Effects of atorvastatin on circulating CD34+/CD133+/ CD45- progenitor cells and indices of angiogenesis (vascular endothelial growth factor and the angiopoietins 1 and 2) in atherosclerotic vascular disease and diabetes mellitus

Endothelial progenitor cells as biomarkers of diabetes-related cardiovascular complications

Diabetes mellitus (DM) constitutes a chronic metabolic disease characterized by elevated levels of blood glucose which can also lead to the so-called diabetic vascular complications (DVCs), responsible for most of the morbidity, hospitalizations and death registered in these patients. Currently, different approaches to prevent or reduce DM and its DVCs have focused on reducing blood sugar levels, cholesterol management or even changes in lifestyle habits. However, even the strictest glycaemic control strategies are not always sufficient to prevent the development of DVCs, which reflects the need to identify reliable biomarkers capable of predicting further vascular complications in diabetic patients. Endothelial progenitor cells (EPCs), widely known for their potential applications in cell therapy due to their regenerative properties, may be used as differential markers in DVCs, considering that the number and functionality of these cells are affected under the pathological environments related to DM. Besides, drugs commonly used with DM patients may influence the level or behaviour of EPCs as a pleiotropic effect that could finally be decisive in the prognosis of the disease. In the current review, we have analysed the relationship between diabetes and DVCs, focusing on the potential use of EPCs as biomarkers of diabetes progression towards the development of major vascular complications. Moreover, the effects of different drugs on the number and function of EPCs have been also addressed.

Diabetes and Its Cardiovascular Complications: Comprehensive Network and Systematic Analyses

Diabetes mellitus is a worldwide health problem that usually comes with severe complications. There is no cure for diabetes yet and the threat of these complications is what keeps researchers investigating mechanisms and treatments for diabetes mellitus. Due to advancements in genomics, epigenomics, proteomics, and single-cell multiomics research, considerable progress has been made toward understanding the mechanisms of diabetes mellitus. In addition, investigation of the association between diabetes and other physiological systems revealed potentially novel pathways and targets involved in the initiation and progress of diabetes. This review focuses on current advancements in studying the mechanisms of diabetes by using genomic, epigenomic, proteomic, and single-cell multiomic analysis methods. It will also focus on recent findings pertaining to the relationship between diabetes and other biological processes, and new findings on the contribution of diabetes to several pathological conditions.

Effects of Low-Dose Atorvastatin on the Peripheral Blood Mononuclear Cell Secretion of Angiogenic Factors in Type 2 Diabetes

The aim of this study was to investigate the influence of statins on the secretion of angiogenesis mediators by the peripheral blood mononuclear cells (PBMCs) derived from patients suffering from type 2 diabetes. The study group comprised 30 participants and included: 10 statin-treated patients with diabetes, 10 statin-free diabetic subjects, and 10 statin-free non-diabetic individuals. PBMCs isolated from the blood were cultured in vitro in standard conditions and in an environment mimicking hyperglycemia. Culture supernatants were evaluated for VEGF, MCP-1, Il-10, and Il-12 by flow cytometry using commercial BD^TM. Cytometric Bead Array tests. The secretion of VEGF, MCP-1 and Il-12 by PBMCs, cultured both in standard and hyperglycemic conditions, was significantly lower in the statin-treated patients with type 2 diabetes in comparison with the statin-free diabetic patients. Conversely, the secretion of Il-10 was higher in the statin-treated than in the statin-free diabetic patients. VEGF, MCP-1 and Il-12 levels in PBMCs supernatants from the glucose-containing medium were higher than those from the standard medium in each of the diabetic groups. The results of the study suggest that statins in low doses exhibit an antiangiogenic activity, reducing the secretion of potent proangiogenic factors, such as VEGF and MCP-1, and increasing the secretion of antiangiogenic Il-10 by PBMCs, also under hyperglycemic conditions characteristic for type 2 diabetes.

Dual effects of atorvastatin on angiogenesis pathways in the differentiation of mesenchymal stem cells

Atorvastatin (ATO) can improve the transplantation efficacy of mesenchymal stem cells (MSCs) after acute myocardial infarction. The present study aimed at ATO effects on the angiogenesis-signaling pathways from MSCs' differentiation to tissue angiogenesis. MSCs were first prepared from BALB/c mouse bone marrow. MTT assay was then done for the biodegradability of MSCs with the extracellular matrix. After that, the differentiation of cells into the bone and fat tissues was confirmed by Alizarin and Oil Red O staining. The extracellular matrix was then combined with the cells to the implant. Animals were intraperitoneally treated with ATO (2 and 40 mg/kg, daily) three days before cell transplantation to one week after. Finally, the assays were carried out by electron microscopy, immunocytochemistry, ELISA, Western blot, and RT-qPCR techniques. A phase-contrast microscope confirmed the morphology of cells. The cell differentiation into bone and fat tissues was confirmed by Alizarin red staining and flow cytometry, and the cell proliferation was confirmed by MTT assay. Unlike ATO 40 mg/kg group, ATO 2 mg/kg was significantly increased the CD31, eNOS, podocalyxin, von Willibrand factor, and alpha-smooth muscle actin proteins levels compared to the control group in vitro experiment. The expression of CD31 and VEGF proteins, as angiogenesis markers, and Ki-67 protein, as a proliferation marker, was significantly higher in a low dose of ATO (2 mg/kg) than that of the control group in vivo experiment. Unlike ATO 40 mg/kg, the expression levels of ERK, AKT, NF-ҝB, Rho, STAT3, Ets-1, HIF-1α, and VEGF proteins and genes were significantly increased in ATO 2 mg/kg compared to the control. A low dose of ATO can be a beneficial tool in the function of MSCs and their differentiation to tissue angiogenesis.

Neovascularization: The Main Mechanism of MSCs in Ischemic Heart Disease Therapy

Mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been shown to effectively limit the infarct area in numerous clinical and preclinical studies. However, the primary mechanism associated with this activity in MSC transplantation therapy remains unclear. Blood supply is fundamental for the survival of myocardial tissue, and the formation of an efficient vascular network is a prerequisite for blood flow. The paracrine function of MSCs, which is throughout the neovascularization process, including MSC mobilization, migration, homing, adhesion and retention, regulates angiogenesis and vasculogenesis through existing endothelial cells (ECs) and endothelial progenitor cells (EPCs). Additionally, MSCs have the ability to differentiate into multiple cell lineages and can be mobilized and migrate to ischemic tissue to differentiate into ECs, pericytes and smooth muscle cells in some degree, which are necessary components of blood vessels. These characteristics of MSCs support the view that these cells improve ischemic myocardium through angiogenesis and vasculogenesis. In this review, the results of recent clinical and preclinical studies are discussed to illustrate the processes and mechanisms of neovascularization in ischemic heart disease.

