Reduced pericardial levels of endostatin correlate with collateral development in patients with ischemic heart disease

Developments in Extracellular Matrix-Based Angiogenesis Therapy for Ischemic Heart Disease: A Review of Current Strategies, Methodologies and Future Directions

Ischemic heart disease (IHD) is the leading cause of mortality worldwide, underscoring the urgent need for innovative therapeutic strategies. The cardiac extracellular matrix (ECM) undergoes extreme transformations during IHD, adversely influencing the heart's structure, mechanics, and cellular signaling. Researchers investigating the regenerative capacity of the diseased heart have turned their attention to exploring the modulation of ECM to improve therapeutic outcomes. In this review, we thoroughly examine the current state of knowledge regarding the cardiac ECM and its therapeutic potential in the ischemic myocardium. We begin by providing an overview of the fundamentals of cardiac ECM, focusing on the structural, functional, and regulatory mechanisms that drive its modulation. Subsequently, we examine the ECM's interactions within both chronically ischemic and acutely infarcted myocardium, emphasizing key ECM components and their roles in modulating angiogenesis. Finally, we discuss recent ECM-based approaches in biomedical engineering, focusing on different types of scaffolds as delivery tools and their compositions, and conclude with future directions for therapeutic research. By harnessing the potential of these emerging ECM-based therapies, we aim to contribute to the development of novel therapeutic modalities for IHD.

Collagen 18A1/Endostatin Expression in the Progression of Right Ventricular Remodeling and Dysfunction in Pulmonary Arterial Hypertension

Numerous studies have demonstrated that endostatin (ES), a potent angiostatic peptide derived from collagen type XVIII α 1 chain and encoded by COL18A1, is elevated in pulmonary arterial hypertension (PAH). It is important to note that elevated ES has consistently been associated with altered hemodynamics, poor functional status, and adverse outcomes in adult and pediatric PAH. This study used serum samples from patients with Group I PAH and plasma and tissue samples derived from the Sugen/hypoxia rat pulmonary hypertension model to define associations between COL18A1/ES and disease development, including hemodynamics, right ventricle (RV) remodeling, and RV dysfunction. Using cardiac magnetic resonance imaging and advanced hemodynamic assessments with pressure-volume loops in patients with PAH to assess RV-pulmonary arterial coupling, we observed a strong relationship between circulating ES levels and metrics of RV structure and function. Specifically, RV mass and the ventricular mass index were positively associated with ES, whereas RV ejection fraction and RV-pulmonary arterial coupling were inversely associated with ES levels. Our animal data demonstrate that the development of pulmonary hypertension is associated with increased COL18A1/ES in the heart as well as the lungs. Disease-associated increases in COL18A1 mRNA and protein were most pronounced in the RV compared with the left ventricle and lung. COL18A1 expression in the RV was strongly associated with disease-associated changes in RV mass, fibrosis, and myocardial capillary density. These findings indicate that COL18A1/ES increases early in disease development in the RV and implicates COL18A1/ES in pathologic RV dysfunction in PAH.

Circulatory endostatin level and risk of cardiovascular events in patients with end-stage renal disease on hemodialysis

BACKGROUND

Endostatin is released during extracellular matrix remodeling and is involved in the development of vascular pathology and cardiovascular (CV) disease. However, the role of circulating endostatin as a biomarker of vascular calcification and CV events in patients undergoing hemodialysis (HD) remains unclear.

METHODS

A total of 372 patients undergoing HD were prospectively recruited. Plasma endostatin levels were measured at baseline, and their associations with circulating mineral bone disease (MBD) biomarkers and abdominal aortic vascular calcification scores were analyzed. The primary endpoint was defined as a composite of CV and cardiac events.

RESULTS

Plasma levels of patients in endostatin tertile 3 were significantly associated with low-density lipoprotein cholesterol levels and predialysis systolic blood pressure in multivariate analysis. However, endostatin levels did not correlate with circulating MBD biomarkers or vascular calcification scores. Patients in endostatin tertile 3 had a significantly higher cumulative event rate for the composite of CV events (p = 0.006). Endostatin tertile 3 was also associated with an increased cumulative rate of cardiac events (p = 0.04). In multivariate Cox regression analyses, endostatin tertile 3 was associated with a 4.37-fold risk for composite CV events and a 3.88-fold risk for cardiac events after adjusting for multiple variables.

CONCLUSION

Higher circulating endostatin levels were independently associated with atherosclerotic risk factors but did not correlate with MBD markers or vascular calcification. Higher circulating endostatin levels were associated with a greater risk of composite CV events in patients undergoing HD, and endostatin is a biomarker that helps to determine the high risk of CV events.

Uric acid to high-density lipoprotein cholesterol ratio predicts adverse cardiovascular events in patients with coronary chronic total occlusion

BACKGROUND AND AIMS

Uric acid to high-density lipoprotein cholesterol ratio (UHR) is a novel index of metabolism and inflammation proposed by recent studies. The prognostic value of UHR is undetermined in patients with coronary chronic total occlusion (CTO). The aim of this study was to investigate the association of UHR with adverse cardiovascular events in patients with CTO.

METHODS AND RESULTS

In this retrospective cohort study, we enrolled 566 patients with CTO lesion in our hospital from January 2016 to December 2019. Patients were divided into three groups based on UHR level. The primary endpoint was major adverse cardiovascular event (MACE), defined as a combination of death, non-fatal MI, target vessel revascularization (TVR), and non-fatal stroke. The median follow-up time of this study was 43 months. During the follow-up, 107 (18.9%) MACEs were recorded. Kaplan-Meier survival plots show the cumulative incidence of MACE-free decreased across tertile of UHR (log-rank test, p < 0.001). In the fully adjusted model, the Hazard ratio (95% CI) of MACE was 2.16 (1.17-3.99) in tertile 3 and 2.01 (1.62-2.49) for per SD increase in UHR.

CONCLUSION

Elevated UHR predicts an increasing risk of MACE in patients with CTO. UHR is a simple and reliable indicator for risk stratification and early intervention in CTO patients.

Endostatin in Renal and Cardiovascular Diseases

Endostatin, a protein derived from the cleavage of collagen XVIII by the action of proteases, is an endogenous inhibitor known for its ability to inhibit proliferation and migration of endothelial cells, angiogenesis, and tumor growth. Angiogenesis is defined as the formation of new blood vessels from pre-existing vasculature, which is crucial in many physiological processes, such as embryogenesis, tissue regeneration, and neoplasia.

SUMMARY

Increasing evidence shows that dysregulation of angiogenesis is crucial for the pathogenesis of renal and cardiovascular diseases. Endostatin plays a pivotal role in the regulation of angiogenesis. Recent studies have provided evidence that circulating endostatin increases significantly in patients with kidney and heart failure and may also contribute to disease progression.

KEY MESSAGE

In the current review, we summarize the latest findings on preclinical and clinical studies analyzing the impact of endostatin on renal and cardiovascular diseases.

The angiostatic peptide endostatin enhances mortality risk prediction in pulmonary arterial hypertension

Currently available noninvasive markers for assessing disease severity and mortality risk in pulmonary arterial hypertension (PAH) are unrelated to fundamental disease biology. Endostatin, an angiostatic peptide known to inhibit pulmonary artery endothelial cell migration, proliferation and survival in vitro, has been linked to adverse haemodynamics and shortened survival in small PAH cohorts. This observational cohort study sought to assess: 1) the prognostic performance of circulating endostatin levels in a large, multicentre PAH cohort; and 2) the added value gained by incorporating endostatin into existing PAH risk prediction models. Endostatin ELISAs were performed on enrolment samples collected from 2017 PAH subjects with detailed clinical data, including survival times. Endostatin associations with clinical variables, including survival, were examined using multivariable regression and Cox proportional hazards models. Extended survival models including endostatin were compared to null models based on the REVEAL risk prediction tool and European Society of Cardiology/European Respiratory Society (ESC/ERS) low-risk criteria using likelihood ratio tests, Akaike and Bayesian information criteria and C-statistics. Higher endostatin was associated with higher right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance, and with shorter 6-min walk distance (p<0.01). Mortality risk doubled for each log higher endostatin (hazard ratio 2.3, 95% CI 1.6-3.4, p<0.001). Endostatin remained an independent predictor of survival when incorporated into existing risk prediction models. Adding endostatin to REVEAL-based and ESC/ERS criteria-based risk assessment strategies improved mortality risk prediction. Endostatin is a robust, independent predictor of mortality in PAH. Adding endostatin to existing PAH risk prediction strategies improves PAH risk assessment.

