Effects of tumour necrosis factor-alpha on activity and nitric oxide synthase of endothelial progenitor cells from peripheral blood

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.

Origins and functional differences of blood endothelial cells

The interests in blood endothelial cells arise from their therapeutic potential in vascular repair and regeneration. Our understanding of blood endothelial cells that exist in the circulation has been evolving significantly from the original concept of endothelial progenitor cells. Many studies have uncovered heterogeneities of blood endothelial subtypes where some cells express both endothelial and hematopoietic antigens, and others possess either mature or immature endothelial markers. Due to the lack of definitive cell marker identities, there have been momentums in the field to adopt a technical-oriented labeling system based on the cells' involvement in postnatal neovascularization and cell culture derivatives. Our review streamlines nomenclatures for blood endothelial subtypes and standardizes understanding of their functional differences. Broadly, we will discuss about myeloid angiogenic cells (MACs), endothelial colony-forming cells (ECFCs), blood outgrowth endothelial cells (BOECs) and circulating endothelial cells (CECs). The strategic location of blood endothelial cells confers them essential roles in supporting physiological processes. MACs exert angiogenic effects through paracrine mechanisms, while ECFCs are recruited to sites of vascular injury to participate directly in new vessel formation. BOECs are an in vitro derivative of ECFCs. CECs are shed into the bloodstream from damaged vessels, hence reflective of endothelial dysfunction. With clarity on the functional attributes of blood endothelial subtypes, we present recent advances in their applications in disease modelling, along with serving as biomarkers of vascular tissue homeostasis.

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.

A tryptophan metabolite prevents depletion of circulating endothelial progenitor cells in systemic low-grade inflammation

Background

Chronic systemic inflammation reduces the bioavailability of circulating endothelial progenitor cells (EPCs). Indoleamine 2,3-dioxygenase 1 (IDO1), a key enzyme of immune tolerance catalyzing the initial step of tryptophan degradation along the so-called l-kynurenine (l-kyn) pathway, that is induced by inflammatory stimuli and exerts anti-inflammatory effects. A specific relationship between IDO1 activity and circulating EPC numbers has not yet been investigated.

Methods

In this study, circulating EPCs were examined in mice treated with low doses of lipopolysaccharide (LPS) to mimic low-grade inflammation. Moreover, the association between IDO1 activity and circulating EPCs was studied in a cohort of 277 patients with variable systemic low-grade inflammation.

Results

Repeated low doses of LPS caused a decrease in circulating EPCs and l-kyn supplementation, mimicking IDO1 activation, significantly increased EPC numbers under homeostatic conditions preventing EPC decline in low-grade endotoxemia. Accordingly, in patients with variable systemic low-grade inflammation, there was a significant interaction between IDO1 activity and high-sensitivity C-reactive protein (hs-CRP) in predicting circulating EPCs, with high hs-CRP associated with significantly lower EPCs at low IDO1 activity but not at high IDO1 activity.

Interpretation

Overall, these findings demonstrate that systemic low-grade inflammation reduces circulating EPCs. However, high IDO1 activity and l-kyn supplementation limit circulating EPC loss in low-grade inflammation.

The role of VEGF in cancer-induced angiogenesis and research progress of drugs targeting VEGF

Angiogenesis is a double-edged sword; it is a mechanism that defines the boundary between health and disease. In spite of its central role in physiological homeostasis, it provides the oxygen and nutrition needed by tumor cells to proceed from dormancy if pro-angiogenic factors tip the balance in favor of tumor angiogenesis. Among pro-angiogenic factors, vascular endothelial growth factor (VEGF) is a prominent target in therapeutic methods due to its strategic involvement in the formation of anomalous tumor vasculature. In addition, VEGF exhibits immune-regulatory properties which suppress immune cell antitumor activity. VEGF signaling through its receptors is an integral part of tumoral angiogenic approaches. A wide variety of medicines have been designed to target the ligands and receptors of this pro-angiogenic superfamily. Herein, we summarize the direct and indirect molecular mechanisms of VEGF to demonstrate its versatile role in the context of cancer angiogenesis and current transformative VEGF-targeted strategies interfering with tumor growth.

CCL4 Deletion Accelerates Wound Healing by Improving Endothelial Cell Functions in Diabetes Mellitus

Chronic inflammation in diabetes mellitus (DM) is the leading cause of non-healing wounds. Chemokine CC motif ligand 4 (CCL4) is enhanced in the circulation and in the wounds of DM patients. This study aimed to investigate the effect of endogenous CCL4 inhibition on diabetic wound healing. Endothelial progenitor cells (EPCs) and human dermal microvascular endothelial cells (HDMECs) were used. Mice were injected with streptozotocin to generate hyperglycemia. An enhanced CCL4 level as well as decreased tube formation and migration abilities were observed in high-glucose-treated HDMECs and in EPCs from type 2 DM patients. CCL4 inhibition by siRNA restored the damaged cell function by upregulating the Akt/endothelial nitric oxide synthase/vascular endothelial growth factor/stromal cell-derived factor-1α pathways. Wild-type diabetic mice had delayed wound repair, whereas the CCL4-knockout diabetic mice showed an accelerated rate of wound closure. In a Matrigel plug assay, CCL4-knockout diabetic mice showed higher blood vessel and hemoglobin levels. Higher CD31 and Ki67 expression in the wound area and Matrigel plugs was detected in the CCL4-knockout diabetic mice. CCL4-knockout mice had upregulated angiogenic factors and downregulated inflammatory factors. This study might provide the theoretical basis for CCL4 inhibition as a therapeutic option for clinical diabetic wound treatment.

Levels of circulating endothelial progenitor cells inversely correlate with manic and positive symptom severity in patients with bipolar disorder

OBJECTIVES

Patients with bipolar disorder (BPD) are at high risk of cardiovascular diseases (CVDs) that are attributed to endothelial dysfunction. Circulating endothelial progenitor cells (cEPCs) are proposed as indicators of endothelial dysfunction. This study examined the relationship of cEPC numbers with BPD diagnosis and its clinical symptoms in patients with BPD.

METHODS

We recruited 48 patients with BPD and 50 healthy controls (HCs). All the patients had scores of <13 on the Young Mania Rating Scale (YMRS). In addition to the YMRS and Clinical Global Impression for BPD (CGI-BP), bipolar patients were assessed using relevant measurements for their depression, anxiety, general psychopathology, cognitive dysfunction and deficit, somatic symptoms, quality of life, and level of disability. cEPC counts were measured using flow cytometry.

RESULTS

The numbers of immature and mature cEPCs in the bipolar patients did not significantly differ from those in the HCs. After correction for multiple comparisons and controlling for body mass index and smokers, the number of immature cEPCs was observed to be inversely correlated with CGI-BP (corrected p [p_corr ] = .00018) and positive scores in the positive and negative syndrome scale (PANSS-P; p_corr  = .0049). The number of mature cEPCs was inversely correlated with YMRS (p_corr  = .014), CGI-BP (p_corr  = .00022), and PANSS-P (p_corr  = .0049) scores. In multivariate stepwise analysis, numbers of both types of cEPCs were associated with CGI-BP.

CONCLUSIONS

cEPC levels, an indicator of endothelial dysfunction and risk of CVDs, may be associated manic and positive symptom severities in patients with BPD.

The impact of different forms of exercise on circulating endothelial progenitor cells in cardiovascular and metabolic disease

Circulating endothelial progenitor cells (EPCs) contribute to vascular repair and their monitoring could have prognostic clinical value. Exercise is often prescribed for the management of cardiometabolic diseases, however, it is not fully understood how it regulates EPCs.

