Ischemic neoangiogenesis enhanced by beta2-adrenergic receptor overexpression: a novel role for the endothelial adrenergic system

Benzodiazepine diazepam regulates cell surface β1-adrenergic receptor density in human monocytes

Downregulation of cell surface β-adrenergic receptors (β-AR) is an important adaptive response that prevents deleterious effects of receptor overstimulation. Various factors including reactive oxygen species cause β-AR downregulation. In this study, we evaluated the effects of ligands of the peripheral benzodiazepine receptor (PBR), a key protein in regulating oxidative stress, on surface density of endogenous β₁-and β₂-ARs in highly differentiated cells such as human monocytes, which express both β-AR subtypes. β-AR expression in human monocytes was evaluated by flow cytometry, qPCR and western blotting. Monocyte treatment with β-AR agonist isoproterenol did not change surface β₁-AR density while downregulating surface β₂-AR density. This effect was antagonized by the β-blocker propranolol. An opposite response was observed with benzodiazepine diazepam that led to a time-dependent reduction in β₁-AR density. In particular, while no significant downregulation was observed after 3 h of treatment, only 63% of β₁-ARs were still present on the cell surface after 48 h of treatment with diazepam at 1 μM. Treatment with the PBR antagonist PK11195, but not with propranolol, antagonized the effects of diazepam. No change in β₁-AR-mRNA or protein levels was observed at any time after diazepam treatment. We also found that diazepam did not affect Gs-protein or β-arrestin-2 recruitment for both β-ARs in engineered fibroblasts, further suggesting that diazepam activity on β₁-AR density is mediated by PBR. Finally, no sex-related differences were found. Collectively, these results indicate that monocyte β₁-ARs are resistant to catecholamine-mediated downregulation and suggest that PBR plays an important role in regulating β₁-AR density.

Is Infantile Hemangioma a Neuroendocrine Tumor?

Infantile hemangioma (IH) is the most common infantile tumor, affecting 5–10% of newborns. Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is currently the first-line treatment for severe IH; however, both its mechanism of action and its main cellular target remain poorly understood. Since betablockers can antagonize the effect of natural ADRB agonists, we postulated that the catecholamine produced in situ in IH may have a role in the propranolol response. By quantifying catecholamines in the IH tissues, we found a higher amount of noradrenaline (NA) in untreated proliferative IHs than in involuted IHs or propranolol-treated IHs. We further found that the first three enzymes of the catecholamine biosynthesis pathway are expressed by IH cells and that their levels are reduced in propranolol-treated tumors. To study the role of NA in the pathophysiology of IH and its response to propranolol, we performed an in vitro angiogenesis assay in which IH-derived endothelial cells, pericytes and/or telocytes were incorporated. The results showed that the total tube formation is sensitive to propranolol only when exogenous NA is added in the three-cell model. We conclude that the IH’s sensitivity to propranolol depends on crosstalk between the endothelial cells, pericytes and telocytes in the context of a high local amount of local NA.

Decoupling Oxygen Tension From Retinal Vascularization as a New Perspective for Management of Retinopathy of Prematurity. New Opportunities From β-adrenoceptors

Retinopathy of prematurity (ROP) is an evolutive and potentially blinding eye disease that affects preterm newborns. Unfortunately, until now no conservative therapy of active ROP with proven efficacy is available. Although ROP is a multifactorial disease, premature exposition to oxygen concentrations higher than those intrauterine, represents the initial pathogenetic trigger. The increase of oxygenation in a retina still incompletely vascularized promotes the downregulation of proangiogenic factors and finally the interruption of vascularization (ischemic phase). However, the increasing metabolic requirement of the ischemic retina induces, over the following weeks, a progressive hypoxia that specularly increases the levels of proangiogenic factors finally leading to proliferative retinopathy (proliferative phase). Considering non-modifiable the coupling between oxygen levels and vascularization, so far, neonatologists and ophthalmologists have “played defense”, meticulously searching the minimum necessary concentration of oxygen for individual newborns, refining their diagnostic ability, adopting a careful monitoring policy, ready to decisively intervene only in a very advanced stage of disease progression. However, recent advances have demonstrated the possibility to pharmacologically modulate the relationship between oxygen and vascularization, opening thus the perspective for new therapeutic or preventive opportunities. The perspective of a shift from a defensive towards an attack strategy is now at hand.

The Adrenergic Nerve Network in Cancer

The central and autonomic nervous systems interact and converge to build up an adrenergic nerve network capable of promoting cancer. While a local adrenergic sympathetic innervation in peripheral solid tumors influences cancer and stromal cell behavior, the brain can participate to the development of cancer through an intermixed dysregulation of the sympathoadrenal system, adrenergic neurons, and the hypothalamo-pituitary-adrenal axis. A deeper understanding of the adrenergic nerve circuitry within the brain and tumors and its interactions with the microenvironment should enable elucidation of original mechanisms of cancer and novel therapeutic strategies.

Potential Regulatory Roles of GRK2 in Endothelial Cell Activity and Pathological Angiogenesis

G protein-coupled receptor (GPCR) kinase 2 (GRK2) is an integrative node in many signaling network cascades. Emerging evidence indicates that GRK2 can interact with a large number of GPCRs and non-GPCR substrates in both kinase-dependent and -independent modes. Some of these pathways are associated with endothelial cell (EC) activity. The active state of ECs is a pivotal factor in angiogenesis. The occurrence and development of some inflammation-related diseases are accompanied by pathological angiogenesis, but there remains a lack of effective targeted treatments. Alterations in the expression and/or localization of GRK2 have been identified in several types of diseases and have been demonstrated to regulate the angiogenesis process in these diseases. GRK2 as a target may be a promising candidate for anti-angiogenesis therapy.

Importance of β2AR elevation for re-endothelialization capacity mediated by late endothelial progenitor cells in hypertensive patients

Dysfunction of late endothelial progenitor cells (EPCs) has been suggested to be associated with hypertension. β2-Adrenergic receptor (β2AR) is a novel and key target for EPC homing. Here, we proposed that attenuated β2AR signaling contributes to EPCs dysfunction, whereas enhanced β2AR signaling restores EPCs' functions in hypertension. EPCs derived from hypertensive patients exhibited reduced cell number, impaired in vitro migratory and adhesion abilities, and impaired re-endothelialization after transplantation in nude mice with carotid artery injury. β2AR expression of EPCs from hypertensive patients was markedly downregulated, whereas the phosphorylation of the p38 mitogen-activated protein kinase (p38-MAPK) was elevated. The cleaved caspase-3 levels were elevated in EPCs. The overexpression of β2AR in EPCs from hypertensive patients inhibited p38-MAPK signaling, whereas it enhanced in vitro EPC proliferation, migration, and adhesion and in vivo re-endothelialization. The β2AR-mediated effects were attenuated by treating the EPCs with a neutralizing monoclonal antibody against β2AR, which could be partially antagonized by the p38-MAPK inhibitor SB203580. Moreover, shear stress stimulation, a classic nonpharmacological intervention, increased the phosphorylation levels of β2AR and enhanced the in vitro and in vivo functions of EPCs from hypertensive patients. Collectively, the current investigation demonstrated that impaired β2AR/p38-MAPK/caspase-3 signaling at least partially reduced the re-endothelialization capacity of EPCs from hypertensive patients. Restoration of β2AR expression and shear stress treatment could improve their endothelial repair capacity by regulating the p38-MAPK/caspase-3 signaling pathway. The clinical significance of β2AR in endothelium repair still requires further investigation.NEW & NOTEWORTHY Impaired β2-adrenergic receptor (β2AR) expression with an elevation of p38-MAPK/caspase-3 signaling at least partially contributes to the decline of re-endothelialization capacity of late endothelial progenitor cells (EPCs) from hypertensive patients. β2AR gene transfer and shear stress treatment improve the late EPC-mediated enhancement of the re-endothelialization capacity in hypertensive patients through activating β2AR/p38-MAPK/caspase-3 signaling. The present study is the first to reveal the potential molecular mechanism of the impaired endothelium-reparative capacity of late EPCs in hypertension after vascular injury and strongly suggests that β2AR is a novel and crucial therapeutic target for increasing EPC-mediated re-endothelialization capacity in hypertension.

