularly relevant to understand the pathophysiology of diabetic retinopathy and develop future therapeutic interventions.

Corticotropin-releasing Hormone and Its Biological Diversity toward Angiogenesis

Angiogenesis is the formation of new blood vessels from existing ones and an underlying cause of numerous human diseases, including cancer and inflammation. A large body of evidence indicates that angiogenic inhibitors have therapeutic potential in the treatment of vascular diseases. However, detrimental side effects and low efficacy hinder their use in clinical practice. Members of the corticotropin-releasing hormone (CRH) family, which comprises CRH, urocortin I-III, and CRH receptors (CRHR) 1 and 2, are broadly expressed in the brain and peripheral tissues, including the intestine and cardiovascular system. The CRH family regulates stress-related responses through the hypothalamic-pituitary-adrenal axis. Therapeutic agents that target CRH family members offer a new approach to the treatment of various gastrointestinal disorders, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and colorectal cancer. Since the discovery that CRHR 2 has anti-angiogenic activity during postnatal development in mice, studies have focused on the role of the CRH system in the modulation of blood vessel formation and cardiovascular function. This review will outline the basic biological functions of the CRH family members and the implications for the development of novel anti-angiogenic therapies.

Vascular endothelial growth factor and endothelin-1 levels in normal pregnant women and pregnant women with pre-eclampsia

The aim of the study was to estimate the levels of vascular endothelial growth factor (VEGF) and endothelin-1 (ET-1) in maternal serum from normal pregnant women and women with pre-eclampsia. Serum concentrations of VEGF and ET-1 were measured in maternal blood in control group (n = 40) and in pregnancies complicated by pre-eclampsia (n = 40). Results showed that maternal VEGF levels were significantly raised in women with pre-eclampsia (p < 0.001). ET-1 concentration was not significantly different among women with pre-eclampsia compared with that in the control group. It was concluded that an increase in serum VEGF level was demonstrated in pre-eclampsia, suggesting that VEGF is involved in pathogenesis of pre-eclampsia. Further studies are needed to determine the serum concentrations of VEGF in pregnant women before the development of pre-eclampsia.

Effects of vascular endothelial growth factor on endothelin-1 production by human lung microvascular endothelial cells in vitro

AIMS

Increased endothelin-1 (ET-1) is a hallmark of pulmonary arterial hypertension (PAH), and contributes to its pathogenesis. The factors controlling ET-1 in PAH are poorly understood. Combined with other stimuli, vascular endothelial growth factor (VEGF) blockade results in PAH-like lesions in animal models, and has been associated with PAH in humans. The effects of VEGF on ET-1 production by human lung blood microvascular endothelial cells (HMVEC-LBl) are unknown.

MAIN METHODS

We exposed HMVEC-LBl in-vitro to human VEGF-121 (40 ng/mL) in serum-free medium for 7h, in the absence or presence of the VEGF receptor antagonist, SU5416 (3 and 10 μM). ET-1 production was measured in the supernatant. Phosphorylation of VEGF receptor 2 (VEGFR2) was measured by Western blotting after exposure to VEGF without or with SU5416 for 5 and 10 min.

KEY FINDINGS

VEGF effectively caused VEGFR2 phosphorylation, which was blocked by SU5416. VEGF decreased ET-1 production by at least 29%. In the absence of VEGF, SU5416 increased ET-1 production, by 16% at 10 μM, and SU5416 was able to completely abolish the VEGF effect on ET-1 production.

SIGNIFICANCE

VEGF may promote vascular health by decreasing ET-1 production in HVMEC-LBl. Blockade of VEGF signaling by SU5416 increases ET-1 levels. The role of VEGF in modulating endothelin production in PAH deserves further study.

