Vascular endothelial growth factors in cardiovascular medicine

Systematic review and meta-analysis of retinal microvascular caliber in bipolar disorder, major depressive disorder, and schizophrenia

BACKGROUND

Individuals with a severe mental illness (SMI), such as bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SZ), have increased rates of cardiovascular and cerebrovascular disease. Interestingly, it has been reported that retinal microvessels, a proxy cerebrovascular measure, non-invasively assessed via retinal imaging, predict future cardiovascular disease, with some studies also showing anomalous retinal microvascular caliber in SMI. Therefore, this review and meta-analysis evaluated whether retinal microvascular caliber differs between individuals with SMI vs controls and summarized current findings.

METHODS

A systematic literature search for retinal microvascular caliber and SMI was conducted in Embase and MEDLINE. Studies needed to be published in English before 2022 December 1st and examine retinal microvascular caliber in individuals diagnosed with a SMI. Finally, a meta-analysis of arteriolar and venular caliber in SMI case-controlled studies was also conducted.

RESULTS

The search yielded 65 unique articles, 11 were included in the review and 6 in the meta-analysis. The meta-analysis found that the SMI group had significantly wider venules than controls (SMD = -0.53; 95 % CI = 0.24, 0.81; p = 0.0004) but not arterioles (SMD = 0.07; 95 % CI = -0.29, 0.44; p = 0.70). Additionally, the systematic review found that poorer retinal microvascular health is associated with greater illness severity.

LIMITATIONS

Large heterogeneity of findings and small sample size.

CONCLUSION

This systematic review and meta-analysis found that SMI, specifically SZ, is associated with wider retinal venules. Retinal imaging, a fast, cost-effective, and non-invasive assay of cerebrovascular health, may provide insight into the pathophysiological processes of SMI. However, future longitudinal studies investigating these findings are warranted.

A genetic determinant of VEGF-A levels is associated with telomere attrition

Telomere length (TL) is a hallmark of cellular aging and is associated with chronic diseases development. The vascular endothelial growth factor A (VEGF-A), a potent angiogenesis factor, is implicated in the pathophysiology of many chronic diseases. The aim of the present study was to investigate the associations between VEGF-A and TL.

TL in leukocytes (LTL) and skeletal muscle (MTL) were measured, 10 VEGF-related polymorphisms genotyped, and VEGF-A plasma concentrations determined in 402 individuals from the TELARTA cohort. LTL/MTL ratio was calculated as an estimate of lifelong TL attrition. Associations between VEGF-A variants and levels, and TL parameters were investigated.

We identified one significant association between the minor allele (T) of rs6993770 variant and LTL/MTL ratio (P=0.001143, β=0.0148, SE=0.004516). The rs6993770 is an intronic variant of the ZFPM2 gene, which is involved in haematopoiesis and the identified association with increased telomere attrition could be due to increased haematopoiesis. No significant epistatic interaction was identified, and no association was found between levels of VEGF-A and any of assessed phenotypes.

We identified a potential common genetic regulation between VEGF-A and telomere length attrition that could be explained by mechanisms of increased hematopoiesis and production of platelets. VEGF-A and TL could play an important role in personalized medicine of chronic diseases and identification of molecular links between them can promote the understanding of their complex implications.

What Links an Increased Cardiovascular Risk and Inflammatory Bowel Disease? A Narrative Review

Several studies have shown increased rates of cardiovascular disease (CVD) in patients suffering from inflammatory bowel disease (IBD), particularly in cases of early atherosclerosis and myocardial infarction. IBD most frequently begins at an early age, patients usually present normal weight and remain under constant care of a physician, as well as of a nutritionist. Therefore, the classical risk factors of CVD are not reflected in the higher prevalence of CVD in the IBD population. Still, both groups are characterised by chronic inflammation and display similar physiopathological mechanisms. In the course of IBD, increased concentrations of pro-inflammatory cytokines, such as C-reactive protein (CRP) and homocysteine, may lead to endothelial dysfunctions and the development of CVD. Furthermore, gut microbiota dysbiosis in patients with IBD also constitutes a risk factor for an increased susceptibility to cardiovascular disease and atherosclerosis. Additionally, diet is an essential factor affecting both positively and negatively the course of the aforementioned diseases, whereas several dietary patterns may also influence the association between IBD and CVD. Thus, it is essential to investigate the factors responsible for the increased cardiovascular (CV) risk in this group of patients. Our paper attempts to review the role of potential inflammatory and nutritional factors, as well as intestinal dysbiosis and pharmacotherapy, in the increased risk of CVD in IBD patients.

Beyond Growth Factors: Macrophage-Centric Strategies for Angiogenesis

Functional angiogenesis is a critical therapeutic goal in many pathological conditions. Logically, the use of pro-angiogenic growth factors has been the mainstay approach despite obvious limitations and modest success. Recently, macrophages have been identified as key regulators of the host response to implanted materials. Particularly, our understanding of dynamically plastic macrophage phenotypes, their interactions with biomaterials, and varied roles in different stages of angiogenic processes is evolving rapidly. In this review, we discuss changing perspectives on therapeutic angiogenesis, in relation to implantable materials and macrophage-centric strategies therein. Harnessing the different mechanisms through which the macrophage-driven host response is involved in angiogenesis has great potential for improving clinical outcome.

Elastin-Based Materials: Promising Candidates for Cardiac Tissue Regeneration

Stroke and cardiovascular episodes are still some of the most common diseases worldwide, causing millions of deaths and costing billions of Euros to healthcare systems. The use of new biomaterials with enhanced biological and physical properties has opened the door to new approaches in cardiovascular applications. Elastin-based materials are biomaterials with some of the most promising properties. Indeed, these biomaterials have started to yield good results in cardiovascular and angiogenesis applications. In this review, we explore the latest trends in elastin-derived materials for cardiac regeneration and the different possibilities that are being explored by researchers to regenerate an infarcted muscle and restore its normal function. Elastin-based materials can be processed in different manners to create injectable systems or hydrogel scaffolds that can be applied by simple injection or as patches to cover the damaged area and regenerate it. Such materials have been applied to directly regenerate the damaged cardiac muscle and to create complex structures, such as heart valves or new bio-stents that could help to restore the normal function of the heart or to minimize damage after a stroke. We will discuss the possibilities that elastin-based materials offer in cardiac tissue engineering, either alone or in combination with other biomaterials, in order to illustrate the wide range of options that are being explored. Moreover, although tremendous advances have been achieved with such elastin-based materials, there is still room for new approaches that could trigger advances in cardiac tissue regeneration.

Mending a broken heart: current strategies and limitations of cell-based therapy

The versatility of pluripotent stem cells, attributable to their unlimited self-renewal capacity and plasticity, has sparked a considerable interest for potential application in regenerative medicine. Over the past decade, the concept of replenishing the lost cardiomyocytes, the crux of the matter in ischemic heart disease, with pluripotent stem cell-derived cardiomyocytes (PSC-CM) has been validated with promising pre-clinical results. Nevertheless, clinical translation was hemmed in by limitations such as immature cardiac properties, long-term engraftment, graft-associated arrhythmias, immunogenicity, and risk of tumorigenicity. The continuous progress of stem cell-based cardiac therapy, incorporated with tissue engineering strategies and delivery of cardio-protective exosomes, provides an optimistic outlook on the development of curative treatment for heart failure. This review provides an overview and current status of stem cell-based therapy for heart regeneration, with particular focus on the use of PSC-CM. In addition, we also highlight the associated challenges in clinical application and discuss the potential strategies in developing successful cardiac-regenerative therapy.

