Involvement of E-selectin in recruitment of endothelial progenitor cells and angiogenesis in ischemic muscle

E-selectin in vascular pathophysiology

Selectins are a group of Ca2+-dependent, transmembrane type I glycoproteins which attract cell adhesion and migration. E-selectin is exclusively expressed in endothelial cells, and its expression is strongly enhanced upon activation by pro-inflammatory cytokines. The interaction of E-selectin with its ligands on circulating leukocytes captures and slows them down, further facilitating integrin activation, firm adhesion to endothelial cells and transmigration to tissues. Oxidative stress induces endothelial cell injury, leading to aberrant expression of E-selectin. In addition, the elevated level of E-selectin is positively related to high risk of inflammation. Dysregulation of E-selectin has been found in several pathological conditions including acute kidney injury (AKI), pulmonary diseases, hepatic pathology, Venous thromboembolism (VTE). Deletion of the E-selectin gene in mice somewhat ameliorates these complications. In this review, we describe the mechanisms regulating E-selectin expression, the interaction of E-selectin with its ligands, the E-selectin physiological and pathophysiological roles, and the therapeutical potential of targeting E-selectin.

Extracellular Vesicles in Metabolic and Vascular Insulin Resistance

BACKGROUND

Insulin resistance is a major etiological factor in obesity, type 2 diabetes, and cardiovascular disease (CVD). Endothelial dysfunction may precede impairments in insulin-stimulated glucose uptake, thereby making it a key feature in development of CVD. However, the mechanism by which vascular tissue becomes dysfunctional is not clear.

SUMMARY

Extracellular vesicles (EVs) have emerged as potential mediators of insulin resistance and vascular dysfunction. EVs are membrane-bound particles released by tissues following cellular stress or activation. They carry "cargo" (e.g., insulin signaling proteins, eNOS-nitric oxide, and miRNA) that are believed to promote inter-cellular and interorgan communications. Herein, we review the underlying physiology of EVs in relation to type 2 diabetes and CVD risk. Specifically, we discuss how EVs may modulate metabolic (e.g., skeletal muscle, liver, and adipose) insulin sensitivity, and propose that EVs may modulate vascular insulin action to influence both endothelial function and arterial stiffness. We lastly identify how EVs may play a unique role following exercise to promote metabolic and vascular insulin sensitivity changes.

KEY MESSAGE

Gaining insight toward insulin-mediated EV mechanism has potential to identify novel pathways regulating cardiometabolic health and provide foundation for examining EVs as unique biomarkers and targets to prevent and/or treat chronic diseases.

Buffalo bbu-miR-493-5p Promotes Myoblast Proliferation and Differentiation

In recent years, the meat and dairy value of buffaloes has become a major concern in buffalo breeding, and the improvement of buffalo beef quality is key to protecting buffalo germplasm resources and solving the problem of beef supply. MiRNAs play a significant role in regulating muscle development. However, the precise mechanism by which they regulate the development of buffalo skeletal muscles remains largely unexplored. In this study, we examined miRNA expression profiles in buffalo myoblasts during the proliferation and differentiation stages. A total of 177 differentially expressed miRNAs were identified, out of which 88 were up-regulated and 89 down-regulated. We focused on a novel miRNA, named bbu-miR-493-5p, that was significantly differentially expressed during the proliferation and differentiation of buffalo myoblasts and highly expressed in muscle tissues. The RNA-FISH results showed that bbu-miR-493-5p was primarily located in the cytoplasm to encourage buffalo myoblasts' proliferation and differentiation. In conclusion, our study lays the groundwork for future research into the regulatory role of miRNAs in the growth of buffalo muscle.

Endothelial progenitor cells in pregnancy-related diseases

Placental neovascularization plays a crucial role in fetomaternal circulation throughout pregnancy and is dysregulated in several pregnancy-related diseases, including preeclampsia, gestational diabetes mellitus, and fetal growth restriction. Endothelial progenitor cells (EPCs) are a heterogeneous population of cells that differentiate into mature endothelial cells, which influence vascular homeostasis, neovascularization, and endothelial repair. Since their discovery in 1997 by Asahara et al., the role of EPCs in vascular biology has garnered a lot of interest. However, although pregnancy-related conditions are associated with changes in the number and function of EPCs, the reported findings are conflicting. This review discusses the discovery, isolation, and classification of EPCs and highlights discrepancies between current studies. Overviews of how various diseases affect the numbers and functions of EPCs, the role of EPCs as biomarkers of pregnancy disorders, and the potential therapeutic applications involving EPCs are also provided.

Systemwide effects of ER-intracellular membrane contact site disturbance in primary endothelial cells

Membrane contact sites (MCS) make up a crucial route of inter-organelle non-vesicular transport within the cell. Multiple proteins are involved in this process, which includes the ER-resident proteins vesicle associated membrane protein associated protein A and -B (VAPA/B) that form MCS between the ER and other membrane compartments. Currently most functional data on VAP depleted phenotypes have shown alterations in lipid homeostasis, induction of ER stress, dysfunction of UPR and autophagy, as well as neurodegeneration. Literature on concurrent silencing of VAPA/B is still sparse; therefore, we investigated how it affects the macromolecule pools of primary endothelial cells. Our transcriptomics results showed significant upregulation in genes related to inflammation, ER and Golgi dysfunction, ER stress, cell adhesion, as well as Coat Protein Complex-I and -II (COP-I, COP-II) vesicle transport. Genes related to cellular division were downregulated, as well as key genes of lipid and sterol biosynthesis. Lipidomics analyses revealed reductions in cholesteryl esters, very long chain highly unsaturated and saturated lipids, whereas increases in free cholesterol and relatively short chain unsaturated lipids were evident. Furthermore, the knockdown resulted in an inhibition of angiogenesis in vitro. We speculate that ER MCS depletion has led to multifaceted outcomes, which include elevated ER free cholesterol content and ER stress, alterations in lipid metabolism, ER-Golgi function and vesicle transport, which have led to a reduction in angiogenesis. The silencing also induced an inflammatory response, consistent with upregulation of markers of early atherogenesis. To conclude, ER MCS mediated by VAPA/B play a crucial role in maintaining cholesterol traffic and sustain normal endothelial functions.

Epicatechin gallate promotes vascularization in co-culture of human osteoblasts and outgrowth endothelial cells

Prevascularization is crucial for the survival of tissue-engineered bone and further bone repair/regeneration. Since epicatechin gallate (ECG), the most abundant flavanol in green tea, shows potential beneficial effects on endothelial cells and bone cells, we decided to investigate whether it promotes vascularization/angiogenesis and osteogenesis using a co-culture system containing human primary osteoblasts (POBs) and outgrowth endothelial cells (OECs). We found that treatment with ECG (1) significantly enhanced microvessel formation in co-culture of POB and OECs, (2) improved cell viability/proliferation and the angiogenic/osteogenic capacities of OEC/POBs, (3) significantly increased the levels of E-selectin, IL-6, TNF-α, IFN-γ, VEGF, and PDGF-BB in co-cultures of POB and OEC, and (4) upregulated HIF-1α, HIF-2α, NF-κB, iNOS, GLUT1, VEGF, and Ang1/2 but downregulated PHD1 in monocultures of OEC or POB. Our findings demonstrate that ECG promotes angiogenesis and osteogenesis (probably via HIF signaling) in co-cultures of OECs and POBs. ECG thus has potential applications in the promotion of angiogenesis/vascularization in many tissue constructs including those of bone.

