Differentiation Of Endothelial Progenitor Cells Research Articles

Effect of Human Umbilical Vein Endothelial Cell Culture Media (HUVEC-CM) on of Endothelial Progenitor Cells Differentiation and Construction of Enzyme-Sensitive Hydrogel Culture System

Effect of Human Umbilical Vein Endothelial Cell Culture Media (HUVEC-CM) on of Endothelial Progenitor Cells Differentiation and Construction of Enzyme-Sensitive Hydrogel Culture System

Tissue Engineered Bio‐Blood‐Vessels Constructed Using a Tissue‐Specific Bioink and 3D Coaxial Cell Printing Technique: A Novel Therapy for Ischemic Disease

Endothelial progenitor cells (EPCs) are a promising cell source for the treatment of several ischemic diseases for their potentials in neovascularization. However, the application of EPCs in cell‐based therapy has shown low therapeutic efficacy due to hostile tissue conditions after ischemia. In this study, a bio‐blood‐vessel (BBV) is developed, which is produced using a novel hybrid bioink (a mixture of vascular‐tissue‐derived decellularized extracellular matrix (VdECM) and alginate) and a versatile 3D coaxial cell printing method for delivering EPC and proangiogenic drugs (atorvastatin) to the ischemic injury sites. The hybrid bioink not only provides a favorable environment to promote the proliferation, differentiation, and neovascularization of EPCs but also enables a direct fabrication of tubular BBV. By controlling the printing parameters, the printing method allows to construct BBVs in desired dimensions, carrying both EPCs and atorvastatin‐loaded poly(lactic‐co‐glycolic) acid microspheres. The therapeutic efficacy of cell/drug‐laden BBVs is evaluated in an ischemia model at nude mouse hind limb, which exhibits enhanced survival and differentiation of EPCs, increased rate of neovascularization, and remarkable salvage of ischemic limbs. These outcomes suggest that the 3D‐printed ECM‐mediated cell/drug implantation can be a new therapeutic approach for the treatment of various ischemic diseases.

Substrate stiffness regulates arterial-venous differentiation of endothelial progenitor cells via the Ras/Mek pathway

Cells sense and respond to the biophysical properties of their surrounding environment by interacting with the extracellular matrix (ECM). Therefore, the optimization of these cell–matrix interactions is critical in tissue engineering. The vascular system is adapted to specific functions in diverse tissues and organs. Appropriate arterial-venous differentiation is vital for the establishment of functional vasculature in angiogenesis. Here, we have developed a polydimethylsiloxane (PDMS)-based substrate capable of simulating the physiologically relevant stiffness of both venous (7kPa) and arterial (128kPa) tissues. This substrate was utilized to investigate the effects of changes in substrate stiffness on the differentiation of endothelial progenitor cells (EPCs). As EPCs derived from mouse bone marrow were cultured on substrates of increasing stiffness, the mRNA and protein levels of the specific arterial endothelial cell marker ephrinB2 were found to increase, while the expression of the venous marker EphB4 decreased. Further experiments were performed to identify the mechanotransduction pathway involved in this process. The results indicated that substrate stiffness regulates the arterial and venous differentiation of EPCs via the Ras/Mek pathway. This work shows that modification of substrate stiffness may represent a method for regulating arterial-venous differentiation for the fulfilment of diverse functions of the vasculature.

Abstract 793: Human endothelial progenitor cells: A new target for anti-vascular therapy

Abstract Breast cancer affects one in eight women in the USA. Early diagnosis and newer treatment modalities have rendered breast cancer manageable. However, triple negative breast cancer is still difficult to treat and warrantes a search for newer targets. One strategy that has emerged in cancer research involves targeting of tumor associated blood vessels which provide growing tumors with oxygenated blood and growth factors necessary for maintenance and metastasis. Antiangiogenic drug therapy is transient and has not been able to gain mainstream therapeutic modality. We discovered that endothelial progenitor cells (EPCs) are mobilized from the bone marrow to the tumor site and contribute to the development of breast tumor vessel formation in an estrogen dependent manner. Therefore, characterization of tumor associated endothelial progenitor cells in breast cancer may provide a more specific antivascular therapy. Using the highly proliferative human umbilical cord blood derived EPCs, having the phenotype (CD133+, CD34+, VEGFR-2+), the effect of growth factor and chemokine rich EPCs conditioned medium (CM) was assessed in luminal (MCF-7), and post-EMT (MDA-MB-231) breast carcinoma cell lines. We observed an initial halt in cellular proliferation in MCF-7 followed by a significant increase in proliferation after forty eight hours of treatment. On the other hand, MDA-MB-231 showed decreased proliferation even after forty eight hours of treatment. Treating the EPCs with breast cancer conditioned medium resulted in morphological and cellular growth changes in the EPCs. MDA-MB-231 CM resulted in an increase of the EPCs proliferation and differentiation by increasing the number of spindle shaped attaching cells, and MCF-7 CM resulted only in an increase in the differentiation rate by increasing the number of cell clusters. This increase in EPCs proliferation and differentiation associated with MDA-MB-231 CM treatment might explain the invasiveness of this breast cancer cells through the increase in the tumor associated neovascularization. The analysis of the paracrine interaction between breast cancer cells and EPCs along with the associated cellular changes will facilitate identification of the interactive mediators and subsequent development of effective antivascular therapy. Citation Format: Ghada Ben Rahoma, Neha Tuli, Rachana Maniyar, Sanjukta Chakraborty, Sarnath Singh, Abraham Mittelman, Raj K. Tiwari. Human endothelial progenitor cells: A new target for anti-vascular therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 793. doi:10.1158/1538-7445.AM2017-793

