The effect of microencapsulated watermelon rind (Citrullus lanatus) and beetroot (Beta vulgaris L.) ingestion on ischemia/reperfusion-induced endothelial dysfunction: a randomised clinical trial

Endothelial dysfunction is commonly associated with a cardiovascular event, such as myocardial infarction. Myocardial infarction is marked by an ischemia/reperfusion (IR) phenomenon associated with endothelial dysfunction, contributing even more to future cardiovascular events. Although the supplementation with L-citrulline and nitrate from watermelon and beetroot have been used to improve vascular function, the effect of microencapsulated watermelon rind (WR) or its co-ingestion with beetroot (WR + B) on endothelial IR injury has not been addressed. Therefore, this study aimed to investigate the effect of a single dose of WR and WR + B on IR-induced macro-and microvascular dysfunction. In a randomized, crossover, placebo-controlled study, 12 volunteers underwent macro (flow-mediated dilation) and microvascular (muscle oxygen saturation) assessment and blood collection (to measure L-citrulline, L-arginine, nitrate and nitrite) before and after 20 min of blood occlusion in WR, WR + B and placebo conditions. Prolonged ischemia induced endothelial dysfunction in the macro but not in the microvasculature. The WR and WR + B supplementation significantly restored FMD after IR injury compared to the placebo (p < 0.05). However, there was no significant difference between WR and WR + B in the macrovascular function (p > 0.05). Plasma L-citrulline, L-arginine, nitrate, and nitrite significantly increased (p > 0.05) after WR and WR + B supplementation compared to the placebo. A single dose of WR and WR + B effectively minimizes IR-induced macrovascular endothelial dysfunction in healthy individuals. Beetroot co-ingestion with watermelon did not provide an additional effect of endothelial dysfunction induced by IR (NCT04781595, March 4, 2021).

Growth Hormone Releasing Hormone in Endothelial Barrier Function

Growth hormone releasing hormone (GHRH) is the integral regulator of the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis. It exerts mitogenic effects in a plethora of progressive cancers. Recent evidence suggests the emerging role of that 44-amino acid (aa) neuropeptide in lung endothelial barrier function (EBF), which will be discussed herein.

Actigraphy-Derived Sleep Efficiency Is Associated With Endothelial Function in Men and Women With Untreated Hypertension

BACKGROUND

Poor sleep quality is increasingly recognized as an important and potentially modifiable risk factor for cardiovascular disease (CVD). Impaired endothelial function may be 1 mechanism underlying the association between poor sleep and CVD risk. The present study examined the relationship between objective measures of sleep quality and endothelial function in a sample of untreated hypertensive adults.

METHODS

Participants were 127 men (N = 74) and women (N = 53), including 55 African Americans and 72 White Americans, aged 40-60 years (mean age, 45.3 ± 8.5 years), with untreated hypertension (systolic blood pressure 130-159 mm Hg and/or diastolic blood pressure 85-99 mm Hg). Noninvasive brachial artery flow-mediated dilation (FMD) was assessed by ultrasound. Sleep parameters, including sleep efficiency (SE), total sleep time (TST), and subjective sleep quality, were assessed over 7 consecutive days by wrist actigraphy.

RESULTS

Participants averaged 7.76 ± 1 hours in bed, with an average SE of 78 ± 9%, and TST of 6 ± 1 hours. Brachial FMD averaged 3.5 ± 3.1%. In multivariate analyses controlling for sex, race, body mass index, clinic blood pressure, income, smoking, alcohol use, and baseline arterial diameter, SE was positively associated with FMD (β = 0.28, P = 0.012). Subjective sleep quality (β = -0.04, P = 0.63) and TST (β = -0.11, P = 0.25) were unrelated to FMD.

CONCLUSIONS

Poor sleep as indicated by low SE was associated with impaired FMD. These findings for SE are consistent with previous observations of other measures implicating poor sleep as a CVD risk factor. Interventions that improve sleep may also help lower CVD risk.

The effect of dietary nitrate and vitamin C on endothelial function, oxidative stress and blood lipids in untreated hypercholesterolemic subjects: A randomized double-blind crossover study

BACKGROUND

Vitamin C may enhance nitric oxide (NO) production through stepwise reduction of dietary nitrate (NO₃) to nitrite (NO₂) to NO. The combined effect of vitamin C and NO₃ supplementation is relatively unexplored in untreated hypercholesterolemia.

AIMS

We aimed to examine whether co-administration of vitamin C and nitrate for 4-weeks would improve endothelial function (primary outcome), plasma NO metabolites, oxidative stress, and blood lipids (secondary outcomes).

METHODS

Subjects 50-70 years of age with low density lipoprotein (LDL) > 130 mg/dL and RHI ≤2 were enrolled in this randomized double-blind crossover study. Subjects were assigned to two 4-week supplementation treatments starting with 70 ml of concentrated beetroot juice (CBJ) with 1000 mg of vitamin C (NC) or CBJ with matched placebo (N), then switched to alternate treatment following 2-week washout. The change in reactive hyperemia index (RHI), sum of plasma NO metabolites (NO₂ + NO₃ (NOx)), oxidized LDL (oxLDL), and serum lipids were assessed at baseline and at 4-weeks of each treatment period.

RESULTS

Eighteen subjects (11M:7F) completed all study visits. No significant treatment differences were observed in RHI change (N: 0.21 ± 0.12; NC: 0.20 ± 0.17; p = 0.99). Secondary analysis revealed that a subgroup of NC subjects who started with a baseline RHI of <1.67 (threshold value for ED) had greater improvements in RHI compared to subjects with RHI >1.67 (1.23 ± 0.15 to 1.96 ± 0.19; n = 8 vs. 1.75 ± 0.11 to 1.43 ± 0.10; n = 8; p = 0.02). Compared to N, NC experienced a significant increase in plasma NOx (N: 94.2 ± 15.5 μmol/L; NC: 128.7 ± 29.1 μmol/L; p = 0.01). Although there was no significant difference in oxLDL change between treatments (N: -1.08 ± 9.8 U/L; NC: -6.07 ± 9.14 U/L; p = 0.19), NC elicited significant reductions in LDL (N: 2.2 ± 2; NC: -10.7 ± 23; p = 0.049), triglycerides (N: 14.6 ± 43; NC: -43.7 ± 45; p = 0.03), and no change in serum high density lipoprotein. Within treatment group comparisons showed that only NC reduced oxLDL significantly from baseline to 4 weeks (p = 0.01).

CONCLUSIONS

No between intervention differences were observed in RHI. RHI only improved in NC subjects with ED at intervention baseline. Four weeks of NC enriched the NO pool and promoted reduction of blood lipids and oxidative stress in subjects with hypercholesterolemia. These preliminary findings highlight a supplementation strategy that may reduce the progression of atherosclerotic disease and deserves further attention in studies using flow mediated dilation methods.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04283630).

The endothelium, a key actor in organ development and hPSC-derived organoid vascularization

Over the last 4 decades, cell culture techniques have evolved towards the creation of in vitro multicellular entities that incorporate the three-dimensional complexity of in vivo tissues and organs. As a result, stem cells and adult progenitor cells have been used to derive self-organized 3D cell aggregates that mimic the morphological and functional traits of organs in vitro. These so-called organoids were first generated from primary animal and human tissues, then human pluripotent stem cells (hPSCs) arose as a new tool for organoid generation. Due to their self-renewal capacity and differentiation potential, hPSCs are an unlimited source of cells used for organoids. Today, hPSC-derived small intestinal, kidney, brain, liver, and pancreas organoids, among others, have been produced and are promising in vitro human models for diverse applications, including fundamental research, drug development and regenerative medicine. However, achieving in vivo-like organ complexity and maturation in vitro remains a challenge. Current hPSC-derived organoids are often limited in size and developmental state, resembling embryonic or fetal organs rather than adult organs. The use of endothelial cells to vascularize hPSC-derived organoids may represent a key to ensuring oxygen and nutrient distribution in large organoids, thus contributing to the maturation of adult-like organoids through paracrine signaling.Here, we review the current state of the art regarding vascularized hPSC-derived organoids (vhPSC-Orgs). We analyze the progress achieved in the generation of organoids derived from the three primary germ layers (endoderm, mesoderm and ectoderm) exemplified by the pancreas, liver, kidneys and brain. Special attention will be given to the role of the endothelium in the organogenesis of the aforementioned organs, the sources of endothelial cells employed in vhPSC-Org protocols and the remaining challenges preventing the creation of ex vivo functional and vascularized organs.