Molecular machineries of ciliogenesis, cell survival, and vasculogenesis are differentially expressed during regeneration in explants of the demosponge Halichondria panicea

Sponges are interesting animal models for regeneration studies, since even from dissociated cells, they are able to regenerate completely. In particular, explants are model systems that can be applied to many sponge species, since small fragments of sponges can regenerate all elements of the adult, including the oscula and the ability to pump water. The morphological aspects of regeneration in sponges are relatively well known, but the molecular machinery is only now starting to be elucidated for some sponge species. Here, we have used an explant system of the demosponge Halichondria panicea to understand the molecular machinery deployed during regeneration of the aquiferous system. We sequenced the transcriptomes of four replicates of the 5-day explant without an osculum (NOE), four replicates of the 17-18-day explant with a single osculum and pumping activity (PE) and also four replicates of field-collected individuals with regular pumping activity (PA), and performed differential gene expression analysis. We also described the morphology of NOE and PE samples using light and electron microscopy. Our results showed a highly disorganised mesohyl and disarranged aquiferous system in NOE that is coupled with upregulated pathways of ciliogenesis, organisation of the ECM, and cell proliferation and survival. Once the osculum is formed, genes involved in "response to stimulus in other organisms" were upregulated. Interestingly, the main molecular machinery of vasculogenesis described in vertebrates was activated during the regeneration of the aquiferous system. Notably, vasculogenesis markers were upregulated when the tissue was disorganised and about to start forming canals (NOE) and angiogenic stimulators and ECM remodelling machineries were differentially expressed once the aquiferous system was in place (PE and PA). Our results are fundamental to better understanding the molecular mechanisms involved in the formation of the aquiferous system in sponges, and its similarities with the early onset of blood-vessel formation in animal evolution.

E-Selectin/AAV2/2 Gene Therapy Alters Angiogenesis and Inflammatory Gene Profiles in Mouse Gangrene Model

For patients with chronic limb-threatening ischemia and limited revascularization options, alternate means for therapeutic angiogenesis and limb salvage are needed. E-selectin is a cell adhesion molecule that is critical for inflammation and neovascularization in areas of wound healing and ischemia. Here, we tested the efficacy of modifying ischemic limb tissue by intramuscular administration of E-selectin/AAV2/2 (adeno-associated virus serotype 2/2) to modulate angiogenic and inflammatory responses in a murine hindlimb gangrene model. Limb appearance, reperfusion, and functional recovery were assessed for 3 weeks after induction of ischemia. Mice receiving E-selectin/AAV2/2 gene therapy had reduced gangrene severity, increased limb and footpad perfusion, enhanced recruitment of endothelial progenitor cells, and improved performance on treadmill testing compared to control group. Histologically, E-selectin/AAV2/2 gene therapy was associated with increased vascularity and preserved myofiber integrity. E-selectin/AAV2/2 gene therapy also upregulated a panel of pro-angiogenic genes yet downregulated another group of genes associated with the inflammatory response. This novel gene therapy did not induce adverse effects on coagulability, or hematologic, hepatic, and renal function. Our findings highlight the potential of E-selectin/AAV2/2 gene therapy for improving limb perfusion and function in patients with chronic limb-threatening ischemia.

Homing of mRNA-Modified Endothelial Progenitor Cells to Inflamed Endothelium

Endothelial progenitor cells (EPCs) are one of the most important stem cells for the neovascularization of tissues damaged by ischemic diseases such as myocardial infarction, ischemic stroke, or critical limb ischemia. However, their low homing efficiency in the treatment of ischemic tissues limits their potential clinical applications. The use of synthetic messenger RNA (mRNA) for cell engineering represents a novel and promising technology for the modulation of cell behavior and tissue regeneration. To improve the therapeutic potential of EPCs, in this study, murine EPCs were engineered with synthetic mRNAs encoding C-X-C chemokine receptor 4 (CXCR4) and P-selectin glycoprotein ligand 1 (PSGL-1) to increase the homing and migration efficiency of EPCs to inflamed endothelium. Flow cytometric measurements revealed that the transfection of EPCs with CXCR4 and PSGL-1 mRNA resulted in increased expressions of CXCR4 and PSGL-1 on the cell surface compared with the unmodified EPCs. The transfection of EPCs with mRNAs did not affect cell viability. CXCR4-mRNA-modified EPCs showed significantly higher migration potential than unmodified cells in a chemotactic migration assay. The binding strength of the EPCs to inflamed endothelium was determined with single-cell atomic force microscopy (AFM). This showed that the mRNA-modified EPCs required a three-fold higher detachment force to be released from the TNF-α-activated endothelium than unmodified EPCs. Furthermore, in a dynamic flow model, significantly increased binding of the mRNA-modified EPCs to inflamed endothelium was detected. This study showed that the engineering of EPCs with homing factors encoding synthetic mRNAs increases the homing and migration potentials of these stem cells to inflamed endothelium. Thus, this strategy represents a promising strategy to increase the therapeutic potential of EPCs for the treatment of ischemic tissues.

Delivery of therapeutic agents and cells to pancreatic islets: Towards a new era in the treatment of diabetes

Pancreatic islet cells, and in particular insulin-producing beta cells, are centrally involved in the pathogenesis of diabetes mellitus. These cells are of paramount importance for the endocrine control of glycemia and glucose metabolism. In Type 1 Diabetes, islet beta cells are lost due to an autoimmune attack. In Type 2 Diabetes, beta cells become dysfunctional and insufficient to counterbalance insulin resistance in peripheral tissues. Therapeutic agents have been developed to support the function of islet cells, as well as to inhibit deleterious immune responses and inflammation. Most of these agents have undesired effects due to systemic administration and off-target effects. Typically, only a small fraction of therapeutic agent reaches the desired niche in the pancreas. Because islets and their beta cells are scattered throughout the pancreas, access to the niche is limited. Targeted delivery to pancreatic islets could dramatically improve the therapeutic effect, lower the dose requirements, and lower the side effects of agents administered systemically. Targeted delivery is especially relevant for those therapeutics for which the manufacturing is difficult and costly, such as cells, exosomes, and microvesicles. Along with therapeutic agents, imaging reagents intended to quantify the beta cell mass could benefit from targeted delivery. Several methods have been developed to improve the delivery of agents to pancreatic islets. Intra-arterial administration in the pancreatic artery is a promising surgical approach, but it has inherent risks. Targeted delivery strategies have been developed based on ligands for cell surface molecules specific to islet cells or inflamed vascular endothelial cells. Delivery methods range from nanocarriers and vectors to deliver pharmacological agents to viral and non-viral vectors for the delivery of genetic constructs. Several strategies demonstrated enhanced therapeutic effects in diabetes with lower amounts of therapeutic agents and lower off-target side effects. Microvesicles, exosomes, polymer-based vectors, and nanocarriers are gaining popularity for targeted delivery. Notably, liposomes, lipid-assisted nanocarriers, and cationic polymers can be bioengineered to be immune-evasive, and their advantages to transport cargos into target cells make them appealing for pancreatic islet-targeted delivery. Viral vectors have become prominent tools for targeted gene delivery. In this review, we discuss the latest strategies for targeted delivery of therapeutic agents and imaging reagents to pancreatic islet cells.

Therapeutic angiogenesis in Buerger's disease: reviewing the treatment landscape

Thromboangiitis obliterans, also known as Buerger's disease, is a rare inflammatory vasculitis that predominantly develops in smokers and characteristically affects the small- and medium-sized peripheral arteries and veins. Patients typically present with extremity claudication, but symptoms may progress to rest pain and tissue loss, especially in those unable to abstain from tobacco use. Unfortunately, traditional medical treatments are largely ineffective and due to the small caliber of affected vessels and lack of suitable distal targets or venous conduits, endovascular and open surgical approaches are often not possible. Eventually, a significant number of patients require major amputation. For these reasons, much research effort has been made in developing techniques of therapeutic angiogenesis to improve limb perfusion, both for atherosclerotic peripheral arterial disease and the smaller subset of patients with critical limb ischemia due to Buerger's disease. Neovascularization in response to ischemia relies on a complex interplay between the local tissue microenvironment and circulating stem and progenitor cells. To date, studies of therapeutic angiogenesis have therefore focused on exploiting known angiogenic factors and stem cells to induce neovascularization in ischemic tissues. This review summarizes the available clinical data regarding the safety and efficacy of various angiogenic therapies, notably injection of naked DNA plasmids, viral gene constructs, and cell-based preparations, and describes techniques for potentiating in vivo efficacy of gene- and cell-based therapies as well as ongoing developments in exosome-based cell-free approaches for therapeutic angiogenesis.