Basement Membrane Extracellular Matrix Proteins in Pulmonary Vascular and Right Ventricular Remodeling in Pulmonary Hypertension

The extracellular matrix (ECM), a highly organized network of structural and nonstructural proteins, plays a pivotal role in cellular and tissue homeostasis. Changes in the ECM are critical for normal tissue repair, whereas dysregulation contributes to aberrant tissue remodeling. Pulmonary arterial hypertension is a severe disorder of the pulmonary vasculature characterized by pathologic remodeling of the pulmonary vasculature and right ventricle, increased production and deposition of structural and nonstructural proteins, and altered expression of ECM growth factors and proteases. Furthermore, ECM remodeling plays a significant role in disease progression, as several dynamic changes in its composition, quantity, and organization are documented in both humans and animal models of disease. These ECM changes impact vascular cell biology and affect proliferation of resident cells. Furthermore, ECM components determine the tissue architecture of the pulmonary and myocardial vasculature as well as the myocardium itself and provide mechanical stability crucial for tissue homeostasis. However, little is known about the basement membrane (BM), a specialized, self-assembled conglomerate of ECM proteins, during remodeling. In the vasculature, the BM is in close physical association with the vascular endothelium and smooth muscle cells. While in the myocardium, each cardiomyocyte is enclosed by a BM that serves as the interface between cardiomyocytes and the surrounding interstitial matrix. In this review, we provide a brief overview on the current state of knowledge of the BM and its ECM composition and their impact on pulmonary vascular remodeling and right ventricle dysfunction and failure in pulmonary arterial hypertension.

An overview of human pericardial space and pericardial fluid

The pericardium is a double-layered fibro-serous sac that envelops the majority of the surface of the heart as well as the great vessels. Pericardial fluid is also contained within the pericardial space. Together, the pericardium and pericardial fluid contribute to a homeostatic environment that facilitates normal cardiac function. Different diseases and procedural interventions may disrupt this homeostatic space causing an imbalance in the composition of immune mediators or by mechanical stress. Inflammatory cells, cytokines, and chemokines are present in the pericardial space. How these specific mediators contribute to different diseases is the subject of debate and research. With the advent of highly specialized assays that can identify and quantify various mediators we can potentially establish specific and sensitive biomarkers that can be used to differentiate pathologies, and aid clinicians in improving clinical outcomes for patients.

Recruitment and maturation of the coronary collateral circulation: Current understanding and perspectives in arteriogenesis

The coronary collateral circulation is a rich anastomotic network of primitive vessels which have the ability to augment in size and function through the process of arteriogenesis. In this review, we evaluate the current understandings of the molecular and cellular mechanisms by which this process occurs, specifically focussing on elevated fluid shear stress (FSS), inflammation, the redox state and gene expression along with the integrative, parallel and simultaneous process by which this occurs. The initiating step of arteriogenesis occurs following occlusion of an epicardial coronary artery, with an increase in FSS detected by mechanoreceptors within the endothelium. This must occur within a 'redox window' where an equilibrium of oxidative and reductive factors are present. These factors initially result in an inflammatory milieu, mediated by neutrophils as well as lymphocytes, with resultant activation of a number of downstream molecular pathways resulting in increased expression of proteins involved in monocyte attraction and adherence; namely vascular cell adhesion molecule 1 (VCAM-1), monocyte chemoattractant protein 1 (MCP-1) and transforming growth factor beta (TGF-β). Once monocytes and other inflammatory cells adhere to the endothelium they enter the extracellular matrix and differentiate into macrophages in an effort to create a favourable environment for vessel growth and development. Activated macrophages secrete inflammatory cytokines such as tumour necrosis factor-α (TNF-α), growth factors such as fibroblast growth factor-2 (FGF-2) and matrix metalloproteinases. Finally, vascular smooth muscle cells proliferate and switch to a contractile phenotype, resulting in an increased diameter and functionality of the collateral vessel, thereby allowing improved perfusion of the distal myocardium subtended by the occluded vessel. This simultaneously reduces FSS within the collateral vessel, inhibiting further vessel growth.

Endostatin as a novel prognostic biomarker in acute ischemic stroke

BACKGROUND AND AIMS

Endostatin is implicated in the atherosclerosis process and serves as a promising cardiovascular biomarker, while its clinical significance in ischemic stroke patients remains unclear. We aimed to examine the association between endostatin and mortality and disability after ischemic stroke.

METHODS

A total of 3463 acute ischemic stroke patients with measured plasma endostatin from the China Antihypertensive Trial in Acute Ischemic Stroke were included in this study. The primary outcome was death or severe disability (modified Rankin scale score of 4-6), and secondary outcomes included death and vascular events.

RESULTS

After 3-month follow-up, 402 (11.61%) participants experienced severe disability or died. Compared with the lowest quartile of endostatin, odds ratios or hazard ratios (95% confidence intervals) for the highest quartile were 1.47 (1.04-2.09) for the primary outcome, and 2.36 (1.23-4.54) for death after adjustment for multiple covariates, including age, sex, admission NIH Stroke Scale score and systolic blood pressure. Each 1-SD higher log-transformed endostatin was associated with a 20% (6%-36%) increased risk for primary outcome. Adding plasma endostatin to the basic model constructed with conventional factors significantly improved risk stratification of primary outcome, as observed by the category-free net reclassification index of 20.5% (95% CI 10.1%-30.8%; p < 0.001) and integrated discrimination improvement of 0.3% (95% CI 0.01%-0.6%; p = 0.04).

CONCLUSIONS

Increased baseline plasma endostatin levels in acute ischemic stroke were associated with increased risk of mortality and severe disability at 3 months. Plasma endostatin may serve as an important prognostic marker for risk stratification in patients with ischemic stroke.

Technologies for intrapericardial delivery of therapeutics and cells

The pericardium, which surrounds the heart, provides a unique enclosed volume and a site for the delivery of agents to the heart and coronary arteries. While strategies for targeting the delivery of therapeutics to the heart are lacking, various technologies and nanodelivery approaches are emerging as promising methods for site specific delivery to increase therapeutic myocardial retention, efficacy, and bioactivity, while decreasing undesired systemic effects. Here, we provide a literature review of various approaches for intrapericardial delivery of agents. Emphasis is given to sustained delivery approaches (pumps and catheters) and localized release (patches, drug eluting stents, and support devices and meshes). Further, minimally invasive access techniques, pericardial access devices, pericardial washout and fluid analysis, as well as therapeutic and cell delivery vehicles are presented. Finally, several promising new therapeutic targets to treat heart diseases are highlighted.

