Oxidative stress impairs endothelial progenitor cell function

14-3-3-η interacts with BCL-2 to protect human endothelial progenitor cells from ox-LDL-triggered damage

Oxidized low-density lipoprotein (ox-LDL) causes dysfunction of endothelial progenitor cells (EPCs), and we recently reported that 14-3-3-η can attenuate the damage triggered by ox-LDL in EPCs. However, the molecular mechanisms by which 14-3-3-η protects EPCs from the damage caused by ox-LDL are not fully understood. In this study, we observed that the expression of 14-3-3-η and BCL-2 were downregulated in ox-LDL-treated EPCs. Overexpression of 14-3-3-η in ox-LDL-treated EPC significantly increased BCL-2 level, while knockdown of BCL-2 reduced 14-3-3-η expression and mitigated the protective effect of 14-3-3-η on EPCs. In addition, we discovered that 14-3-3-η colocalizes and interacts with BCL-2 in EPCs. Taken together, these data suggest that 14-3-3-η protects EPCs from ox-LDL-induced damage by its interaction with BCL-2.

microRNAs as Biomarkers of Endothelial Dysfunction and Therapeutic Target in the Pathogenesis of Atrial Fibrillation

The pathophysiology of atrial fibrillation (AF) may involve atrial fibrosis/remodeling and dysfunctional endothelial activities. Despite the currently available treatment approaches, the progression of AF, its recurrence rate, and the high mortality risk of related complications underlay the need for more advanced prognostic and therapeutic strategies. There is increasing attention on the molecular mechanisms controlling AF onset and progression points to the complex cell to cell interplay that triggers fibroblasts, immune cells and myofibroblasts, enhancing atrial fibrosis. In this scenario, endothelial cell dysfunction (ED) might play an unexpected but significant role. microRNAs (miRNAs) regulate gene expression at the post-transcriptional level. In the cardiovascular compartment, both free circulating and exosomal miRNAs entail the control of plaque formation, lipid metabolism, inflammation and angiogenesis, cardiomyocyte growth and contractility, and even the maintenance of cardiac rhythm. Abnormal miRNAs levels may indicate the activation state of circulating cells, and thus represent a specific read-out of cardiac tissue changes. Although several unresolved questions still limit their clinical use, the ease of accessibility in biofluids and their prognostic and diagnostic properties make them novel and attractive biomarker candidates in AF. This article summarizes the most recent features of AF associated with miRNAs and relates them to potentially underlying mechanisms.

ZPI prevents ox-LDL-mediated endothelial injury leading to inhibition of EndMT, inflammation, apoptosis, and oxidative stress through activating Pi3k/Akt signal pathway

Oxidized low-density lipoprotein (ox-LDL)-mediated endothelial dysfunction exerts an essential role in the development of atherosclerosis. Protein Z-dependent protease inhibitor (ZPI), a member of the serine protease inhibitor superfamily, could inhibit the function of activated coagulation factor X (FXa) via interaction with protein Z (PZ). Studies have pointed out that ZPI was statistically related to atherosclerotic diseases, which may have a robust cardiovascular protective effect. However, the underlying mechanism of ZPI on ox-LDL-mediated endothelial injury requires further elucidation. Human umbilical vein endothelial cells (HUVECs) were treated with ox-LDL (100 μg/ml) and ZPI (10 μg/ml). Cell viability was measured by the Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis, oxidative stress, and endothelial-to-mesenchymal transition (EndMT) were analyzed by immunofluorescence (IF). Cell migration was measured using a wound-healing assay. Quantitative real-time polymerase chain reaction and western blot analysis were performed to determine messenger RNA and protein expression. Ox-LDL (100 μg/ml, 48 h) significantly reduced cell viability and migration, increased EndMT, inflammation, apoptosis, and oxidative stress. The related protein expression of phosphatidylinositol 3 kinase/protein kinase B (Pi3k/Akt) signal pathway in HUVECs was also simultaneously decreased. We also discovered that ZPI treatment could prevent ox-LDL-mediated endothelial injury through the improvement of cell viability and alleviation of apoptosis, oxidative stress, EndMT, and inflammation. Thus, the protective effect of ZPI on HUVECs may be mediated by activation of the Pi3k/Akt signal pathway. ZPI may exert an important protective role in HUVECs dysfunction triggered by ox-LDL via activation of the Pi3k/Akt signal pathway. Therefore, ZPI may possess potential therapeutic effects on atherosclerotic endothelial injury-related diseases.

Methacrylated gelatin shape-memorable cryogel subcutaneously delivers EPCs and aFGF for improved pressure ulcer repair in diabetic rat model

Pressure ulcer (PU) in patients with diabetes mellitus (DM) is still a clinical intractable issue due to the complicated physiological characteristics by the prolonged high glucose level and impaired angiogenesis. The PU treatment includes surgical debridement, stem cell therapy and growth factors, leading to high cost and repeated professional involvement. Developing effective wound dressing combining the therapeutic cells and growth factors has become highly demanded. Herein, we reported the direct subcutaneous administration of endothelial progenitor cells (EPCs) and acid fibroblast growth factor (aFGF) with a shape-memorable methacrylated gelatin cryogel (EPCs/aFGF@GelMA) for the therapy of PU in rats with DM. This EPCs/aFGF@GelMA cryogel system presented microporous structure, elastic mechanical strength and enhanced cell migration property with controlled release of aFGF. Moreover, compared with EPCs/aFGF and GelMA alone, in vivo results showed that this EPCs/aFGF@GelMA system exhibited accelerated wound closure rate, enhanced granulation formation, collagen deposition as well as re-epithelization. Importantly, we found that the excellent positive performance of EPCs/aFGF@GelMA is due to its up-regulation of HIF-ɑ upon the wound site, modulating the microenvironment of wound site to initiate the impaired local angiogenesis. Collectively, this hybrid gelatin cryogels show great promise for biomedical applications, especially in tissue engineering and regenerative medicine.

Outgrowth endothelial progenitor cells restore cerebral barrier function following ischaemic damage: the impact of NOX2 inhibition

Disruption of blood-brain barrier (BBB), formed mainly by human brain microvascular endothelial cells (HBMECs), constitutes the major cause of mortality following ischaemic stroke. This study investigates whether OECs (outgrowth endothelial cells) can restore BBB integrity and function following ischaemic damage, and how inhibition of NOX2, a main source of vascular oxidative stress, affects the characteristics of BBB established with OECs and HBMECs in ischaemic settings. In vitro models of human BBB were constructed by co-culture of pericytes and astrocytes with either OECs or HBMECs before exposure to oxygen-glucose deprivation (OGD) alone or followed by reperfusion (OGD+R) in the absence or presence of NOX2 inhibitor, gp91ds-tat. The function and integrity of BBB were assessed by measurements of paracellular flux of sodium fluorescein (NaF) and transendothelial electrical resistance (TEER), respectively. Treatment with OECs during OGD+R effectively restored BBB integrity and function. Compared to HBMECs, OECs possessed lower NADPH oxidase activity, superoxide anion levels, and had greater total antioxidant capacity during OGD and OGD+R. Inhibition of NADPH oxidase during OGD and OGD+R restored the integrity and function of BBB established by HBMECs. This was evidenced by reductions in NADPH oxidase activity and superoxide anion levels. In contrast, treatment with gp91ds-tat aggravated ischaemic injury-induced BBB damage constructed by OECs. In conclusion, OECs are more resistant to ischaemic conditions and can effectively repair cerebral barrier following ischaemic damage. Suppression of oxidative stress through specific targeting of NOX2 requires close attention while using OECs as therapeutics.

Effect of oral intake of royal jelly on endothelium function in hemodialysis patients: study protocol for multicenter, double-blind, randomized control trial

Background

Hemodialysis (HD) is a common renal replacement therapy for patients with renal failure. Cardiovascular and cerebrovascular diseases are known to shorten survival periods and worsen the quality of life of HD patients. Atherosclerosis is a major cause of vascular diseases, and various factors such as abnormality of lipid metabolism and increased macrophage activity, oxidative stress, and endothelial dysfunction are associated with its pathogenesis and progression. Further, endothelial stem cells (ESCs) have been reported to play important roles in endothelial functions. Royal jelly (RJ) affects atherosclerosis- and endothelial function-related factors. The main aim of this trial is to investigate whether oral intake of RJ can maintain endothelial function in HD patients. In addition, the effects of RJ intake on atherosclerosis, ESC count, inflammation, and oxidative stress will be analyzed.