Plain Language Title and Summary

A review of available and emerging treatments for improving blood flow and wound healing in patients with Buerger's disease, a rare disorder of blood vessels Buerger's disease is a rare disorder of the small- and medium-sized blood vessels in the arms and legs that almost exclusively develops in young smokers. Buerger's disease causes inflammation in arteries and veins, which leads to blockage of these vessels and reduces blood flow to and from the extremities. Decreased blood flow to the arms and legs can lead to development of nonhealing wounds and infection for which some patients may eventually require amputation. Unfortunately, traditional medical and surgical treatments are not effective in Buerger's disease, so other methods for improving blood flow are needed for these patients. There are several different ways to stimulate new blood vessel formation, both in humans and animal models. The most common treatments involve injection of DNA or viruses that express genes related to blood vessel formation or, alternatively, stem cell-based treatments that help regenerate blood vessels and repair wound tissue. This review explores how safe and effective these various treatments are and describes recent research developments that may lead to better therapies for patients with Buerger's disease and other vascular disorders.

Role of Stromal Cell-Derived Factor-1 in Endothelial Progenitor Cell-Mediated Vascular Repair and Regeneration

Endothelial progenitor cells (EPCs) are immature endothelial cells that participate in vascular repair and postnatal neovascularization and provide a novel and promising therapy for the treatment of vascular disease. Studies in different animal models have shown that EPC mobilization through pharmacological agents and autologous EPC transplantation contribute to restoring blood supply and tissue regeneration after ischemic injury. However, these effects of the progenitor cells in clinical studies exhibit mixed results. The therapeutic efficacy of EPCs is closely associated with the number of the progenitor cells recruited into ischemic regions and their functional abilities and survival in injury tissues. In this review, we discussed the regulating role of stromal cell-derived factor-1 (also known CXCL12, SDF-1) in EPC mobilization, recruitment, homing, vascular repair and neovascularization, and analyzed the underlying machemisms of these functions. Application of SDF-1 to improve the regenerative function of EPCs following vascular injury was also discussed. SDF-1 plays a crucial role in mobilizing EPC from bone marrow into peripheral circulation, recruiting the progenitor cells to target tissue and protecting against cell death under pathological conditions; thus improve EPC regenerative capacity. SDF-1 are crucial for regulating EPC regenerative function, and provide a potential target for improve therapeutic efficacy of the progenitor cells in treatment of vascular disease.

The glycocalyx: a central regulator of vascular function

The endothelial glycocalyx is a specialized extracellular matrix that covers the apical side of vascular endothelial cells, projecting into the lumen of blood vessels. The composition of the glycocalyx has been studied in great detail, and it is known to be composed of a mixture of proteoglycans, glycosaminoglycans, and glycoproteins. Although this structure was once believed to be a passive physical barrier, it is now recognized as a multifunctional and dynamic structure that participates in many vascular processes, including but not limited to vascular permeability, inflammation, thrombosis, mechanotransduction, and cytokine signaling. Because of its participation in many physiological and pathophysiological states, comprehensive knowledge of the glycocalyx will aid future vascular biologists in their research. With that in mind, this review discusses the biochemical structure of the glycocalyx and its function in many vascular physiological processes. We also briefly review a more recent discovery in glycocalyx biology, the placental glycocalyx.

Liraglutide Improves Endothelial Function via the mTOR Signaling Pathway

BACKGROUND

Mammalian target of rapamycin (mTOR) is crucial for endothelial function. This study is aimed at assessing whether the glucagon-like peptide-1 (GLP-1) analogue liraglutide has a protective effect on endothelial function via the mTOR signaling pathway.

METHODS

Human umbilical vein endothelial cells (HUVECs) were administered liraglutide (100 nM) for 0, 10, 30, 60, 720, and 1440 minutes, respectively. Then, the expression and phosphorylation levels of mTOR, mTOR-Raptor complex (mTORC1), and mTOR-Rictor complex (mTORC2) were determined by Western blot and immunoprecipitation, while mTORC1 and mTORC2 expression was blocked by siRNA-Raptor and siRNA-Rictor, respectively. Akt phosphorylation was detected by Western blot. HUVECs were then incubated with liraglutide in the absence or presence of Akt inhibitor IV. Nitric oxide (NO) release was assessed by the nitrate reductase method. Phosphorylated endothelial nitric oxide synthase (eNOS), human telomerase reverse transcriptase (hTERT), and apoptosis-related effectors were assessed for protein levels by Western blot. Telomerase activity was evaluated by ELISA.

RESULTS

Sustained mTOR phosphorylation, mTORC2 formation, and mTORC2-dependent Akt phosphorylation were induced by liraglutide. In addition, eNOS phosphorylation, NO production, nuclear hTERT accumulation, and nuclear telomerase activity were enhanced by mTORC2-mediated Akt activation. Liraglutide also showed an antiapoptotic effect by upregulating antiapoptotic proteins and downregulating proapoptotic proteins in an mTORC2-Akt activation-dependent manner.

CONCLUSION

Liraglutide significantly improves endothelial function, at least partially via the mTORC2/Akt signaling pathway.

Gangrene, revascularization, and limb function improved with E-selectin/adeno-associated virus gene therapy

OBJECTIVE

Novel therapeutic angiogenic concepts for critical limb ischemia are still needed for limb salvage. E-selectin, a cell-adhesion molecule, is vital for recruitment of the stem/progenitor cells necessary for neovascularization in ischemic tissues. We hypothesized that priming ischemic limb tissue with E-selectin/adeno-associated virus (AAV) gene therapy, in a murine hindlimb ischemia and gangrene model, would increase therapeutic angiogenesis and improve gangrene.

METHODS

FVB/NJ mice were given intramuscular hindlimb injections of either E-selectin/AAV or LacZ/AAV and then underwent induction of gangrene via femoral artery ligation and concomitant systemic injections of the nitric oxide synthesis inhibitor L-NAME (L-NG-Nitro arginine methyl ester; 40 mg/kg). Gangrene was evaluated via the Faber hindlimb appearance score. The rate of ischemic limb reperfusion and ischemic tissue angiogenesis were evaluated using laser Doppler perfusion imaging and DiI perfusion with confocal laser scanning microscopy of the ischemic footpads, respectively. The treadmill exhaustion test was performed on postoperative day (POD) 8 to determine hindlimb functionality.

RESULTS

The E-selectin/AAV-treated mice (n = 10) had decreased Faber ischemia scores compared with those of the LacZ/AAV-treated mice (n = 7) at both PODs 7 and 14 (P < .05 and P < .01, respectively), improved laser Doppler perfusion imaging reperfusion indexes by POD 14 (P < .01), and greater gangrene footpad capillary density (P < .001). E-selectin/AAV-treated mice also had improved exercise tolerance (P < .05) and lower relative muscular atrophy (P < .01).

CONCLUSION

We surmised that E-selectin/AAV gene therapy would significantly promote hindlimb angiogenesis, reperfusion, and limb functionality in mice with hindlimb ischemia and gangrene. Our findings highlight the reported novel gene therapy approach to critical limb ischemia as a potential therapeutic option for future clinical studies.

Angiogenic biomaterials to promote therapeutic regeneration and investigate disease progression

The vasculature is a key component of the tissue microenvironment. Traditionally known for its role in providing nutrients and oxygen to surrounding cells, the vasculature is now also acknowledged to provide signaling cues that influence biological outcomes in regeneration and disease. These cues come from the cells that comprise vasculature, as well as the dynamic biophysical and biochemical properties of the surrounding extracellular matrix that accompany vascular development and remodeling. In this review, we illustrate the larger role of the vasculature in the context of regenerative biology and cancer progression. We describe cellular, biophysical, biochemical, and metabolic components of vascularized microenvironments. Moreover, we provide an overview of multidimensional angiogenic biomaterials that have been developed to promote therapeutic vascularization and regeneration, as well as to mimic elements of vascularized microenvironments as a means to uncover mechanisms by which vasculature influences cancer progression and therapy.