Rab5c-mediated endocytic trafficking regulates hematopoietic stem and progenitor cell development via Notch and AKT signaling

It is well known that various developmental signals play diverse roles in hematopoietic stem and progenitor cell (HSPC) production; however, how these signaling pathways are orchestrated remains incompletely understood. Here, we report that Rab5c is essential for HSPC specification by endocytic trafficking of Notch and AKT signaling in zebrafish embryos. Rab5c deficiency leads to defects in HSPC production. Mechanistically, Rab5c regulates hemogenic endothelium (HE) specification by endocytic trafficking of Notch ligands and receptor. We further show that the interaction between Rab5c and Appl1 in the endosome is required for the survival of HE in the ventral wall of the dorsal aorta through AKT signaling. Interestingly, Rab5c overactivation can also lead to defects in HSPC production, which is attributed to excessive endolysosomal trafficking inducing Notch signaling defect. Taken together, our findings establish a previously unrecognized role of Rab5c-mediated endocytic trafficking in HSPC development and provide new insights into how spatiotemporal signals are orchestrated to accurately execute cell fate transition.

Cell-autonomous Notch signaling regulated by the membrane trafficking protein Rab5c plays an instructive role in hematopoietic stem and progenitor cell specification, while the AKT signaling seems to provide a permissive signal to maintain hemogenic endothelium survival.

Pharmacokinetics of maslinic and oleanolic acids from olive oil - Effects on endothelial function in healthy adults. A randomized, controlled, dose-response study

To date, pharmacokinetics of maslinic (MA) and oleanolic (OA) acids, at normal dietary intakes in humans, have not been evaluated, and data concerning their bioactive effects are scarce. We assessed MA and OA pharmacokinetics after ingestion of olive oils (OOs) with high and low triterpenic acid contents, and specifically the effect of triterpenes on endothelial function. We performed a double-blind, dose-response, randomized, cross-over nutritional intervention in healthy adults, and observed that MA and OA increased in biological fluids in a dose-dependent manner. MA bioavailability was greater than that of OA, and consumption of pentacyclic triterpenes was associated with improved endothelial function. To the best of our knowledge, this is the first time MA pharmacokinetics, and effects on endothelial function in vivo, have been reported in humans.

Galectin-1-driven T cell exclusion in the tumor endothelium promotes immunotherapy resistance

Immune checkpoint inhibitors (ICIs), although promising, have variable benefit in head and neck cancer (HNC). We noted that tumor galectin-1 (Gal1) levels were inversely correlated with treatment response and survival in patients with HNC who were treated with ICIs. Using multiple HNC mouse models, we show that tumor-secreted Gal1 mediates immune evasion by preventing T cell migration into the tumor. Mechanistically, Gal1 reprograms the tumor endothelium to upregulate cell-surface programmed death ligand 1 (PD-L1) and galectin-9. Using genetic and pharmacological approaches, we show that Gal1 blockade increases intratumoral T cell infiltration, leading to a better response to anti-PD1 therapy with or without radiotherapy. Our study reveals the function of Gal1 in transforming the tumor endothelium into an immune-suppressive barrier and that its inhibition synergizes with ICIs.

Influence of Local Myocardial Infarction on Endothelial Function, Neointimal Progression, and Inflammation in Target and Non-Target Vascular Territories in a Porcine Model of Acute Myocardial Infarction

BACKGROUND

Patients with acute myocardial infarction (AMI) have worse clinical outcomes than those with stable coronary artery disease despite revascularization. Non-culprit lesions of AMI also involve more adverse cardiovascular events. This study aimed to investigate the influence of AMI on endothelial function, neointimal progression, and inflammation in target and non-target vessels.

METHODS

In castrated male pigs, AMI was induced by balloon occlusion and reperfusion into the left anterior descending artery (LAD). Everolimus-eluting stents (EES) were implanted in the LAD and left circumflex (LCX) artery 2 days after AMI induction. In the control group, EES were implanted in the LAD and LCX in a similar fashion without AMI induction. Endothelial function was assessed using acetylcholine infusion before enrollment, after the AMI or sham operation, and at 1 month follow-up. A histological examination was conducted 1 month after stenting.

RESULTS

A total of 10 pigs implanted with 20 EES in the LAD and LCX were included. Significant paradoxical vasoconstriction was assessed after acetylcholine challenge in the AMI group compared with the control group. In the histologic analysis, the AMI group showed a larger neointimal area and larger area of stenosis than the control group after EES implantation. Peri-strut inflammation and fibrin formation were significant in the AMI group without differences in injury score. The non-target vessel of the AMI also showed similar findings to the target vessel compared with the control group.

CONCLUSION

In the pig model, AMI events induced endothelial dysfunction, inflammation, and neointimal progression in the target and non-target vessels.

Endothelium structure and function in kidney health and disease

The kidney harbours different types of endothelia, each with specific structural and functional characteristics. The glomerular endothelium, which is highly fenestrated and covered by a rich glycocalyx, participates in the sieving properties of the glomerular filtration barrier and in the maintenance of podocyte structure. The microvascular endothelium in peritubular capillaries, which is also fenestrated, transports reabsorbed components and participates in epithelial cell function. The endothelium of large and small vessels supports the renal vasculature. These renal endothelia are protected by regulators of thrombosis, inflammation and complement, but endothelial injury (for example, induced by toxins, antibodies, immune cells or inflammatory cytokines) or defects in factors that provide endothelial protection (for example, regulators of complement or angiogenesis) can lead to acute or chronic renal injury. Moreover, renal endothelial cells can transition towards a mesenchymal phenotype, favouring renal fibrosis and the development of chronic kidney disease. Thus, the renal endothelium is both a target and a driver of kidney and systemic cardiovascular complications. Emerging therapeutic strategies that target the renal endothelium may lead to improved outcomes for both rare and common renal diseases.

The biomolecular interactions between endothelium and bone cells: an overview

Bone turnover is a complex set of different molecules pathways and it is strictly connected with bone vasculature. It includes every bone process concerning bone modelling and remodelling such us skeletal growth and healing process. A fundamental component of this bone architecture is played by the endothelium, that acts in a paracrine fashion on other bone stromal cells via humoral factors, growth factors and chemokines/cytokines. The alteration of those biochemical interactions between endothelium, vasculature and bone tissue may cause various pathological manifestations. Understanding the bases of the interaction between those different pathways could provide novel therapeutic strate¬gies for bone disease. The Authors present an updated overview of the most common communication biomolecules between bone cells and endothelium and their interactions both in healthy and pathological conditions. Furthermore, focusing on gene and related therapies, possible future therapeutic strategies for bone vasculature/metabolic diseases are presented.

Maternal cardiovascular and endothelial function from first trimester to postpartum

Objective

To explore noninvasively the complex interactions of the maternal hemodynamic system throughout pregnancy and the resulting after-effect six weeks postpartum.