Danhong injection mobilizes endothelial progenitor cells to repair vascular endothelium injury via upregulating the expression of Akt, eNOS and MMP-9

BACKGROUD

Endothelial progenitor cells (EPCs) have been characterized as one of the key effectors of endothelial healing. The effect of Danhong injection (DHI), the most widely prescribed Chinese medicine for coronary heart disease (CHD), on EPCs mobilization remains unclear.

PURPOSE

We aimed to assess the effect of DHI on EPCs mobilization to repair percutaneous coronary intervention (PCI) induced vascular injury, and to investigate the characteristics and potential mechanism of DHI on EPCs mobilization.

METHOD

Forty-two patients with CHD underwent PCI and received stent implantation were enrolled in a Phase II clinical trials. All patients received routine western medical treatment after PCI, patients of DHI group received DHI in addition. The levels of CECs, cytokines (vWF, IL-6, CRP) and EPCs were analyzed at baseline, post-PCI and after treatment. To investigate the characteristics of DHI on EPCs mobilization, 12 healthy volunteers received intravenous infusion of DHI once and the other 12 received for 7 days. EPCs enumeration were done at a series of time points. At last we tested the effect of DHI and three chemical constituents of DHI (danshensu; lithospermic acid, LA; salvianolic acid D, SaD) on EPCs level and expression of Akt, eNOS and MMP-9 in bone marrow cells of myocardial infarction (MI) mice.

RESULTS

In the DHI group the angina symptoms were improved, the levels of cytokines and CECs were reduced; while EPCs population was increased after treatment. In the phase I clinical trials, EPCs counts reached a plateau phase in 9 h and maintained for more than 10 h after a single dose. After continuous administration, EPCs levels plateaued on the 3rd or 4th day, and maintain till 1 day after the withdrawal, then its levels gradually declined. DHI treatment induced a timely dependent mobilization of EPCs. DHI promoted EPCs mobilization via upregulating the expression of Akt, eNOS and MMP-9 in BM. LA and SaD have played a valuable role in EPCs mobilization.

CONCLUSION

These initial results demonstrated that DHI is effective in alleviating endothelial injury and promoting endothelial repair through enhancing EPCs mobilization and revealed the effect feature and possible mechanisms of DHI in mobilizing EPCs.

Atorvastatin and Conditioned Media from Atorvastatin-Treated Human Hematopoietic Stem/Progenitor-Derived Cells Show Proangiogenic Activity In Vitro but Not In Vivo

Myeloid angiogenic cells (MAC) derive from hematopoietic stem/progenitor cells (HSPCs) that are mobilized from the bone marrow. They home to sites of neovascularization and contribute to angiogenesis by production of paracrine factors. The number and function of proangiogenic cells are impaired in patients with diabetes or cardiovascular diseases. Both conditions can be accompanied by decreased levels of heme oxygenase-1 (HMOX1), cytoprotective, heme-degrading enzyme. Our study is aimed at investigating whether precursors of myeloid angiogenic cells (PACs) treated with known pharmaceuticals would produce media with better proangiogenic activity in vitro and if such media can be used to stimulate blood vessel growth in vivo. We used G-CSF-mobilized CD34⁺ HSPCs, FACS-sorted from healthy donor peripheral blood mononuclear cells (PBMCs). Sorted cells were predominantly CD133⁺. CD34⁺ cells after six days in culture were stimulated with atorvastatin (AT), acetylsalicylic acid (ASA), sulforaphane (SR), resveratrol (RV), or metformin (Met) for 48 h. Conditioned media from such cells were then used to stimulate human aortic endothelial cells (HAoECs) to enhance tube-like structure formation in a Matrigel assay. The only stimulant that enhanced PAC paracrine angiogenic activity was atorvastatin, which also had ability to stabilize endothelial tubes in vitro. On the other hand, the only one that induced heme oxygenase-1 expression was sulforaphane, a known activator of a HMOX1 inducer—NRF2. None of the stimulants changed significantly the levels of 30 cytokines and growth factors tested with the multiplex test. Then, we used atorvastatin-stimulated cells or conditioned media from them in the Matrigel plug in vivo angiogenic assay. Neither AT alone in control media nor conditioned media nor AT-stimulated cells affected numbers of endothelial cells in the plug or plug's vascularization. Concluding, high concentrations of atorvastatin stabilize tubes and enhance the paracrine angiogenic activity of human PAC cells in vitro. However, the effect was not observed in vivo. Therefore, the use of conditioned media from atorvastatin-treated PAC is not a promising therapeutic strategy to enhance angiogenesis.

Response of vascular mesenchymal stem/progenitor cells to hyperlipidemia

Hyperlipidemia is a risk factor for atherosclerosis that is characterized by lipid accumulation, inflammatory cell infiltration, and smooth muscle cell proliferation. It is well known that hyperlipidemia is a stimulator for endothelial dysfunction and smooth muscle cell migration during vascular disease development. Recently, it was found that vessel wall contains a variable number of mesenchymal stem cells (MSCs) that are quiescent in physiological conditions, but can be activated by a variety of stimuli, e.g., increased lipid level or hyperlipidemia. Vascular MSCs displayed characteristics of stem cells which can differentiate into several types of cells, e.g., smooth muscle cells, adipocytic, chondrocytic, and osteocytic lineages. In vitro, lipid loading can induce MSC migration and chemokines secretion. After MSC migration into the intima, they play an essential role in inflammatory response and cell accumulation during the initiation and progression of atherosclerosis. In addition, MSC transplantation has been explored as a therapeutic approach to treat atherosclerosis in animal models. In this review, we aim to summarize current progress in characterizing the identity of vascular MSCs and to discuss the mechanisms involved in the response of vascular stem/progenitor cells to lipid loading, as well as to explore therapeutic strategies for vascular diseases and shed new light on regenerative medicine.