Saudi Arabia Guidelines for diabetic macular edema: A consensus of the Saudi Retina Group

Diabetes mellitus (DM) and its complications are major public health burdens in Saudi Arabia. The prevalence of diabetic retinopathy (DR) is 19.7% and the prevalence of diabetic macular edema (DME) is 5.7% in Saudi Arabia. Diabetic macular edema is a vision-threatening complication of DR and a major cause of vision loss worldwide. Ocular treatments include retinal laser photocoagulation, anti-vascular endothelial growth factor (anti-VEGF) agents, intravitreal corticosteroids, and vitreoretinal surgery when necessary. The present consensus was developed as a part of the Saudi Retina Group's efforts to generate Saudi guidelines and consensus for the management of DME, including recommendations for its diagnosis, treatment, and best practice. The experts' panel stipulates that the treatment algorithm should be categorized according to the presence of central macula involvement. In patients with no central macular involvement, laser photocoagulation is recommended as the first-line option. Patients with central macular involvement and no recent history of cardiovascular (CVS) or cerebrovascular disorders can be offered anti-VEGF agents as the first-line option. In the case of non-responders (defined as an improvement of <20% in optical coherence tomography or a gain of fewer than 5 letters in vision), switching to another anti-VEGF agent or steroids should be considered after 3 injections. Within the class of steroids, dexamethasone implants are recommended as the first choice. In patients with a recent history of CVS events, the use of anti-VEGF agents is not recommended, regardless of their lens status. The experts' panel recommends that a future study be conducted to provide a cut-off point for early switching to steroid implants in pseudo-phakic eyes.

Functions of beta2-adrenergic receptor in human periodontal ligament cells

Adrenergic receptors (ARs) are receptors of noradrenalin and adrenalin, of which there are nine different subtypes. In particular, β2 adrenergic receptor (β2-AR) is known to be related to the restoration and maintenance of homeostasis in bone and cardiac tissues; however, the functional role of signaling through β2-AR in periodontal ligament (PDL) tissue has not been fully examined. In this report, we investigated that β2-AR expression in PDL tissues and their features in PDL cells. β2-AR expressed in rat PDL tissues and human PDL cells (HPDLCs) derived from two different patients (HPDLCs-2G and -3S). Rat PDL tissue with occlusal loading showed high β2-AR expression, while its expression was downregulated in that without loading. In HPDLCs, β2-AR expression was increased exposed to stretch loading. The gene expression of PDL-related molecules was investigated in PDL clone cells (2-23 cells) overexpressing β2-AR. Their gene expression and intracellular cyclic adenosine monophosphate (cAMP) levels were also investigated in HPDLCs treated with a specific β2-AR agonist, fenoterol (FEN). Overexpression of β2-AR significantly promoted the gene expression of PDL-related molecules in 2 to 23 cells. FEN led to an upregulation in the expression of PDL-related molecules and increased intracellular cAMP levels in HPDLCs. In both HPDLCs, inhibition of cAMP signaling by using protein kinase A inhibitor suppressed the FEN-induced gene expression of α-smooth muscle actin. Our findings suggest that the occlusal force is important for β2-AR expression in PDL tissue and β2-AR is involved in fibroblastic differentiation and collagen synthesis of PDL cells. The signaling through β2-AR might be important for restoration and homeostasis of PDL tissue.

Arrb2 promotes endothelial progenitor cell-mediated postischemic neovascularization

Background and aim: Modulating biological functions of endothelial progenitor cells (EPCs) is essential for therapeutic angiogenesis in ischemic vascular diseases. This study aimed to explore the role and molecular mechanisms of β-arrestin 2 (Arrb2) in EPCs biology and angiogenic therapy. Methods: The influence of Arrb2 on postischemic neovascularization was evaluated in Arrb2-deficient mice. The proliferation, apoptosis, and various functions of EPCs were analyzed in vitro by manipulating the expression of Arrb2. Finally, the in vivo effect of Arrb2 on EPC-mediated neovascularization was investigated in a mouse model of hind-limb ischemia (HLI). Results: Arrb2-deficient mice exhibited impaired blood flow recovery based on laser Doppler measurements and reduced capillary density in the adductor muscle after unilateral HLI. Arrb2-deficient mice also showed restricted intraplug angiogenesis in subcutaneously implanted Matrigel plugs. In vitro, lentivirus-mediated Arrb2 overexpression promoted EPC proliferation, migration, adhesion, and tube formation, whereas Arrb2 knockdown had opposite effects. In addition, the overexpression of Arrb2 in EPCs protected them from hypoxia-induced apoptosis and improved intraplug angiogenesis ex vivo. Mechanistically, Arrb2 interacted with and activated extracellular signal-regulated kinase (ERK)1/2 and protein kinase B (Akt) signaling pathways. Finally, the transplantation of EPCs overexpressing Arrb2 resulted in a significantly higher blood flow restoration in ischemic hind limb and higher capillary density during histological analysis compared with control or Arrb2-knockdown EPC-treated nude mice. Conclusions: The data indicated that Arrb2 augmented EPC-mediated neovascularization through the activation of ERK and Akt signaling pathways. This novel biological function of Arrb2 might provide a potential therapeutic option to promote EPCs in the treatment of ischemic vascular diseases.

Arginine and Endothelial Function

Arginine (L-arginine), is an amino acid involved in a number of biological processes, including the biosynthesis of proteins, host immune response, urea cycle, and nitric oxide production. In this systematic review, we focus on the functional role of arginine in the regulation of endothelial function and vascular tone. Both clinical and preclinical studies are examined, analyzing the effects of arginine supplementation in hypertension, ischemic heart disease, aging, peripheral artery disease, and diabetes mellitus.

Can propranolol prevent progression of melanoma?

The worldwide incidence of melanoma has risen rapidly in the past 50 years and is a considerable public health burden in the United States, with significant financial implications. Studies have demonstrated the potential anticarcinogenic effects of antihypertensive agents, specifically beta-blockers, in patients with prostate cancer, breast cancer, and lately cutaneous malignant melanoma. This article explores the empirical clinical evidence of propranolol's anticarcinogenic effects on melanoma and the chemoprotective mechanisms of beta-blockers and other agents that have been used to modify melanoma progression.

Dissection of heterocellular cross-talk in vascularized cardiac tissue mimetics

Cellular specialization and interaction with other cell types in cardiac tissue is essential for the coordinated function of cell populations in the heart. The complex interplay between cardiomyocytes, endothelial cells and fibroblasts is necessary for adaptation but can also lead to pathophysiological remodeling. To understand this complex interplay, we developed 3D vascularized cardiac tissue mimetics (CTM) to study heterocellular cross-talk in hypertrophic, hypoxic and fibrogenic environments. This 3D platform responds to physiologic and pathologic stressors and mimics the microenvironment of diseased tissue. In combination with endothelial cell fluorescence reporters, these cardiac tissue mimetics can be used to precisely visualize and quantify cellular and functional responses upon stress stimulation. Utilizing this platform, we demonstrate that stimulation of α/β-adrenergic receptors with phenylephrine (PE) promotes cardiomyocyte hypertrophy, metabolic maturation and vascularization of CTMs. Increased vascularization was promoted by conditioned medium of PE-stimulated cardiomyocytes and blocked by inhibiting VEGF or upon β-adrenergic receptor antagonist treatment, demonstrating cardiomyocyte-endothelial cross-talk. Pathophysiological stressors such as severe hypoxia reduced angiogenic sprouting and increased cell death, while TGF β2 stimulation increased collagen deposition concomitant to endothelial-to-mesenchymal transition. In sum, we have developed a cardiac 3D culture system that reflects native cardiac tissue function, metabolism and morphology - and for the first time enables the tracking and analysis of cardiac vascularization dynamics in physiology and pathology.

G-Protein-Coupled Receptors in Heart Disease

GPCRs (G-protein [guanine nucleotide-binding protein]-coupled receptors) play a central physiological role in the regulation of cardiac function in both health and disease and thus represent one of the largest class of surface receptors targeted by drugs. Several antagonists of GPCRs, such as βARs (β-adrenergic receptors) and Ang II (angiotensin II) receptors, are now considered standard of therapy for a wide range of cardiovascular disease, such as hypertension, coronary artery disease, and heart failure. Although the mechanism of action for GPCRs was thought to be largely worked out in the 80s and 90s, recent discoveries have brought to the fore new and previously unappreciated mechanisms for GPCR activation and subsequent downstream signaling. In this review, we focus on GPCRs most relevant to the cardiovascular system and discuss traditional components of GPCR signaling and highlight evolving concepts in the field, such as ligand bias, β-arrestin-mediated signaling, and conformational heterogeneity.