Methods

Eighteen women were tested beginning at the 12^th week of gestation at six time-points throughout pregnancy and six weeks postpartum. Heart rate, heart rate variability, blood pressure, pulse transit time (PTT), respiration, and baroreceptor sensitivity were analyzed in resting conditions. Additionally, hemoglobin, asymmetric and symmetric dimethylarginine and Endothelin (ET-1) were obtained.

Results

Heart rate and sympathovagal balance favoring sympathetic drive increased, the vagal tone and the baroreflex sensitivity decreased during pregnancy. Relative sympathetic drive (sympathovagal balance) reached a maximum at 6 weeks postpartum whereas the other variables did not differ compared to first trimester levels. Postpartum diastolic blood pressure was higher compared to first and second trimester. Pulse transit time and endothelial markers showed no difference throughout gestation. However, opposing variables PTT and asymmetric dimethylarginine (ADMA) were both higher six weeks postpartum.

Conclusions

The sympathetic up regulation throughout pregnancy goes hand in hand with a decreased baroreflex sensitivity. In the postpartum period, the autonomic nervous system, biochemical endothelial reactions and PTT show significant and opposing changes compared to pregnancy findings, indicating the complex aftermath of the increase of blood volume, the changes in perfusion strategies and blood pressure regulation that occur in pregnancy.

Self-Condensation Culture Enables Vascularization of Tissue Fragments for Efficient Therapeutic Transplantation

Clinical transplantation of tissue fragments, including islets, faces a critical challenge because of a lack of effective strategies that ensure efficient engraftment through the timely integration of vascular networks. We recently developed a complex organoid engineering method by "self-condensation" culture based on mesenchymal cell-dependent contraction, thereby enabling dissociated heterotypic lineages including endothelial cells to self-organize in a spatiotemporal manner. Here, we report the successful adaptation of this method for generating complex tissues from diverse tissue fragments derived from various organs, including pancreatic islets. The self-condensation of human and mouse islets with endothelial cells not only promoted functionalization in culture but also massively improved post-transplant engraftment. Therapeutically, fulminant diabetic mice were more efficiently treated by a vascularized islet transplant compared with the conventional approach. Given the general limitations of post-transplant vascularization associated with 3D tissue-based therapy, our approach offers a promising means of enhancing efficacy in the context of therapeutic tissue transplantation.

HOXB4 Promotes Hemogenic Endothelium Formation without Perturbing Endothelial Cell Development

Generation of hematopoietic stem cells (HSCs) from pluripotent stem cells, in vitro, holds great promise for regenerative therapies. Primarily, this has been achieved in mouse cells by overexpression of the homeotic selector protein HOXB4. The exact cellular stage at which HOXB4 promotes hematopoietic development, in vitro, is not yet known. However, its identification is a prerequisite to unambiguously identify the molecular circuits controlling hematopoiesis, since the activity of HOX proteins is highly cell and context dependent. To identify that stage, we retrovirally expressed HOXB4 in differentiating mouse embryonic stem cells (ESCs). Through the use of Runx1(-/-) ESCs containing a doxycycline-inducible Runx1 coding sequence, we uncovered that HOXB4 promoted the formation of hemogenic endothelium cells without altering endothelial cell development. Whole-transcriptome analysis revealed that its expression mediated the upregulation of transcription of core transcription factors necessary for hematopoiesis, culminating in the formation of blood progenitors upon initiation of Runx1 expression.

NADPH oxidase 4 and endothelial nitric oxide synthase contribute to endothelial dysfunction mediated by histone methylations in metabolic memory

"Metabolic memory" is identified as a phenomenon that transient hyperglycemia can be remembered by vasculature for quite a long term even after reestablishment of normoglycemia. NADPH oxidases (Noxs) and endothelial nitric oxide synthase (eNOS) are important enzymatic sources of reactive oxygen species (ROS) in diabetic vasculature. The aim of this study is to explore the roles of epigenetics and ROS derived from Noxs and eNOS in the metabolic memory. In this study, we demonstrated that vascular ROS was continuously activated in endothelium induced by transient high glucose, as well as sustained vascular endothelial dysfunction. The Nox4 and uncoupled eNOS are the major sources of ROS, while inhibition of Nox4 and eNOS significantly attenuated oxidative stress and almost recovered the endothelial function in metabolic memory. Furthermore, the aberrant histone methylation (H3K4me1, H3K9me2, and H3K9me3) at promoters of Nox4 and eNOS are the main causes for the persistent up-regulation of these two genes. Modifying the histone methylation could reduce the expression levels of Nox4 and eNOS, thus obviously attenuating endothelial dysfunction. These results indicate that histone methylation of Nox4 and eNOS play a key role in metabolic memory and may be the potential intervention targets for metabolic memory.

The Novel Compound Sul-121 Preserves Endothelial Function and Inhibits Progression of Kidney Damage in Type 2 Diabetes Mellitus in Mice

Diabetic nephropathy is still a common complication of type 2 diabetes mellitus (T2DM) and improvement of endothelial dysfunction (ED) and inhibition of reactive oxygen species (ROS) are considered important targets for new therapies. Recently, we developed a new class of compounds (Sul compounds) which inhibit mitochondrial ROS production. Here, we tested the therapeutic effects of Sul-121 on ED and kidney damage in experimental T2DM. Diabetic db/db and lean mice were implanted with osmotic pumps delivering Sul-121 (2.2 mg/kg/day) or vehicle from age 10 to 18 weeks. Albuminuria, blood pressure, endothelial mediated relaxation, renal histology, plasma creatinine, and H2O2 levels were assessed. Sul-121 prevented progression of albuminuria and attenuated kidney damage in db/db, as evidenced by lower glomerular fibronectin expression (~50%), decreased focal glomerular sclerosis score (~40%) and normalization of glomerular size and kidney weight. Further, Sul-121 restored endothelium mediated vasorelaxation through increased production of Nitric Oxide production and normalized plasma H2O2 levels. Sul-121 treatment in lean mice demonstrated no observable major side-effects, indicating that Sul-121 is well tolerated. Our data show that Sul-121 inhibits progression of diabetic kidney damage via a mechanism that involves restoration of endothelial function and attenuation of oxidative stress.

Clinical assessment of endothelial function in patients with chronic obstructive pulmonary disease: a systematic review with meta-analysis

Patients with chronic obstructive pulmonary disease (COPD) have an increased cardiovascular morbidity and mortality. Flow-mediated (FMD) and nitrate-mediated dilatation (NMD) are considered non-invasive methods to assess endothelial function and surrogate markers of subclinical atherosclerosis. We performed a systematic review with meta-analysis and meta-regression to evaluate the impact of COPD on FMD and NMD. Studies were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases. The random-effect method was used to take into account the variability among included studies. A total of eight studies were included in the final analysis, eight with data on FMD (334 COPD patients) and two on NMD (104 COPD patients). Compared to controls, COPD patients show a significantly lower FMD (MD -3.15%; 95% CI -4.89, -1.40; P < 0.001) and NMD (MD -3.53%; 95% CI -7.04, -0.02; P = 0.049). Sensitivity analyses substantially confirms the results. Meta-regression models show that a more severe degree of airway obstruction is associated with a more severe FMD impairment in COPD patients than in controls. Regression analyses confirm that the association between COPD and endothelial dysfunction is independent of baseline smoking status and most traditional cardiovascular risk factors. In conclusion, COPD is significantly and independently associated with endothelial dysfunction. These findings may be useful to plan adequate cardiovascular prevention strategies in this clinical setting, with particular regard to patients with a more severe disease.