Methods

This will be a multicenter, prospective, double-blind, randomized controlled trial. We will enroll 270 participants at Nagasaki Jin Hospital, Shinzato Clinic Urakami, and Maeda Clinic, Japan. The participants will be randomized into RJ and placebo groups. The trial will be conducted according to the principles of the Declaration of Helsinki, and all participants will be required to provide written informed consent. The RJ group will be treated with 3600 mg/day of RJ for 24 months, and the placebo group will be treated with starch for 24 months. The primary endpoint will be the change in flow-mediated dilation (FMD), a parameter of endothelium function, from the time before treatment initiation to 24 months after treatment initiation. The secondary and other endpoints will be changes in FMD; ESC count; serum levels of vascular endothelial cell growth factor, macrophage colony-stimulating factor, 8-hydroxydeoxyguanosine, and malondialdehyde; the incidence of cardiovascular diseases, cerebrovascular diseases, and stenosis of blood access; and safety.

Discussion

This trial will clarify whether oral intake of RJ can maintain endothelial function and suppress the progression of atherosclerosis in HD patients. In addition, it will clarify the effects of RJ on ESCs, oxidative stress, and angiogenic activity in blood samples.

Trial registration

The Japan Registry of Clinical Trials jRCTs071200031.  Registered on 7 December 2020.

N-acetyl cysteine ameliorates aortic fibrosis by promoting M2 macrophage polarization in aging mice

Background: Vascular fibrosis is a universal phenomenon associated with aging, and oxidative stress plays an important role in the genesis of vascular damage in line with the aging process. However, whether antioxidants can ameliorate vascular fibrosis remains unclear.

Objectives: The present study was to determine antioxidant N-acetylcysteine (NAC) could ameliorates aortic fibrosis in aging wild-type C57BL/6 mice.

Methods: The aortas were harvested from both 12-week and 60-week wild-type mice. The 60-week mice were treated with and without the NAC for 12 weeks starting at the age of 48 weeks. Hematoxylin and eosin (H&E) staining and Masson's trichrome staining of aortic samples were performed, and the levels of reactive oxygen species (ROS), RNA expression of GAPDH, TNF-α, MCP-1, IL-6, IL-10, IL-4, SIRT-1, SIRT-3, FOXO-1, and macrophage polarization were determined.

Results: There is a positive relationship between collagen deposition and the M1/M2 macrophage ratio in the aortic wall of aged wild-type C57BL/6 mice. The higher collagen area percentage in the aortas of 60-week-old mice than in 12-week-old mice was reversed by NAC. NAC could not impact the total number of macrophages, but partly promoted M2 macrophage polarization. By performing qRT-PCR using aortic samples from these mice, we identified that SIRT-1, SIRT-3, FOXO-1 could be somehow responsible for aging-related fibrosis.

Conclusions: NAC ameliorates aortic fibrosis in aging wild type mice partly by promoting M2 macrophage polarization.

Effective Actions of Ion Release from Mesoporous Bioactive Glass and Macrophage Mediators on the Differentiation of Osteoprogenitor and Endothelial Progenitor Cells

Due to their specific mesoporous structure and large surface area, mesoporous bioactive glasses (MBGs) possess both drug-delivery ability and effective ionic release to promote bone regeneration by stimulating osteogenesis and angiogenesis. Macrophages secrete mediators that can affect both processes, depending on their phenotype. In this work, the action of ion release from MBG-75S, with a molar composition of 75SiO₂-20CaO-5P₂O₅, on osteogenesis and angiogenesis and the modulatory role of macrophages have been assessed in vitro with MC3T3-E1 pre-osteoblasts and endothelial progenitor cells (EPCs) in monoculture and in coculture with RAW 264.7 macrophages. Ca²⁺, phosphorous, and silicon ions released from MBG-75S were measured in the culture medium during both differentiation processes. Alkaline phosphatase activity and matrix mineralization were quantified as the key markers of osteogenic differentiation in MC3T3-E1 cells. The expression of CD31, CD34, VEGFR2, eNOS, and vWF was evaluated to characterize the EPC differentiation into mature endothelial cells. Other cellular parameters analyzed included the cell size and complexity, intracellular calcium, and intracellular content of the reactive oxygen species. The results obtained indicate that the ions released by MBG-75S promote osteogenesis and angiogenesis in vitro, evidencing a macrophage inhibitory role in these processes and demonstrating the high potential of MBG-75S for the preparation of implants for bone regeneration.

Metabolic and Redox Regulation of Cardiovascular Stem Cell Biology and Pathology

Significance: Cardiovascular stem cells are important for regeneration and repair of damaged tissue. Recent Advances: Pluripotent stem cells have a unique metabolism, which is adopted for their energetic and biosynthetic demand as rapidly proliferating cells. Stem cell differentiation requires an exceptional metabolic flexibility allowing for metabolic remodeling between glycolysis and oxidative phosphorylation. Critical Issues: Respiration is associated with the generation of reactive oxygen species (ROS) by the mitochondrial respiratory chain. But also the membrane-bound protein nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase, NOX) contributes to ROS levels. ROS not only play a significant role in stem cell differentiation and tissue renewal but also cause senescence and contribute to tissue aging. Future Directions: For utilization of stem cells in therapeutic approaches, a deep understanding of the molecular mechanisms how metabolism and the cellular redox state regulate stem cell differentiation is required. Modulating the redox state of stem cells using antioxidative agents may be suitable to enhance activity of endothelial progenitor cells. Antioxid. Redox Signal. 35, 163-181.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

Tyrosine-Protein Phosphatase Non-receptor Type 9 (PTPN9) Negatively Regulates the Paracrine Vasoprotective Activity of Bone-Marrow Derived Pro-angiogenic Cells: Impact on Vascular Degeneration in Oxygen-Induced Retinopathy

Background and Aim

Insufficient post-ischemic neovascularization is an initial key step in the pathogenesis of Oxygen-Induced Retinopathy (OIR). During neovascularization, pro-angiogenic cells (PACs) are mobilized from the bone marrow and integrate into ischemic tissues to promote angiogenesis. However, the modulation of PAC paracrine activity during OIR and the specific mechanisms involved remain to be explored. Because Tyrosine-protein phosphatase non-receptor type 9 (PTPN9) is reported to be a negative regulator of stem cell differentiation and angiogenesis signaling, we investigated its effect on PAC activity in the context of OIR.

Methods and Results

In a rat model of OIR, higher levels of PTPN9 in the retina and in bone marrow derived PACs are associated with retinal avascular areas, lower levels of the mobilization factor SDF-1 and decreased number of CD34⁺/CD117⁺/CD133⁺ PACs. PACs exposed ex vivo to hyperoxia display increased PTPN9 expression, which is associated with impaired ability of PAC secretome to promote angiogenesis ex vivo (choroidal vascular sprouting) and in vitro (endothelial cell tubule formation) compared to the secretome of PACs maintained in normoxia. Suppression of PTPN9 (using siRNA) increases VEGF and SDF-1 expression to normalize PAC secretome during hyperoxia, leading to restored angiogenic ability of PAC secretome. Moreover, endothelial cells exposed to the secretome of siPTPN9-treated PACs expressed increased levels of activated form of VEGF receptor 2 (VEGFR2). In the rat model of OIR, intravitreal injection of secretome from siPTPN9-treated PACs significantly reduced retinal vaso-obliteration; this was associated with higher retinal levels of VEGF/SDF-1, and increased recruitment of PACs (CD34⁺ cells) to the retinal and choroidal vessels.

Conclusion

Our results suggest that hyperoxia alters the paracrine proangiogenic activity of BM-PACs by inducing PTPN9, which can contribute to impair post-ischemic revascularization in the context of OIR. Targeting PTPN9 restores PAC angiogenic properties, and provide a new target for vessel integrity in ischemic retinopathies.

Nephrotoxicity of Anti-Angiogenic Therapies

The use of inhibitors of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling for the treatment of cancer has increased over the last decade. This signaling pathway plays a fundamental role in angiogenesis and also in kidney physiology. The emergence of anti-angiogenic therapies has led to adverse nephrotoxic effects, despite improving the outcomes of patients. In this review, we will present the different anti-angiogenic therapies targeting the VEGFR pathway in association with the incidence of renal manifestations during their use. In addition, we will discuss, in detail, the pathophysiological mechanisms of frequent renal diseases such as hypertension, proteinuria, renal dysfunction, and electrolyte disorders. Finally, we will outline the cellular damage described following these therapies.

NOX4 is a major regulator of cord blood-derived endothelial colony-forming cells which promotes post-ischaemic revascularization

AIMS

Cord blood-derived endothelial colony-forming cells (CB-ECFCs) are a defined progenitor population with established roles in vascular homeostasis and angiogenesis, which possess low immunogenicity and high potential for allogeneic therapy and are highly sensitive to regulation by reactive oxygen species (ROS). The aim of this study was to define the precise role of the major ROS-producing enzyme, NOX4 NADPH oxidase, in CB-ECFC vasoreparative function.