Antiangiogenic potential of beta-blockers in the context of juvenile hemangioma treatment

Juvenile hemangiomas (JH) — the most common tumor of childhood, which is estimated by various investigators found in 3–10 % of newborns resulting from the local development of significant violations of neoangiogenesis regulation. Research objective: determination of comparative antiangiogenic effectiveness and influence of beta-blockers on the level of a vascular endothelial factor of growth in an experiment. Material and methods. For determination of antiangiogenic effect of beta blockers, comparative studying of their influence on the level of a vascular endothelial factor of growth in an experiment on 72 nonlinear laboratory rats, by average weight 180 ± 20 g which were conditionally divided into 6 groups is executed: 1 — control, 2 — negative control — experimental ischemia (EI, crossing of femoral vessels), 3 — positive control (EI with bevacizumab introduction), 4 — EI with introduction of a timolol, 5 — EI with introduction of a betaksolol, 6 — EI with introduction of interferon alpha 2b. Results. The VEGF levels were: in 1 group — 1.50 ± 0.3 pg/ml, in 2 — 20.3 ± 3.2 pg/ml, 3 — 5.8 ± 0.9 pg/ml, 4 — 13.8 ± 1.4 pg/ml, 5 — 19.2 ± 2.3 pg/ml and 6 — 11.1 ± 2.2 pg/ml. Results of microscopy and immunohistochemical research demonstrate lack of activation of processes of neoangiogenesis in 1 group of animals. At animals of 2nd and 5th groups along with the expressed inflammatory processes the neoangiogenesis phenomena are established. Conclusion. Beta-blockers show the direct or mediated negative impact on synthesis of VEGF and oppression of neoangiogenesis. The activity of selective beta-blocker concerning neoangiogenesis suppression — was lower in comparison by activity non-selective that allows to consider the Timolol effective antiangiogenic remedy.

The effect of propranolol on the prognosis of hepatocellular carcinoma: A nationwide population-based study

Background

Beta-blockers can reduce recurrence, metastasis, and mortality in various cancers. In this study, we investigated the effect of propranolol, a non-selective beta-blocker on overall survival (OS) in unresectable/metastatic hepatocellular carcinoma (HCC) and on recurrence-free survival (RFS) in resectable, curable HCC.

Methods

Data were retrieved from the Taiwan National Health Insurance Research Database between January 2000 and December 2013. Propranolol users (for >1 year) and non-propranolol users were matched using a 1:2 propensity score in both cohorts.

Results

The unresectable/metastatic HCC cohort comprised 1,560 propranolol users and 3,120 non-propranolol users (control group). On multivariate Cox regression analysis of HCC mortality, propranolol significantly reduced the mortality risk by 22% (hazard ratio [HR] = 0.78, 95% confidence interval [CI] 0.72–0.84, P <0.001). On stratified Cox regression analysis, propranolol also reduced the mortality risk in HCC patients with hepatitis B (HR = 0.92, 95% CI 0.85–0.99, P = 0.045), hepatitis C (HR = 0.85, 95% CI = 0.78–0.92, P = 0.001), liver cirrhosis (HR = 0.78, 95% CI = 0.72–0.85, P <0.001), and diabetes mellitus (HR = 0.87, 95% CI = 0.81–0.94, P = 0.008). The resectable, curable HCC cohort comprised 289 propranolol users and 578 non-propranolol users (control group), but there was no significant difference in RFS (P = 0.762) between propranolol and non-propranolol users.

Conclusion

This study revealed that propranolol could improve OS in unresectable/metastatic HCC.

Insights into Endothelial Progenitor Cells: Origin, Classification, Potentials, and Prospects

With the discovery of endothelial progenitor cells (EPCs) in the late 1990s, a paradigm shift in the concept of neoangiogenesis occurred. The identification of circulating EPCs in peripheral blood marked the beginning of a new era with enormous potential in the rapidly transforming regenerative field. Overwhelmed with the revelation, researchers across the globe focused on isolating, defining, and interpreting the role of EPCs in various physiological and pathological conditions. Consequently, controversies emerged regarding the isolation techniques and classification of EPCs. Nevertheless, the potential of using EPCs in tissue engineering as an angiogenic source has been extensively explored. Concomitantly, the impact of EPCs on various diseases, such as diabetes, cancer, and cardiovascular diseases, has been studied. Within the limitations of the current knowledge, this review attempts to delineate the concept of EPCs in a sequential manner from the speculative history to a definitive presence (origin, sources of EPCs, isolation, and identification) and significance of these EPCs. Additionally, this review is aimed at serving as a guide for investigators, identifying potential research gaps, and summarizing our current and future prospects regarding EPCs.

Angiotensin II Attenuates the Bioactivities of Human Endothelial Progenitor Cells via Downregulation of β2-Adrenergic Receptor

Cross talks between the renin-angiotensin system (RAS), sympathetic nervous system, and vascular homeostasis are tightly coordinated in hypertension. Angiotensin II (Ang II), a key factor in RAS, when abnormally activated, affects the number and bioactivity of circulating human endothelial progenitor cells (hEPCs) in hypertensive patients. In this study, we investigated how the augmentation of Ang II regulates adrenergic receptor-mediated signaling and angiogenic bioactivities of hEPCs. Interestingly, the short-term treatment of hEPCs with Ang II drastically attenuated the expression of beta-2 adrenergic receptor (ADRB2), but did not alter the expression of beta-1 adrenergic receptor (ADRB1) and Ang II type 1 receptor (AT1R). EPC functional assay clearly demonstrated that the treatment with ADRB2 agonists significantly increased EPC bioactivities including cell proliferation, migration, and tube formation abilities. However, EPC bioactivities were decreased dramatically when treated with Ang II. Importantly, the attenuation of EPC bioactivities by Ang II was restored by treatment with an AT1R antagonist (telmisartan; TERT). We found that AT1R binds to ADRB2 in physiological conditions, but this binding is significantly decreased in the presence of Ang II. Furthermore, TERT, an Ang II-AT1R interaction blocker, restored the interaction between AT1R and ADRB2, suggesting that Ang II might induce the dysfunction of EPCs via downregulation of ADRB2, and an AT1R blocker could prevent Ang II-mediated ADRB2 depletion in EPCs. Taken together, our report provides novel insights into potential therapeutic approaches for hypertension-related cardiovascular diseases.

Effect of carvedilol vs metoprolol succinate on mortality in heart failure with reduced ejection fraction

BACKGROUND

Beta blocker therapy is indicated in all patients with heart failure with reduced ejection fraction (HFrEF) as per current guidelines. The relative benefit of carvedilol to metoprolol succinate remains unknown. This study aimed to compare survival benefit of carvedilol to metoprolol succinate.

METHODS

The VA's databases were queried to identify 114,745 patients diagnosed with HFrEF from 2007 to 2015 who were prescribed carvedilol and metoprolol succinate. The study estimated the survival probability and hazard ratio by comparing the carvedilol and metoprolol patients using propensity score matching with replacement techniques on observed covariates. Sub-group analyses were performed separately for men, women, elderly, duration of therapy of more than 3 months, and diabetic patients.

RESULTS

A total of 43,941 metoprolol patients were matched with as many carvedilol patients. The adjusted hazard ratio of mortality for metoprolol succinate compared to carvedilol was 1.069 (95% CI: 1.046-1.092, P value: < .001). At six years, the survival probability was higher in the carvedilol group compared to the metoprolol succinate group (55.6% vs 49.2%, P value < .001). The sub-group analyses show that the results hold true separately for male, over or under 65 years old, therapy duration more than three months and non-diabetic patients.

CONCLUSION

Patients with HFrEF taking carvedilol had improved survival as compared to metoprolol succinate. The data supports the need for furthering testing to determine optimal choice of beta blockers in patients with heart failure with reduced ejection fraction.