Involvement of Heparanase in Endothelial Cell-Cardiomyocyte Crosstalk

Traditionally, the management of diabetes has focused mainly on controlling high blood glucose levels. Unfortunately, despite valiant efforts to normalize this blood glucose, poor medication management predisposes these patients to heart failure. Following diabetes, how the heart utilizes different sources of fuel for energy is key to the development of heart failure. The diabetic heart switches from using both glucose and fats, to predominately using fats as an energy resource for maintaining its activities. This transformation to using fats as an exclusive source of energy is helpful in the initial stages of the disease and is tightly controlled. However, over the progression of diabetes, there is a loss of this controlled supply and use of fats, which ultimately has terrible consequences since the uncontrolled use of fats produces toxic by-products which weaken heart function and cause heart disease. Heparanase is a key player that directs how much fats are provided to the heart and does so in association with several partners like LPL and VEGFs. Together, they regulate the amount of fats supplied, and their subsequent breakdown to provide energy. Following diabetes, there is a disruption in this network resulting in fat oversupply and cell death. Understanding how the heparanase-LPL-VEGFs "ensemble" cooperates, and its dysfunction in the diabetic heart would be useful in restoring metabolic equilibrium and limiting diabetes-related cardiac damage.

Perspectives on Using Platelet-Rich Plasma and Platelet-Rich Fibrin for Managing Patients with Critical Lower Limb Ischemia After Partial Foot Amputation

The problem of lower limb preservation with symptoms of critical ischemia, resulting in necrosis of the distal foot portion, remains open. These cases require solving few tactical questions, such as the primary revascularization method, limb-preserving amputation, stimulation of regeneration, and finally, determining the criteria for auto-dermal transplantation. We analyzed 29 patient cases with critical lower limb ischemia of fourth grade, according to the Fontaine classification (or the sixth category according to Rutherford's classification), who underwent partial foot amputation due to dry gangrene and were threated using PRGF®-ENDORET® platelet-rich plasma and platelet-rich fibrin technology. The control group was comprised of 21 patients who received traditional postoperative wound treatment. All patients went through a combination of transluminal revascularization and platelet-rich plasma to create a "therapeutic" neoangiogenic effect. Indications for these procedures were severe distal arterial occlusion and stenosis. Using transluminal procedures with platelet-rich plasma therapy improves the blood perfusion to the distal portions of the limb in patients with critical ischemia in a short time, which is an informative diagnostic criterion for wound healing after amputation. Plasmatic membranes create an optimal environment for tissue regeneration, thus reducing the wound closure time using an auto-dermal transplant.

Tethering QK peptide to enhance angiogenesis in elastin-like recombinamer (ELR) hydrogels

The development of new capillary networks in engineered constructs is essential for their survival and their integration with the host tissue. It has recently been demonstrated that ELR-based hydrogels encoding different bioactivities are able to modulate their interaction with the host after injection or implantation, as indicated by an increase in cell adhesion and the ability to trigger vascularization processes. Accordingly, the aim of this study was to increase their angiogenic ability both in vitro and in vivo using a small VEGF mimetic peptide named QK, which was tethered chemically to ELR-based hydrogels containing cell-adhesion sequences in their backbone, such as REDV and RGD, as well as a proteolytic site (VGVAPG). In vitro studies were performed using a co-culture of endothelial and fibroblast cells encapsulated into the ELR-based hydrogels in order to determine cell proliferation after 21 days of culture, as well as the number of cell-cell interactions. It was found that although the presence of this peptide does not influence the morphological and rheological properties of these hydrogels, it has an effect on cell behaviour, inducing an increase in cell proliferation and the formation of endothelial cell clusters. In vivo studies demonstrate that the QK peptide enhances the formation of prominent functional capillaries at three weeks post-injection, as confirmed by H&E staining and CD31 immunohistochemistry. The newly formed functional microvasculature ensures perfusion and connection with surrounding tissues. These results show that ELR-QK hydrogels increase capillary network formation and are therefore attractive candidates for application in tissue regeneration, for example for the treatment of cardiovascular diseases such as myocardial infarction or ischemia.

Comparison of Angiogenic Activities of Three Neuropeptides, Substance P, Secretoneurin, and Neuropeptide Y Using Myocardial Infarction

BACKGROUND

The interplay between neurogenesis and angiogenesis is crucial during the development mediated by neuro-angiogenic morphogens. In particular, the angiogenic activity of neuropeptides and their role in tissue regeneration have long been investigated for better understanding of their biological mechanisms and further applications. However, there have been few studies for direct comparison of angiogenic activities of neuropeptides for in vitro and in vivo models. In this study, we report that direct comparison of the angiogenic activities of neuropeptide Y, secretoneurin, and substance P (SP) immobilized on hydrogels in in vitro and in vivo experiments.

METHODS

A hyaluronic acid-based hydrogel is prepared by utilizing acrylated hyaluronic acid and thiolated peptides as a crosslinker and angiogenic factors, respectively. Angiogenic activities of three neuropeptides are evaluated not only by in vitro angiogenic and gene expression assays, but also by an in vivo chronic myocardial infarction model.

RESULTS

The comparison of in vitro angiogenic activities of three peptides demonstrates that the SP-immobilized hydrogel shows a higher degree of cell network formation and angiogenic-specific genes than those of the other peptides and the control case. In addition, a three-dimensional angiogenic assay illustrates that more sprouting is observable in the SP group. Evaluation of regenerative activity in the chronic myocardial infarction model reveals that all three peptide-immobilized hydrogels induce increased cardiac function as well as structural regeneration. Among all the cases, the SP group provided the highest regenerative activity both in vitro and in vivo.

CONCLUSION

In our comparison study, the SP-immobilized hydrogel shows the highest angiogenic activity and tissue regeneration among the test groups. This result suggests that nerve regeneration factors help angiogenesis in damaged tissues, which also highlights the importance of the neuro-angiogenic peptides as an element of tissue regeneration.

Effect of hydrochlorothiazide on serum uric acid concentration: a genome-wide association study

AIM

To recognize genetic associations of hydrochlorothiazide-induced change in serum uric acid (SUA) concentration.

PATIENTS & METHODS

We conducted a genome-wide association study on hydrochlorothiazide-induced change in SUA in 214 Finnish men from the GENRES study. Replication analyses were performed in 465 Finns from the LIFE study.

RESULTS

In GENRES, we identified 31 loci associated with hydrochlorothiazide-induced change in SUA at p < 5 × 10^-5. rs1002976 near VEGFC associated with the change in GENRES and in LIFE. rs950569 near BRINP3 associated with the change in SUA in GENRES and LIFE. The analysis of previously reported SNPs and candidate genes provided some proof for PADI4 and ABCC4.

CONCLUSION

We report genetic markers that may predict the increase in SUA concentration during thiazide treatment.