OBJECTIVES

to systematically examine the acute and chronic effects of different exercise modalities on circulating EPCs in patients with cardiovascular and metabolic disease.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed.

RESULTS

six electronic databases and reference lists of eligible studies were searched to April 2021. Thirty-six trials met the inclusion criteria including 1731 participants. Acute trials: in chronic heart failure (CHF), EPC mobilisation was acutely increased after high intensity interval or moderate intensity continuous exercise training, while findings were inconclusive after a cardiopulmonary cycling exercise test. Maximal exercise tests acutely increased EPCs in ischaemic or revascularized coronary artery disease (CAD) patients. In peripheral arterial disease (PAD), EPC levels increased up to 24 h post-exercise. In patients with compromised metabolic health, EPC mobilisation was blunted after a single exercise session. Chronic trials: in CHF and acute coronary syndrome, moderate intensity continuous protocols, with or without resistance exercise or calisthenics, increased EPCs irrespective of EPC identification phenotype. Findings were equivocal in CAD regardless of exercise mode, while in severe PAD disease EPCs increased. High intensity interval training increased EPCs in hypertensive metabolic syndrome and heart failure reduced ejection fraction.

CONCLUSION

the clinical condition and exercise modality influence the degree of EPC mobilisation and magnitude of EPC increases in the long term.

The impact of different forms of exercise on circulating endothelial progenitor cells in cardiovascular and metabolic disease

Circulating endothelial progenitor cells (EPCs) contribute to vascular repair and their monitoring could have prognostic clinical value. Exercise is often prescribed for the management of cardiometabolic diseases, however, it is not fully understood how it regulates EPCs.

OBJECTIVES

to systematically examine the acute and chronic effects of different exercise modalities on circulating EPCs in patients with cardiovascular and metabolic disease.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed.

RESULTS

six electronic databases and reference lists of eligible studies were searched to April 2021. Thirty-six trials met the inclusion criteria including 1731 participants. Acute trials: in chronic heart failure (CHF), EPC mobilisation was acutely increased after high intensity interval or moderate intensity continuous exercise training, while findings were inconclusive after a cardiopulmonary cycling exercise test. Maximal exercise tests acutely increased EPCs in ischaemic or revascularized coronary artery disease (CAD) patients. In peripheral arterial disease (PAD), EPC levels increased up to 24 h post-exercise. In patients with compromised metabolic health, EPC mobilisation was blunted after a single exercise session. Chronic trials: in CHF and acute coronary syndrome, moderate intensity continuous protocols, with or without resistance exercise or calisthenics, increased EPCs irrespective of EPC identification phenotype. Findings were equivocal in CAD regardless of exercise mode, while in severe PAD disease EPCs increased. High intensity interval training increased EPCs in hypertensive metabolic syndrome and heart failure reduced ejection fraction.

CONCLUSION

the clinical condition and exercise modality influence the degree of EPC mobilisation and magnitude of EPC increases in the long term.

Erythropoietin improves effects of mesenchymal stem cells in an experimental model of sepsis

In the last years several studies have shown that mesenchymal stem cells (MSCs) are able to reduce the systemic inflammatory response and mortality in experimental models of sepsis. As recently found, the surface of MSCs have receptors for erythropoietin (EPO). So we hypothesized that the introduction of EPO together with MSCs may enhance their effect and improve the results of sepsis treatment. Aim: То evaluate morphologic and immunologic effects of combined treatment with EPO and MSC in an experimental LPS sepsis model in rats. Methods: 50 Wistar rats were randomized into 5 groups: Group 1 - the healthy controls, Groups 2-5 were intraperitoneally introduced bacterial LPS 20 mg/kg. Two hours after LPS injection animals received the following intravenous treatments: Group 3 - 4xl05 allogeneic MSCs, Group 4 - 8.5 pg of recombinant EPO-beta, Group 5 - MSCs and EPO in the same doses. Surviving animals were euthanased on the 4th day. The morphological study of the liver, spleen, thymus, lungs, kidney tissues was performed. We analyzed the tissue changes, white blood cells count and serum level of IL-l, IL-2, IL-6, TNF-. Results: Mortality in LPS groups did not differ. The highest white blood cells count was found in the group of combined treatment EPO+MSCs (8.15x106 cells/ml) compared with controls (2,15x10s cells/ml) and LPS controls (6,52x10s cells/ml). There were no differences in levels of TNF-, IL-2 and IL-6 between the groups, but serum IL-1 level in groups 2 and 4 was significantly higher than in treated with MSCs and MSCc + EPO animals. Histologically in the group 5 we observed significantly less leukocyte lung interalveolar septal infiltration and kidney tubular dystrophy. The most significant differences in group LPS + EPO were found in the lymphoid tissue - considerable hyperplasia of spleen white pulp and thymus cortex, whereas in the other groups different degrees of atrophy of the corresponding zones were noted. Conclusions: Combined treatment with EPO and MSCs can reduce acute lung injury and kidney damage, cause hyperplasia of lymphoid tissue and enhance the immune response more than separate treatment in an experimental model of sepsis in rats.

Advances of Endothelial Progenitor Cells in the Development of Depression

Depression is a major psychological disease of human beings. With the severity of depression, it elevates the risk of cardiovascular disease (CVD), especially acute coronary syndrome (ACS), resulting in serious harm to human health. The number of endothelial progenitor cells (EPCs) is closely related to the development of depression. It has been reported that the number of peripheral blood EPCs in patients with depression was reduced. However, effects on the function of EPCs in depression are still unclear. This paper aims to analyze and summarize the research of EPCs in depression, and we envision that EPCs might act as a new target for evaluating the severity of depression and its complications.

Endothelial Progenitor Cells Dysfunctions and Cardiometabolic Disorders: From Mechanisms to Therapeutic Approaches

Metabolic syndrome (MetS) is a cluster of several disorders, such as hypertension, central obesity, dyslipidemia, hyperglycemia, insulin resistance and non-alcoholic fatty liver disease. Despite health policies based on the promotion of physical exercise, the reduction of calorie intake and the consumption of healthy food, there is still a global rise in the incidence and prevalence of MetS in the world. This phenomenon can partly be explained by the fact that adverse events in the perinatal period can increase the susceptibility to develop cardiometabolic diseases in adulthood. Individuals born after intrauterine growth restriction (IUGR) are particularly at risk of developing cardiovascular diseases (CVD) and metabolic disorders later in life. It has been shown that alterations in the structural and functional integrity of the endothelium can lead to the development of cardiometabolic diseases. The endothelial progenitor cells (EPCs) are circulating components of the endothelium playing a major role in vascular homeostasis. An association has been found between the maintenance of endothelial structure and function by EPCs and their ability to differentiate and repair damaged endothelial tissue. In this narrative review, we explore the alterations of EPCs observed in individuals with cardiometabolic disorders, describe some mechanisms related to such dysfunction and propose some therapeutical approaches to reverse the EPCs dysfunction.

Effect of recombinant equine interleukin-1β on function of equine endothelial colony-forming cells in vitro

OBJECTIVE

To investigate the effects of recombinant equine IL-1β on function of equine endothelial colony-forming cells (ECFCs) in vitro.

SAMPLE

ECFCs derived from peripheral blood samples of 3 healthy adult geldings.

