Endothelial progenitor cells in atherosclerosis

Asymmetric Dimethyl Arginine as a Biomarker of Atherosclerosis in Rheumatoid Arthritis

Cardiovascular disease is the main cause of morbidity and mortality in rheumatoid arthritis (RA). Despite the advent on new drugs targeting the articular manifestations, the burden of cardiovascular disease is still an unmet need in the management of RA. The pathophysiology of accelerated atherosclerosis associated to RA is not yet fully understood, and reliable and specific markers of early cardiovascular involvement are still lacking. Asymmetric dimethylarginine is gaining attention for its implication in the pathogenesis of endothelial dysfunction and as biomarkers of subclinical atherosclerosis. Moreover, the metabolic pathway of methylarginines offers possible targets for therapeutic interventions to decrease the cardiovascular risk. The purpose of this review is to describe the main causes of increased methylarginine levels in RA, their implication in accelerated atherosclerosis, the possible role as biomarkers of cardiovascular risk, and finally the available data on current pharmacological treatment.

Endothelial Progenitor Cells for Ischemic Stroke: Update on Basic Research and Application

Ischemic stroke is one of the leading causes of human death and disability worldwide. So far, ultra-early thrombolytic therapy is the most effective treatment. However, most patients still live with varying degrees of neurological dysfunction due to its narrow therapeutic time window. It has been confirmed in many studies that endothelial progenitor cells (EPCs), as a kind of adult stem cells, can protect the neurovascular unit by repairing the vascular endothelium and its secretory function, which contribute to the recovery of neurological function after an ischemic stroke. This paper reviews the basic researches and clinical trials of EPCs especially in the field of ischemic stroke and addresses the combination of EPC application with new technologies, including neurovascular intervention, synthetic particles, cytokines, and EPC modification, with the aim of shedding some light on the application of EPCs in treating ischemic stroke in the future.

Endothelial progenitor cells dysfunction and impaired tissue reparation: The missed link in diabetes mellitus development

Diabetes mellitus (DM) is considered a leading cause of premature cardiovascular (CV) mortality and morbidity in general population and in individuals with known CV disease. Recent animal and clinical studies have shown that reduced number and weak function of endothelial progenitor cells (EPCs) may not only indicate to higher CV risk, but contribute to the impaired heart and vessels reparation in patients with DM. Moreover, EPCs having a protective impact on the vasculature may mediate the functioning of other organs and systems. Therefore, EPCs dysfunction is probably promising target for DM treatment strategy, while the role of restoring of EPCs number and functionality in CV risk diminish and reduce of DM-related complications is not fully clear. The aim of the review is summary of knowledge regarding EPCs dysfunction in DM patients.

Thrombus leukocytes exhibit more endothelial cell-specific angiogenic markers than peripheral blood leukocytes do in acute coronary syndrome patients, suggesting a possibility of trans-differentiation: a comprehensive database mining study

Background

Current angiogenic therapies for cancers and cardiovascular diseases have not yet achieved expected benefits, which reflects the need for improved understanding of angiogenesis. In this study, we focused on solving the problem of whether tissues have different angiogenic potentials (APs) in physiological conditions and how angiogenesis is regulated in various disease conditions.

Methods

In healthy and diseased human and mouse tissues, we profiled the expression of 163 angiogenic genes, including transcription regulators (TRs), growth factors and receptors (GF/Rs), cytokines and chemokines (C/Cs), and proteases and inhibitors (P/Is). TRs were categorized as inflammatory, homeostatic, and endothelial cell-specific TRs, and C/Cs were categorized as pro-angiogenic, anti-angiogenic, and bi-functional C/Cs.

Results

We made the following findings: (1) the human heart, muscle, eye, pancreas, and lymph node are among the tissues with the highest APs; (2) tissues with high APs have more active angiogenic pathways and angiogenic C/C responses; (3) inflammatory TRs dominate regulation of all angiogenic C/Cs; homeostatic TRs regulate all to a lower extent, while endothelial cell-specific TRs mainly regulate pro-angiogenic and bi-functional C/Cs; (4) tissue AP is positively correlated with the expression of oxygen sensors PHD2 and HIF1B, VEGF pathway gene VEGFB, and stem cell gene SOX2; (5) cancers of the digestive system tend to have increased angiogenesis dominated by endothelial cell-specific pro-angiogenic pathways, while lung cancer and prostate cancer have significantly decreased angiogenesis; and (6) endothelial cell-specific pro-angiogenic pathways are significantly increased in thrombus-derived leukocytes in patients with acute coronary artery disease.

Conclusions

Our results demonstrate that thrombus-derived leukocytes express more endothelial cell-specific angiogenic markers to directly promote angiogenesis after myocardial infarction and that certain solid tumors may be more sensitive to anti-angiogenic therapies than others.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0440-0) contains supplementary material, which is available to authorized users.

HMGB1 induces endothelial progenitor cells apoptosis via RAGE-dependent PERK/eIF2α pathway

Studies have demonstrated that the high-mobility group 1B protein (HMGB1) could regulate endothelial progenitor cell (EPC) homing, but the effect of HMGB1 on EPC apoptosis and associated mechanisms are still unclear. The aim of this study was to investigate the effects of HMGB1 on EPC apoptosis and the possible involvement of the endoplasmic reticulum (ER) stress pathway. EPC apoptosis was determined by flow cytometry. The expressions of PERK, eIF2α, and CHOP were detected by western blotting. Additionally, the effects of PERK shRNA on the biological behaviors of EPCs were assessed. Our results showed that incubation of EPCs with HMGB1 (0.1-1 μg/ml) for 12-48 h induced apoptosis as well as activated ER stress transducers, as assessed by up-regulating PERK protein expression and eIF2α phosphorylation in a dose or time-dependent manner. Moreover, HMGB1-mediated EPC apoptosis and CHOP expression were dramatically suppressed by PERK shRNA or a specific eIF2α inhibitor (salubrinal). Importantly, a blocking antibody specifically targeted against RAGE (anti-RAGE antibody) markedly inhibited HMGB1-induced EPC apoptosis and ER stress marker protein (PERK, eIF2α, and CHOP) expression levels. Our novel findings suggest that HMGB1 triggered EPC apoptosis in a manner of RAGE-mediated activation of the PERK/eIF2α pathway.