Risk of cardiovascular disease in inflammatory bowel disease

Cardiovascular disease (CVD) can arise because of chronic inflammation and inflammatory bowel disease (IBD) is one such disease where the risk for CVD and eventual heart failure is increased considerably. The incidence of IBD, which refers to both ulcerative colitis and Crohn's disease, has been on the increase in several countries and is a potential risk factor for CVD. Although IBD can potentially cause venous thromboembolism, its significance in arterial stiffening, atherosclerosis, ischemic heart disease and myocardial infarction is only being realized now and it is currently under debate. However, several studies with large groups of patients have demonstrated the association of IBD with heart disease. It has been suggested that systemic inflammation as observed in IBD patients leads to oxidative stress and elevated levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), which lead to phenotypic changes in smooth muscle cells and sets into motion a series of events that culminate in atherosclerosis and CVD. Besides the endogenous factors and cytokines, it has been suggested that due to the compromised intestinal mucosal barrier, endotoxins and bacterial lipopolysaccharides produced by intestinal microflora can enter into circulation and activate inflammatory responses that lead to atherosclerosis. Therapeutic management of IBD-associated heart diseases cannot be achieved with simple anti-inflammatory drugs such as corticosteroids and anti-TNF-α antibodies. Treatment with existing medications for CVDs, aspirin, platelet aggregation inhibitors and statins is found to be acceptable and safe. Nevertheless, further research is needed to assess their efficacy in IBD patients suffering from heart disease.

Regenerative pharmacology: recent developments and future perspectives

This review focuses on the current status of research that utilizes the application of pharmacological sciences to accelerate, optimize and characterize the development, maturation and function of bioengineered and regenerating tissues. These regenerative pharmacologic approaches have been applied to diseases of the urogenital tract, the heart, the brain, the musculoskeletal system and diabetes. Approaches have included the use of growth factors (such as VEGF and chemokines (stromal-derived factor – CXCL12) to mobilize cell to the sights of tissue loss or damage. The promise of this approach is to bypass the lengthy and expensive processes of cell isolation and implant fabrication to stimulate the body to heal itself with its own tissue regenerative pathways.

Cardiac Regeneration using Growth Factors: Advances and Challenges

Myocardial infarction is the most significant manifestation of ischemic heart disease and is associated with high morbidity and mortality. Novel strategies targeting at regenerating the injured myocardium have been investigated, including gene therapy, cell therapy, and the use of growth factors. Growth factor therapy has aroused interest in cardiovascular medicine because of the regeneration mechanisms induced by these biomolecules, including angiogenesis, extracellular matrix remodeling, cardiomyocyte proliferation, stem-cell recruitment, and others. Together, these mechanisms promote myocardial repair and improvement of the cardiac function. This review aims to address the strategic role of growth factor therapy in cardiac regeneration, considering its innovative and multifactorial character in myocardial repair after ischemic injury. Different issues will be discussed, with emphasis on the regeneration mechanisms as a potential therapeutic resource mediated by growth factors, and the challenges to make these proteins therapeutically viable in the field of cardiology and regenerative medicine. Resumo O infarto do miocárdio representa a manifestação mais significativa da cardiopatia isquêmica e está associado a elevada morbimortalidade. Novas estratégias vêm sendo investigadas com o intuito de regenerar o miocárdio lesionado, incluindo a terapia gênica, a terapia celular e a utilização de fatores de crescimento. A terapia com fatores de crescimento despertou interesse em medicina cardiovascular, devido aos mecanismos de regeneração induzidos por essas biomoléculas, incluindo angiogênese, remodelamento da matriz extracelular, proliferação de cardiomiócitos e recrutamento de células-tronco, dentre outros. Em conjunto, tais mecanismos promovem a reparação do miocárdio e a melhora da função cardíaca. Esta revisão pretende abordar o papel estratégico da terapia, com fatores de crescimento, para a regeneração cardíaca, considerando seu caráter inovador e multifatorial sobre o reparo do miocárdio após dano isquêmico. Diferentes questões serão discutidas, destacando-se os mecanismos de regeneração como recurso terapêutico potencial mediado por fatores de crescimento e os desafios para tornar essas proteínas terapeuticamente viáveis no âmbito da cardiologia e da medicina regenerativa.

Endothelial cell-cardiomyocyte crosstalk in diabetic cardiomyopathy

The incidence of diabetes is increasing globally, with cardiovascular disease accounting for a substantial number of diabetes-related deaths. Although atherosclerotic vascular disease is a primary reason for this cardiovascular dysfunction, heart failure in patients with diabetes might also be an outcome of an intrinsic heart muscle malfunction, labelled diabetic cardiomyopathy. Changes in cardiomyocyte metabolism, which encompasses a shift to exclusive fatty acid utilization, are considered a leading stimulus for this cardiomyopathy. In addition to cardiomyocytes, endothelial cells (ECs) make up a significant proportion of the heart, with the majority of ATP generation in these cells provided by glucose. In this review, we will discuss the metabolic machinery that drives energy metabolism in the cardiomyocyte and EC, its breakdown following diabetes, and the research direction necessary to assist in devising novel therapeutic strategies to prevent or delay diabetic heart disease.

Cardiovascular complications in inflammatory bowel disease

Over the past years, a growing number of studies have indicated that patients suffering from inflammatory bowel disease (IBD) have an increased risk of developing cardiovascular disease. Both are chronic inflammatory diseases and share certain pathophysiological mechanisms that may influence each other. High levels of cytokines, C-reactive protein (CRP), and homocysteine in IBD patients may lead to endothelial dysfunction, an early sign of atherosclerosis. IBD patients, in general, do not show the typical risk factors for cardiovascular disease but changes in lipid profiles similar to the ones seen in cardiovascular events have been reported recently. Higher levels of coagulation factors frequently occur in IBD which may predispose to arterial thromboembolic events. Finally, the gut itself may have an impact on atherogenesis during IBD through its microbiota. Microbial products are released from the inflamed mucosa into the circulation through a leaky barrier. The induced rise in proinflammatory cytokines could contribute to endothelial damage, artherosclerosis and cardiovascular events. Although large retrospective studies favor a link between IBD and cardiovascular diseases, the mechanisms behind still remain to be determined.

Cardiovascular complications in inflammatory bowel disease

Over the past years, a growing number of studies have indicated that patients suffering from inflammatory bowel disease (IBD) have an increased risk of developing cardiovascular disease. Both are chronic inflammatory diseases and share certain pathophysiological mechanisms that may influence each other. High levels of cytokines, C-reactive protein (CRP), and homocysteine in IBD patients may lead to endothelial dysfunction, an early sign of atherosclerosis. IBD patients, in general, do not show the typical risk factors for cardiovascular disease but changes in lipid profiles similar to the ones seen in cardiovascular events have been reported recently. Higher levels of coagulation factors frequently occur in IBD which may predispose to arterial thromboembolic events. Finally, the gut itself may have an impact on atherogenesis during IBD through its microbiota. Microbial products are released from the inflamed mucosa into the circulation through a leaky barrier. The induced rise in proinflammatory cytokines could contribute to endothelial damage, artherosclerosis and cardiovascular events. Although large retrospective studies favor a link between IBD and cardiovascular diseases, the mechanisms behind still remain to be determined.

Relationships between vascular endothelial growth factor levels and temperament and character inventory traits in healthy Japanese subjects

BACKGROUND AND AIM

Personality traits and vascular endothelial growth factor (VEGF) levels are both independently correlated with major depressive disorder and depressive mood. However, no studies have reported associations between personality traits and VEGF levels. Thus, we hypothesized that there is a correlation between the results of the Temperament and Character Inventory (TCI) and VEGF levels.