Study protocol: safety and efficacy of propranolol 0.2% eye drops in newborns with a precocious stage of retinopathy of prematurity (DROP-ROP-0.2%): a multicenter, open-label, single arm, phase II trial

BACKGROUND

Retinopathy of prematurity (ROP) still represents one of the leading causes of visual impairment in childhood. Systemic propranolol has proven to be effective in reducing ROP progression in preterm newborns, although safety was not sufficiently guaranteed. On the contrary, topical treatment with propranolol eye micro-drops at a concentration of 0.1% had an optimal safety profile in preterm newborns with ROP, but was not sufficiently effective in reducing the disease progression if administered at an advanced stage (during stage 2). The aim of the present protocol is to evaluate the safety and efficacy of propranolol 0.2% eye micro-drops in preterm newborns at a more precocious stage of ROP (stage 1).

METHODS

A multicenter, open-label, phase II, clinical trial, planned according to the Simon optimal two-stage design, will be performed to analyze the safety and efficacy of propranolol 0.2% eye micro-drops in preterm newborns with stage 1 ROP. Preterm newborns with a gestational age of 23-32 weeks, with a stage 1 ROP will receive propranolol 0.2% eye micro-drops treatment until retinal vascularization has been completed, but for no longer than 90 days. Hemodynamic and respiratory parameters will be continuously monitored. Blood samplings checking metabolic, renal and liver functions, as well as electrocardiogram and echocardiogram, will be periodically performed to investigate treatment safety. Additionally, propranolol plasma levels will be measured at the steady state, on the 10th day of treatment. To assess the efficacy of topical treatment, the ROP progression from stage 1 ROP to stage 2 or 3 with plus will be evaluated by serial ophthalmologic examinations.

DISCUSSION

Propranolol eye micro-drops could represent an ideal strategy in counteracting ROP, because it is definitely safer than oral administration, inexpensive and an easily affordable treatment. Establishing the optimal dosage and treatment schedule is to date a crucial issue.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02504944, registered on July 19, 2015, updated July 12, 2016. EudraCT Number 2014-005472-29.

Opposite effects of β2-adrenoceptor gene deletion on insulin signaling in liver and skeletal muscle

BACKGROUND AND AIM

β₂-Adrenoceptors (β₂-ARs) are G protein-coupled receptors (GPCRs) expressed in the major insulin target tissues. The interplay between β₂-AR and insulin pathways is involved in the maintenance of glucose homeostasis. The aim of this study was to explore the consequences of β₂-ARs deletion on insulin sensitivity and insulin signaling cascade in metabolically active tissues.

METHODS AND RESULTS

We evaluated glucose homeostasis in skeletal muscle and liver of β₂-AR-null mice (β₂-AR^-/-) by performing in vivo (glucose tolerance test and insulin tolerance test) and ex vivo (glucose uptake and glycogen determination) experiments. β₂-AR gene deletion is associated with hepatic insulin resistance and preserved skeletal muscle insulin sensitivity. Importantly, we demonstrate that hepatic β₂-AR regulates insulin-induced AKT activation via Grb2-mediated SRC recruitment through a G_i-independent mechanism.

CONCLUSIONS

β-AR stimulation contributes to the development of early stages of insulin resistance progression in the liver. Our findings indicate that the cross-talk between β₂-AR and insulin signaling represents a fundamental target towards the development of novel therapeutic approaches to treat type 2 diabetes and metabolic syndrome.

β2-Adrenergic Receptor Antagonism Attenuates CNV Through Inhibition of VEGF and IL-6 Expression

Purpose

The role of β–adrenergic receptor (AR) signaling in neovascular ocular diseases has recently emerged. We have previously reported that intraperitoneal propranolol inhibits choroidal neovascularization (CNV) in vivo and β2-AR blockade reduces vascular endothelial growth factor (VEGF) expression in mouse retinal pigment epithelium and choroidal endothelial cells in culture. Here we tested the hypothesis that the β2-AR regulates CNV through modulation of VEGF and inflammatory cytokine expression.

Methods

Mice were subjected to laser burns, inducing CNV, and were treated with an intravitreal β2-AR antagonist. After 3 and 5 days, total eye interleukin-6 (IL-6) and VEGF protein levels were measured, respectively. After 14 days, CNV was measured on choroidal–scleral flatmounts. The effects of β-AR signaling on VEGF and IL-6 expression were investigated in various mouse retinal and human RPE cells by using specific β-AR agonists and antagonists.

Results

β2–Adrenergic receptor signaling increased Vegf mRNA expression by approximately 3- to 4-fold in mouse retinal microglia and pericytes in culture. β2–Adrenergic receptor signaling upregulated IL-6 mRNA expression between 10- and 60-fold in mouse retinal microglia, pericytes, RPE, and choroidal endothelial cells in culture. Intravitreal injection of β2-AR antagonist ICI 118,551 reduced CNV by 35% and decreased IL-6 protein levels by approximately 50%. In primary human RPE cells, β2-AR activation also stimulated VEGF and IL-6 mRNA expression by 2- and 10-fold, respectively.

Conclusions

Anti-VEGF therapy for CNV is highly effective; however, some patients are resistant to therapy while others undergo repeated, frequent treatments. β2–Adrenergic receptor signaling is a potential therapeutic target because of its angiogenic and inflammatory properties.

Convergent ERK1/2, p38 and JNK mitogen activated protein kinases (MAPKs) signalling mediate catecholoestradiol-induced proliferation of ovine uterine artery endothelial cells

KEY POINTS

The catechol metabolites of 17β-oestradiol (E₂ β), 2-hydroxyoestradiol (2-OHE₂ ) and 4-hydroxyoestradiol (4-OHE₂ ), stimulate proliferation of pregnancy-derived ovine uterine artery endothelial cells (P-UAECs) through β-adrenoceptors (β-ARs) and independently of the classic oestrogen receptors (ERs). Herein we show that activation of ERK1/2, p38 and JNK mitogen activated protein kinases (MAPKs) is necessary for 2-OHE₂ - and 4-OHE₂ -induced P-UAEC proliferation, as well as proliferation induced by the parent hormone E₂ β and other β-AR signalling hormones (i.e. catecholamines). Conversely, although 2-OHE₂ and 4-OHE₂ rapidly activate phosphatidylinositol 3-kinase (PI3K), its activation is not involved in catecholoestradiol-induced P-UAEC proliferation. We also show for the first time the signalling mechanisms involved in catecholoestradiol-induced P-UAEC proliferation; which converge at the level of MAPKs with the signalling mechanisms mediating E₂ β- and catecholamine-induced proliferation. The present study advances our understanding of the complex signalling mechanisms involved in regulating uterine endothelial cell proliferation during pregnancy.

ABSTRACT

Previously we demonstrated that the biologically active metabolites of 17β-oestradiol, 2-hydroxyoestradiol (2-OHE₂ ) and 4-hydroxyoestradiol (4-OHE₂ ), stimulate pregnancy-specific proliferation of uterine artery endothelial cells derived from pregnant (P-UAECs), but not non-pregnant ewes. However, unlike 17β-oestradiol, which induces proliferation via oestrogen receptor-β (ER-β), the catecholoestradiols mediate P-UAEC proliferation via β-adrenoceptors (β-AR) and independently of classic oestrogen receptors. Herein, we aim to further elucidate the signalling mechanisms involved in proliferation induced by catecholoestradiols in P-UAECs. P-UAECs were treated with 2-OHE₂ and 4-OHE₂ for 0, 0.25, 0.5, 1, 2, 4, 12 and 24 h, to analyse activation of mitogen activated protein kinases (MAPKs) and phosphatidylinositol 3-kinase (PI3K)-AKT. Specific inhibitors for ERK1/2 MAPK (PD98059), p38 MAPK (SB203580), JNK MAPK (SP600125), or PI3K (LY294002) were used to determine the involvement of individual kinases in agonist-induced P-UAEC proliferation. 2-OHE₂ and 4-OHE₂ stimulated biphasic phosphorylation of ERK1/2, slow p38 and JNK phosphorylation over time, and rapid monophasic AKT phosphorylation. Furthermore, ERK1/2, p38 and JNK MAPKs, but not PI3K, were individually necessary for catecholoestradiol-induced proliferation. In addition, when comparing the signalling mechanisms of the catecholoestradiols, to 17β-oestradiol and catecholamines, we observed that convergent MAPKs signalling pathways facilitate P-UAEC proliferation induced by all of these hormones. Thus, all three members of the MAPK family mediate the mitogenic effects of catecholoestradiols in the endothelium during pregnancy. Furthermore, the convergent signalling of MAPKs involved in catecholoestradiol-, 17β-oestradiol- and catecholamine-induced endothelial cell proliferation may be indicative of unappreciated evolutionary functional redundancy to facilitate angiogenesis and ensure maintenance of uterine blood flow during pregnancy.