Oxidized low-density lipoprotein decreases VEGFR2 expression in HUVECs and impairs angiogenesis

Atherosclerosis (AS), which is triggered by endothelial cell injury, evolves into a chronic inflammatory disease. Oxidized low-density lipoprotein (ox-LDL) is an important risk factor for the development of atherosclerosis; ox-LDL induces atherosclerotic plaque formation via scavenging receptors. The present study used ox-LDL-treated human umbilical vein endothelial cells (HUVECs) to investigate the effect of ox-LDL on angiogenesis. ox-LDL decreased HUVEC proliferation by MTT, induced apoptosis by Annexin V-fluorescein isothiocyanate (FITC) staining and markedly suppressed HUVEC tube formation by the Matrigel assay in a dose-dependent manner. Angiogenesis has been correlated with monocyte invasion, plaque instability and atherosclerotic lesion formation. In addition, ox-LDL induced the overproduction of reactive oxygen species using DCFH-DA staining and increased caspase-3 activity. Vascular endothelial growth factor receptor 2 (VEGFR2) were detected by quantitative polymerase chain reaction and western blot analysis and has previously been observed to have a key role in angiogenesis. Furthermore, the present study demonstrated that the abundance of VEGFR2 was decreased in ox-LDL-treated HUVECs. These results suggested that ox-LDL impairs angiogenesis via VEGFR2 degradation, thus suggesting that VEGFR2 may be involved in adaptation to oxidative stress and AS.

Vasoregression: A Shared Vascular Pathology Underlying Macrovascular And Microvascular Pathologies?

Vasoregression is a common phenomenon underlying physiological vessel development as well as pathological microvascular diseases leading to peripheral neuropathy, nephropathy, and vascular oculopathies. In this review, we describe the hallmarks and pathways of vasoregression. We argue here that there is a parallel between characteristic features of vasoregression in the ocular microvessels and atherosclerosis in the larger vessels. Shared molecular pathways and molecular effectors in the two conditions are outlined, thus highlighting the possible systemic causes of local vascular diseases. Our review gives us a system-wide insight into factors leading to multiple synchronous vascular diseases. Because shared molecular pathways might usefully address the diagnostic and therapeutic needs of multiple common complex diseases, the literature analysis presented here is of broad interest to readership in integrative biology, rational drug development and systems medicine.

Single- and double-walled carbon nanotubes enhance atherosclerogenesis by promoting monocyte adhesion to endothelial cells and endothelial progenitor cell dysfunction

BACKGROUND

The use of carbon nanotubes has increased lately. However, the cardiovascular effect of exposure to carbon nanotubes remains elusive. The present study investigated the effects of pulmonary exposure to single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) on atherosclerogenesis using normal human aortic endothelial cells (HAECs) and apolipoprotein E-deficient (ApoE^-/-) mice, a model of human atherosclerosis.

METHODS

HAECs were cultured and exposed to SWCNTs or DWCNTs for 16 h. ApoE^-/- mice were exposed to SWCNTs or DWCNTs (10 or 40 μg/mouse) once every other week for 10 weeks by pharyngeal aspiration.

RESULTS

Exposure to CNTs increased the expression level of adhesion molecule (ICAM-1) and enhanced THP-1 monocyte adhesion to HAECs. ApoE^-/- mice exposed to CNTs showed increased plaque area in the aorta by oil red O staining and up-regulation of ICAM-1 expression in the aorta, compared with vehicle-treated ApoE^-/- mice. Endothelial progenitor cells (EPCs) are mobilized from the bone marrow into the circulation and subsequently migrate to the site of endothelial damage and repair. Exposure of ApoE^-/- mice to high-dose SWCNTs or DWCNTs reduced the colony-forming units of EPCs in the bone marrow and diminished their migration function.

CONCLUSION

The results suggested that SWCNTs and DWCNTs enhanced atherosclerogenesis by promoting monocyte adhesion to endothelial cells and inducing EPC dysfunction.

Addition of aspirin to a fish oil-rich diet decreases inflammation and atherosclerosis in ApoE-null mice

Aspirin (ASA) is known to alter the production of potent inflammatory lipid mediators, but whether it interacts with omega-3 fatty acids (FAs) from fish oil to affect atherosclerosis has not been determined. The goal was to investigate the impact of a fish oil-enriched diet alone and in combination with ASA on the production of lipid mediators and atherosclerosis. ApoE(-/-) female mice were fed for 13weeks one of the four following diets: omega-3 FA deficient (OD), omega-3 FA rich (OR) (1.8g omega-3 FAs/kg·diet per day), omega-3 FA rich plus ASA (ORA) (0.1g ASA/kg·diet per day) or an omega-3 FA deficient plus ASA (ODA) with supplement levels equivalent to human doses. Plasma lipids, atherosclerosis, markers of inflammation, hepatic gene expression and aortic lipid mediators were determined. Hepatic omega-3 FAs were markedly higher in OR (9.9-fold) and ORA (7-fold) groups. Mice in both OR and ORA groups had 40% less plasma cholesterol in very low-density lipoprotein-cholesterol and low-density lipoprotein fractions, but aortic plaque area formation was only significantly lower in the ORA group (5.5%) compared to the OD group (2.5%). Plasma PCSK9 protein levels were approximately 70% lower in the OR and ORA groups. Proinflammatory aortic lipid mediators were 50%-70% lower in the ODA group than in the OD group and more than 50% lower in the ORA group. In summary, less aortic plaque lesions and aortic proinflammatory lipid mediators were observed in mice on the fish oil diet plus ASA vs. just the fish oil diet.

Prognostic relevance of circulating endothelial progenitor cells in patients with chronic heart failure

Novel strategies for a tailored risk prediction in chronic heart failure (CHF) are crucial to identify patients at very high risk for an improved patient management and to specify treatment regimens. Endothelial progenitor cells (EPCs) are an important endogenous repair mechanism with the ability to counteract endothelial injury and the possibility of new vessel formation. We hypothesised that exhaustion of circulating EPCs may be a suitable prognostic biomarker in patients with CHF. EPCs, defined as CD34+CD45dimKDR+ cells, were analysed using fluorescence-activated cell sorting. EPCs were measured in 185 patients with CHF including 87 (47 %) patients with ischaemic aetiology and 98 (53 %) patients with non-ischaemic CHF and followed for a median time of 2.7 years. During this period, 34.7 % of patients experienced the primary study endpoint all-cause mortality. EPC count was a significant and independent inverse predictor of mortality with an hazard ratio hazard ratio (HR) per increase of one standard deviation (1-SD) of 0.47 (95 % confidence interval [CI]: 0.35-0.61; p<0.001) and remained significant after multivariable adjustment for a comprehensive set of cardiovascular risk factors and potential confounders with a HR per 1-SD of 0.54 (95 % CI: 0.4-0.73; p<0.001). EPCs further demonstrated additional prognostic information indicated by improvements in C-statistic, net reclassification index and integrated discrimination increment. In conclusion, in our study circulating EPCs turned out as strong and independent inverse predictors of mortality underlining the importance of an impaired endothelial repair mechanism in the pathophysiology and progression of CHF.

Mitochondrial Reactive Oxygen Species Mediate Lysophosphatidylcholine-Induced Endothelial Cell Activation

OBJECTIVE

Hyperlipidemia-induced endothelial cell (EC) activation is considered as an initial event responsible for monocyte recruitment in atherogenesis. However, it remains poorly defined what is the mechanism underlying hyperlipidemia-induced EC activation. Here, we tested a novel hypothesis that mitochondrial reactive oxygen species (mtROS) serve as signaling mediators for EC activation in early atherosclerosis.