METHODS AND RESULTS

In vitro CB-ECFC migration (scratch-wound assay) and tubulogenesis (tube length, branch number) was enhanced by phorbol 12-myristate 13-acetate (PMA)-induced superoxide in a NOX-dependent manner. CB-ECFCs highly-expressed NOX4, which was further induced by PMA, whilst NOX4 siRNA and plasmid overexpression reduced and potentiated in vitro function, respectively. Increased ROS generation in NOX4-overexpressing CB-ECFCs (DCF fluorescence, flow cytometry) was specifically reduced by superoxide dismutase, highlighting induction of ROS-specific signalling. Laser Doppler imaging of mouse ischaemic hindlimbs at 7 days indicated that NOX4-knockdown CB-ECFCs inhibited blood flow recovery, which was enhanced by NOX4-overexpressing CB-ECFCs. Tissue analysis at 14 days revealed consistent alterations in vascular density (lectin expression) and eNOS protein despite clearance of injected CB-ECFCs, suggesting NOX4-mediated modulation of host tissue. Indeed, proteome array analysis indicated that NOX4-knockdown CB-ECFCs largely suppressed tissue angiogenesis, whilst NOX4-overexpressing CB-ECFCs up-regulated a number of pro-angiogenic factors specifically-linked with eNOS signalling, in parallel with equivalent modulation of NOX-dependent ROS generation, suggesting that CB-ECFC NOX4 signalling may promote host vascular repair.

CONCLUSION

Taken together, these findings indicate a key role for NOX4 in CB-ECFCs, thereby highlighting its potential as a target for enhancing their reparative function through therapeutic priming to support creation of a pro-reparative microenvironment and effective post-ischaemic revascularization.

The Functionality of Endothelial-Colony-Forming Cells from Patients with Diabetes Mellitus

Endothelial-colony-forming cells (ECFCs) are a population of progenitor cells which have demonstrated promising angiogenic potential both in vitro and in vivo. However, ECFCs from diabetic patients have been shown to be dysfunctional compared to ECFCs from healthy donors. Diabetes mellitus itself presents with many vascular co-morbidities and it has been hypothesized that ECFCs may be a potential cell therapy option to promote revascularisation in these disorders. While an allogeneic cell therapy approach would offer the potential of an ‘off the shelf’ therapeutic product, to date little research has been carried out on umbilical cord-ECFCs in diabetic models. Alternatively, autologous cell therapy using peripheral blood-ECFCs allows the development of a personalised therapeutic approach to medicine; however, autologous diabetic ECFCs are dysfunctional and need to be repaired so they can effectively treat diabetic co-morbidities. Many different groups have modified autologous diabetic ECFCs to improve their function using a variety of methods including pre-treatment with different factors or with genetic modification. While the in vitro and in vivo data from the literature is promising, no ECFC therapy has proceeded to clinical trials to date, indicating that more research is needed for a potential ECFC therapy in the future to treat diabetic complications.

Enhanced Osseointegration and Bio-Decontamination of Nanostructured Titanium Based on Non-Thermal Atmospheric Pressure Plasma

Alkali-treated titanate layer with nanonetwork structures (TNS) is a promising surface for improving osseointegration capacity in implants. Nevertheless, there is a risk of device failure as a result of insufficient resistance to biofilm contamination. This study tested whether treatment using a handheld non-thermal plasma device could efficiently eliminate biofilm contamination without destroying the surface nanostructure while re-establishing a surface that promoted new bone generation. TNS specimens were treated by a piezoelectric direct discharge (PDD) plasma generator. The effect of decontamination was performed utilizing Staphylococcus aureus. The evaluation of initial cell attachment with adhesion images, alkaline phosphatase activity, extracellular matrix mineralization, and expression of genes related to osteogenesis was performed using rat bone marrow mesenchymal stem cells, and the bone response were evaluated in vivo using a rat femur model. Nanotopography and surface roughness did not significantly differ before and after plasma treatments. Cell and bone formation activity were improved by TNS plasma treatment. Furthermore, plasma treatment effectively eliminated biofilm contamination from the surface. These results suggested that this plasma treatment may be a promising approach for the treatment of nanomaterials immediately before implantation and a therapeutic strategy for peri-implantitis.

Revascularization and limb salvage following critical limb ischemia by nanoceria-induced Ref-1/APE1-dependent angiogenesis

In critical limb ischemia (CLI), overproduction of reactive oxygen species (ROS) and impairment of neovascularization contribute to muscle damage and limb loss. Cerium oxide nanoparticles (CNP, or 'nanoceria') possess oxygen-modulating properties which have shown therapeutic utility in various disease models. Here we show that CNP exhibit pro-angiogenic activity in a mouse hindlimb ischemia model, and investigate the molecular mechanism underlying the pro-angiogenic effect. CNP were injected into a ligated region of a femoral artery, and tissue reperfusion and hindlimb salvage were monitored for 3 weeks. Tissue analysis revealed stimulation of pro-angiogenic markers, maturation of blood vessels, and remodeling of muscle tissue following CNP administration. At a dose of 0.6 mg CNP, mice showed reperfusion of blood vessels in the hindlimb and a high rate of limb salvage (71%, n = 7), while all untreated mice (n = 7) suffered foot necrosis or limb loss. In vitro, CNP promoted endothelial cell tubule formation via the Ref-1/APE1 signaling pathway, and the involvement of this pathway in the CNP response was confirmed in vivo using immunocompetent and immunodeficient mice and by siRNA knockdown of APE1. These results demonstrate that CNP provide an effective treatment of CLI with excessive ROS by scavenging ROS to improve endothelial survival and by inducing Ref-1/APE1-dependent angiogenesis to revascularize an ischemic limb.

Activating α7nAChRs enhances endothelial progenitor cell function partially through the JAK2/STAT3 signaling pathway

Microvascular injury is a common pathological process in ischemia-reperfusion injury. Endothelial progenitor cells (EPCs) are vital cells for angiogenesis and endothelial repair. These cells can home to injury sites and secrete angiogenic growth factors. α7nAChRs are pivotal in cholinergic angiogenesis, which is associated with endothelial cells and EPCs. Our study was designed to determine whether activating α7nAChRs enhances the function of EPCs and to explore the underlying mechanism. EPCs were derived from the bone marrow of male Sprague-Dawley rats and treated with an α7nAChR agonist (PNU282987), an α7nAChR antagonist (MLA) and a JAK2 antagonist (AG490). We then assayed the angiogenic abilities of the EPCs, including proliferation ability, adhesion ability, migration ability and in vitro tube formation ability. The levels of total JAK2 (t-JAK2), phosphorylated JAK2 (p-JAK2), total STAT3 (t-STAT3) and phosphorylated STAT3 (p-STAT3) were estimated by western blot analysis. PNU282987 treatment facilitated the angiogenic abilities of EPCs compared with the control regimen. The western blot data suggested that PNU282987 increased the levels of p-JAK2 and p-STAT3. However, the differences in t-JAK2 levels and t-STAT3 levels between the agonist-treated group and the control group were not significant. Moreover, treating EPCs with AG490 reduced STAT3 phosphorylation and attenuated the PNU282987-induced enhancement of EPCs. We demonstrated that activating α7nAChRs can enhance EPC functions partially through the JAK2/STAT3 signaling pathway. This study reveals that α7nAChRs are potential therapeutic targets for angiogenesis and that the JAK2/STAT3 pathway plays a vital role in the associated therapeutic mechanism.

Natural Compounds as a Strategy to Optimize "In Vitro" Expansion of Stem Cells

The efficient use of stem cells for transplantation is often limited by the relatively low number of stem cells collected. The ex vivo expansion of human stem cells for clinical use is a potentially valuable approach to increase stem cell number. Currently, most of the procedures used to expand stem cells are carried out using a 21% oxygen concentration, which is about 4- to 10-fold greater than the concentration characteristic of their natural niches. Hyperoxia might cause oxidative stress with a deleterious effect on the physiology of cultured stem cells. In this review, we investigate and critically examine the available information on the ability of natural compounds to counteract hyperoxia-induced damage in different types of stem cells ex vivo. In particular, we focused on proliferation and stemness maintenance in an attempt to draw up useful indications to define new culture media with a promoting activity on cell expansion in vitro.

Therapeutic strategies for enhancing angiogenesis in wound healing

The enhancement of wound healing has been a goal of medical practitioners for thousands of years. The development of chronic, non-healing wounds is a persistent medical problem that drives patient morbidity and increases healthcare costs. A key aspect of many non-healing wounds is the reduced presence of vessel growth through the process of angiogenesis. This review surveys the creation of new treatments for healing cutaneous wounds through therapeutic angiogenesis. In particular, we discuss the challenges and advancement that have been made in delivering biologic, pharmaceutical and cell-based therapies as enhancers of wound vascularity and healing.