The Extracellular Matrix in Ischemic and Nonischemic Heart Failure

The ECM (extracellular matrix) network plays a crucial role in cardiac homeostasis, not only by providing structural support, but also by facilitating force transmission, and by transducing key signals to cardiomyocytes, vascular cells, and interstitial cells. Changes in the profile and biochemistry of the ECM may be critically implicated in the pathogenesis of both heart failure with reduced ejection fraction and heart failure with preserved ejection fraction. The patterns of molecular and biochemical ECM alterations in failing hearts are dependent on the type of underlying injury. Pressure overload triggers early activation of a matrix-synthetic program in cardiac fibroblasts, inducing myofibroblast conversion, and stimulating synthesis of both structural and matricellular ECM proteins. Expansion of the cardiac ECM may increase myocardial stiffness promoting diastolic dysfunction. Cardiomyocytes, vascular cells and immune cells, activated through mechanosensitive pathways or neurohumoral mediators may play a critical role in fibroblast activation through secretion of cytokines and growth factors. Sustained pressure overload leads to dilative remodeling and systolic dysfunction that may be mediated by changes in the interstitial protease/antiprotease balance. On the other hand, ischemic injury causes dynamic changes in the cardiac ECM that contribute to regulation of inflammation and repair and may mediate adverse cardiac remodeling. In other pathophysiologic conditions, such as volume overload, diabetes mellitus, and obesity, the cell biological effectors mediating ECM remodeling are poorly understood and the molecular links between the primary insult and the changes in the matrix environment are unknown. This review article discusses the role of ECM macromolecules in heart failure, focusing on both structural ECM proteins (such as fibrillar and nonfibrillar collagens), and specialized injury-associated matrix macromolecules (such as fibronectin and matricellular proteins). Understanding the role of the ECM in heart failure may identify therapeutic targets to reduce geometric remodeling, to attenuate cardiomyocyte dysfunction, and even to promote myocardial regeneration.

Circulating endostatin as a risk factor for cardiovascular events in patients with stable coronary heart disease: A CLARICOR trial sub-study

BACKGROUND AND AIMS

Raised levels of serum endostatin, a biologically active fragment of collagen XVIII, have been observed in patients with ischemic heart disease but association with incident cardiovascular events in patients with stable coronary heart disease is uncertain.

METHODS

The CLARICOR-trial is a randomized, placebo-controlled trial of stable coronary heart disease patients evaluating 14-day treatment with clarithromycin. The primary outcome was a composite of acute myocardial infarction, unstable angina pectoris, cerebrovascular disease or all-cause mortality. In the present sub-study using 10-year follow-up data, we investigated associations between serum endostatin at entry (randomization) and the composite outcome and its components during follow-up. The placebo group was used as discovery sample (1204 events, n = 1998) and the clarithromycin-treated group as replication sample (1220 events, n = 1979).

RESULTS

In Cox regression models adjusting for cardiovascular risk factors, glomerular filtration rate, and current pharmacological treatment, higher serum endostatin was associated with an increased risk of the composite outcome in the discovery sample (hazard ratio per standard deviation increase 1.11, 95% CI 1.03-1.19, p = 0.004), but slightly weaker and not statistically significant in the replication sample (hazard ratio 1.06, 95% CI 1.00-1.14, p = 0.06). In contrast, strong and consistent associations were found between endostatin and cardiovascular and all-cause mortality in all multivariable models and sub-samples. Addition of endostatin to a model with established cardiovascular risk factors provided no substantial improvement of risk prediction (<1%).

CONCLUSIONS

Raised levels of serum endostatin might be associated with cardiovascular events in patients with stable coronary heart disease. The clinical utility of endostatin measurements remains to be established.

New Insights into the Role of Basement Membrane-Derived Matricryptins in the Heart

The extracellular matrix (ECM), which contributes to structural homeostasis as well as to the regulation of cellular function, is enzymatically cleaved by proteases, such as matrix metalloproteinases and cathepsins, in the normal and diseased heart. During the past two decades, matricryptins have been defined as fragments of ECM with a biologically active cryptic site, namely the 'matricryptic site,' and their biological activities have been initially identified and clarified, including anti-angiogenic and anti-tumor effects. Thus, matricryptins are expected to be novel anti-tumor drugs, and thus widely investigated. Although there are a smaller number of studies on the expression and function of matricryptins in fields other than cancer research, some matricryptins have been recently clarified to have biological functions beyond an anti-angiogenic effect in heart. This review particularly focuses on the expression and function of basement membrane-derived matricryptins, including arresten, canstatin, tumstatin, endostatin and endorepellin, during cardiac diseases leading to heart failure such as cardiac hypertrophy and myocardial infarction.

Mdivi-1 induced acute changes in the angiogenic profile after ischemia-reperfusion injury in female mice

The aim of this study is to determine the effects of mitochondrial division inhibitor 1 (Mdivi‐1), the mitochondrial fission inhibitor, on the angiogenic profiles after the ischemia reperfusion injury (IR injury) in female mice. Female mice were treated with Mdivi‐1 inhibitor, 2 days prior, on the day of IR injury and 2 days after IR injury, for a period of 5 days. Both control and treatment groups underwent 30 min of ischemia and 72 h of reperfusion. On the day 3, mice were sacrificed and the ischemic and nonischemic portions of heart tissue were collected. Relative levels of 53 angiogenesis‐related proteins were quantified simultaneously using Angiogenic arrays. Heart function was evaluated before and after 72 h of IR injury. Mdivi‐1 treatment ameliorated IR induced functional deterioration with positive angiogenic profile. The seminal changes include suppression of Matrix metalloproteinase (MMP3), tissue inhibitor of metalloproteases (TIMP1) and chemokine (C‐X‐C motif) ligand 10 (CXCL10) levels and prevention of connexin 43 (Cx43) loss and downregulation in the antioxidant enzyme levels. These changes are correlated with enhanced endothelial progenitor cell marker (cluster of differentiation (CD31), endothelial‐specific receptor tyrosine kinase (Tek), fMS‐like tyrosine kinase 4 (Flt4) and kinase insert domain protein receptor (Kdr)) presence. Our study is the first to report the role of mitochondrial dynamics in regulation of myocardial IR‐induced angiogenic responses. Inhibition of excessive mitochondrial fission after IR injury ameliorated heart dysfunction and conferred positive angiogenic response. In addition, there were improvements in the preservation of Cx43 levels and oxidative stress handling along with suppression of apoptosis activation. The findings will aid in shaping the rational drug development process for the prevention of ischemic heart disease, especially in females.

Endostatin: a promising biomarker in the cardiovascular continuum?

The current review article aims to provide an up-to-date summary of previous studies in humans that have reported the association between circulating endostatin levels and different cardiovascular phenotypes. We also aim to provide suggestions for future directions of future research evaluating endostatin as a clinically relevant cardiovascular biomarker. With a few exceptions, higher circulating levels of endostatin seem to reflect vascular and myocardial damage, and a worsened prognosis for cardiovascular events or mortality in individuals with hypertension, diabetes, kidney disease, cardiovascular disease, as well as in the general population. Circulating endostatin seems to be a promising biomarker for cardiovascular pathology, but there is not enough evidence to date to support the use of endostatin measurements in clinical practice.

Endostatin a Potential Biomarker for Heart Failure with Preserved Ejection Fraction

Background

Endostatin is a circulating endogenous angiogenesis inhibitor preventing neovascularization. Previous studies demonstrated the prognostic value of Endostatin among patients with heart failure with reduced ejection fraction (HFrEF). However, the role of Endostatin among patients with heart failure with preserved ejection fraction (HFpEF) remains unclear.

Objective

This study aimed to investigate the association between serum Endostatin levels, natriuretic peptide levels and the severity of left ventricular diastolic dysfunction and the diagnosis of HFpEF.

Methods

Endostatin serum concentrations were measured in 301 patients comprising 77 HFpEF patients, 169 patients with asymptomatic left ventricular diastolic dysfunction (ALVDD), and 55 controls with normal cardiac function.

