Vascular endothelial function and circulating endothelial progenitor cells in patients with cardiac syndrome X

Dysfunction of circulating endothelial progenitor cells in major depressive disorder

OBJECTIVES

Despite mounting evidence demonstrates circulating endothelial progenitor cells (cEPCs) quantitative changes in depression, no study has investigated cEPC functions in major depressive disorder (MDD). We investigated the role of cEPC adhesive and apoptotic functions in MDD.

METHODS

We recruited 68 patients with MDD and 56 healthy controls (HCs). The depression symptoms, anxiety, psychosomatic symptoms, subjective cognitive dysfunction, quality of life, and functional disability were evaluated using the Hamilton Depression Rating Scale and Montgomery-Åsberg Depression Rating Scale, Hamilton Anxiety Rating Scale, Depression and Somatic Symptoms Scale (DSSS), Perceived Deficits Questionnaire-Depression, 12-Item Short Form Health Survey (SF-12), and Sheehan Disability Scale (SDS), respectively. Working memory and executive function were assessed using a 2-back task and Wisconsin Card Sorting Test (WCST). Inflammatory marker (soluble interleukin-6 receptor, C-reactive protein, and tumor necrosis factor-α receptor-1), cEPC adhesive, and apoptotic levels were measured using in vitro assays.

RESULTS

The MDD patients showed significantly lower cEPC adhesive levels than the HCs, and this difference in adhesive function remained statistically significant even after adjusting for inflammatory marker levels. The cEPC adhesion levels were in inverse correlations with commission and omission errors in 2-back task, the percent perseverative response and percent perseverative errors in WCST, and the DSSS and SDS scores, but in positive correlations with SF-12 physical and mental component scores. cEPC apoptotic levels did not differ significantly between the groups.

CONCLUSION

The findings indicate that cEPC adhesive function is diminished in MDD and impacts various aspects of cognitive and psychosocial functions associated with the disorder.

Age-associated declined function of endothelial progenitor cells and its correlation with plasma IL-18 or IL-23 concentrations in patients with ST-segment elevation myocardial infarction

Background

ST-segment elevation myocardial infarction (STEMI) persists to be prevalent in the elderly with a dismal prognosis. The capacity of endothelial progenitor cells (EPCs) is reduced with aging. Nevertheless, the influence of aging on the functionality of EPCs in STEMI is not fully understood.

Method

This study enrolled 20 younger STEMI patients and 21 older STEMI patients. We assessed the Thrombolysis in Myocardial Infarction (TIMI) and Global Registry of Acute Coronary Events Risk (GRACE) scores in two groups. Then, we detected EPC migration, proliferation, adhesion, and plasma interleukin (IL)-18 and IL-23 concentrations in two groups. In addition, we analyzed the interconnection between age, EPC function, plasma IL-18 and IL-23 concentrations, and GRACE or TIMI scores in STEMI patients.

Result

GRACE and TIMI scores in older STEMI patients were higher than in younger STEMI patients, whereas EPC function declined. GRACE and TIMI scores were found to have an inverse relationship with the EPC function. In older STEMI patients, plasma concentrations of IL-18 and IL-23 increased. Plasma IL-18 and IL-23 concentrations were adversely connected to EPC capacity and positively related to GRACE and TIMI scores. Moreover, age was positively correlated with plasma IL-18 or IL-23 concentrations, as well as GRACE or TIMI scores. However, age was adversely correlated with EPC function.

Conclusion

In patients with STEMI, aging results in declined EPC function, which may be associated with inflammatory cytokines. The current investigation may offer new perception about mechanism and therapeutic targets of aging STEMI.

Circulating endothelial progenitor cell dysfunction in patients with bipolar disorder

Dysfunction in circulating endothelial progenitor cells (cEPCs) plays a crucial role in cardiovascular disorders (CVDs). Patients with bipolar disorder (BPD) are at increased risk of developing CVDs. This study examined the associations of the functional properties of cEPCs with BPD and its clinical and cognitive characteristics. We recruited 69 patients with BPD and 41 healthy controls (HCs). The levels of manic, depressive, anxiety, psychosomatic symptoms, subjective cognitive dysfunction, quality of life, and functional disability of the BPD group were evaluated using the Young Mania Rating Scale (YMRS), Clinical Global Impression for BPD (CGI-BP), Hamilton Depression Rating Scale, Montgomery-Åsberg Depression Rating Scale, Hamilton Anxiety Rating Scale, Depression and Somatic Symptoms Scale, Perceived Deficits Questionnaire-Depression, 12-Item Short-Form Health Survey, and Sheehan Disability Scale, respectively. Cognitive function was assessed using 2-back and Go/No-Go tasks. Through in vitro assays, the adhesion to fibronectin and the percentage of apoptosis of cEPCs were examined. Under correction for multiple comparisons, the adhesive function of cEPCs in BPD was significantly lower than that in the HCs (corrected P [Pcorr] = 0.027). The reduced adhesive function of cEPCs correlated significantly with increased scores in the YMRS (Pcorr = 0.0002) and the CGI-BP (Pcorr = 0.0009). A lower percentage of apoptotic cEPC cells was associated with greater commission errors in the 2-back (Pcorr = 0.028) and Go/No-Go tasks (Pcorr = 0.029). The cEPCs of the BPD group exhibited attenuated adhesive function. The altered adhesive and apoptotic functions of cEPCs are associated with manic symptom severity and response inhibition deficits in patients with BPD.

Aging-Related Endothelial Progenitor Cell Dysfunction and Its Association with IL-17 and IL-23 in HFmrEF Patients

Background

Aging is an independent risk factor for heart failure (HF), and endothelial progenitor cell (EPC) function decreases with aging. Here, we further investigated whether age has a detrimental effect on circulating EPC function in HF with mildly reduced ejection fraction (HFmrEF) and its relationship with systemic inflammation.

Methods

58 HFmrEF patients were recruited. The adhesive, migrative, and proliferative activities of circulating EPCs, MAGGIC scores, and plasma interleukin (IL)-17 and IL-23 levels of these patients were assessed.

Results

Older patients with HFmrEF had higher MAGGIC scores and lower circulating EPC adhesion, migration, and proliferation than younger patients. The similar tendency was observed in plasma IL-17 and IL-23 levels. The EPC functions were negatively associated with MAGGIC scores and plasma IL-17 or IL-23 levels.

Conclusions

In patients with HFmrEF, aging leads to attenuated circulating EPC function, which is correlated with disease severity and systemic inflammation. The present investigation provides some novel insights into the mechanism and intervention targets of HFmrEF.

Evaluation of Circulating Endothelial Progenitor Cells in Abdominal Aortic Aneurysms after Endovascular Aneurysm Repair

Background and Objectives

Circulating endothelial progenitor cells (EPCs) participate in vascular repair and predict cardiovascular outcomes. The aim of this study was to investigate the correlation between EPCs and abdominal aortic aneurysms (AAAs).