Heart Failure With Preserved Ejection Fraction: A Review of Cardiac and Noncardiac Pathophysiology

Heart failure with preserved ejection fraction (HFpEF) is one of the largest unmet clinical needs in 21st-century cardiology. It is a complex disorder resulting from the influence of several comorbidities on the endothelium. A derangement in nitric oxide bioavailability leads to an intricate web of physiological abnormalities in the heart, blood vessels, and other organs. In this review, we examine the contribution of cardiac and noncardiac factors to the development of HFpEF. We zoom in on recent insights on the role of comorbidities and microRNAs in HFpEF. Finally, we address the potential of exercise training, which is currently the only available therapy to improve aerobic capacity and quality of life in HFpEF patients. Unraveling the underlying mechanisms responsible for this improvement could lead to new biomarkers and therapeutic targets for HFpEF.

Concomitant overexpression of triple antioxidant enzymes selectively increases circulating endothelial progenitor cells in mice with limb ischaemia

Endothelial progenitor cells (EPCs) are a group of heterogeneous cells in bone marrow (BM) and blood. Ischaemia increases reactive oxygen species (ROS) production that regulates EPC number and function. The present study was conducted to determine if ischaemia‐induced ROS differentially regulated individual EPC subpopulations using a mouse model concomitantly overexpressing superoxide dismutase (SOD)1, SOD3 and glutathione peroxidase. Limb ischaemia was induced by femoral artery ligation in male transgenic mice with their wild‐type littermate as control. BM and blood cells were collected for EPCs analysis and mononuclear cell intracellular ROS production, apoptosis and proliferation at baseline, day 3 and day 21 after ischaemia. Cells positive for c‐Kit⁺/CD31⁺ or Sca‐1⁺/Flk‐1⁺ or CD34⁺/CD133⁺ or CD34⁺/Flk‐1⁺ were identified as EPCs. ischaemia significantly increased ROS production and cell apoptosis and decreased proliferation of circulating and BM mononuclear cells and increased BM and circulating EPCs levels. Overexpression of triple antioxidant enzymes effectively prevented ischaemia‐induced ROS production with significantly decreased cell apoptosis and preserved proliferation and significantly increased circulating EPCs level without significant changes in BM EPC populations, associated with enhanced recovery of blood flow and function of the ischemic limb. These data suggested that ischaemia‐induced ROS was differentially involved in the regulation of circulating EPC population.

The vasoreparative potential of endothelial colony-forming cells in the ischemic retina is enhanced by cibinetide, a non-hematopoietic erythropoietin mimetic

PURPOSE

Retinal ischemia remains a common sight threatening end-point in blinding diseases such as diabetic retinopathy and retinopathy of prematurity. Endothelial colony forming cells (ECFCs) represent a subpopulation of endothelial progenitors with therapeutic utility for promoting reparative angiogenesis in the ischaemic retina. The current study has investigated the potential of enhancing this cell therapy approach by the dampening of the pro-inflammatory milieu typical of ischemic retina. Based on recent findings that ARA290 (cibinetide), a peptide based on the Helix-B domain of erythropoietin (EPO), is anti-inflammatory and tissue-protective, the effect of this peptide on ECFC-mediated vascular regeneration was studied in the ischemic retina.

METHODS

The effects of ARA290 on pro-survival signaling and function were assessed in ECFC cultures in vitro. Efficacy of ECFC transplantation therapy to promote retinal vascular repair in the presence and absence of ARA290 was studied in the oxygen induced retinopathy (OIR) model of retinal ischemia. The inflammatory cytokine profile and microglial activation were studied as readouts of inflammation.

RESULTS

ARA290 activated pro-survival signaling and enhanced cell viability in response to H₂O₂-mediated oxidative stress in ECFCs in vitro. Preconditioning of ECFCs with EPO or ARA290 prior to delivery to the ischemic retina did not enhance vasoreparative function. ARA290 delivered systemically to OIR mice reduced pro-inflammatory expression of IL-1β and TNF-α in the mouse retina. Following intravitreal transplantation, ECFCs incorporated into the damaged retinal vasculature and significantly reduced avascular area. The vasoreparative function of ECFCs was enhanced in the presence of ARA290 but not EPO.

DISCUSSION

Regulation of the pro-inflammatory milieu of the ischemic retina can be enhanced by ARA290 and may be a useful adjunct to ECFC-based cell therapy for ischemic retinopathies.

Protective Role of Endogenous Kallistatin in Vascular Injury and Senescence by Inhibiting Oxidative Stress and Inflammation

Kallistatin was identified in human plasma as a tissue kallikrein-binding protein and a serine proteinase inhibitor. Kallistatin exerts pleiotropic effects on angiogenesis, oxidative stress, inflammation, apoptosis, fibrosis, and tumor growth. Kallistatin levels are markedly reduced in patients with coronary artery disease, sepsis, diabetic retinopathy, inflammatory bowel disease, pneumonia, and cancer. Moreover, plasma kallistatin levels are positively associated with leukocyte telomere length in young African Americans, indicating the involvement of kallistatin in aging. In addition, kallistatin treatment promotes vascular repair by increasing the migration and function of endothelial progenitor cells (EPCs). Kallistatin via its heparin-binding site antagonizes TNF-α-induced senescence and superoxide formation, while kallistatin's active site is essential for inhibiting miR-34a synthesis, thus elevating sirtuin 1 (SIRT1)/eNOS synthesis in EPCs. Kallistatin inhibits oxidative stress-induced cellular senescence by upregulating Let-7g synthesis, leading to modulate Let-7g-mediated miR-34a-SIRT1-eNOS signaling pathway in human endothelial cells. Exogenous kallistatin administration attenuates vascular injury and senescence in association with increased SIRT1 and eNOS levels and reduced miR-34a synthesis and NADPH oxidase activity, as well as TNF-α and ICAM-1 expression in the aortas of streptozotocin- (STZ-) induced diabetic mice. Conversely, endothelial-specific depletion of kallistatin aggravates vascular senescence, oxidative stress, and inflammation, with further reduction of Let-7g, SIRT1, and eNOS and elevation of miR-34a in mouse lung endothelial cells. Furthermore, systemic depletion of kallistatin exacerbates aortic injury, senescence, NADPH oxidase activity, and inflammatory gene expression in STZ-induced diabetic mice. These findings indicate that endogenous kallistatin displays a novel role in protection against vascular injury and senescence by inhibiting oxidative stress and inflammation.

Increased circulating endothelial progenitor cells and improved short-term outcomes in acute non-cardioembolic stroke after hyperbaric oxygen therapy

Background

Acute ischemic stroke is a leading cause of mortality and long-term disability, and profiles of endothelial progenitor cells (EPCs) reflect the degree of endothelial impairment. This study tested the hypothesis that hyperbaric oxygen therapy (HBOT) both improves the clinical short-term outcomes and increases the number of circulating EPCs and antioxidant capacity.

Methods

The numbers of circulating EPCs [CD133⁺/CD34⁺ (%), KDR⁺/CD34⁺ (%)], biomarkers for oxidative stress (thiols and thiobarbituric acid-reactive substances), and clinical scores (National Institutes of Health Stroke Scale [NIHSS], Barthel index [BI], and modified Rankin Scale [MRS]) were prospectively evaluated in 25 patients with acute non-cardioembolic stroke under HBOT at two time points (pre- and post-HBOT). The biomarkers and clinical scores were compared with those of 25 age- and sex-matched disease controls.

Results

The numbers of KDR⁺/CD34⁺ (%) in the HBOT group following HBOT increased significantly, whereas the numbers of CD133⁺/CD34⁺ (%) also showed a tendency to increase without statistical significance. The mean high-sensitivity C-reactive protein levels showed significant decrease post-HBOT follow-up in the HBOT group. The changes in KDR⁺/CD34⁺EPC (%) numbers were positively correlated with changes in clinical outcomes scores (BI, NIHSS, and MRS) in the HBOT group.

Conclusions

Based on the results of our study, HBOT can both improve short-term clinical outcomes and increase the number of circulating EPCs in patients with acute non-cardioembolic stroke.

Drug-Free ROS Sponge Polymeric Microspheres Reduce Tissue Damage from Ischemic and Mechanical Injury

The inherent antioxidant function of poly(propylene sulfide) (PPS) microspheres (MS) was dissected for different reactive oxygen species (ROS), and therapeutic benefits of PPS-MS were explored in models of diabetic peripheral arterial disease (PAD) and mechanically induced post-traumatic osteoarthritis (PTOA). PPS-MS (∼1 μm diameter) significantly scavenged hydrogen peroxide (H2O2), hypochlorite, and peroxynitrite but not superoxide in vitro in cell-free and cell-based assays. Elevated ROS levels (specifically H2O2) were confirmed in both a mouse model of diabetic PAD and in a mouse model of PTOA, with greater than 5- and 2-fold increases in H2O2, respectively. PPS-MS treatment functionally improved recovery from hind limb ischemia based on ∼15-25% increases in hemoglobin saturation and perfusion in the footpads as well as earlier remodeling of vessels in the proximal limb. In the PTOA model, PPS-MS reduced matrix metalloproteinase (MMP) activity by 30% and mitigated the resultant articular cartilage damage. These results suggest that local delivery of PPS-MS at sites of injury-induced inflammation improves the vascular response to ischemic injury in the setting of chronic hyperglycemia and reduces articular cartilage destruction following joint trauma. These results motivate further exploration of PPS as a stand-alone, locally sustained antioxidant therapy and as a material for microsphere-based, sustained local drug delivery to inflamed tissues at risk of ROS damage.