Exosomes from SIRT1-Overexpressing ADSCs Restore Cardiac Function by Improving Angiogenic Function of EPCs

Acute myocardial infarction (AMI) is one of the leading causes of mortality in cardiovascular diseases. The aim of this study was to investigate whether exosomes from Sirtuin 1 (SIRT1)-overexpressing adipose-derived stem cells (ADSCs) had a protective effect on AMI. The expression of C-X-C chemokine receptor type 7 (CXCR7) was significantly downregulated in peripheral blood endothelial progenitor cells (EPCs) from AMI patients (AMI-EPCs) compared with that in healthy donors, which coincided with impaired tube formation. The exosomes from SIRT1 overexpression in ADSCs (ADSCs-SIRT1-Exos) increased the expression of C-X-C motif chemokine 12 (CXCL12) and nuclear factor E2 related factor 2 (Nrf2) in AMI-EPCs, which promoted migration and tube formation of AMI-EPCs, and overexpression of CXCR7 helped AMI-EPCs to restore the function of cell migration and tube formation. Moreover, CXCR7 was downregulated in the myocardium of AMI mice, and knockout of CXCR7 exacerbated AMI-induced impairment of cardiovascular function. Injection of ADSCs-SIRT1-Exos increased the survival and promoted the recovery of myocardial function with reduced infarct size and post-AMI left ventricular remodeling, induced vasculogenesis, and decreased AMI-induced myocardial inflammation. These findings showed that ADSCs-SIRT1-Exos may recruit EPCs to the repair area and that this recruitment may be mediated by Nrf2/CXCL12/CXCR7 signaling.

Maternal, Fetal, and Placental Selectins in Women With Pre-eclampsia; Association With the Renin-Angiotensin-System

Selectins [endothelial (E), platelet (P), and leucocytes (L)] are a class of cell adhesion molecules, stimulated in response to inflammation. Pre-eclampsia is characterized by inflammation, and angiotensin II is pro-inflammatory. We hypothesized that circulating maternal and fetal concentrations and placental expression of selectins would be increased in women with pre-eclampsia and would be associated with the angiotensin receptors (AT1R and AT2R). Maternal and fetal blood and placental tissue was collected at delivery from White European normotensive controls (n = 17) and women with pre-eclampsia (n = 17). Soluble (s) E-, P- and L-selectin protein concentrations were measured by ELISA and placental protein expression was examined by immunohistochemistry. Maternal sE-selectin concentrations were increased in pre-eclampsia (P < 0.001); conversely fetal sE- and sP-selectin levels were lower in pre-eclampsia (P < 0.05 for both). Staining was mainly localized to the syncytiotrophoblast for all selectins. E-selectin expression was increased, while P-selectin was decreased in placental from pre-eclampsia (P < 0.05 for both); no differences were observed for L-selectin expression. Both E- and L-selectin were positively correlated (P < 0.008; P < 0.02) with AT2R placental expression, whilst P-selectin was negatively associated with AT1R (P < 0.005), all only in the pre-eclampsia group. This novel study reports maternal, fetal and placental expression of selectins in pre-eclampsia. The increased E-selectins reflect the endothelial dysfunction, characteristic of pre-eclampsia. In contrast, the reduced P-selectins and the positive association of placental AT2Rs with both E-and L-selectin in pre-eclampsia could be a protective mechanism to limit the endothelial dysfunction.

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.

CYP4A/20-HETE regulates ischemia-induced neovascularization via its actions on endothelial progenitor and preexisting endothelial cells

20-Hydroxyeicosatetraenoic acid (20-HETE) was recently identified as a novel contributor of ischemia-induced neovascularization based on the key observation that pharmacological interferences of CYP4A/20-HETE decrease ischemic neovascularization. The objective of the present study is to examine whether the underlying cellular mechanisms involve endothelial progenitor cells (EPCs) and preexisting endothelial cells (ECs). We found that ischemia leads to a time-dependent increase of cyp4a12 expression and 20-HETE production, which are endothelial in origin, using immunofluorescent microscopy, Western blot analysis, and LC-MS/MS. This is accompanied by increases in the tissue stromal cell-derived factor-1α (SDF-1α) expressions as well as SDF-1α plasma levels, EPC mobilization from bone marrow, and subsequent homing to ischemic tissues. Pharmacological interferences of CYP4A/20-HETE with a 20-HETE synthesis inhibitor, dibromo-dodecenyl-methylsulfimide (DDMS), or a 20-HETE antagonist, N-(20-hydroxyeicosa-6(Z), 15(Z)-dienoyl) glycine (6, 15-20-HEDGE), significantly attenuated these increases. Importantly, we also determined that 20-HETE plays a novel role in maintaining EPC functions and increasing the expression of Oct4, Sox2, and Nanog, which are indicative of increased progenitor cell stemness. Flow cytometric analysis revealed that pharmacological interferences of CYP4A/20-HETE decrease the EPC population in culture, whereas 20-HETE increases the cultured EPC population. Furthermore, ischemia also markedly increased the proliferation, oxidative stress, and ICAM-1 expression in the preexisting EC in the hindlimb gracilis muscles. We found that these increases were markedly negated by DDMS and 6, 15-20-HEDGE. Taken together, CYP4A/20-HETE regulates ischemia-induced compensatory neovascularization via its combined actions on promoting EPC and local preexisting EC responses that are associated with increased neovascularization. NEW & NOTEWORTHY CYP4A/20-hydroxyeicosatetraenoic acid (20-HETE) was recently discovered as a novel contributor of ischemia-induced neovascularization. However, the underlying molecular and cellular mechanisms are completely unknown. Here, we show that CYP4A/20-HETE regulates the ischemic neovascularization process via its combined actions on both endothelial progenitor cells (EPCs) and preexisting endothelial cells. Moreover, this is the first study, to the best of our knowledge, that associates CYP4A/20-HETE with EPC differentiation and stemness.

Exercise and Cardiovascular Progenitor Cells

Autologous stem/progenitor cell-based methods to restore blood flow and function to ischemic tissues are clinically appealing for the substantial proportion of the population with cardiovascular diseases. Early preclinical and case studies established the therapeutic potential of autologous cell therapies for neovascularization in ischemic tissues. However, trials over the past ∼15 years reveal the benefits of such therapies to be much smaller than originally estimated and a definitive clinical benefit is yet to be established. Recently, there has been an emphasis on improving the number and function of cells [herein generally referred to as circulating angiogenic cells (CACs)] used for autologous cell therapies. CACs include of several subsets of circulating cells, including endothelial progenitor cells, with proangiogenic potential that is largely exerted through paracrine functions. As exercise is known to improve CV outcomes such as angiogenesis and endothelial function, much attention is being given to exercise to improve the number and function of CACs. Accordingly, there is a growing body of evidence that acute, short-term, and chronic exercise have beneficial effects on the number and function of different subsets of CACs. In particular, recent studies show that aerobic exercise training can increase the number of CACs in circulation and enhance the function of isolated CACs as assessed in ex vivo assays. This review summarizes the roles of different subsets of CACs and the effects of acute and chronic exercise on CAC number and function, with a focus on the number and paracrine function of circulating CD34+ cells, CD31+ cells, and CD62E+ cells. © 2019 American Physiological Society. Compr Physiol 9:767-797, 2019.

Impact of Exercise on Inflammatory Mediators of Metabolic and Vascular Insulin Resistance in Type 2 Diabetes

The development of obesity is cornerstone in the etiology of metabolic and vascular insulin resistance and consequently exacerbates glycemic control. Exercise is an efficacious first-line therapy for type 2 diabetes that improves insulin action through, in part, reducing hormone mediated inflammation. Together, improving the coordination of skeletal muscle metabolism with vascular delivery of glucose will be required for optimizing type 2 diabetes and cardiovascular disease treatment.