The association between interleukin-19 concentration and diabetic nephropathy

Background

Interleukin-19 (IL-19) is a newly discovered cytokine belonging to the Interleukin-10(IL-10) family. IL-19 have indispensable functions in many inflammatory processes and also can induce the angiogenic potential of endothelial cells. The purpose of present study was to investigate the relation of serum interleukin-19 (IL-19) levels with diabetic nephropathy (DN).

Methods

Two hundred study groups of patients with type 2 diabetes mellitus (T2DM) (109 males and 91 females) were recruited, included normoalbuminuria(n = 102), microalbuminuria(n = 72) and macroalbuminuria(n = 26) . The 50 healthy blood donors were enrolled for the control group. All subjects were assessed for: IL-19, High-sensitivity C-reactive protein (Hs-CRP), Cystatin C, urinary albumin excretion rate (UAE) and glycosylated hemoglobin A1c(HbA1c).

Results

The serum IL-19 levels in DN patients were found to be significantly higher compared to controls. IL-19 levels were significantly positively correlated with Hs-CRP, Cystatin C, UAE and HbA1c(r = 0.623, 0.611,0.591 and 0.526 respectively, P < 0.01). Multivariable logistic regression analysis showed IL-19 levels (P = 0.01) were found to be independently associated with patients with DN.

Conclusions

IL-19 is significantly positive correlated with UAE and Cystatin C. IL-19 may play an important role that contributes to the progression of diabetic nephropathy.

Vascular Endothelial Growth Factor Inhibitors for Diabetic Retinopathy

The prevalence of diabetes is growing at epidemic rates in the USA. Diabetic retinopathy develops in a large proportion of patients and is a leading cause of blindness worldwide. Systemic management of diabetic retinopathy has included glycemic, hypertension, and lipid control. Local ophthalmic treatment in the form of focal/grid or panretinal laser photocoagulation has been shown to prevent vision loss in diabetic edema and proliferative diabetic retinopathy, respectively. The introduction of anti-vascular endothelial growth factor for diabetic macular edema and retinopathy has provided clinicians with improved clinical outcomes with potentially less damaging effects than laser.

Modulating putative endothelial progenitor cells for the treatment of endothelial dysfunction and cardiovascular complications in diabetes

Diabetes induces a decrease in the number and function of different pro-angiogenic cell types generically designated as putative endothelial progenitor cells (EPC), which encompasses cells from myeloid origin that act in a paracrine fashion to promote angiogenesis and putative "true" EPC that contribute to endothelial replacement. This not only compromises neovasculogenesis in ischemic tissues but also impairs, at an early stage, the reendotheliziation process at sites of injury, contributing to the development of endothelial dysfunction and cardiovascular complications. Hyperglycemia, insulin resistance and dyslipidemia promote putative EPC dysregulation by affecting the SDF-1/CXCR-4 and NO pathways and the p53/SIRT1/p66Shc axis that contribute to their mobilization, migration, homing and vasculogenic properties. To optimize the clinical management of patients with hypoglycemic agents, statins and renin-angiotensin system inhibitors, which display pleiotropic effects on putative EPC, is a first step to improve their number and angiogenic potential but specific strategies are needed. Among them, mobilizing therapies based on G-CSF, erythropoietin or CXCR-4 antagonism have been developed to increase putative EPC number to treat ischemic diseases with or without prior cell isolation and transplantation. Growth factors, genetic and pharmacological strategies are also evaluated to improve ex vivo cultured EPC function before transplantation. Moreover, pharmacological agents increasing in vivo the bioavailability of NO and other endothelial factors demonstrated beneficial effects on neovascularization in diabetic ischemic models but their effects on endothelial dysfunction remain poorly evaluated. More experiments are warranted to develop orally available drugs and specific agents targeting p66Shc to reverse putative EPC dysfunction in the expected goal of preventing endothelial dysfunction and diabetic cardiovascular complications.

Association between interleukin-19 and angiopoietin-2 with vascular complications in type 2 diabetes

Aims/Introduction

The aim of the present study was to investigate the role of interleukin‐19 (IL‐19) in angiogenesis of type 2 diabetes mellitus with complications, and to assess the relationship of serum IL‐19 and angiopoietin‐2 (Ang‐2) in type 2 diabetes mellitus.

Materials and Methods

The group studied comprised of 240 patients with type 2 diabetes mellitus (132 men and 108 women), and included macrovascular complications, microvascular complications and type 2 diabetes mellitus without vascular complications. The control group consisted of 50 healthy blood donors. All participants were evaluated for: IL‐19, Ang‐2, fasting plasma glucose, fasting insulin and glycosylated hemoglobin.

Results

The serum IL‐19 levels of type 2 diabetes mellitus patients with angiopathy were found to be significantly higher compared with patients without angiopathy. IL‐19 levels were significantly positively correlated with Ang‐2, homeostasis model assessment for insulin resistance and glycosylated hemoglobin (r = 0.769, 0.523 and 0.491, respectively, P < 0.01). In multivariable logistic regression analysis, IL‐19 levels (P = 0.01) were found to be independently associated with patients with type 2 diabetes mellitus complications.

Conclusions

These data are the first to implicate the association between the IL‐19 and type 2 diabetes mellitus with vascular complications. IL‐19 is significantly positively correlated with Ang‐2. The potential role of IL‐19 and Ang‐2 in the pathogenesis of vascular complications in type 2 diabetes could warrant further study.

Influence of exercise training on proangiogenic TIE-2 monocytes and circulating angiogenic cells in patients with peripheral arterial disease

BACKGROUND

Inflammation is the driving force in atherosclerosis. One central strategy in the treatment of peripheral arterial disease (PAD) is the promotion of angiogenesis. Here, proangiogenic Tie-2 expressing monocytes (TEM) and circulating angiogenic cells (CAC) play a crucial role. Exercise training (ET) is recommended in PAD patients at Fontaine stage II to promote angiogenesis.

METHODS

40 patients with intermittend claudication (IC) [2 groups: supervised ET (SET) vs. non-supervised ET (nSET), each n = 20] and 20 healthy controls were included in the study. Analysis of TEM and CAC was performed from whole blood by flow-cytometry. TEM were identified via CD45, CD86, CD14, CD16 and analysed for the expression of Tie-2. CAC were identified via their expression of CD45 (CD45dim), CD34 and VEGF-R2 (CD309/KDR). Follow up was performed after mean of 7.65 ± 1.62 months.