Arginine administration increases circulating endothelial progenitor cells and attenuates tissue injury in a mouse model of hind limb ischemia/reperfusion

OBJECTIVE

This study investigated whether the administration of L-Arginine, the precursor of nitric oxide, increases the percentages of blood endothelial progenitor cells and protects against ischemia/reperfusion induced inflammatory response in a mouse model of hind-limb IR injury.

METHOD

C57BL/6 mice were randomized to one normal-control and four ischemia/reperfusion groups. The normal-control group did not undergo an ischemia/reperfusion procedure but mice in the ischemia/reperfusion groups were subjected to 150 min of unilateral hind-limb ischemia. The ischemia/reperfusion groups were subjected to either intravenous saline or L-Arginine (300 mg/kg body weight) administration before reperfusion and then sacrificed at either 24 h or 48 h after reperfusion. Blood and muscle tissues were collected for analysis.

RESULTS

Ischemia/reperfusion injury led to a significant decrease in the percentage of blood endothelial progenitor cells and plasma nitric oxide concentration but plasma interleukin-6 levels and gene expression of inflammatory cytokines in injured muscle tissue were elevated. In contrast to the saline groups, those with L-Arginine administration were able to maintain a normal level of blood endothelial progenitor cells. In addition, after reperfusion, concentrations of nitric oxide, matrix metallopeptidase-9, and vascular endothelial growth factor in plasma were upregulated but keratinocyte-derived chemokine and monocyte chemoattractant protein-1 messenger RNA expressions in muscle were attenuated 48 h after reperfusion. Histologic findings also demonstrated a significant reduction of ischemia/reperfusion-induced muscle injury when L-Arginine was administered.

CONCLUSION

A single dose of L-Arginine administration before reperfusion increases the percentage of endothelial progenitor cells and reduces the inflammatory reaction locally and systemically after ischemia/reperfusion injury.

Highly efficient local delivery of endothelial progenitor cells significantly potentiates angiogenesis and full-thickness wound healing

Wound therapy with a rapid healing performance remains a critical clinical challenge. Cellular delivery is considered to be a promising approach to improve the efficiency of healing, yet problems such as compromised cell viability and functionality arise due to the inefficient delivery. Here, we report the efficient delivery of endothelial progenitor cells (EPCs) with a bioactive nanofibrous scaffold (composed of collagen and polycaprolactone and bioactive glass nanoparticles, CPB) for enhancing wound healing. Under the stimulation of CPB nanofibrous system, the viability and angiogenic ability of EPCs were significantly enhanced through the activation of Hif-1α/VEGF/SDF-1α signaling. In vivo, CPB/EPC constructs significantly enhanced the formation of high-density blood vessels by greatly upregulating the expressions of Hif-1α, VEGF, and SDF-1α. Moreover, owing to the increased local delivery of cells and fast neovascularization within the wound site, cell proliferative activity, granulation tissue formation, and collagen synthesis and deposition were greatly promoted by CPB/EPC constructs resulting in rapid re-epithelialization and regeneration of skin appendages. As a result, the synergistic enhancement of wound healing was observed from CPB/EPC constructs, which suggests the highly efficient delivery of EPCs. CPB/EPC constructs may become highly competitive cell-based therapeutic products for efficient impaired wound healing application. This study may also provide a novel strategy to develop bioactive cell therapy constructs for angiogenesis-related regenerative medicine.

STATEMENT OF SIGNIFICANCE

This paper reported a highly efficient local delivery of EPCs using bioactive glass-based CPB nanofibrous scaffold for enhancing angiogenesis and wound regeneration. In vitro study showed that CPB can promote the proliferation, migration, and tube formation of EPCs through upregulation of the Hif-1α/VEGF/SDF-1α signaling pathway, indicating that the bioactivity and angiogenic ability of EPCs can be highly maintained and promoted by the CPB scaffold. Moreover, CPB/EPC constructs effectively stimulated the regeneration of diabetic wounds with satisfactory vascularization and better healing outcomes in a full-thickness wound model, suggesting that the highly efficient delivery of EPCs to wound site facilitates angiogenesis and further leads to wound healing. The high angiogenic capacity and excellent healing ability make CPB/EPC constructs highly competitive in cell-based therapeutic products for efficient wound repair application.

Differences in the neovascular potential of thymus versus subcutaneous adipose-derived stem cells from patients with myocardial ischaemia

Adipose tissue-derived multipotent mesenchymal cells (ASCs) participate in the information of blood vessels under hypoxic conditions. It is probable that the susceptibility of ASCs to the influence of age and ageing-associated pathologies compromises their therapeutic effectiveness depending on the adipose tissue depot. Our aim was to examine the neovascular potential under hypoxic conditions of ASCs-derived from thymic (thymASCs) and subcutaneous (subASCs) adipose tissue from 39 subjects with and without type 2 diabetes mellitus (T2DM) and of different ages who were undergoing coronary bypass surgery. We confirmed a significant decrease in the percentage of CD34⁺ CD31^- CD45^- subASCs in the cell yield of subASCs and in the survival of cultured endothelial cells in the medium conditioned by the hypox-subASCs with increasing patient age, which was not observed in thymASCs. Whereas the length of the tubules generated by hypox-subASCs tended to correlate negatively with patient age, tubule formation capacity of the hypoxic thymASCs increased significantly. Compared with subASCs, thymASCs from subjects over age 65 and without T2DM showed higher cell yield, tubule formation capacity, vascular endothelial growth factor secretion levels, and ability to promote endothelial cell survival in their conditioned medium. Deterioration in subASCs neovascular potential relative to thymASCs derived from these subjects was accompanied by higher expression levels of NOX4 mRNA and fibrotic proteins. Our results indicate that thymASCs from patients over age 65 and without T2DM have a higher angiogenic potential than those from the other patient groups, suggesting they may be a good candidate for angiogenic therapy in subjects undergoing coronary bypass surgery.

Accelerated decline in cardiac stem cell efficiency in Spontaneously hypertensive rat compared to normotensive Wistar rat

Cardiac hypertrophy is recognized as an independent risk factor for cardiac failure. Efficient management of hypertensive heart disease requires identification of factors that can possibly mediate the transition from hypertrophy to failure. Resident cardiac stem cells have a prominent role in the maintenance of cardiac tissue homeostasis. Decline in the proportion of healthy cardiac stem cells (CSCs) can affect tissue regeneration. In pathological conditions, apart from natural aging, an adverse microenvironment can lead to decrease in efficiency of CSCs. A systematic analysis of cardiac stem cell characteristics in pathological conditions has not been reported so far. Therefore, this study was designed with the objective of examining the age associated variation in stem cell attributes of Spontaneously hypertensive rat (SHR) in comparison with normotensive Wistar rat. Spontaneously hypertensive rat was used as the experimental model since the cardiac remodeling resembles the clinical course of hypertensive heart disease. CSCs were isolated from atrial explants. Stem cell attributes were assessed in 1-week, 6, 12 and 18-month-old male SHR, in comparison with age matched Wistar rats. In 1-week-old pups, stem cell attributes of SHR and Wistar were comparable. Migration potential, proliferative capacity, TERT expression, telomerase activity and the proportion of c-kit⁺ cells decreased with age, both in SHR and Wistar. DNA damage and the proportion of senescent CSCs increased with age both in SHR and Wistar rats. Age associated increase was observed in the oxidative stress of stem cells, possibly mediated by the enhanced oxidative stress in the microenvironment. The changes were more pronounced in SHR, and as early as six months of age, there was significant decrease in efficiency of CSCs of SHR compared to Wistar. The density of healthy CSCs determined as a fraction of the differentiated cells was remarkably low in 18-month-old SHR. Age associated decrease in functionally efficient CSCs was therefore accelerated in SHR. Considering the vital role of CSCs in the maintenance of a healthy myocardium, decrease in functionally efficient CSCs can be a precipitating factor in pathological cardiac remodeling. Elevated ROS levels in CSCs of SHR lends scope for speculation that decrease in efficiency of CSCs is mediated by oxidative stress; and that modulation of the microenvironment by therapeutic interventions can restore a healthy stem cell population and facilitate maintenance of cardiac homeostasis and prevent cardiac decompensation.