APPROACH AND RESULTS

Metabolomics and transcriptomics analyses revealed that several lysophosphatidylcholine (LPC) species, such as 16:0, 18:0, and 18:1, and their processing enzymes, including Pla2g7 and Pla2g4c, were significantly induced in the aortas of apolipoprotein E knockout mice during early atherosclerosis. Using electron spin resonance and flow cytometry, we found that LPC 16:0, 18:0, and 18:1 induced mtROS in primary human aortic ECs, independently of the activities of nicotinamide adenine dinucleotide phosphate oxidase. Mechanistically, using confocal microscopy and Seahorse XF mitochondrial analyzer, we showed that LPC induced mtROS via unique calcium entry-mediated increase of proton leak and mitochondrial O2 reduction. In addition, we found that mtROS contributed to LPC-induced EC activation by regulating nuclear binding of activator protein-1 and inducing intercellular adhesion molecule-1 gene expression in vitro. Furthermore, we showed that mtROS inhibitor MitoTEMPO suppressed EC activation and aortic monocyte recruitment in apolipoprotein E knockout mice using intravital microscopy and flow cytometry methods.

CONCLUSIONS

ATP synthesis-uncoupled, but proton leak-coupled, mtROS increase mediates LPC-induced EC activation during early atherosclerosis. These results indicate that mitochondrial antioxidants are promising therapies for vascular inflammation and cardiovascular diseases.

Myocardial Ischemia Induces SDF-1α Release in Cardiac Surgery Patients

In the present observational study, we measured serum levels of the chemokine stromal cell-derived factor-1α (SDF-1α) in 100 patients undergoing cardiac surgery with cardiopulmonary bypass at seven distinct time points including preoperative values, myocardial ischemia, reperfusion, and the postoperative course. Myocardial ischemia triggered a marked increase of SDF-1α serum levels whereas cardiac reperfusion had no significant influence. Perioperative SDF-1α serum levels were influenced by patients' characteristics (e.g., age, gender, aspirin intake). In an explorative analysis, we observed an inverse association between SDF-1α serum levels and the incidence of organ dysfunction. In conclusion, time of myocardial ischemia was identified as the key stimulus for a significant upregulation of SDF-1α, indicating its role as a marker of myocardial injury. The inverse association between SDF-1α levels and organ dysfunction association encourages further studies to evaluate its organoprotective properties in cardiac surgery patients.

Abnormal phosphorylation of Tie2/Akt/eNOS signaling pathway and decreased number or function of circulating endothelial progenitor cells in prehypertensive premenopausal women with diabetes mellitus

BACKGROUNDS

The number and activity of circulating endothelial progenitor cells (EPCs) in prehypertension is preserved in premenopausal women. However, whether this favorable effect still exists in prehypertensive premenopausal women with diabetes is not clear.

METHODS

This study compared the number and functional activity of circulating EPCs in normotensive or prehypertensive premenopausal women without diabetes mellitus and normotensive or prehypertensive premenopausal women with diabetes mellitus, evaluated the vascular endothelial function in each groups, and investigated the possible underlying mechanism.

RESULTS

We found that compared with normotensive premenopausal women, the number and function of circulating EPCs, as well as endothelial function evaluated by flow-mediated dilatation (FMD) in prehypertensive premenopausal women were preserved. In parallel, the Tie2/Akt/eNOS signaling pathway and the plasma NO level or NO secretion of circulating EPCs in prehypertensive premenopausal women was also retained. However, in presence of normotension or prehypertension with diabetes mellitus, the number or function of circulating EPCs and FMD in premenopausal women decreased. Similarly, the phosphorylation of Tie2/Akt/eNOS signaling pathway and the plasma NO level or NO secretion of circulating EPCs was reduced in prehypertension premenopausal with diabetes mellitus.

CONCLUSION

The present findings firstly demonstrate that the unfavorable effects of diabetes mellitus on number and activity of circulating EPCs in prehypertension premenopausal women, which is at least partially related to the abnormal phosphorylation of Tie2/Akt/eNOS signaling pathway and subsequently reduced nitric oxide bioavailability. The Tie2/Akt/eNOS signaling pathway may be a potential target of vascular protection in prehypertensive premenopausal women with diabetes mellitus.

On the Roles of the Transient Receptor Potential Canonical 3 (TRPC3) Channel in Endothelium and Macrophages: Implications in Atherosclerosis

In the cardiovascular and hematopoietic systems the Transient Receptor Potential Canonical 3 (TRPC3) channel has a well-recognized role in a number of signaling mechanisms that impact the function of diverse cells and tissues in physiology and disease. The latter includes, but is not limited to, molecular and cellular mechanisms associated to the pathogenesis of cardiac hypertrophy, hypertension and endothelial dysfunction. Despite several of these functions being closely related to atherorelevant mechanisms, the potential roles of TRPC3 in atherosclerosis, the major cause of coronary artery disease, have remained largely unexplored. Over recent years, a series of studies from the authors' laboratory revealed novel functions of TRPC3 in mechanisms related to endothelial inflammation, monocyte adhesion to endothelium and survival and apoptosis of macrophages. The relevance of these new TRPC3 functions to atherogenesis has recently began to receive validation through studies in mouse models of atherosclerosis with conditional gain or loss of TRPC3 function. This chapter summarizes these novel findings and provides a discussion of their impact in the context of atherosclerosis, in an attempt to delineate a framework for further exploration of this terra incognita in the TRPC field.

Smoking impairs and circulating stem cells favour the protective effect of the T allele of the connexin37 gene in ischemic heart disease--A multinational study

BACKGROUND

The connexin 37 (Cx37) gene is considered to be a candidate gene for ischemic heart disease (IHD). We analyzed the association between the C1019 > T (Pro319 > Ser) variant of the Cx37 gene and IHD in patients in the Czech Republic, Croatia, Hungary and Romania with regard to the presence/absence of selected cardiovascular risk factors (RF). In a complementary study, we analyzed the association between the Cx37 gene and circulating stem and endothelial progenitor cells in healthy women.

METHODS

The study population comprised 2396 patients (663 women) with IHD. The control population comprised 2476 subjects (1, 337 women). Additionally, in 662 healthy women, the association between the Cx37 gene and circulating stem and endothelial progenitor cells was analyzed.

RESULTS

The strongest protective effect of the Cx37 T allele was detected in non-smoking patients without diabetes mellitus and hypertension (OR 0.610, 95% CI 0.377-0.990); a similar effect was found in non-smoking men (OR 0.781, 95% CI 0.628-0.971); weaker effect was found in non-smoking women (OR 0.768, 95% CI 0.560-1.050). In non-smoking healthy women, stem cells were significantly higher in TT than in CT and CC carriers (p for trend 0.011). Additionally, non-smoking TT carriers had significantly higher number of stem cells than past and current smoking TT carriers (p for trend = 0.006); no such trend was found in CT and CC carriers.