PROCEDURES

Function testing was performed to assess in vitro wound healing, tubule formation, cell adhesion, and uptake of 1,1'-dioctadecyl-3,3,3',3' tetramethylindocarbocyanine perchlorate-labeled acetylated low-density lipoprotein (DiI-Ac-LDL) by cultured ECFCs. Cell proliferation was determined by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide assay. Effects on function test results of different concentrations and exposure times of recombinant equine IL-1β were assessed.

RESULTS

Challenge of cultured ECFCs with IL-1β for 48 hours inhibited tubule formation. Continuous challenge (54 hours) with IL-1β in the wound healing assay reduced gap closure. The IL-1β exposure did not significantly affect ECFC adhesion, DiI-Ac-LDL uptake, or ECFC proliferation.

CONCLUSIONS AND CLINICAL RELEVANCE

These results suggested a role for IL-1β in the inhibition of ECFC function in vitro. Functional changes in ECFCs following challenge with IL-1β did not appear to be due to changes in cell proliferative capacity. These findings have implications for designing microenvironments for and optimizing therapeutic effects of ECFCs used to treat ischemic diseases in horses.

CXCL12 in normal and pathological pregnancies: A review

The survival of allogeneic fetuses during pregnancy is a rather paradoxical phenomenon with a complex mechanism. Chemokine ligand12 (CXCL12) and its receptors CXC chemokine receptor (CXCR)4 and 7 are extensively found in placenta tissues and cells, including trophoblast cells, vascular endothelial cells, and decidual stromal and decidual immune cells (eg, NK cells and regulatory T cells). Evidence has illustrated that the CXClL12/CXCR4/CXCR7 axis could enhance the cross talk at the maternal-fetal interface through multiple processes, such as invasion and placental angiogenesis, which appears to be critical signaling components in placentation and fetal outcome. In addition, an increasing number of studies have demonstrated that the CXCL12/CXCR4/CXCR7 axis also stands out for its pleiotropic roles in several pregnancy-associated diseases (eg, recurrent spontaneous abortion (RSA), pre-eclampsia (PE), and preterm labor). In the present review, the different biological properties and signaling in physiological and pathological pregnancy conditions of CXCL12/CXCR4/CXCR7 axis were discussed, with the aim of obtaining a further understanding of the regulatory mechanisms and highlighting their potential as a target for therapeutic approaches.

Elevated GTP Cyclohydrolase I Pathway in Endothelial Progenitor Cells of Overweight Premenopausal Women

Background/Aims. Sexual differences exist in endothelial progenitor cells (EPCs), and various cardiovascular risk factors are associated with the preservation of endothelial function in premenopausal women. However, it is unclear whether differences in endothelial function and circulating EPCs exist between overweight premenopausal women and age-matched men. Methods. We compared EPC counting and functions in normal-weight and overweight premenopausal women and men, evaluated endothelial function in each group, and detected the expression of the guanosine triphosphate cyclohydrolase I (GTPCH I) pathway. Results. The number of EPCs was lower in the male group than in the female group, regardless of normal-weight or overweight status, and there was no significant difference between the different weight groups among females or males. Endothelial function and EPC migration and proliferation were preserved in overweight premenopausal women compared with overweight men as were nitric oxide (NO) levels in plasma and secreted by EPCs. Endothelial function, the circulating EPC population, and NO levels were not different between normal-weight and overweight premenopausal women. Flow-mediated dilatation was significantly correlated with EPC function, plasma NO levels, and EPC-secreted NO. Conclusions. This investigation provides the first evidence for sex-based differences in EPC activity and endothelial function in overweight middle-aged individuals; these differences are associated with alterations in NO production and may partly occur through downregulation of the GTPCH I pathway. The present results provide new insights into the mechanism underlying the preserved endothelial function in overweight premenopausal women and may uncover a potential therapeutic target for endothelial repair in overweight population.

Cys-peptide mediates the protective role in preeclampsia-like rat and cell models

OBJECTIVE

The present study was designed to investigate whether the novel peptide cysteine-based peptide (Cys-peptide) had protective effects on preeclamptic animal and cell models.

METHODS

We investigated effects of Cys-peptide on (1) preeclamptic symptoms (e.g. hypertension, proteinuria, fetal growth restriction (FGR)) in preeclampia-like rat models induced by lipopolysaccharides (LPS), (2) TNFα-induced cytotoxicity of human umbilical vascular endothelial cells (HUVECs) and HTR-8 cells (an immortalised human trophoblast cell line), (3) endothelial dysfunction and injured angiogenesis, (4) migration and invasion of trophoblast cells induced by TNFα.

RESULTS

Cys-peptide ameliorated LPS-induced hypertension, proteinuria and FGR and other PE symptoms in preeclampia-like rat models. In addition, Cys-peptide attenuated TNFα-induced cytotoxicity by decreasing soluble fms-like tyrosine kinase-1 (sFlt-1), endothelin-1 (ET-1) and tissue plasminogen activator (tPA) mRNA expression in both cells. Furthermore, Cys-peptide restored endothelial dysfunction and rescued angiogenesis caused by TNFα in vitro. Importantly, Cys-peptide could reverse insufficient ability to invade and migrate of trophoblast cells.

CONCLUSIONS

These results suggest Cys-peptide can play beneficial roles in preeclampsia-like rat and cell models. Therefore, we propose that Cys-peptide is probably a novel therapeutic candidate for PE.

Dietary Supplemental Glutamine Enhances the Percentage of Circulating Endothelial Progenitor Cells in Mice with High-Fat Diet-Induced Obesity Subjected to Hind Limb Ischemia

This study investigated whether glutamine (GLN) pretreatment can enhance circulating endothelial progenitor cells (EPCs) and attenuate inflammatory reaction in high-fat diet-induced obese mice with limb ischemia. Mice were assigned to a normal control (NC), high-fat control (HC), limb ischemia (HI), and GLN limb ischemia (HG) groups. The NC group provided chow diet and treated as a negative control. Mice in the HC and HI groups were fed a high-fat diet which 60% energy provided by fat for 8 weeks. Mice in the HG group were fed the same diet for 4 weeks and then transferred to a high-fat diet with 25% of total protein nitrogen provided as GLN to replace part of the casein for the subsequent 4 weeks. After feeding 8 weeks, mice in the HC group were sham-operated, while the HI and HG groups underwent an operation to induce limb ischemia. All mice except the NC group were euthanized on either day 1 or 7 after the operation. The results showed that the 8 weeks' high-fat diet feeding resulted in obesity. The HG group had higher circulating EPCs on day 1 while muscle vascular endothelial growth factor, matrix metalloproteinase-9, and hypoxia-inducible factor-1 gene expressions were higher on day 7 postischemia than those of the HI group. The superoxide dismutase activity and reduced glutathione content in affected muscles were higher, whereas mRNA expressions of interleukin-6 and tumor necrosis factor-α were lower in the HG than those in the HI group. These findings suggest that obese mice pretreated with GLN-supplemented high-fat diet increased circulating EPC percentage, enhanced the antioxidant capacity, and attenuated inflammatory reactions in response to limb ischemia.