Different response to hypoxia of adipose-derived multipotent cells from obese subjects with and without metabolic syndrome

Background/Objectives

Multiple studies suggest that hypoxia, together with inflammation, could be one of the phenomena involved in the onset and progression of obesity-related insulin resistance. In addition, dysfunction of adipose tissue in obese subjects with metabolic syndrome is associated with decreased angiogenesis. However, some subjects with a high body mass index do not develop metabolic abnormalities associated with obesity. The aim of the current study was to examine the neovascular properties of visceral adipose tissue-derived multipotent mesenchymal cells subjected to hypoxia (hypox-visASCs) from normal-weight subjects (Nw) and obese patients with metabolic syndrome (MS) and without metabolic syndrome (NonMS).

Methods

This was a 2-year study to enroll subjects who underwent bariatric surgery or cholecystectomy. Eight patients who underwent either bariatric surgery or cholecystectomy (27 patients) participated in the study. Visceral adipose tissue samples from Nw, MS and NonMS subjects were processed by enzymatic digestion. VisASCs cultured under hypoxic conditions were characterized by tubule formation assay, ELISA, flow cytometry, migration rate, and qRT-PCR, and the effects of visASCs-conditioned medium on survival and endothelial cell tubule formation were evaluated.

Results

Hypox-visASCs from NonMS subjects showed a greater capacity for tubule formation than hypox-visASCs from Nw and MS subjects. The lower percentage of CD140b⁺/CD44⁺ and CD140b⁺/CD184⁺ cells observed in hypox-visASCs from NonMS subjects compared to MS subjects was accompanied not only by a lower migration rate from the chemotactic effects of stromal cell derived factor 1α, but also by lower levels of NOX5 mRNA expression. While the levels of monocyte chemoattractant protein 1 mRNA expressed by hypox-visASCs correlated positively with the body mass index and waist circumference of the subjects, the concentration of vascular endothelial growth factor present in hypox-visASC-conditioned culture medium decreased significantly with increasing plasma glucose. The survival rate and tubules formed by endothelial cells cultured in hypox-visASC-conditioned medium decreased significantly with increasing homeostasis model assessment to quantify insulin resistance.

Conclusions

Our results suggest that hypox-visASCs from NonMS subjects could promote healthy adipose tissue expansion, while hypox-visASCs from MS subjects appear to contribute to the decreased angiogenic potential and increased inflammation underlying adipose tissue dysfunction in obesity. Our results emphasize the importance of taking into account not only the BMI but also the metabolic profile of the subjects during the implementation of ASCs-based therapy to promote neovascularization.

Histamine-2 receptor antagonist famotidine modulates cardiac stem cell characteristics in hypertensive heart disease

BACKGROUND

Cardiac stem cells (CSCs) play a vital role in cardiac homeostasis. A decrease in the efficiency of cardiac stem cells is speculated in various cardiac abnormalities. The maintenance of a healthy stem cell population is essential for the prevention of adverse cardiac remodeling leading to cardiac failure. Famotidine, a histamine-2 receptor antagonist, is currently used to treat ulcers of the stomach and intestines. In repurposing the use of the drug, reduction of cardiac hypertrophy and improvement in cardiac function of spontaneously hypertensive rats (SHR) was reported by our group. Given that stem cells are affected in cardiac pathologies, the effect of histamine-2 receptor antagonism on CSC characteristics was investigated.

METHODS

To examine whether famotidine has a positive effect on CSCs, spontaneously hypertensive rats (SHR) treated with the drug were sacrificed; and CSCs isolated from atrial appendages was evaluated. Six-month-old male SHRs were treated with famotidine (30 mg/kg/day) for two months. The effect of famotidine treatment on migration, proliferation and survival of CSCs was compared with untreated SHRs and normotensive Wistar rats.

RESULTS

Functional efficiency of CSCs from SHR was compromised relative to that in Wistar rat. Famotidine increased the migration and proliferation potential, along with retention of stemness of CSCs in treated SHRs. Cellular senescence and oxidative stress were also reduced. The expression of H2R was unaffected by the treatment.

DISCUSSION

As anticipated, CSCs from SHRs were functionally impaired. Stem cell attributes of famotidine-treated SHRs was comparable to that of Wistar rats. Therefore, in addition to being cardioprotective, the histamine 2 receptor antagonist modulated cardiac stem cells characteristics. Restoration of stem cell efficiency by famotidine is possibly mediated by reduction of oxidative stress as the expression of H2R was unaffected by the treatment. Maintenance of healthy stem cell population is suggested as a possible mechanism underlying the cardioprotective effect of famotidine.

Yoder M, Majluf-Cruz A, Alvarado-Moreno JA. Reduced proliferation of endothelial colony-forming cells in unprovoked venous thromboembolic disease as a consequence of endothelial dysfunction

BACKGROUND

Venous thromboembolic disease (VTD) is a public health problem. We recently reported that endothelial colony-forming cells (ECFCs) derived from endothelial cells (EC) (ECFC-ECs) from patients with VTD have a dysfunctional state. For this study, we proposed that a dysfunctional status of these cells generates a reduction of its proliferative ability, which is also associated with senescence and reactive oxygen species (ROS).

METHODS AND RESULTS

Human mononuclear cells (MNCs) were obtained from peripheral blood from 40 healthy human volunteers (controls) and 50 patients with VTD matched by age (20-50 years) and sex to obtain ECFCs. We assayed their proliferative ability with plasma of patients and controls and supernatants of cultures from ECFC-ECs, senescence-associated β-galactosidase (SA-β-gal), ROS, and expression of ephrin-B2/Eph-B4 receptor. Compared with cells from controls, cells from VTD patients showed an 8-fold increase of ECFCs that emerged 1 week earlier, reduced proliferation at long term (39%) and, in passages 4 and 10, a highly senescent rate (30±1.05% vs. 91.3±15.07%, respectively) with an increase of ROS and impaired expression of ephrin-B2/Eph-4 genes. Proliferation potential of cells from VTD patients was reduced in endothelial medium [1.4±0.22 doubling population (DP)], control plasma (1.18±0.31 DP), or plasma from VTD patients (1.65±0.27 DP).

CONCLUSIONS

As compared with controls, ECFC-ECs from individuals with VTD have higher oxidative stress, proliferation stress, cellular senescence, and low proliferative potential. These findings suggest that patients with a history of VTD are ECFC-ECs dysfunctional that could be associated to permanent risk for new thrombotic events.

Bevacizumab-induced hypertension: Clinical presentation and molecular understanding

Bevacizumab is a vascular endothelial growth factor-A-specific angiogenesis inhibitor indicated as an adjunct to chemotherapy for the treatment of several types of cancer. Hypertension is commonly observed during bevacizumab treatment, and high-grade toxicity can limit therapy and lead to other cardiovascular complications. The factors that contribute to interindividual variability in blood pressure response to bevacizumab treatment are not well understood. In this review, we outline research efforts to understand the mechanisms and pathophysiology of hypertension resulting from bevacizumab treatment. Moreover, we highlight current knowledge of the pharmacogenetics of bevacizumab-induced hypertension, which may be used to develop strategies to prevent or minimize this toxicity.

Neovascular deterioration, impaired NADPH oxidase and inflammatory cytokine expression in adipose-derived multipotent cells from subjects with metabolic syndrome

OBJECTIVE

Expansion of adipose tissue depends on the growth of its vascular network and it has been shown that adipose tissue dysfunction in obese subjects with the metabolic syndrome is associated with decreased angiogenesis. However, some subjects with a high body mass index do not develop metabolic abnormalities associated with obesity. In this study we examined the neovascular properties, expression levels of proteins involved in cellular redox balance and inflammatory cytokines in adipose-derived multipotent mesenchymal cells (ASCs) of subjects with different metabolic profiles.

MATERIALS/METHODS

We applied cell culture, flow cytometry, RT-qPCR and ELISA techniques to characterize the ASCs isolated from paired biopsies of visceral (visASCs) and subcutaneous (subASCs) adipose tissue from 39 subjects grouped into normal weight (Nw), obese without metabolic syndrome (NonMS) and with metabolic syndrome (MS).

RESULTS

VisASCs and subASCs from MS subjects showed a decrease in tubules formation capacity compared to ASCs from NonMS subjects as well as changes in the expression levels of proteins involved in cell redox balance and secretion levels of proteins linked to the senescence-associated secretory phenotype. Deterioration in the neovascular properties of subASCs from the MS subjects was also evident in the decreased levels of VEGF secretion during adipogenesis and in the effects of the conditioned medium on endothelial cell tubule formation.

CONCLUSIONS

Our findings suggest a redox imbalance status in ASCs from subjects with metabolic syndrome and decreased their neovascular function that probably contributes to the vascular insufficiency of adipose depots.