CONCLUSIONS

The protective effect of the T allele of the Cx37 gene might be strongly modified by smoking; in women, this effect could be mediated through stem cells.

Caspase-1 mediates hyperlipidemia-weakened progenitor cell vessel repair

Caspase-1 activation senses metabolic danger-associated molecular patterns (DAMPs) and mediates the initiation of inflammation in endothelial cells. Here, we examined whether the caspase-1 pathway is responsible for sensing hyperlipidemia as a DAMP in bone marrow (BM)-derived Stem cell antigen-1 positive (Sca-(1+)) stem/progenitor cells and weakening their angiogenic ability. Using biochemical methods, gene knockout, cell therapy and myocardial infarction (MI) models, we had the following findings: 1) Hyperlipidemia induces caspase-1 activity in mouse Sca-(1+) progenitor cells in vivo; 2) Caspase-1 contributes to hyperlipidemia-induced modulation of vascular cell death-related gene expression in vivo; 3) Injection of Sca-1+ progenitor cells from caspase-1(-/-) mice improves endothelial capillary density in heart and decreases cardiomyocyte death in a mouse model of MI; and 4) Caspase-1(-/-) Sca-(1+) progenitor cell therapy improves mouse cardiac function after MI. Our results provide insight on how hyperlipidemia activates caspase-1 in Sca-(1+) progenitor cells, which subsequently weakens Sca-(1+) progenitor cell repair of vasculature injury. These results demonstrate the therapeutic potential of caspase-1 inhibition in improving progenitor cell therapy for MI.

Enhancing endothelial progenitor cell for clinical use

Circulating endothelial progenitor cells (EPCs) have been demonstrated to correlate negatively with vascular endothelial dysfunction and cardiovascular risk factors. However, translation of basic research into the clinical practice has been limited by the lack of unambiguous and consistent definitions of EPCs and reduced EPC cell number and function in subjects requiring them for clinical use. This article critically reviews the definition of EPCs based on commonly used protocols, their value as a biomarker of cardiovascular risk factor in subjects with cardiovascular disease, and strategies to enhance EPCs for treatment of ischemic diseases.

MIF and CXCL12 in Cardiovascular Diseases: Functional Differences and Similarities

Coronary artery disease (CAD) as part of the cardiovascular diseases is a pathology caused by atherosclerosis, a chronic inflammatory disease of the vessel wall characterized by a massive invasion of lipids and inflammatory cells into the inner vessel layer (intima) leading to the formation of atherosclerotic lesions; their constant growth may cause complications such as flow-limiting stenosis and plaque rupture, the latter triggering vessel occlusion through thrombus formation. Pathophysiology of CAD is complex and over the last years many players have entered the picture. One of the latter being chemokines (small 8-12 kDa cytokines) and their receptors, known to orchestrate cell chemotaxis and arrest. Here, we will focus on the chemokine CXCL12, also known as stromal cell-derived factor 1 (SDF-1) and the chemokine-like function chemokine, macrophage migration-inhibitory factor (MIF). Both are ubiquitously expressed and highly conserved proteins and play an important role in cell homeostasis, recruitment, and arrest through binding to their corresponding chemokine receptors CXCR4 (CXCL12 and MIF), ACKR3 (CXCL12), and CXCR2 (MIF). In addition, MIF also binds to the receptor CD44 and the co-receptor CD74. CXCL12 has mostly been studied for its crucial role in the homing of (hematopoietic) progenitor cells in the bone marrow and their mobilization into the periphery. In contrast to CXCL12, MIF is secreted in response to diverse inflammatory stimuli, and has been associated with a clear pro-inflammatory and pro-atherogenic role in multiple studies of patients and animal models. Ongoing research on CXCL12 points at a protective function of this chemokine in atherosclerotic lesion development. This review will focus on the role of CXCL12 and MIF and their differences and similarities in CAD of high risk patients.

Dysfunctional endothelial progenitor cells in cardiovascular diseases: role of NADPH oxidase

Endothelial progenitor cells (EPCs) play a critical role in maintenance of the endothelial integrity and vascular homeostasis, as well as in neovascularization. Dysfunctional EPCs are believed to contribute to the endothelial dysfunction and are closely related to the development of various cardiovascular diseases, such as hypertension, hyperlipidemia, and stroke. However, the underlying mechanisms of EPC dysfunction are complicated and remain largely elusive. Recent studies have demonstrated that reactive oxygen species (ROS) are key factors that involve in modulation of stem and progenitor cell function under various physiologic and pathologic conditions. It has been shown that NADPH oxidase (NOX)-derived ROS are the major sources of ROS in cardiovascular system. Accumulating evidence suggests that NOX-mediated oxidative stress can modulate EPC bioactivities, such as mobilization, migration, and neovascularization, and that inhibition of NOX has been shown to improve EPC functions. This review summarized recent progress in the studies on the correlation between NOX-mediated EPC dysfunction and cardiovascular diseases.

Effects of olmesartan on endothelial progenitor cell mobilization and function in carotid atherosclerosis

BACKGROUND

Olmesartan is a type of angiotensin II receptor inhibitor that can reduce the incidence of cardiovascular events. However, its role in the function of endothelial progenitor cells in atherosclerosis patients is still unclear. Our study aimed to explore the effects and mechanism of olmesartan on endothelial progenitor cell mobilization and function in carotid atherosclerosis.

MATERIAL/METHODS

Forty carotid atherosclerosis patients were enrolled. Patients were administrated olmesartan 20 mg/day for 3 months. Flow cytometry was used for counting circulating endothelial progenitor cells; colorimetric method was used to measure the serum levels of endothelial nitric oxide synthase and nitric oxide. Cell migration, adhesion, and proliferation capacity, and related signaling pathway were also analyzed. Spearman rank correlation analysis was used to investigate the influence of olmesartan on endothelial progenitor cells and clinical characteristics (e.g., sex, age, blood pressure).

RESULTS

Compared with the control group, the number of circulating endothelial progenitor cells was significantly decreased. Olmesartan can increase circulating endothelial progenitor cells number and the serum levels of eNOS and NO. Furthermore, it can improve cell migration, adhesion, and proliferation capacities. Spearman rank correlation analysis showed there is no relationship between olmesartan promotion effects on endothelial progenitor cell mobilization and the clinical characteristics (P>0.05). P-eNOS and P-Akt expression can be unregulated by RNH-6270 treatment and blocked by LY294002.

CONCLUSIONS

Olmesartan can effectively promote the endothelial progenitor cells mobilization and improve their function in patients with carotid atherosclerosis, independent of basic characteristics. This process relies on the PI3K/Akt/eNOS signaling pathway.