Colonization of Neural Allografts by Host Microglial Cells: Relationship to Graft Neovascularization

In order to illuminate functional roles of microglial cells within neural allografts, we have transplanted both whole and microglial and endothelial cell-depleted E14 neural cell suspensions into the intact striatum of Sprague-Dawley rats. Following posttransplantation times of up to 30 days, the intrastrial allografts were analyzed histochemically using the Griffonia simplicifolia B4 isolectin, a marker for both microglia and blood vessels. Our results indicate that both whole and depleted suspension grafts develop identically in terms of neovascularization and microglial colonization. In both types of transplants microglial cells appeared before any blood vessels were apparent. The main phase of graft vascularization occurred between days 7 and 10 posttransplantation and neovascularization was complete by day 21, as revealed by quantitative image analysis. Microglial cells, which were present as ameboid cells during early posttransplantation times, underwent continuing cell differentiation with time that paralleled graft vascular development. By 30 days posttransplantation microglia within the grafts had assumed the fully ramified phenotype characteristic of resting adult microglia. During graft development and vascularization, microglia were often seen in close proximity to ingrowing blood vessels and vascular sprouts. In conclusion, our study has shown that microglial colonization of grafts and graft vascularization occurs independent of donor-derived microglial and endothelial cells, and suggests that the great majority of microglia and vessels within the graft are host derived. We hypothesize that the host microglia invading the allografts play an active role in promoting graft neovascularization.

Gold Nanoparticles Induced Endothelial Leakiness Depends on Particle Size and Endothelial Cell Origin

The endothelium presents a formidable barrier for cancer nanomedicine, as the intravenously introduced nanomedicine needs to leave the blood vessel at the tumor site. Endothelial permeability and retention effect (EPR) is not dependable since it is derived from tumors. Certain nanoparticles with specific characteristics are able to induce micrometer sized gaps between endothelial cells. This effect is called "nanoparticle induced endothelial leakiness" (NanoEL). NanoEL therefore allows the nanotechnology to control access to the tumor even in the absence of any EPR effect. Morever, NanoEL can be applicable to noncancer issues, thereby expanding its usefulness in other subfields of nanomedicine. In this paper, we have shown that Gold (Au) nanoparticles within the range of 10-30 nm are good NanoEL inducing particles. As not all endothelial cells have the same permeability, we found that human mammary endothelial cells and human skin endothelial cells are sensitive to Au induced NanoEL, while human umbilical vein endothelial cells are insensitive, reflective of their innate nature of endothelial permeability. The size window and endothelial cell type sensitivity then helps the nanotechnologists to design future nanoparticles that either exploit NanoEL as a nanotechnology driven strategy to access immature tumors, which do not induce the EPR effect, or avoid NanoEL as a nanotoxic side effect.

Parathyroid Hormone-Related Protein-induced Relaxation of Rat Uterine Arteries: Influence of the Endothelium During Gestation

OBJECTIVE

Parathyroid hormone-related protein (PTHrP) has been reported to relax different vessels. We investigated the influence of both endothelium and gestation on the relaxation of uterine arteries (UA), which supply blood to myometrium and placenta.

METHODS

Small uterine and mesenteric arteries (MA) with (E+) and without endothelium (E-) from day 20 pregnant (P) and nonpregnant (NP) rats were mounted in a myograph, precontracted with phenylephrine (PE) in a physiologic salt solution. Relaxations to PTHrP, acetylcholine, and forskolin were performed and expressed as a percentage of the PE-induced contraction. Blockade of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) was also studied with Nomega-nitro-L-arginine methyl ester (L-NAME) and with charybdotoxin + apamin, respectively.

RESULTS

Gestation significantly increases maximal vasodilating effect of acetylcholine in UA (68% vs 52%, P < .05) and sensitivity to acetylcholine in small mesenteric vessels (P < .05). PTHrP relaxes uterine (maximal relaxation P: 32%, NP: 46%), as well as small MA (P: 68%, NP: 89%), but the maximal relaxation is significantly greater in NP than in P rats (P: 32%, NP: 46%, P < .01) in both vascular beds. In addition, in the UA of P rats, PTHrP only produces relaxation if functional endothelium is present; nevertheless in the absence of endothelium, forskolin still elicits relaxation (65%, P < .01). L-NAME significantly impairs relaxation of E+ UA (P < .05), and so does the association of charybdotoxin + apamin (P < .05). Thus, NO and EDHF contribute largely to this vasorelaxant effect.

CONCLUSION

PTHrP induces a relaxation on UA that is strongly endothelium-dependent during gestation, in contrast to what happens simultaneously in MA.

Polydatin Restores Endothelium-Dependent Relaxation in Rat Aorta Rings Impaired by High Glucose: A Novel Insight into the PPARβ-NO Signaling Pathway

Polydatin, a natural component from Polygonum Cuspidatum, has important therapeutic effects on metabolic syndrome. A novel therapeutic strategy using polydatin to improve vascular function has recently been proposed to treat diabetes-related cardiovascular complications. However, the biological role and molecular basis of polydatin’s action on vascular endothelial cells (VECs)-mediated vasodilatation under diabetes-related hyperglycemia condition remain elusive. The present study aimed to assess the contribution of polydatin in restoring endothelium-dependent relaxation and to determine the details of its underlying mechanism. By measuring endothelium-dependent relaxation, we found that acetylcholine-induced vasodilation was impaired by elevated glucose (55 mmol/L); however, polydatin (1, 3, 10 μmol/L) could restore the relaxation in a dose-dependent manner. Polydatin could also improve the histological damage to endothelial cells in the thoracic aorta. Polydatin’s effects were mediated via promoting the expression of endothelial NO synthase (eNOS), enhancing eNOS activity and decreasing the inducible NOS (iNOS) level, finally resulting in a beneficial increase in NO release, which probably, at least in part, through activation of the PPARβ signaling pathway. The results provided a novel insight into polydatin action, via PPARβ-NO signaling pathways, in restoring endothelial function in high glucose conditions. The results also indicated the potential utility of polydatin to treat diabetes related cardiovascular diseases.

Physical activity in overweight and obese adolescents: systematic review of the effects on physical fitness components and cardiovascular risk factors

BACKGROUND

The increasing prevalence of obesity in the pediatric age range has become a major concern. Studies have investigated the role of physical activity (PA) to prevent obesity in this population. However, previous reviews did not focus on the effects of PA in overweight/obese adolescents on physical fitness and risk factors for cardiovascular disease altogether.

OBJECTIVE

The present systematic review analyzed trials investigating the effect of PA on aerobic capacity, muscle strength, body composition, hemodynamic variables, biochemical markers, and endothelial function in obese/overweight adolescents.

METHODS

PubMed, LILACS, Web of Science, Scopus (including Embase), and SPORTDiscus databases were searched for relevant reports without time limits. Inclusion criteria included studies published in English, with overweight and obese adolescents aged 12-17 years. The review was registered (Number CRD42013004632) on PROSPERO, the International Prospective Register of Systematic Reviews.

RESULTS

The results indicated that PA is associated with significant and beneficial changes in fat percentage, waist circumference, systolic blood pressure, insulin, low-density lipoprotein cholesterol, and total cholesterol, as well as with small non-significant changes in diastolic blood pressure, glucose, and high-density lipoprotein cholesterol.

CONCLUSION

Although limited, results from controlled trials suggest that PA intervention may improve physical fitness and risk factors for cardiovascular disease in adolescents who are overweight or obese.

Soy provides modest benefits on endothelial function without affecting inflammatory biomarkers in adults at cardiometabolic risk

SCOPE

Systemic inflammation, endothelial dysfunction, and oxidative stress are involved in the pathogenesis of the metabolic syndrome (MetS). Epidemiological evidence supports an association between whole soy food consumption and reduced risk of cardiovascular disease (CVD). The objective of this randomized, controlled, cross-over study was to evaluate the effects of soy nut consumption on inflammatory biomarkers and endothelial function and to assess whether isoflavone metabolism to secondary products, equol, and/or O-desmethylangolensin (ODMA), modifies these responses.

