scholarly journals Dysfunctional Endothelial Progenitor Cells in Metabolic Syndrome

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Sridevi Devaraj ◽  
Ishwarlal Jialal

The metabolic syndrome (MetS) is highly prevalent and confers an increased risk of diabetes and cardiovascular disease. A key early event in atherosclerosis is endothelial dysfunction. Numerous groups have reported endothelial dysfunction in MetS. However, the measurement of endothelial function is far from optimum. There has been much interest recently in a subtype of progenitor cells, termed endothelial progenitor cells (EPCs), that can circulate, proliferate, and dfferentiate into mature endothelial cells. EPCs can be characterized by the assessment of surface markers, CD34 and vascular endothelial growth factor receptor-2, VEGFR-2 (KDR). The CD34+KDR+phenotype has been demonstrated to be an independent predictor of cardiovascular outcomes. MetS patients without diabetes or cardiovascular diseases have decreased EPC number and functionality as evidenced by decreased numbers of colony forming units, decreased adhesion and migration, and decreased tubule formation. Strategies that have been shown to upregulate and enhance EPC number and functionality include statins, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, and peroxisome-proliferator-activating-receptor gamma agonists. Mechanisms by which they affect EPC number and functionality need to be studied. Thus, EPC number and/or functionality could emerge as novel cellular biomarkers of endothelial dysfunction and cardiovascular disease risk in MetS.

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Paulo F Leite ◽  
Claudia R Andrade ◽  
Santa Poppe ◽  
Luiz A Cesar ◽  
Silmara Coimbra ◽  
...  

Underlying mechanisms of endothelial dysfunction in obesity are not fully understood. Circulating Endothelial Progenitor Cells (EPCs) are known to promote endothelial repair. Our aim was to assess the number/function of EPCs in morbid obese individuals and its correlation with endothelial function and inflammatory markers. EPCs were isolated from 33 morbid obese patients (age 47±1.8 y; men=34%; BMI=49±2.1 kg/m 2 , metabolic syndrome=84%) and 20 lean controls. Peripheral blood EPC number was significantly reduced in obese patients both with flow cytometry (KDR + /CD34 + ; 0.041±0.04 vs 0.074±0.05 %events, p<0.001) and fluorescence analysis after short-term culture (49±4 vs 28±2 cells/field, p<0.001). The plasma number of primitive CD 133 + cells, and concentrations of VEGF (Elisa) and nitrogen oxides (which potentially recruit EPCs), were similar to control, suggesting that reduction of EPCs occurs distally to early cell differentiation. Importantly, C-Reactive Protein (CRP), robustly increased in obese patients (0.15±0.04 vs 1.3±0.3; p=0.003), was a strong predictor of reduced EPC number at multivariate analysis (r=0.623; p < 0.001). Likewise, the migratory response of EPCs to VEGF in vitro was significantly impaired in obese vs controls, despite similar VEGF receptor numbers. Multivariate analysis suggested potential roles of metabolic syndrome and leptin in such effect. Endothelial function at flow-mediated brachial artery reactivity was markedly reduced (by 60%) in obese patients, and had a significant inverse correlation with EPC number (r= 0.678; p< 0.001). Carotid intimal thickness was also increased in obese patients (0.68±0.02 vs 0.58±0.08; p=0.001). On the other hand, the number of circulating endothelial cells (CD31 + /CD106 + ) was similar in both groups, suggesting that apoptosis was not enhanced in the obese. These results suggest for the first time that reduced number and migratory capacity of EPCs correlate with endothelial dysfunction or increased CRP and may be a key underlying mechanism of vascular complications and atherosclerosis in obesity.


2010 ◽  
Vol 120 (7) ◽  
pp. 263-283 ◽  
Author(s):  
Shaundeep Sen ◽  
Stephen P. McDonald ◽  
P. Toby H. Coates ◽  
Claudine S. Bonder

Bone-marrow-derived EPCs (endothelial progenitor cells) play an integral role in the regulation and protection of the endothelium, as well as new vessel formation. Peripheral circulating EPC number and function are robust biomarkers of vascular risk for a multitude of diseases, particularly CVD (cardiovascular disease). Importantly, using EPCs as a biomarker is independent of both traditional and non-traditional risk factors (e.g. hypertension, hypercholesterolaemia and C-reactive protein), with infused ex vivo-expanded EPCs showing potential for improved endothelial function and either reducing the risk of events or enhancing recovery from ischaemia. However, as the number of existing cardiovascular risk factors is variable between patients, simple EPC counts do not adequately describe vascular disease risk in all clinical conditions and, as such, the risk of CVD remains. It is likely that this limitation is attributable to variation in the definition of EPCs, as well as a difference in the interaction between EPCs and other cells involved in vascular control such as pericytes, smooth muscle cells and macrophages. For EPCs to be used regularly in clinical practice, agreement on definitions of EPC subtypes is needed, and recognition that function of EPCs (rather than number) may be a better marker of vascular risk in certain CVD risk states. The present review focuses on the identification of measures to improve individual risk stratification and, further, to potentially individualize patient care to address specific EPC functional abnormalities. Herein, we describe that future therapeutic use of EPCs will probably rely on a combination of strategies, including optimization of the function of adjunct cell types to prime tissues for the effect of EPCs.