Circulating endothelial progenitor cells and the risk of vascular events after ischemic stroke

Background and Purpose

We evaluated the hypothesis that the number of circulating EPC could be associated with the risk of stroke recurrence (SR) or vascular events (VE) after an ischemic stroke.

Methods

We studied prospectively consecutive patients with cerebral infarction within the first 48 hours after the onset. We recorded demographic factors, vascular risk factors, previous Rankin scale (RS) score, and etiology. We analyzed EPC counts by flow cytometry in blood collected at day 7 and defined EPC as CD34+/CD133+/KDR+ cells. Mean follow-up was 29.3 ± 16 months. We evaluated SR as well as VE. Patients were classified as to the presence or absence of EPC in the circulation (either EPC+ or EPC-). Bivariate analyses, Kaplan-Meier survival curves and Cox regression models were used.

Results

We included 121 patients (mean age 70.1±12.6 years; 65% were men). The percentage of EPC+ patients was 47.1%. SR occurred in 12 (9.9%) and VE in 18 (14.9%) patients. SR was associated significantly with a worse prior RS score, previous stroke and etiology, but not with EPC count. VE were associated significantly with EPC-, worse prior RS score, previous stroke, high age, peripheral artery disease and etiology. Cox regression model showed that EPC- (HR 7.07, p=0.003), age (HR 1.08, p=0.004) and a worse prior RS score (HR 5.8, p=0.004) were associated significantly with an increased risk of VE.

Conclusions

The absence of circulating EPC is not associated with the risk of stroke recurrence, but is associated with an increased risk of future vascular events.

Endothelial progenitor cells in ischemic stroke: an exploration from hypothesis to therapy

As the population ages and lifestyles change in concordance, the number of patients suffering from ischemic stroke and its associated disabilities is increasing. Studies on determining the relationship between endothelial progenitor cells (EPCs) and ischemic stroke have become a new hot spot and have reported that EPCs may protect the brain against ischemic injury, promote neurovascular repair, and improve long-term neurobehavioral outcomes. More importantly, they introduce a new perspective for prognosis assessment and therapy of ischemic stroke. However, EPCs’ origin, function, influence factors, injury repair mechanisms, and cell-based therapy strategies remain controversial. Particularly, research conducted to date has less clinical studies than pre-clinical experiments on animals. In this review, we summarized and analyzed the current understanding of basic characteristics, influence factors, functions, therapeutic strategies, and disadvantages of EPCs as well as the regulation of inflammatory factors involved in the function and survival of EPCs after ischemic stroke. Identifying potential therapeutic effects of EPCs in ischemic stroke will be a challenging but an incredibly important breakthrough in neurology, which may bring promise for patients with ischemic stroke.

Reduction of Store-Operated Ca(2+) Entry Correlates with Endothelial Progenitor Cell Dysfunction in Atherosclerotic Mice

The dysfunction of endothelial progenitor cells (EPCs) has been shown to prevent endothelial repair during the development of atherosclerosis (AS). Previous studies have revealed that store-operated calcium entry (SOCE) is an important factor in regulating EPC functions. However, whether this is also the mechanism in AS has not been elucidated. Therefore, we evaluated the role of SOCE in EPCs isolated from an atherosclerotic mouse model. Atheromatous plaques were more frequent in the aortas of ApoE(-/-) mice fed a high-fat diet for 16 weeks compared with controls, and the proliferative and migratory activities of atherosclerotic EPCs were significantly decreased. Accordingly, SOCE amplitude, as well as spontaneous or VEGF-induced Ca(2+) oscillations, decreased in atherosclerotic EPCs. These results may be associated with the downregulated expression of Stim1, Orai1, and TRPC1, which are major mediators of SOCE. In addition, eNOS expression and phosphorylation at Ser(1177), which are critical regulators of EPC function, were markedly reduced in the atherosclerotic EPCs. The impairment of eNOS activity could also be induced by using an SOCE inhibitor or by Stim1 gene silencing, indicating a link between the activities of eNOS and SOCE in AS. Furthermore, decreased SOCE function inhibited EPC proliferation and migration in vitro. In conclusion, our results showed that the reduction of SOCE induced EPC dysfunction during AS, potentially through downregulation of store-operated calcium channel (SOCC) components and impaired eNOS activity. Approaches aimed at reestablishing SOCE activity may thus improve the function of EPCs during AS.

Sirtuin 6 expression and inflammatory activity in diabetic atherosclerotic plaques: effects of incretin treatment

The role of sirtuin 6 (SIRT6) in atherosclerotic progression of diabetic patients is unknown. We evaluated SIRT6 expression and the effect of incretin-based therapies in carotid plaques of asymptomatic diabetic and nondiabetic patients. Plaques were obtained from 52 type 2 diabetic and 30 nondiabetic patients undergoing carotid endarterectomy. Twenty-two diabetic patients were treated with drugs that work on the incretin system, GLP-1 receptor agonists, and dipeptidyl peptidase-4 inhibitors for 26 ± 8 months before undergoing the endarterectomy. Compared with nondiabetic plaques, diabetic plaques had more inflammation and oxidative stress, along with a lesser SIRT6 expression and collagen content. Compared with non-GLP-1 therapy-treated plaques, GLP-1 therapy-treated plaques presented greater SIRT6 expression and collagen content, and less inflammation and oxidative stress, indicating a more stable plaque phenotype. These results were supported by in vitro observations on endothelial progenitor cells (EPCs) and endothelial cells (ECs). Indeed, both EPCs and ECs treated with high glucose (25 mmol/L) in the presence of GLP-1 (100 nmol/L liraglutide) presented a greater SIRT6 and lower nuclear factor-κB expression compared with cells treated only with high glucose. These findings establish the involvement of SIRT6 in the inflammatory pathways of diabetic atherosclerotic lesions and suggest its possible positive modulation by incretin, the effect of which is associated with morphological and compositional characteristics of a potential stable plaque phenotype.

Mobilization of sca1/flk-1 positive endothelial progenitor cells declines in apolipoprotein E-deficient mice with a high-fat diet

BACKGROUND

Atherosclerosis features a deterioration of the endothelial layer in all stages. Restoration of the endothelium is associated with circulating stem cell antigen 1 (sca1) and vascular endothelial growth factor receptor type 2 (flk-1) positive endothelial progenitor cells (EPCs). We investigated whether EPC production and/or a mobilization from bone marrow are reduced in severe atherosclerosis.