RESULTS

In comparison to healthy controls, we found increased proportions of CAC (p < 0.0001) and similar TEM numbers in both ET groups. At follow-up (FU) TEM poroportions increased (p < 0.001) and CAC proportions decreased (p < 0.01), but both more significantly in SET (p < 0.001) than nSET (p = 0.01). Only in SET fibrinogen levels decreased and VEGF-A increased (both p < 0.05). Finally, we found in both ET groups a significant increase in absolute walking distance but with a higher individual increase in SET (p < 0.01). TEM and CAC proportions correlated inversely with the absolute walking distance (CAC: r = -0.296, p = 0.02; TEM: r = -0.270, p = 0.04) as well as with ABI (CAC: r = -0.394, p < 0.01; TEM: r = -0.382, p < 0.01).

CONCLUSIONS

ET influences the distribution of CAC and TEM proportions. nSET, although still effective in regard to an improved walking distance, is less effective in the influence of proangiogenic cells and inflammatory burden than SET. Our results indicate SET to be a more preferential exercise form, supporting the necessity to establish more SET programs.

Does statin therapy reduce plasma VEGF levels in humans? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The effect of statins on plasma concentrations of vascular endothelial growth factor (VEGF), the main angiogenic growth factor with pro-inflammatory and atherogenic properties, is controversial. A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to obtain a conclusive result in humans.

METHODS

PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched to identify RCTs investigating the impact of statins on plasma VEGF concentrations. A random-effects model and the generic inverse variance method were used for quantitative data synthesis. Meta-regression, sensitivity analysis and publication bias assessments were performed using standard methods.

RESULTS

Eight RCTs examining the effects of statins on plasma VEGF concentrations were included. Meta-analysis suggested a significant reduction of plasma VEGF levels following statin therapy (weighed mean difference: -19.88 pg/mL, 95% CI: -35.87, -3.89, p=0.015). VEGF reductions were observed in the subsets of trials with treatment durations ≥4 weeks (-19.54, -37.78, -1.30, p=0.036), LDL-C reductions ≥50 mg/dL (-28.59, -43.68, -13.50, p<0.001), lipophilic statins (-22.31, -40.65, -3.98, p=0.017), and diseased populations (-21.08, -39.97, -2.18, p=0.029), but not in the opposite subsets. Meta-regression also suggested a significant association between changes in plasma VEGF levels and LDL-C changes, treatment duration, but not molar dose of statins.

CONCLUSIONS

These results suggest a significant reduction in plasma VEGF concentrations following statin therapy. This effect depends on duration of treatment, LDL-lowering activity, lipophilicity of statins, and health status of studied individuals. Further RCTs are needed to explore if the VEGF reduction is implicated in the statin benefits on cardiovascular outcomes.

Serum angiopoietin-2 is associated with angiopathy in type 2 diabetes mellitus

PURPOSE

The aim of the present study was to investigate the association of serum levels of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) with angiopathy in type 2 diabetes mellitus (T2DM).

METHODS

The group studied comprised of 120 patients with T2DM (68 males and 52 females), included macroangiopathy complications, microvascular disease and diabetic without vascular disease. The control group consisted of 50 healthy blood donors. Ang-1, Ang-2, fasting plasma glucose (FBG), fasting insulin (FINS) and HbA1c were assessed.

RESULTS

The serum Ang-2 levels of T2DM patients with angiopathy were found to be significantly higher compared to patients without angiopathy. Ang-2 levels were significantly positively correlated with homeostasis model assessment for insulin resistance (HOMA-IR) and glycosylated hemoglobin A1c (HbA1c) (r=0.577 and 0.504, respectively, P<0.01). In contrast, there was no significant correlation between Ang-1 levels and HOMA-IR (P>0.05). In multivariable logistic regression analysis, Ang-2 levels (P=0.02) were found to be independently associated with patients with T2DM angiopathy.

CONCLUSIONS

An association between the Ang-2 and T2DM with vascular complications was found.

Change of walking distance in intermittent claudication: impact on inflammation, oxidative stress and mononuclear cells: a pilot study

BACKGROUND

Atherosclerosis is a chronic inflammatory process involving the immune system and formation of reactive oxygen species (ROS). We investigated changes of mononuclear blood cells and ROS production in relation to the walking distance of patients with intermittent claudication during home-based exercise training.

METHODS

Forty patients with intermittent claudication were asked to perform a home-based exercise training for a mean time of 12 months. ROS formation was measured using the luminol analogue L-012. Peripheral blood leucocytes [monocytes, polymorphonuclear neutrophils (PMN) and dendritic cells (DC)] were analysed by flow cytometry and analysed for the expression of major inflammatory surface molecules.

RESULTS

At follow-up, patients showed an increased walking distance and reduced ROS production upon stimulation with a phorbol ester derivative (PDBu) (p < 0.01). Monocytes changed their inflammatory phenotype towards an increased anti-inflammatory CD14(++)CD16(-) subpopulation (p < 0.0001). Adhesion molecules CD11b, CD11c and TREM-1 on monocytes and PMN decreased (all p < 0.01). On DC expression of HLA-DR, CD86 or CD40 decreased at follow-up. Inflammatory markers like fibrinogen, C-reactive protein or soluble TREM-1 (sTREM-1) decreased over the observation period. Finally, we found a close relation of sTREM-1 with the walking distance, fibrinogen and ROS production.

CONCLUSIONS

We observed an amelioration of the proinflammatory phenotype on monocytes, DC and PMN, as well as a reduced ROS production in PAD patients under home-based exercise, paralleled by an increased walking distance. Our data suggest that a reduced inflammatory state might be achieved by regular walking exercise, possibly in a dimension proportionately to changes in walking distance.