Dynamic regulation of VEGF-inducible genes by an ERK/ERG/p300 transcriptional network

The transcriptional pathways activated downstream of vascular endothelial growth factor (VEGF) signaling during angiogenesis remain incompletely characterized. By assessing the signals responsible for induction of the Notch ligand delta-like 4 (DLL4) in endothelial cells, we find that activation of the MAPK/ERK pathway mirrors the rapid and dynamic induction of DLL4 transcription and that this pathway is required for DLL4 expression. Furthermore, VEGF/ERK signaling induces phosphorylation and activation of the ETS transcription factor ERG, a prerequisite for DLL4 induction. Transcription of DLL4 coincides with dynamic ERG-dependent recruitment of the transcriptional co-activator p300. Genome-wide gene expression profiling identified a network of VEGF-responsive and ERG-dependent genes, and ERG chromatin immunoprecipitation (ChIP)-seq revealed the presence of conserved ERG-bound putative enhancer elements near these target genes. Functional experiments performed in vitro and in vivo confirm that this network of genes requires ERK, ERG and p300 activity. Finally, genome-editing and transgenic approaches demonstrate that a highly conserved ERG-bound enhancer located upstream of HLX (which encodes a transcription factor implicated in sprouting angiogenesis) is required for its VEGF-mediated induction. Collectively, these findings elucidate a novel transcriptional pathway contributing to VEGF-dependent angiogenesis.

Biphasic effects of propranolol on tumour growth in B16F10 melanoma-bearing mice

BACKGROUND AND PURPOSE

Propranolol is a vasoactive drug that shows antiangiogenic and antitumour activities in melanoma. However, it is unknown whether these activities are dose-dependent and whether there is a relationship between systemic vascular effects of propranolol and anti-melanoma activity.

EXPERIMENTAL APPROACH

Effects of increasing doses of propranolol (10, 20, 30 and 40 mg·kg^-1 ·day^-1 ) on tumour growth were studied in B16F10 melanoma-bearing mice. Histological and biochemical analyses were used to assess propranolol effects on angiogenesis and cancer cell proliferation. Systemic vascular resistance (SVR) was evaluated by measuring cardiac output and arterial BP.

KEY RESULTS

In vitro analyses revealed that B16F10 cells expressed β-adrenoceptors, but neither isoprenaline, a β-adrenoceptor agonist, nor the β-blocker propranolol affected cancer cell proliferation. In vivo studies showed that the antitumour efficacy of propranolol follows a U-shaped biphasic dose-response curve. Low doses (10 and 20 mg·kg^-1 ·day^-1 ) significantly inhibit tumour growth, whereas higher doses are progressively less effective. We also found that high-dose propranolol stimulates tumour arteriogenesis whereas no effect on angiogenesis was observed at any dose. Based on these data and considering that propranolol is a vasoactive drug, we hypothesized that it causes systemic vasoconstriction or vasodilation depending on the dose and thus alters tumour perfusion and growth. Consistent with this hypothesis, we found that propranolol has a biphasic effect on SVR with low and high doses producing vasoconstriction and vasodilation respectively.

CONCLUSIONS AND IMPLICATIONS

Propranolol inhibits melanoma growth in a U-shaped biphasic manner. A direct relationship exists between SVR and anti-melanoma activity.

The use of propranolol in the treatment of subglottic hemangiomas: A literature review and meta-analysis

OBJECTIVES

1) Describe the origins of the use of propranolol in the treatment of subglottic hemangiomas, 2) Perform meta-analysis of all case reports and series in which propranolol was used to treat subglottic hemangiomas.

STUDY DESIGN

Literature review and meta-analysis.

METHODS

A total of 61 cases were identified from 19 scholarly articles. Cases were assessed by parameters including age at diagnosis, presence of other hemangiomas, percent airway obstructed, dose of propranolol, treatment duration, age at therapy termination, use of steroids, and treatment failure. Treatment failure was defined as: 1) Need for surgery after initiation of propranolol, 2) Return of symptoms, or 3) Endoscopic worsening/recurrence of hemangioma. All data was subjected to comprehensive statistical analysis.

RESULTS

Though not statistically significant, a trend was noted towards a decreased treatment failure rate with increasing doses of propranolol (p = 0.0563). The use of concurrent steroids was associated with a higher failure rate (p = 0.0487). Notably, no associations were observed between the presence of additional hemangiomas, prior surgery, or increased initial percent airway obstruction with treatment failure.

CONCLUSION

Propranolol is rapidly becoming the standard of care in the treatment of subglottic hemangiomas. Despite widespread adoption, the rarity of this condition has limited previous studies to case reports and small series. No evidence-based guidelines exist for proper dosing of propranolol. The results of this meta-analysis suggest a benefit to higher doses of propranolol (3 mg/kg/day), though further investigation is needed.

Adrenergic signaling in heart failure and cardiovascular aging

Both cardiovascular disease and aging are associated with changes in the sympathetic nervous system. Indeed, mounting evidence indicates that adrenergic receptors are functionally involved in numerous processes underlying both aging and cardiovascular disorders, in particular heart failure. This article will review the pathophysiological role of the sympathetic nervous system in heart failure and cardiovascular aging.

DIFFUSE CHOROIDAL HEMANGIOMA MASQUERADING AS CENTRAL SEROUS CHORIORETINOPATHY TREATED WITH ORAL PROPRANOLOL

PURPOSE

To describe a case of diffuse choroidal hemangioma with exudative retinal detachment treated successfully with oral propranolol.

METHODS

Single interventional case report of a 14-year-old boy, known case of Sturge-Weber syndrome, presented with decreased vision in the right eye since 2 months. Presenting vision was finger-counting at 3 m. Examination revealed a neurosensory detachment at the macula clinically appearing like central serous chorioretinopathy. Fundus fluorescein angiogram, B-scan ultrasound, and optical coherence tomography were consistent with an underlying diffuse choroidal hemangioma with secondary exudative macular detachment. The patient could not afford radiotherapy and thus was treated with oral propranolol.

RESULTS

Serial clinical examinations and optical coherence tomographies showed gradual resolution of the subretinal fluid. Vision at the last visit 4 months after treatment was 6/9 best corrected.

CONCLUSION

Choroidal hemangioma can be mistaken clinically to be central serous chorioretinopathy. Oral propranolol is an effective and economical treatment option in patients not affording other standard modalities of treatment.

The β2-Adrenoceptor Agonist Terbutaline Stimulates Angiogenesis via Akt and ERK Signaling

Angiogenesis is associated with changes in endothelial cell (EC) proliferation and tube formation, controlled by extracellular receptor-activated kinase (ERK)/mitogen activated protein kinase (MAPK) and Akt signaling. Important regulators of these systems include hormones acting on G-protein-coupled receptors, such as beta 2-adrenoceptors (β2-ARs). In central nervous system (CNS) trauma, the importance of β2-AR modulation has been highlighted, although the effects on revascularization remain unclear. Vascular protection and revascularization are, however, key to support regeneration. We have investigated the angiogenic capacity of the specific β2-AR agonist terbutaline on ECs derived from the CNS, namely bEnd.3-cells. As angiogenesis is a multistep process involving increased proliferation and tube formation of ECs, we investigated the effects of terbutaline on these processes. We show that terbutaline significantly induced bEnd.3 tube formation in a matrigel in vitro assay. Moreover, administration of specific inhibitors of ERK and Akt signaling both inhibited terbutaline-induced tube formation. The proliferation rate of the ECs was not affected. In order to investigate the general effects of terbutaline in an organotypic system, we have used the chick chorioallantoic membrane (CAM)-assay. Most importantly, terbutaline increased the number of blood vessels in this in ovo setting. Although we observed a positive trend, the systemic administration of terbutaline did not significantly improve the functional outcome, nor did it affect revascularization in our spinal cord injury model. In conclusion, these data indicate that terbutaline is promising to stimulate blood vessel formation, underscoring the importance of further research into the angiotherapeutic relevance of terbutaline and β2-AR signaling after CNS-trauma. J. Cell. Physiol. 232: 298-308, 2017. © 2016 Wiley Periodicals, Inc.