METHODS AND RESULTS

EPCs in peripheral blood were diminished in ApoE-/- mice with high-fat diet (HFD) whereas bone marrow levels of these cells were not significantly altered compared to controls. In situ perfusion of the hind limbs demonstrated that EPC mobilization was reduced compared to ApoE-/- mice with normal chow, although increased plasma stromal cell-derived factor (SDF) 1α and responsivity suggested a mobilizing stimulus. The proliferation of sca1/flk-1 positive cells showed no functional impairment. EPCs could not only be significantly mobilized from the bone marrow through the application of granulocyte colony stimulating factor (GCSF), but also led by trend to a depletion of the bone marrow pool. GCSF levels in plasma were equal in ApoE-/- mice with normal chow or HFD, which excluded a decline in GCSF production.

CONCLUSION

The capability of the bone marrow pool to adapt the proliferation and mobilization of sca1/flk-1 positive EPCs seems overstrained in ApoE-/- mice with a HFD.

Successful matrix guided tissue regeneration of decellularized pulmonary heart valve allografts in elderly sheep

In vivo repopulation of decellularized allografts with recipient cells leads to a positive remodeling of the graft matrix in juvenile sheep. In light of the increasing number of heart valve replacements among older patients (>65 years), this study focused on the potential for matrix-guided tissue regeneration in elderly sheep. Pulmonary valve replacement was performed in seven-year old sheep using decellularized (DV), decellularized and CCN1-coated (RV), or decellularized and in vitro reendothelialized pulmonary allografts (REV) (n=6, each group). CCN1 coating was applied to support re-endothelialization. In vitro re-endothelialization was conducted with endothelial-like cells derived from peripheral blood. Echocardiograms of all grafts showed adequate graft function after implantation and at explantation 3 or 6 months later. All explants were macroscopically free of thrombi at explantation, and revealed repopulation of the allografts on the adventitial side of valvular walls and proximal in the cusps. Engrafted cells expressed vimentin, sm α-actin, and myosin heavy chain 2, while luminal cell lining was positive for vWF and eNOS. Cellular repopulation of valvular matrix demonstrates the capacity for matrix-guided regeneration even in elderly sheep but is not improved by in vitro endothelialization, confirming the suitability of decellularized matrix for heart valve replacement in older individuals.

Ambient fine particulate matter induces apoptosis of endothelial progenitor cells through reactive oxygen species formation

BACKGROUND/AIMS

Bone marrow (BM)-derived endothelial progenitor cells (EPCs) play a critical role in angiogenesis and vascular repair. Some environmental insults, like fine particulate matter (PM) exposure, significantly impair cardiovascular functions. However, the mechanisms for PM-induced adverse effects on cardiovascular system remain largely unknown. The present research was to study the detrimental effects of PM on EPCs and explore the potential mechanisms.

METHODS

PM was intranasal-distilled into male C57BL/6 mice for one month. Flow cytometry was used to measure the number of EPCs, apoptosis level of circulating EPCs and intracellular reactive oxygen species (ROS) formation. Serum TNF-α and IL-1β were measured using ELISA. To determine the role of PM-induced ROS in EPC apoptosis, PM was co-administrated with the antioxidant N-acetylcysteine (NAC) in wild type mice or used in a triple transgenic mouse line (TG) with overexpression of antioxidant enzyme network (AON) composed of superoxide dismutase (SOD)1, SOD3, and glutathione peroxidase (Gpx-1) with decreased in vivo ROS production.

RESULTS

PM treatment significantly decreased circulating EPC population, promoted apoptosis of EPCs in association with increased ROS production and serum TNF-α and IL-1β levels, which could be effectively reversed by either NAC treatment or overexpression of AON.

CONCLUSION

PM exposure significantly decreased circulating EPCs population due to increased apoptosis via ROS formation in mice.

Circulating CD133+ CD34+ progenitor cells and plasma stromal-derived factor-1alpha: predictive role in ischemic stroke patients

Circulating progenitor cells and stromal-derived factor-1alpha (SDF-1α) have been suggested to participate in tissue repair after ischemic injury. However, the predictive role of circulating CD133+ CD34+ progenitors and plasma SDF-1α in ischemic stroke (IS) patients remains unknown. In this study, we recruited 95 acute IS patients, 40 at-risk subjects, and 30 normal subjects. The National Institutes of Health Stroke Scale (NIHSS), infarct volume, and carotid intima-media thickness (IMT) were determined at day 1 and the modified Rankin scale (mRS) of functional outcome was assessed at day 21. The levels of circulating CD133+ CD34+ cells and plasma SDF-1α were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. Our data showed that: (1) the levels of CD133+ CD34+ cells were lower in at-risk subjects and IS patients at admission (day 1) when compared with normal controls; (2) the day 1 level of CD133+ CD34+ cells varied in IS subgroups and inversely correlated with NIHSS and carotid IMT and the level of SDF-1α inversely correlated with NIHSS and infarct volume; (3) the increment rates of circulating CD133+ CD34+ cells and plasma SDF-1α within the first week were correlated; and (4) patients with a higher level of CD133+ CD34+ cells at day 7 had a low mRS. The increased rate of CD133+ CD34+ cells in the first week was inversely associated with mRS. In conclusion, our findings demonstrate that the circulating CD133+ CD34+ progenitor cells and plasma SDF-1α can be used as predictive parameters for IS severity and outcome.

Loss of endothelial-ARNT in adult mice contributes to dampened circulating proangiogenic cells and delayed wound healing

The recruitment and homing of circulating bone marrow-derived cells include endothelial progenitor cells (EPCs) that are critical to neovascularization and tissue regeneration of various vascular pathologies. We report here that conditional inactivation of hypoxia-inducible factor's (HIF) transcriptional activity in the endothelium of adult mice (Arnt(ΔiEC) mice) results in a disturbance of infiltrating cells, a hallmark of neoangiogenesis, during the early phases of wound healing. Cutaneous biopsy punches show distinct migration of CD31(+) cells into wounds of control mice by 36 hours. However, a significant decline in numbers of infiltrating cells with immature vascular markers, as well as decreased transcript levels of genes associated with their expression and recruitment, were identified in wounds of Arnt(ΔiEC) mice. Matrigel plug assays further confirmed neoangiogenic deficiencies alongside a reduction in numbers of proangiogenic progenitor cells from bone marrow and peripheral blood samples of recombinant vascular endothelial growth factor-treated Arnt(ΔiEC) mice. In addition to HIF's autocrine requirements in endothelial cells, our data implicate that extrinsic microenvironmental cues provided by endothelial HIF are pivotal for early migration of proangiogenic cells, including those involved in wound healing.

Resistance exercise increases endothelial progenitor cells and angiogenic factors

INTRODUCTION

Bone marrow-derived endothelial progenitor cells (EPC) are involved in vascular growth and repair. They increase in the circulation after a single bout of aerobic exercise, potentially related to muscle ischemia. Muscular endurance resistance exercise (MERE) bouts also have the potential to induce muscle ischemia if appropriately structured.

PURPOSE

The objective of this study is to determine the influence of a single bout of MERE on circulating EPC and related angiogenic factors.