TWEAK promotes endothelial progenitor cell vasculogenesis to alleviate acute myocardial infarction via the Fn14-NF-κB signaling pathway

Acute myocardial infarction (AMI) remains one of the leading causes of mortality worldwide; however, endothelial progenitor cell (EPC) transplantation has been proposed as a promising treatment strategy for EPC. High levels of tumor necrosis factor-related weak inducer of apoptosis (TWEAK) have been reported in AMI, although its effect on EPCs has not been reported. In the present study, immunofluorescence and flow cytometry were performed to assess the effect of TWEAK in isolated mouse EPCs. Echocardiography was used to evaluate the cardiac function of murine hearts following EPC treatment in the AMI model, while collagen synthesis within the heart tissue was assessed using Masson's trichrome staining. A tube formation assay and Transwell migration assay were performed to investigate the effects of TWEAK on vessel formation and EPC migration in vitro. Angiogenesis and arteriogenesis were assessed in vivo using immunohistochemistry and western blotting was performed to determine the effect of TWEAK-mediated nuclear factor (NF)-κB pathway activation in EPCs. The results revealed that TWEAK promotes EPC migration, tube formation and viability in vitro. Furthermore, TWEAK treatment resulted in improved cardiac function, decreased heart collagen and vasculogenesis in mice with AMI, which was mediated by the TWEAK- fibroblast growth factor-inducible 14 (Fn14)-NF-κB signaling pathway, as determined using Fn14 small interfering (si)RNA and Bay 11–7082 (an NF-κB inhibitor). In summary, the results of the present study suggest that activation of the TWEAK-Fn14-NF-κB signaling pathway exerts a beneficial effect on EPCs for the treatment of AMI.

Extracellular Vesicles: A Novel Target for Exercise-Mediated Reductions in Type 2 Diabetes and Cardiovascular Disease Risk

Regular exercise is important for reducing type 2 diabetes (T2D) and/or cardiovascular disease (CVD) risk. However, only about 40-50% of this CVD risk reduction is accounted for by adiposity, hyperglycemia, hypertension, and dyslipidemia. Herein, we present the novel hypothesis that extracellular vesicles (EVs) are candidate biomarkers that may relate to impaired endothelial function and insulin resistance independent of obesity risk factors. EVs are small membrane-bound particles that are generated by cells following stimulation, stress, or activation. They carry markers of their parent cell and are thought to be potent bioactivators and communicators. We discuss the underlying physiology of specific cell type EVs, as well as examine how acute and chronic exercise interventions impact EV count and phenotype. We also propose that current gaps in the field are in part related to use of different detection techniques and the lack of standardized measurements of EV affecting the pre- and postanalytical phase. Ultimately, improving the understanding of how EVs impact cardiometabolic health and their function will lead to improved approaches for enhancing diagnostic options as well as designing exercise interventions that treat and/or prevent T2D and CVD.

Oral Ibuprofen Interferes with Cellular Healing Responses in a Murine Model of Achilles Tendinopathy

Background:

The attempted healing of tendon after acute injury (overloading, partial tear or complete rupture) proceeds via the normal wound healing cascade involving hemostasis, inflammation, matrix synthesis and matrix remodeling. Depending on the degree of trauma and the nature of the post-injury milieu, a variable degree of healing and recovery of function occurs. Post-injury analgesia is often achieved with NSAIDs such as Ibuprofen, however there is increasing evidence that NSAID usage may interfere with the healing process. This study aimed to investigate the cellular mechanism by which IBU therapy might lead to a worsening of tendon pathology.

Methods:

We have examined the effect of oral Ibuprofen, on Achilles tendon healing in a TGFb1-induced murine tendinopathy model. Dosing was started 3 days after initial injury (acute cellular response phase) and continued for 22 days or started at 9 days after injury (transition to matrix regeneration phase) and given for 16 days. Cellular changes in tendon and surrounding peritenon were assessed using Hematoxylin/Eosin, chondroid accumulation with Safranin O and anti-aggrecan immunohistochemistry, and neo-vessel formation with GSI Lectin histochemistry. Markers of inflammation included histochemical localization of hyaluronan, immunohistochemistry of heavy chain 1 and TNFα-stimulated glycoprotein-6 (TSG6). Cell responses were further examined by RT-qPCR of 84 NFκB target genes and 84 wound healing genes. Biomechanical properties of tendons were evaluated by tensile testing.

Results:

At a clinically-relevant dosage, Ibuprofen prevented the process of remodeling/removal of the inflammatory matrix components, hyaluronan, HC1 and TSG6. Furthermore, the aberrant matrix remodeling was accompanied by activation at day 28 of genes (Col1a2, Col5a3, Plat, Ccl12, Itga4, Stat3, Vegfa, Mif, Col4a1, Rhoa, Relb, F8, Cxcl9, Lta, Ltb, Ccl12, Cdkn1a, Ccl22, Sele, Cd80), which were not activated at any time without the drug, and so appear most likely to be involved in the pathology. Of these, Vegfa, Col4a1, F8, Cxcl9 and Sele, have been shown to play a role in vascular remodeling, consistent with the appearance at 25 days of vasculogenic cell groups in the peritenon and fat pad stroma surrounding the Achilles of the drug-dosed mice. Tensile stiffness (p = 0.004) and elastic modulus (p = 0.012) were both decreased (relative to age-matched uninjured and non-dosed mice) in mice dosed with Ibuprofen from day 3 to day 25, whether injured or not.

Conclusion:

We conclude that the use of Ibuprofen for pain relief during inflammatory phases of tendinopathy, might interfere with the normal processes of extracellular matrix remodeling and cellular control of expression of inflammatory and wound healing genes. It is proposed that the known COX2-mediated anti-inflammatory effect of ibuprofen has detrimental effects on the turnover of a pro-inflammatory HA matrix produced in response to soft-tissue injury, thus preventing the switch to cellular responses associated with functional matrix remodeling and eventual healing.

Important signals regulating coronary artery angiogenesis

Angiogenesis is a complex process of budding, the formation of new blood vessels from pre-existing microvessels, via migration, proliferation and survival. Vascular angiogenesis factors include different classes of molecules that have a fundamental role in blood vessel formation. Numerous inducers of angiogenesis, such as the members of the vascular endothelial growth factor (VEGF) family, basic fibroblast growth factor (bFGF), angiopoietin (Ang), hepatocyte growth factor (HGF), and hypoxia inducible factor-1 (HIF-1), have an important role in angiogenesis. However, VEGF, platelet-derived growth factor (PDGF), and transforming growth factor β (TGF-β) expression appear to be important in intraplaque angiogenesis. Interaction and combined effects between growth factors is essential in endothelial cell migration, proliferation, differentiation, and endothelial cell-cell communication that ultimately lead to the microvessel formation. Since VEGF has a key role during angiogenesis; it may be considered as a good therapeutic target in the clinic. The essential function of several angiogenic factors involved in coronary angiogenesis and intraplaque angiogenesis in atherosclerosis are carefully considered along with the use of angiogenic factors in clinical practice.

Assessment of Molecular Acoustic Angiography for Combined Microvascular and Molecular Imaging in Preclinical Tumor Models

PURPOSE

The purposes of the present study is to evaluate a new ultrasound molecular imaging approach in its ability to image a preclinical tumor model and to investigate the capacity to visualize and quantify co-registered microvascular and molecular imaging volumes.

PROCEDURES

Molecular imaging using the new technique was compared with a conventional ultrasound molecular imaging technique (multi-pulse imaging) by varying the injected microbubble dose and scanning each animal using both techniques. Each of the 14 animals was randomly assigned one of three doses; bolus dose was varied, and the animals were imaged for three consecutive days so that each animal received every dose. A microvascular scan was also acquired for each animal by administering an infusion of nontargeted microbubbles. These scans were paired with co-registered molecular images (VEGFR2-targeted microbubbles), the vessels were segmented, and the spatial relationships between vessels and VEGFR2 targeting locations were analyzed. In five animals, an additional scan was performed in which the animal received a bolus of microbubbles targeted to E- and P-selectins. Vessel tortuosity as a function of distance from VEGF and selectin targeting was analyzed in these animals.

RESULTS

Although resulting differences in image intensity due to varying microbubble dose were not significant between the two lowest doses, superharmonic imaging had significantly higher contrast-to-tissue ratio (CTR) than multi-pulse imaging (mean across all doses 13.98 dB for molecular acoustic angiography vs. 0.53 dB for multi-pulse imaging; p = 4.9 × 10^-10). Analysis of registered microvascular and molecular imaging volumes indicated that vessel tortuosity decreases with increasing distance from both VEGFR2- and selectin-targeting sites.