Podocyte-specific VEGF-a gain of function induces nodular glomerulosclerosis in eNOS null mice

VEGF-A and nitric oxide are essential for glomerular filtration barrier homeostasis and are dysregulated in diabetic nephropathy. Here, we examined the effect of excess podocyte VEGF-A on the renal phenotype of endothelial nitric oxide synthase (eNOS) knockout mice. Podocyte-specific VEGF(164) gain of function in eNOS(-/-) mice resulted in nodular glomerulosclerosis, mesangiolysis, microaneurysms, and arteriolar hyalinosis associated with massive proteinuria and renal failure in the absence of diabetic milieu or hypertension. In contrast, podocyte-specific VEGF(164) gain of function in wild-type mice resulted in less pronounced albuminuria and increased creatinine clearance. Transmission electron microscopy revealed glomerular basement membrane thickening and podocyte effacement in eNOS(-/-) mice with podocyte-specific VEGF(164) gain of function. Furthermore, glomerular nodules overexpressed collagen IV and laminin extensively. Biotin-switch and proximity ligation assays demonstrated that podocyte-specific VEGF(164) gain of function decreased glomerular S-nitrosylation of laminin in eNOS(-/-) mice. In addition, treatment with VEGF-A decreased S-nitrosylated laminin in cultured podocytes. Collectively, these data indicate that excess glomerular VEGF-A and eNOS deficiency is necessary and sufficient to induce Kimmelstiel-Wilson-like nodular glomerulosclerosis in mice through a process that involves deposition of laminin and collagen IV and de-nitrosylation of laminin.

Angiotensin converting enzyme insertion/deletion (I/D) (rs4646994) and Vegf polymorphism (+405G/C; rs2010963) in type II diabetic patients: Association with the risk of coronary artery disease

HYPOTHESIS

Little is known about the concomitant presence of the angiotensin-converting enzyme (ACE) (rs4646994) D allele and vascular endothelial growth factor(VEGF) (+405G/C; rs2010963) G allele on the susceptibility of coronary artery disease (CAD). Here we examined the hypothesis that ACE-D and VEGF-G alleles act synergistically to increase the severity of CAD in patients with type II diabetes mellitus (T2DM).

MATERIALS AND METHODS

The VEGF (rs2010963) and ACE (rs4646994) genotypes were detected by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) and PCR, respectively in 510 T2DM patients undergoing their first coronary angiography. Diabetic patients were classified as T2DM patients with and without CAD (control).

RESULTS

The crude odds ratio (OR) for the presence of CAD in ID+DD and D allele carriers were 1.98 (p=0.01) and 1.55 (p=0.001), respectively. Also, adjusted ORs in the presence of normolipidemia and the absence of history of hypertension for the risk of CAD in the either ACE(rs4646994) D allele or VGEF(rs2010963)-G alleles were 2.08 (p=0.004) and 1.75 (p=0.024), respectively. In addition, the concomitant presence of the ACE-D and VEGF-G alleles increased the risk of CAD 2.25-fold (p=0.043).

CONCLUSION

Our results indicated that ACE(rs4646994)-D allele alone and in the presence of VEGF(rs2010963)-G allele can be an important independent risk factor for susceptibility of CAD in T2DM patients even after correcting for conventional risk factors in a population of Iran.

Blood pressure regulation V: in vivo mechanical properties of precapillary vessels as affected by long-term pressure loading and unloading

Recent studies are reviewed, concerning the in vivo wall stiffness of arteries and arterioles in healthy humans, and how these properties adapt to iterative increments or sustained reductions in local intravascular pressure. A novel technique was used, by which arterial and arteriolar stiffness was determined as changes in arterial diameter and flow, respectively, during graded increments in distending pressure in the blood vessels of an arm or a leg. Pressure-induced increases in diameter and flow were smaller in the lower leg than in the arm, indicating greater stiffness in the arteries/arterioles of the leg. A 5-week period of intermittent intravascular pressure elevations in one arm reduced pressure distension and pressure-induced flow in the brachial artery by about 50 %. Conversely, prolonged reduction of arterial/arteriolar pressure in the lower body by 5 weeks of sustained horizontal bedrest, induced threefold increases of the pressure-distension and pressure-flow responses in a tibial artery. Thus, the wall stiffness of arteries and arterioles are plastic properties that readily adapt to changes in the prevailing local intravascular pressure. The discussion concerns mechanisms underlying changes in local arterial/arteriolar stiffness as well as whether stiffness is altered by changes in myogenic tone and/or wall structure. As regards implications, regulation of local arterial/arteriolar stiffness may facilitate control of arterial pressure in erect posture and conditions of exaggerated intravascular pressure gradients. That increased intravascular pressure leads to increased arteriolar wall stiffness also supports the notion that local pressure loading may constitute a prime mover in the development of vascular changes in hypertension.