Rheumatoid arthritis (RA) and cardiovascular disease

Patients with rheumatoid arthritis (RA) suffer cardiovascular events 1.5-2 fold than the general population, and cardiovascular (CV) events are leading cause of death in patients with RA. It is known that patients with RA have endothelial dysfunction, related with impaired function of endothelial progenitor cells (EPCs). The mechanistic pathways leading to endothelial function are complicated, but understanding these mechanisms may open new frontiers of management and therapies to patients suffering from atherosclerosis. Inflammation is a key factor in atherosclerosis, including endothelial function, plaque stabilization and post infarct remodeling; thus, inhibition of TNF-α may affect the inflammatory burden and plaque vulnerability leading to less cardiovascular events and myocardial infarctions. An aggressive management of inflammation may lead to a significant improvement in the clinical cardiovascular outcome of patients with RA. The clinical evidence that showed a reduced risk of CV events following treatment with anti-inflammatory agents may suggest a new approach to treat atherosclerosis, i.e., inhibition of inflammation using biological medications that were primarily aimed to treat the high scale inflammation of RA and other autoimmune-inflammatory diseases, but may be useful also to prevent progression of atherosclerosis.

Dipeptidyl dipeptidase-4 inhibitor recovered ischemia through an increase in vasculogenic endothelial progenitor cells and regeneration-associated cells in diet-induced obese mice

Metabolic syndrome (MS), overlapping type 2 diabetes, hyperlipidemia, and/or hypertension, owing to high-fat diet, poses risk for cardiovascular disease. A critical feature associated with such risk is the functional impairment of endothelial progenitor cells (EPCs). Dipeptidyl dipeptidase-4 inhibitors (DPP-4 i) not only inhibit degradation of incretins to control blood glucose levels, but also improve EPC bioactivity and induce anti-inflammatory effects in tissues. In the present study, we investigated the effects of such an inhibitor, MK-06266, in an ischemia model of MS using diet-induced obese (DIO) mice. EPC bioactivity was examined in MK-0626-administered DIO mice and a non-treated control group, using an EPC colony-forming assay and bone marrow cKit⁺ Sca-1⁺ lineage-cells, and peripheral blood-mononuclear cells. Our results showed that, in vitro, the effect of MK-0626 treatment on EPC bioactivities and differentiation was superior compared to the control. Furthermore, microvascular density and pericyte-recruited arteriole number increased in MK-0626-administered mice, but not in the control group. Lineage profiling of isolated cells from ischemic tissues revealed that MK-0626 administration has an inhibitory effect on unproductive inflammation. This occurred via a decrease in the influx of total blood cells and pro-inflammatory cells such as neutrophils, total macrophages, M1, total T-cells, cytotoxic T-cells, and B-cells, with a concomitant increase in number of regeneration-associated cells, such as M2/M ratio and T_reg/T-helper. Laser Doppler analysis revealed that at day 14 after ischemic injury, blood perfusion in hindlimb was greater in MK-0626-treated DIO mice, but not in control. In conclusion, the DPP-4 i had a positive effect on EPC differentiation in MS model of DIO mice. Following ischemic injury, DPP-4 i sharply reduced recruitment of pro-inflammatory cells into ischemic tissue and triggered regeneration and reparation, making it a promising therapeutic agent for MS treatment.

Diabetic endothelial colony forming cells have the potential for restoration with glycomimetics

Endothelial colony forming progenitor cell (ECFC) function is compromised in diabetes, leading to poor vascular endothelial repair, which contributes to impaired diabetic foot ulcer healing. We have generated novel glycomimetic drugs with protective effects against endothelial dysfunction. We investigated the effect of glycomimetic C3 on the functional capacity of diabetic ECFCs. ECFCs were isolated from healthy controls and patients with diabetes with neuroischaemic (NI) or neuropathic (NP) foot ulcers. Functionally, diabetic ECFCs demonstrated delayed colony formation (p < 0.02), differential proliferative capacity (p < 0.001) and reduced NO bioavailability (NI ECFCs; p < 0.05). Chemokinetic migration and angiogenesis were also reduced in diabetic ECFCs (p < 0.01 and p < 0.001), and defects in wound closure and tube formation were apparent in NP ECFCs (p < 0.01). Differential patterns in mitochondrial activity were pronounced, with raised activity in NI and depressed activity in NP cells (p < 0.05). The application of glycomimetic improved scratch wound closure in vitro in patient ECFCs (p < 0.01), most significantly in NI cells (p < 0.001), where tube formation (p < 0.05) was also improved. We demonstrate restoration of the deficits in NI cells but not NP cells, using a novel glycomimetic agent, which may be advantageous for therapeutic cell transplantation or as a localised treatment for NI but not NP patients.

Blood Outgrowth and Proliferation of Endothelial Colony Forming Cells are Related to Markers of Disease Severity in Patients with Pulmonary Arterial Hypertension

In pulmonary arterial hypertension (PAH), lung-angioproliferation leads to increased pulmonary vascular resistance, while simultaneous myocardial microvessel loss contributes to right ventricular (RV) failure. Endothelial colony forming cells (ECFC) are highly proliferative, angiogenic cells that may contribute to either pulmonary vascular obstruction or to RV microvascular adaptation. We hypothesize ECFC phenotypes (outgrowth, proliferation, tube formation) are related to markers of disease severity in a prospective cohort-study of 33 PAH and 30 healthy subjects. ECFC were transplanted in pulmonary trunk banded rats with RV failure. The presence of ECFC outgrowth in PAH patients was associated with low RV ejection fraction, low central venous saturation and a shorter time to clinical worsening (5.4 months (0.6–29.2) vs. 36.5 months (7.4–63.4), p = 0.032). Functionally, PAH ECFC had higher proliferative rates compared to control in vitro, although inter-patient variability was high. ECFC proliferation was inversely related to RV end diastolic volume (R² = 0.39, p = 0.018), but not pulmonary vascular resistance. Tube formation-ability was similar among donors. Normal and highly proliferative PAH ECFC were transplanted in pulmonary trunk banded rats. While no effect on hemodynamic measurements was observed, RV vascular density was restored. In conclusion, we found that ECFC outgrowth associates with high clinical severity in PAH, suggesting recruitment. Transplantation of highly proliferative ECFC restored myocardial vascular density in pulmonary trunk banded rats, while RV functional improvements were not observed.

Endothelial Progenitor Cells: New Targets for Therapeutics for Inflammatory Conditions With High Cardiovascular Risk

Over the past decade, we have witnessed an exponential growth of interest into the role of endothelial progenitor cells (EPCs) in cardiovascular disease. While the major thinking revolves around EPC angiogenic repair properties, we have used a hypothesis-driven approach to discover disease-related defects in their characteristics and based on these findings, have identified opportunities for functional enhancement, which offer an exciting avenue for translation into clinical intervention. In this review, we focus on two groups; circulating myeloid angiogenic cells (MACs) and late outgrowth endothelial colony forming cells (ECFCs), and will discuss the unique properties and defects of each population, as new insights have been gained into the potential function of each sub-type using current techniques and multiomic technology. We will discuss their role in inflammatory disorders and alterations in mitochondrial function. In addition, we share key insights into the glycocalyx, and propose this network of membrane-bound proteoglycans and glycoproteins, covering the endothelium warrants further investigation in order to clarify its significance in ECFC regulation of vascularization and angiogenesis and ultimately for potential translational therapeutic aspects.

Endothelial Progenitor Cells in Heart Failure: an Authentic Expectation for Potential Future Use and a Lack of Universal Definition

Congestive heart failure (CHF) is a prevalent disease (especially among the elderly) with high mortality and morbidity rates. The pathological hallmark of CHF is a loss of cardiomyocytes leading to cardiac fibrosis and dysfunctional cardiac remodeling, which culminates in organ failure. Endothelial progenitor cells (EPCs) are bone marrow-derived cells that contribute to maintenance of the integrity of endothelial wall and protect ischemic myocardium through forming new blood vessels (vasculogenesis) or proliferation of pre-existing vasculature (angiogenesis). Despite its potential, little is known about EPCs and their function in CHF. Here, we define EPC and its role in health and CHF, highlighting their contributions as a cornerstone in the maintenance of a healthy endothelium. Thereafter, we explore the behavior and relevance of EPCs in the pathophysiology of CHF, their prognostic importance, and possible utilization of EPCs as therapy for CHF. Lastly, the restrictions surrounding the use of EPCs in clinical practice will be discussed.