CONCLUSIONS

Molecular acoustic angiography (superharmonic molecular imaging) exhibited a significant increase in CTR at all doses tested due to superior rejection of tissue artifact signals. Due to the high resolution of acoustic angiography molecular imaging, it is possible to analyze spatial relationships in aligned microvascular and molecular superharmonic imaging volumes. Future studies are required to separate the effects of biomarker expression and blood flow kinetics in comparing local tortuosity differences between different endothelial markers such as VEGFR2, E-selectin, and P-selectin.

Experimental intermittent ischemia augments exercise-induced inflammatory cytokine production

Acute exercise-induced inflammation is implicated in mediating the beneficial adaptations to regular exercise. Evidence suggests that reduced oxygen and/or blood flow to contracting muscle alters cytokine appearance. However, the acute inflammatory responses to hypoxic/ischemic exercise have been documented with inconsistent results and may not accurately reflect the ischemia produced during exercise in patients with ischemic cardiovascular diseases. Therefore, we determined the extent to which local inflammation is involved in the response to ischemic exercise. Fourteen healthy males performed unilateral isometric forearm contractions for 30 min with and without experimental ischemia. Blood was drawn at baseline, 5 and 10 min into exercise, at the end of exercise, and 30, 60, and 120 min after exercise. Oxygen saturation levels, as measured by near-infrared spectroscopy, were reduced by 10% and 41% during nonischemic and ischemic exercise, respectively. Nonischemic exercise did not affect cytokine values. Ischemia enhanced concentrations of basic fibroblast growth factor, interleukin (IL)-6, IL-10, tumor necrosis factor-alpha, and vascular endothelial growth factor during exercise, but IL-8 was not influenced by ischemic exercise. In conclusion, the present study demonstrates that ischemic, small-muscle endurance exercise elicits local inflammatory cytokine production compared with nonischemic exercise.

NEW & NOTEWORTHY We demonstrate that ischemic, small-muscle endurance exercise elicits local inflammatory cytokine production compared with nonischemic exercise. The present study advances our knowledge of the inflammatory response to exercise in a partial ischemic state, which may be relevant for understanding the therapeutic effects of exercise training for people with ischemic cardiovascular disease-associated comorbidities.

Vascular precursor cells in tissue injury repair

Vascular precursor cells include stem cells and progenitor cells giving rise to all mature cell types in the wall of blood vessels. When tissue injury occurs, local hypoxia and inflammation result in the generation of vasculogenic mediators which orchestrate migration of vascular precursor cells from their niche environment to the site of tissue injury. The intricate crosstalk among signaling pathways coordinates vascular precursor cell proliferation and differentiation during neovascularization. Establishment of normal blood perfusion plays an essential role in the effective repair of the injured tissue. In recent years, studies on molecular mechanisms underlying the regulation of vascular precursor cell function have achieved substantial progress, which promotes exploration of vascular precursor cell-based approaches to treat chronic wounds and ischemic diseases in vital organ systems. Verification of safety and establishment of specific guidelines for the clinical application of vascular precursor cell-based therapy remain major challenges in the field.

Exercise-induced upregulation of endothelial adhesion molecules in human skeletal muscle and number of circulating cells with remodeling properties

Multipotent cells have received great interest because of their potential capacity to repair and remodel peripheral tissues. We examined the effect of an acute exercise bout on the number of circulating cells with known remodeling properties and the level of factors in plasma and skeletal muscle tissue with potential to recruit these cells. Twenty healthy male subjects performed a 60-min cycling exercise. Blood samples for flow cytometry were drawn from 10 subjects (group 1) before and up to 2 h after exercise, and absolute cell counts of the classical (CD14⁺⁺CD16^-), intermediate (CD14⁺⁺CD16⁺), and nonclassical (CD14⁺CD16⁺⁺) monocyte (MO) subpopulations and of CD45^dimCD34⁺VEGFR2⁺ endothelial progenitor cells (EPCs) were measured by bead-based determination. Plasma samples and vastus lateralis muscle biopsies were obtained from the other 10 subjects (group 2). In group 1, all MO subsets were increased directly after exercise, with CD14⁺CD16⁺⁺ MOs showing the greatest fold increase. After 2 h, only CD14⁺⁺CD16^- MOs were increased compared with resting levels. The number of EPCs showed a trend toward increasing with exercise (P = 0.08). In group 2, the mRNA levels of the endothelial adhesion molecules ICAM-1, VCAM-1, and E-selectin increased in the skeletal muscle tissue. VEGF-A increased in exercised skeletal muscle and stimulated the expression of VCAM-1 and E-selectin in human umbilical vein endothelial cells. In conclusion, exercise increases MO subsets with different temporal patterns and enhances the capacity of skeletal muscle tissue to recruit circulating cells as shown by increased expression of endothelial adhesion molecules.NEW & NOTEWORTHY In the present study we showed for the first time that the adhesion molecules ICAM-1, VCAM-1, and E-selectin, known to be able to recruit circulating cells to the peripheral tissue, increased in exercised human skeletal muscle concurrently with increased circulating levels of cells shown to have importance for skeletal muscle remodeling. These findings support the concept of cell recruitment from the circulation playing a role in skeletal muscle adaptation to exercise.

Pivotal Cytoprotective Mediators and Promising Therapeutic Strategies for Endothelial Progenitor Cell-Based Cardiovascular Regeneration

Cardiovascular diseases (CVDs), including atherosclerosis, stroke, and myocardial infarction, is a major cause of death worldwide. In aspects of cell therapy against CVD, it is generally accepted that endothelial progenitor cells (EPCs) are potent neovascular modulators in ischemic tissues. In response to ischemic injury signals, EPCs located in a bone marrow niche migrate to injury sites and form new vessels by secreting various vasculogenic factors including VEGF, SDF-1, and FGF, as well as by directly differentiating into endothelial cells. Nonetheless, in ischemic tissues, most of engrafted EPCs do not survive under harsh ischemic conditions and nutrient depletion. Therefore, an understanding of diverse EPC-related cytoprotective mediators underlying EPC homeostasis in ischemic tissues may help to overcome current obstacles for EPC-mediated cell therapy for CVDs. Additionally, to enhance EPC's functional capacity at ischemic sites, multiple strategies for cell survival should be considered, that is, preconditioning of EPCs with function-targeting drugs including natural compounds and hormones, virus mediated genetic modification, combined therapy with other stem/progenitor cells, and conglomeration with biomaterials. In this review, we discuss multiple cytoprotective mediators of EPC-based cardiovascular repair and propose promising therapeutic strategies for the treatment of CVDs.

Mitochondria-specific antioxidant supplementation does not influence endurance exercise training-induced adaptations in circulating angiogenic cells, skeletal muscle oxidative capacity or maximal oxygen uptake

KEY POINTS

Reducing excessive oxidative stress, through chronic exercise or antioxidants, can decrease the negative effects induced by excessive amounts of oxidative stress. Transient increases in oxidative stress produced during acute exercise facilitate beneficial vascular training adaptations, but the effects of non-specific antioxidants on exercise training-induced vascular adaptations remain elusive. Circulating angiogenic cells (CACs) are an exercise-inducible subset of white blood cells that maintain vascular integrity. We investigated whether mitochondria-specific antioxidant (MitoQ) supplementation would affect the response to 3 weeks of endurance exercise training in CACs, muscle mitochondrial capacity and maximal oxygen uptake in young healthy men. We show that endurance exercise training increases multiple CAC types, an adaptation that is not altered by MitoQ supplementation. Additionally, MitoQ does not affect skeletal muscle or whole-body aerobic adaptations to exercise training. These results indicate that MitoQ supplementation neither enhances nor attenuates endurance training adaptations in young healthy men.