Results

Endostatin serum levels were significantly elevated in patients with HFpEF (median/interquartile range 179.0 [159-220]) and ALVDD (163.8 [145.4-191.3]) compared to controls (149.1 [130.6-176.9]), p < 0.001 and p = 0.004, respectively) and significant correlated with N-terminal pro B-type natriuretic peptide (NT-proBNP).

Conclusions

This hypothesis-generating pilot study gives first evidence that Endostatin correlates with the severity of diastolic dysfunction and may become a novel biomarker for HFpEF. We hypothesize a rise in Endostatin levels may reflect inhibition of adaptive angiogenesis and adverse cardiac remodeling.

Spotlight on endothelial progenitor cell inhibitors: short review

Endothelial progenitor cells (EPCs) are bone-marrow-derived cells that enter the systemic circulation to replace defective or injured mature endothelial cells. EPCs also contribute to neovascularization and limit the progression of atherosclero sis. Patients with reduced EPC levels or dysfunctional EPCs are at increased risk for coronary artery disease. Drug-mediated improvement of the mobilization, differenti ation, function and homing of EPCs to sites of ischemia or injured endothelium may therefore be a promising novel therapeutic approach for various cardiovascular dis eases. On the other hand, endogenous inhibitors of EPCs could also be valuable drug targets. The identification of EPC inhibitors and the development of novel drugs that can efficiently regulate production or elimination of these molecules may also be a promising approach for the future treatment of atherosclerosis. In the present review we summarize potential endogenous and exogenous inhibitors of EPCs, such as oxidized low-density lipoproteins, angiotensin II, glucose, cigarette smoke and others. Whenever possible, we also describe the underlying molecular events. Drug- induced mobilization and improvement of EPC function, as well as reduction of EPC inhibitors, is likely to enhance endothelial function and reduce atherosclerotic processes.

Endostatin in chronic kidney disease: Associations with inflammation, vascular abnormalities, cardiovascular events and survival

BACKGROUND AND AIMS

Endostatin, generated from collagen XVIII, and endorepellin, possess dual activity as modifiers of both angiogenesis and endothelial cell autophagy. Plasma endostatin levels are elevated in a large number of diseases, and may reflect endothelial cell dysfunction. Few data on endostatins are available for patients with chronic kidney disease (CKD). We tested whether serum endostatin values are predictive for all-cause mortality and cardiovascular events (CVEs) in a CKD population.

MATERIALS AND METHOD

A total of 519 CKD pre-dialysis patients were included. Baseline plasma endostatin levels were measured in all patients. All included patients were followed-up (time-to-event analysis) until occurrence of death, fatal or nonfatal CVEs. Fatal and nonfatal CVE including death, stroke, and myocardial infarction were recorded prospectively

RESULTS

The mean age of the patients was 52.2±12.3years. There were 241 (46.4%) males, 111 (21.4%) had diabetes, 229 (44.1%) were smokers and 103 (19.8%) had a previous CVE. After a median follow-up of 46months, 46 patients died and 172 had a new CVE. In the univariable Cox survival analysis, higher endostatin levels were associated with a higher risk for both outcomes. However, after adjusting for traditional (age, gender, smoking status, diabetes, systolic blood pressure, HDL and total cholesterol) and renal-specific (eGFR, proteinuria and hsCRP) risk factors, endostatin levels remained associated only with the CVE outcome (HR=1.88, 95% CI 1.37-2.41 for a 1 SD increase in log endostatin values).

CONCLUSION

Endostatin levels are independently associated with incident CVE in CKD patients, but show limited prediction abilities for all-cause mortality and CVE above traditional and renal-specific risk factors.

Relationship between thrombospondin-1, endostatin, angiopoietin-2, and coronary collateral development in patients with chronic total occlusion

This study is aimed to investigate whether serum angiostatic factors (thrombospondin-1 [TSP-1] and endostatin) or angiogenic factors (angiopoietin-2 [Ang-2]) are related to coronary collateral vessel development in patients with chronic total occlusion (CTO).A total of 149 patients were enrolled in the study, and 39 patients with coronary artery disease but without significant stenosis were included in control group. In 110 patients with CTO lesion, 79 with Rentrop grades 2 to 3 collaterals were grouped as good collateral, while 31 with Rentrop grades 0 to 1 collaterals were grouped as poor collateral. Serum TSP-1, endostatin, and Ang-2 levels were studied.Serum endostatin level was significantly higher in poor collateral group compared with control group and good collateral group, respectively (96.2 ± 30.4 vs 77.8 ± 16.5 ng/mL, P = 0.007; 96.2 ± 30.4 vs 81.2 ± 30.4 ng/mL, P = 0.018). In multivariate analysis, decreased serum endostatin level was independently related to good coronary collateral development. Serum TSP-1 level was lower in patients with CTO compared with control group. However, no difference in TSP-1 level was detected between poor and good collateral group. The serum Ang-2 level did not show a significant difference among 3 groups.Circulatory endostatin may be a useful biomarker for coronary collateral development and potential target for therapeutic angiogenesis in patients with CTO.

The association between endostatin and kidney disease and mortality in patients with type 2 diabetes

AIM

Circulating endostatin, a biologically active derivate of collagen XVIII, is considered to be a marker of kidney disease and a risk factor for its related mortality. However, less is known of the role of endostatin in diabetes and the development of diabetic nephropathy. For this reason, our study investigated the associations between circulating endostatin and the prevalence and progression of kidney disease, and its mortality risk in patients with type 2 diabetes (T2D).

METHODS

This was a cohort study of 607 patients with T2D (mean age: 61 years, 44% women). Estimated glomerular filtration rate (eGFR), calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation, was used to assess the patients' kidney function decline and mortality.

RESULTS

Of the total study cohort, 20 patients declined by ≥20% in eGFR over 4 years, and 44 died during the follow-up (mean duration: 6.7 years). At baseline, participants with diabetic nephropathy (defined as eGFR<60mL/min/1.73m²) and/or microalbuminuria [defined as a urinary albumin-to-creatinine ratio (ACR)>3g/mol] had higher median levels of endostatin than those without nephropathy (62.7μg/L vs 57.4μg/L, respectively; P=0.031). In longitudinal analyses adjusted for age, gender, baseline eGFR and ACR, higher endostatin levels were associated with a higher risk of decline (≥20% in eGFR, OR per 1 SD increase: 1.73, 95% CI: 1.13-2.65) and a higher risk of mortality (HR per 1 SD increase: 1.57, 95% CI: 1.19-2.07).

CONCLUSION

In patients with T2D, circulating endostatin levels can predict the progression of kidney disease and mortality independently of established kidney disease markers. The clinical usefulness of endostatin as a risk marker in such patients merits further studies.

Physical inactivity increases endostatin and osteopontin in patients with coronary artery disease

The balance between the angiostatic factor endostatin (ES) and angiogenic factor osteopontin (OPN) is essential in physiological and pathological angiogenesis. Several circumstances might influence this equilibrium and are of distinct interest when investigating mechanisms in coronary artery disease (CAD). The present explorative cross-sectional study was to investigate the influence of physical inactivity on ES and OPN levels in 181 male and 71 female patients with angiographycally verified CAD. Anamnestic and laboratory data were collected; ES was measured in serum and OPN in plasma by ELISA. Univariate analysis of variance was used to test for the influence of physical activity on ES and OPN levels and age, BMI, sex and diabetes status were included as covariates. ES and OPN intercorrelated significantly (r = 0.42; p < 0.001). ES and OPN decreased significantly in response to increasing activity level of patients suffering CAD (F = 5.5; p < 0.001 and F = 3.6; p < 0.01 resp.). This study is the first to show a linear decrease in ES and OPN levels in CAD patients depending on the degree of physical activity undergone. Lower levels of ES and OPN in physically active patients might be a sign of increased angiogenesis and decreased inflammation and calcifying activity and therefore contribute to the understanding of the damaging effect of physical inactivity in cardiovascular disease.

Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine

Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.

Association of circulating angiogenesis inhibitors and asymmetric dimethyl arginine with coronary plaque burden

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for the development and severity of coronary artery disease (CHD) and endothelial dysfunction. There is an increase in the circulating angiogenesis inhibitors endostatin (END), thrombospondin-2 (TSP), angiopoietin-2 (ANG) and the nitric oxide (NO) inhibitor asymmetric dimethyl arginine (ADMA) in CKD patients. The aim of this study was to evaluate associations of the serum level of these factors and of the related angiogenesis inhibitor, endoglin (ENG), with burden of coronary atherosclerosis.

METHODS

One hundred twenty-two patients undergoing coronary angiography were recruited from the cardiac catheterization lab at a single center. The total burden of coronary plaque (mm(2)) and the presence of coronary collaterals were quantified using quantitative coronary angiography (QCA). Serum levels of angiogenesis inhibitors were measured by ELISA (ENG, END, and ANG), Luminex assay (TSP), or HLPC (ADMA), respectively. Associations with plaque burden and coronary collateral supply were analyzed in multi-variable linear and logistic regression models.

RESULTS

There was no significant association found between levels of circulating ADMA, ENG, END, ANG, or TSP and coronary plaque burden or collateral formation.

CONCLUSIONS

Our findings suggest that associations of circulating END, ENG, TSP, and ANG with cardiovascular mortality are unlikely to be mediated via direct effects on coronary plaque formation or by inhibition of collateral formation. Whether associations of these factors with mortality are mediated via local concentrations, myocardial tissue, or intra-plaque expression of these factors or by an effect on plaque vulnerability merits additional investigation.

Serum endostatin is a genetically determined predictor of survival in pulmonary arterial hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) is a medically incurable disease resulting in death from right ventricular (RV) failure. Both pulmonary vascular and RV remodeling are linked to dynamic changes in the microvasculature. Therefore, we hypothesized that circulating angiostatic factors could be linked to outcomes and represent novel biomarkers of disease severity in PAH.

OBJECTIVES

We sought to determine the relationship of a potent angiostatic factor, endostatin (ES), with disease severity and mortality in PAH. Furthermore, we assessed genetic predictors of ES expression and/or function and their association with outcomes in PAH.

METHODS

We measured levels of serum ES in two independent cohorts of patients with PAH. Contemporaneous clinical data included New York Heart Association functional class, 6-minute-walk distance, invasive hemodynamics, and laboratory chemistries.

MEASUREMENTS AND MAIN RESULTS

Serum ES correlated with poor functional status, decreased exercise tolerance, and invasive hemodynamics variables. Furthermore, serum ES was a strong predictor of mortality. A loss-of-function, missense variant in the gene encoding ES, Col18a1, was linked to lower circulating protein and was independently associated with reduced mortality.

CONCLUSIONS

Our data link increased expression of ES to disease severity in PAH and demonstrate a significant relationship with adverse outcomes. Circulating ES levels can be genetically influenced, implicating ES as a genetically determined modifier of disease severity impacting on survival. These observations support serum ES as a potential biomarker in PAH with the capacity to predict poor outcomes. More importantly, this study implicates Col18a1/ES as a potential new therapeutic target in PAH.

Racial differences in the burden of coronary artery calcium and carotid intima media thickness between Blacks and Whites

Background

Identification of racial differences in the burden and correlates of carotid intima media thickness (CIMT) and coronary artery calcium (CAC) may provide the basis for the development of race-specific cardiovascular disease (CVD) risk prediction algorithms.

Methods

In the Heart Strategies Concentrating on Risk Evaluation (Heart SCORE) study, CIMT was measured by carotid ultrasonography in 792 individuals (35 % Black). CIMT >1 mm was considered significant. CAC was quantified by electron beam computed tomography in 776 individuals (46 % Black). CAC was considered significant if the Agatston score was >100. Cross-sectional associations between race, CIMT and CAC were assessed using logistic regression models.

Results

Blacks had greater CIMT (mean difference 0.033 mm, 95 % CI 0.005–0.06 mm; p = 0.02) and 1.5-fold (95 % CI 1.0–2.3) higher odds of having significant CIMT than Whites. Blacks had less CAC than Whites (mean Agatston score difference 66, [11–122]; p = 0.02) and 50 % lower odds of a significant CAC score compared with Whites (0.5 [0.3–0.7]). These associations were virtually unchanged after adjustment for CVD risk factors. Of the novel CVD risk markers assessed, small-dense low-density lipoprotein was independently associated with increased odds of significant CIMT, with the association being similar among Blacks and Whites (odds ratio [95 % CI]: 1.7 [1.2–2.5] and 1.4 [1.0–1.8] per 1-SD higher level, respectively). Interleukin-6 was significantly associated with CAC among Blacks (1.4 [1.0–2.0]).

Conclusion

Black race is independently associated with greater CIMT but less CAC than White race. CVD risk stratification strategies that incorporate these measures of subclinical atherosclerosis should consider race-specific algorithms.

Electronic supplementary material

The online version of this article (doi:10.1007/s12471-014-0610-4) contains supplementary material, which is available to authorized users.

Association of endostatin with mortality in patients with chronic heart failure

BACKGROUND

Experimental data imply that in decompensated heart failure (HF), the anti-angiogenic factor endostatin is increased. This study aimed to investigate whether the angiogenesis inhibitor endostatin is related to the risk of all-cause mortality in a prospective cohort study of chronic HF patients.

METHODS

In this prospective observational cohort study, endostatin serum concentrations were determined in patients with chronic HF. Mortality data were recorded during a median follow-up of 31 months.

RESULTS

One fifty one patients were included. The overall mortality rate was 20%. Baseline endostatin concentrations > 245 ng/mL were associated with higher risk of all-cause mortality [HR 8·7 (95% CI 2·5-30·0); P = 0·001] in the multivariate analysis as compared to endostatin concentrations ≤ 245 ng/mL. When both endostatin and NT-proBNP were above the calculated cut-off of 245 ng/mL and 2386 pg/mL, respectively, the prognostic utility of both biomarkers increased [HR 40·8 (95% CI 4·7-354·6); P = 0·001] compared with values lower than the cut-offs.

CONCLUSIONS

Serum endostatin concentrations are independently associated with all-cause mortality. Furthermore, combination of endostatin and NT-proBNP discriminates patients at high risk.

Association between circulating endostatin, hypertension duration, and hypertensive target-organ damage

Our aim is to study associations between circulating endostatin, hypertension duration, and hypertensive target-organ damage. Long-term hypertension induces cardiovascular and renal remodeling. Circulating endostatin, a biologically active derivate of collagen XVIII, has been suggested to be a relevant marker for extracellular matrix turnover and remodeling in various diseases. However, the role of endostatin in hypertension and hypertensive target-organ damage is unclear. Serum endostatin was measured in 2 independent community-based cohorts: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS; women 51%; n = 812; mean age, 75 years) and the Uppsala Longitudinal Study of Adult Men (ULSAM; n=785; mean age, 77.6 years). Retrospective data on blood pressure measurements and antihypertensive medication (PIVUS >5 years, ULSAM >27 years), and cross-sectional data on echocardiographic left ventricular mass, endothelial function (endothelium-dependent vasodilation assessed by the invasive forearm model), and urinary albumin/creatinine ratio were available. In PIVUS, participants with ≥ 5 years of history of hypertension portrayed 0.42 SD (95% confidence interval, 0.23-0.61; P<0.001) higher serum endostatin, compared with that of normotensives. This association was replicated in ULSAM, in which participants with 27 years hypertension duration had the highest endostatin (0.57 SD higher; 95% confidence interval, 0.35-0.80; P<0.001). In addition, higher endostatin was associated with higher left ventricular mass, worsened endothelial function, and higher urinary albumin/creatinine ratio (P<0.03 for all) in participants with prevalent hypertension. Circulating endostatin is associated with the duration of hypertension, and vascular, myocardial, and renal indices of hypertensive target-organ damage. Further studies are warranted to assess the prognostic role of endostatin in individuals with hypertension.