Methods and Results

Patients (age 67±9.41 years) suffering from AAAs (aortic diameters 58.09±11.24 mm) were prospectively enrolled in this study. All patients received endovascular aneurysm repair (EVAR). Blood samples were taken preoperatively and 14 days after surgery from patients with aortic aneurysms. Samples were also obtained from age-matched control subjects. Circulating EPCs were defined as those cells that were double positive for CD34 and CD309. Rat models of AAA formation were generated by the peri-adventitial elastase application of either saline solution (control; n=10), or porcine pancreatic elastase (PPE; n=14). The aortas were analyzed using an ultrasonic video system and immunohistochemistry. The levels of CD34^＋/CD309^＋ cells in the peripheral blood mononuclear cell populations were measured by flow cytometry. The baseline numbers of circulating EPCs (CD34^＋/CD309^＋) in the peripheral blood were significantly smaller in AAA patients compared with control subjects. The number of EPCs doubled by the 14th day after EVAR. A total of 78.57% of rats in the PPE group (11/14) formed AAAs (dilation ratio >150%). The numbers of EPCs from defined AAA rats were significantly decreased compared with the control group.

Conclusions

EPC levels may be useful for monitoring abdominal aorta aneurysms and rise after EVAR in patients with aortic aneurysms, and might contribute to the rapid endothelialization of vessels.

Increased circulating platelet and endothelial-derived microparticles in patients with cardiac syndrome X

BACKGROUND

Cardiac syndrome X (CSX) has been associated with endothelial dysfunction and inflammation. We conducted a case-control study to evaluate the association between plateletý and endothelial-derived microparticles (PMPs and EMPs), as specific quantitative plasma markers of endothelial dysfunction, and the presence of CSX.

METHODS

The present study was conducted on 40 CSX patients and 19 healthy individuals. C-reactive protein (CRP), and hematological and biochemical parameters were evaluated. The MP concentration in platelet-poor plasma (PPP) was quantitatively determined through flow cytometry using specific anti-human CD31, CD41a, CD62E, and CD144 antibodies.

RESULTS

The mean platelet volume (MPV) and positive CRP rate (≥ 3.8 mg/l) were higher in patients compared to controls (P = 0.020 and P = 0.010, respectively). The CD62E+, CD144+, and CD31+41− EMPs, as well as CD41+ and CD31+CD41+ PMPs showed significant increase in CSX patients compared to controls (P < 0.050). There were direct correlations between the mean percentage of detected EMPs and PMPs as well as between their expression intensity; however, a reverse correlation was seen between the percentage of MPs and CD144 and CD41. Moreover, the MP level was reversely associated with prothrombin time (PT) and partial thromboplastin time (PTT) values. Only CD31+CD41+ PMP was correlated with CRP.

CONCLUSION

It seems that EMPs and PMPs increase in CSX, which may contribute to various processes involved in the development of this syndrome.

Hypofunction of Circulating Endothelial Progenitor Cells and Aggravated Severity in Elderly Male Patients With Non-ST Segment Elevation Myocardial Infarction: Its Association With Systemic Inflammation

Background: Aging patients easily suffer from non-ST segment elevation myocardial infarction (NSTEMI). Our previous studies revealed declined function of endothelial progenitor cells (EPCs) in the elderly. However, the impact of aging on EPC function and severity in male NSTEMI patients and its possible mechanism is unclear until now.

Methods: We measured the circulating EPC function including migration, proliferation, and adhesion in aging or young male patients with NSTEMI. The GRACE and TIMI risk score were evaluated. Plasma levels of interleukin-6 (IL-6) and interleukin-17 (IL-17) were also detected in all patients.

Results: Compared with the young group, the old male patients with NSTEMI had higher GRACE score and TIMI score and decreased function of circulating EPCs. EPC function was negatively correlated with GRACE score and TIMI score. IL-6 and IL-17 level were higher in the old group than those in the young group. There was a significant negative correlation between EPC function and IL-6 or IL-17. Moreover, IL-6 and IL-17 positively correlated with GRACE and TIMI score. Age was positively related with GRACE or TIMI score and plasma level of IL-6 or IL-17, but inversely correlated with EPC function.

Conclusions: The current study firstly illustrates that the age-related decrement in EPC function is related to the severity of NSTEMI in male patients, which may be connected with systemic inflammation. These findings provide novel insights into the pathogenetic mechanism and intervention target of aging NSTEMI.

Upregulated anti-angiogenic miR-424-5p in type 1 diabetes (model of subclinical cardiovascular disease) correlates with endothelial progenitor cells, CXCR1/2 and other parameters of vascular health

Background

In spite of clinical progress, cardiovascular disease (CVD) remains the predominant cause of mortality worldwide. Overexpression studies in animals have proven miR-424-5p to have anti-angiogenic properties. As type 1 diabetes mellitus (T1DM) without CVD displays endothelial dysfunction and reduced circulating endothelial progenitor cells (cEPCs), it offers a model of subclinical CVD. Therefore, we explored miR-424-5p, cytokines and vascular health in T1DM.

Methods

Twenty-nine well-controlled T1DM patients with no CVD and 20-matched controls were studied. Cytokines IL8, TNF-α, IL7, VEGF-C, cEPCs/CD45^dimCD34⁺CD133⁺ cells and ex-vivo proangiogenic cells (PACs)/fibronectin adhesion assay (FAA) were measured. MiR-424-5p in plasma and peripheral blood mononuclear cells (PBMC) along with mRNAs in PBMC was evaluated.

Results

We found an elevation of IL7 (p = 0.008), IL8 (p = 0.003), TNF-α (p = 0.041), VEGF-C (p = 0.013), upregulation of mRNA CXCR1 (p = 0.009), CXCR2 (p < 0.001) and reduction of cEPCs (p < 0.001), PACs (p < 0.001) and FAA (p = 0.017) in T1DM. MiR-424-5p was upregulated in T1DM in PBMC (p < 0.001). MiR-424-5p was negatively correlated with cEPCs (p = 0.006), PACs (p = 0.005) and FAA (p < 0.001) and positively with HbA_1c (p < 0.001), IL7 (p = 0.008), IL8 (p = 0.017), VEGF-C (p = 0.007), CXCR1 (p = 0.02) and CXCR2 (p = 0.001). ROC curve analyses showed (1) miR-424-5p to be a biomarker for T1DM (p < 0.001) and (2) significant upregulation of miR-424-5p, defining subclinical CVD, occurred at HbA_1c of 46.5 mmol/mol (p = 0.002).

Conclusion

We validated animal research on anti-angiogenic properties of miR-424-5p in T1DM. MiR-424-5p may be a biomarker for onset of subclinical CVD at HbA_1c of 46.5 mmol/mol (pre-diabetes). Thus, miR-424-5p has potential use for CVD monitoring whilst anti-miR-424-5p-based therapies may be used to reduce CVD morbidity/mortality in T1DM.

Sevoflurane promotes the proliferation of HUVECs by activating VEGF signaling

The vascular endothelium plays an essential role in vascular disease and cardiovascular diseases. The effects and underlying mechanisms of sevoflurane on vascular endothelial growth factor (VEGF) in human endothelial cells have not been elucidated. The MTT colorimetric assay was used to determine HUVEC activity at different concentrations (1 and 3%, respectively) of sevoflurane for different time-points (12, 24 and 48 h, respectively). The regulation of sevoflurane on the mRNA levels of VEGFa, VEGFb, VEGFc and VEGFR1, 2, 3 was analyzed by real-time PCR. When VEGFR2 was inhibited by axitinib, VEGFR2 protein expression was determined by western blotting, and the cell viability was assessed by MTT analysis. The results revealed that sevoflurane increased cell viability in a dose- and time-dependent manner. Sevoflurane significantly upregulated VEGFA mRNA expression only. In addition, sevoflurane increased the expression of VEGFR2 at the mRNA and protein levels, whereas sevoflurane did not modulate the mRNA expression of VEGFR1 and VEGFR3. Furthermore, sevoflurane failed to increase the mRNA and protein expression of VEGFR2 when VEGFR2 was inhibited by axitinib, an inhibitor of VEGF receptors. In conclusion, sevoflurane may be a promising agent against endothelium dysfunction-caused vascular disease by activating the VEGF-A/VEGFR2 signaling pathway.