METHODS

We investigated 179 healthy participants who completed the TCI. We collected a serum sample from each subject and measured each participant's VEGF level by an enzyme-linked immunosorbent assay (ELISA). Simple and multiple regression analyses were performed to examine the correlations between the scores on the seven TCI dimensions and several other factors, including gender, age and VEGF level.

RESULTS

A total of 150 subjects completed the examination. Among the dimensions of the TCI, the harm avoidance (HA) scores were negatively correlated with VEGF levels, but there were no significant correlations between the scores for any other dimensions and VEGF levels. The HA score was significantly correlated with sex, age and VEGF level, and single and multiple regression analyses yielded the same results.

CONCLUSION

VEGF may be associated with certain personality factors. This study is the first to demonstrate a direct association between VEGF levels and a dimension of the TCI in healthy subjects.

Enhancing the efficacy of mesenchymal stem cell therapy

Mesenchymal stem cell (MSC) therapy is entering a challenging phase after completion of many preclinical and clinical trials. Among the major hurdles encountered in MSC therapy are inconsistent stem cell potency, poor cell engraftment and survival, and age/disease-related host tissue impairment. The recognition that MSCs primarily mediate therapeutic benefits through paracrine mechanisms independent of cell differentiation provides a promising framework for enhancing stem cell potency and therapeutic benefits. Several MSC priming approaches are highlighted, which will likely allow us to harness the full potential of adult stem cells for their future routine clinical use.

Heart regeneration with engineered myocardial tissue

Heart disease is the leading cause of morbidity and mortality worldwide, and regenerative therapies that replace damaged myocardium could benefit millions of patients annually. The many cell types in the heart, including cardiomyocytes, endothelial cells, vascular smooth muscle cells, pericytes, and cardiac fibroblasts, communicate via intercellular signaling and modulate each other's function. Although much progress has been made in generating cells of the cardiovascular lineage from human pluripotent stem cells, a major challenge now is creating the tissue architecture to integrate a microvascular circulation and afferent arterioles into such an engineered tissue. Recent advances in cardiac and vascular tissue engineering will move us closer to the goal of generating functionally mature tissue. Using the biology of the myocardium as the foundation for designing engineered tissue and addressing the challenges to implantation and integration, we can bridge the gap from bench to bedside for a clinically tractable engineered cardiac tissue.

Cell therapy, 3D culture systems and tissue engineering for cardiac regeneration

Ischemic Heart Disease (IHD) still represents the "Number One Killer" worldwide accounting for the death of numerous patients. However the capacity for self-regeneration of the adult heart is very limited and the loss of cardiomyocytes in the infarcted heart leads to continuous adverse cardiac-remodeling which often leads to heart-failure (HF). The concept of regenerative medicine comprising cell-based therapies, bio-engineering technologies and hybrid solutions has been proposed as a promising next-generation approach to address IHD and HF. Numerous strategies are under investigation evaluating the potential of regenerative medicine on the failing myocardium including classical cell-therapy concepts, three-dimensional culture techniques and tissue-engineering approaches. While most of these regenerative strategies have shown great potential in experimental studies, the translation into a clinical setting has either been limited or too rapid leaving many key questions unanswered. This review summarizes the current state-of-the-art, important challenges and future research directions as to regenerative approaches addressing IHD and resulting HF.

Thioredoxin-interacting protein expression is required for VEGF-mediated angiogenic signal in endothelial cells

AIMS

Thioredoxin-interacting protein (TXNIP) contributes to cellular redox-state homeostasis via binding and inhibiting thioredoxin (TRX). Increasing evidence suggests that cellular redox homeostasis regulates vascular endothelial growth factor (VEGF)-mediated signaling. This study aims to examine the redox-dependant role of TXNIP in regulating VEGF-mediated S-glutathionylation and angiogenic signaling. TXNIP-knockout mice (TKO) or wild-type (WT) treated with the reduced glutathione (GSH)-precursor, N-acetyl cysteine (WT-NAC, 500 mg/kg) were compared to WT using hypoxia-induced neovascularization model.

RESULTS

In response to hypoxia, retinas from TKO and WT-NAC mice showed significant decreases in reparative revascularization and pathological neovascularization with similar VEGF expression compared with WT. VEGF failed to stimulate vascular sprouting from aortic rings of TKO compared to WT mice. TKO mice or WT+NAC experienced reductive stress as indicated by twofold increase in TRX reductase activity and fourfold increase in reduced-GSH levels compared with WT. In human microvascular endothelial (HME) cells, VEGF stimulated co-precipitation between vascular endothelial growth factor receptor 2 (VEGFR2) with low molecular weight protein tyrosine phosphatase (LMW-PTP). Silencing TXNIP expression blunted VEGF-induced oxidation of GSH and S-glutathionylation of the LMW-PTP in HME cells. These effects were associated with impaired VEGFR2 phosphorylation that culminated in inhibiting cell migration and tube formation. Overexpression of TXNIP restored VEGFR2 phosphorylation and cell migration in TKO-endothelial cells.

INNOVATION

TXNIP expression is required for VEGF-mediated VEGFR2 activation and angiogenic response in vivo and in vitro. TXNIP expression regulates VEGFR-2 phosphorylation via S-glutathionylation of LMW-PTP in endothelial cells.

CONCLUSION

Our results provide novel mechanistic insight into modulating TXNIP expression as a potential therapeutic target in diseases characterized by aberrant angiogenesis.

A comparative study of NONOate based NO donors: spermine NONOate is the best suited NO donor for angiogenesis

Nitric oxide (NO) is a known modulator of angiogenesis. The NONOate subfamily of NO donors has long been used in experimental and clinical studies to promote angiogenesis. However, no studies have been conducted yet to compare the angiogenesis potential of these NO donors in respect to their pattern of NO release. We hypothesize that having different pattern of NO release, each of the NO donors in NONOate subfamily can promote key stages of angiogenesis in differential manner. To verify our hypothesis, NO donors with half life ranging from seconds to several hours and having very different pattern of NO release were selected to evaluate their efficacy in modulating angiogenesis. Endothelial tube formation using EAhy926 cells was maximally increased by Spermine NONOate (SP) treatment. SP treatment maximally induced both ex vivo and in vivo angiogenesis using egg yolk and cotton plug angiogenesis models respectively. Experiment using chick embryo partial ischemia model revealed SP as the best suited NO donor to recover ischemia driven hampered angiogenesis. The present study elaborated that differential release pattern of NO by different NO donors can modulate angiogenesis differentially and also suggested that SP have a unique pattern of NO release that best fits for angiogenesis.

Identification of protein biomarkers associated with cardiac ischemia by a proteomic approach

Angina is chest pain induced by ischemia of the heart muscle, generally due to obstruction or spasm of the coronary arteries. People that suffer from average to severe cases of angina have an increased percentage of death before the age of 55, usually around 60%. Therefore, prevention of major complications, optimizing diagnosis, prognosis and therapeutics are of primary importance. The main objective of this study was to uncover biomarkers by comparing serum protein profiles of patients suffering from stable or unstable angina and controls. We identified by non-targeted proteomic approach and confirmed by the means of independent techniques, the differential expression of several proteins indicating significantly increased vascular inflammation response, disturbance in the lipid metabolism and in atherogenic plaques stability.