Diabetes and hyperlipidemia induce dysfunction of VSMCs: contribution of the metabolic inflammation/miRNA pathway

Vascular endothelial cell injury is considered to be the major factor inducing vascular complications in metabolic diseases and plays an important role in other organ damage. With diabetic and hyperlipidemic rats and cultured VSMCs, the present study was aimed at investigating whether the early damage of VSMCs during metabolic diseases plays a critical role in vascular dysfunction and the underlying mechanisms and would be a promising treatment target. With diabetic and hyperlipidemic rats and cultured VSMCs, the changes and relationships of vascular relaxation and contractile function to the vital organ damage and the underlying mechanisms were investigated; meanwhile, the protective and preventive effects of lowering blood lipid and glucose and inhibition of diabetes and hyperlipidemia-induced vascular hyperreactivity were observed. Diabetic and hyperlipidemic rats presented hyperreactivity in vascular contractile response in the early stages. Hyperglycemia and hyperlipidemia directly affected the contractile function of VSMCs. Early application of fasudil, a specific antagonist of Rho kinase, significantly alleviated diabetes and hyperlipidemia-induced organ damage by inhibiting vascular hyperreactivity. Diabetes and hyperlipidemia-induced inflammatory response could upregulate the expression of connexins and Rho kinase by selective downregulation of the expression of miR-10a, miR-139b, miR-206, and miR-222. These findings suggest that hyperglucose and lipid may directly impair VSMCs and induce vascular hyperreactivity in the early stages. Metabolic inflammation-induced changes in the miRNA-connexin/Rho kinase regulatory pathway are the main mechanism for vascular hyperreactivity and organ damage. Measures inhibiting vascular hyperreactivity are promising for the prevention of organ damage induced by metabolic diseases.

Effect of atorvastatin on the angiogenic responsiveness of coronary endothelial cells in normal and streptozotocin (STZ) induced diabetic rats

Atorvastatin, a lipid lowering agent, possesses various pleiotropic vasculoprotective effects, but its role in coronary angiogenesis is still controversial. Our objective was to study the effects of atorvastatin on the angiogenic responsiveness of coronary endothelial cells (cEC) from normal and diabetic rats. Male Wistar rats were distributed among 9 groups; (i) normal rats, (ii) 30 day diabetic rats, (iii) 60 day diabetic rats, (iv) normal rats administered a low dose of atorvastatin (1 mg/kg body mass, per oral (p.o.), for 15 days); (v) 30 day diabetic rats administered a low dose of atorvastatin; (vi) 60 day diabetic rats administered a low dose of atorvastatin; (vii) normal rats administered a high dose of atorvastatin (5 mg/kg, p.o., for 15 days); (viii) 30 day diabetic rats administered a high dose of atorvastatin; (ix) 60 day diabetic rats administered a high dose of atorvastatin. Each group was further divided into 2 subgroups, (i) sham ischemia-reperfusion and (ii) rats hearts that underwent ischemia-reperfusion. Angiogenic responsiveness the and nitric oxide (NO) releasing properties of the subgroups of cECs were studied using a chorioallantoic membrane assay and the Griess method, respectively. Atorvastatin treatment significantly increased VEGF-induced angiogenic responsiveness and the NO-releasing properties of cECs from all of the subgroups, compared with their respective non-treated subgroups except for the late-phase diabetic rat hearts that underwent ischemia-reperfusion, and the high dose of atorvastatin treatment groups. These effects of atorvastatin were significantly inhibited by pretreatment of cECs with l-NAME, wortmannin, and chelerythrine. Thus, treatment with a low dose of atorvastatin improves the angiogenic responsiveness of the cECs from normal and diabetic rats, in the presence of VEGF, via activation of eNOS-NO release.

Specific role of impaired glucose metabolism and diabetes mellitus in endothelial progenitor cell characteristics and function

The disease burden of diabetes mellitus (DM) and its associated cardiovascular complications represent a growing and major global health problem. Recent studies suggest that circulating exogenous endothelial progenitor cells (EPCs) play an important role in endothelial repair and neovascularization at sites of injury or ischemia. Both experimental and clinical studies have demonstrated that hyperglycemia related to DM can induce alterations to EPCs. The reduction and dysfunction of EPCs related to DM correlate with the occurrence and severity of microvascular and macrovascular complications, suggesting a close mechanistic link between EPC dysfunction and impaired vascular function/repair in DM. These alterations to EPCs, likely mediated by multiple pathophysiological mechanisms, including inflammation, oxidative stress, and alterations in Akt and the nitric oxide pathway, affect EPCs at multiple stages: differentiation and mobilization in the bone marrow, trafficking and survival in the circulation, and homing and neovascularization. Several different therapeutic approaches have consequently been proposed to reverse the reduction and dysfunction of EPCs in DM and may represent a novel therapeutic approach to prevent and treat DM-related cardiovascular complications.

Role of statin in atrial fibrillation-related stroke: an angiographic study for collateral flow

BACKGROUND

Currently, intensive lipid lowering is recommended in patients with atherosclerotic ischemic stroke or transient ischemic attack. However, the role of statin in cardioembolic stroke is unclear. We investigated the association of statin with pretreatment collateral status in cardioembolic stroke.

METHODS

A collaborative study from two stroke centers in distinct geographic regions included consecutive patients with acute middle cerebral artery (MCA) infarction due to atrial fibrillation (AF) who underwent cerebral angiography. The relationship between pretreatment collateral grade and the use/dose of statin at stroke onset was assessed. The angiographic collateral grade was evaluated according to the ASITN/SIR Collateral Flow Grading System.

RESULTS

Ninety-eight patients (76 statin-naïve, 22 statin users) were included. Compared with statin-naïve patients, statin users were older and more frequently had hypertension, hyperlipidemia and coronary heart disease. Excellent collaterals (grade 3-4) were more frequently observed in statin users (11 patients, 50%) than in statin-naïve patients (21 patients, 27.6%; p = 0.049). The use of atorvastatin 10 mg equivalent or higher doses of statin was associated with excellent collaterals (p for trend = 0.025). In multiple regression analysis, prestroke statin use was independently associated with excellent collaterals (odds ratio, 7.841; 95% confidence interval, CI, 1.96-31.363; p = 0.004).

CONCLUSIONS

Premorbid use of statin in AF patients is associated with excellent collateral flow. Although most statin trials excluded patients with cardioembolic stroke, our data suggests the possibility that statin may be beneficial in AF-related stroke

Statins in low doses reduce VEGF and bFGF serum levels in patients with type 2 diabetes mellitus

BACKGROUND/AIMS

Recent experimental research revealed that statins at low doses induce angiogenesis, which in turn may be related to the course of atherosclerosis. There are no clinical studies evaluating the effect of 'low-dose' statins on serum levels of angiogenesis regulators in diabetic subjects. We aimed to explain how low doses of statins modify the serum concentrations of two potent proangiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), in patients with type 2 diabetes.