Trimethylamine N-Oxide, Circulating Endothelial Progenitor Cells, and Endothelial Function in Patients with Stable Angina

Trimethylamine N-oxide (TMAO) is a metabolite originated from bacterial metabolism of choline-rich foods. Evidence suggests an association between TMAO and atherosclerosis, but the relationship between TMAO and endothelial progenitor cells (EPCs) remains unclear. This study aimed to identify the relationship between TMAO concentrations, circulating EPCs, and endothelial function in patients with stable angina. Eighty-one stable angina subjects who underwent coronary angiography were enrolled. The circulating EPCs and flow-mediated vasodilation (FMD) were measured to evaluate endothelial function. Plasma TMAO and inflammatory markers, such as hsCRP and IL-1β, were determined. Furthermore, the effect of TMAO on EPCs was assessed in vitro. Patients with lower FMD had significantly decreased circulating EPCs, elevated TMAO, hsCRP, and IL-1β concentrations. Plasma TMAO levels were negatively correlated with circulating EPC numbers and the FMD, and positively correlated with hsCRP, IL-1β concentrations. In in vitro studies, incubation of TMAO in cultured EPCs promoted cellular inflammation, elevated oxidative stress, and suppressed EPC functions. Enhanced plasma TMAO levels were associated with reduced circulating EPCs numbers, endothelial dysfunction, and more adverse cardiovascular events. These findings provided evidence of TMAO’s toxicity on EPCs, and delivered new insight into the mechanism of TMAO-mediated atherosclerosis, which could be derived from TMAO-downregulated EPC functions.

Endothelial Progenitor Cells and Kidney Diseases

Endothelial progenitor cells (EPC) are bone marrow derived or tissue-resident cells that play major roles in the maintenance of vascular integrity and repair of endothelial damage. Although EPCs may be capable of directly engrafting and regenerating the endothelium, the most important effects of EPCs seem to be depended on paracrine effects. In recent studies, specific microvesicles and mRNAs have been found to mediate the pro-angiogenic and regenerative effects of EPCs on endothelium. EPC counts have important prognostic implications in cardiovascular diseases (CVD). Uremia and inflammation are associated with lower EPC counts which probably contribute to increased CVD risks in patients with chronic kidney disease. Beneficial effects of the EPC therapies have been shown in studies performed on different models of CVD and kidney diseases such as acute and chronic kidney diseases and glomerulonephritis. However, lack of a clear definition and specific marker of EPCs is the most important problem causing difficulties in interpretation of the results of the studies investigating EPCs.

Coronary Microcirculatory Dysfunction in Human Cardiomyopathies: A Pathologic and Pathophysiologic Review

Cardiomyopathies are a heterogeneous group of diseases of the myocardium. The term cardiomyopathy involves a wide range of pathogenic mechanisms that affect the structural and functional states of cardiomyocytes, extravascular tissues, and coronary vasculature, including both epicardial coronary arteries and the microcirculation. In the developed phase, cardiomyopathies present with various clinical symptoms: dyspnea, chest pain, palpitations, swelling of the extremities, arrhythmias, and sudden cardiac death. Due to the heterogeneity of cardiomyopathic patterns and symptoms, their diagnosis and therapies are great challenges. Despite extensive research, the relation between the structural and functional abnormalities of the myocardium and the coronary circulation are still not well understood in the various forms of cardiomyopathy. The main pathological characteristics of cardiomyopathies and the coronary microcirculation develop in a progressive manner due to (1) genetic-immunologic-systemic factors; (2) comorbidities with endothelial, myogenic, metabolic, and inflammatory changes; (3) aging-induced arteriosclerosis; and (4) myocardial fibrosis. The aim of this review is to summarize the most important common pathological features and/or adaptations of the coronary microcirculation in various types of cardiomyopathies and to integrate the present understanding of the underlying pathophysiological mechanisms responsible for the development of various types of cardiomyopathies. Although microvascular dysfunction is present and contributes to cardiac dysfunction and the potential outcome of disease, the current therapeutic approaches are not specific for the given types of cardiomyopathy.

Increased Circulating Visfatin Is Associated With Progression of Kidney Disease in Non-Diabetic Hypertensive Patients

BACKGROUD

Declining renal function is an independent risk factor for all-cause mortality in cardiovascular disease. Visfatin has been described as a marker of inflammation and endothelial dysfunction, but whether circulating visfatin levels are predictive to a subsequent decline in renal function remains unclear.

METHODS

In total, 200 nondiabetic, non-proteinuric hypertensive outpatients with initial serum creatinine (Scr) ≤1.5 mg/dl were enrolled. Plasma visfatin concentration and endothelial function estimated by brachial artery flow-mediated dilatation (FMD) were determined in the study subjects. The primary endpoints were the occurrence of renal events including doubling of Scr, 25% loss of glomerular filtration rate (GFR) from baseline values, and the occurrence of end-stage renal disease during follow-up.

RESULTS

The mean annual rate of GFR decline (ΔGFR/y) was -1.26±2.76 ml/min/1.73 m(2) per year during follow-up (8.6±2.5 years). At baseline, plasma visfatin was negatively correlated with estimated GFR. In longitudinal analysis, the ΔGFR/y was correlated with visfatin, baseline GFR, FMD, systolic blood pressure, and fasting blood glucose (FBG). Multivariate analysis indicated that increased visfatin (r = -0.331, P <0.001), baseline GFR (r = -0.234, P = 0.001), FMD (r = 0.163, P = 0.015), and FBG (r = -0.160, P = 0.015) are independent predictors of ΔeGFR/y. Cox regression model analysis showed that visfatin (hazard ratio (HR), 1.09; 95% confidence interval (CI), 1.05-1.13, P <0.001), FBG (HR, 1.01; 95% CI, 1.00-1.02, P = 0.020), and FMD (HR, 0.87; 95% CI, 0.76-1.00, P = 0.049) were independently associated with the risk of developing future renal events.

CONCLUSIONS

Increased circulating visfatin are associated with subsequent decline in renal function in nondiabetic hypertensive patients.

Oxidative stress activates endothelial innate immunity via sterol regulatory element binding protein 2 (SREBP2) transactivation of microRNA-92a

BACKGROUND

Oxidative stress activates endothelial innate immunity and disrupts endothelial functions, including endothelial nitric oxide synthase-derived nitric oxide bioavailability. Here, we postulated that oxidative stress induces sterol regulatory element-binding protein 2 (SREBP2) and microRNA-92a (miR-92a), which in turn activate endothelial innate immune response, leading to dysfunctional endothelium.