Peripheral vascular endothelial growth factor level is associated with antidepressant treatment response: results of a preliminary study

BACKGROUND

Recent investigations have revealed multiple actions of vascular endothelial growth factor (VEGF) in the nervous system. The role of VEGF in the molecular background of mood disorders has also been proposed. In this study we were interested in investigating a possible association between VEGF levels and treatment response in patients with a current episode of major depression (MDE).

METHODS

34 patients with MDE were enrolled in our study. Depressive symptoms were monitored by the Montgomery-Åsberg Depression Rating Scale at baseline (V(1)) and after a 4-week treatment period (V(2)). Patients with less than a 50% improvement in MADRS total scores during this period were regarded as non-responders.

RESULTS

Plasma VEGF levels did not change during the treatment period in either the total sample or in the responder and non-responder subsamples. There was a strong trend for higher baseline VEGF levels in the non-responder group than in the responder group (p=0.055) and this difference-as a weak trend-was still detectable at the end of the treatment period (p=0.097). Regression analysis revealed that the baseline VEGF level was a significant predictor for the endpoint MADRS score (p=0.02).

LIMITATIONS

Sample size was relatively small; sample consists of both patients with MDD and bipolar disorder.

CONCLUSIONS

Our preliminary results raise the possibility that baseline levels of peripheral VEGF may predict treatment response in patients with mood disorders. Considering the limitations of our study, further investigations should resolve whether VEGF is a useful biomarker for treatment response in depression in clinical practice.

Transcatheter based electromechanical mapping guided intramyocardial transplantation and in vivo tracking of human stem cell based three dimensional microtissues in the porcine heart

Stem cells have been repeatedly suggested for cardiac regeneration after myocardial infarction (MI). However, the low retention rate of single cell suspensions limits the efficacy of current therapy concepts so far. Taking advantage of three dimensional (3D) cellular self-assembly prior to transplantation may be beneficial to overcome these limitations. In this pilot study we investigate the principal feasibility of intramyocardial delivery of in-vitro generated stem cell-based 3D microtissues (3D-MTs) in a porcine model. 3D-MTs were generated from iron-oxide (MPIO) labeled human adipose-tissue derived mesenchymal stem cells (ATMSCs) using a modified hanging-drop method. Nine pigs (33 ± 2 kg) comprising seven healthy ones and two with chronic MI in the left ventricle (LV) anterior wall were included. The pigs underwent intramyocardial transplantation of 16 × 10(3) 3D-MTs (1250 cells/MT; accounting for 2 × 10(7) single ATMSCs) into the anterior wall of the healthy pigs (n = 7)/the MI border zone of the infarcted (n = 2) of the LV using a 3D NOGA electromechanical mapping guided, transcatheter based approach. Clinical follow-up (FU) was performed for up to five weeks and in-vivo cell-tracking was performed using serial magnet resonance imaging (MRI). Thereafter, the hearts were harvested and assessed by PCR and immunohistochemistry. Intramyocardial transplantation of human ATMSC based 3D-MTs was successful in eight animals (88.8%) while one pig (without MI) died during the electromechanical mapping due to sudden cardiac-arrest. During FU, no arrhythmogenic, embolic or neurological events occurred in the treated pigs. Serial MRI confirmed the intramyocardial presence of the 3D-MTs by detection of the intracellular iron-oxide MPIOs during FU. Intramyocardial retention of 3D-MTs was confirmed by PCR analysis and was further verified on histology and immunohistochemical analysis. The 3D-MTs appeared to be viable, integrated and showed an intact micro architecture. We demonstrate the principal feasibility and safety of intramyocardial transplantation of in-vitro generated stem cell-based 3D-MTs. Multimodal cell-tracking strategies comprising advanced imaging and in-vitro tools allow for in-vivo monitoring and post-mortem analysis of transplanted 3D-MTs. The concept of 3D cellular self-assembly represents a promising application format as a next generation technology for cell-based myocardial regeneration.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.

Investigation of circulating endothelial progenitor cells and angiogenic and inflammatory cytokines during recovery from an episode of major depression

BACKGROUND

Epidemiological studies strongly suggest a bidirectional positive relationship between mood and cardiovascular disorders (CVD). Reduced numbers of circulating endothelial progenitor cells (cEPCs) are associated with elevated risks of CVD. Previously we demonstrated that patients with a current episode of major depression (MDE) have a decreased number of cEPCs. The role of vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF) has been demonstrated in the etiopathogenesis of depression. In addition these cytokines are also involved in regulation of the vascular system. This suggests that VEGF and/or TNF may also mediate the elevated risk of CVD associated with mood disorders.

METHODS

In the current investigation, which has a self-controlled study design, we examined changes in VEGF and TNF levels and--for the first time--changes in cEPC number during recovery from MDE.

RESULTS

Twenty-four patients with MDE were enrolled. The severity of their depressive symptoms improved significantly during the one-month treatment period (~50% decrease in MADRS score; P≤0.001). We did not find significant differences between baseline and end-point levels of VEGF, TNF and the number of cEPCs.

CONCLUSION

Our negative result for alteration in the number of cEPCs in the course of recovery from MDE raises several questions. Before discarding the number of cEPCs as a possible marker of depression--and/or elevated CV risk associated with it--our results would require confirmation in larger samples. Our results for TNF and VEGF do not contradict the findings of prior studies, since these were controversial.

Therapeutic applications of mesenchymal stromal cells: paracrine effects and potential improvements

Among the various types of cell-to-cell signaling, paracrine signaling comprises those signals that are transmitted over short distances between different cell types. In the human body, secreted growth factors and cytokines instruct, among others, proliferation, differentiation, and migration. In the hematopoietic stem cell (HSC) niche, stromal cells provide instructive cues to stem cells via paracrine signaling and one of these cell types, known to secrete a broad panel of growth factors and cytokines, is mesenchymal stromal cells (MSCs). The factors secreted by MSCs have trophic, immunomodulatory, antiapoptotic, and proangiogenic properties, and their paracrine profile varies according to their initial activation by various stimuli. MSCs are currently studied as treatment for inflammatory diseases such as graft-versus-host disease and Crohn's disease, but also as treatment for myocardial infarct and solid organ transplantation. In addition, MSCs are investigated for their use in tissue engineering applications, in which their differentiation plays an important role, but as we have recently demonstrated, their trophic factors may also be involved. Furthermore, a functional improvement of MSCs might be obtained after preconditioning or tailoring the cells themselves. Also, the way the cells are clinically administered may be specialized for specific therapeutic scenarios. In this review we will first discuss the HSC niche, in which MSCs were recently identified and are thought to play an instructive and supportive role. We will then evaluate therapeutic applications that currently try to utilize the trophic and/or immunomodulatory properties of MSCs, and we will also discuss new options to enhance their therapeutic effects.

A two-compartment model of VEGF distribution in the mouse

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis – the growth of new microvessels from existing microvasculature. Angiogenesis is a complex process involving numerous molecular species, and to better understand it, a systems biology approach is necessary. In vivo preclinical experiments in the area of angiogenesis are typically performed in mouse models; this includes drug development targeting VEGF. Thus, to quantitatively interpret such experimental results, a computational model of VEGF distribution in the mouse can be beneficial. In this paper, we present an in silico model of VEGF distribution in mice, determine model parameters from existing experimental data, conduct sensitivity analysis, and test the validity of the model.