METHODS

Measurements of fasting glucose level, HbA1c, 1,5-anhydro-D-glucitol and lipid profile were taken from 47 patients with type 2 diabetes treated with low doses of atorvastatin (10 mg daily) or simvastatin (10-20 mg daily), from 45 statin-free patients with type 2 diabetes and from 23 nondiabetic subjects. Measurements of VEGF and bFGF in serum were taken using the BD™ Cytometric Bead Array.

RESULTS AND CONCLUSION

Statins used in low doses in patients with type 2 diabetes reduce the serum concentration of VEGF and bFGF which suggests antiangiogenic potential of these doses. Nevertheless, this effect could be neutralized by postprandial hyperglycemia.

The effect of statin therapy withdrawal on monocyte subsets

BACKGROUND

Three functionally distinct monocyte subsets have been identified. Statins are of undoubted effect in atherosclerosis and have numerous pleiotropic effects that contribute to their clinical success, but the effect of these drugs on monocyte subsets is unclear. We hypothesised a beneficial effect of statins on key receptor expression by monocyte subsets.

MATERIAL AND METHODS

Effects of temporal (2 weeks) cessation of statin therapy by 66 patients with stable coronary artery disease on monocyte subsets [CD14++CD16-CCR2+ (Mon1), CD14++CD16+CCR2+ (Mon2) and CD14+CD16++CCR2- (Mon3)], their aggregates with platelets and their expression of a number of receptors involved in inflammation (IL-6 receptor), adhesion [vascular cell adhesion molecule (VCAM)], angiogenesis [vascular endothelial growth factor (VEGF)] and repair were assessed by flow cytometry.

RESULTS

Statin cessation did not lead to any significant changes in absolute numbers of monocyte subsets or the degree of their aggregation with platelets. All monocyte subsets showed significant downregulation of expression of vascular endothelial factor receptor 2, Tie2 and Toll-like receptor-4 (TLR4; all changes P < 0·01). Expression of CXCR4 was only reduced in Mon1 cells (P = 0·013). There was no significant change in the expression of CD14, CD16, CCR4, IL6 receptor and VCAM (all P = NS).

CONCLUSIONS

Statin withdrawal does not affect counts of any of monocyte subsets, but leads to downregulation of expression of TLR4 and receptors related to angiogenesis on all subsets, as well as a decrease in density of CXCR4 expression on 'classical' Mon1. These data provide further support of pleiotropic effects of statins and their effects on monocyte pro-angiogenic and proreparative characteristics.

Anti-atherogenic effects of statins: Impact on angiopoietin-2 release from endothelial cells

Beyond lipid lowering, statins are supposed to exert pleiotropic effects positively influencing the progression of atherosclerotic lesions. The development of such lesions is associated with increased release of angiopoietin-2 (Ang-2), an endothelial cell-specific protein growth factor stored in Weibel-Palade bodies (WPBs). The aim of our study was to examine whether statin pretreatment influences the release of Ang-2 from endothelial cells. Stimulation of HUVECs and HMVECs with PMA, thrombin or histamine resulted in significant release of Ang-2, as evidenced by ELISA. Pretreatment with simvastatin and mevastatin suppressed this release to basal level, while pravastatin had no effect. Simvastatin itself increased nitric oxide (NO, EC number 1.14.13.39) synthesis, measured by Griess reaction. Combining the statin pretreatment with the eNOS inhibitor L-NNA as well as bypassing the HMG-CoA reductase (EC number: 1.1.1.34) by adding mevalonic acid or geranyl pyrophosphate restored the exocytotic effect of PMA. Immunofluorescence microscopy showed that depletion of WPBs upon PMA stimulation ceased after pretreatment with simvastatin. This study demonstrates a potent suppressive effect of statins on the release of Ang-2 from endothelial cells. Regarding its harmful effects in the development of atherosclerotic lesions, our data provide further insight into the mechanisms of the anti-atherogenic potential of statins.

Does drug therapy reverse endothelial progenitor cell dysfunction in diabetes?

Endothelial progenitor cells (EPCs) are vital for the maintenance and repair of the endothelium. Decreased EPC number and function have been associated with increased cardiovascular (CVD) risk. Patients with diabetes have decreased number of circulating EPCs and decreased EPC function. This may account for some of the increased CVD risk seen in patients with diabetes that is not explained by traditional risk factors such as glycemic control, dyslipidemia and hypertension. Recent studies seem to indicate that drugs commonly used in diabetes patients such as metformin, thiazolidinediones, GLP-1 agonists, DPP-4 inhibitors, insulin, statins and ACE inhibitors may increase EPC number and improve EPC function. The mechanisms by which these drugs modulate EPC function may involve reduction in inflammation, oxidative stress and insulin resistance as well as an increase in nitric oxide (NO) bioavailability. This review will discuss the evidence in the literature regarding the above mentioned topics.

VEGF levels in plasma in relation to platelet activation, glycemic control, and microvascular complications in type 1 diabetes

OBJECTIVE

Increased levels of vascular endothelial growth factor (VEGF) in human plasma samples have suggested that circulating VEGF is a cause of endothelial dysfunction in diabetes mellitus. However, artificial release of VEGF from platelets as a source of VEGF in plasma samples, as also occurs in serum samples, has not been ruled out in these studies.

RESEARCH DESIGN AND METHODS

We determined VEGF levels in plasma collected in both citrate and PECT, a medium that inactivates platelets, in a cross-sectional cohort of 21 healthy subjects and 64 patients with type 1 diabetes. In addition, we evaluated whether VEGF levels in both types of plasma correlated with the presence of diabetes, glycemic control, markers of in vivo or ex vivo platelet activation, and degree of diabetic retinopathy and nephropathy.

RESULTS

VEGF levels were invariably low in PECT plasma of both nondiabetic and diabetic subjects and were unrelated to any other diabetes-related variable studied. In contrast, VEGF levels in citrate plasma were 150% higher in diabetic patients than in control subjects and correlated with diabetes-related variables. Multiple linear regression analysis showed that levels of platelet factor 4, a marker for ex vivo platelet activation, and HbA1c were the independent predictors of VEGF levels in citrate plasma. Platelet activation, in vivo and ex vivo, was similar in diabetic persons and control subjects.