METHODS AND RESULTS

Using cultured endothelial cells challenged by diverse oxidative stresses, hypercholesterolemic zebrafish, and angiotensin II-infused or aged mice, we demonstrated that SREBP2 transactivation of microRNA-92a (miR-92a) is oxidative stress inducible. The SREBP2-induced miR-92a targets key molecules in endothelial homeostasis, including sirtuin 1, Krüppel-like factor 2, and Krüppel-like factor 4, leading to NOD-like receptor family pyrin domain-containing 3 inflammasome activation and endothelial nitric oxide synthase inhibition. In endothelial cell-specific SREBP2 transgenic mice, locked nucleic acid-modified antisense miR-92a attenuates inflammasome, improves vasodilation, and ameliorates angiotensin II-induced and aging-related atherogenesis. In patients with coronary artery disease, the level of circulating miR-92a is inversely correlated with endothelial cell-dependent, flow-mediated vasodilation and is positively correlated with serum level of interleukin-1β.

CONCLUSIONS

Our findings suggest that SREBP2-miR-92a-inflammasome exacerbates endothelial dysfunction during oxidative stress. Identification of this mechanism may help in the diagnosis or treatment of disorders associated with oxidative stress, innate immune activation, and endothelial dysfunction.

Effects of Cardiovascular Risk Factors on Endothelial Progenitor Cell

Atherosclerosis is a systemic inflammatory disease of arterial wall and initiated by endothelial damage. The integrity and functional activity of endothelial monolayer play an important role in atherogenesis. The extent of endothelial injury may represent a balance between the magnitude of injury and the capacity for repair. Traditional view suggested endothelium integrity is maintained by neighboring mature endothelial cells which migrate and proliferate to restore the injured endothelial cells. However, a series of clinical and basic studies prompted by the discovery of bone marrow-derived endothelial progenitor cells (EPCs) have demonstrated that the injured endothelial monolayer may be regenerated partly by circulating EPCs. These circulating EPCs are mobilized endogenously triggered by tissue ischemia or exogenously by cytokine stimulation. Clinical studies demonstrated that levels of circulating EPCs are associated with vascular endothelial function and cardiovascular risk factors, and help to identify patients at increased cardiovascular risk. Reduced levels of circulating EPCs independently predict atherosclerotic disease progression and development of cardiovascular events. Therefore, a better understanding of the relation between EPCs and atherosclerosis would provide additional insight into the pathogenesis of cardiovascular disease and create novel therapeutic strategies. Here, we will make a brief review to clarify the effects of cardiovascular risk factors on circulating EPCs.

KEY WORDS

Atherosclerosis; endothelial function; endothelial progenitor cell.

Coronary microvascular dysfunction in women: an overview of diagnostic strategies

Coronary microvascular dysfunction (CMD) also known as syndrome X, is characterized by typical anginal symptoms, evidence of myocardial ischemia on non-invasive testing and normal to minimal coronary disease on coronary angiography. It has a female preponderance and has been detected in up to 50% of women presenting with chest pain symptoms. Definitive diagnosis of CMD is critical as recent evidence suggests that women with this condition are at increased risk of cardiovascular events in the future. Invasive coronary reactivity testing on coronary angiography is considered to be the 'gold standard' for diagnosis of CMD. Non-invasive imaging techniques such as PET and cardiac magnetic resonance hold promise for detection of CMD in the future.

The relationship between endothelial progenitor cell populations and epicardial and microvascular coronary disease-a cellular, angiographic and physiologic study

BACKGROUND

Endothelial progenitor cells (EPCs) are implicated in protection against vascular disease. However, studies using angiography alone have reported conflicting results when relating EPCs to epicardial coronary artery disease (CAD) severity. Moreover, the relationship between different EPC types and the coronary microcirculation is unknown. We therefore investigated the relationship between EPC populations and coronary epicardial and microvascular disease.

METHODS

Thirty-three patients with a spectrum of isolated left anterior descending artery disease were studied. The coronary epicardial and microcirculation were physiologically interrogated by measurement of fractional flow reserve (FFR), index of microvascular resistance (IMR) and coronary flow reserve (CFR). Two distinct EPC populations (early EPC and late outgrowth endothelial cells [OECs]) were isolated from these patients and studied ex vivo.

RESULTS

There was a significant inverse relationship between circulating OEC levels and epicardial CAD severity, as assessed by FFR and angiography (r=0.371, p=0.04; r=-0.358, p=0.04; respectively). More severe epicardial CAD was associated with impaired OEC migration and tubulogenesis (r=0.59, p=0.005; r=0.589, p=0.004; respectively). Patients with significant epicardial CAD (FFR<0.75) had lower OEC levels and function compared to those without hemodynamically significant stenoses (p<0.05). In contrast, no such relationship was seen for early EPC number and function, nor was there a relationship between IMR and EPCs. There was a significant relationship between CFR and OEC function.

CONCLUSIONS

EPC populations differ in regards to their associations with CAD severity. The number and function of OECs, but not early EPCs, correlated significantly with epicardial CAD severity. There was no relationship between EPCs and severity of coronary microvascular disease.

Number and function of bone-marrow derived angiogenic cells and coronary flow reserve in women without obstructive coronary artery disease: a substudy of the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE)

BACKGROUND

In women with ischemia and no obstructive coronary artery disease, the Women's Ischemic Syndrome Evaluation (WISE) observed that microvascular coronary dysfunction (MCD) is the best independent predictor of adverse cardiovascular events. Since coronary microvascular tone is regulated in part by endothelium, we hypothesized that circulating endothelial cells (CEC), which reflect endothelial injury, and the number and function of bone-marrow derived angiogenic cells (BMDAC), which could help repair damaged endothelium, may serve as biomarkers for decreased coronary flow reserve (CFR) and MCD.

METHODS

We studied 32 women from the WISE cohort. CFR measurements in response to intracoronary adenosine were taken as an index of MCD. We enumerated BMDAC colonies and CEC in peripheral blood samples. BMDAC function was assessed by assay of migration of CD34+ cells toward SDF-1 and measurement of bioavailable nitric oxide (NO). These findings were compared with a healthy reference group and also entered into a multivariable model with CFR as the dependent variable.

RESULTS

Compared with a healthy reference group, women with MCD had lower numbers of BMDAC colonies [16 (0, 81) vs. 24 (14, 88); P = 0.01] and NO [936 (156, 1875) vs. 1168 (668, 1823); P = 0.02]. Multivariable regression analysis showed strong correlation of CFR to the combination of BMDAC colony count and CD34+ cell function (migration and NO) (R(2) = 0.45; P<0.05).

CONCLUSIONS

The BMDAC function and numbers of BMDAC colonies are decreased in symptomatic women with MCD and are independently associated with CFR. These circulating cells may provide mechanistic insights into MCD in women with ischemia.

Chest pain in patients with 'normal angiography': could it be cardiac?

Approximately 20% of patients undergoing diagnostic angiography for the evaluation of chest pain are found to have a normal coronary angiogram. Although this finding is generally associated with a low risk of cardiac events, approximately half will continue to experience chest pain over the next 12 months. Therefore, the finding of normal angiography warrants further evaluation of the potential causes for the presenting chest pain if we are to improve the disability suffered by these patients. In this review, the potential non-cardiac and cardiac causes for the chest pain in patients with normal angiography are briefly discussed with an in-depth focus on coronary vasomotor disorders including coronary artery spasm (variant angina) and microvascular disorders such as syndrome X, microvascular angina, the coronary slow flow phenomenon and microvascular spasm.