Serum endostatin and risk of mortality in the elderly: findings from 2 community-based cohorts

OBJECTIVE

Experimental data imply that endostatin, a proteolytically cleaved fragment of collagen XVIII, could be involved in the development of cardiovascular disease and cancer. Prospective data concerning the relation between circulating endostatin and mortality are lacking. Accordingly, we aimed to study associations between circulating endostatin and mortality risk.

APPROACH AND RESULTS

Serum endostatin was analyzed in 2 community-based cohorts: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS; women 50%, n=931; mean age, 70 years; median follow-up, 7.9 years) and the Uppsala Longitudinal Study of Adult Men (ULSAM; n=748; mean age, 77 years; median follow-up, 9.7 years). During follow-up, 90 participants died in PIVUS (1.28/100 person-years at risk), and 417 participants died in ULSAM (6.7/100 person-years at risk). In multivariable Cox regression models adjusted for age and established cardiovascular risk factors, 1 SD higher ln(serum endostatin level) was associated with a hazard ratio of mortality of 1.39 and 95% confidence interval, 1.26 to 1.53, on average in both cohorts. In the ULSAM cohort, serum endostatin was also associated with cardiovascular mortality (177 deaths; hazard ratio per SD of ln[endostatin] 1.45, 95% confidence interval [1.25-1.71]) and cancer mortality (115 deaths; hazard ratio per SD of ln[endostatin] 1.35, 95% confidence interval [1.10-1.66]).

CONCLUSIONS

High serum endostatin was associated with increased mortality risk in 2 independent community-based cohorts of the elderly. Our observational data support the importance of extracellular matrix remodeling in the underlying pathophysiology of cardiovascular disease and cancer.

Changes of serum angiogenic factors concentrations in patients with diabetes and unstable angina pectoris

Backgroud

Diabetic microvascular changes are considered to be influenced by angiogenic factors. As a compensatory mechanism, the expression of some angiogenic factors are elevated in ischemic myocardium. The aim of this study was to investigate the changes of serum angiogenic factors, and the association among these angiogenic factors, the severity of coronary artery stenosis and collateral vessels form in patients with diabetes and unstable angina pectoris (UAP).

Methods

42 patients with diabetes (diabetes group), 57 patients with UAP (UAP group), and 36 age-matched healthy people (control group) were selected. Serum concentrations of angiogenic factors were measured using cytokine array technology. The severity of coronary artery stenosis was scored using the angiographic Gensini score. Coronary collateral vessels were scored according to Rentrop's classification.

Results

No significant differences in the serum concentrations of vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), angiogenin, angiostatin, basic fibroblast growth factor (bFGF) and platelet-derived growth factor-BB (PDGF-BB) were detected between control group and diabetes group. But in patients with diabetes complicated with UAP and in patients with UAP without diabetes, serum concentrations of VEGF and Ang-2 were elevated (p < 0.01, p < 0.01). Only serum Ang-2 concentrations were significantly correlated with Gensini score (r=0.585, p < 0.001), left ventricular end diastolic diameter (r=0.501, p < 0.001), left ventricular end systolic diameter (r=0.563, p < 0.001) and left ventricular ejection fraction (r=−0.523, p < 0.001).

Conclusion

Serum concentrations of VEGF and Ang-2 were increased, and diabetes didn’t affect this increases in patients with UAP. Serum Ang-2 concentrations were correlated with the severity of coronary artery stenosis.

Mechanistic, technical, and clinical perspectives in therapeutic stimulation of coronary collateral development by angiogenic growth factors

Stimulation of collateral vessel development in the heart by angiogenic growth factor therapy has been tested in animals and humans for almost two decades. Discordance between the outcome of preclinical studies and clinical trials pointed to the difficulties of translation from animal models to patients. Lessons learned in this process identified specific mechanistic, technical, and clinical hurdles, which need to be overcome. This review summarizes current understanding of the mechanisms leading to the establishment of a functional coronary collateral network and the biological processes growth factor therapies should stimulate even under conditions of impaired natural adaptive vascular response. Vector delivery methods are recommended to maximize angiogenic gene therapy efficiency and reduce side effects. Optimization of clinical trial design should include the choice of clinical end points which provide mechanistic proof-of-concept and also reflect clinical benefits (e.g., surrogates to assess increased collateral flow reserve, such as myocardial perfusion imaging). Guidelines are proposed to select patients who may respond to the therapy with high(er) probability. Both short and longer term strategies are outlined which may help to make therapeutic angiogenesis (TA) work in the future.

Endogenous angiogenesis inhibitors prevent adaptive capillary growth in left ventricular pressure overload hypertrophy

BACKGROUND

In left ventricular (LV) pressure-overload hypertrophy, lack of adaptive capillary growth contributes to progression to failure. Remodeling of the hypertrophied myocardium requires proteolysis of the extracellular matrix (ECM) carried out by matrix metalloproteinases (MMPs). MMPs, specifically MMP-9, are known to cleave ECM components to generate angiogenesis inhibitors (angiostatin, endostatin, tumstatin). We hypothesize that MMP-9 releases antiangiogenic factors during compensated and decompensated hypertrophy, which results in lack of adaptive capillary growth.

METHODS

Newborn rabbits underwent aortic banding. Myocardial tissue from age-matched and banded animals at compensated (4 weeks) and decompensated hypertrophy (7 weeks), as identified by serial echocardiography, was analyzed by immunoblotting for angiostatin, endostatin, and tumstatin. MMP-9 activity was determined by zymography. A cell-permeable, potent, selective MMP-9 inhibitor was administered intrapericardially to animals with hypertrophied hearts and tissue was analyzed.

RESULTS

MMP-9 is activated in hypertrophied myocardium versus in control hearts (22 ± 2 versus 16 ± 1; p = 0.04), which results in significantly increased levels of angiostatin (115 ± 10 versus 86 ± 7; p = 0.02), endostatin (33 ± 1 versus 28 ± 1; p = 0.006), and tumstatin (35 ± 6 versus 17 ± 4; p = 0.04). Zymography confirms inhibition of MMP-9 (hypertrophy + MMP-9 inhibitor, 14 ± 0.6 versus hypertrophy + vehicle, 17 ± 1; p = 0.01) and angiostatin, endostatin, and tumstatin are down-regulated, accompanied by up-regulation of capillary density (hypertrophy + MMP-9 inhibitor, 2.99 ± 0.07 versus hypertrophy + vehicle, 2.7 ± 0.05; p = 0.002).

CONCLUSIONS

Up-regulation of angiogenesis inhibitors prevents adaptive capillary growth in pressure-overload hypertrophied myocardium. Therapeutic interventions aimed at inhibition of angiogenesis inhibitors are useful in maintaining capillary density and thereby preventing heart failure.

Plasma chemokine levels are associated with the presence and extent of angiographic coronary collaterals in chronic ischemic heart disease

BACKGROUND

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.

METHODOLOGY/PRINCIPAL FINDINGS

We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).

CONCLUSIONS/SIGNIFICANCE

Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment.