Angiogenic response to passive movement and active exercise in individuals with peripheral arterial disease

Peripheral arterial disease (PAD) is caused by atherosclerosis and is associated with microcirculatory impairments in skeletal muscle. The present study evaluated the angiogenic response to exercise and passive movement in skeletal muscle of PAD patients compared with healthy control subjects. Twenty-one PAD patients and 17 aged control subjects were randomly assigned to either a passive movement or an active exercise study. Interstitial fluid microdialysate and tissue samples were obtained from the thigh skeletal muscle. Muscle dialysate vascular endothelial growth factor (VEGF) levels were modestly increased in response to either passive movement or active exercise in both subject groups. The basal muscle dialysate level of the angiostatic factor thrombospondin-1 protein was markedly higher (P < 0.05) in PAD patients compared with the control subjects, whereas soluble VEGF receptor-1 dialysate levels were similar in the two groups. The basal VEGF protein content in the muscle tissue samples was ∼27% lower (P < 0.05) in the PAD patients compared with the control subjects. Analysis of mRNA expression for a range of angiogenic and angiostatic factors revealed a modest change with active exercise and passive movement in both groups, except for an increase (P < 0.05) in the ratio of angiopoietin-2 to angiopoietin-1 mRNA in the PAD group with both interventions. PAD patients and aged individuals showed a similar limited angiogenic response to active exercise and passive movement. The limited increase in muscle extracellular VEGF combined with an elevated basal level of thrombospondin-1 in muscle extracellular fluid of PAD patients may restrict capillary growth in these patients.

Aortopulmonary collateral flow in cystic fibrosis assessed with phase-contrast MRI

BACKGROUND

Cystic fibrosis (CF) is a common genetic disease in Caucasians. Chronic pulmonary disease with progressive destruction of the pulmonary parenchyma is two of the major morbidities, but the relationship between clinical severity of CF and aortopulmonary collateral blood flow has not been assessed.

OBJECTIVE

The purpose of this study is to measure changes in aortopulmonary collateral blood flow by phase-contrast magnetic resonance imaging (MRI) in children with CF across the spectrum of disease severity as measured by the forced expiratory volume in one second as percent predicted value (FEV1% predicted).

MATERIALS AND METHODS

Sixteen patients with CF were prospectively evaluated. Eight were classified as having mild CF lung disease (FEV1 ≥80% predicted) and eight were classified as having moderate to severe CF lung disease (FEV1 <80% predicted). Seventeen age- and gender-matched non-CF subjects without cardiac or lung disease served as controls. Phase-contrast flow was measured at the ascending aorta, main pulmonary artery and both pulmonary arteries. Aortopulmonary collateral blood flow was calculated for each subject. The relationship between collateral flow and FEV1% predicted was modeled using nonparametric regression. Group differences were assessed by analysis of variance.

RESULTS

Aortopulmonary collateral blood flow began to increase as FEV1% predicted in subjects with CF fell below 101.5% with significant further increase in the aortopulmonary collateral blood flow in the subjects with CF with moderate to severe lung disease compared to controls (0.89 vs. 0.20 L/min, P < 0.0001). Aortopulmonary collateral blood flow correlated negatively with FEV1% predicted (r=0.70, P = 0.0050) confirming its relationship to this established marker of disease severity. There was no statistically significant difference in results obtained from two independent observers.

CONCLUSION

These preliminary findings suggest that phase-contrast MRI can be performed reliably with consistent results and without interobserver variability. While the aortopulmonary collateral blood flow is within the normal range in subjects with mild CF disease, it begins to increase even when lung function is still in the normal range. A significant increase in the aortopulmonary collateral blood flow compared to controls is measured in patients with moderate to severe CF lung disease. The studies support the notion that aortopulmonary collateral blood flow may serve as a novel and sensitive biomarker of early pulmonary disease in cystic fibrosis.

