Protective Factors and the Pathogenesis of Complications in Diabetes

Chronic complications of diabetes are due to myriad disorders of numerous metabolic pathways that are responsible for most of the morbidity and mortality associated with the disease. Traditionally, diabetes complications are divided into those of microvascular and macrovascular origin. We suggest revising this antiquated classification into diabetes complications of vascular, parenchymal, and hybrid (both vascular and parenchymal) tissue origin, since the profile of diabetes complications ranges from those involving only vascular tissues to those involving mostly parenchymal organs. A major paradigm shift has occurred in recent years regarding the pathogenesis of diabetes complications, in which the focus has shifted from studies on risks to those on the interplay between risk and protective factors. While risk factors are clearly important for the development of chronic complications in diabetes, recent studies have established that protective factors are equally significant in modulating the development and severity of diabetes complications. These protective responses may help explain the differential severity of complications, and even the lack of pathologies, in some tissues. Nevertheless, despite the growing number of studies on this field, comprehensive reviews on protective factors and their mechanisms of action are not available. This review thus focused on the clinical, biochemical, and molecular mechanisms that support the idea of endogenous protective factors, and their roles in the initiation and progression of chronic complications in diabetes. In addition, this review also aimed to identify the main needs of this field for future studies.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

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.

Intermediate Monocytes and Circulating Endothelial Cells: Interplay with Severity of Atherosclerosis in Patients with Coronary Artery Disease and Type 2 Diabetes Mellitus

The aim was to investigate the association of monocyte heterogeneity and presence of circulating endothelial cells with the severity of coronary atherosclerosis in patients with coronary artery disease (CAD) and type 2 diabetes mellitus (T2DM). We recruited 62 patients with CAD, including 22 patients with DM2. The severity of atherosclerosis was evaluated using Gensini Score. Numbers of classical (CD14++CD16-), intermediate (CD14++CD16+), and non-classical (CD14+CD16++) monocyte subsets; circulating endothelial progenitor cells; and the presence of circulating endothelial cells were evaluated. Counts and frequencies of intermediate monocytes, but not glycaemia parameters, were associated with the severity of atherosclerosis in diabetic CAD patients (rs = 0.689; p = 0.001 and rs = 0.632; p = 0.002, respectively). Frequency of Tie2+ cells was lower in classical than in non-classical monocytes in CAD patients (p = 0.007), while in patients with association of CAD and T2DM, differences between Tie2+ monocytes subsets disappeared (p = 0.080). Circulating endothelial cells were determined in 100% of CAD+T2DM patients, and counts of CD14++CD16+ monocytes and concentration of TGF-β predicted the presence of circulating endothelial cells (sensitivity 92.3%; specificity 90.9%; AUC = 0.930). Thus, intermediate monocytes represent one of the key determinants of the appearance of circulating endothelial cells in all the patients with CAD, but are associated with the severity of atherosclerosis only in patients with association of CAD and T2DM.

Topical Reappraisal of Molecular Pharmacological Approaches to Endothelial Dysfunction in Diabetes Mellitus Angiopathy

Diabetes mellitus (DM) is a frequent medical problem, affecting more than 4% of the population in most countries. In the context of diabetes, the vascular endothelium can play a crucial pathophysiological role. If a healthy endothelium—which is a dynamic endocrine organ with autocrine and paracrine activity—regulates vascular tone and permeability and assures a proper balance between coagulation and fibrinolysis, and vasodilation and vasoconstriction, then, in contrast, a dysfunctional endothelium has received increasing attention as a potential contributor to the pathogenesis of vascular disease in diabetes. Hyperglycemia is indicated to be the major causative factor in the development of endothelial dysfunction. Furthermore, many shreds of evidence suggest that the progression of insulin resistance in type 2 diabetes is parallel to the advancement of endothelial dysfunction in atherosclerosis. To present the state-of-the-art data regarding endothelial dysfunction in diabetic micro- and macroangiopathy, we constructed this literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We interrogated five medical databases: Elsevier, PubMed, PMC, PEDro, and ISI Web of Science.

Recent Advancements in the Medical Treatment of Diabetic Retinal Disease

Diabetic retinal disease remains one of the most common complications of diabetes mellitus (DM) and a leading cause of preventable blindness. The mainstay of management involves glycemic control, intravitreal, and laser therapy. However, intravitreal therapy commonly requires frequent hospital visits and some patients fail to achieve a significant improvement in vision. Novel and long-acting therapies targeting a range of pathways are warranted, while evidence to support optimal combinations of treatments is currently insufficient. Improved understanding of the molecular pathways involved in pathogenesis is driving the development of therapeutic agents not only targeting visible microvascular disease and metabolic derangements, but also inflammation and accelerated retinal neurodegeneration. This review summarizes the current and emerging treatments of diabetic retinal diseases and provides an insight into the future of managing this important condition.

Effect of Peptidylarginine Deiminase 4 on Endothelial Progenitor Cell Function in Peripheral Arterial Disease

At present, the global prevalence of peripheral arterial disease is increasing year by year, and it has become a worldwide disease. Studies have shown that transplanting endothelial progenitor cells (EPCs) into ischemic tissues can improve the tissue ischemia, thereby having a therapeutic effect on peripheral arterial diseases. This indicates that EPCs play a therapeutic effect in peripheral arterial disease. Recent studies have shown that peptidylarginine deiminase (PAD) is involved in the regulation of epigenetics and its inhibitor Cl-amidine can improve endothelium-dependent vasodilation and significantly reduce the formation of arterial thrombosis. It can also play a role in hematopoietic stem cells that share the same origin with EPCs. Therefore, we speculate that PAD4 may also have an effect on EPCs through a similar mechanism, thereby participating in the damage and repair of peripheral arterial disease. Therefore, we first detected the expression of PAD4 in EPCs of peripheral arterial disease and detected changes in the number and function of endothelial progenitor cells in peripheral blood after injecting the PAD4 inhibitor Cl-amidine into mice. A mouse model of lower limb ischemia was established to explore the effect of PAD4 on the function of EPCs in peripheral arterial disease. The results show that PAD4 is highly expressed in peripheral arterial diseases and the PAD4 inhibitor Cl-amidine can increase the number of EPCs and can treat peripheral arterial diseases by improving the proliferation, migration, and vascularization of EPCs.