Decreased Count and Dysfunction of Circulating EPCs in Postmenopausal Hypercholesterolemic Females via Reducing NO Production

Endothelial progenitor cells (EPCs) contribute to the endogenous endothelial repair program during hypercholesterolemia. EPC count and migratory and proliferative capacities remain unchanged in the premenopausal female with hypercholesterolemia. However, the changes of count and activity of circulating EPCs in the hypercholesterolemic postmenopausal females are unknown. Here, we find that the migratory and proliferative capacities of circulating EPCs were decreased in patients with hypercholesterolemia versus normocholesterolemia. No significant differences were found between postmenopausal females and age-matched males. NO production showed positive correlation with the activity and count of circulating EPCs in patients with hypercholesterolemia. Flow-mediated dilatation (FMD) is directly interrelated with EPC counts and function. Our findings reveal that decreased EPC count and endothelial dysfunction lead to less NO production in hypercholesterolemic postmenopausal females. Maintaining the EPC numbers and activity might be emerging as a potential therapeutic strategy to reduce the risk of cardiovascular injury in elder women.

Acidic preconditioning of endothelial colony-forming cells (ECFC) promote vasculogenesis under proinflammatory and high glucose conditions in vitro and in vivo

Background

We have previously demonstrated that acidic preconditioning of human endothelial colony-forming cells (ECFC) increased proliferation, migration, and tubulogenesis in vitro, and increased their regenerative potential in a murine model of hind limb ischemia without baseline disease. We now analyze whether this strategy is also effective under adverse conditions for vasculogenesis, such as the presence of ischemia-related toxic molecules or diabetes, one of the main target diseases for cell therapy due to their well-known healing impairments.

Methods

Cord blood-derived CD34⁺ cells were seeded in endothelial growth culture medium (EGM2) and ECFC colonies were obtained after 14–21 days. ECFC were exposed at pH 6.6 (preconditioned) or pH 7.4 (nonpreconditioned) for 6 h, and then pH was restored at 7.4. A model of type 2 diabetes induced by a high-fat and high-sucrose diet was developed in nude mice and hind limb ischemia was induced in these animals by femoral artery ligation. A P value < 0.05 was considered statistically significant (by one-way analysis of variance).

Results

We found that acidic preconditioning increased ECFC adhesion and the release of pro-angiogenic molecules, and protected ECFC from the cytotoxic effects of monosodium urate crystals, histones, and tumor necrosis factor (TNF)α, which induced necrosis, pyroptosis, and apoptosis, respectively. Noncytotoxic concentrations of high glucose, TNFα, or their combination reduced ECFC proliferation, stromal cell-derived factor (SDF)1-driven migration, and tubule formation on a basement membrane matrix, whereas almost no inhibition was observed in preconditioned ECFC. In type 2 diabetic mice, intravenous administration of preconditioned ECFC significantly induced blood flow recovery at the ischemic limb as measured by Doppler, compared with the phosphate-buffered saline (PBS) and nonpreconditioned ECFC groups. Moreover, the histologic analysis of gastrocnemius muscles showed an increased vascular density and reduced signs of inflammation in the animals receiving preconditioned ECFC.

Conclusions

Acidic preconditioning improved ECFC survival and angiogenic activity in the presence of proinflammatory and damage signals present in the ischemic milieu, even under high glucose conditions, and increased their therapeutic potential for postischemia tissue regeneration in a murine model of type 2 diabetes. Collectively, our data suggest that acidic preconditioning of ECFC is a simple and inexpensive strategy to improve the effectiveness of cell transplantation in diabetes, where tissue repair is highly compromised.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0872-7) contains supplementary material, which is available to authorized users.

Arginine pretreatment enhances circulating endothelial progenitor cell population and attenuates inflammatory response in high-fat diet-induced obese mice with limb ischemia

Obesity is a global health problem with an up-regulated inflammatory reaction. Obesity-induced endothelial progenitor cells (EPCs) dysfunction is associated with vascular complications that may contribute to critical limb ischemia. Arginine (Arg) is an amino acid with immune-modulatory property and has been found to promote EPCs mobilization in disease conditions. Thus in the present investigation, we hypothesized that arginine given to a murine model of diet-induced obesity would increase circulating EPCs and mitigate the inflammatory reactions in response to limb ischemia. Mice were divided into normal group (NC), high-fat group (HC), and high-fat Arg group (HA). Mice in the HC group were fed with a diet containing 60% energy as fat for 8 weeks, while HA group were initially fed with the same high-fat diet for 4 weeks and later shifted to a high-fat diet enriched with 2% Arg for the remaining 4 weeks. Then mice in the HC and HA groups underwent ischemic operations and were euthanized at either day 1 or day 7 after limb ischemia. The results showed that, compared to the ischemic HC group, the ischemic HA group had higher circulating EPCs at day 1 post-ischemia and higher muscle stromal cell-derived factor-1 and interleukin (IL)-10 mRNA expressions at day 7 after ischemia. In contrast, plasma leptin concentration and expressions of IL-1β and tumor necrosis factor-α mRNAs by adipocytes were down-regulated. These findings suggest that obese mice treated with Arg-containing high-fat diet enhanced circulating EPCs percentage and attenuated inflammatory reaction in response to limb ischemia.

Glutamine Administration Modulates Endothelial Progenitor Cell and Lung Injury in Septic Mice

This study investigated the effects of glutamine (GLN) administration on circulating endothelial progenitor cells (EPCs) and lung angiopoietin (Ang) gene expressions in polymicrobial sepsis. Mice were randomly assigned to a normal control group (NC), septic saline group (SS), and septic GLN group (SG). All mice were fed with a chow diet. Sepsis was induced by cecal ligation and puncture (CLP). The mice in SS group were injected with saline, whereas SG group administered 0.75 g GLN/kg body weight once via tail vein 1 h after CLP. Mice were killed 24 and 48 h after CLP. Their blood and lungs were collected for further analysis. The results showed that, compared with normal mice, sepsis resulted in higher C-X-C motif chemokine-12, vascular endothelial growth factor, nitric oxide levels, and a higher circulating EPC percentage. In addition, inflammatory cytokine concentrations and Ang-2 gene expression were upregulated in lung tissues. GLN administration enhanced the mobilization of EPC, and downregulated inflammatory cytokine production and the Ang-2 gene expressions in lungs. Histopathological findings showed that the extent of inflammatory lesions of the lung alveolar was less severe in the SG group than the SS group after CLP. Our results suggest that a single dose of intravenous GLN administration after initiation of sepsis promotes the mobilization of circulating EPC, and modulates the balance of Ang-Tie2 axis that may improve the vascular function, ameliorate inflammation, and protect lung injury against polymicrobial sepsis.