Serum Containing Tao-Hong-Si-Wu Decoction Induces Human Endothelial Cell VEGF Production via PI3K/Akt-eNOS Signaling

Tao-Hong-Si-Wu decoction (TSD) is a famous traditional Chinese medicine (TCM) and widely used for ischemic disease in China. TSD medicated serum was prepared after oral administration of TSD (1.6 g/kg) twice a day for 3 days in rats. TSD medicated serum induced human umbilical vein endothelial cells (HUVECs) proliferation, VEGF secretion, and nitric oxide (NO) production. These promoted effects of TSD were partly inhibited by treatment with PI3K inhibitor (LY294002) or eNOS inhibitor (L-NAME), respectively, and completely inhibited by treatment with LY294002 and L-NAME simultaneously. Western blot analysis findings further indicated that TSD medicated serum upregulated p-Akt and p-eNOS expressions, which were significantly inhibited by LY294002 or L-NAME and completely inhibited by both LY294002 and L-NAME; these results indicated that TSD medicated serum induced HUVECs VEGF expression via PI3K/Akt-eNOS signaling. TSD medicated serum contains hydroxysafflor yellow A, ferulic acid, and ligustilide detected by UPLC with standards, so these effect of TSD medicated serum may be associated with these three active compounds absorbed in serum.

VEGF and podocytes in diabetic nephropathy

Vascular endothelial growth factor-A (VEGF-A) is a protein secreted by podocytes that is necessary for survival of endothelial cells, podocytes, and mesangial cells. VEGF-A regulates slit-diaphragm signaling and podocyte shape via VEGF-receptor 2-nephrin-nck-actin interactions. Chronic hyperglycemia-induced excess podocyte VEGF-A and low endothelial nitric oxide drive the development and the progression of diabetic nephropathy. The abnormal cross-talk between VEGF-A and nitric oxide pathways is fueled by the diabetic milieu, resulting in increased oxidative stress. Recent findings on these pathogenic molecular mechanisms provide new potential targets for therapy for diabetic renal disease.

Differential effects of pharmacological HIF preconditioning of donors versus recipients in rat cardiac allografts

Ischemia-reperfusion injury (IRI) induces hypoxia-inducible factor-1 (HIF-1) in the myocardium, but the consequences remain elusive. We investigated HIF-1 activation during cold and warm ischemia and IRI in rat hearts and cardiac syngrafts. We also tested the effect of HIF-α stabilizing prolyl hydroxylase inhibitor (FG-4497) on IRI or allograft survival. Ex vivo ischemia of the heart increased HIF-1α expression in a time- and temperature-dependent fashion. Immunohistochemistry localized HIF-1α to all cardiac cell types. After reperfusion, HIF-1α immunoreactivity persisted in smooth muscle cells and cardiomyocytes in the areas with IRI. This was accompanied with a transient induction of protective HIF-1 downstream genes. Donor FG-4497 pretreatment for 4 h enhanced IRI in cardiac allografts as evidenced by an increase in cardiac troponin T release, cardiomyocyte apoptosis, and activation of innate immunity. Recipient FG-4497 pretreatment for 4 h decreased infiltration of ED1(+) macrophages, and mildly improved the long-term allograft survival. In syngrafts donor FG-4497 pretreatment increased activation of innate immunity, but did not induce myocardial damage. We conclude that the HIF-1 pathway is activated in heart transplants. We suggest that pharmacological HIF-α preconditioning of cardiac allografts donors would not lead to clinical benefit, while in recipients it may result in antiinflammatory effects and prolonged allograft survival.

Protective effects of astaxanthin on capillary regression in atrophied soleus muscle of rats

AIM

The capillary regression in skeletal muscles associated with a chronic decrease in activity is related to a dysfunction of endocapillary cells induced by over-expression of oxidative stress. We hypothesized that treatment with astaxanthin, an antioxidant, would attenuate the oxidative stress induced by decreased skeletal muscle use, and that this attenuation would prevent the associated capillary regression. The purpose of the present study was to investigate the antioxidant and preventive effects of astaxanthin on capillary regression in the soleus muscle during hindlimb unloading.