Increased circulating endothelial apoptotic microparticle to endothelial progenitor cell ratio is associated with subsequent decline in glomerular filtration rate in hypertensive patients

Background

Recent research indicates hypertensive patients with microalbuminuria have decreased endothelial progenitor cells (EPCs) and increased levels of endothelial apoptotic microparticles (EMP). However, whether these changes are related to a subsequent decline in glomerular filtration rate (GFR) remains unclear.

Methods and Results

We enrolled totally 100 hypertensive out-patients with eGFR ≥30 mL/min/1.73 m². The mean annual rate of GFR decline (△GFR/y) was −1.49±3.26 mL/min/1.73 m² per year during the follow-up period (34±6 months). Flow cytometry was used to assess circulating EPC (CD34⁺/KDR⁺) and EMP levels (CD31⁺/annexin V⁺) in peripheral blood. The △GFR/y was correlated with the EMP to EPC ratio (r = −0.465, p<0.001), microalbuminuria (r = −0.329, p = 0.001), and the Framingham risk score (r = −0.245, p = 0.013). When we divided the patients into 4 groups according to the EMP to EPC ratio, there was an association between the EMP to EPC ratio and the ΔGFR/y (mean ΔGFR/y: 0.08±3.04 vs. −0.50±2.84 vs. −1.25±2.49 vs. −4.42±2.82, p<0.001). Multivariate analysis indicated that increased EMP to EPC ratio is an independent predictor of ΔeGFR/y.

Conclusions

An increased circulating EMP to EPC ratio is associated with subsequent decline in GFR in hypertensive patients, which suggests endothelial damage with reduced vascular repair capacity may contribute to further deterioration of renal function in patients with hypertension.

Distinct angiogenesis roles and surface markers of early and late endothelial progenitor cells revealed by functional group analyses

Background

Endothelial progenitor cells (EPCs) play a fundamental role in post-natal vascular repair. Currently EPCs are defined as either early and late EPCs based on their biological properties and their time of appearance during in vitro culture. EPCs are rare and therefore optimizing isolation and culture is required before they can be applied as part of clinical therapies.

Results

We compared the gene profiles of early/late EPCs to their ancestors CD133+ or CD34+ stem cells and to matured endothelial cells pinpointing novel biomarkers and stemness genes. Late EPCs were enriched with proliferation and angiogenesis genes, participating in endothelial tubulogenesis and hence neovascularization. Early EPCs expressed abundant inflammatory cytokines and paracrine angiogenic factors, thereby promoting angiogenesis in a paracrine manner. Transcription factors involved in EPC stemness were pinpointed in early EPCs (MAF/MAFB) and in late EPCs (GATA6/IRF6).

Conclusions

The detailed mRNA expression profiles and functional module analysis for different EPCs will help the development of novel therapeutic modalities targeting cardiovascular disease, tumor angiogenesis and various ischemia-related diseases.

Differential expression of distinct surface markers in early endothelial progenitor cells and monocyte-derived macrophages

Bone marrow-derived endothelial progenitor cells (EPCs) play a fundamental role in postnatal angiogenesis. Currently, EPCs are defined as early and late EPCs based on their biological properties and their time of appearance during in vitro culture. Reports have shown that early EPCs share common properties and surface markers with adherent blood cells, especially CD14+ monocytes. Distinguishing early EPCs from circulating monocytes or monocyte-derived macrophages (MDMs) is therefore crucial to obtaining pure endothelial populations before they can be applied as part of clinical therapies. We compared the gene expression profiles of early EPCs, blood cells (including peripheral blood mononuclear cells, monocytes, and MDMs), and various endothelial lineage cells (including mature endothelial cells, late EPCs, and CD133+ stem cells). We found that early EPCs expressed an mRNA profile that showed the greatest similarity to MDMs than any other cell type tested. The functional significance of this molecular profiling data was explored by Gene Ontology database search. Novel plasma membrane genes that might potentially be novel isolation biomarkers were also pinpointed. Specifically, expression of CLEC5A was high in MDMs, whereas early EPCs expressed abundant SIGLEC8 and KCNE1. These detailed mRNA expression profiles and the identified functional modules will help to develop novel cell isolation approaches that will allow EPCs to be purified; these can then be used to target cardiovascular disease, tumor angiogenesis, and various ischemia-related diseases.

Reduced number and impaired function of circulating endothelial progenitor cells in patients with abdominal aortic aneurysm

AIM

Circulating endothelial progenitor cells (EPCs) are associated with coronary artery disease (CAD) and predict its outcome. Although the pathophysiology of abdominal aortic aneurysm (AAA) is different, it shares some risk factors with CAD. Therefore, the correlation between EPCs and AAA was investigated.

METHODS AND RESULTS

Seventy-eight subjects (age 77.2 ± 7.8 years) with suspected AAA were prospectively enrolled. Cut-off values (men, 3.5-5.5 cm; women, 3-5 cm) were used to define normal aorta, small AAA, and large AAA on thoraco-abdominal computer tomography. Endothelial function was measured by flow-mediated vasodilation (FMD). Flow cytometry and colony-forming units (CFUs) were used to evaluate circulating EPC numbers. Circulating EPCs were defined as mononuclear cells with low CD45 staining and double-positive staining for KDR, CD34, or CD133. Late out-growth EPCs were cultured from six patients with large AAAs and six age- and sex-matched controls to evaluate proliferation, adhesion, migration, tube formation, and senescence. FMD was significantly lower with large (5.26% ± 3.11%) and small AAAs (6.31% ± 3.66%) than in controls (8.88% ± 4.83%, P=0.008). Both CFUs (normal 38.39 ± 12.99, small AAA 21.22 ± 7.14, large AAA 6.98 ± 1.97; P=0.026) and circulating EPCs (CD34(+)/KDR(+) and CD133(+)/KDR(+)) were significantly fewer in AAA patients than in controls. On multivariate analysis, CFUs and circulating EPCs (CD34(+)/KDR(+)) were independently, inversely correlated to AAA diameter. Proliferation, adhesion, migration, tube formation, and senescence of late EPCs were significantly impaired in AAA patients.

CONCLUSION

The number and function of EPCs were impaired in AAA patients, suggesting their potential role in AAA.

Genetic module and miRNome trait analyses reflect the distinct biological features of endothelial progenitor cells from different anatomic locations

Background

Endothelial progenitor cells (EPCs) play a fundamental role in post-natal vascular repair, yet EPCs from different anatomic locations possess unique biological properties. The underlying mechanisms are unclear.

Results

EPCs from CB expressed abundant genes involved in cell cycle, hypoxia signalling and blood vessel development, correlating with the phenotypes that CB-EPCs proliferated more rapidly, migrated faster, and formed tubule structure more efficiently. smRNA-seq further deciphered miRNome patterns in EPCs isolated from CB or PB: 54 miRNAs were enriched in CB-EPCs, while another 50 in PB-EPCs. Specifically, CB-EPCs expressed more angiogenic miRNAs such as miR-31, while PB-EPCs possessed more tumor suppressive miRNAs including miR-10a. Knocking down miR-31 levels in CB-EPCs suppressed cell migration and microtubule formation, while overexpressing miR-31 in PB-EPCs helped to recapitulate some of CB-EPC functions.

Conclusions

Our results show the foundation for a more detailed understanding of EPCs from different anatomic sources. Stimulating the expression of angiogenic microRNAs or genes in EPCs of low activity (such as those from patients with cardiovascular diseases) might allow the development of novel therapeutic strategies.