Excellent response of infantile orofacio-orbital hemangioma to propranolol-pictorial depiction and literature review

Infantile hemangiomas (IHs) are common, benign vascular tumors of infancy, with more than half affecting the head and neck region. IHs involving the lips and oral cavity can often present to the oral surgeon and the pedodontist. Till date, several doubts exist among clinicians regarding the use of propranolol to treat infantile hemangiomas in neonates and small infants, appropriate dose, treatment duration, side effects, response, and long-term follow-up. We present a 2-month-old male infant with extensive hemangioma involving the face, orbit, buccal mucosa and palate with feeding difficulties, and risk of life-threatening complications such as airway compromise, aspiration, and visual loss which showed excellent response with high-dose propranolol and had no side effects. We also reviewed literature for the mechanism of action of propranolol and possible minor and serious side effects.

Overexpression of the β2AR gene improves function and re-endothelialization capacity of EPCs after arterial injury in nude mice

Background

Proliferation and migration of endothelial progenitor cells (EPCs) play important roles in restoring vascular injuries. β2 adrenergic receptors (β2ARs) are widely expressed in many tissues and have a beneficial impact on EPCs regulating neoangiogenesis. The aim of the present study was to determine the effect of overexpressing β2ARs in infused peripheral blood (PB)-derived EPCs on the re-endothelialization in injured vessels.

Methods

Induction of endothelial injury was performed in male nude mice that were subjected to wire-mediated injury to the carotid artery. Human PB-derived EPCs were transfected with an adenovirus serotype 5 vector expressing β2AR (Ad5/β2AR-EPCs) and were examined 48 h later. β2AR gene expression in EPCs was detected by real-time polymerase chain reaction and Western blot analysis. In vitro, the proliferation, migration, adhesion, and nitric oxide production of Ad5/β2AR-EPCs were measured. Meanwhile, phosphorylated Akt and endothelial nitric oxide synthase (eNOS), which are downstream of β2AR signaling, were also elevated. In an in vivo study, CM-DiI-labeled EPCs were injected intravenously into mice subjected to carotid injury. After 3 days, cells recruited to the injury sites were detected by fluorescent microscopy, and the re-endothelialization was assessed by Evans blue dye.

Results

In vitro, β2AR overexpression augmented EPC proliferation, migration, and nitric oxide production and enhanced EPC adhesion to endothelial cell monolayers. In vivo, when cell tracking was used, the number of recruited CM-DiI-labeled EPCs was significantly higher in the injured zone in mice transfused with Ad5/β2AR-EPCs compared with non-transfected EPCs. The degree of re-endothelialization was also higher in the mice transfused with Ad5/β2AR-EPCs compared with non-transfected EPCs. We also found that the phosphorylation of Akt and eNOS was increased in Ad5/β2AR-EPCs. Preincubation with β2AR inhibitor (ICI118,551), Akt inhibitor (ly294002), or eNOS inhibitor (L-NAME) significantly attenuated the enhanced in vitro function and in vivo re-endothelialization capacity of EPCs induced by β2AR overexpression.

Conclusions

The present study demonstrates that β2AR overexpression enhances EPC functions in vitro and enhances the vascular repair abilities of EPCs in vivo via the β2AR/Akt/eNOS pathway. Upregulation of β2AR gene expression through gene transfer may be a novel therapeutic target for endothelial repair.

Diabetic Macular Edema

Diabetic macular edema (DME), one the most prevalent causes of visual loss in industrialized countries, may be diagnosed at any stage of diabetic retinopathy. The diagnosis, treatment, and follow up of DME have become straightforward with recent developments in fundus imaging, such as optical coherence tomography. Laser photocoagulation, intravitreal injections, and pars plana vitrectomy surgery are the current treatment modalities; however, the positive effects of currently available intravitreally injected agents are temporary. At this point, further treatment choices are needed for a permanent effect.

Treatment of port wine stains with pulsed dye laser and topical timolol: a multicenter randomized controlled trial

BACKGROUND

Neoangiogenesis occurs within days following laser treatment of port wine stains (PWS), and plays a central role in treatment failures. Topical use of timolol can significantly reduce the production of vascular endothelial growth factor in vitro, and in animal models.

OBJECTIVES

The aim of this study was to assess the efficacy of topical timolol in combination with pulsed dye laser (PDL) treatment, compared with PDL alone, for treating PWS.

METHODS

This was a prospective multicenter controlled trial performed in children with PWS of the face who had not previously received laser treatment. After randomization, one group was treated with PDL alone, and the other with PDL followed by twice daily applications of timolol gel. Three laser sessions were performed at 1-month intervals with fixed parameters. The evaluation was performed on standardized pictures by two independent physicians blinded to the treatment received. The primary endpoint was marked or complete improvement of the PWS [Investigator Global Assessment (IGA) 3 or 4] 1 month after the third session.

RESULTS

Twenty-two children were included. Two patients were lost to follow-up. There was no difference in the success rate between the two groups (IGA 3 or 4 observed in one of 10 patients and two of 12 patients, for PDL alone, and for PDL associated with topical timolol, respectively; P = 1·0). No side-effect related to the application of topical timolol was observed.

CONCLUSIONS

The addition of timolol gel for preventing neoangiogenesis failed to significantly improve the efficacy of PDL treatment of PWS.

β Adrenergic Receptor Kinase C-Terminal Peptide Gene-Therapy Improves β2-Adrenergic Receptor-Dependent Neoangiogenesis after Hindlimb Ischemia

After hindlimb ischemia (HI), increased catecholamine levels within the ischemic muscle can cause dysregulation of β2-adrenergic receptor (β2AR) signaling, leading to reduced revascularization. Indeed, in vivo β2AR overexpression via gene therapy enhances angiogenesis in a rat model of HI. G protein-coupled receptor kinase 2 (GRK2) is a key regulator of βAR signaling, and β adrenergic receptor kinase C-terminal peptide (βARKct), a peptide inhibitor of GRK2, has been shown to prevent βAR down-regulation and to protect cardiac myocytes and stem cells from ischemic injury through restoration of β2AR protective signaling (i.e., protein kinase B/endothelial nitric oxide synthase). Herein, we tested the potential therapeutic effects of adenoviral-mediated βARKct gene transfer in an experimental model of HI and its effects on βAR signaling and on endothelial cell (EC) function in vitro. Accordingly, in this study, we surgically induced HI in rats by femoral artery resection (FAR). Fifteen days of ischemia resulted in significant βAR down-regulation that was paralleled by an approximately 2-fold increase in GRK2 levels in the ischemic muscle. Importantly, in vivo gene transfer of the βARKct in the hindlimb of rats at the time of FAR resulted in a marked improvement of hindlimb perfusion, with increased capillary and βAR density in the ischemic muscle, compared with control groups. The effect of βARKct expression was also assessed in vitro in cultured ECs. Interestingly, ECs expressing the βARKct fenoterol, a β2AR-agonist, induced enhanced β2AR proangiogenic signaling and increased EC function. Our results suggest that βARKct gene therapy and subsequent GRK2 inhibition promotes angiogenesis in a model of HI by preventing ischemia-induced β2AR down-regulation.

PHACE syndrome--clinical features, aetiology and management

PHACE syndrome comprises a spectrum of anomalies including posterior fossa malformations, haemangioma, arterial anomalies, cardiac defects and eye anomalies. PHACE should be considered in any patient with a large facial segmental infantile haemangioma (IH), and multidisciplinary management is crucial. Low-dose propranolol is effectively for the treatment of IH associated with PHACE syndrome. Recent evidence suggests IH is comprised of mesoderm-derived haemogenic endothelium.

CONCLUSION

The embryonic developmental anomaly nature of IH provides an insight into the origin of PHACE syndrome.

Autologous cell sources in therapeutic vasculogenesis: In vitro and in vivo comparison of endothelial colony-forming cells from peripheral blood and endothelial cells isolated from adipose tissue

BACKGROUND AIMS

Autologous endothelial cells are promising alternative angiogenic cell sources in trials of therapeutic vasculogenesis, in the treatment of vascular diseases and in the field of tissue engineering. A population of endothelial cells (ECs) with long-term proliferative capability, endothelial colony-forming cells (ECFCs), can be isolated from human peripheral blood. ECFCs are considered an endothelial precursor population. They can be expanded in cell factories in sufficient numbers for clinical applications, but because the number of isolated primary ECs is low, the culture period required may be long. Another EC population that is easily available in the autologous setting and may be expanded in vitro through several population doublings are ECs from adipose tissue (AT-ECs).