Cellular mechanisms underlying cardiac engraftment of stem cells

INTRODUCTION

Over the past decade, it has become clear that long-term engraftment of any ex vivo expanded cell product transplanted into injured myocardium is modest and all therapeutic regeneration is mediated by stimulation of endogenous repair rather than differentiation of transplanted cells into working myocardium. Given that increasing the retention of transplanted cells boosts myocardial function, focus on the fundamental mechanisms limiting retention and survival of transplanted cells may enable strategies to help to restore normal cardiac function. Areas covered: This review outlines the challenges confronting cardiac engraftment of ex vivo expanded cells and explores means of enhancing cell-mediated repair of injured myocardium. Expert opinion: Stem cell therapy has already come a long way in terms of regenerating damaged hearts though the poor retention of transplanted cells limits the full potential of truly cardiotrophic cell products. Multifaceted strategies directed towards fundamental mechanisms limiting the long-term survival of transplanted cells will be needed to enhance transplanted cell retention and cell-mediated repair of damaged myocardium for cardiac cell therapy to reach its full potential.

Intravenous Arginine Administration Promotes Proangiogenic Cells Mobilization and Attenuates Lung Injury in Mice with Polymicrobial Sepsis

This study investigated the influence of intravenous arginine (Arg) administration on alteration of circulating proangiogenic cells and remote lung injury in a model of polymicrobial sepsis. Mice were assigned to one normal control group (NC) and two sepsis groups that were induced by cecal ligation and puncture (CLP). One of the sepsis groups was injected with saline (SS), whereas the other (SA) was administered with a single bolus of 300 mg Arg/kg body weight via the tail vein 1 h after CLP. Septic mice were sacrificed at either 24 or 48 h after CLP, with their blood and lung tissues collected for analysis. Results showed that septic groups had higher proangiogenic cells releasing factors and proangiogenic cells percentage in blood. Also, concentration of inflammatory cytokines and expression of angiopoietin (Angpt)/Tie-2 genes in lung tissues were upregulated. Arg administration promoted mobilization of circulating proangiogenic cells while it downregulated the production of inflammatory cytokines and expression of Angpt/Tie-2 genes in the lung. The results of this investigation suggested that intravenous administration of Arg shortly after the onset of sepsis enhanced the mobilization of circulating proangiogenic cells, maintained the homeostasis of the Angpt/Tie-2 axis, and attenuated remote organ injury in polymicrobial sepsis.

Disrupting Tumor Angiogenesis and "the Hunger Games" for Breast Cancer

Angiogenesis, one of the hallmarks of cancers, has become an attractive target for cancer therapy since decades ago. It is broadly thought that upregulation of angiogenesis is involved in tumor progression and metastasis. Though tumor vessels are tortuous, disorganized, and leaky, they deliver oxygen and nutrients for tumor development. Based on this knowledge, many kinds of drugs targeting angiogenesis pathways have been developed, such as bevacizumab. However, the clinical outcomes of anti-angiogenesis therapies are moderate in metastatic breast cancer as well as in metastatic colorectal cancer and non-small cell lung cancer, even combined with traditional chemotherapy. In this chapter, the morphologic angiogenesis patterns and the key molecular pathways regulating angiogenesis are elaborated. The FDA-approved anti-angiogenesis drugs and current challenges of anti-angiogenesis therapy are described. The strategies to overcome the barriers will also be elucidated.

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

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

Number of colony-forming unit-Hill colonies among children and teenagers with obesity, dyslipidemia and breastfeeding history

BACKGROUND AND AIMS

The number of colony-forming unit (CFU)-Hill colonies has been proposed as a biomarker of vascular function and cardiovascular risk in adults but information about its role in children is scarce. This study evaluates the associations between obesity, cardiovascular risk factors and breastfeeding history with the numbers of CFU-Hill colonies in a sample of young people.

METHODS AND RESULTS

We selected 49 children and teenagers between ages 10 and 17 (65.3% boys) from Mexican Health Care system. Physical activity and Anthropometric measures data were registered. CFU-Hill colonies were cultured from mononuclear cells obtained from venous blood. We detected inverse associations between the formation of CFU-Hill colonies and body mass index (BMI; β = -1.53; 95% confidence interval [CI], -1.92, -1.13), triglycerides (β = -0.26; 95%CI = -0.34, -0.18), total cholesterol (β = -0.13; 95%CI = -0.17, -0.08), Low Density Lipoprotein (LDL) (β = -0.20; 95%CI = -0.31, -0.09) and glucose (β = -0.37; 95%CI = -0.55, -0.18) using multivariate models. Breastfeeding duration showed a 1.46-colony increase for each month of breastfeeding (95%CI = 0.73, 2.18).

CONCLUSIONS

CFU-Hill colony-forming capacity in children and teenagers was inversely associated with obesity, dyslipidemia and high blood levels of glucose. In contrast a longer breastfeeding duration was directly associated with an increased number of CFU-Hill colonies. However these results must be confirmed with further studies. Our findings support the importance of promoting breastfeeding and monitoring nutritional and metabolic status at an early age to prevent chronic disease development.

Significance and therapeutic implications of endothelial progenitor cells in angiogenic-mediated tumour metastasis

Cancer conveys profound social and economic consequences throughout the world. Metastasis is responsible for approximately 90% of cancer-associated mortality and, when it occurs, cancer becomes almost incurable. During metastatic dissemination, cancer cells pass through a series of complex steps including the establishment of tumour-associated angiogenesis. The human endothelial progenitor cells (hEPCs) are a cell population derived from the bone marrow which are required for endothelial tubulogenesis and neovascularization. They also express abundant inflammatory cytokines and paracrine angiogenic factors. Clinically hEPCs are highly correlated with relapse, disease progression, metastasis and treatment response in malignancies such as breast cancer, ovarian cancer and non-small-cell lung carcinoma. It has become evident that the hEPCs are involved in the angiogenesis-required progression and metastasis of tumours. However, it is not clear in what way the signalling pathways, controlling the normal cellular function of human BM-derived EPCs, are hijacked by aggressive tumour cells to facilitate tumour metastasis. In addition, the actual roles of hEPCs in tumour angiogenesis-mediated metastasis are not well characterised. In this paper we reviewed the clinical relevance of the hEPCs with cancer diagnosis, progression and prognosis. We further summarised the effects of tumour microenvironment on the hEPCs and underlying mechanisms. We also hypothesized the roles of altered hEPCs in tumour angiogenesis and metastasis. We hope this review may enhance our understanding of the interaction between hEPCs and tumour cells thus aiding the development of cellular-targeted anti-tumour therapies.

Glucose and acute exercise influence factors secreted by circulating angiogenic cells in vitro

Circulating angiogenic cells (CAC) influence vascular repair through the secretion of proangiogenic factors and cytokines. While CAC are deficient in patients with diabetes and exercise has a beneficial effect on CACs, the impact of these factors on paracrine secretion from CAC is unknown. We aimed to determine whether the in vitro secretion of selected cytokines and nitric oxide (NO) from CAC is influenced by hyperglycemia and acute exercise. Colony‐forming unit CAC (CFU‐CAC) were cultured from young active men (n = 9, 24 ± 2 years) at rest and after exercise under normal (5 mmol/L) and elevated (15 mmol/L) glucose. Preliminary relative multiplex cytokine analysis revealed that CAC conditioned culture media contained three of six measured cytokines: transforming growth factor‐beta‐1 (TGFβ1), tumor necrosis factor alpha (TNFα), and monocyte chemotactic protein‐1 (MCP‐1). Single quantitative cytokine analysis was used to determine the concentration of each cytokine from the four conditions. NO was measured via Griess assay. There was a significant effect of CAC exposure to in vivo exercise on in vitro TGFβ1 secretion (P = 0.024) that was independent of glucose concentration. There was no effect of glucose or acute exercise on TNFα or MCP‐1 concentration (both P > 0.05). The concentration of NO from CFU‐CAC cultured in elevated glucose was lower following acute exercise (P = 0.002) suggesting that exercise did not maintain NO secretion under hyperglycemic conditions. Our results identify paracrine signaling factors that may be responsible for the proangiogenic function of CFU‐CAC and an influence of acute exercise and elevated glucose on CFU‐CAC soluble factor secretion.