Cardiac syndrome X and microvascular coronary dysfunction

Women with cardiac chest pain indicated by signs and symptoms of myocardial ischemia in the absence of obstructive CAD are often labelled as cardiac syndrome X (CSX). A subset of patients with CSX may have symptoms of ischemia due to microvascular dysfunction. Angina due to microvascular coronary dysfunction (MCD) is an etiologic mechanism in women with vascular dysfunction. New data provide improve understanding of coronary vascular dysfunction and resultant myocardial ischemia that characterize MCD among patients with cardiac syndrome X. MCD has an adverse prognosis and health care cost expenditure comparable to obstructive CAD. The high prevalence of this condition, particularly in women, adverse prognosis and substantial health care costs, coupled with a lack of evidence regarding treatment strategies, places MCD as a research priority area.

Critical reevaluation of endothelial progenitor cell phenotypes for therapeutic and diagnostic use

Diverse subsets of endothelial progenitor cells (EPCs) are used for the treatment of ischemic diseases in clinical trials, and circulating EPCs levels are considered as biomarkers for coronary and peripheral artery disease. However, despite significant steps forward in defining their potential for both therapeutic and diagnostic purposes, further progress has been mired by unresolved questions around the definition and the mechanism of action of EPCs. Diverse culturing methods and detection of various combinations of different surface antigens were used to enrich and identify EPCs. These attempts were particularly challenged by the close relationship and overlapping markers of the endothelial and hematopoietic lineages. This article will critically review the most commonly used protocols to define EPCs by culture assays or by fluorescence-activated cell sorter in the context of their therapeutic or diagnostic use. We also delineate new research avenues to move forward our knowledge on EPC biology.

Decreased circulating endothelial progenitor cell levels and function in patients with nonalcoholic fatty liver disease

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is associated with advanced atherosclerosis and a higher risk of cardiovascular disease. Increasing evidence suggests that injured endothelial monolayer is regenerated by circulating bone marrow derived-endothelial progenitor cells (EPCs), and levels of circulating EPCs reflect vascular repair capacity. However, the relation between NAFLD and EPC remains unclear. Here, we tested the hypothesis that patients with nonalcoholic fatty liver disease (NAFLD) might have decreased endothelial progenitor cell (EPC) levels and attenuated EPC function.

METHODS AND RESULTS

A total of 312 consecutive patients undergoing elective coronary angiography because of suspected coronary artery disease were screened and received examinations of abdominal ultrasonography between July 2009 and November 2010. Finally, 34 patients with an ultrasonographic diagnosis of NAFLD, and 68 age- and sex-matched controls without NAFLD were enrolled. Flow cytometry with quantification of EPC markers (defined as CD34(+), CD34(+)KDR(+), and CD34(+)KDR(+)CD133(+)) in peripheral blood samples was used to assess circulating EPC numbers. The adhesive function, and migration, and tube formation capacities of EPCs were also determined in NAFLD patients and controls. Patients with NAFLD had a significantly higher incidence of metabolic syndrome, previous myocardial infarction, hyperuricemia, and higher waist circumference, body mass index, fasting glucose and triglyceride levels. In addition, patients with NAFLD had significantly decreased circulating EPC levels (all P<0.05), attenuated EPC functions, and enhanced systemic inflammation compared to controls. Multivariate logistic regression analysis showed that circulating EPC level (CD34(+)KDR(+) [cells/10(5) events]) was an independent reverse predictor of NAFLD (Odds ratio: 0.78; 95% confidence interval: 0.69-0.89, P<0.001).

CONCLUSIONS

NAFLD patients have decreased circulating EPC numbers and functions than those without NAFLD, which may be one of the mechanisms to explain atherosclerotic disease progression and enhanced cardiovascular risk in patients with NAFLD.

Decreased circulating endothelial progenitor cell levels and function in essential hypertensive patients with electrocardiographic left ventricular hypertrophy

The aim of this study was to explore the role of circulating endothelial progenitor cells (EPCs) and endothelial apoptotic microparticles in hypertensive patients with and without electrocardiographic left ventricular hypertrophy (LVH). Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC level by quantification of circulating EPC markers (defined as CD34(+)CD133(+), CD34(+)KDR(+)) and endothelial apoptotic microparticles (defined as CD31(+)/annexin V(+)) in peripheral blood samples. The LVH was defined by ECG with the Cornell voltage criteria. In total, 128 hypertensive patients (83 men and 45 women, aged 59±14 years) were enrolled in this study, in which 107 patients (84%) showed no electrocardiographic evidence of LVH, and 21 patients (16%) fulfilled the LVH criteria by ECG. There were no significant differences in basic characteristics between the two groups, but hypertensive patients with LVH had a higher urine albumin excretion rate than those without LVH (P=0.027). Furthermore, hypertensive patients with LVH were shown to have decreased circulating EPC numbers (all P<0.05) and adhesive function compared with those without LVH (LVH vs. no LVH: 14±6 vs. 30±6 cells per high-power field, P<0.001). Increased numbers of endothelial apoptotic microparticles were noted in hypertensive patients with LVH (4.2±4.9 vs. 2.4±3.4%, P=0.115), although the difference was not significant. This study showed that essential hypertensive patients with electrocardiographic LVH evidence have decreased circulating EPC numbers and adhesive function compared with those without LVH. These findings may explain the pathogenetic processes that link hypertensive LVH and endothelial injury in cardiovascular disease.

Contemporary treatment of Western and Chinese medicine for cardiac syndrome X

Clinical reports on cardiac syndrome X (CSX) have been increasing in recent years. In general, CSX does not increase the cardiovascular mortality, but it can affect the patient's quality of life (QOL) and increase the incidence rates of cardiovascular and cerebrovascular events. Although a variety of drugs and therapies have been utilized in the clinical treatment, the management of CSX still represents a major challenge due to its unclear pathogenesis. It is necessary to explore more effective treatment programs. Many attempts have been made on trials of the Chinese medicine (CM) treatment for CSX and proved that CM has a certain advantage in efficacy to improve clinical symptoms and QOL. CM may provide a new approach for the effective treatment of CSX.

The endotheliome: a new concept in vascular biology

As the importance of the endothelium is becoming increasingly recognised, additional tools are needed to assess its functions. Separate studies have looked at different aspects of vascular biology primarily focusing on the central role of the endothelium, i.e. secretion/release of molecules in the plasma, physiological action on other cells, and the presence of endothelial cells themselves in the circulation. Targeting and protecting the endothelium is a promising therapeutic strategy for modifying a number of disease processes but 'ideal' methods to monitor this treatment, like many other tools for assessing endothelial activity, remain elusive. We suggest that a broader view of the endothelium is important, and with it the concept of the assessment of overall vascular function, which fuses different aspects of endothelial activity into a unifying concept. In the present document we review the current understanding of endothelial biology and the methods of its assessment, and hypothesise that a more multifactorial approach to the endothelium will be a crucial determinant of outcomes and treatment strategies for different diseases. This we describe as the 'endotheliome'.