2012 ◽  
Vol 206 (9) ◽  
pp. 1480-1481
Author(s):  
C. T. Costiniuk ◽  
B. M. Hibbert ◽  
L. G. Filion ◽  
E. R. O'Brien ◽  
J. B. Angel

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1796-1796
Author(s):  
Jamie Case ◽  
Laura E. Mead ◽  
Hilary A. White ◽  
Mohammad R. Saadatzadeh ◽  
Mervin C. Yoder ◽  
...  

Abstract Endothelial progenitor cells (EPCs) are currently used for angiogenic therapies or as biomarkers to assess cardiovascular disease risk and progression. However, there is no uniform definition of an EPC, which complicates interpretation of prior EPC studies. EPCs are primarily defined by expression of cell surface antigens. The most widely cited definition of an EPC is a cell which co-expresses CD34, AC133 and VEGFR-2. Importantly, these antigens are also expressed on the most primitive population of hematopoietic progenitor cells (HPCs), including high proliferative potential- (HPP-) and low proliferative potential-colony forming cells (LPP-CFCs). Remarkably, CD34+AC133+VEGFR-2+ cells have never been isolated and plated in endothelial cell (EC) or hematopoietic cell clonogenic assays to determine what cell progeny can be derived from a CD34+AC133+VEGFR-2+ cell. Utilizing human umbilical cord blood (CB), an enriched source of both EPCs and HPCs, we isolated and purified CD34+AC133+VEGFR-2+ cells by FACS and assayed for the presence of clonogenic endothelial CFCs (ECFCs) plus HPP- and LPP-CFCs. Surprisingly, CD34+AC133+VEGFR-2+ cells do not form ECFCs under any culture conditions previously described for outgrowth of EPCs. However, consistent with a HPC phenotype, CD34+AC133+VEGFR-2+ cells formed both HPP- and LPP-CFCs in multiple independent assays. In addition, all CD34+AC133+VEGFR-2+ cells were shown to co-express the specific hematopoietic cell surface antigen, CD45, which is not present on ECs. Based on this information, we plated CD34+CD45+ or CD34+CD45− cells to determine if EPCs could be separated from HPCs on the basis of CD45 expression. In multiple independent assays, CD34+CD45+ cells consistently formed both HPP- and LPP-CFCs but not EC colonies. In contrast, CD34+CD45− cells form EC colonies but not hematopoietic cell colonies. Taken together, these data demonstrate that circulating CD34+AC133+VEGFR-2+ cells are HPCs and the biologic mechanism for their correlation with cardiovascular disease needs to be re-examined. Furthermore, studies focused on determining the angiogenic potential of CD34+CD45− cells are needed given that this cell population harbors ECFCs.


2009 ◽  
Vol 89 (1) ◽  
pp. 147-191 ◽  
Author(s):  
Philippe Lefebvre ◽  
Bertrand Cariou ◽  
Fleur Lien ◽  
Folkert Kuipers ◽  
Bart Staels

The incidence of the metabolic syndrome has taken epidemic proportions in the past decades, contributing to an increased risk of cardiovascular disease and diabetes. The metabolic syndrome can be defined as a cluster of cardiovascular disease risk factors including visceral obesity, insulin resistance, dyslipidemia, increased blood pressure, and hypercoagulability. The farnesoid X receptor (FXR) belongs to the superfamily of ligand-activated nuclear receptor transcription factors. FXR is activated by bile acids, and FXR-deficient ( FXR−/−) mice display elevated serum levels of triglycerides and high-density lipoprotein cholesterol, demonstrating a critical role of FXR in lipid metabolism. In an opposite manner, activation of FXR by bile acids (BAs) or nonsteroidal synthetic FXR agonists lowers plasma triglycerides by a mechanism that may involve the repression of hepatic SREBP-1c expression and/or the modulation of glucose-induced lipogenic genes. A cross-talk between BA and glucose metabolism was recently identified, implicating both FXR-dependent and FXR-independent pathways. The first indication for a potential role of FXR in diabetes came from the observation that hepatic FXR expression is reduced in animal models of diabetes. While FXR−/−mice display both impaired glucose tolerance and decreased insulin sensitivity, activation of FXR improves hyperglycemia and dyslipidemia in vivo in diabetic mice. Finally, a recent report also indicates that BA may regulate energy expenditure in a FXR-independent manner in mice, via activation of the G protein-coupled receptor TGR5. Taken together, these findings suggest that modulation of FXR activity and BA metabolism may open new attractive pharmacological approaches for the treatment of the metabolic syndrome and type 2 diabetes.


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