ABSTRACT

Antioxidants have been shown to improve endothelial function and cardiovascular outcomes. However, the effects of antioxidants on exercise training-induced vascular adaptations remain elusive. General acting antioxidants combined with exercise have not impacted circulating angiogenic cells (CACs). We investigated whether mitochondria-specific antioxidant (MitoQ) supplementation would affect the response to 3 weeks of endurance exercise training on CD3+ , CD3+ /CD31+ , CD14+ /CD31+ , CD31+ , CD34+ /VEGFR2+ and CD62E+ peripheral blood mononuclear cells (PBMCs), muscle mitochondrial capacity, and maximal oxygen uptake (VO2 max ) in healthy men aged 22.1 ± 0.7 years, with a body mass index of 26.9 ± 0.9 kg m-2 , and 24.8 ± 1.3% body fat. Analysis of main effects revealed that training induced 33, 105 and 285% increases in CD14+ /CD31+ , CD62E+ and CD34+ /VEGFR2+ CACs, respectively, and reduced CD3+ /CD31- PBMCs by 14%. There was no effect of MitoQ on CAC levels. Also independent of MitoQ supplementation, exercise training significantly increased quadriceps muscle mitochondrial capacity by 24% and VO2 max by roughly 7%. In conclusion, endurance exercise training induced increases in multiple CAC types, and this adaptation is not modified by MitoQ supplementation. Furthermore, we demonstrate that a mitochondrial-targeted antioxidant does not influence skeletal muscle or whole-body aerobic adaptations to exercise training.

SDF-1α-induced dual pairs of E-selectin/ligand mediate endothelial progenitor cell homing to critical ischemia

Homing of endothelial progenitor cells (EPC) to the ischemic tissues is a key event in neovascularization and tissue regeneration. In response to ischemic insult, injured tissues secrete several chemo-cytokines, including stromal cell-derived factor-1α (SDF-1α), which triggers mobilization and homing of bone marrow-derived EPC (BMD-EPC). We previously reported that SDF-1α-induced EPC homing is mediated by a panel of adhesion molecules highly or selectively expressed on the activated endothelium in ischemic tissues, including E-selectin. Elevated E-selectin on wound vasculature serve as docking sites for circulating EPC, which express counterpart E-selectin ligands. Here, we show that SDF-1α presented in wound tissue and released into circulation can act both locally and remotely to induce ischemic tissue endothelium and BMD-EPC to express both E-selectin and its ligands. By performing BM transplantation using E-selectin^−/− and E-selectin^+/+ mice as the donors and recipients respectively, we demonstrate that upregulated dual E-selectin/ligand pairs reciprocally expressed on ischemic tissue endothelium and BMD-EPC act as double-locks to secure targeted EPC- endothelium interactions by which to facilitate EPC homing and promote neovascularization and tissue repair. These findings describe a novel mechanism for BMD-EPC homing and indicate that dual E-selectin/ligand pairs may be effective targets/tools for therapeutic neovascularization and targeted cell delivery.

Caveolin-1, Ring finger protein 213, and endothelial function in Moyamoya disease

BACKGROUND

Moyamoya disease is a unique cerebrovascular occlusive disease of unknown etiology. Ring finger protein 213 (RNF213) was identified as a susceptibility gene for Moyamoya disease in East Asian countries. However, the pathogenesis of Moyamoya disease remains unclear.

METHODS

We prospectively analyzed clinical data for 139 patients with Moyamoya disease (108 bilateral Moyamoya disease, 31 unilateral Moyamoya disease), 61 patients with intracranial atherosclerotic stroke, and 68 healthy subjects. We compared the genetic (RNF213 variant) and protein biomarkers for caveolae (caveolin-1), angiogenesis (vascular endothelial growth factor (VEGF) and receptor (VEGFR2), and antagonizing cytokine (endostatin)) and endothelial dysfunction (asymmetric dimethylarginine (ADMA), and nitric oxide and its metabolites (nitrite and nitrate)) between patients with Moyamoya disease and intracranial atherosclerotic stroke. We then performed path analysis to evaluate whether a certain protein biomarker mediates the association between genes and Moyamoya disease.

RESULTS

Caveolin-1 level was decreased in patients with Moyamoya disease and markedly decreased in RNF213 variant carriers. Circulating factors such as VEGF and VEGFR2 did not differ among the groups. Markers for endothelial dysfunction were significantly higher in patients with intracranial atherosclerotic stroke but normal in those with Moyamoya disease. Path analysis showed that the presence of the RNF213 variant was associated with caveolin-1 levels that could lead to Moyamoya disease. The level of combined marker of Moyamoya disease (caveolin-1) and intracranial atherosclerotic stroke (ADMA, an endothelial dysfunction marker) predicted Moyamoya disease with good sensitivity and specificity.

CONCLUSION

Our results suggest that Moyamoya disease is a caveolae disorder but is not related to endothelial dysfunction or dysregulation of circulating cytokines.

Blast Wave Exposure to the Extremities Causes Endothelial Activation and Damage

Extremity injury is a significant burden to those injured in explosive incidents and local ischaemia can result in poor functionality in salvaged limbs. This study examined whether blast injury to a limb resulted in a change in endothelial phenotype leading to changes to the surrounding tissue.

The hind limbs of terminally anaesthetized rabbits were subjected to one of four blast exposures (high, medium, low, or no blast). Blood samples were analyzed for circulating endothelial cells pre-injury and at 1, 6, and 11 h postinjury as well as analysis for endothelial activation pre-injury and at 1, 6, and 12 h postinjury. Post-mortem tissue (12 h post-injury) was analysed for both protein and mRNA expression and also for histopathology. The high blast group had significantly elevated levels of circulating endothelial cells 6 h postinjury. This group also had significantly elevated tissue mRNA expression of IL-6, E-selectin, TNF-α, HIF-1, thrombomodulin, and PDGF. There was a significant correlation between blast dose and the degree of tissue pathology (hemorrhage, neutrophil infiltrate, and oedema) with the worst scores in the high blast group. This study has demonstrated that blast injury can activate the endothelium and in some cases cause damage that in turn leads to pathological changes in the surrounding tissue. For the casualty injured by an explosion the damaging effects of hemorrhage and shock could be exacerbated by blast injury and vice versa so that even low levels of blast become damaging, all of which could affect tissue functionality and long-term outcomes.

Directing and Potentiating Stem Cell-Mediated Angiogenesis and Tissue Repair by Cell Surface E-Selectin Coating

Stem cell therapy has emerged as a promising approach for treatment of a number of diseases, including delayed and non-healing wounds. However, targeted systemic delivery of therapeutic cells to the dysfunctional tissues remains one formidable challenge. Herein, we present a targeted nanocarrier-mediated cell delivery method by coating the surface of the cell to be delivered with dendrimer nanocarriers modified with adhesion molecules. Infused nanocarrier-coated cells reach to destination via recognition and association with the counterpart adhesion molecules highly or selectively expressed on the activated endothelium in diseased tissues. Once anchored on the activated endothelium, nanocarriers-coated transporting cells undergo transendothelial migration, extravasation and homing to the targeted tissues to execute their therapeutic role. We now demonstrate feasibility, efficacy and safety of our targeted nanocarrier for delivery of bone marrow cells (BMC) to cutaneous wound tissues and grafted corneas and its advantages over conventional BMC transplantation in mouse models for wound healing and neovascularization. This versatile platform is suited for targeted systemic delivery of virtually any type of therapeutic cell.

NOTCH4 signaling controls EFNB2-induced endothelial progenitor cell dysfunction in preeclampsia

Preeclampsia is a serious complication of pregnancy and is closely related to endothelial dysfunction, which can be repaired by endothelial progenitor cells (EPCs). The DLL4/NOTCH-EFNB2 (ephrinB2) cascade may be involved in the pathogenesis of preeclampsia by inhibiting the biological activity of EPCs. In addition, both NOTCH1 and NOTCH4, which are specific receptors for DLL4/NOTCH, play critical roles in the various steps of angiogenesis. However, it has not been determined which receptor (NOTCH1, NOTCH4, or both) is specific for the DLL4/NOTCH-EFNB2 cascade. Accordingly, we performed a series of investigations to evaluate it. EFNB2 expression was examined when NOTCH4 or NOTCH1 was downregulated, with or without DLL4 treatment. Then, the effects of NOTCH4 on EPC function were detected. Additionally, we analyzed NOTCH4 and EFNB2 expression in the EPCs from preeclampsia and normal pregnancies. Results showed that NOTCH4 downregulation led to decreased expression of EFNB2, which maintained the same level in the presence of DLL4/NOTCH activation. By contrast, NOTCH1 silencing resulted in a moderate increase in EFNB2 expression, which further increased in the presence of DLL4/NOTCH activation. The downregulation of NOTCH4 resulted in an increase of EPC biological activity, which was similar to EFNB2 silencing. NOTCH4 expression, consistent with the EFNB2 level, increased notably in preeclampsia EPCs compared with the controls. These findings suggest that NOTCH4, not NOTCH1, is the specific receptor for the DLL4/NOTCH-EFNB2 cascade. Blockade of this cascade may enhance the angiogenic property of EPCs, and act as a potential target to promote angiogenesis in patients with preeclampsia.