The multiscale model is comprised of two compartments: blood and tissue. The model accounts for interactions between two major VEGF isoforms (VEGF₁₂₀ and VEGF₁₆₄) and their endothelial cell receptors VEGFR-1, VEGFR-2, and co-receptor neuropilin-1. Neuropilin-1 is also expressed on the surface of parenchymal cells. The model includes transcapillary macromolecular permeability, lymphatic transport, and macromolecular plasma clearance. Simulations predict that the concentration of unbound VEGF in the tissue is approximately 50-fold greater than in the blood. These concentrations are highly dependent on the VEGF secretion rate. Parameter estimation was performed to fit the simulation results to available experimental data, and permitted the estimation of VEGF secretion rate in healthy tissue, which is difficult to measure experimentally. The model can provide quantitative interpretation of preclinical animal data and may be used in conjunction with experimental studies in the development of pro- and anti-angiogenic agents. The model approximates the normal tissue as skeletal muscle and includes endothelial cells to represent the vasculature. As the VEGF system becomes better characterized in other tissues and cell types, the model can be expanded to include additional compartments and vascular elements.

Intramuscular VEGF activates an SDF1-dependent progenitor cell cascade and an SDF1-independent muscle paracrine cascade for cardiac repair

The skeletal muscle is endowed with an impressive ability to regenerate after injury, and this ability is coupled to paracrine production of many trophic factors possessing cardiovascular benefits. Taking advantage of this humoral capacity of the muscle, we recently demonstrated an extracardiac therapeutic regimen based on intramuscular delivery of VEGF-A(165) for repair of the failing hamster heart. This distal organ repair mechanism activates production from the injected hamstring of many trophic factors, among which stromal-derived factor-1 (SDF1) prominently mobilized multi-lineage progenitor cells expressing CXCR4 and their recruitment to the heart. The mobilized bone marrow progenitor cells express the cardiac transcription factors myocyte enhancer factor 2c and GATA4 and several major trophic factors, most notably IGF1 and VEGF. SDF1 blockade abrogated myocardial recruitment of CXCR4(+) and c-kit(+) progenitor cells with an insignificant effect on the hematopoietic progenitor lineage. The knockdown of cardiac progenitor cells led to deprivation of myocardial trophic factors, resulting in compromised cardiomyogenesis and angiogenesis. However, the VEGF-injected hamstring continued to synthesize cardioprotective factors, contributing to moderate myocardial tissue viability and function even in the presence of SDF1 blockade. These findings thus uncover two distinct but synergistic cardiac therapeutic mechanisms activated by intramuscular VEGF. Whereas the SDF1/CXCR4 axis activates the progenitor cell cascade and its trophic support of cardiomyogenesis intramuscularly, VEGF amplifies the skeletal muscle paracrine cascade capable of directly promoting myocardial survival independent of SDF1. Given that recent clinical trials of cardiac repair based on the use of marrow-mobilizing agents have been disappointing, the proposed dual therapeutic modality warrants further investigation.

Stem cells for cardiac repair: status, mechanisms, and new strategies

Faced with the end stage of heart disease, the current treatments only slow worsening of heart failure. Stem cells have the potential of self-renewal and differentiation. It is expected to replace and repair damaged myocardium. But many clinical trials have shown that the stem cell therapy of heart failure is modest or not effective. The possible causes for the limited effects of stem cell in curing heart failure are the stem cells which have been transplanted into the ischemic heart muscle may suffer low survival rate, affected by inflammatory molecules, proapoptotic factor, and lack of nutrients and oxygen, and then the stem cells which home and have been completely transplanted to the site of myocardial infarction become very small. Therefore, through preconditioning of stem cells and appropriate choice of genes for mesenchymal stem cell modification to improve the survival rate of stem cells, ability in homing and promoting angiogenesis may become the newly effective strategies for the application of stem cells therapy in heart failure.

Placental growth factor regulates cardiac adaptation and hypertrophy through a paracrine mechanism

RATIONALE

Paracrine growth factor-mediated crosstalk between cardiac myocytes and nonmyocytes in the heart is critical for programming adaptive cardiac hypertrophy in which myocyte size, capillary density, and the extracellular matrix function coordinately.

OBJECTIVE

To examine the role that placental growth factor (PGF) plays in the heart as a paracrine regulator of cardiac adaptation to stress stimulation.

METHODS AND RESULTS

PGF is induced in the heart after pressure-overload stimulation, where it is expressed in both myocytes and nonmyocytes. We generated cardiac-specific and adult inducible PGF-overexpressing transgenic mice and analyzed Pgf(-/-) mice to examine the role that this factor plays in cardiac disease and paracrine signaling. Although PGF transgenic mice did not have a baseline phenotype or a change in capillary density, they did exhibit a greater cardiac hypertrophic response, a greater increase in capillary density, and increased fibroblast content in the heart in response to pressure-overload stimulation. PGF transgenic mice showed a more adaptive type of cardiac growth that was protective against signs of failure with pressure overload and neuroendocrine stimulation. Antithetically, Pgf(-/-) mice rapidly died of heart failure within 1 week of pressure overload, they showed an inability to upregulate angiogenesis, and they showed significantly less fibroblast activity in the heart. Mechanistically, we show that PGF does not have a direct effect on cardiomyocytes but works through endothelial cells and fibroblasts by inducing capillary growth and fibroblast proliferation, which secondarily support greater cardiac hypertrophy through intermediate paracrine growth factors such as interleukin-6.

CONCLUSIONS

PGF is a secreted factor that supports hypertrophy and cardiac function during pressure overload by affecting endothelial cells and fibroblasts that in turn stimulate and support the myocytes through additional paracrine factors.

Regulation of vulnerable plaque development by the heme oxygenase/carbon monoxide system

Plaque rupture and luminal thrombosis is the most common cause of coronary occlusion that leads to acute coronary syndromes. High-risk plaques, or vulnerable plaques, are defined as lesions that are prone to rupture, also known as thin cap fibroatheroma (TCFA), or lesions prone to erosion or with calcified cores. This review will focus mainly on the vulnerable plaque, which is thought to be the precursor of the thrombogenic or ruptured plaque. Heme oxygenase 1 (HO-1) protein expression is specifically increased in lesions with a vulnerable plaque phenotype resembling TCFAs and correlates with a rise in expression levels of intimal proinflammatory markers. Data from several human and animal studies imply an important function for HO-1 in the genetic regulation of early, as well as late atherogenesis, and plaque destabilization toward a vulnerable phenotype. Although a direct association between HO-1, vulnerable plaque development, and clinical outcome is for now missing, the correlations that have been reported for HO-1 and coronary artery disease point to a possible link.