Coronary collateral growth and its therapeutic application to coronary artery disease

There is a tremendous body of data concerning the coronary collateral circulation in both experimental animals and humans. The functional importance of a well-developed coronary collateral circulation has now been documented. The paradigm regarding the principal stimulus for coronary collateral growth has shifted from myocardial ischemia to increased shear stress at the site of pre-existing collateral arterioles. Numerous experimental and clinical studies have contributed to elucidation of the mechanisms of coronary collateral growth. Stimulation of coronary collateral growth is an alternative therapeutic approach to patients with intractable angina pectoris who are not indicated for percutaneous coronary intervention and/or coronary artery bypass grafting. Pharmacological and mechanical modulations accelerating coronary collateral growth have been challenged. Because it is conceivable that a well-developed coronary collateral circulation attenuates myocardial ischemia upon exercise, further research addressing coronary collateral growth is needed in both experimental models of myocardial ischemia and human coronary artery disease.

Local cytokine concentrations and oxygen pressure are related to maturation of the collateral circulation in humans

OBJECTIVES

Our aim was to determine cytokine and oxygen gradients over the collateral circulation in humans.

BACKGROUND

The molecular background of the maturation of the collateral circulation in response to coronary narrowing is poorly understood in humans, partly because of difficulties in obtaining local samples from the human collateral circulation.

METHODS

Coronary collateral blood was sampled in 60 patients with nontotal (n = 25) or total coronary occlusions (n = 35) using a special wide-lumen catheter. Coronary collateral flow index (CFI) was assessed by intracoronary pressure measurements. Oxygenation and lactate content was measured as well as 30 cytokines potentially involved in collateral artery growth, using a custom-made multiplex assay.

RESULTS

No rise in lactate or change in pH was found in collateral blood. Oxygen gradient between coronary and collateral arterial blood correlated inversely with CFI (r = -0.61, p < 0.001). Locally increased plasma levels were found for basic fibroblast growth factor, eotaxin, macrophage migration inflammatory factor, monocyte chemoattractant protein-1, and transforming growth factor-beta, while stem cell factor and stem cell growth factor-beta were significantly decreased. The highest cytokine gradients were found in patients with the least developed collateral circulation. The majority of cytokines correlated more strongly with the pO(2) gradient across the collateral bed than with CFI.

CONCLUSIONS

Intravascular ischemia during brief balloon coronary occlusion is absent in human coronary collateral arteries. The oxygen gradient found over the collateral circulation is increased in patients with a less matured collateral circulation and relates to local levels of several known pro-arteriogenic cytokines. In case of a more developed collateral circulation, relatively low levels of cytokines are present, suggesting that growth factor therapy might be beneficial at this stage.

Endostatin and angiostatin are increased in diabetic patients with coronary artery disease and associated with impaired coronary collateral formation

Coronary artery disease (CAD) is the leading cause of mortality in diabetic patients. Because of the diffuse nature of their disease, diabetic patients may be at risk for incomplete revascularization, highlighting a potential role for proangiogenic therapy in this group. This study investigates molecular mechanisms of angiogenesis in diabetic patients. Myocardial tissue was harvested from patients undergoing coronary artery bypass grafting [nondiabetic (ND) 11, type 2 diabetic (DM) 10]. Expression of angiostatin, endostatin, their precursors (plasminogen and collagen XVIII, respectively), enzymes leading to their production [matrix metalloprotease (MMP)-2 and -9, cathepsin L], and an inhibitor of MMPs (tissue inhibitor of metalloproteinase) was assessed with Western blotting. MMP activity was assessed. Coronary collateralization was graded by Rentrop scoring of angiograms. Plasminogen and collagen XVIII expression were similar between groups. Angiostatin expression trended to increase 1.24-fold (P = 0.07), and endostatin expression increased 2.02-fold in DM patients relative to ND (P = 0.02). MMP-9 expression was no different between groups, whereas MMP-2 expression decreased 1.8-fold in diabetics (P = 0.003). MMP-2 and -9 activity decreased 1.33-fold (P = 0.03) and 1.57-fold (P = 0.04), respectively, in diabetic patients. Cathepsin L expression was 1.38-fold higher in diabetic patients (P = 0.02). Coronary collateralization scores were ND 2.1 +/- 0.37 vs. DM 1.0 +/- 0.4 (P = 0.05). Myocardial endostatin expression correlated strongly with the percentage of hemoglobin A(1c) (r = 0.742, P = 0.0001). Myocardial expression of angiostatin and endostatin demonstrated significant negative linear correlations with coronary collateralization (angiostatin r = -0.531, P = 0.035, endostatin r = -0.794, P = 0.0002). Diabetic patients with CAD exhibit increased levels of the antiangiogenic proteins angiostatin and endostatin and differential regulation of the enzymes governing their production relative to ND patients. Myocardial levels of these proteins show significant correlation to coronary collateralization. These findings offer potential new therapeutic targets for enhancing proangiogenic therapy and insight into the angiogenic impairments seen in diabetes.

Increased antiangiogenic protein expression in the skeletal muscle of diabetic swine and patients

HYPOTHESIS

Antiangiogenic protein expression is increased in skeletal muscle in the setting of diabetes.

DESIGN, SETTING, AND PARTICIPANTS

In animal studies, diabetes was induced in 8 Yucatan miniswine via single alloxan injection at age 8 months, followed by skeletal muscle harvest 15 weeks later. Eight nondiabetic Yucatan miniswine served as controls. In patient studies, skeletal muscle was harvested from 11 nondiabetic patients and 10 patients with type 2 diabetes mellitus undergoing initial elective coronary artery bypass graft surgery. Skeletal muscle samples were analyzed via Western blotting and zymography for protein expression and enzyme activity. The study was performed in an academic medical center.

MAIN OUTCOME MEASURES

Skeletal muscle expression of plasminogen, collagen XVIII, angiostatin, endostatin, matrix metalloproteinases 2 and 9, and tissue inhibitor of metalloproteinase 2.

RESULTS

Skeletal muscle expression of plasminogen and collagen XVIII (precursors of angiostatin and endostatin, respectively) remained similar between nondiabetic and diabetic swine and patients. Expression of angiostatin and endostatin was increased 1.70-fold and 1.84-fold, respectively, in diabetic swine relative to control swine. Endostatin expression was increased 1.69-fold in diabetic patients relative to nondiabetic patients. Matrix metalloproteinase 2 expression and activity were significantly increased in the skeletal muscle of diabetic swine and patients.

CONCLUSIONS

Antiangiogenic protein levels are increased in the skeletal muscle in the setting of diabetes. Angiostatin, endostatin, and matrix metalloproteinases may offer novel therapeutic targets to improve collateral formation in patients with diabetes.

Gene and stem cell therapy in peripheral arterial occlusive disease

Abstract

Peripheral arterial occlusive disease (PAOD) is a manifestation of systemic atherosclerosis strongly associated with a high risk of cardiovascular morbidity and mortality. In a considerable proportion of patients with PAOD, revascularization either by endovascular means or by open surgery combined with best possible risk factor modification does not achieve limb salvage or relief of ischaemic rest pain. As a consequence, novel therapeutic strategies have been developed over the last two decades aiming to promote neovascularization and remodelling of collaterals. Gene and stem cell therapy are the main directions for clinical investigation concepts. For both, preclinical studies have shown promising results using a wide variety of genes encoding for growth factors and populations of adult stem cells, respectively. As a consequence, clinical trials have been performed applying gene and stem cell-based concepts. However, it has become apparent that a straightforward translation into humans is not possible. While several trials reported relief of symptoms and functional improvement, other trials did not confirm this early promise of efficacy. Ongoing clinical trials with an improved study design are needed to confirm the potential that gene and cell therapy may have and to prevent the gaps in our scientific knowledge that will jeopardize the establishment of angiogenic therapy as an additional medical treatment of PAOD. This review summarizes the experimental background and presents the current status of clinical applications and future perspectives of the therapeutic use of gene and cell therapy strategies for PAOD.

Increased protein and mRNA expression of endostatin in the ischemic brain tissue of rabbits after middle cerebral artery occlusion

OBJECTIVE

To explore the changes of endostatin (a strong anti-angiogenesis factor) and vascular endothelial growth factor (VEGF) in the brain tissues of rabbits following cerebral ischemia induced by middle cerebral artery occlusion (MCAO).