METHODS AND RESULTS

n = 17 adults at cardiometabolic risk were randomly assigned to the order of two snack interventions, soy nuts, and macronutrient-matched control snack, for four weeks each, separated by a two week washout period. Outcome measures included biomarkers of inflammation, oxidative stress, and glycemic control (ELISA and clinical analyzers), endothelial function, and arterial stiffness (peripheral arterial tonometry (PAT)), and isoflavone metabolites (LC-MS/MS). Results revealed that consuming soy nuts improved arterial stiffness as assessed by the augmentation index using PAT (p = 0.03), despite lack of improvement in inflammatory biomarkers. Addition of equol and/or ODMA production status as covariates did not significantly change these results.

CONCLUSION

Soy nuts when added to a usual diet for one month provide some benefit on arterial stiffness in adults at cardiometabolic risk.

Endothelium trans differentiated from Wharton's jelly mesenchymal cells promote tissue regeneration: potential role of soluble pro-angiogenic factors

BACKGROUND

Mesenchymal stem cells have a high capacity for trans-differentiation toward many adult cell types, including endothelial cells. Feto-placental tissue, such as Wharton's jelly is a potential source of mesenchymal stem cells with low immunogenic capacity; make them an excellent source of progenitor cells with a potential use for tissue repair. We evaluated whether administration of endothelial cells derived from mesenchymal stem cells isolated from Wharton's jelly (hWMSCs) can accelerate tissue repair in vivo.

METHODS

Mesenchymal stem cells were isolated from human Wharton's jelly by digestion with collagenase type I. Endothelial trans-differentiation was induced for 14 (hWMSC-End14d) and 30 (hWMSC-End30d) days. Cell phenotyping was performed using mesenchymal (CD90, CD73, CD105) and endothelial (Tie-2, KDR, eNOS, ICAM-1) markers. Endothelial trans-differentiation was demonstrated by the expression of endothelial markers and their ability to synthesize nitric oxide (NO).

RESULTS

hWMSCs can be differentiated into adipocytes, osteocytes, chondrocytes and endothelial cells. Moreover, these cells show high expression of CD73, CD90 and CD105 but low expression of endothelial markers prior to differentiation. hWMSCs-End express high levels of endothelial markers at 14 and 30 days of culture, and also they can synthesize NO. Injection of hWMSC-End30d in a mouse model of skin injury significantly accelerated wound healing compared with animals injected with undifferentiated hWMSC or injected with vehicle alone. These effects were also observed in animals that received conditioned media from hWMSC-End30d cultures.

CONCLUSION

These results demonstrate that mesenchymal stem cells isolated from Wharton's jelly can be cultured in vitro and trans-differentiated into endothelial cells. Differentiated hWMSC-End may promote neovascularization and tissue repair in vivo through the secretion of soluble pro-angiogenic factors.

Mediterranean dietary pattern, inflammation and endothelial function: a systematic review and meta-analysis of intervention trials

BACKGROUND

High adherence to a Mediterranean diet (MD) is associated with reduced all-cause and cardiovascular mortality risk. To our knowledge, there is no systematic review and meta-analysis of randomized controlled trials that has compared the effects of an MD on outcomes of endothelial function and inflammation.

METHODS AND RESULTS

Literature search was performed using the electronic databases MEDLINE, EMBASE, and the Cochrane Trial Register. Inclusion criteria were: randomized controlled trials, 19 + years of age, and minimum intervention period of 12 weeks. Study specific weighted mean differences (WMD) were pooled using a random effect model. Seventeen trials including 2300 subjects met the objectives. MD regimens resulted in a significantly more pronounced increase in flow mediated dilatation [WMD: 1.86%, 95% CI 0.23 to 3.48, p = 0.02; I(2) = 43%], and adiponectin [WMD: 1.69 μg/ml, 95% CI 0.27 to 3.11, p = 0.02; I(2) = 78%], while high-sensitive C reactive protein [WMD: -0.98 mg/l, 95% CI -1.48 to -0.49, p < 0.0001; I(2) = 91%], interleukin-6 [WMD: -0.42 pg/ml, 95% CI -0.73 to -0.11, p = 0.008; I(2) = 81%], and intracellular adhesion molecule-1 [WMD: -23.73 ng/ml, 95% CI -41.24 to -6.22 p = 0.008; I(2) = 34%] turned out to be significantly more decreased.

CONCLUSION

The results of the present meta-analysis provide evidence that an MD decreases inflammation and improves endothelial function.

Thymosin beta4 regulates cardiac valve formation via endothelial-mesenchymal transformation in zebrafish embryos

Thymosin beta4 (TB4) has multiple functions in cellular response in processes as diverse as embryonic organ development and the pathogeneses of disease, especially those associated with cardiac coronary vessels. However, the specific roles played by TB4 during heart valve development in vertebrates are largely unknown. Here, we identified a novel function of TB4 in endothelialmesenchymal transformation (EMT) in cardiac valve endocardial cushions in zebrafish. The expressions of thymosin family members in developing zebrafish embryos were determined by whole mount in situ hybridization. Of the thymosin family members only zTB4 was expressed in the developing heart region. Cardiac valve development at 48 h post fertilization was defected in zebrafish TB4 (zTB4) morpholino-injected embryos (morphants). In zTB4 morphants, abnormal linear heart tube development was observed. The expressions of bone morphogenetic protein (BMP) 4, notch1b, and hyaluronic acid synthase (HAS) 2 genes were also markedly reduced in atrio-ventricular canal (AVC). Endocardial cells in the AVC region were stained with anti-Zn5 antibody reactive against Dm-grasp (an EMT marker) to observe EMT in developing cardiac valves in zTB4 morphants. EMT marker expression in valve endothelial cells was confirmed after transfection with TB4 siRNA in the presence of transforming growth factor β (TGFβ) by RT-PCR and immunofluorescent assay. Zn5-positive endocardial AVC cells were not observed in zTB4 morphants, and knockdown of TB4 suppressed TGF-β-induced EMT in ovine valve endothelial cells. Taken together, our results demonstrate that TB4 plays a pivotal role in cardiac valve formation by increasing EMT.1.

Mechanical control of the endothelial barrier

The integrity of the endothelial barrier is controlled by the combined action of chemical and mechanical signaling systems. Permeability-regulating factors signal through small GTPases to regulate the architecture of the cytoskeleton and this has a strong impact on the morphology and stability of VE-cadherin-based cell-cell junctions. The details of how structural and mechanical properties of the actin cytoskeleton influence cell-cell adhesion and how this impacts the dynamic regulation of the endothelial barrier, are beginning to be elucidated. In this review, we discuss the physical and regulatory interactions between the VE-cadherin complex and the actomysoin cytoskeleton, as they are the main determinants of cell-cell adhesion and the mechanical architecture of the cytoskeleton. We discuss, based on recent in vitro data, how a balance between Linear Adherens Junctions, paralleled by cortical actin bundles and Focal Adherens Junctions, connected to radial action bundles, determines endothelial barrier function. We discuss how small GTPases control this balance by regulating the spatial organization and mechanics of actomyosin. We propose a hypothetical model of how biochemical and mechanical signals cooperate locally, at the actomyosin-adhesion interface to open and re-seal the barrier in a rapid and controlled manner.