Ferulic acid, a bioactive component of rice bran, improves oxidative stress and mitochondrial biogenesis and dynamics in mice and in human mononuclear cells

The aim of the study was to characterize the vascular effects of rice bran enzymatic extract (RBEE). ApoE−/− mice were fed a high-fat/cholesterol diet (HFD) or HFD supplemented with 5% RBEE for 21 weeks. RBEE prevented development of atherosclerotic plaques and oxidative stress in mouse aorta as well as the down-regulation of markers of mitochondrial biogenesis. Analysis of the bioactive components identified ferulic acid (FA) as responsible component. In healthy human volunteers, FA intake reduced NADPH oxidase activity, superoxide release, apoptosis and necrosis in peripheral blood mononuclear cells. Differentiation and proliferation of endothelial progenitor cells were improved. In summary, the study identifies FA as a major active component of rice bran, which improves expression of mitochondrial biogenesis and dynamics markers and reduces oxidative stress in a mouse model of vascular damage as well as in endothelial cells and human mononuclear cells.

Layer-by-layer bioassembly of cellularized polylactic acid porous membranes for bone tissue engineering.

The conventional tissue engineering is based on seeding of macroporous scaffold on its surface ("top-down" approach). The main limitation is poor cell viability in the middle of the scaffold due to poor diffusion of oxygen and nutrients and insufficient vascularization. Layer-by-Layer (LBL) bioassembly is based on "bottom-up" approach, which considers assembly of small cellularized blocks. The aim of this work was to evaluate proliferation and differentiation of human bone marrow stromal cells (HBMSCs) and endothelial progenitor cells (EPCs) in two and three dimensions (2D, 3D) using a LBL assembly of polylactic acid (PLA) scaffolds fabricated by 3D printing. 2D experiments have shown maintain of cell viability on PLA, especially when a co-cuture system was used, as well as adequate morphology of seeded cells. Early osteoblastic and endothelial differentiations were observed and cell proliferation was increased after 7 days of culture. In 3D, cell migration was observed between layers of LBL constructs, as well as an osteoblastic differentiation. These results indicate that LBL assembly of PLA layers could be suitable for BTE, in order to promote homogenous cell distribution inside the scaffold and gene expression specific to the cells implanted in the case of co-culture system.

A simply prepared small-diameter artificial blood vessel that promotes in situ endothelialization.

Synthetic grafts are of limited use in small-diameter vessels (Φ<6mm) due to the poor patency rate. The inability of such grafts to achieve early endothelialization together with the compliance mismatch between the grafts and the native vessels promote thrombosis, which eventually leads to graft occlusion. In the current study, stromal cell-derived factor (SDF)-1α/vascular endothelial growth factor (VEGF)-loaded polyurethane (PU) conduits were simply prepared via electrospinning. The mechanical property, drug release behavior and cytocompatibility of the conduits were investigated. The effects of the conduits on endothelial progenitor cell (EPC) mobilization and differentiation were examined in vitro. Then, the conduits were implanted as canine femoral artery interposition grafts. The results revealed that SDF-1α and VEGF were quickly released shortly after implantation, and the conduits exhibited slow and sustained release thereafter. The cytokines had definite effects on EPC mobilization and differentiation in vitro and promoted conduit endothelialization in vivo. The conduits had good tissue compatibility and favorable compliance. All of these features inhibited the conduits from being occluded, thereby improving their long-term patency rate. At 6th month postoperatively, 5 of the 8 grafts were patent while all the 8 grafts without the cytokines were occluded. These findings provide a simple and effective method for the construction of small-diameter artificial blood vessels with the aim of facilitating early endothelialization and improving long-term patency. STATEMENT OF SIGNIFICANCE: (1) SDF-1α/VEGF loaded PU conduits were simply prepared by electrospinning. The cytokines with definite and potent effects on angiogenesis were used to avoid complicated mechanism researches. Compared with most of the current vascular grafts which are of poor strength or elasticity, the conduits have favorable mechanical property. All of these inhibit the conduits from occlusion, and thus improve their long-term patency rate. (2) For the in vivo tests, the dogs did not receive any anticoagulant medication in the follow-up period to expose the grafts to the strictest conditions. In vivo endothelialization of the conduits was thoroughly investigated by Sonography, HE staining, SEM and LSCM. The study will be helpful for the construction of small-diameter artificial blood vessels.