The Transcription Factor Nrf2 Protects Angiogenic Capacity of Endothelial Colony-Forming Cells in High-Oxygen Radical Stress Conditions

Background

Endothelial colony forming cells (ECFCs) have shown a promise in tissue engineering of vascular constructs, where they act as endothelial progenitor cells. After implantation, ECFCs are likely to be subjected to elevated reactive oxygen species (ROS). The transcription factor Nrf2 regulates the expression of antioxidant enzymes in response to ROS.

Methods

Stable knockdown of Nrf2 and Keap1 was achieved by transduction with lentiviral shRNAs; activation of Nrf2 was induced by incubation with sulforaphane (SFN). Expression of Nrf2 target genes was assessed by qPCR, oxidative stress was assessed using CM-DCFDA, and angiogenesis was quantified by scratch-wound and tubule-formation assays Results. Nrf2 knockdown led to a reduction of antioxidant gene expression and increased ROS. Angiogenesis was disturbed after Nrf2 knockdown even in the absence of ROS. Conversely, angiogenesis was preserved in high ROS conditions after knockdown of Keap1. Preincubation of ECFCs with SFN reduced intracellular ROS in the presence of H₂O₂ and preserved scratch-wound closure and tubule-formation.

Results

Nrf2 knockdown led to a reduction of antioxidant gene expression and increased ROS. Angiogenesis was disturbed after Nrf2 knockdown even in the absence of ROS. Conversely, angiogenesis was preserved in high ROS conditions after knockdown of Keap1. Preincubation of ECFCs with SFN reduced intracellular ROS in the presence of H₂O₂ and preserved scratch-wound closure and tubule-formation.

Conclusion

The results of this study indicate that Nrf2 plays an important role in the angiogenic capacity of ECFCs, particularly under conditions of increased oxidative stress. Pretreatment of ECFCs with SFN prior to implantation may be a protective strategy for tissue-engineered constructs or cell therapies.

Number and function of circulating endothelial progenitor cells in patients with primary Budd-Chiari syndrome

BACKGROUND AND AIM

Primary Budd-Chiari syndrome (BCS) is associated with vascular endothelial injury. Circulating endothelial progenitor cells (EPCs) provide an endogenous mechanism to repair endothelial injury. This study investigated the levels and functionality of EPCs in patients with primary BCS.

METHODS

EPCs (CD34⁺/CD133⁺/KDR⁺) were quantified in 82 patients with primary BCS (inferior vena cava type: n=19; hepatic vein type: n=22; and mixed type: n=41), 10 cirrhosis controls (CC group) and 10 age-matched healthy controls (HC group), using flow cytometry. EPCs proliferation was detected by MTT assay, adhesion by adhesion activity assay, and migration capacity by Transwell assay.

RESULTS

EPCs levels were significantly lower in the BCS group (0.020±0.005%) than in the CC and HC groups (0.260±0.201%, 0.038±0.007%; P<0.001 for each). EPCs cultured in vitro from BCS and CC groups had, respectively, lower proliferation activity (0.20±0.04, 0.23±0.06 vs 0.58±0.07, each P<0.001), adhesion activity (15.8±1.7, 18.2±4.3 vs 35.0±2.5 cells/random microscopic field (RMF), each P<0.001) and migration activity (16.1±1.5, 16.7±3.0 vs 23.9±2.0 cells/RMF, each P<0.001) than in the HC group. EPCs functionality did not significantly differ between the BCS and CC groups. The numbers and functions of EPCs did not significantly differ among patients with inferior vena cava type, hepatic vein type and mixed type of BCS.

CONCLUSION

Patients with primary BCS had lower EPCs levels, with less proliferation, adhesion and migration activities. These findings suggest that lower levels of less functional EPCs may be associated with venous occlusion in primary BCS patients.

Antiproliferation effect of the uremic toxin para‑cresol on endothelial progenitor cells is related to its antioxidant activity

Endothelial dysfunction and impaired endothelial regenerative capacity are key contributors to the high incidence of cardiovascular disease in patients with chronic kidney disease (CKD). Uremic toxins are associated with this pathogenesis. Previous studies have revealed that a uremic toxin, para-cresol (p-cresol), exerts an antiproliferation effect on human endothelial progenitor cells (EPCs), but the mechanism remains unclear. In the present study, reactive oxygen species (ROS) were confirmed to function as signaling molecules that regulate growth factor-dependent EPC proliferation. EPCs were treated with p-cresol for 72 h, using a concentration range typically found in CKD patients. ROS production was analyzed by fluorescence microscopy and flow cytometry, and protein expression levels of nicotinamide adenine dinucleotide phosphate oxidase, a major source of ROS, were analyzed by western blot analysis. mRNA expression levels of antioxidant genes were assessed by reverse transcription-quantitative polymerase chain reaction analysis. The results revealed that p-cresol partially inhibits ROS production, and this effect may be associated with a significant reduction in cytochrome b-245 alpha and beta chain expression in EPCs. An increase of glutathione peroxidase 4 mRNA expression was also detected. In conclusion, the present study revealed that the antiproliferation effect of p-cresol on EPCs might act via its antioxidant activity. The results of the present study may facilitate understanding of uremic toxin toxicity on the cardiovascular system.

Dietary glutamine supplementation enhances endothelial progenitor cell mobilization in streptozotocin-induced diabetic mice subjected to limb ischemia

Diabetes is a metabolic disorder with increased risk of vascular diseases. Tissue ischemia may occur with diabetic vascular complications. Bone marrow-derived endothelial progenitor cells (EPCs) constitute a reparative response to ischemic injury. This study investigated the effects of oral glutamine (GLN) supplementation on circulating EPC mobilization and expression of tissue EPC-releasing markers in diabetic mice subjected to limb ischemia. Diabetes was induced by a daily intraperitoneal injection of streptozotocin for 5 days. Diabetic mice were divided into 2 nonischemic groups and 6 ischemic groups. One of the nonischemic and 3 ischemic groups were fed the control diet, while the remaining 4 groups received diets with identical components except that part of the casein was replaced by GLN. The respective diets were fed to the mice for 3 weeks, and then the nonischemic mice were sacrificed. Unilateral hindlimb ischemia was created in the ischemic groups, and mice were sacrificed at 1, 7 or 21 days after ischemia. Their blood and ischemic muscle tissues were collected for further analyses. Results showed that plasma matrix metallopeptidase (MMP)-9 and the circulating EPC percentage increased after limb ischemia in a diabetic condition. Compared to groups without GLN, GLN supplementation up-regulated plasma stromal cell-derived factor (SDF)-1 and muscle MMP-9, SDF-1, hypoxia-inducible factor-1 and vascular endothelial growth factor gene expression. The CD31-immunoreactive intensities were also higher in the ischemic limb. These findings suggest that GLN supplementation enhanced circulating EPC mobilization that may promote endothelium repair at ischemic tissue in diabetic mice subjected to limb ischemia.

Association Between Autonomic Impairment and Structural Deficit in Parkinson Disease

Patients with Parkinson disease (PD) have impaired autonomic function and altered brain structure. This study aimed to evaluate the relationship of gray matter volume (GMV) determined by voxel-based morphometry (VBM) to autonomic impairment in patients with PD. Whole-brain VBM analysis was performed on 3-dimensional T1-weighted images in 23 patients with PD and 15 sex- and age-matched healthy volunteers. The relationship of cardiovascular autonomic function (determined by survey) to baroreflex sensitivity (BRS) (determined from changes in heart rate and blood pressure during the early phase II of the Valsalva maneuver) was tested using least-squares regression analysis. The differences in GMV, autonomic parameters, and clinical data were correlated after adjusting for age and sex. Compared with controls, patients with PD had low BRS, suggesting worse cardiovascular autonomic function, and smaller GMV in several brain locations, including the right amygdala, left hippocampal formation, bilateral insular cortex, bilateral caudate nucleus, bilateral cerebellum, right fusiform, and left middle frontal gyri. The decreased GMVs of the selected brain regions were also associated with increased presence of epithelial progenitor cells (EPCs) in the circulation. In patients with PD, decrease in cardiovascular autonomic function and increase in circulating EPC level are associated with smaller GMV in several areas of the brain. Because of its possible role in the modulation of the circulatory EPC pool and baroreflex control, the left hippocampal formation may be a bio-target for disease-modifying therapy and treatment monitoring in PD.

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.