Abnormal macrophage polarization impedes the healing of diabetes-associated tooth sockets

Patients with poorly controlled type 2 diabetes mellitus (T2DM) often experience delayed tooth extraction socket (TES) healing. Delayed healing is often associated with an aberrant inflammatory response orchestrated by either M1 pro-inflammatory or M2 anti-inflammatory macrophages. However, the precise mechanism for the attenuated TES healing remains unclear. Here we used diet-induced T2DM mice as a model to study TES. Compared with the control group, the T2DM group showed delayed TES healing and diminished expression of osteogenic and angiogenic genetic profiles. Meanwhile, we detected a more inflammatory profile, with more M1 macrophages and TNF-α expression and less M2 macrophages and PPARγ expression, in TES in the T2DM group when compared to control mice. In vitro co-culture models showed that M1 macrophages inhibited the osteogenic capacity of bone marrow stromal cells and the angiogenic capacity of endothelial cells while M2 macrophages showed an opposite effect. In addition, we constructed a gelatin/β-TCP scaffold with IL-4 to induce macrophage transformation towards M2 polarization. In vitro analyses of the hybrid scaffold revealed sustained release of IL-4 and a phenotype switch to M2 macrophages. Finally, we demonstrated that sustained IL-4 release significantly increased expression of osteogenic and angiogenic genetic profiles and improved TES healing in T2DM mice. Together, we report that increased M1 and decreased M2 macrophage polarization may be responsible for delayed TES healing in T2DM patients through abnormal expression of TNF-α and PPARγ. This imbalance negatively influences osteogenesis and angiogenesis, two of the most important biological factors in bone wound healing. Enhancing M2 macrophage polarization with IL-4 delivery system may represent a potential strategy for promoting the healing of TES in T2DM patients.

Exploring the Pharmacological Mechanism of Liuwei Dihuang Decoction for Diabetic Retinopathy: A Systematic Biological Strategy-Based Research

OBJECTIVE

To explore the pharmacological mechanism of Liuwei Dihuang decoction (LDD) for diabetic retinopathy (DR).

METHODS

The potential targets of LDD were predicted by PharmMapper. GeneCards and other databases were used to collect DR genes. Cytoscape was used to construct and analyze network DR and LDD's network, and DAVID was used for Gene Ontology (GO) and pathway enrichment analysis. Finally, animal experiments were carried out to verify the results of systematic pharmacology.

RESULTS

Five networks were constructed and analyzed: (1) diabetic retinopathy genes' PPI network; (2) compound-compound target network of LDD; (3) LDD-DR PPI network; (4) compound-known target network of LDD; (5) LDD known target-DR PPI network. Several DR and treatment-related targets, clusters, signaling pathways, and biological processes were found. Animal experiments found that LDD can improve the histopathological changes of the retina. LDD can also increase erythrocyte filtration rate and decrease the platelet adhesion rate (P < 0.05) and decrease MDA and TXB2 (P < 0.05). Compared with the model group, the retinal VEGF and HIF-1α expression in the LDD group decreased significantly (P < 0.05).

CONCLUSION

The therapeutic effect of LDD on DR may be achieved by interfering with the biological processes (such as response to insulin, glucose homeostasis, and regulation of angiogenesis) and signaling pathways (such as insulin, VEGF, HIF-1, and ErbB signaling pathway) related to the development of DR that was found in this research.

The cells involved in the pathological process of diabetic retinopathy

Diabetic retinopathy(DR) is an expanding global health problem, the exact mechanism of which has not yet been clarified clearly, new insights into retinal physiology indicate that diabetes-induced retinal dysfunction may be viewed as an impairment of the retinal neurovascular unit, including retinal ganglion cells, glial cells, endothelial cells, pericytes, and retinal pigment epithelium. Different retinal cells have unique structure and functions, while the interactions among which are less known. Cells are the basic unit of organism structure and function, their impairment could lead to abnormal physiological functions and even organ disorder. Considering the body is multi-dimension and the complexity of DR, one point or a single type of cell can't be used to illustrate the mechanism of occurrence and development of DR. In this review, we provided a systematic and comprehensive elaboration of the cells that are involved in the process of DR. We underlined the importance of considering the neurovascular unit, not just retinal vascular and neural cells, in understanding the pathophysiology of DR. Our studies provided a better understanding of the pathological process in DR and provide a theoretical basis for further research.

An Endostatin-lentivirus (ES-LV)-EPC gene therapy agent for suppression of neovascularization in oxygen-induced retinopathy rat model

BACKGROUND

Transplantation of gene transfected endothelial progenitor cells (EPCs) has provided novel methods for tumor neovascularization therapy but not for ocular disease therapy. This study aimed to investigate the efficacy of endostatin transfected EPCs in retinal neovascularization therapy.

RESULTS

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) showed the high expression of endostatin in endostatin-lentivirus-EPCs. The neovascularization leakage area and the number of preretinal neovascular cell nuclei were significantly decreased in the endostatin-lentivirus and endostatin-lentivirus-EPC groups, and the effects of these two treatments on inhibiting retinal neovascularization were almost the same. These two groups also showed the greater retinal distribution of endostatin. Intravitreal injections of endostatin-lentivirus-EPCs inhibited retinal neovascularization, vascular endothelial growth factor (VEGF) and CD31 expression, and increased endostatin expression in vivo. Endostatin-lentivirus-EPCs targeted and prevented pathologic retinal neovascularization.

CONCLUSIONS

Gene-combined EPCs represent a potential new therapeutic agent for the treatment of neovascular eye diseases.

Alterations in the Levels of Circulating and Endothelial Progenitor Cells Levels in Young Adults with Type 1 Diabetes: A 2-Year Follow-Up from the Observational METRO Study

PURPOSE

Type 1 diabetes is associated with high risk of cardiovascular disease (CVD). Reduced levels of circulating progenitor cells (CPCs) and endothelial progenitor cells (EPCs) have been indicated as a risk factor for adverse cardiovascular outcomes and death in people at high cardiovascular risk. The aim of the present study was to evaluate the change in CPCs and EPCs levels in a population of young type 1 diabetic patients treated with intensive insulin regimen over a period of 2 years.

PATIENTS AND METHODS

A total of 204 type 1 diabetic patients, of whom 84 treated with insulin pump (CSII) and 120 with multiple daily insulin injections (MDI), completed a 2-year follow-up. Clinical measurements, including the indices of glycemic control and glucose variability, were collected at baseline and after 2 years. Both CPC and EPC cell count were assessed by flow cytometry.