CONCLUSIONS

Like serum, citrate plasma is not suitable for reliable measurements of circulating VEGF. The low levels of VEGF in vivo, as represented by measurements in PECT plasma in our study, do not support a role of circulating VEGF in endothelial dysfunction in type 1 diabetes. Higher levels of VEGF in citrate plasma samples of diabetic persons do not represent the in vivo situation, but mainly originate from higher artificial ex vivo release from platelets correlating with the degree of glycemic control.

Atorvastatin-induced increase in progenitor cell levels is rather caused by enhanced receptor activator of NF-kappaB ligand (RANKL) cell proliferation than by bone marrow mobilization

BACKGROUND

Statins have been shown to increase the level of circulating progenitor cells in peripheral blood supposedly due to a mobilization of progenitor cells from the bone marrow niche. Osteoclast/osteoblast interaction has been associated with progenitor cell mobilization. Here, we investigated the role of statins on progenitor cell mobilization with a focus on bone metabolism.

METHODS AND RESULTS

FGF2(-/-) and wild type (wt) mice were treated with atorvastatin or placebo. In contrast to wt mice, the number of sca-1/flk-1 positive progenitor cells in peripheral blood (PB) of atorvastatin treated FGF2(-/-) mice did not increase, and was accompanied by a defective reendothelialization after perielectric injury of the common carotid artery. In wt, but not FGF2(-/-) mice, statin treatment was associated with increased levels of receptor activator of NF-κB ligand (RANKL) in bone marrow (BM) supernatant. Treatment with recombinant RANKL increased sca-1/flk-1 positive progenitors in FGF2(-/-) mice. Interestingly, osteoclast activation was not altered. To measure the egress of sca-1/flk-1 positive progenitor cells from the bone marrow, we performed in-situ perfusion experiments of isolated hind limbs. Mobilization was not significantly affected by atorvastatin in both wt and FGF2(-/-) mice. Furthermore, RANK - the specific receptor to RANKL - is expressed on progenitor cells, and RANKL stimulation increases cell proliferation in vitro and in vivo.

CONCLUSIONS

Atorvastatin treatment increases RANKL levels with no measurable effect on bone metabolism and mobilization of progenitor cells from BM to PB. RANKL is essential for the statin-mediated increase of progenitor cell levels but predominantly due to a RANKL-induced stimulation of cell proliferation.

Endothelial cell-selective adhesion molecule in diabetic nephropathy

BACKGROUND

Endothelial cell-selective adhesion molecule (ESAM) contributes to the integrity of tight junctions and modulates endothelial function. ESAM has been linked to experimental diabetic nephropathy; its soluble fraction is related to atherosclerosis in humans. In this cross-sectional observational study, we describe for the first time serum ESAM in type 2 diabetic patients with different stages of chronic kidney disease (CKD) and its relationship to vascular endothelial growth factor-A (VEGF-A). Materials and methods  We included diabetic patients with different stages of CKD and controls. History, laboratory evaluation, serum ESAM and VEGF-A and urinary albumin/creatinine ratio were obtained.

RESULTS

Endothelial cell-selective adhesion molecule was higher in non-CKD diabetic patients 13.80 (6.15-18.70) ng/mL (n=45) than controls 7.30 (4.60-9.40) ng/mL (n=48), P=0.001. VEGF-A had a similar pattern: 71.3 (54.75-120.70) vs. 43.20 (30.1-65.90) pg/mL, P<0.0001. ESAM was 10.4 (5.6-17.4) ng/mL in predialysis CKD patients (n=59) and 22.35 (8.55-29.95) ng/mL in dialysis patients (n=36), P<0.001. Patients with glomerular filtration rate (GFR)<15 mL/min had the highest ESAM (P=0.003). ESAM was similar in normoalbuminuric, microalbuminuric and proteinuric patients. ESAM was directly correlated with the duration of diabetes (r(2)=0.048, P=0.009), C-reactive protein (r(2)=0.028, P=0.05), VEGF-A (r(2)=0.040, P=0.01) and inversely with HbA1C (r(2)=0.036, P=0.03), haemoglobin (r(2)=0.062, P=0.005) and albumin (r(2)=0.0·40, P=0.026). In multiple regression diabetes duration, HbA1C and VEGF-A were significant predictors of ESAM. In controls, ESAM was inversely related to VEGF (r(2)=037, P=0.01).

CONCLUSION

Endothelial cell-selective adhesion molecule and VEGF-A are higher in patients with diabetes than in controls. The highest ESAM is found in dialysis patients. ESAM correlates with diabetes duration and control, inflammation and VEGF-A in patients with diabetes, but not in controls.

Role of simvastatin and/or antioxidant vitamins in therapeutic angiogenesis in experimental diabetic hindlimb ischemia: effects on capillary density, angiogenesis markers, and oxidative stress

Therapeutic angiogenesis has emerged as an attractive approach for the management of peripheral arterial disease in diabetic patients. Oxidative stress generated and aggravated by prolonged hyperglycemia may interfere with and destroy the newly formed blood vessels. Angiogenic effect of simvastatin has been reported; however, its exact mechanism is yet to be evaluated. In addition, the exact role of antioxidant vitamins in diabetic peripheral arterial disease is still controversial. The present study was undertaken to investigate the therapeutic potential of simvastatin and antioxidant vitamins (E and C) and their combined effects on angiogenesis in diabetic hind-limb ischemia. Streptozotocin diabetic rats were treated for 6 weeks with simvastatin either alone or in combination with vitamin E or vitamin C. Parameters of angiogenesis, nitric oxide, heme oxygenase-1 (HO-1), and oxidative stress markers were evaluated. CD31 immunostaining revealed an increased capillary density in ischemic gastrocnemious tissue of diabetic rats treated with either simvastatin or its combination with vitamin C. This effect was accompanied by up-regulated plasma levels of HO-1, nitric oxide, vascular endothelial growth factor (VEGF) and its intra-muscular receptor type-2 (Flk-1). Tissue reduced glutathione and antioxidant enzymes activities were normalized in groups treated with antioxidant vitamins or their combination with simvastatin with concomitant blunting of lipid peroxidation. Vitamins E and C, through their antioxidant effects, evidently enhanced the angiogenic effect of simvastatin in ischemic diabetic muscle. Hence, the use of antioxidant vitamins combined with statins to induce therapeutic angiogenesis is a promising strategy in the management of diabetes-associated peripheral arterial disease.