METHODS

Thirteen trained men age 22.4 ± 0.5 yr (mean ± SEM) performed a bout of MERE consisting of three sets of six exercises at participants' 15-repetition maximum without resting between repetitions or exercises. The MERE bout duration was 12.1 ± 0.6 min. Blood lactate and HR were 11.9 ± 0.9 mmol·L and 142 ± 5 bpm, respectively, at the end of MERE. Blood was sampled preexercise and at 10 min, 2 h, and 24 h postexercise.

RESULTS

Circulating EPC and serum concentrations of vascular endothelial growth factors (VEGF-A, VEGF-C, and VEGF-D), granulocyte colony stimulating factor, soluble Tie-2, soluble fms-like tyrosine kinase-1, and matrix metalloproteinases (MMP-1, MMP-2, MMP-3, MMP-9, and MMP-9) were higher (P < 0.05) in the postexercise period. Circulating EPC levels were unchanged at 10 min postexercise but higher at 2 h postexercise (P < 0.05). The concentration of most angiogenic factors and metalloproteinases were higher at 10 min postexercise (VEGF-A, +38%; VEGF-C, +40%; VEGF-D, +9%; soluble Tie-2, +15%; soluble fms-like tyrosine kinase-1, +24%; MMP-1, +62%; MMP-2, +3%; MMP-3, +54%; and MMP-9, +45%; all P < 0.05). Soluble E-selectin was lower (P < 0.05) at 2 and 24 h postexercise, with endothelial microparticles and thrombomodulin unchanged.

CONCLUSIONS

Short intense bouts of MERE can trigger increases in circulating EPC and related angiogenic factors, potentially contributing to vascular adaptation and vasculoprotection.

Vascular Dysfunction in Patients With Young β-Thalassemia

We aimed to study the endothelial dysfunction among children and adolescents with transfusion-dependent β-thalassemia using von Willebrand factor antigen (VWF:Ag) and flow cytometric analysis of circulating CD144+ endothelial microparticles (EMPs) and endothelial progenitor cells (CD34+VEGFR2+) and assess their relation to iron overload, erythropoietin and chelation therapy as well as echocardiographic parameters and carotid intima–media thickness. The VWF:Ag, EMPs, and CD34+VEGFR2+ cells were significantly higher among patients with β-thalassemia than controls ( P < .001). The type of chelation and patients’ compliance did not influence the results. No significant correlations were found between the studied vascular markers. Patients with evident heart disease had higher VWF: Ag, EMPs, and CD34+VEGFR2+ cells than those without. Carotid intima–media thickness was increased among patients but not correlated with vascular markers. We suggest that procoagulant EMPs and VWF: Ag are involved in cardiovascular complications in patients with young β-thalassemia. CD34+VEGFR2+ cells were further increased in response to tissue injury contributing to reendothelialization and neovascularization.

The CXCL12/CXCR4 chemokine ligand/receptor axis in cardiovascular disease

The chemokine receptor CXCR4 and its ligand CXCL12 play an important homeostatic function by mediating the homing of progenitor cells in the bone marrow and regulating their mobilization into peripheral tissues upon injury or stress. Although the CXCL12/CXCR4 interaction has long been regarded as a monogamous relation, the identification of the pro-inflammatory chemokine macrophage migration inhibitory factor (MIF) as an important second ligand for CXCR4, and of CXCR7 as an alternative receptor for CXCL12, has undermined this interpretation and has considerably complicated the understanding of CXCL12/CXCR4 signaling and associated biological functions. This review aims to provide insight into the current concept of the CXCL12/CXCR4 axis in myocardial infarction (MI) and its underlying pathologies such as atherosclerosis and injury-induced vascular restenosis. It will discuss main findings from in vitro studies, animal experiments and large-scale genome-wide association studies. The importance of the CXCL12/CXCR4 axis in progenitor cell homing and mobilization will be addressed, as will be the function of CXCR4 in different cell types involved in atherosclerosis. Finally, a potential translation of current knowledge on CXCR4 into future therapeutical application will be discussed.

Higher numbers of circulating endothelial progenitor cells in stroke patients with intracranial arterial stenosis

Background

Bone marrow-derived endothelial stem cells participate in vascular repairs. Numbers of circulating endothelial progenitor cells (cEPCs) are associated with atherosclerosis. Fibrinogen plays a key role in atherosclerosis. Objective was to assess if cEPC counts were associated with atherosclerotic intracranial artery stenosis (IAS).

Methods

Three hundred subjects (108 patients with stroke and IAS (IAS), 120 control patients with stroke without IAS (CP), and 72 healthy controls (HC)) were retrospectively analyzed. cEPCs were identified and counted by flow cytometry using CD34, CD133 and KDR. Plasma fibrinogen was measured by immunoturbidimetry. cEPC counts were compared between the three groups.

Results

cEPC numbers were significantly higher in IAS (0.059 ± 0.031%) than in CP (0.026 ± 0.012%) (P < 0.001) and HC (0.021 ± 0.011%) (P < 0.001), but without difference between CP and HC (P = 0.401). Multiple logistic regression analysis showed that cEPC levels (OR 3.31, 95%CI 1.26-8.87, P = 0.025; IAS vs. CP) were independent markers of IAS after adjustment for hypertension, diabetes and smoking. No significant correlation between cEPC counts and plasma fibrinogen levels was observed (P > 0.05).

Conclusion

cEPC numbers were associated with degrees of IAS. This measurement may be useful for non-invasive evaluation of atherosclerotic IAS.

Effect of therapeutic inhibition of TNF on circulating endothelial progenitor cells in patients with rheumatoid arthritis

Endothelial dysfunction has been detected in RA patients and seems to be reversed by control of inflammation. Low circulating endothelial progenitor cells (EPCs) have been described in many conditions associated with increased cardiovascular risk, including RA. The aim of this study was to investigate the effect of inhibition of TNF on EPCs in RA patients. Seventeen patients with moderate-severe RA and 12 sex and age-matched controls were evaluated. Endothelial biomarkers were tested at baseline and after 3 months. EPCs were identified from peripheral blood mononuclear cells by cytofluorimetry using anti-CD34 and anti-vascular endothelial growth factor-receptor 2. Asymmetric dimethylarginine (ADMA) was tested by ELISA and flow-mediated dilatation (FMD) by ultrasonography. Circulating EPCs were significantly lower in RA patients than in controls (P = 0.001). After 3 months EPCs increased significantly (P = 0.0006) while ADMA levels significantly decreased (P = 0.001). An inverse correlation between mean increase in EPCs number and mean decrease of DAS28 after treatment was observed (r = −0.56, P = 0.04). EPCs inversely correlated with ADMA (r = −0.41, P = 0.022). No improvement of FMD was detected. Short-term treatment with anti-TNF was able to increase circulating EPCs concurrently with a proportional decrease of disease activity suggesting that therapeutic intervention aimed at suppressing the inflammatory process might positively affect the endothelial function.