RESULTS

Mean age of participants was 24.5 years and mean diabetes duration was 13.6 years. After 2 years, we found a significant reduction of HbA1c (-0.3% versus baseline, P <0.001), associated with decrease in mean amplitude of glucose excursion (MAGE) (-0.5 mmol/L versus baseline, P<0.001), continuous overall net glycemic action (CONGA) (-0.2 mmol/L versus baseline, P=0.006), and blood glucose standard deviation (BGSD) (-0.2 mmol/L versus baseline, P<0.001). The number of all EPCs phenotypes, but not CPC cell count, significantly raised up in the entire population, with higher increase in CSII group. MAGE resulted as an independent predictor for increased levels of both CD34+ (P = 0.020) and CD34+KDR+ (P = 0.004) cell count in the whole population.

CONCLUSION

Over a 2-year follow-up, young type 1 diabetic patients showed an increase in circulating EPCs levels, which was higher in patients with CSII. Glucose variability resulted as an independent predictor of the raised levels of EPCs in this selected population.

rhBMP‑7 suppresses TGF‑β1‑induced endothelial to mesenchymal transition in circulating endothelial cells by regulating Smad5

Endothelial to mesenchymal transition (EndMT) has been confirmed to participate in several cardiovascular diseases. In addition, EndMT of circulating endothelial cells (CECs) contributes to the pathology of musculoskeletal injury. However, little is known about the molecular mechanism of CECs undergoing EndMT. In the present study, human CECs were isolated and identified using anti‑CD146‑coupled magnetic beads. CECs were exposed to transforming growth factor (TGF)‑β1 or TGF‑β1 + recombinant human bone morphogenetic protein 7 (rhBMP‑7) or TGF‑β1 + rhBMP‑7 + Smad5 antagonist Jun activation domain‑binding protein 1. Vascular endothelial (VE)‑cadherin and vimentin expression were detected by immunofluorescence staining in TGF‑β1‑treated CECs. The expression levels of von Willebrand factor (vWF), E‑selectin, VE‑cadherin, vimentin, fibronectin, α smooth muscle actin (α‑SMA) and Smad2/3 were detected by reverse transcription‑quantitative PCR or western blot analysis. It was identified that rhBMP‑7 attenuated TGF‑β1‑induced endothelial cell injury. TGF‑β1 could induce the EndMT process in CECs, as confirmed by the co‑expression of VE‑cadherin and vimentin. TGF‑β1 significantly reduced the expression of VE‑cadherin, and induced the expression of vimentin, fibronectin and α‑SMA. rhBMP‑7 reversed the effects of TGF‑β1 on the expression of these genes. Additionally, Smad5 antagonist reversed the effects of rhBMP‑7 on TGF‑β1‑induced EndMT, and upregulated rhBMP‑7‑inhibited Smad2/3 expression. In conclusion, TGF‑β1 could induce EndMT in CECs and rhBMP‑7 may suppress this process by regulating Smad5.

Polysaccharide peptide (PsP) Ganoderma lucidum: a potential inducer for vascular repair in type 2 diabetes mellitus model

INTRODUCTION

The increasing blood glucose level due to insulin resistance which occurs in diabetes mellitus (DM) may cause vascular damage. This study aims to prove the effect of the polysaccharide peptide (PsP) Ganoderma lucidum on improving vascular damage through an increase of circulating endothelial cells and circulating endothelial cells (CEC) ratio, decreased H2O2, triglyceride (TG), total cholesterol (TC) and insulin resistance in type 2 DM.

METHODS

Our study is a true experimental study with randomized posttest control group design that used 35 Wistar rats divided into five groups: normal, control (+) and three groups of different variant PsP doses 50, 150 and 300 mg/kg BW (n=7).

RESULTS

By using one-way ANOVA and post-hoc Duncan test, the results show a significant increase of endothelial progenitor cell (EPC) concentration (p=0.000) and ratio EPC:CEC (0.000) by dose-dependent fashion and also reduced CEC concentration (p=0.001), H2O2 (p=0.03), TG (p=0.001), TC (p=0.01) and insulin resistance (p=0.003).

CONCLUSION

In this study, PsP induced endothelial repairing process and reduced the risk factor with 300 mg/kg BW as optimum dose. However, further research on EPC and CEC detection markers is important. Further research on PsP and clinical trial for commercial uses is also needed.

Effects and Underlying Mechanisms of Bioactive Compounds on Type 2 Diabetes Mellitus and Alzheimer's Disease

Type 2 diabetes mellitus is a complicated metabolic disorder characterized by hyperglycemia and glucose intolerance. Alzheimer's disease is a progressive brain disorder characterized by a chronic loss of cognitive and behavioral function. Considering the shared characteristics of both diseases, common therapeutic and preventive agents may be effective. Bioactive compounds such as polyphenols, vitamins, and carotenoids found in vegetables and fruits can have antioxidant and anti-inflammatory effects. These effects make them suitable candidates for the prevention or treatment of diabetes and Alzheimer's disease. Increasing evidence from cell or animal models suggest that bioactive compounds may have direct effects on decreasing hyperglycemia, enhancing insulin secretion, and preventing formation of amyloid plaques. The possible underlying molecular mechanisms are described in this review. More studies are needed to establish the clinical effects of bioactive compounds.

Erectile dysfunction treated with intracavernous stem cells: A promising new therapy?

In the past decades, great interest has been shown in the development of new therapies for erectile dysfunction. Stem cell therapy has generated promising results in numerous preclinical trials in animal models, which is why has led to the development of the first clinical trials in humans. The main cause involved in the pathophysiology of erectile dysfunction is vascular damage related to endothelial and neuronal injury. The interest in stem cell therapy is justified by their capability to differentiate into specific damaged tissues, including endothelium and nervous tissue, and induction of the host own cell proliferation. Despite the great effort of the many studies carried out to date, knowledge about biological effects, therapeutic efficacy and safety of stem cells therapy for erectile dysfunction is still very limited.

Simvastatin attenuates the aberrant expression of angiogenic factors induced by glucose variability

AIM

Over the last few years, studies have indicated that fluctuant hyperglycemia is very likely to increase the risk of cardiovascular complications of diabetes. Statins are widely used in diabetes for the prevention of cardiovascular complications, but it is still not clear whether simvastatin could also prevent glycaemic variability - induced aberrant angiogenesis which plays a significant role in the development of atherosclerosis.