Low-Molecular-Weight Fucoidan Induces Endothelial Cell Migration via the PI3K/AKT Pathway and Modulates the Transcription of Genes Involved in Angiogenesis

Low-molecular-weight fucoidan (LMWF) is a sulfated polysaccharide extracted from brown seaweed that presents antithrombotic and pro-angiogenic properties. However, its mechanism of action is not well-characterized. Here, we studied the effects of LMWF on cell signaling and whole genome expression in human umbilical vein endothelial cells and endothelial colony forming cells. We observed that LMWF and vascular endothelial growth factor had synergistic effects on cell signaling, and more interestingly that LMWF by itself, in the absence of other growth factors, was able to trigger the activation of the PI3K/AKT pathway, which plays a crucial role in angiogenesis and vasculogenesis. We also observed that the effects of LMWF on cell migration were PI3K/AKT-dependent and that LMWF modulated the expression of genes involved at different levels of the neovessel formation process, such as cell migration and cytoskeleton organization, cell mobilization and homing. This provides a better understanding of LMWF’s mechanism of action and confirms that it could be an interesting therapeutic approach for vascular repair.

TLR4 stimulation by LPS enhances angiogenesis in a co-culture system consisting of primary human osteoblasts and outgrowth endothelial cells

The development of new approaches leading to fast and successful vascularization of tissue-engineered constructs is one of the most intensively studied subjects in tissue engineering and regenerative medicine. Recently, TLR4 activation and LPS stimulation of endothelial cells have been reported to promote angiogenesis in a variety of settings. In this study, we demonstrate that TLR4 activation by Ultrapure LPS Escherichia coli 0111:B4 (LPS-EB) significantly enhances microvessel formation in a co-culture system consisting of outgrowth endothelial cells (OECs) and primary human osteoblasts (pOBs). The precise modes of TLR4 action on the process of angiogenesis have also been investigated in this study. Using quantitative fluorescence microscopy in monocultures of OECs and pOBs, it was found that TLR4 activation through LPS-EB upregulates the expression level of TLR4/MYD88 and enhances both angiogenesis and osteogenesis. Furthermore, ELISA and qRT-PCR have shown that the level of two adhesion molecules (ICAM-1 and E-selectin), two cytokines (IL-6 and IL-8) and two growth factors (VEGF and PDGF-BB) related to angiogenesis increase significantly after LPS-EB treatment. This increased understanding of the role of TLR4 in angiogenesis could be of value in various settings related to tissue repair and tissue engineering. Moreover, since LPS and TLR4 agonists improve angiogenesis and osteogenesis, TLR4 agonists (endogenous or synthetic) could be used for angiogenesis intervention in vivo and therefore could be tested for their potential clinical applications in promoting angiogenesis in bone tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.

Strategies to Enhance the Efficiency of Endothelial Progenitor Cell Therapy by Ephrin B2 Pretreatment and Coadministration with Smooth Muscle Progenitor Cells on Vascular Function during the Wound-Healing Process in Irradiated or Nonirradiated Condition

Endothelial progenitor cell (EPC) transplantation has beneficial effects for therapeutic neovascularization. We therefore assessed the effect of a therapeutic strategy based on EPC administation in the healing of radiation-induced damage. To improve cell therapy for clinical use, we used pretreatment with ephrin B2-Fc (Eph-B2-Fc) and/or coadministration with smooth muscle progenitor cells. At day 3, EPCs promoted dermal wound healing in both nonirradiated and irradiated mice by 1.2- and 1.15-fold, respectively, compared with animals injected with phosphate-buffered saline. In addition, EPCs also improved skin-blood perfusion and capillary density in both irradiated and nonirradiated mice compared with PBS-injected animals. We also demonstrated that activation with Eph-B2-Fc increased wound closure by 1.6-fold compared with unstimulated EPCs in nonirradiated mice. Interestingly, the beneficial effect of Eph-B2-Fc was abolished in irradiated animals. In addition, we found that Eph-B2-Fc stimulation did not improve EPC-induced vascular permeability or adhesiveness compared to unstimulated EPCs. We hypothesized that this effect was due to high oxidative stress during irradiation, leading to inhibition of EPCs' beneficial effect on vascular function. In this line, we demonstated that, in irradiated conditions, N-acetyl-l-cysteine treatment restored the beneficial effect of EPC stimulation with Eph-B2-Fc in the wound healing process. In conclusion, stimulation by Eph-B2-Fc improved the beneficial effect of EPCs in physiological conditions and irradiated conditions only in association with antioxidant treatment. Additionally, cotherapy was beneficial in pathological conditions.

Thrombin receptor PAR-1 activation on endothelial progenitor cells enhances chemotaxis-associated genes expression and leukocyte recruitment by a COX-2-dependent mechanism

BACKGROUND

Endothelial colony forming cells (ECFC) represent a subpopulation of endothelial progenitor cells involved in endothelial repair. The activation of procoagulant mechanisms associated with the vascular wall's inflammatory responses to injury plays a crucial role in the induction and progression of atherosclerosis. However, little is known about ECFC proinflammatory potential.

AIMS

To explore the role of the thrombin receptor PAR-1 proinflammatory effects on ECFC chemotaxis/recruitment capacity.

METHODS AND RESULTS

The expression of 30 genes known to be associated with inflammation and chemotaxis was quantified in ECFC by real-time qPCR. PAR-1 activation with the SFLLRN peptide (PAR-1-ap) resulted in a significant increase in nine chemotaxis-associated genes expression, including CCL2 and CCL3 whose receptors are present on ECFC. Furthermore, COX-2 expression was found to be dramatically up-regulated consequently to PAR-1 activation. COX-2 silencing with the specific COX-2-siRNA also triggered down-regulation of the nine target genes. Conditioned media (c.m.) from control-siRNA- and COX-2-siRNA-transfected ECFC, stimulated or not with PAR-1-ap, were produced and tested on ECFC capacity to recruit leukocytes in vitro as well in the muscle of ischemic hindlimb in a preclinical model. The capacity of the c.m. from ECFC stimulated with PAR-1-ap to recruit leukocytes was abrogated when COX-2 gene expression was silenced in vitro (in terms of U937 cells migration and adhesion to endothelial cells) as well as in vivo. Finally, the postnatal vasculogenic stem cell derived from infantile hemangioma tumor (HemSC) incubated with PAR-1-ap increased leukocyte recruitment in Matrigel(®) implant.

CONCLUSIONS

PAR-1 activation in ECFC increases chemotactic gene expression and leukocyte recruitment at ischemic sites through a COX-2-dependent mechanism.

Endothelial progenitor cells in ischemic stroke: an exploration from hypothesis to therapy

As the population ages and lifestyles change in concordance, the number of patients suffering from ischemic stroke and its associated disabilities is increasing. Studies on determining the relationship between endothelial progenitor cells (EPCs) and ischemic stroke have become a new hot spot and have reported that EPCs may protect the brain against ischemic injury, promote neurovascular repair, and improve long-term neurobehavioral outcomes. More importantly, they introduce a new perspective for prognosis assessment and therapy of ischemic stroke. However, EPCs’ origin, function, influence factors, injury repair mechanisms, and cell-based therapy strategies remain controversial. Particularly, research conducted to date has less clinical studies than pre-clinical experiments on animals. In this review, we summarized and analyzed the current understanding of basic characteristics, influence factors, functions, therapeutic strategies, and disadvantages of EPCs as well as the regulation of inflammatory factors involved in the function and survival of EPCs after ischemic stroke. Identifying potential therapeutic effects of EPCs in ischemic stroke will be a challenging but an incredibly important breakthrough in neurology, which may bring promise for patients with ischemic stroke.