Insights into the molecular mechanisms of diabetes-induced endothelial dysfunction: focus on oxidative stress and endothelial progenitor cells

Diabetes mellitus is a heterogeneous, multifactorial, chronic disease characterized by hyperglycemia owing to insulin insufficiency and insulin resistance (IR). Recent epidemiological studies showed that the diabetes epidemic affects 382 million people worldwide in 2013, and this figure is expected to be 600 million people by 2035. Diabetes is associated with microvascular and macrovascular complications resulting in accelerated endothelial dysfunction (ED), atherosclerosis, and cardiovascular disease (CVD). Unfortunately, the complex pathophysiology of diabetic cardiovascular damage is not fully understood. Therefore, there is a clear need to better understand the molecular pathophysiology of ED in diabetes, and consequently, better treatment options and novel efficacious therapies could be identified. In the light of recent extensive research, we re-investigate the association between diabetes-associated metabolic disturbances (IR, subclinical inflammation, dyslipidemia, hyperglycemia, dysregulated production of adipokines, defective incretin and gut hormones production/action, and oxidative stress) and ED, focusing on oxidative stress and endothelial progenitor cells (EPCs). In addition, we re-emphasize that oxidative stress is the final common pathway that transduces signals from other conditions-either directly or indirectly-leading to ED and CVD.

Reverse-D-4F Increases the Number of Endothelial Progenitor Cells and Improves Endothelial Progenitor Cell Dysfunctions in High Fat Diet Mice

Although high density lipoprotein (HDL) improves the functions of endothelial progenitor cells (EPCs), the effect of HDL ApoAI mimetic peptide reverse-D-4F (Rev-D4F) on EPC mobilization and repair of EPC dysfunctions remains to be studied. In this study, we investigated the effects of Rev-D4F on peripheral blood cell subpopulations in C57 mice treated with a high fat diet and the mechanism of Rev-D4F in improving the function of EPCs impaired by tumor necrosis factor-α (TNF-α). The high fat diet significantly decreased the number of EPCs, EPC migratory functions, and the percentage of lymphocytes in the white blood cells. However, it significantly increased the number of white blood cells, the percentage of monocytes in the white blood cells, and the level of vascular endothelial growth factor (VEGF) and TNF-α in the plasma. Rev-D4F clearly inhibited the effect of the high fat diet on the quantification of peripheral blood cell subpopulations and cytokine levels, and increased stromal cell derived factor 1α (SDF-1α) in the plasma. We provided in vitro evidence that TNF-α impaired EPC proliferation, migration, and tube formation through inactive AKT and eNOS, which was restored by Rev-D4F treatment. In contrast, both the PI3-kinase (PI3K) inhibitor (LY294002) and AKT inhibitor (perifosine) obviously inhibited the restoration of Rev-4F on EPCs impaired by TNF-α. Our results suggested that Rev-D4F increases the quantity of endothelial progenitor cells through increasing the SDF-1α levels and decreasing the TNF-α level of peripheral blood in high fat diet-induced C57BL/6J mice, and restores TNF-α induced dysfunctions of EPCs partly through stimulating the PI3K/AKT signal pathway.

Insights into the mechanism of CXCL12-mediated signaling in trophoblast functions and placental angiogenesis

The chemokine CXCL12 and its receptor CXCR4 are important signaling components required for human blastocyst implantation and the progression of pregnancy. Growing evidence indicates that the CXCL12/CXCR4 axis can regulate trophoblast function and uterine spiral artery remodeling, which plays a fundamental role in placentation and fetal outcome. The orphan receptor CXCR7 is also believed to partly regulate the function of the CXCL12/CXCR4 axis. Additionally, the CXCL12/CXCR4/CXCR7 axis can enhance the cross-talk between trophoblasts and decidual cells such as uterine natural killer cells and decidual stromal cells which are involved in regulation of trophoblast differentiation and invasion and placental angiogenesis. In addition, recent studies proved that CXCL12 expression is elevated in the placenta and mid-trimester amniotic fluid of pregnant women with preeclampsia, implying that dysregulation of CXCL12 plays a role in the pathogenesis of preeclampsia. Further understanding of the regulatory mechanisms of CXCL12-mediated signaling in trophoblast functions and placental angiogenesis may help to design novel therapeutic approaches for pregnancy-associated diseases.

The protective effect of astragaloside IV against benzo[a]pyrene induced endothelial progenitor cell dysfunction

AIMS

Benzo[a]pyrene (BaP), a prominent component of tobacco, has been revealed to induce damage to endothelial progenitor cells (EPCs). Astragaloside IV (AS-IV) is widely used for the treatment of cardiovascular diseases in China. In this study, we evaluated the effects of AS-IV on the function of human EPCs after BaP exposure and explored the underlying mechanism.

MATERIALS AND METHODS

Human umbilical cord blood mononuclear cells were isolated using density gradient centrifugation. Cells of the 4th passage were randomly divided into 6 groups. EPCs of experimental groups were pre-treated with different concentrations (2, 10 and 50 μg/mL) of AS-IV for 2h before exposure to BaP (20 μM) for 24h. The proliferation, migration, and adhesion of the treated EPCs were evaluated using a cell counting kit-8, Transwell assay and adhesion assay respectively. Interleukin-1β, tumor necrosis factor-α, malondialdehyde and SOD contents in the supernatant were evaluated. The expression of RAGE protein was measured by Western blotting.

KEY FINDINGS

The results demonstrated that AS-IV pre-treatment significantly improved BaP-induced dysfunction of EPCs in terms of proliferation, migration and adhesion. Furthermore, AS-IV reduced the production of reactive oxygen species, malondialdehyde, interleukin-1β and tumor necrosis factor-α of the BaP-treated EPCs. Finally AS-IV pre-treated EPCs showed an increased SOD activity and decreased RAGE protein expression.

SIGNIFICANCE

AS-IV is able to prevent BaP-mediated EPC dysfunction by at least inhibiting oxidative stress through the RAGE pathway.

Protective effects of tanshinone ⅡA on endothelial progenitor cells injured by tumor necrosis factor-α

Tanshinone IIA (Tan IIA) is a Traditional Chinese Medicine commonly used in Asian and Western countries for the prevention and treatment of cardiovascular disorders, such as atherosclerosis. Endothelial dysfunction and associated inflammatory processes have a critical role in the development of atherosclerosis. Endothelial progenitor cells (EPCs) have been demonstrated to be involved in certain aspects of the endothelial repair process. The present study aimed to investigate the putative protective effects of Tan IIA on EPCs injured by tumor necrosis factor-α (TNF-α). The potential effects of Tan IIA on TNF-α-stimulated EPC proliferation, migration, adhesion, in vitro tube formation ability and paracrine activity were investigated in the current study. The results indicated that TNF-α impaired EPC proliferation, migration, adhesion capacity and vasculogenesis ability in vitro as well as promoted EPC secretion of inflammatory cytokines, including monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) and soluble CD40 ligand (sCD40L). However, Tan IIA was able to reverse these effects. In conclusion, these findings demonstrated that Tan IIA may have the potential to protect EPCs against damage induced by TNF-α. Therefore, these results may provide evidence for the pharmacological basis of Tan IIA and its potential use in the prevention and treatment of early atherosclerosis associated with EPC and endothelial damage.