METHODS

Wistar rats were divided into four groups: (1) simvastatin-treated (20 mg/kg for 8 consecutive weeks) type 2 diabetes rat model with daily glucose excursions, (2) placebo-treated type 2 diabetes rat model with daily glucose excursions, (3) placebo-treated stable well-controlled type 2 diabetes rat model and (4) placebo-treated non-diabetic rats. Daily glucose fluctuations and several angiogenic factors: cVEGF, mRNA VEGF, VEGF-R1, VEGF-R2, TGF-beta expression, circulating endothelial and progenitor endothelial cells were measured in all groups.

RESULTS

Simvastatin decreased several factors enhanced by glucose excursions: circulating VEGF, mRNA TGF-beta expression in the myocardium and mRNA VEGFR-2 expression in the aorta. Simvastatin increased some factors attenuated by glucose fluctuations: mRNA VEGF expression and mRNA VEGFR-1 expression in the myocardium and in the aorta. In the simvastatin-treated group with glycaemic variability, the percentage of circulating endothelial cells was lower and the percentage of progenitor endothelial cells in peripheral blood was higher than in the placebo-treated rats with glucose-fluctuations.

CONCLUSIONS

Simvastatin used in the rat model of type 2 diabetes with glucose variability reduces glucose variability and limits glucose fluctuations-induced changes in the expression of angiogenic factors in the cardiovascular system.

MiR-155 targets PTCH1 to mediate endothelial progenitor cell dysfunction caused by high glucose

Endothelial progenitor cells (EPCs) are involved in diabetes-associated complications, including diabetic foot ulcer (DFU). Recent reports showed that miR-155 downregulation promotes wound healing in diabetic rats and ameliorates endothelial injury induced by high glucose, but its role in DFU is unknown. We found that miR-155 was overexpressed in EPCs from patients with DFU and in high glucose-induced EPCs from healthy people. Reductions in cell viability, migration, tube formation and nitric oxide production, as well as increases in lactated hydrogenase, cell apoptosis, and reactive oxygen species induced by high glucose, were enhanced by miR-155 overexpression and restrained by miR-155 inhibition. Additionally, dual-luciferase reporter assay demonstrated that miR-155 directly targeted the 3' untranslated region of patched-1 (PTCH1), a receptor of the sonic hedgehog signaling pathway, and downregulated the mRNA and protein expression of PTCH1. qRT-PCR and Western blot results revealed that the PTCH1 was downregulated in EPCs treated with high glucose. Silencing PTCH1 by PTCH1 siRNA alleviated the protective effect of anti-miR-155 on high glucose-induced EPC dysfunction. Our results indicate that miR-155 worsened high glucose-induced EPC function by downregulating PTCH1. These findings suggest that miR-155 may be a potential therapeutic target for DFU.

New arguments for beneficial effects of alpha-lipoic acid on the cardiovascular system in the course of type 2 diabetes

PURPOSE

Alpha-lipoic acid (ALA), widely known as an antioxidant, modifies also serum levels of angiogenic factors in type 2 diabetic patients. These pharmacological activities may influence the status of the cardiovascular system. Taking into consideration that diabetes is related to the increased cardiovascular risk we investigated several effects of ALA on angiogenic factors in the myocardium and in the aortal wall using a rat model of type 2 diabetes.

METHODS

Diabetes was induced in Wistar rats by a fat-rich diet and by intraperitoneal injection of a small dose of streptozotocin (30 mg/kg). Animals were divided into 3 groups: ALA-treated type 2 diabetes rat model, placebo-treated type 2 diabetes rat model and placebo-treated non-diabetic rats. ALA was administered orally once a day, 20 mg/kg, for 8 consecutive weeks. mRNA VEGF, VEGF-R1 and VEGF-R2 expression was measured in the myocardium and the aortal wall, simultaneously with circulating VEGF and circulating endothelial cells (cEC) and endothelial progenitor cells (cEPC).

RESULTS

ALA induced pro-angiogenic effect in the myocardium of rats with diabetes increasing mRNA VEGF expression and decreasing mRNA VEGFR-1 expression, while in the aortal wall ALA increased mRNA VEGFR-2 and VEGFR-1 expression. cVEGF in the ALA-treated group was higher comparing to both control groups. It was revealed that cEC percentage in the ALA-treated group was decreased with no effect on the percentage of cEPC.

CONCLUSIONS

In summary, the current data provide novel findings about potential beneficial effects of ALA on angiogenic factors in the cardiovascular system, especially on myocardium, in the course of type 2 diabetes.

The Impact of Type 2 Diabetes on Bone Fracture Healing

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease known by the presence of elevated blood glucose levels. Nowadays, it is perceived as a worldwide epidemic, with a very high socioeconomic impact on public health. Many are the complications caused by this chronic disorder, including a negative impact on the cardiovascular system, kidneys, eyes, muscle, blood vessels, and nervous system. Recently, there has been increasing evidence suggesting that T2DM also adversely affects the skeletal system, causing detrimental bone effects such as bone quality deterioration, loss of bone strength, increased fracture risk, and impaired bone healing. Nevertheless, the precise mechanisms by which T2DM causes detrimental effects on bone tissue are still elusive and remain poorly studied. The aim of this review was to synthesize current knowledge on the different factors influencing the impairment of bone fracture healing under T2DM conditions. Here, we discuss new approaches used in recent studies to unveil the mechanisms and fill the existing gaps in the scientific understanding of the relationship between T2DM, bone tissue, and bone fracture healing.

Vascular Health Profile predicts cardiovascular outcomes in patients with diabetes

BACKGROUND

We previously reported the development of a novel high dimensional cytomic assay, the Vascular Health Profile (VHP) based on measurements of angiogenic circulating hematopoietic stem and progenitor cells (CHSPCAng ) and extracellular vesicles (EVs), that discovered a unique signature, differentiating the vascular status of diabetics and normal healthy controls. Here, we present data from a 3-year follow-up to evaluate the power of the VHP to identify individuals at risk for cardiovascular (CV) events.

METHODS

The original data were generated as previously described by measuring a broad panel of progenitor cells and EVs and profiled using cytometric fingerprinting. Subjects were classified into groups according to the occurrence of adjudicated CV events including myocardial infarction, stroke, major adverse cardiovascular events, revascularization, and irregular rhythm. Cross-validated Linear Discriminate Analysis (LDA) models were constructed and used to predict the occurrence of events, and were evaluated for predictive accuracy (AUC, area under the curve) using receiver operating characteristic (ROC) analysis.