METHODS

Twenty-four adult male Wistar rats were assigned randomly either to a control, control plus astaxanthin treatment, hindlimb unloaded or hindlimb unloaded plus astaxanthin treatment group for 7 days.

RESULTS

Hindlimb unloading resulted in a decrease in mean soleus absolute weight, capillary number, volume and luminal diameter. The accumulation of reactive oxygen species and the over-expression of superoxide dismutase (SOD-1), a decrease in the levels of vascular endothelial growth factor (VEGF) and its receptors, an inhibition of the angiopoietin pathway and an increase of thrombospondin-1 (TSP-1), as an anti-angiogenic factor were showed. Administration of astaxanthin attenuated the changes in SOD-1 and VEGF, up-regulated the angiogenic factors and reduced the capillary regression in the soleus of hindlimb unloaded rats. In addition, the VEGF-to-TSP1 ratio was higher in the astaxanthin treated groups than in the control and HU groups.

CONCLUSION

These results suggest that astaxanthin may be an effective treatment to counter the detrimental effects of a chronic decrease in skeletal muscle use on the capillary network and associated angiogenic pathways.

Cardiovascular complications associated with novel angiogenesis inhibitors: emerging evidence and evolving perspectives

Novel cancer therapies targeting tumor angiogenesis have revolutionized treatment options in a variety of tumors. Specifically, VEGF signaling pathway (VSP) inhibitors have been introduced into clinical practice at a rapid pace over the last decade. It is becoming increasingly clear that VSP inhibitors can cause cardiovascular toxicities including hypertension, thrombosis, and heart failure. This review highlights these toxicities and proposes several strategies in their prevention and treatment. However, we recognize the dearth of data in this area and advocate a multi-disciplinary approach involving cardiologists and oncologists, as well as clinical and translational studies, in understanding and treating VSP-inhibitor associated toxicities.

S100A1 deficiency impairs postischemic angiogenesis via compromised proangiogenic endothelial cell function and nitric oxide synthase regulation

RATIONALE

Mice lacking the EF-hand Ca2+ sensor S100A1 display endothelial dysfunction because of distorted Ca2+ -activated nitric oxide (NO) generation.

OBJECTIVE

To determine the pathophysiological role of S100A1 in endothelial cell (EC) function in experimental ischemic revascularization.

METHODS AND RESULTS

Patients with chronic critical limb ischemia showed almost complete loss of S100A1 expression in hypoxic tissue. Ensuing studies in S100A1 knockout (SKO) mice subjected to femoral artery resection unveiled insufficient perfusion recovery and high rates of autoamputation. Defective in vivo angiogenesis prompted cellular studies in SKO ECs and human ECs, with small interfering RNA-mediated S100A1 knockdown demonstrating impaired in vitro and in vivo proangiogenic properties (proliferation, migration, tube formation) and attenuated vascular endothelial growth factor (VEGF)-stimulated and hypoxia-stimulated endothelial NO synthase (eNOS) activity. Mechanistically, S100A1 deficiency compromised eNOS activity in ECs by interrupted stimulatory S100A1/eNOS interaction and protein kinase C hyperactivation that resulted in inhibitory eNOS phosphorylation and enhanced VEGF receptor-2 degradation with attenuated VEGF signaling. Ischemic SKO tissue recapitulated the same molecular abnormalities with insufficient in vivo NO generation. Unresolved ischemia entailed excessive VEGF accumulation in SKO mice with aggravated VEGF receptor-2 degradation and blunted in vivo signaling through the proangiogenic phosphoinositide-3-kinase/Akt/eNOS cascade. The NO supplementation strategies rescued defective angiogenesis and salvaged limbs in SKO mice after femoral artery resection.

CONCLUSIONS

Our study shows for the first time downregulation of S100A1 expression in patients with critical limb ischemia and identifies S100A1 as critical for EC function in postnatal ischemic angiogenesis. These findings link its pathological plasticity in critical limb ischemia to impaired neovascularization, prompting further studies to probe the microvascular therapeutic potential of S100A1.