METHODS

Through extensive comparisons using whole-genome microarray analysis, morphology, phenotype and functional assays, we wanted to evaluate the potential of these EC populations for use in clinical neovascularization.

RESULTS

Global gene expression profiling of ECFCs, AT-ECs and the classical EC population, human umbilical vein ECs, showed that the EC populations clustered as unique populations, but very close to each other. By cell surface phenotype and vasculogenic potential in vitro and in vivo, we also found the ECFCs to be extremely similar to AT-ECs.

CONCLUSIONS

These properties, together with easy access in the autologous setting, suggest that both AT-ECs and ECFCs may be useful in trials of therapeutic neovascularization. However, AT-ECs may be a more practical alternative for obtaining large quantities of autologous ECs.

Novel method to assess arterial insufficiency in rodent hind limb

BACKGROUND

Lack of techniques to assess maximal blood flow capacity thwarts the use of rodent models of arterial insufficiency to evaluate therapies for intermittent claudication. We evaluated femoral vein outflow (VO) in combination with stimulated muscle contraction as a potential method to assess functional hind limb arterial reserve and therapeutic efficacy in a rodent model of subcritical limb ischemia.

MATERIALS AND METHODS

VO was measured with perivascular flow probes at rest and during stimulated calf muscle contraction in young, healthy rats (Wistar Kyoto, WKY; lean Zucker rats, LZR) and rats with cardiovascular risk factors (spontaneously hypertensive [SHR]; obese Zucker rats [OZR]) with acute and/or chronic femoral arterial occlusion. Therapeutic efficacy was assessed by administration of Ramipril or Losartan to SHR after femoral artery excision.

RESULTS

VO measurement in WKY demonstrated the utility of this method to assess hind limb perfusion at rest and during calf muscle contraction. Although application to diseased models (OZR and SHR) demonstrated normal resting perfusion compared with contralateral limbs, a significant reduction in reserve capacity was uncovered with muscle stimulation. Administration of Ramipril and Losartan demonstrated significant improvement in functional arterial reserve.

CONCLUSIONS

The results demonstrate that this novel method to assess distal limb perfusion in small rodents with subcritical limb ischemia is sufficient to unmask perfusion deficits not apparent at rest, detect impaired compensation in diseased animal models with risk factors, and assess therapeutic efficacy. The approach provides a significant advance in methods to investigate potential mechanisms and novel therapies for subcritical limb ischemia in preclinical rodent models.

Beta Adrenergic Signaling: A Targetable Regulator of Angiosarcoma and Hemangiosarcoma

Human angiosarcomas and canine hemangiosarcomas are highly aggressive cancers thought to arise from cells of vascular origin. The pathological features, morphological organization, and clinical behavior of canine hemangiosarcomas are virtually indistinct from those of human angiosarcomas. Overall survival with current standard-of-care approaches remains dismal for both humans and dogs, and each is likely to succumb to their disease within a short duration. While angiosarcomas in humans are extremely rare, limiting their study and treatment options, canine hemangiosarcomas occur frequently. Therefore, studies of these sarcomas in dogs can be used to advance treatment approaches for both patient groups. Emerging data suggest that angiosarcomas and hemangiosarcomas utilize beta adrenergic signaling to drive their progression by regulating the tumor cell niche and fine-tuning cellular responses within the tumor microenvironment. These discoveries indicate that inhibition of beta adrenergic signaling could serve as an Achilles heel for these tumors and emphasize the need to design therapeutic strategies that target tumor cell and stromal cell constituents. In this review, we summarize recent discoveries and present new hypotheses regarding the roles of beta adrenergic signaling in angiosarcomas and hemangiosarcomas. Because the use of beta adrenergic receptor antagonists is well established in human and veterinary medicine, beta blockade could provide an immediate adjunct therapy for treatment along with a tangible opportunity to improve upon the outcomes of both humans and dogs with these diseases.

Intravenous Followed by X-ray Fused with MRI-Guided Transendocardial Mesenchymal Stem Cell Injection Improves Contractility Reserve in a Swine Model of Myocardial Infarction

The aim of this study is to determine the effects of early intravenous (IV) infusion later followed by transendocardial (TE) injection of allogeneic mesenchymal stem cells (MSCs) following myocardial infarction (MI). Twenty-four swine underwent balloon occlusion reperfusion MI and were randomized into 4 groups: IV MSC (or placebo) infusion (post-MI day 2) and TE MSC (or placebo) injection targeting the infarct border with 2D X-ray fluoroscopy fused to 3D magnetic resonance (XFM) co-registration (post-MI day 14). Continuous ECG recording, MRI, and invasive pressure-volume analyses were performed. IV MSC plus TE MSC treated group was superior to other groups for contractility reserve (p = 0.02) and freedom from VT (p = 0.03) but had more lymphocytic foci localized to the peri-infarct region (p = 0.002). No differences were observed in post-MI remodeling parameters. IV followed by XFM targeted TE MSC therapy improves contractility reserve and suppresses VT but does not affect post-MI remodeling and may cause an immune response.

Biased signalling: the instinctive skill of the cell in the selection of appropriate signalling pathways

GPCRs (G-protein-coupled receptors) are members of a family of proteins which are generally regarded as the largest group of therapeutic drug targets. Ligands of GPCRs do not usually activate all cellular signalling pathways linked to a particular seven-transmembrane receptor in a uniform manner. The fundamental idea behind this concept is that each ligand has its own ability, while interacting with the receptor, to activate different signalling pathways (or a particular set of signalling pathways) and it is this concept which is known as biased signalling. The importance of biased signalling is that it may selectively activate biological responses to favour therapeutically beneficial signalling pathways and to avoid adverse effects. There are two levels of biased signalling. First, bias can arise from the ability of GPCRs to couple to a subset of the available G-protein subtypes: Gαs, Gαq/11, Gαi/o or Gα12/13. These subtypes produce the diverse effects of GPCRs by targeting different effectors. Secondly, biased GPCRs may differentially activate G-proteins or β-arrestins. β-Arrestins are ubiquitously expressed and function to terminate or inhibit classic G-protein signalling and initiate distinct β-arrestin-mediated signalling processes. The interplay of G-protein and β-arrestin signalling largely determines the cellular consequences of the administration of GPCR-targeted drugs. In the present review, we highlight the particular functionalities of biased signalling and discuss its biological effects subsequent to GPCR activation. We consider that biased signalling is potentially allowing a choice between signalling through ‘beneficial’ pathways and the avoidance of ‘harmful’ ones.

Gene therapy for cardiovascular disease: advances in vector development, targeting, and delivery for clinical translation

Gene therapy is a promising modality for the treatment of inherited and acquired cardiovascular diseases. The identification of the molecular pathways involved in the pathophysiology of heart failure and other associated cardiac diseases led to encouraging preclinical gene therapy studies in small and large animal models. However, the initial clinical results yielded only modest or no improvement in clinical endpoints. The presence of neutralizing antibodies and cellular immune responses directed against the viral vector and/or the gene-modified cells, the insufficient gene expression levels, and the limited gene transduction efficiencies accounted for the overall limited clinical improvements. Nevertheless, further improvements of the gene delivery technology and a better understanding of the underlying biology fostered renewed interest in gene therapy for heart failure. In particular, improved vectors based on emerging cardiotropic serotypes of the adeno-associated viral vector (AAV) are particularly well suited to coax expression of therapeutic genes in the heart. This led to new clinical trials based on the delivery of the sarcoplasmic reticulum Ca²⁺-ATPase protein (SERCA2a). Though the first clinical results were encouraging, a recent Phase IIb trial did not confirm the beneficial clinical outcomes that were initially reported. New approaches based on S100A1 and adenylate cyclase 6 are also being considered for clinical applications. Emerging paradigms based on the use of miRNA regulation or CRISPR/Cas9-based genome engineering open new therapeutic perspectives for treating cardiovascular diseases by gene therapy. Nevertheless, the continuous improvement of cardiac gene delivery is needed to allow the use of safer and more effective vector doses, ultimately bringing gene therapy for heart failure one step closer to reality.

p53-Induced inflammation exacerbates cardiac dysfunction during pressure overload