Adrenomedullin augments the angiogenic potential of late outgrowth endothelial progenitor cells

The therapeutic utility of endothelial progenitor cells (EPCs) in cardiovascular disease is potentially hampered by their low numbers in the circulation, impaired functional activity, and inhibitory factors in the recipient. These obstacles can possibly be circumvented by the use of proangiogenic cytokines and peptides. We sought to examine the effect of the endogenous vasoactive peptide adrenomedullin (AM) on the angiogenic potential of late outgrowth EPCs and their release of proangiogenic and proinflammatory cytokines/chemokines. Human peripheral blood mononuclear cells were cultured until the appearance of typical late outgrowth EPC colonies. The effect of AM on EPC proliferation was assessed using a colorimetric MTS proliferation assay while differentiation and formation of tubular structures in an EPC/fibroblast coculture or matrigel assay was used to assess the angiogenic potential of the cells. Finally, the release and mRNA transcripts of cytokines/chemokines were quantified in stimulated vs. nonstimulated EPCs using real-time PCR and a bead-based multiplex assay. The cultured EPCs possessed an endothelial phenotype and expressed the AM receptor (calcitonin receptor-like receptor/receptor activity modifying protein-2). AM stimulation induced proliferation of EPCs compared with controls ( P < 0.05). Furthermore, AM produced a 36% and 80% increase in the formation of tubular networks in the EPC/fibroblast coculture and matrigel assay, respectively ( P < 0.05). These effects seemed to be mediated through the phosphatidylinositol 3-kinase/Akt signaling pathway. AM did not seem to significantly influence the release or production of IL-6, IL-8, VEGF, stromal cell-derived factor 1, or the expression of CXCR-4 or VEGF receptor 2. In conclusion, adrenomedullin augmented the growth and angiogenic properties of late outgrowth EPCs, but did not influence their paracrine properties.

Myocardial tolerance to ischemia-reperfusion injury, training intensity and cessation

Training has been shown to induce cardioprotection. The mechanisms involved remain still poorly understood. Aims of the study were to examine the relevance of training intensity on myocardial protection against ischemia/reperfusion (I/R) injury, and to which extent the beneficial effects persist after training cessation in rats. Sprague-Dawley rats trained at either low (60% [Formula: see text]) or high (80% [Formula: see text]) intensity for 10 weeks. An additional group of highly trained rats was detrained for 4 weeks. Untrained rats served as controls. At the end of treatment, rats of all groups were split into two subgroups. In the former, rats underwent left anterior descending artery (LAD) ligature for 30 min, followed by 90-min reperfusion, with subsequent measurement of the infarct size. In the latter, biopsies were taken to measure heat-shock proteins (HSP) 70/72, vascular endothelial growth factor (VEGF) protein levels, and superoxide dismutase (SOD) activity. Training reduced infarct size proportionally to training intensity. With detraining, infarct size increased compared to highly trained rats, maintaining some cardioprotection with respect to controls. Cardioprotection was proportional to training intensity and related to HSP70/72 upregulation and Mn-SOD activity. The relationship with Mn-SOD was lost with detraining. VEGF protein expression was not affected by either training or detraining. Stress proteins and antioxidant defenses might be involved in the beneficial effects of long-term training as a function of training intensity, while HSP70 may be one of the factors accounting for the partial persistence of myocardial protection against I/R injury in detrained rats.

Activation of host tissue trophic factors through JAK-STAT3 signaling: a mechanism of mesenchymal stem cell-mediated cardiac repair

We recently demonstrated a cardiac therapeutic regimen based on injection of bone marrow mesenchymal stem cells (MSCs) into the skeletal muscle. Although the injected MSCs were trapped in the local musculature, the extracardiac cell delivery approach repaired the failing hamster heart. This finding uncovers a tissue repair mechanism mediated by trophic factors derived from the injected MSCs and local musculature that can be explored for minimally invasive stem cell therapy. However, the trophic factors involved in cardiac repair and their actions remain largely undefined. We demonstrate here a role of MSC-derived IL-6-type cytokines in cardiac repair through engagement of the skeletal muscle JAK-STAT3 axis. The MSC IL-6-type cytokines activated JAK-STAT3 signaling in cultured C2C12 skeletal myocytes and caused increased expression of the STAT3 target genes hepatocyte growth factor (HGF) and VEGF, which was inhibited by glycoprotein 130 (gp130) blockade. These in vitro findings were corroborated by in vivo studies, showing that the MSC-injected hamstrings exhibited activated JAK-STAT3 signaling and increased growth factor/cytokine production. Elevated host tissue growth factor levels were also detected in quadriceps, liver, and brain, suggesting a possible global trophic effect. Paracrine actions of these host tissue-derived factors activated the endogenous cardiac repair mechanisms in the diseased heart mediated by Akt, ERK, and JAK-STAT3. Administration of the cell-permeable JAK-STAT inhibitor WP1066 abrogated MSC-mediated host tissue growth factor expression and functional improvement. The study illustrates that the host tissue trophic factor network can be activated by MSC-mediated JAK-STAT3 signaling for tissue repair.

Chlorthalidone Decreases Platelet Aggregation and Vascular Permeability and Promotes Angiogenesis

Variations in diuretic-mediated inhibition of carbonic anhydrase-dependent chloride transport in platelets and vascular smooth muscle could account for the contrasting efficacy of the thiazide and thiazide-like diuretics in reducing cardiovascular morbidity in patients with hypertension. We assessed platelet carbonic anhydrase activity and catecholamine-induced platelet aggregation in the presence of a thiazide and a “thiazide-like” inhibitor of the sodium-chloride cotransporter. Individual variation in platelet carbonic anhydrase activity correlated with contrasting sensitivity to epinephrine-mediated platelet aggregation. Both chlorthalidone, which potently inhibits platelet carbonic anhydrase, and bendroflumethiazide, which has much less effect on this enzyme, increased the amount of epinephrine needed to induce platelet aggregation when compared with the absence of a diuretic. However, chlorthalidone was significantly more effective than bendroflumethiazide in reducing epinephrine-mediated platelet aggregation. Chlorthalidone also induced marked changes in the number of gene transcripts for two proteins that mediate angiogenesis and vascular permeability, vascular endothelial growth factor C and transforming growth factor-β3; chlorthalidone and bendroflumethiazide had contrasting effects on the expression of vascular endothelial growth factor C. Chlorthalidone and bendroflumethiazide reduced vascular permeability to albumin, but only chlorthalidone increased angiogenesis. Thiazides and thiazide-like diuretics can comparably reduce blood pressure, but the drugs in this class are not all alike. It can be suggested from our findings that thiazide and thiazide-like diuretics vary in their pleiotropic effects on platelets and in the vasculature, and these differences could explain the contrasting ability of these drugs to reduce cardiovascular morbidity despite comparable reduction in blood pressure.

Host tissue response in stem cell therapy

Preclinical and clinical trials of stem cell therapy have been carried out for treating a broad spectrum of diseases using several types of adult stem cells. While encouraging therapeutic results have been obtained, much remains to be investigated regarding the best cell type to use, cell dosage, delivery route, long-term safety, clinical feasibility, and ultimately treatment cost. Logistic aspects of stem cell therapeutics remain an area that requires urgent attention from the medical community. Recent cardiovascular trial studies have demonstrated that growth factors and cytokines derived from the injected stem cells and host tissue appear to contribute largely to the observed therapeutic benefits, indicating that trophic actions rather than the multilineage potential (or stemness) of the administered stem cells may provide the underlying tissue healing power. However, the capacity for trophic factor production can be aberrantly downregulated as seen in human heart disease. Skeletal muscle is a dynamic tissue with an impressive ability to continuously respond to environmental stimuli. Indeed, a relation exists between active skeletal muscle and low cardiovascular risk, highlighting the critical link between the skeletal muscle and cardiovascular systems. Adding to this notion are recent studies showing that stem cells injected into skeletal muscle can rescue the failing rodent heart through activation of the muscle trophic factor network and mobilization of bone marrow multilineage progenitor cells. However, aging and disease can adversely affect the host tissue into which stem cells are injected. A better understanding of the host tissue response in stem cell therapy is necessary to advance the field and bridge the gap between preclinical and clinical findings.