Increased circulating CD31+/annexin V+ apoptotic microparticles and decreased circulating endothelial progenitor cell levels in hypertensive patients with microalbuminuria

OBJECTIVE

Microalbuminuria is associated with an increased risk for all-cause and cardiovascular mortality, but the pathophysiologic mechanism underlying the association between urinary albumin excretion and cardiovascular disease remains unclear. Here, we tested the hypothesis that enhanced endothelial apoptotic microparticles and decreased endothelial progenitor cell (EPC) levels might contribute to the pathophysiology of microalbuminuria or macroalbuminuria in cardiovascular disease.

METHODS

Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC levels by quantification of circulating CD31/annexin V apoptotic microparticles and EPC markers (defined as KDRCD133, CD34CD133, CD34KDR) in peripheral blood.

RESULTS

In total, 125 patients with hypertension were enrolled in the study, of whom 80 patients (64%) were with normoalbuminuria (albumin excretion rate of <20 microg/min, overnight urine samples), 35 patients (28%) with microalbuminuria (an albumin excretion rate of 20-200 microg/min), and 10 patients (8%) with macroalbuminuria (an albumin excretion rate >200 microg/min). Compared to hypertensive patients with normoalbuminuria, patients with microalbuminuria or macroalbuminuria had significantly more diabetes (P = 0.005), higher systolic blood pressure (P = 0.018), and elevated serum creatinine levels (P < 0.001). Among the three groups, patients with microalbuminuria or macroalbuminuria had significantly increased CD31/annexin V apoptotic microparticles (1.8 +/- 2.2 versus 3.0 +/- 4.3 versus 5.2 +/- 6.2%, P = 0.044) and decreased circulating EPC numbers (P < 0.05). By multivariate analysis, CD31/annexin V apoptotic microparticle level was an independent predictor of urinary albumin excretion rate in hypertensive patients (P < 0.001). Microparticles isolated from hypertensive patients with microalbuminuria or macroalbuminuria attenuated EPC proliferation, migration, and increased H2O2 production, cellular senescence and apoptosis in comparison with those from hypertensive patients with normoalbuminuria.

CONCLUSION

These findings suggest that hypertensive patients with microalbuminuria or macroalbuminuria have increased endothelial apoptotic microparticles and decreased circulating EPC levels, which may contribute to atherosclerotic disease progression and enhanced cardiovascular risk in hypertensive patients with nephropathy.

Bone marrow and circulating stem/progenitor cells for regenerative cardiovascular therapy

Cardiovascular disease is the leading cause of death and disability in the Western world. In addition to the advancement of current therapeutic approaches to reduce the associated morbidity and mortality, regenerative medicine and cell-based therapy have been areas of continuous investigation. Circulating and bone-marrow-derived stem or endothelial progenitor cells are an attractive source for regenerative therapy in the cardiovascular field. In this review, we highlight the advantages and limitations of this approach with a focus on key observations from animal studies and clinical trials.

Smoking decreases the level of circulating CD34+ progenitor cells in young healthy women--a pilot study

BACKGROUND

Decreased levels of circulating bone marrow-derived progenitor cells have been associated with risk factors and cardiovascular diseases. Smoking is the most important modifiable risk factor for atherosclerosis in young women. The aim of this pilot study was to assess in healthy premenopausal women without other risk factors for cardiovascular disease the influence of nicotine abuse on the number of circulating progenitor cells in relation to endothelial function.

METHODS

The number of endothelial progenitor cells, measured as colony-forming units in a cell-culture assay (EPC-CFU) and the number of circulating CD34 + and CD34 + /CD133 + cells, measured by flow cytometry, was estimated in 32 women at the menstrual phase of the menstrual cycle. In addition, flow-mediated dilation (FMD) was assessed as a marker for vascular function. In a subgroup of these women (n = 20), progenitor cells were also investigated at the mid-follicular and luteal phases of the menstrual cycle.

RESULTS

Compared to non-smokers, the abundance of circulating CD34 + cells was significantly lower in smoking women in the menstrual, mid-luteal, and mid-follicular phases of the menstrual cycle. The number of CD34 + progenitor cells was revealed to have significant positive correlation with FMD in young healthy women, whereas CD34 + /CD133 + progenitor cells and EPC-CFU showed no significant correlation.

CONCLUSION

The number of CD34 + progenitor cells positively correlates with FMD in young healthy women and is decreased by smoking.

Definitions and incidence of cardiac syndrome X: review and analysis of clinical data

There is no consensus regarding the definition of cardiac syndrome X (CSX). We systematically reviewed recent literature using a standardized search strategy. We included 57 articles. A total of 47 studies mentioned a male/female distribution. A meta-analysis yielded a pooled proportion of females of 0.56 (n = 1,934 patients, with 95% confidence interval: 0.54-0.59). As much as 9 inclusion criteria and 43 exclusion criteria were found in the 57 articles. Applying these criteria to a population with normal coronary angiograms and treated in 1 year at a general hospital, the attributable CSX incidence varied between 3 and 11%. The many inclusion and exclusion criteria result in a wide range of definitions of CSX and these have large effects on the incidence. This shows the need for a generally accepted definition of CSX.

Intake of Red Wine Increases the Number and Functional Capacity of Circulating Endothelial Progenitor Cells by Enhancing Nitric Oxide Bioavailability

Objective— Red wine (RW) consumption has been associated with a reduction of cardiovascular events, but limited data are available on potential mediating mechanisms. This study tested the hypothesis that intake of RW may promote the circulating endothelial progenitor cell (EPC) level and function through enhancement of nitric oxide bioavailability.

Methods and Results— Eighty healthy, young subjects were randomized and assigned to consume water (100 mL), RW (100 mL), beer (250 mL), or vodka (30 mL) daily for 3 weeks. Flow cytometry was used to quantify circulating EPC numbers, and in vitro assays were used to evaluate EPC functions. After RW ingestion, endothelial function determined by flow-mediated vasodilation was significantly enhanced; however, it remained unchanged after water, beer, or vodka intake. There were significantly increased numbers of circulating EPC (defined as KDR + CD133 + , CD34 + CD133 + , CD34 + KDR + ) and EPC colony-forming units only in the RW group (all P <0.05). Only RW ingestion significantly enhanced plasma levels of nitric oxide and decreased asymmetrical dimethylarginine (both P <0.01). Incubation of EPC with RW (but not beer or ethanol) and resveratrol in vitro attenuated tumor necrosis factor-α–induced EPC senescence and improved tumor necrosis factor-α–suppressed EPC functions and tube formation. Incubation with nitric oxide donor sodium nitroprusside significantly ameliorated the inhibition of tumor necrosis factor-α on EPC proliferation, but incubation with endothelial nitric oxide synthase inhibitor l -NAME and PI3K inhibitor markedly attenuated the effect of RW on EPC proliferation.

Conclusion— The intake of RW significantly enhanced circulating EPC levels and improved EPC functions by modifying nitric oxide bioavailability. These findings may help explain the beneficial effects of RW on the cardiovascular system. This study demonstrated that a moderate intake of RW can enhance circulating levels of EPC in healthy subjects by increasing nitric oxide availability. Direct incubation of EPC with RW and resveratrol can modify the functions of EPC, including attenuation of senescence and promotion of EPC adhesion, migration, and tube formation. These data suggest that RW ingestion may alter the biology of EPC, and these alterations may contribute to its unique cardiovascular-protective effect.