Transplantation of cryopreserved human umbilical cord blood-derived endothelial progenitor cells induces recovery of carotid artery injury in nude rats

Introduction

Transplantation of endothelial progenitor cells (EPCs) restores endothelial function in patients with endothelial dysfunction and initial denudation. The goal of the present study was to determine the effect of cryopreserved human umbilical cord blood (UCB)-derived EPC infusion on the repair of carotid artery injury in nude rats.

Methods

Mononuclear cells (MNCs) from human cryopreserved UCB and peripheral blood (PB) of patients with cardiovascular diseases and healthy volunteers were cultured in a conditioned medium. The in vitro migration, proliferation, adhesion, and survival capacities, as well as paracrine cytokine release of EPCs were investigated. EPC homing, induced reendothelialization, and the effect on neointima formation were also assessed in vivo.

Results

Patient-derived PB EPCs (PPB-EPCs) displayed decreased migration, proliferation, adhesion, and survival capabilities as compared to PB-EPCs from healthy volunteers (HPB-EPCs) and cryopreserved UCB-EPCs. However, there was no difference in the release of vascular endothelial growth factor (VEGF) and stromal cell derived factor 1 (SDF-1) between the three groups. Two weeks after transplantation, more labeled UCB-EPCs and HPB-EPCs than PPB-EPCs were found by cell tracking in the injury zone. Administration of PPB-EPCs, HPB-EPCs, and UCB-EPCs enhanced reendothelialization and inhibited neointima formation compared to the saline control. However, UCB-EPC and HPB-EPC infusion showed a greater improvement than PPB-EPCs.

Conclusions

Cryopreserved UCB-MNCs derived EPCs and HPB-EPCs show better responses to cytokines and vascular injury than PPB-EPCs. Thus, cryopreservation and delivery of cryopreserved autogenous UCB-EPCs or HPB-EPCs may be a promising vasculoprotective approach for patients with multiple cardiovascular risk factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0022-4) contains supplementary material, which is available to authorized users.

Endothelial progenitor cells--potential new avenues to improve neoangiogenesis and reendothelialization

The term endothelial progenitor cell (EPC) was established more than 10 years ago and is used to refer to a group of circulating cells that display endothelial lineage qualities and are able to home to areas of ischemia or vascular injury and to facilitate the repair of damaged blood vessels or develop new vessels as needed. This chapter reviews the current lineage relationships among all the cells called EPC and will clear the terminology used in EPC research. Furthermore, an overview of the clinical and in vitro research, as well as cytokine and drug interactions and potential EPC applications, is given.

Comparison of the efficiency of transplantation of bone marrow multipotent mesenchymal stromal cells cultured under normoxic and hypoxic conditions and their conditioned media on the model of acute lung injury

The therapeutic efficiency of intravenous injection of rat bone marrow multipotent mesenchymal stromal cells grown under conditions of normoxia and hypoxia (3% O2) and conditioned media from these cultures were compared on the rat model of acute lung injury induced by intraperitoneal injection of lipopolysaccharide. The best therapeutic efficiency was demonstrated by cells grown under hypoxic conditions. The effect of conditioned media was less pronounced and did not depend on the culturing conditions.

Influence of growth factors and cytokines on angiogenic function of endothelial progenitor cells: a review of in vitro human studies

Growth factors and cytokines released at sites of injury and inflammation play an important role in stimulating endothelial progenitor cell (EPC) migration to these sites. A comparative analysis of the literature shows under neutral in vitro conditions (pH 7.4), several growth factors and cytokines influenced favorably indices of EPC angiogenic function. They included SDF-1, VEGF, PlGF, FGF-2, NGF and IL-1β. Others, e.g. TNF-α, have an unfavorable influence. SDF-1 and VEGF in combination increased chemotactic cell migration and reduced apoptosis caused by serum starvation. Under acidic conditions (pH 6.5), the biological activity of certain growth factors may be impaired, although TPO, SCF and IL-3 were each able to rescue EPCs from acidic exposure apoptosis, a combination of these three factors stimulated cell proliferation and prevented apoptosis. Possible combinations of growth factors and cytokines together with EPC transplantation may provide for a greater extent of vessel repair and new vessel formation.

Nrf2 regulates angiogenesis: effect on endothelial cells, bone marrow-derived proangiogenic cells and hind limb ischemia

AIMS

Nuclear factor E2-related factor 2 (Nrf2), a key cytoprotective transcription factor, regulates also proangiogenic mediators, interleukin-8 and heme oxygenase-1 (HO-1). However, hitherto its role in blood vessel formation was modestly examined. Particularly, although Nrf2 was shown to affect hematopoietic stem cells, it was not tested in bone marrow-derived proangiogenic cells (PACs). Here we investigated angiogenic properties of Nrf2 in PACs, endothelial cells, and inflammation-related revascularization.

RESULTS

Treatment of endothelial cells with angiogenic cytokines increased nuclear localization of Nrf2 and induced expression of HO-1. Nrf2 activation stimulated a tube network formation, while its inhibition decreased angiogenic response of human endothelial cells, the latter effect reversed by overexpression of HO-1. Moreover, lack of Nrf2 attenuated survival, proliferation, migration, and angiogenic potential of murine PACs and affected angiogenic transcriptome in vitro. Additionally, angiogenic capacity of PAC Nrf2(-/-) in in vivo Matrigel assay and PAC mobilization in response to hind limb ischemia of Nrf2(-/-) mice were impaired. Despite that, restoration of blood flow in Nrf2-deficient ischemic muscles was better and accompanied by increased oxidative stress and inflammatory response. Accordingly, the anti-inflammatory agent etodolac tended to diminish blood flow in the Nrf2(-/-) mice.

INNOVATION

Identification of a novel role of Nrf2 in angiogenic signaling of endothelial cells and PACs.

CONCLUSION

Nrf2 contributes to angiogenic potential of both endothelial cells and PACs; however, its deficiency increases muscle blood flow under tissue ischemia. This might suggest a proangiogenic role of inflammation in the absence of Nrf2 in vivo, concomitantly undermining the role of PACs in such conditions.

Improving cardiovascular outcomes in rheumatic diseases: therapeutic potential of circulating endothelial progenitor cells

Patients with Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE) have a significantly increased risk of cardiovascular disease (CVD). The reason for this is unclear but may be due, at least in part, to the failure of endothelial repair mechanisms. Over the last 15 years there has been much interest in the mechanisms of endothelial renewal and its potential as a therapy for CVD. In the circulation there are two distinct populations of cells; myeloid angiogenic cells (MACs) which augment repair by the paracrine secretion of angiogenic factors, and outgrowth endothelial cells (OECs) which are true endothelial progenitor cells (EPCs) and promote vasculogenesis by differentiating into mature endothelium. There are marked abnormalities in the number and function of these cells in patients with RA and SLE. Inflammatory cytokines including interferon-alpha (IFNα) and tumour-necrosis factor alpha (TNFα) both impair MAC and OEC function ex vivo and may therefore contribute to the CVD risk in these patients. Whilst administration of mononuclear cells, MACs and other progenitors has improved cardiovascular outcomes in the acute setting, this is not a viable option in chronic disease. The pharmacological manipulation of MAC/OEC function in vivo however has the potential to significantly improve endothelial repair and thus reduce CVD in this high risk population.

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

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

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

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