Running performance at high running velocities is impaired but V'O(₂max) and peripheral endothelial function are preserved in IL-6⁻/⁻ mice

It has been reported that IL-6 knockout mice (IL-6⁻/⁻) possess lower endurance capacity than wild type mice (WT), however the underlying mechanism is poorly understood. The aim of the present work was to examine whether reduced endurance running capacity in IL-6⁻/⁻ mice is linked to impaired maximal oxygen uptake (V'O(₂max)), decreased glucose tolerance, endothelial dysfunction or other mechanisms. Maximal running velocity during incremental running to exhaustion was significantly lower in IL-6⁻/⁻ mice than in WT mice (13.00±0.97 m·min⁻¹ vs. 16.89±1.15 m·min⁻¹, P<0.02, respectively). Moreover, the time to exhaustion during running at 12 m·min⁻¹ in IL-6⁻/⁻ mice was significantly shorter (P<0.05) than in WT mice. V'O(₂max) in IL-6⁻/⁻ (n = 20) amounting to 108.3±2.8 ml·kg⁻¹·min⁻¹ was similar as in WT mice (n = 22) amounting to 113.0±1.8 ml·kg⁻¹·min⁻¹, (P = 0.16). No difference in maximal COX activity between the IL-6⁻/⁻ and WT mice in m. soleus and m. gastrocnemius was found. Moreover, no impairment of peripheral endothelial function or glucose tolerance was found in IL-6⁻/⁻ mice. Surprisingly, plasma lactate concentration during running at 8 m·min⁻¹ as well at maximal running velocity in IL-6⁻/⁻ mice was significantly lower (P<0.01) than in WT mice. Interestingly, IL-6⁻/⁻ mice displayed important adaptive mechanisms including significantly lower oxygen cost of running at a given speed accompanied by lower expression of sarcoplasmic reticulum Ca²⁺-ATPase and lower plasma lactate concentrations during running at submaximal and maximal running velocities. In conclusion, impaired endurance running capacity in IL-6⁻/⁻ mice could not be explained by reduced V'O(₂max), endothelial dysfunction or impaired muscle oxidative capacity. Therefore, our results indicate that IL-6 cannot be regarded as a major regulator of exercise capacity but rather as a modulator of endurance performance. Furthermore, we identified important compensatory mechanism limiting reduced exercise performance in IL-6⁻/⁻ mice.

Endothelium as a gatekeeper of fatty acid transport

The endothelium transcends all clinical disciplines and is crucial to the function of every organ system. A critical, but poorly understood, role of the endothelium is its ability to control the transport of energy supply according to organ needs. Fatty acids (FAs) in particular represent a key energy source that is utilized by a number of tissues, but utilization must be tightly regulated to avoid potentially deleterious consequences of excess accumulation, including insulin resistance. Recent studies have identified important endothelial signaling mechanisms, involving vascular endothelial growth factor-B, peroxisome proliferator-activated receptor-γ, and apelin, that mediate endothelial regulation of FA transport. In this review, we discuss the mechanisms by which these signaling pathways regulate this key endothelial function.

Retargeting of gene expression using endothelium specific hexon modified adenoviral vector

Adenovirus serotype 5 (Ad5) vectors are well suited for gene therapy. However, tissue-selective transduction by systemically administered Ad5-based vectors is confounded by viral particle sequestration in the liver. Hexon-modified Ad5 expressing reporter gene under transcriptional control by the immediate/early cytomegalovirus (CMV) or the Roundabout 4 receptor (Robo4) enhancer/promoter was characterized by growth in cell culture, stability in vitro, gene transfer in the presence of human coagulation factor X, and biodistribution in mice. The obtained data demonstrate the utility of the Robo4 promoter in an Ad5 vector context. Substitution of the hypervariable region 7 (HVR7) of the Ad5 hexon with HVR7 from Ad serotype 3 resulted in decreased liver tropism and dramatically altered biodistribution of gene expression. The results of these studies suggest that the combination of liver detargeting using a genetic modification of hexon with an endothelium-specific transcriptional control element produces an additive effect in the improvement of Ad5 biodistribution.

Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes

Diets rich in green, leafy vegetables have been shown to lower blood pressure (BP) and reduce the risk of cardiovascular disease. Green, leafy vegetables and beetroot are particularly rich in inorganic nitrate. Dietary nitrate supplementation, via sequential reduction to nitrite and NO, has previously been shown to lower BP and improve endothelial function in healthy humans. We sought to determine if supplementing dietary nitrate with beetroot juice, a rich source of nitrate, will lower BP and improve endothelial function and insulin sensitivity in individuals with type 2 diabetes (T2DM). Twenty-seven patients, age 67.2±4.9 years (18 male), were recruited for a double-blind, randomized, placebo-controlled crossover trial. Participants were randomized to begin, in either order, a 2-week period of supplementation with 250ml beetroot juice daily (active) or 250ml nitrate-depleted beetroot juice (placebo). At the conclusion of each intervention period 24-h ambulatory blood pressure monitoring, tests of macro- and microvascular endothelial function, and a hyperinsulinemic isoglycemic clamp were performed. After 2 weeks administration of beetroot juice mean ambulatory systolic BP was unchanged: 134.6±8.4mmHg versus 135.1±7.8mmHg (mean±SD), placebo vs active-mean difference of -0.5mmHg (placebo-active), p=0.737 (95% CI -3.9 to 2.8). There were no changes in macrovascular or microvascular endothelial function or insulin sensitivity. Supplementation of the diet with 7.5mmol of nitrate per day for 2 weeks caused an increase in plasma nitrite and nitrate concentration, but did not lower BP, improve endothelial function, or improve insulin sensitivity in individuals with T2DM.

A novel porous scaffold fabrication technique for epithelial and endothelial tissue engineering

Porous scaffolds have the ability to minimize transport barriers for both two- (2D) and three-dimensional tissue engineering. However, current porous scaffolds may be non-ideal for 2D tissues such as epithelium due to inherent fabrication-based characteristics. While 2D tissues require porosity to support molecular transport, pores must be small enough to prevent cell migration into the scaffold in order to avoid non-epithelial tissue architecture and compromised function. Though electrospun meshes are the most popular porous scaffolds used today, their heterogeneous pore size and intense topography may be poorly-suited for epithelium. Porous scaffolds produced using other methods have similar unavoidable limitations, frequently involving insufficient pore resolution and control, which make them incompatible with 2D tissues. In addition, many of these techniques require an entirely new round of process development in order to change material or pore size. Herein we describe "pore casting," a fabrication method that produces flat scaffolds with deterministic pore shape, size, and location that can be easily altered to accommodate new materials or pore dimensions. As proof-of-concept, pore-cast poly(ε-caprolactone) (PCL) scaffolds were fabricated and compared to electrospun PCL in vitro using canine kidney epithelium, human colon epithelium, and human umbilical vein endothelium. All cell types demonstrated improved morphology and function on pore-cast scaffolds, likely due to reduced topography and universally small pore size. These results suggest that pore casting is an attractive option for creating 2D tissue engineering scaffolds, especially when the application may benefit from well-controlled pore size or architecture.

Testosterone deficiency in male heart failure patients and its effect on endothelial progenitor cells

BACKGROUND

Endothelial progenitor cells (EPCs) are thought to contribute to reendothelialization and neoangiogenesis. Since it is known that EPCs express a testosterone receptor, we wanted to assess the prevalence of testosterone deficiency in patients with CHF and its impact on circulating EPCs.

METHODS

137 male patients with chronic heart failure (CHF) were included (age 61 ± 13 years; BMI 29 ± 5 kg/m(2); New York Heart Association classification (NYHA) I: n = 47, NYHA II: n = 51, NYHA III: n = 39). Numbers of different populations of circulating EPCs were quantified using flow cytometry. Levels of free testosterone and EPC-regulating cytokines were determined using ELISA.

RESULTS

The prevalence of testosterone deficiency in our University CHF clinic was 39%. However, there was no difference between patients with and without testosterone deficiency regarding their levels of EPCs. Testosterone levels were inversely correlated with age (R(2) = -0.32, p = 0.001) and NYHA status (R(2) = 0.28, p = 0.001) and correlated with cardiorespiratory capacity (R(2) = 0.26, p = 0.03).

CONCLUSION

Testosterone deficiency is frequent in male patients with CHF but does not appear to impact the regenerative EPCs.