Porous polymer scaffold for on-site delivery of stem cells--Protects from oxidative stress and potentiates wound tissue repair

Wound healing by cell transplantation techniques often suffer setbacks due to oxidative stress encountered at injury sites. A porous polyethyleneglycol-polyurethane (PEG-PU) scaffold that facilitates cell delivery and boosts tissue repair was developed through semi-interpenetrating polymer network approach. The key physico-chemical properties assessed confirms these polymeric matrices are highly thermostable, barostable, degrade at an acidic pH (5.8), biodegradable, cytocompatible and possess excellent porosity. Mechanism of cellular penetration into porous polymer networks was evident by a ≥6 - fold increase in gene expression of MMP-13 and MMP-2 via activation of Akt and Erk. H2O2-induced apoptosis of mouse bone marrow stem cells (BMSCs) was abrogated in presence of polymer networks indicating a protective effect from oxidative stress. Transplantation of BMSC + PEG-PU at murine excisional splint wound site depicted significant increase in fibroblast proliferation, collagen deposition, anti-oxidant enzyme activities of catalase, SOD and GPx. Furthermore it significantly decreased expression of pro-inflammatory cytokines (IL-1β, TNF-α, IL-8, etc) with a concomitant increase in anti-inflammatory cytokines (IL-10, IL-13) at an early healing period of day 7. Finally, immunostaining revealed an enhanced engraftment and vascularity indicating an accelerated wound tissue closure. This pre-clinical study demonstrates the proof-of-concept and further necessitates their clinical evaluation as potential cell delivery vehicle scaffolds.

Vascular Repair by Tissue-Resident Endothelial Progenitor Cells in Endotoxin-Induced Lung Injury

Vascular disruption is one of the pathological hallmarks in acute respiratory distress syndrome. Bone marrow (BM)-derived circulating endothelial progenitor cells (EPCs) and lung tissue-resident EPCs have been considered to play a pivotal role in pulmonary vascular repair; however, which population is predominant in local pulmonary vasculogenesis remains to be clarified. We therefore examined the origin of EPCs participating in the regenerative process of pulmonary vascular endothelial cells (PVECs) in experimental acute respiratory distress syndrome. Lung samples from mice administered LPS intratracheally were investigated for cell dynamics and EPC functions. Quantitative flow cytometric analysis demonstrated that the number of PVECs decreased by roughly 20% on Day 1 and then recovered on Day 7 of LPS challenge. Bromodeoxyuridine-incorporation assays and immunofluorescence microscopy demonstrated that proliferating PVECs preferentially located in the capillary vessels. Experiments using BM chimera mice revealed that most of the regenerating PVECs were tissue-resident cells, and BM-derived cells hardly engrafted as PVECs. The population of circulating putative phenotypical EPCs decreased during the first week after LPS challenge. The regenerating PVECs were characterized by high colony-forming and vasculogenic capacities, intracellular reactive oxygen species scavenging and aldehyde dehydrogenase activites, and enhanced gene expression of Abcb1b (a drug-resistant gene), suggesting that the population of PVECs included tissue-resident EPCs activated during regenerative process of PVECs. The proliferating PVECs expressed CD34, Flk-1/KDR, and c-kit more strongly and Prom1/CD133 less strongly on the surface than nonproliferating PVECs. Our findings indicated that lung tissue-resident EPCs predominantly contribute to pulmonary vascular repair after endotoxin-induced injury.

Intervention Effect of Electroacupuncture Combined with EPCs Transplantation on the Mice in Aging Model

The results of this experiment suggested that electroacupuncture promotes the endothelialization of liver endothelial progenitor cells (EPCs) for mice in D-gal model and improves the repair of vascular endothelial function, as well as increasing the vascular endothelial growth factor (VEGF) expression in liver tissue fluorescence and KL protein levels. Also, it reduces the malondialdehyde (MDA) activity and delays vascular aging and even overall aging. Results showed that the in vivo fluorescence intensity for D-gal EA group was significantly lower than that of D-gal group, P < 0.05; VEGF fluorescence expression in liver tissue for D-gal EA group was significantly higher than that for D-gal group, P < 0.05; KL protein content in liver tissue for D-gal EA group was significantly higher than that for D-gal group, P < 0.05; MDA activity for D-gal EA group was significantly lower than that for D-gal group, P < 0.05.

Increased circulating endothelial progenitor cells and anti-oxidant capacity in obstructive sleep apnea after surgical treatment

BACKGROUND

Obstructive sleep apnea (OSA) has increased risk of cardiovascular diseases. Profiles of endothelial progenitor cells (EPCs) reflect the degree of endothelial impairment. This study tested the hypothesis that surgical treatment not only improves clinical outcomes but also increases the number of circulating EPCs and antioxidant capacity.

METHODS

The number of circulating EPCs (CD133(+)/CD34(+) [%], KDR(+)/CD34(+) [%]), biomarkers for oxidative stress (thiols and TBARS), and polysomnography (PSG) study was prospectively evaluated in 62 OSA patients at two time points (pre-operative and at least 3-month post-operative). The biomarkers and PSG were compared with those of 31 age- and body mass index (BMI)-matched healthy controls.

RESULTS

Levels of HbA1c and LDL-C were significantly higher while CD133(+)/CD34(+) (%) and HDL were significantly lower in OSA patients than in healthy controls. The levels of CD133(+)/CD34(+) (%) and thiols significantly increased in both mild/moderate and severe OSA. The TBAR levels also significantly decreased in severe OSA patients after >3months of follow-up. The number of CD133(+)/CD34(+) (%) negatively correlated with both age and mO2 of <90% but positively correlated with thiols. Clinical efficiency after OSA surgery assessed by PSG showed improvement and mean systolic blood pressure (SBP) (night and morning) reduction and improved lipid profile in the severe OSA group while only the snoring index improved in the mild/moderate OSA group.

CONCLUSIONS

OSA surgery not only improves clinical outcomes, SBP reduction and improved lipid profile but also increases the number of circulating EPCs and antioxidant capacity, especially in patients with severe OSA.

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.

Glutathione peroxidase-1 is required for self-renewal of murine embryonic stem cells

Embryonic stem (ES) cells are pluripotent cells that are capable of giving rise to any type of cells in the body and possess unlimited self-renewal potential. However, the exact regulatory mechanisms that govern the self-renewal ability of ES cells remain elusive. To understand the immediate early events during ES cell differentiation, we performed a proteomics study and analyzed the proteomic difference in murine ES cells before and after a 6-h spontaneous differentiation. We found that the expression level of glutathione peroxidase-1 (GPx-1), an antioxidant enzyme, is dramatically decreased upon the differentiation. Both knockdown of GPx-1 expression with shRNA and inhibiting GPx-1 activity by inhibitor led to the differentiation of ES cells. Furthermore, we showed that during early differentiation, the quick degradation of GPx-1 was mediated by proteasome. Thus, our data indicated that GPx-1 is a key regulator of self-renewal of murine embryonic stem cells.

Oxidative stress during extracorporeal circulation

There is an increased oxidative stress response in patients having cardiac surgery, haemodialysis or extracorporeal membrane oxygenation that is related to poorer outcomes and increased mortality. Exposure of the patients' blood to the artificial surfaces of these extracorporeal devices, coupled with inflammatory responses, hyperoxia and the pathophysiological aspects of the underlying illness itself, all contribute to this oxidative stress response. Oxidative stress occurs when there is a disruption of redox signalling and loss of control of redox balance. Ongoing oxidative stress occurring during extracorporeal circulation (ECC) results in damage to lipids, proteins and DNA and contributes to morbidity and mortality. This review discusses reactive species generation and the potential clinical consequences of oxidative stress during ECC as well as provides an overview of some current antioxidant compounds that are available to potentially mitigate the oxidative stress response.

Hypertension during vascular endothelial growth factor inhibition: focus on nitric oxide, endothelin-1, and oxidative stress

SIGNIFICANCE

Angiogenesis inhibition with humanized antibodies targeting vascular endothelial growth factor (VEGF) or orally active small tyrosine kinase inhibitors targeting VEGF receptors has become an established treatment modality for various forms of cancer. A common side effect of angiogenesis inhibition is the development of sometimes severe hypertension, which simultaneously appears to be predictive for a favorable antitumor response.

RECENT ADVANCES

Since VEGF increases the expression and activity of endothelial nitric oxide synthase, it has been assumed that the mean blood pressure (MAP) rise during angiogenesis inhibition is caused by a decrease in nitric oxide bioavailability. Yet, the results from experimental and clinical studies exploring this possibility are conflicting. Recent studies provided evidence that the MAP rise during angiogenesis inhibition rather is mediated by activation of the endothelin-1 (ET-1) axis, which, among others, induces oxidative stress. Nevertheless, conclusive evidence for the involvement of reactive oxygen species in the MAP rise could not be obtained so far.

CRITICAL ISSUES

The mechanism underlying activation of the ET-1 axis during angiogenesis inhibition is unclear, and this activation was not anticipated in view of studies showing that VEGF stimulates both the expression and production of ET-1 by endothelial cells.

FUTURE DIRECTIONS

In fact, this activation of the ET-1 axis may support the use of ET receptor antagonists for the treatment of angiogenesis inhibition-induced hypertension, especially because ET receptor stimulation in vascular smooth muscle cells results in VEGF production and mitogenesis in a mitogen-activated protein kinase pathway-dependent manner.