The rates of death and disability caused by severe heart failure are still unacceptably high. There is evidence that the sterile inflammatory response has a critical role in the progression of cardiac remodeling in the failing heart. The p53 signaling pathway has been implicated in heart failure, but the pathological link between p53 and inflammation in the failing heart is largely unknown. Here we demonstrate a critical role of p53-induced inflammation in heart failure. Expression of p53 was increased in cardiac endothelial cells and bone marrow cells in response to pressure overload, leading to up-regulation of intercellular adhesion molecule-1 (ICAM1) expression by endothelial cells and integrin expression by bone marrow cells. Deletion of p53 from endothelial cells or bone marrow cells significantly reduced ICAM1 or integrin expression, respectively, as well as decreasing cardiac inflammation and ameliorating systolic dysfunction during pressure overload. Conversely, overexpression of p53 in bone marrow cells led to an increase of integrin expression and cardiac inflammation that reduced systolic function. Norepinephrine markedly increased p53 expression in endothelial cells and macrophages. Reducing β2-adrenergic receptor expression in endothelial cells or bone marrow cells attenuated cardiac inflammation and improved systolic dysfunction during pressure overload. These results suggest that activation of the sympathetic nervous system promotes cardiac inflammation by up-regulating ICAM1 and integrin expression via p53 signaling to exacerbate cardiac dysfunction. Inhibition of p53-induced inflammation may be a novel therapeutic strategy for heart failure.

Regulation of β-adrenergic receptor trafficking and lung microvascular endothelial cell permeability by Rab5 GTPase

Rab5 GTPase modulates the trafficking of the cell surface receptors, including G protein-coupled β-adrenergic receptors (β-ARs). Here, we have determined the role of Rab5 in regulating the internalization of β-ARs in lung microvascular endothelial cells (LMECs) and in maintaining the integrity and permeability of endothelial cell barrier. Our data demonstrate that lipopolysaccharide (LPS) treatment disrupts LMEC barrier function and reduces the cell surface expression of β-ARs. Furthermore, the activation of β-ARs, particularly β2-AR, is able to protect the LMEC permeability from LPS injury. Moreover, siRNA-mediated knockdown of Rab5 inhibits both the basal and agonist-provoked internalization of β-ARs, therefore, enhancing the cell surface expression of the receptors and receptor-mediated ERK1/2 activation. Importantly, knockdown of Rab5 not only inhibits the LPS-induced effects on β-ARs but also protects the LMEC monolayer permeability. All together, these data provide strong evidence indicating a crucial role of Rab5-mediated internalization of β-ARs in functional regulation of LMECs.

The case for inhibiting p38 mitogen-activated protein kinase in heart failure

This minireview discusses the evidence that the inhibition of p38 mitogen-activated protein kinases (p38 MAPKs) maybe of therapeutic value in heart failure. Most previous experimental studies, as well as past and ongoing clinical trials, have focussed on the role of p38 MAPKs in myocardial infarction and acute coronary syndromes. There is now growing evidence that these kinases are activated within the myocardium of the failing human heart and in the heart and blood vessels of animal models of heart failure. Furthermore, from a philosophical viewpoint the chronic activation of the adaptive stress pathways that lead to the activation of p38 MAPKs in heart failure is analogous to the chronic activation of the sympathetic, renin-aldosterone-angiotensin and neprilysin systems. These have provided some of the most effective therapies for heart failure. This minireview questions whether similar and synergistic advantages would follow the inhibition of p38 MAPKs.

Effectiveness of propranolol in the treatment of infantile hemangioma beyond the proliferation phase

During the last 5 years, many studies have shown the efficacy of propranolol as first-line treatment for infantile hemangiomas (IHs), but not much has been written about the role of propranolol beyond the proliferation phase of IH (>1 year). Our aim was to assess propranolol efficacy and safety in the treatment of patients older than 1 year. A retrospective study of patients older than 1 year diagnosed with IH and treated in our vascular anomalies clinic between 2009 and 2013 was performed. Eighteen patients older than 1 year with a diagnosis of IH (15 girls, 3 boys) were identified. The mean age at the time of initiation of treatment was 25.7 months (range 13-72 mos). Single lesions were observed in 13 patients and multiple lesions in 5. Fifteen patients had focal lesions and three had segmental. The median duration of treatment with oral propranolol was 11.8 months (range 2-33 mos). Complete response was observed in 72.2% of the patients and partial response in 27.8%. Recurrence was observed in three patients 4.7 months after completion of therapy (range 0.3-8 mos). These patients required further therapy with propranolol for 6 more months. Bradycardia was documented in two patients and night terrors in one patient, which led to discontinuation of treatment. In our experience, propranolol may be useful in the treatment of IHs beyond the proliferation phase (>1 year old), but more studies are needed to support this observation.

Propranolol represses infantile hemangioma cell growth through the β2-adrenergic receptor in a HIF-1α-dependent manner

Propranolol, as a non-selective blocker of the β-adrenergic receptor (AR), is utilised as the first-line treatment for infantile hemangiomas. However, the underlying mechanism remains poorly understood. The present study was designed to investigate the molecular basis of propranolol on the regression of infantile hemangiomas using a proliferating infantile hemangioma-derived endothelial cell line. In infantile hemangioma patients, we found that propranolol significantly decreased the expression levels of the hypoxia inducible factor (HIF)-1α in serum and urine, as well as in hemangioma tissues. In vitro analysis revealed that propranolol reduces the expression of HIF-1α in hemangioma cells in a dose- and time-dependent manner, mainly by acting on β2-AR. Interestingly, it was observed that overexpression of HIF-1α apparently abrogated the inhibitory effects of propranolol on vascular endothelial growth factor (VEGF) expression and cell growth. Our data further demonstrated that propranolol inhibited the signal transducer and activator of transcription 3 (STAT3), a critical oncogenic signaling molecule, and the anti-apoptotic protein Bcl-2. Additionally, overexpression of HIF-1α significantly reversed the inhibitory effects of propranolol on STAT3 signaling. In a mouse xenograft hemangioma model, overexpression of HIF-1α significantly attenuated the therapeutic effects of propranolol and inhibited propranolol-induced hemangioma cell apoptosis. Moreover, the protein levels of VEGF, phosphorylated STAT3, total STAT3 and Bcl-2 were significantly upregulated by HIF-1α overexpression in propranolol-treated nude mice bearing hemangiomas. Collectively, our data provide evidence that propranolol may regress infantile hemangiomas by suppressing VEGF and STAT3 signaling pathways in an HIF-1α-dependent manner.

Pathological hypertrophy reverses β2-adrenergic receptor-induced angiogenesis in mouse heart

β-adrenergic activation and angiogenesis are pivotal for myocardial function but the link between both events remains unclear. The aim of this study was to explore the cardiac angiogenesis profile in a mouse model with cardiomyocyte-restricted overexpression of β₂-adrenoceptors (β₂-TG), and the effect of cardiac pressure overload. β₂-TG mice had heightened cardiac angiogenesis, which was essential for maintenance of the hypercontractile phenotype seen in this model. Relative to controls, cardiomyocytes of β₂-TGs showed upregulated expression of vascular endothelial growth factor (VEGF), heightened phosphorylation of cAMP-responsive-element-binding protein (CREB), and increased recruitment of phospho-CREB, CREB-binding protein (CBP), and p300 to the VEGF promoter. However, when hearts were subjected to pressure overload by transverse aortic constriction (TAC), angiogenic signaling in β₂-TGs was inhibited within 1 week after TAC. β₂-TG hearts, but not controls, exposed to pressure overload for 1–2 weeks showed significant increases from baseline in phosphorylation of Ca²⁺/calmodulin-dependent kinase II (CaMKIIδ) and protein expression of p53, reduction in CREB phosphorylation, and reduced abundance of phospho-CREB, p300 and CBP recruited to the CREB-responsive element (CRE) site of VEGF promoter. These changes were associated with reduction in both VEGF expression and capillary density. While non-TG mice with TAC developed compensatory hypertrophy, (₂-TGs exhibited exaggerated hypertrophic growth at week-1 post-TAC, followed by LV dilatation and reduced fractional shortening measured by serial echocardiography. In conclusion, angiogenesis was enhanced by the cardiomyocyte (₂AR/CREB/VEGF signaling pathway. Pressure overload rapidly inhibited this signaling, likely as a consequence of activated CaMKII and p53, leading to impaired angiogenesis and functional decompensation.