RhoA GTPase switch controls Cx43-hemichannel activity through the contractile system

ATP-dependent paracrine signaling, mediated via the release of ATP through plasma membrane-embedded hemichannels of the connexin family, coordinates a synchronized response between neighboring cells. Connexin 43 (Cx43) hemichannels that are present in the plasma membrane need to be tightly regulated to ensure cell viability. In monolayers of bovine corneal endothelial cells (BCEC),Cx43-mediated ATP release is strongly inhibited when the cells are treated with inflammatory mediators, in particular thrombin and histamine. In this study we investigated the involvement of RhoA activation in the inhibition of hemichannel-mediated ATP release in BCEC. We found that RhoA activation occurs rapidly and transiently upon thrombin treatment of BCEC. The RhoA activity correlated with the onset of actomyosin contractility that is involved in the inhibition of Cx43 hemichannels. RhoA activation and inhibition of Cx43-hemichannel activity were both prevented by pre-treatment of the cells with C3-toxin as well as knock down of RhoA by siRNA. These findings provide evidence that RhoA activation is a key player in thrombin-induced inhibition of Cx43-hemichannel activity. This study demonstrates that RhoA GTPase activity is involved in the acute inhibition of ATP-dependent paracrine signaling, mediated by Cx43 hemichannels, in response to the inflammatory mediator thrombin. Therefore, RhoA appears to be an important molecular switch that controls Cx43 hemichannel openings and hemichannel-mediated ATP-dependent paracrine intercellular communication under (patho)physiological conditions of stress.

Role of vascular endothelial growth factor and angiopoietin 1 in renal injury in hemolytic uremic syndrome

BACKGROUND/AIMS

The recovery process from renal injury in hemolytic uremic syndrome (HUS) remains obscure. In order to clarify the role of vascular endothelial growth factor (VEGF) and angiopoietin 1 (Ang-1) in the renal recovery from HUS, we produced a model of mild HUS and examined the renal recovery process.

METHODS

We investigated three groups of mice. Group 1 consisted of mice that received an injection of Shiga toxin 2 (Stx2) and lipopolysaccharide (LPS); group 2 consisted of mice that received an injection of low dose of Stx2 and LPS, and group 3 consisted of control mice.

RESULTS

Serum Cr levels in group 1 were greater than those in group 2, and all mice in group 1 died, whereas all mice in group 2 remained alive. Endothelial injury at 24 h in group 1 was higher than in group 2. Electron-microscopic findings demonstrated that the endothelial cells formed immature capillary-like lumina from 7 to 28 days with increases in the expression of CD31-positive cells. Glomerular VEGF expression decreased at 72 h in group 1, but gradually increased in group 2. Glomerular Ang-1 expression peaked from 72 h to 28 days. Ang-1 expression was frequently found in the endothelial cell region of vesicle walls simultaneous with increased CD31-positive staining.

CONCLUSION

Our findings suggest that VEGF and Ang-1 play important roles in the recovery process, particularly in the regeneration of endothelial injury.

[Correction of endothelial dysfunction by L-arginine under experimental pre-eclampsia conditions]

The ADMA-like pre-eclampsia in pregnant rats was modeled by daily introduction of L-NAME in a dose of 25 mg/kg for 7 days. L-arginine (200 mg/kg) prevented the development of arterial hypertension and a decrease in placentary microcirculation and microalbuminuria. The possibility of using L-arginine for the prevention of competitive eNOS inhibition by ADMA is discussed.

Endothelial microparticles in transplant patients - great potential but a long way to go

This overview provides information on the current state of endothelial microparticle research. Microparticles are small membrane vesicles shed by different cell types, which contain cell surface proteins and cytoplasmic components of the original cell. The microparticle production is a part of normal cell function, but it increases by apoptotic cells and cells under stress. Numerous evidences suggest that circulating endothelial microparticles may be a marker of endothelial cell function. Endothelial cells play an important role in the pathogenesis of allograft dysfunction and rejection. The endothelium is one of the main targets in allograft rejection. Recent studies have indicated that levels of circulating endothelial microparticles change in patients with solid organ transplants, including kidneys. We believe that circulating endothelial microparticles may be a useful tool of allograft function monitoring and/or a diagnostic marker of allograft rejection.

P-selectin mediates neutrophil rolling and recruitment in acute pancreatitis

BACKGROUND

The adhesive mechanisms regulating leucocyte-endothelium interactions in the pancreas remain elusive, but selectins may play a role. This study examined the molecular mechanisms mediating leucocyte rolling along the endothelium in the pancreas and the therapeutic potential of targeting the rolling adhesive interaction in acute pancreatitis (AP).

METHODS

Pancreatitis was induced by retrograde infusion of 5 per cent sodium taurocholate into the pancreatic duct, repeated intraperitoneal administration of caerulein (50 µg/kg) or intraperitoneal administration of L-arginine (4 g/kg) in C57BL/6 mice. A control and a monoclonal antibody against P-selectin were administered before and after induction of AP. Serum and tissue were sampled to assess the severity of pancreatitis, and intravital microscopy was used to study leucocyte rolling.

RESULTS

Taurocholate infusion into the pancreatic duct increased the serum level of trypsinogen, trypsinogen activation, pancreatic neutrophil infiltration, macrophage inflammatory protein (MIP) 2 formation and tissue damage. Immunoneutralization of P-selectin decreased the taurocholate-induced increase in serum trypsinogen (median (range) 17·35 (12·20-30·00) versus 1·55 (0·60-15·70) µg/l; P = 0·017), neutrophil accumulation (4·00 (0·75-4·00) versus 0·63 (0-3·25); P = 0·002) and tissue damage, but had no effect on MIP-2 production (14·08 (1·68-33·38) versus 3·70 (0·55-51·80) pg/mg; P = 0·195) or serum trypsinogen activating peptide level (1·10 (0·60-1·60) versus 0·45 (0-1·80) µg/l; P = 0·069). Intravital fluorescence microscopy revealed that anti-P-selectin antibody inhibited leucocyte rolling completely in postcapillary venules of the inflamed pancreas.

CONCLUSION

Inhibition of P-selectin protected against pancreatic tissue injury in experimental pancreatitis. Targeting P-selectin may be an effective strategy to ameliorate inflammation in AP.

Notch initiates the endothelial-to-mesenchymal transition in the atrioventricular canal through autocrine activation of soluble guanylyl cyclase

The heart is the most common site of congenital defects, and valvuloseptal defects are the most common of the cardiac anomalies seen in the newborn. The process of endothelial-to-mesenchymal transition (EndMT) in the cardiac cushions is a required step during early valve development, and Notch signaling is required for this process. Here we show that Notch activation induces the transcription of both subunits of the soluble guanylyl cyclase (sGC) heterodimer, GUCY1A3 and GUCY1B3, which form the nitric oxide receptor. In parallel, Notch also promotes nitric oxide (NO) production by inducing Activin A, thereby activating a PI3-kinase/Akt pathway to phosphorylate eNOS. We thus show that the activation of sGC by NO through a Notch-dependent autocrine loop is necessary to drive early EndMT in the developing atrioventricular canal (AVC).

Recent advances in liver sinusoidal endothelial ultrastructure and fine structure immunocytochemistry

Ultrastructure reports have described that liver sinusoidal endothelial cell (LSEC)s contain a cytoskeletal framework of filamentous actin. Small G protein has emerged as an important regulator of the actin cytoskeleton, and consequently, of cell morphology and motility. We investigated actin filaments in relation to SEF in LSECs using a heavy meromyosin-decorated reaction and thereby elucidated the roles of small G protein and actin cytoskeleton in the morphological and functional alterations of SEF. Caveolin-1 expression has also been found in fenestrations with many characteristics of liver sinusoidal endothelial cells. Currently, fenestral studies and human disease are revealing ways to increase the liver sieve's porosity, which is reduced through pathological mechanisms. Hepatic sinusoidal endothelial dysfunction, which is known to impair endothelium-dependent relaxation in the liver microcirculation, contributes to increased intrahepatic vascular resistance.