LOX-1, OxLDL, and atherosclerosis

Oxidized low-density lipoprotein (OxLDL) contributes to the atherosclerotic plaque formation and progression by several mechanisms, including the induction of endothelial cell activation and dysfunction, macrophage foam cell formation, and smooth muscle cell migration and proliferation. Vascular wall cells express on their surface several scavenger receptors that mediate the cellular effects of OxLDL. The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the main OxLDL receptor of endothelial cells, and it is expressed also in macrophages and smooth muscle cells. LOX-1 is almost undetectable under physiological conditions, but it is upregulated following the exposure to several proinflammatory and proatherogenic stimuli and can be detected in animal and human atherosclerotic lesions. The key contribution of LOX-1 to the atherogenic process has been confirmed in animal models; LOX-1 knockout mice exhibit reduced intima thickness and inflammation and increased expression of protective factors; on the contrary, LOX-1 overexpressing mice present an accelerated atherosclerotic lesion formation which is associated with increased inflammation. In humans, LOX-1 gene polymorphisms were associated with increased susceptibility to myocardial infarction. Inhibition of the LOX-1 receptor with chemicals or antisense nucleotides is currently being investigated and represents an emerging approach for controlling OxLDL-LOX-1 mediated proatherogenic effects.

Endothelial progenitor cells and erectile dysfunction: a brief review on diagnostic significance and summary of our experience

The article provides a brief review of the literature concerning the diagnostic use of endothelial progenitor cells in patients with erectile dysfunction. In particular, patients with arterial erectile dysfunction could benefit from the use of this diagnostic marker, which in clinical practice can be used together with more conventional methods such as the penile Doppler. It is very important to acquire diagnostic tools for the diagnosis of sub clinical form of endothelial dysfunction in these patients, in particular when the erectile dysfunction is associated with cardiovascular risk factors.

Influence of sildenafil and donepezil administration on the serum redox balance in experimentally induced lower limb critical ischemia

INTRODUCTION

Chronic lower limb ischemia (CLLI) leads to endothelial cell dysfunctions and endothelial lesions. The use of substances that release nitric oxide and activate endothelial nitric oxide synthase has proved to be useful in increasing angiogenesis and arteriogenesis under critical ischemia conditions.

OBJECTIVES

To investigate the therapeutic effect of Sildenafil and Donepezil with a vasodilating action in experimentally induced CLLI and on serum redox homeostasis.

MATERIAL AND METHOD

The research was performed in 3 groups of rats (n=10 animals/group) with experimentally induced CLLI: group I - control group; group II - animals treated postoperatively with a therapeutic dose of sildenafil, and group III - animals treated postoperatively with a therapeutic dose of donepezil. Oxidative stress (OS) indicators (malondialdehyde - MDA, protein carbonyls - PC), antioxidant (AO) defense indicators (reduced glutathione - GSH and oxidized glutathione - GSSH), and ceruloplasmin (CP) were determined on days 7, 14, 21 and 30. Statistical processing was performed using the Excel application (Microsoft Office 2007), with the StatsDirect v.2.7.2 software.

RESULTS

Changes in OS were evidenced in all groups on account of a decrease in MDA and PC. The greatest OS decrease in all groups was on day 30. AO defence changes were represented by decreased levels of GSH and GSSG in all groups, at the studied moments. Intracellular AO defense in the cytosol, nucleus and mitochondria was similar in all groups, (decreased GSH, GSSG and GSH/GSSG ratio). We found increased extracellular levels of GSH, GSSG, and CP and increased extracellular GSH/GSSG ratio at level compared to values on day 7.

CONCLUSIONS

1) The administration of sildenafil (group II) and donepezil (group III) has favorable effects on reducing OS in experimentally induced CLLI. 2) Sildenafil and Donepezil administration stimulates extracellular AO defense on account of CP. 3) Sildenafil and Donepezil administration influences intracellular redox homeostasis on account of the GSH/GSSG couple, the major redox buffer in the body.

Endothelial progenitor cell dysfunction in cardiovascular diseases: role of reactive oxygen species and inflammation

Endothelial progenitor cells (EPCs) move towards injured endothelium or inflamed tissues and incorporate into foci of neovascularisation, thereby improving blood flow and tissue repair. Patients with cardiovascular diseases have been shown to exhibit reduced EPC number and function. It has become increasingly apparent that these changes may be effected in response to enhanced oxidative stress, possibly as a result of systemic and localised inflammatory responses. The interplay between inflammation and oxidative stress affects the initiation, progression, and complications of cardiovascular diseases. Recent studies suggest that inflammation and oxidative stress modulate EPC bioactivity. Clinical medications with anti-inflammatory and antioxidant properties, such as statins, thiazolidinediones, angiotensin II receptor 1 blockers, and angiotensin-converting enzyme inhibitors, are currently administered to patients with cardiovascular diseases. These medications appear to exert beneficial effects on EPC biology. This review focuses on EPC biology and explores the links between oxidative stress, inflammation, and development of cardiovascular diseases.

Endothelial progenitor cells: the promise of cell-based therapies for acute lung injury

BACKGROUND

Endothelial progenitor cells (EPCs) are defined as a special type of stem cell that have been found to directly incorporate into injured vessels and that participate in angiogenesis and reconstruction by differentiation into endothelial cells. EPCs are widely used to therapeutically treat cardiovascular disease, limb ischemia and vascular repair. However, the role of EPCs in inflammatory diseases, especially in lung injury, is less studied.

OBJECTIVE

To investigate the application of EPCs to vascular repair, and the role of EPCs in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).

METHODS

A computer-based online search was performed in the PubMed database and Web of Science database for articles published, concerning EPCs, angiogenesis, ALI/ARDS and stem cell transplantation

CONCLUSION

EPCs have a therapeutic potential for vascular regeneration and may emerge as novel strategy for the diseases that are associated with ALI/ARDS.

MicroRNAs in Vascular Biology

Vascular inflammation is an important component of the pathophysiology of cardiovascular diseases, such as hypertension, atherosclerosis, and aneurysms. All vascular cells, including endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and infiltrating cells, such as macrophages, orchestrate a series of pathological events. Despite dramatic improvements in the treatment of atherosclerosis, the molecular basis of vascular inflammation is not well understood. In the last decade, microRNAs (miRNAs) have been revealed as novel regulators of vascular inflammation. Each miRNAs suppresses a set of genes, forming complex regulatory network. This paper provides an overview of current advances that have been made in revealing the roles of miRNAs during vascular inflammation. Recent studies show that miRNAs not only exist inside cells but also circulate in blood. These circulating miRNAs are useful biomarkers for diagnosis of cardiovascular diseases. Furthermore, recent studies demonstrate that circulating miRNAs are delivered into certain recipient cells and act as messengers. These studies suggest that miRNAs provide new therapeutic opportunities.