RESULTS

Over the period of this analysis, follow-up data was obtained on 87 subjects, with 32 events occurring overall, and only in the diabetic group. In all cases, the VHP added significant predictive power, in the form of ROC analysis, for all evaluated outcomes with the exception of irregular rhythm.

CONCLUSIONS

The VHP, a relatively simple blood test, can provide sensitive and clinically relevant information on the vascular status of a patient that may be useful for a variety of applications including drug development, clinical risk assessment, and companion diagnostics. © 2015 International Clinical Cytometry Society.

Protective effect and mechanism of lycopene on endothelial progenitor cells (EPCs) from type 2 diabetes mellitus rats

Endothelial progenitor cells (EPCs), widely existing in bone marrow and peripheral blood, are involved in the repair of injured vascular endothelium and angiogenesis which are important to diabetic mellitus (DM) patients with vascular complications. The number and the function of EPCs are related to the advanced glycation end products (AGEs) generated in DM patients. Lycopene (Lyc) is an identified natural antioxidant that protects EPCs under the microenvironment of AGEs from damage. However, the underlying mechanism remains unclear. To investigate the effect of Lyc on EPCs, we isolated EPCs from DM rat bone marrow and determined cell proliferation, cell cycle,apoptosis and autophagy of EPCs. The present study showed that 10μg/mL Lyc improved cell proliferation and had low cytotoxicity in the presence of AGEs. In addition, Lyc rescued S phase of the cell cycle arrest, reduced apoptosis rate and decreased autophagic reaction including ROS and mitochondrial membrane potential (MMP) of EPCs. Moreover, Lyc combined use of autophagy inhibitors, 3-MA, had better protective effects. Taken together, our data suggests that Lyc promotes EPCs survival and protect EPCs from apoptosis and oxidative autophagy induced by AGEs, further remaining the number and function of EPCs. This study provides new insights into Lyc protective mechanism of AGEs-induced oxidative autophagy in EPCs from DM patients and offers a new therapy for DM vascular complications.

Plerixafor improves the endothelial health balance. The effect of diabetes analysed by polychromatic flow cytometry

BACKGROUND AND AIMS

Diabetes damages the endothelium and reduces the availability of bone marrow (BM)-derived endothelial progenitor cells (EPCs). The mobilization of hematopoietic stem cells (HSCs) and EPCs in response to G-CSF is impaired by diabetes, owing to CXCL12 dysregulation. We have previously shown that the CXCR4/CXCL12 disruptor plerixafor rescues HSC and EPC mobilization in diabetes. We herein explored the effects of plerixafor on HSCs, EPCs, and circulating endothelial cells (CECs) in patients with and without diabetes.

METHODS

We re-analysed data gathered in the NCT02056210 trial, wherein patients with (n = 10) and without diabetes (n = 10) received plerixafor to test stem/progenitor cell mobilization. We applied a novel and very specific polychromatic flow cytometry (PFC) approach to identify and quantify HSCs, EPCs, and CECs.

RESULTS

We found that 7-AAD(-)Syto16(+)CD34(+)CD45(dim) HSC levels determined by PFC strongly correlated to the traditional enumeration of CD34(+) cells, whereas 7-AAD(-)Syto16(+)CD34(+)CD45(neg)KDR(+) EPCs were unrelated to the traditional enumeration of CD34(+)KDR(+) cells. Using PFC, we confirmed that plerixafor induces rapid mobilization of HSCs and EPCs in both groups, with a marginally significant defect in patients with diabetes. Plerixafor reduced live (7-AAD(-)) and dead (7-AAD(+)) Syto16(+)CD34(bright)CD45(neg)CD146(+) CECs more in patients without than in those with diabetes. The EPC/CEC ratio, a measure of the vascular health balance, was increased by plerixafor, but less prominently in patients with that in those without diabetes.

CONCLUSIONS

In addition to rescuing defective mobilization associated with diabetes, plerixafor improves the balance between EPCs and CECs, but the latter effect is blunted in patients with diabetes.

Bone Marrow-Derived Stem Cells: a Mixed Blessing in the Multifaceted World of Diabetic Complications

Diabetes is one of the main economic burdens in health care, which threatens to worsen dramatically if prevalence forecasts are correct. What makes diabetes harmful is the multi-organ distribution of its microvascular and macrovascular complications. Regenerative medicine with cellular therapy could be the dam against life-threatening or life-altering complications. Bone marrow-derived stem cells are putative candidates to achieve this goal. Unfortunately, the bone marrow itself is affected by diabetes, as it can develop a microangiopathy and neuropathy similar to other body tissues. Neuropathy leads to impaired stem cell mobilization from marrow, the so-called mobilopathy. Here, we review the role of bone marrow-derived stem cells in diabetes: how they are affected by compromised bone marrow integrity, how they contribute to other diabetic complications, and how they can be used as a treatment for these. Eventually, we suggest new tactics to optimize stem cell therapy.

Bee Venom Accelerates Wound Healing in Diabetic Mice by Suppressing Activating Transcription Factor-3 (ATF-3) and Inducible Nitric Oxide Synthase (iNOS)-Mediated Oxidative Stress and Recruiting Bone Marrow-Derived Endothelial Progenitor Cells

Multiple mechanisms contribute to impaired diabetic wound healing including impaired neovascularization and deficient endothelial progenitor cell (EPC) recruitment. Bee venom (BV) has been used as an anti-inflammatory agent for the treatment of several diseases. Nevertheless, the effect of BV on the healing of diabetic wounds has not been studied. Therefore, in this study, we investigated the impact of BV on diabetic wound closure in a type I diabetic mouse model. Three experimental groups were used: group 1, non-diabetic control mice; group 2, diabetic mice; and group 3, diabetic mice treated with BV. We found that the diabetic mice exhibited delayed wound closure characterized by a significant decrease in collagen production and prolonged elevation of inflammatory cytokines levels in wounded tissue compared to control non-diabetic mice. Additionally, wounded tissue in diabetic mice revealed aberrantly up-regulated expression of ATF-3 and iNOS followed by a marked elevation in free radical levels. Impaired diabetic wound healing was also characterized by a significant elevation in caspase-3, -8, and -9 activity and a marked reduction in the expression of TGF-β and VEGF, which led to decreased neovascularization and angiogenesis of the injured tissue by impairing EPC mobilization. Interestingly, BV treatment significantly enhanced wound closure in diabetic mice by increasing collagen production and restoring the levels of inflammatory cytokines, free radical, TGF-β, and VEGF. Most importantly, BV-treated diabetic mice exhibited mobilized long-lived EPCs by inhibiting caspase activity in the wounded tissue. Our findings reveal the molecular mechanisms underlying improved diabetic wound healing and closure following BV treatment. J. Cell. Physiol. 231: 2159-2171, 2016. © 2016 Wiley Periodicals, Inc.