Endothelial progenitor cells and circulating endothelial cells in early prostate cancer: a comparison with plasma vascular markers

BACKGROUND

Separate studies indicate that endothelial perturbation, as demonstrated by abnormal endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and plasma markers such as von Willebrand factor (vWf) and soluble E selectin (sEsel) are present in cancer. However, there are no reports where these indices are compared. Accordingly, we hypothesized altered EPCs and CECs in prostate cancer that would correlate with vWf, sEsel, and prostate specific antigen (PSA).

METHODS

We recruited 29 men with biopsy proven prostate cancer, with 25 with benign prostate disease and 27 free of prostate disease. CECs were defined on flow cytometry as being CD34+, CD146+, CD45-, and CD309-, EPCs were similarly defined as being CD34+, CD309+,CD45-, and CD146-. vWf, sEsel, and PSA were measured by immunoassay.

RESULTS

Despite higher PSA, sE-sel, and vWf in prostate cancer (all P < 0.02), neither EPCs, CECs, nor their ratio, were significantly different. EPCs and CECs correlated significantly with each other in each group (r > 0.48, P < 0.01) but failed to correlate with any plasma marker.

CONCLUSION

Unlike plasma endothelial markers, CECs and EPCs may play little part in the pathophysiology of early prostate cancer.

Simvastatin augments the efficacy of therapeutic angiogenesis induced by bone marrow-derived mesenchymal stem cells in a murine model of hindlimb ischemia

Many studies showed beneficial effects of either statin or bone marrow-derived mesenchymal stem cells (MSC) treatment in ischemic disease. In an attempt to further improve postischemic tissue repair, we investigated the effect of a local administration of MSC, in the presence or not of low-dose simvastatin, on angiogenesis and functional recovery in a mouse model of hindlimb ischemia. In vitro, the proliferation, migration, apoptosis, and tube formation of bone marrow MSC derived from transgenic mice expressing green fluorescent protein (GFP) were detected in the presence or not of 0.01 μmol/l simvastatin, respectively. In vivo, immediately after hindlimb ischemia, the mice were divided into four groups, namely control, MSC, statin, and statin-MSC, and received a single local injection of MSC (2×10(6) cells) and/or a repeated gavages' administration of simvastatin (0.2 mg/kg) for 21 days. The blood flow was measured by laser Doppler imaging, the capillary density was detected by alkaline phosphatase staining and, the MSC differentiation was assessed by immunofluorescent staining at 21 days after the ischemia. In vitro, the MSC proliferation rate, migration ability and tube formation number were increased significantly in simvastatin group relative to control group. Whereas, the H2O2 induced-apoptosis was inhibited significantly in simvastatin group relative to control group. In vivo, hindlimb blood reperfusion was significantly improved (MSC 0.55±0.08, statin 0.57±0.05, vs. control 0.47±0.07, P<0.05) and capillary density was obviously higher at day 21 post-ischemia by Laser Doppler Imaging in the MSC group and the Statin group when compared with control group. The combined use of statin and MSC further improved revascularization (perfusion ratio of 0.70±0.09; P<0.001 verse other groups) and resulted in the highest capillary density (P<0.05 vs. all other groups). GFP-labeled transplanted cells were more frequently observed in the Statin-MSC group than in the MSC group (6.8±0.5-3.1±0.7, P<0.05). Low-dose simvastatin could act in a synergistic way with MSC to potentiate the functional neovascularization in a mouse model of hind limb ischemia.

Targeting stem cell niches and trafficking for cardiovascular therapy

Regenerative cardiovascular medicine is the frontline of 21st-century health care. Cell therapy trials using bone marrow progenitor cells documented that the approach is feasible, safe and potentially beneficial in patients with ischemic disease. However, cardiovascular prevention and rehabilitation strategies should aim to conserve the pristine healing capacity of a healthy organism as well as reactivate it under disease conditions. This requires an increased understanding of stem cell microenvironment and trafficking mechanisms. Engagement and disengagement of stem cells of the osteoblastic niche is a dynamic process, finely tuned to allow low amounts of cells move out of the bone marrow and into the circulation on a regular basis. The balance is altered under stress situations, like tissue injury or ischemia, leading to remarkably increased cell egression. Individual populations of circulating progenitor cells could give rise to mature tissue cells (e.g. endothelial cells or cardiomyocytes), while the majority may differentiate to leukocytes, affecting the environment of homing sites in a paracrine way, e.g. promoting endothelial survival, proliferation and function, as well as attenuating or enhancing inflammation. This review focuses on the dynamics of the stem cell niche in healthy and disease conditions and on therapeutic means to direct stem cell/progenitor cell mobilization and recruitment into improved tissue repair.

Current perspective of pathophysiological and interventional effects on endothelial progenitor cell biology: focus on PI3K/AKT/eNOS pathway

For more than a decade, endothelial progenitor cells (EPCs) have been implicated in cardiovascular homeostasis. EPCs are believed to reside within the bone marrow in close contact with surrounding stromal cells, and, under stimulation of pro-inflammatory cytokines, EPCs are mobilized out of the bone marrow. Hereafter circulating EPCs home to peripheral tissues, undergoing further proliferation and differentiation. Under certain pathophysiologic conditions this process seems to be blunted, resulting in a reduced capacity of EPCs to engage in vasculogenesis at sites of endothelial injury or tissue ischemia. In this review, we focus on the effects of traditional cardiovascular risk factors on EPC biology and we explore whether pharmacological, dietary and lifestyle interventions can favorably restore EPC mobilization, differentiation, homing and angiogenic properties. Because the PI3K/Akt/eNOS pathway plays a pivotal role in the process of EPC mobilization, migration and homing, we specifically emphasize the involvement of PI3K, Akt and eNOS in EPC biology under these different (patho)physiologic conditions. (Pre)clinically used drugs or lifestyle interventions that have been shown to ameliorate EPC biology are reviewed. These treatment strategies remain attractive targets to restore the regenerative capacity of EPCs in cardiovascular diseases.