Endothelial precursors in vascular repair

The endothelium is an essential component of the cardiovascular system, playing a vital role in blood vessel formation, vascular homeostasis, permeability and the regulation of inflammation. The integrity of the endothelial monolayer is also critical in the prevention of atherogenesis and as such, restoration of the monolayer is essential following damage or cell death. Over the past decade, data has suggested that progenitor cells from different origins within the body are released into the circulation and contribute to re-endothelialisation. These cells, termed endothelial progenitor cells (EPCs), also gave rise to the theory of new vessel formation within adults (vasculogenesis) without proliferation and migration of mature endothelial cells (angiogenesis). As such, intense research has been carried out identifying how these cells may be mobilised and contribute to vascular repair, either encouraging vasculogenesis into regions of ischemia or the re-endothelialisation of vessels with a dysfunctional endothelium. However, classification and isolation procedures have been a major problem in this area of research and beneficial use for therapeutic application has been controversial. In the present review we focus on the role of EPCs in vascular repair. We also provide an update on EPC classification and discuss autologous stem cell-derived endothelial cell (EC) as a functional source for therapy.

Matrix metalloproteinase-9 is essential for ischemia-induced neovascularization by modulating bone marrow-derived endothelial progenitor cells

OBJECTIVE

Both matrix metalloproteinases (MMPs) and endothelial progenitor cells (EPCs) have been implicated in the process of neovascularization. Here we show that the impaired neovascularization in mice lacking MMP-9 is related to a defect in EPC functions in vasculogenesis.

METHODS AND RESULTS

Hindlimb ischemia surgery was conducted in MMP-9(-/-) mice and wild-type (MMP-9(+/+)) mice. Blood flow recovery was markedly impaired in MMP-9(-/-) mice when compared with that in wild-type mice as determined by laser Doppler imaging. Flow cytometry demonstrated that the number of EPC-like cells (Sca-1(+)/Flk-1(+)) in peripheral blood increased in wild-type mice after hindlimb ischemia surgery and exogenous vascular endothelial growth factor stimulation, but not in MMP-9(-/-) mice. Plasma levels and bone marrow concentrations of soluble Kit-ligand (sKitL) were significantly elevated in wild-type mice in response to tissue ischemia, but not in MMP-9(-/-) mice. C-kit positive bone marrow cells of MMP-9(-/-) mice have attenuated adhesion and migration than those isolated from wild-type mice. In in vitro studies, incubation with selective MMP-9 inhibitor suppressed the colony formation, migration, and tube formation capacities of EPC. Transplantation of bone marrow cells from wild-type mice restored collateral flow formation in MMP-9(-/-) mice.

CONCLUSIONS

These findings suggest that MMP-9 deficiency impairs ischemia-induced neovascularization, and these effects may occur through a reduction in releasing the stem cell-active cytokine, and EPC mobilization, migration, and vasculogenesis functions.

From bone marrow to the arterial wall: the ongoing tale of endothelial progenitor cells

Several physiological and pathophysiological stimuli or drugs modulate endothelial progenitor cell (EPC) mobilization. Moreover, levels of circulating EPCs predict cardiovascular risk and left ventricular remodelling after myocardial infarction. Nevertheless, our understanding in this field is complicated by lack of an unequivocal definition of EPCs, thus limiting their clinical applications. This review summarizes current knowledge and uncertainties on EPC characterization and mobilization in the attempt to define their role in the management of cardiovascular diseases.

Serum ADMA concentration-- an independent factor determining FMD impairment in cardiac syndrome X

Mechanisms of decreased endogenous vascular reactivity in individuals with cardiac syndrome X (CSX) are not fully understood.

AIM

To evaluate the following serum markers: total nitric oxide (NO), asymmetric dimethylarginine (ADMA), platelet-derived growth factor (PDGF), and to establish their relation to ultrasound indexes of endothelial function and structural remodeling in CSX patients.

METHOD

The study group consisted of 43 CSX patients (mean age: 56.3 +/- 9 years), while the control group included 21 healthy subjects (mean age: 54.86 +/- 6.9 years). The high-resolution ultrasound was performed to measure: flow-mediated vasodilatation (FMD), nitroglycerine-mediated vasodilatation (NMD) and intima-media thickness (IMT) of carotid arteries.

RESULTS

In CSX patients, significantly lower FMD (9.06 +/- 3.2%) and significantly higher IMT (0.667 +/- 0.14 mm) values were observed compared to healthy individuals (17.42 +/- 8.4%, 0.571 +/- 0.2 mm; P < 0.05). Mean total NO serum concentration was significantly higher in the CSX group (48.2 +/- 18.2 micromol/L) as compared to controls (32.1 +/- 1.4 micromol/L; P < 0.0001). There were no differences in serum ADMA and PDGF levels. In CSX patients, FMD values correlated with NO (r = 0.323; P = 0.039) and ADMA (r = -0.387; P = 0.012) serum levels; however, there were no significant correlations between NO and ADMA concentrations.

CONCLUSION

Serum ADMA concentration is the only independent factor determining FMD impairment.

Review: Hypercholesterolemia-associated endothelial progenitor cell dysfunction

Hypercholesterolemia has been associated with increased cardiovascular risk by contributing to mechanical endothelial injury and dysfunction. There is evidence that chronic exposure to increased plasma cholesterol levels might also impair the repair of lipoprotein-mediated endothelial injury, possibly by reducing the availability and function of circulating endothelial progenitors. This review summarizes current knowledge about the mechanisms of lipoprotein-mediated endothelial injury and endothelial progenitor cell assisted vascular repair; the influence of hypercholesterolemia on endothelial progenitor cell dysfunction will be also addressed.

Enhanced external counterpulsation is an effective treatment for Syndrome X

Enhanced external counterpulsation (EECP) was used to treat 30 patients with refractory angina due to cardiac Syndrome X, with an initial improvement in CCS angina class (3.57 to 1.43; p<0.001) and regional ischemia in all treated patients. At a mean of 11.9 months follow-up, 87% of patients had sustained improvement in angina and were without MACE. EECP, by improving endothelial function, may be an effective and durable treatment for this often difficult to treat problem.

Circulating CD34+ cell subsets in patients with coronary endothelial dysfunction

BACKGROUND

Endothelial dysfunction is an early manifestation of atherosclerotic disease. Circulating cells that express CD34, including endothelial and hematopoietic progenitor cells, might play a part in the development and progression of atherosclerosis. The aim of this study was to evaluate the association between coronary endothelial dysfunction and concentrations of circulating CD34+ cell subsets.

METHODS

Intracoronary acetylcholine challenge was used to test for coronary endothelial dysfunction in 57 consecutive patients scheduled to undergo diagnostic coronary angiography and with no signs of substantial obstructive lesions. Mononuclear cells were extracted from whole blood samples taken from all patients, analyzed by flow cytometry for CD14, CD34, CD133, CD45, and vascular endothelial growth factor receptor 2 (VEGFR2), and cultured for functional analysis.

RESULTS

Compared with patients with normal coronary endothelial function, in those with coronary endothelial dysfunction, the number of circulating CD34+/CD45(dim)/VEGFR2- cells, CD34+/CD45(dim)/CD133+/VEGFR2- cells and colony-forming units were reduced. Concentrations of CD34+/CD45-/VEGFR2+ cells did not differ between groups.

CONCLUSIONS

Regulation of CD34+ cell subsets seems to differ between patients with coronary endothelial dysfunction and those with normal coronary endothelial function. Changes in specific circulating progenitor cell subsets might, therefore, be an early manifestation of atherosclerosis.