Endothelial Progenitor Cells for Diagnosis and Prognosis in Cardiovascular Disease

Objective. To identify, evaluate, and synthesize evidence on the predictive power of circulating endothelial progenitor cells (EPCs) in cardiovascular disease, through a systematic review of quantitative studies. Data Sources. MEDLINE was searched using keywords related to "endothelial progenitor cells" and "endothelium" and, for the different categories, respectively, "smoking"; "blood pressure"; "diabetes mellitus" or "insulin resistance"; "dyslipidemia"; "aging" or "elderly"; "angina pectoris" or "myocardial infarction"; "stroke" or "cerebrovascular disease"; "homocysteine"; "C-reactive protein"; "vitamin D". Study Selection. Database hits were evaluated against explicit inclusion criteria. From 927 database hits, 43 quantitative studies were included. Data Syntheses. EPC count has been suggested for cardiovascular risk estimation in the clinical practice, since it is currently accepted that EPCs can work as proangiogenic support cells, maintaining their importance as regenerative/reparative potential, and also as prognostic markers. Conclusions. EPCs showed an important role in identifying cardiovascular risk conditions, and to suggest their evaluation as predictor of outcomes appears to be reasonable in different defined clinical settings. Due to their capability of proliferation, circulation, and the development of functional progeny, great interest has been directed to therapeutic use of progenitor cells in atherosclerotic diseases. This trial is registered with registration number: Prospero CRD42015023717.

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.

Vascular Ageing and Exercise: Focus on Cellular Reparative Processes

Ageing is associated with an increased risk of developing noncommunicable diseases (NCDs), such as diabetes and cardiovascular disease (CVD). The increased risk can be attributable to increased prolonged exposure to oxidative stress. Often, CVD is preceded by endothelial dysfunction, which carries with it a proatherothrombotic phenotype. Endothelial senescence and reduced production and release of nitric oxide (NO) are associated with “vascular ageing” and are often accompanied by a reduced ability for the body to repair vascular damage, termed “reendothelialization.” Exercise has been repeatedly shown to confer protection against CVD and diabetes risk and incidence. Regular exercise promotes endothelial function and can prevent endothelial senescence, often through a reduction in oxidative stress. Recently, endothelial precursors, endothelial progenitor cells (EPC), have been shown to repair damaged endothelium, and reduced circulating number and/or function of these cells is associated with ageing. Exercise can modulate both number and function of these cells to promote endothelial homeostasis. In this review we look at the effects of advancing age on the endothelium and these endothelial precursors and how exercise appears to offset this “vascular ageing” process.

Circulating endothelial progenitor cells and angiogenic factors in diabetes complicated diabetic foot and without foot complications

INTRODUCTION

Data about angiogenic factors in diabetic foot syndrome (DFS) are insufficient. Therefore, in the present study we focus on circulating endothelial progenitor cells (EPCs) and two major angiogenic factors: vascular endothelial growth factor (VEGF-A) and fibroblast growth factor (FGF-2) in patients with DFS.

MATERIALS AND METHODS

We included 75 subjects: 45 patients with type 2 diabetes and 30 controls. The study group was divided into 2 subgroups: 23 patients with diabetic foot and 22 patients without diabetic complications. The concentration of VEGF-A, soluble VEGF receptor 2 (sVEGF-R2) and FGF-2 were measured in plasma samples. The number of circulating EPCs was determined in peripheral venous blood. The number of endothelial progenitor cells was measured with FACSCalibur flow cytometer using monoclonal antibodies directed against antigens specific for EPCs.

RESULTS

In our study we observed significant higher levels of VEGF-A and FGF-2 and lower sVEGF-R2 concentration in patients with T2DM compared to healthy subjects. The conducted analysis showed decreased levels of VEGF-A and elevated levels of FGF-2 in patients with DM complicated DFS compared to diabetic patients without DFS. Increased circulating EPCs number was reported in patients with DFS, and the difference was almost statistically significant.

CONCLUSIONS

The high concentration of VEGF-A and FGF-2, and a positive correlation between them indicate their participation in the process of angiogenesis in T2DM. Decreased sVEGF-R2 may result from inactivation of VEGF-A during complexes formation.

The real face of endothelial progenitor cells - Circulating angiogenic cells as endothelial prognostic marker?

Endothelial progenitor cells (EPCs) have been extensively studied for almost 19 years now and were considered as a potential marker for endothelial regeneration ability. On the other hand, circulating endothelial cells (CEC) were studied as biomarker for endothelial injury. Yet, in the literature, there is also huge incoherency in regards to terminology and protocols used. This results in misleading conclusions on the role of so called "EPCs", especially in the clinical field. The discrepancies are mainly due to strong phenotypic overlap between EPCs and circulating angiogenic cells (CAC), therefore changes in "EPC" terminology have been suggested. Other factors leading to inconsistent results are varied definitions of the studied populations and the lack of universal data reporting, which could strongly affect data interpretation. The current review is focused on controversies concerning the use of "EPCs"/CAC and CEC as putative endothelial diagnostic markers.

Poor outcome of experimental ischemic stroke in type 2 diabetic rats: impaired circulating endothelial progenitor cells mobilization

BACKGROUND

It is well accepted that type 2 diabetic mellitus (T2DM) results in the poor outcome of ischemic stroke. However, the mechanisms by which T2DM causes aggravated cerebral ischemic/reperfusion (I/R) injury are not clear. Recently, endothelial progenitor cells (EPCs) are considered to be related with the outcome of ischemic stroke. More importantly, T2DM can affect the function of circulating EPCs. This study tried to investigate whether T2DM worsens the cerebral I/R injury via affecting circulating EPCs.

METHODS

We used high-fat diet-fed and low-dose streptozotocin-treated male rats receiving middle cerebral artery occlusion surgery as animal model of focal cerebral I/R injury with T2DM (diabetic operated). And the rats were divided into 4 groups: normal sham, diabetic sham, normal operated, and diabetic operated. We measured the circulating EPCs counts and the levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in peripheral plasma of 4 groups.