Vascular endothelial growth factor: an essential component of angiogenesis and fracture healing

Fractures require adequate stability and blood supply to heal. The vascular supply to long bones is compromised in a fracture, and the ability to heal hinges on the ability of new blood vessels to proliferate from surrounding vessels in a process known as angiogenesis. This process is largely driven by the growth factor, vascular endothelial growth factor (VEGF), whose levels are increased locally and systemically during fracture healing. VEGF is involved in many steps throughout the fracture healing cascade, from initially being concentrated in fracture hematoma, to the promotion of bone turnover during the final remodeling phase. This article reviews the current literature surrounding the role of VEGF and other growth factors in reestablishing vascular supply to fractured bone, as well as medications and surgical techniques that may inhibit this process.

A systems biology perspective on sVEGFR1: its biological function, pathogenic role and therapeutic use

Angiogenesis is the growth of new capillaries from pre-existent microvasculature. A wide range of pathological conditions, from atherosclerosis to cancer, can be attributed to either excessive or deficient angiogenesis. Central to the physiological regulation of angiogenesis is the vascular endothelial growth factor (VEGF) system – its ligands and receptors (VEGFRs) are thus prime molecular targets of pro-angiogenic and anti-angiogenic therapies. Of growing interest as a prognostic marker and therapeutic target in angiogenesis-dependent diseases is soluble VEGF receptor-1 (sVEGFR1, also known as sFlt-1) – a truncated version of the cell membrane-spanning VEGFR1. For instance, it is known that sVEGFR1 is involved in the endothelial dysfunction characterizing the pregnancy disorder of pre-eclampsia, and sVEGFR1’s therapeutic potential as an anti-angiogenic agent is being evaluated in pre-clinical models of cancer. This mini review begins with an examination of the protein domain structure and biomolecular interactions of sVEGFR1 in relation to the full-length VEGFR1. A synopsis of known and inferred physiological and pathological roles of sVEGFR1 is then given, with emphasis on the utility of computational systems biology models in deciphering the molecular mechanisms by which sVEGFR1’s purported biological functions occur. Finally, we present the need for a systems biology perspective in interpreting circulating VEGF and sVEGFR1 concentrations as surrogate markers of angiogenic status in angiogenesis-dependent diseases.

Vascular endothelial growth factor (VEGF) as a key therapeutic trophic factor in bone marrow mesenchymal stem cell-mediated cardiac repair

We recently demonstrated a novel effective therapeutic regimen for treating hamster heart failure based on injection of bone marrow mesenchymal stem cells (MSCs) or MSC-conditioned medium into the skeletal muscle. The work highlights an important cardiac repair mechanism mediated by the myriad of trophic factors derived from the injected MSCs and local musculature that can be explored for non-invasive stem cell therapy. While this therapeutic regimen provides the ultimate proof that MSC-based cardiac repair is mediated by the trophic actions independent of MSC differentiation or stemness, the trophic factors responsible for cardiac regeneration after MSC therapy remain largely undefined. Toward this aim, we took advantage of the finding that human and porcine MSCs exhibit species-related differences in expression of trophic factors. We demonstrate that human MSCs when compared to porcine MSCs express and secrete 5-fold less vascular endothelial growth factor (VEGF) in conditioned medium (40+/-5 and 225+/-17 pg/ml VEGF, respectively). This deficit in VEGF output was associated with compromised cardiac therapeutic efficacy of human MSC-conditioned medium. Over-expression of VEGF in human MSCs however completely restored the therapeutic potency of the conditioned medium. This finding indicates VEGF as a key therapeutic trophic factor in MSC-mediated myocardial regeneration, and demonstrates the feasibility of human MSC therapy using trophic factor-based cell-free strategies, which can eliminate the concern of potential stem cell transformation.

Intramuscular VEGF repairs the failing heart: role of host-derived growth factors and mobilization of progenitor cells

Skeletal muscle produces a myriad of mitogenic factors possessing cardiovascular regulatory effects that can be explored for cardiac repair. Given the reported findings that VEGF may modulate muscle regeneration, we investigated the therapeutic effects of chronic injections of low doses of human recombinant VEGF-A(165) (0.1-1 microg/kg) into the dystrophic hamstring muscle in a hereditary hamster model of heart failure and muscular dystrophy. In vitro, VEGF stimulated proliferation, migration, and growth factor production of cultured C2C12 skeletal myocytes. VEGF also induced production of HGF, IGF2, and VEGF by skeletal muscle. Analysis of skeletal muscle revealed an increase in myocyte nuclear [531 +/- 12 VEGF 1 microg/kg vs. 364 +/- 19 for saline (number/mm(2)) saline] and capillary [591 +/- 80 VEGF 1 microg/kg vs. 342 +/- 21 for saline (number/mm(2))] densities. Skeletal muscle analysis revealed an increase in Ki67(+) nuclei in the VEGF 1 microg/kg group compared with saline. In addition, VEGF mobilized c-kit(+), CD31(+), and CXCR4(+) progenitor cells. Mobilization of progenitor cells was consistent with higher SDF-1 concentrations found in hamstring, plasma, and heart in the VEGF group. Echocardiogram analysis demonstrated improvement in left ventricular ejection fraction (0.60 +/- 0.02 VEGF 1 microg/kg vs. 0.45 +/- 0.01 mm for saline) and an attenuation in ventricular dilation [5.59 +/- 0.12 VEGF 1 microg/kg vs. 6.03 +/- 0.09 for saline (mm)] 5 wk after initiating therapy. Hearts exhibited higher cardiomyocyte nuclear [845 +/- 22 VEGF 1 microg/kg vs. 519 +/- 40 for saline (number/mm(2))] and capillary [2,159 +/- 119 VEGF 1 microg/kg vs. 1,590 +/- 66 for saline (number/mm(2))] densities. Myocardial analysis revealed approximately 2.5 fold increase in Ki67+ cells and approximately 2.8-fold increase in c-kit(+) cells in the VEGF group, which provides evidence for cardiomyocyte regeneration and progenitor cell expansion. This study provides novel evidence of a salutary effect of VEGF in the cardiomyopathic hamster via induction of myogenic growth factor production by skeletal muscle and mobilization of progenitor cells, which resulted in attenuation of cardiomyopathy and repair of the heart.

In vivo properties of the proangiogenic peptide QK

The main regulator of neovascularization is Vascular Endothelial Growth Factor (VEGF). We recently demonstrated that QK, a de novo engineered VEGF mimicking peptide, shares in vitro the same biological properties of VEGF, inducing capillary formation and organization. On these grounds, the aim of this study is to evaluate in vivo the effects of this small peptide. Therefore, on Wistar Kyoto rats, we evaluated vasomotor responses to VEGF and QK in common carotid rings. Also, we assessed the effects of QK in three different models of angiogenesis: ischemic hindlimb, wound healing and Matrigel plugs. QK and VEGF present similar endothelium-dependent vasodilatation. Moreover, the ability of QK to induce neovascularization was confirmed us by digital angiographies, dyed beads dilution and histological analysis in the ischemic hindlimb as well as by histology in wounds and Matrigel plugs. Our findings show the proangiogenic properties of QK, suggesting that also in vivo this peptide resembles the full VEGF protein. These data open to new fields of investigation on the mechanisms of activation of VEGF receptors, offering clinical implications for treatment of pathophysiological conditions such as chronic ischemia.