Endothelialized biomaterials for tissue engineering applications in vivo

Rebuilding tissues involves the creation of a vasculature to supply nutrients and this in turn means that the endothelial cells (ECs) of the resulting endothelium must be a quiescent non-thrombogenic blood contacting surface. Such ECs are deployed on biomaterials that are composed of natural materials such as extracellular matrix proteins or synthetic polymers in the form of vascular grafts or tissue-engineered constructs. Because EC function is influenced by their origin, biomaterial surface chemistry and hemodynamics, these issues must be considered to optimize implant performance. In this review, we examine the recent in vivo use of endothelialized biomaterials and discuss the fundamental issues that must be considered when engineering functional vasculature.

Is there an association between non-functioning adrenal adenoma and endothelial dysfunction?

BACKGROUND AND AIM

Subtle changes in hypothalamic- pituitary-adrenal (HPA) axis of subjects with nonfunctioning adrenal adenoma may be associated with endothelial alterations. We sought to investigate endothelial function, visceral adiposity and osteoprotegerin (OPG) and interleukin- 18 (IL-18) levels in subjects with non-functioning adrenal adenomas.

SUBJECTS AND METHODS

The adenoma group included 40 subjects without clinical and subclinical findings of hypercortisolism or other adrenal gland disorders. Twenty-two body mass index-matched controls were also enroled. The patients and control subjects underwent hormonal evaluation and assessment of anthropometric and metabolic parameters. Endothelial function was assessed with flowmediated dilatation (FMD) of the brachial artery and intima media thickness (IMT) of common carotid arteries. Visceral adipose tissue area was measured by computed tomography. Plasma OPG and serum IL-18 levels were also measured.

RESULTS

When compared with healthy controls, the adenoma group had elevated systolic blood pressure, post-dexamethasone suppression test cortisol and reduced DHEAS. Visceral adipose tissue area and IMT of common carotid arteries were comparable. In the adenoma group, FMD of the brachial artery was significantly impaired and IL-18 level was significantly elevated. Visceral adipose tissue area was independently related with FMD. Homeostasis model assessment (HOMA) was the independent factor associated with visceral adipose tissue area. Cortisol, DHEAS and visceral adipose tissue area were independently associated with HOMA.

CONCLUSIONS

We achieved evidence that could be attributable to endothelial alterations in subjects with non-functioning adrenal adenomas. Impaired FMD appeared to be a consequence of subtle changes in HPA axis in terms of elevated cortisol and reduced DHEAS as these conditions were known to disturb endothelial-dependent vasodilatation.

Endothelial and cardiac regeneration from adipose tissues

For a long time, adipose tissue was only considered for its crucial role in energy balance and associated diseases. The discovery of the presence of immature cells highlights a putative role for these tissues as reservoirs of therapeutic cells. Indeed, since fat pads can be sampled by liposuction under local anesthesia in adult patients, adipose tissue represents a promising source of regenerative cells, particularly in cardiovascular regeneration. Indeed among other potentials, we and others have demonstrated the great angiogenic properties of adipose-derived stromal cells (ASCs) and the existence of peculiar cells, at least in mice, that are able to spontaneously give rise to functional cardiomyocytes. This review deciphers the different steps necessary to isolate, characterize, and manipulate such striking cells.

Role of sulfur-containing gaseous substances in the cardiovascular system

Gaseous mediators are important signaling molecules with properties that differ from other, larger signaling molecules. Small gaseous mediators readily cross cell membranes and can access sites on target molecules that would be inaccessible to bulkier molecules. They have a variety of signaling mechanisms, some well understood, some not. The family of gasotransmitters is growing, well known members include nitric oxide (NO) and carbon monoxide (CO). Newer candidates include the sulfur containing gases hydrogen sulfide (H2S), which has been shown to have a wide range of physiological functions, and more recently sulfur dioxide (SO2) has been studied as a potential new gasotransmitter. This review explores the production, regulation and role of the sulfur-containing gases H2S and SO2 at the level of the endothelial and vascular smooth muscle cells as well as the broader effects on the cardiovascular system under both physiological and pathophysiological conditions.

Discovery of novel mechanosensitive genes in vivo using mouse carotid artery endothelium exposed to disturbed flow

Recently, we showed that disturbed flow caused by a partial ligation of mouse carotid artery rapidly induces atherosclerosis. Here, we identified mechanosensitive genes in vivo through a genome-wide microarray study using mouse endothelial RNAs isolated from the flow-disturbed left and the undisturbed right common carotid artery. We found 62 and 523 genes that changed significantly by 12 hours and 48 hours after ligation, respectively. The results were validated by quantitative polymerase chain reaction for 44 of 46 tested genes. This array study discovered numerous novel mechanosensitive genes, including Lmo4, klk10, and dhh, while confirming well-known ones, such as Klf2, eNOS, and BMP4. Four genes were further validated for protein, including LMO4, which showed higher expression in mouse aortic arch and in human coronary endothelium in an asymmetric pattern. Comparison of in vivo, ex vivo, and in vitro endothelial gene expression profiles indicates that numerous in vivo mechanosensitive genes appear to be lost or dysregulated during culture. Gene ontology analyses show that disturbed flow regulates genes involved in cell proliferation and morphology by 12 hours, followed by inflammatory and immune responses by 48 hours. Determining the functional importance of these novel mechanosensitive genes may provide important insights into understanding vascular biology and atherosclerosis.

Calcium dobesilate inhibits the alterations in tight junction proteins and leukocyte adhesion to retinal endothelial cells induced by diabetes

OBJECTIVE

Calcium dobesilate (CaD) has been used in the treatment of diabetic retinopathy in the last decades, but its mechanisms of action are not elucidated. CaD is able to correct the excessive vascular permeability in the retina of diabetic patients and in experimental diabetes. We investigated the molecular and cellular mechanisms underlying the protective effects of CaD against the increase in blood-retinal barrier (BRB) permeability induced by diabetes.

RESEARCH DESIGN AND METHODS

Wistar rats were divided into three groups: controls, streptozotocin-induced diabetic rats, and diabetic rats treated with CaD. The BRB breakdown was evaluated using Evans blue. The content or distribution of tight junction proteins (occludin, claudin-5, and zonula occluden-1 [ZO-1]), intercellular adhesion molecule-1 (ICAM-1), and p38 mitogen-activated protein kinase (p38 MAPK) was evaluated by Western blotting and immunohistochemistry. Leukocyte adhesion was evaluated in retinal vessels and in vitro. Oxidative stress was evaluated by the detection of oxidized carbonyls and tyrosine nitration. NF-κB activation was measured by enzyme-linked immunosorbent assay.

RESULTS

Diabetes increased the BRB permeability and retinal thickness. Diabetes also decreased occludin and claudin-5 levels and altered the distribution of ZO-1 and occludin in retinal vessels. These changes were inhibited by CaD treatment. CaD also inhibited the increase in leukocyte adhesion to retinal vessels or endothelial cells and in ICAM-1 levels, induced by diabetes or elevated glucose. Moreover, CaD decreased oxidative stress and p38 MAPK and NF-κB activation caused by diabetes.

CONCLUSIONS

CaD prevents the BRB breakdown induced by diabetes, by restoring tight junction protein levels and organization and decreasing leukocyte adhesion to retinal vessels. The protective effects of CaD are likely to involve the inhibition of p38 MAPK and NF-κB activation, possibly through the inhibition of oxidative/nitrosative stress.