RESULTS

We found that diabetic rats subjected to I/R exhibited significantly severe deterioration in neurologic deficits compared with nondiabetic counterparts, which manifested higher infarct volume and cell apoptosis as well as lower neurologic defective score. There was no significant difference on the plasma glucose of groups before cerebral I/R injury compared with that of the groups posterior to cerebral I/R injury despite cerebral I/R injury had the tendency to increase the plasma glucose no matter in the presence or the absence of T2DM. In addition, there were the marked downregulation of circulating EPCs counts and the levels of VEGF and eNOS in diabetic rats before the cerebral I/R injury. Despite I/R injury without T2DM, there was a significant increase in the circulating EPCs counts, the circulating EPCs counts in I/R injury with T2DM group were significantly decreased compared with those in the other 3 groups. We also observed that the level of eNOS was significantly improved by I/R injury without considering the presence of T2DM.

CONCLUSIONS

Thus, our present study suggested that it might be the impaired EPCs mobilization into the blood that contributed to the worse outcome of cerebral I/R injury with T2DM.

Effects of krill oil on endothelial function and other cardiovascular risk factors in participants with type 2 diabetes, a randomized controlled trial

OBJECTIVE

The purpose of this trial was to evaluate the effect of krill oil supplementation, a source of ω-3 fatty acids, on cardiovascular disease risk factors and blood glucose control among participants with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A randomized, double-blind controlled cross-over trial was employed. Outcomes assessed were: endothelial function, blood lipids, glucose, glycated hemoglobin, serum antioxidant level, C peptide, and calculated Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) scores. Participants were randomized to either krill oil or olive oil supplementation for 4 weeks, underwent a 2-week washout period, and then crossed to the other supplementation for 4 weeks. All participants were then offered an additional 17 weeks of krill supplementation. Testing occurred at 3 time points: baseline, after first supplementation, and after second supplementation. Testing also occurred after an optional 17 weeks of krill oil supplementation. Difference scores were calculated for each participant in both sequences (ie, differences in outcome measures in the first and second period of the sequence). The mean and SD of the scores in the 2 sequence groups were used to test for differences between treatment effects at a significance level of p<0.05.

RESULTS

A total of 47 participants were included in the initial cross-over study. Participants who received krill oil for 4 weeks had an improvement in their endothelial function and a reduction in blood C peptide levels and HOMA scores as compared with the olive oil. A total of 34 participants completed the additional 17-week supplementation period. When compared with their respective baseline measures, these participants had a statistically significant improvement in endothelial function and blood high-density lipoprotein (HDL).

CONCLUSIONS

Krill oil may lead to moderate improvement of cardiovascular risks, specifically endothelial dysfunction and HDL in patients with type 2 diabetes.

TRIAL REGISTRATION NUMBER

Registered with ClinicalTrials.gov: NCT02091193.

Therapeutic efficacy of bone marrow-derived mononuclear cells in diabetic polyneuropathy is impaired with aging or diabetes

Aims/Introduction

Recent studies have shown that cell transplantation therapies, such as endothelial precursor cells, bone marrow-derived mononuclear cells (BM-MNCs) and mesenchymal stem cells, are effective on diabetic polyneuropathy through ameliorating impaired nerve blood flow in diabetic rats. Here, we investigated the effects of BM-MNCs transplantation in diabetic polyneuropathy using BM-MNCs derived from adult (16-week-old) diabetic (AD), adult non-diabetic (AN) or young (8-week-old) non-diabetic (YN) rats.

Materials and Methods

BM-MNCs of AD and AN were isolated after an 8-week diabetes duration. The BM-MNCs were characterized using flow cytometry analysis of cell surface markers and reverse transcription polymerase chain reaction of several cytokines. BM-MNCs or saline were injected into hind limb muscles. Four weeks later, the thermal plantar test, nerve conduction velocity, blood flow of the sciatic nerve and capillary-to-muscle fiber ratio were evaluated.

Results

The number of CD29⁺/CD90⁺ cells that host mesenchymal stem cells in BM-MNCs decreased in AD compared with AN or YN, and transcript expressions of basic fibroblast growth factor and nerve growth factor in BM-MNCs decreased in AD compared with AN or YN. Impaired thermal sensation, decreased blood flow of the sciatic nerve and delayed nerve conduction velocity in 8-week-diabetic rats were significantly ameliorated by BM-MNCs derived from YN, whereas BM-MNCs from AD or AN rats did not show any beneficial effect in these functional tests.

Conclusions

These results show that cytokine production abilities and the mesenchymal stem cell population of BM-MNCs would be modified by aging and metabolic changes in diabetes, and that these differences could explain the disparity of the therapeutic efficacy of BM-MNCs between young and adult or diabetic and non-diabetic patients in diabetic polyneuropathy.

Characterization of circulating and endothelial progenitor cells in patients with extreme-duration type 1 diabetes

OBJECTIVE

We characterized and correlated endothelial progenitor cells (EPCs) and circulating progenitor cells (CPCs) with lack of vascular complications in the Joslin Medalist Study in patients with type 1 diabetes for 50 years or longer.

RESEARCH DESIGN AND METHODS

EPC and CPC levels were ascertained by flow cytometry and compared among Medalists (n = 172) with or without diabetic retinopathy (DR; n = 84 of 162), neuropathy (n = 94 of 165), diabetic nephropathy (DN; n = 18 of 172), cardiovascular disease (CVD; n = 63 of 168), age-matched controls (n = 83), type 2 diabetic patients (n = 36), and younger type 1 diabetic patients (n = 31). Mitogens, inflammatory cytokines, and oxidative markers were measured in blood or urine. Migration of cultured peripheral blood mononuclear cells (PBMCs) from Medalists and age-matched controls were compared.

RESULTS

Medalists' EPC and CPC levels equaled those of their nondiabetic age-matched controls, were 10% higher than those in younger type 1 diabetic patients, and were 20% higher than those in age-matched type 2 diabetic patients. CPC levels were 15% higher in Medalists without CVD and nephropathy than in those affected, whereas EPC levels were significantly higher in those without peripheral vascular disease (PVD) than those with PVD. Stromal-derived factor 1 (SDF-1) levels were higher in Medalists with CVD, DN, and DR than in those not affected and their controls. IGF-I levels were lower in Medalists and correlated inversely with CPC levels. Additionally, cultured PBMCs from Medalists migrated more than those from nondiabetic controls.