METHODS

Twenty-four New Zealand white rabbits were randomly divided into 5 groups: control (n = 5), sham-operation (n = 4), 2-hour ischemia (n = 5), 24-hour ischemia (n = 5), and 48-hour ischemia (n = 5). The expression of VEGF and endostatin were measured by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. In situ hybridization was used to characterize the expression of mRNA for the endostatin.

RESULTS

Both the protein (at least 50%, P < 0.01) and mRNA (at least 70%, P < 0.05) of endostatin increased significantly in the ischemic brain tissues after MCAO compared with the control group. VEGF increased at least 270% in the brain after cerebral ischemia (P < 0.05).

CONCLUSION

Cerebral ischemia leads to an up-regulation of endostatin in the brain, which is not associated with the increase of VEGF in the brain. The increase of endostatin may serve as a deleterious mechanism for ischemic injury through blocking angiogenesis.

Lowering homocysteine decreases levels and expression of VEGF(165) and endostatin

BACKGROUND

Homocysteine, vascular endothelial growth factor (VEGF), and endostatin have been implicated in angiogenesis and in the development and progression of atherothrombotic vascular disease. We sought to determine whether homocysteine modulates plasma levels of VEGF and endostatin and their expression in leukocytes in patients with peripheral arterial disease (PAD) or diabetes mellitus (DM).

MATERIALS AND METHODS

Ten patients with PAD and 15 patients with type 2 DM were evaluated before and 6 wk after oral administration of folic acid and B vitamins. Evaluation included measurements of plasma levels of homocysteine, VEGF, and endostatin by enzyme-linked immunosorbent assay and the expression of VEGF and endostatin mRNAs in leukocytes using RT-PCR. The measurements were compared with baseline findings in 12 healthy subjects.

RESULTS

Basal homocysteine (P < 0.001) and VEGF (P < 0.01) levels were elevated in all patients versus healthy subjects. Basal endostatin levels were lower in patients with PAD but were higher in patients with DM compared with healthy subjects (P < 0.001). In patients with PAD or DM, folic acid and B vitamins administration resulted in significant reduction (P < 0.001) of plasma levels of homocysteine (20.9% and 26.2%), VEGF (29.7% and 40.4%) and endostatin (9.4% and 5.7%), respectively. Moreover, VEGF and endostatin mRNA expression in leukocytes was down-regulated in all patients after B vitamins and folate treatment.

CONCLUSION

These findings demonstrate that lowering of homocysteine with B vitamins and folic acid resulted in substantial reduction of plasma levels of VEGF but minimal reduction of endostatin and in down-regulation of their expression in leukocytes in patients with PAD or DM.

Elevated vascular endothelial growth factor levels are associated with aortopulmonary collateral vessels in patients before and after the Fontan procedure

BACKGROUND

Aortopulmonary collaterals (APCs) are frequently observed before and after the Fontan procedure. However, the mechanism of the development of APCs is unknown. We hypothesized that one or several antiangiogenic and/or angiogenic growth factors might play a role in the development of APCs.

METHODS

Eighty-five patients were enrolled and divided into 3 groups (Fontan group: 30 patients after the Fontan procedure, cyanotic group: 29 patients with cyanotic heart disease, and control group: 26 patients with cyanotic heart disease after biventricular repair). We measured basic fibroblast growth factor, vascular endothelial growth factor (VEGF), hepatocyte growth factor, and endostatin at catheterization. Angiographic evaluation for the presence of APCs using a 4-point scale (grade 1: absent APCs, > or = grade 2: significantly present APCs) was performed, and the relation of the serum levels of these factors to the presence of APCs was assessed.

RESULTS

The grade of APCs significantly increased in the Fontan group, but it decreased in the control group. The serum VEGF levels were higher in the Fontan group (280 +/- 174 pg/mL) and the cyanotic group (302 +/- 245 pg/mL) than in the control group (111 +/- 91 pg/mL) (P = .0004), and they were higher in patients with APCs (383 +/- 204 pg/mL) than in those without APCs (115 +/- 65 pg/mL) (P < .0001). There was no significant difference in the serum basic fibroblast growth factor, hepatocyte growth factor, and endostatin levels between the 3 groups.

CONCLUSIONS

Aortopulmonary collaterals increase after the Fontan procedure. Serum VEGF levels are associated with the presence of APCs. Vascular endothelial growth factor may play a role in the development of APCs in patients with cyanotic heart disease and after the Fontan procedure.

Serum endostatin in the coronary circulation of patients with coronary heart disease and its relation to coronary collateral formation

The role of endostatin in coronary heart disease (CHD) is not well known. This study aimed to investigate the dynamics of endostatin, an antiangiogenic growth factor, within the coronary circulation and to elucidate its relation to coronary collateral formation in patients with CHD. We recruited 72 subjects with suspected or previously diagnosed CHD. Blood samples from the left ventricular (LV) cavity and coronary sinus (CS) were obtained during coronary angiography, and the serum concentration of endostatin was measured by enzyme-linked immunosorbent assay kits. Patients were then divided into 2 groups: the normal group (n = 15) defined as patients with atypical chest pain and no evidence of organic cardiac diseases and the CHD group (n = 57) defined as patients with >or=75% coronary stenosis at coronary angiography and chest pain on exertion. Endostatin in CS sera was significantly elevated in patients with CHD compared with normal subjects (median 79.7 [interquartile range 46.2 to 130.3] vs median 49.6 [interquartile range 29.1 to 84.5] ng/ml, p = 0.02). Spillover of endostatin (CS - LV value) from the coronary circulation in patients with CHD with severe stenosis was higher than in those with moderate stenosis (28.2 [4.8 to 48.6] vs 7.3 [-37.0 to 25.6] ng/ml, p = 0.01). In addition, endostatin production within the coronary circulation was higher in patients with poorly developed collaterals than in those with well-developed collaterals. In conclusion, endostatin is suggested to be produced from the coronary circulation in patients with CHD and may play an important role in the regulation of the growth of coronary collateral vessels.

Humoral and cellular factors responsible for coronary collateral formation

Clinical observations suggest that patients with coronary artery disease (CAD) display a marked heterogenerty in collateral formation despite similar degrees of coronary obstruction. The development of coronary collaterals helps protect the myocardium from ischemic damage, yet the factors responsible for collateral formation are poorly understood. To better understand the biochemical and cellular mechanisms of collateral artery formation, monocyte function and circulating levels of pro- and antiangiogenic factors were measured in 101 patients with angiographically assessed CAD and extensively developed (score 2, n = 33) or absent (score 0, n = 68) collateral circulations. Compared with patients with score 0, those with score 2 were slightly older and had more advanced CAD. The score 2 group was also more likely to have had a previous myocardial infarction or coronary artery bypass grafting and a family history of CAD. At the same time, there were no significant differences between groups with regard to circulating levels of vascular endothelial growth factor-A(165), platelet-derived growth factor-betabeta, fibroblast growth factor-2, fibroblast growth factor-4, hepatocyte growth factor, tumor necrosis factor-alpha, interleukin-1beta, endostatin, matrix metalloproteinase-9, promatrix metalloproteinase-1, and CD40 ligand. Monocytes isolated from patients with score 2 and 0 collateral circulations demonstrated no differences in migration assays. However, adhesion to fibrinogen and collagen was significantly higher for monocytes from patients with score 0 (p = 0.05 and 0.04, respectively). In conclusion, these data suggest that the degree of coronary collateral formation is not determined by differences in systemically measurable levels of pro- or antiangiogenic factors assessed in this study. Rather, cellular properties, such as cell adhesion, or genetic differences between patients may be the driving force for collateral development.