CONCLUSIONS

Normal levels of EPC and CPC in the Medalists, unlike other groups with diabetes, especially those without CVD, support the idea that endogenous factors exist to neutralize the adverse effects of metabolic abnormalities of diabetes on vascular tissues.

Isolation of a circulating CD45-, CD34dim cell population and validation of their endothelial phenotype

Accurately detecting circulating endothelial cells (CECs) is important since their enumeration has been proposed as a biomarker to measure injury to the vascular endothelium. However, there is no single methodology for determining CECs in blood, making comparison across studies difficult. Many methods for detecting CECs rely on characteristic cell surface markers and cell viability indicators, but lack secondary validation. Here, a CEC population in healthy adult human subjects was identified by flow cytometry as CD45-, CD34dim that is comparable to a previously described CD45-, CD31bright population. In addition, nuclear staining with 7-aminoactinomycin D (7-AAD) was employed as a standard technique to exclude dead cells. Unexpectedly, the CD45-, CD34dim, 7-AAD- CECs lacked surface detectable CD146, a commonly used marker of CECs. Furthermore, light microscopy revealed this cell population to be composed primarily of large cells without a clearly defined nucleus. Nevertheless, immunostains still demonstrated the presence of the lectin Ulex europaeus and von Willebrand factor. Ultramicro analytical immunochemistry assays for the endothelial cell proteins CD31, CD34, CD62E, CD105, CD141, CD144 and vWF indicated these cells possess an endothelial phenotype. However, only a small amount of RNA, which was mostly degraded, could be isolated from these cells. Thus the majority of CECs in healthy individuals as defined by CD45-, CD34dim, and 7-AAD- have shed their CD146 surface marker and are senescent cells without an identifiable nucleus and lacking RNA of sufficient quantity and quality for transcriptomal analysis. This study highlights the importance of secondary validation of CEC identification.

Endothelial progenitor cells in diabetic retinopathy

Diabetic retinopathy (DR) is a leading cause of visual impairment worldwide. Patients with DR may irreversibly lose sight as a result of the development of diabetic macular edema (DME) and/or proliferative diabetic retinopathy (PDR); retinal blood vessel dysfunction and degeneration plays an essential role in their pathogenesis. Although new treatments have been recently introduced for DME, including intravitreal vascular endothelial growth factor inhibitors (anti-VEGFs) and steroids, a high proportion of patients (~40-50%) do not respond to these therapies. Furthermore, for people with PDR, laser photocoagulation remains a mainstay therapy despite this being an inherently destructive procedure. Endothelial progenitor cells (EPCs) are a low-frequency population of circulating cells known to be recruited to sites of vessel damage and tissue ischemia where they promote vascular healing and re-perfusion. A growing body of evidence suggests that the number and function of EPCs are altered in patients with varying degrees of diabetes duration, metabolic control, and in the presence or absence of DR. Although there are no clear-cut outcomes from these clinical studies, there is mounting evidence that some EPC sub-types may be involved in the pathogenesis of DR and may also serve as biomarkers for disease progression and stratification. Moreover, some EPC sub-types have considerable potential as therapeutic modalities for DME and PDR in the context of cell therapy. This study presents basic clinical concepts of DR and combines this with a general insight on EPCs and their relation to future directions in understanding and treating this important diabetic complication.

Regulation of endothelial progenitor cell release by Wnt signaling in bone marrow

PURPOSE

Endothelial progenitor cells (EPC) have been shown to participate in ischemia-induced retinal neovascularization (NV). Overactivation of Wnt signaling has a pathogenic role in ischemia-induced retinal NV. The purpose of this study is to determine whether Wnt signaling regulates EPC release.

METHODS

Oxygen-induced retinopathy (OIR) was used as a model of retinal NV and Wnt pathway activation. The EPC, marked as c-Kit(+)/Tie-2(+) cells in the peripheral blood and bone marrow, were quantified using flow cytometry following immunolabeling. The Wnt signaling activity was evaluated by measuring nonphosphorylated β-catenin levels and X-gal staining in the Wnt reporter mice (Bat-gal mice).

RESULTS

The c-Kit(+)/Tie-2(+) cells were increased significantly in the peripheral blood and bone marrow of mice with OIR, compared to non-OIR mice. Overexpression of kallistatin, an endogenous inhibitor of the Wnt pathway, in kallistatin transgenic (kallistatin-TG) mice with OIR attenuated the increases of c-Kit(+)/Tie-2(+) cells in the peripheral blood and bone marrow, compared to WT mice with OIR. When the Bat-gal mice were crossed with kallistatin-TG mice, kallistatin overexpression suppressed the OIR-induced increases of X-gal-positive cells in the retinas and bone marrow, suggesting inhibition of Wnt signaling in these tissues. Furthermore, intraperitoneal injection of LiCl, a Wnt signaling activator, increased c-Kit(+)/Tie-2(+) cells in the peripheral blood of normal mice. Consistently, LiCl activated Wnt signaling in the retina and bone marrow cells in Bat-gal mice.

CONCLUSIONS

The Wnt signaling pathway has an important role in EPC release during retinal NV in OIR.

Personalized cytomic assessment of vascular health: Evaluation of the vascular health profile in diabetes mellitus

BACKGROUND

An inexpensive and accurate blood test does not currently exist that can evaluate the cardiovascular health of a patient. This study evaluated a novel high dimensional flow cytometry approach in combination with cytometric fingerprinting (CF), to comprehensively enumerate differentially expressed subsets of pro-angiogenic circulating progenitor cells (CPCs), involved in the repair of vasculature, and microparticles (MPs), frequently involved in inflammation and thrombosis. CF enabled discovery of a unique pattern, involving both MPs and CPCs and generated a personalized signature of vascular health, the vascular health profile (VHP).

METHODS

Levels of CPCs and MPs were measured with a broad panel of cell surface markers in a population with atherosclerosis and type 2 diabetes mellitus (DM) and age-similar Healthy controls (HC) using an unbiased computational approach, termed CF.

RESULTS

Circulating hematopoietic stem and progenitor cell (CHSPCAng) levels were detected at significantly lower concentrations in DM (P < 0.001), whereas levels of seven phenotypically distinct MPs were present at significantly higher concentrations in DM patients and one MP subset was present at significantly lower concentration in DM patients. Collectively, the combination of CHSPC(Ang) and MP levels was more informative than any one measure alone.

CONCLUSIONS

This work provides the basis for a personalized cytomic vascular health profile that may be useful for a variety of applications including drug development, clinical risk assessment and companion diagnostics.