An effective ex-vivo approach for inducing endothelial progenitor cells from umbilical cord blood CD34+ cells

BackgroundTransplantation of endothelial progenitor cells (EPCs)/endothelial cells (ECs) has been used for the treatment of ischemic diseases and hemophilia A, due to their great capacity for producing factor VIII and for repairing vascular damage. We established an effective approach to stimulate the expansion and differentiation of EPCs for potential therapeutic applications.MethodsCD34+ cells isolated from human cord blood were cultured in a two-step system for 21 days. The generated adherent cells were characterized via flow cytometry and immunofluorescent staining. Moreover, single-cell clonogenic and tube-forming assays were carried out to evaluate their potential to proliferate and form vessel networks. Furthermore, these cells were transplanted into a mouse model of hepatic sinusoidal endothelium injury by hepatic portal vein injection to investigate their in-vivo behavior.ResultsThe two-step culture protocol promoted the expansion and differentiation of human cord blood CD34+ cells efficiently, resulting in a large number of adherent cells within 3 weeks. The generated adherent cells were identified as EPCs/ECs based on the expression of CD31, CD144, vWF, and FVIII, and cell numbers showed a 1400-fold increase compared with the initial number. Moreover, these EPCs/ECs were capable of proliferating and establishing colonies as individual cells, and forming tube-like structures. More significantly, tissue examination of mice after transplantation revealed that the injected EPCs/ECs migrated and integrated into the liver, reconstituting the sinusoidal endothelial compartment.ConclusionsWe developed an approach for the generation of cord blood-derived EPCs/ECs on a large scale, characterized them phenotypically, and demonstrated their in-vivo functional capacity. Our approach provides an excellent source of healthy EPCs/ECs for use in cell therapy in a clinical setting.

Notch1 Impairs Endothelial Progenitor Cell Bioactivity in Preeclampsia.

Aberrant vasculature and endothelial dysfunction on both the maternal and the fetal side are thought to play a role in the pathogenesis of preeclampsia, a hypertensive complication during pregnancy. Endothelial progenitor cells (EPCs) have the capacity for endothelial repair. The Dll4/Notch signaling pathway suppresses the functions of EPCs in the pathogenesis of preeclampsia. Notch1 was found to be one of the specific receptors for ligands of the Delta 4 and play critical roles in angiogenesis. However, the roles of Notch1 with regard to EPCs and preeclampsia have yet to be completely characterized. The aim of this study is to determine whether Notch1 also has a negative influence on the regulation of EPC activity. Accordingly, we analyzed the differences between the preeclampsia group and the control group in terms of the number of EPCs and colony-forming units (CFUs) and their Notch1 expressions. The influence of the Notch1 signaling pathway on functions of EPCs was determined by repeating the assays in the presence of Notch1 downregulation. The number of EPCs and CFUs was significantly lower in patients with preeclampsia compared to healthy controls. Additionally, there was a notable increase in Notch1 expression in EPCs of patients with preeclampsia compared to controls. The downregulation of Notch1 promoted the proliferation, differentiation, migration, and adhesion of EPCs and the ability to form human umbilical vein endothelial cell tubes. These findings suggested that decrease and dysfunction of EPCs may be involved in the pathogenesis of preeclampsia. Inhibition of Notch1, which promoted EPC-mediated angiogenesis in vitro, may be an alternative therapeutic approach to promoting vasculogenesis in patients with preeclampsia.

"Obesity Paradox" in Heart Failure: The Possible Role of Progenitor Endothelial Cell Dysfunction

The “obesity paradox” phenomenon is referred to as a U-shaped curve between long-term prognosis and body mass index in heart failure patients. There is a large body of evidence regarding the regulatory role of visceral adipose tissue-related adipocytokines in activity of endogenous repair system. The reparation of myocardium and endothelium may strongly enhance by differentiation and mobbing of endothelial progenitor cells (EPCs). They improve angiogenesis and collateral vessel growth, as well as counteract vascular injury. It has suggested that several metabolic factors frequently associated with HF may increase the number of circulating EPCs, which mediate repair processes and collaborate with obese. In contrast, decreased number and/or weak functionality of EPCs relate with altered endogenous repair system and may negatively contribute in HF development. Finally, moving across recently received evidence “obesity paradox” could be elucidated as a result of interplaying of trigging repair systems and ability of EPCs to response on challenges enhancing reparative potency in target organs, i.e. myocardium, vascular wall and endothelium.

Mechanisms of Organ Injury and Repair by Macrophages.

Macrophages regulate tissue regeneration following injury. They can worsen tissue injury by producing reactive oxygen species and other toxic mediators that disrupt cell metabolism, induce apoptosis, and exacerbate ischemic injury. However, they also produce a variety of growth factors, such as IGF-1, VEGF-α, TGF-β, and Wnt proteins that regulate epithelial and endothelial cell proliferation, myofibroblast activation, stem and tissue progenitor cell differentiation, and angiogenesis. Proresolving macrophages in turn restore tissue homeostasis by functioning as anti-inflammatory cells, and macrophage-derived matrix metalloproteinases regulate fibrin and collagen turnover. However, dysregulated macrophage function impairs wound healing and contributes to the development of fibrosis. Consequently, the mechanisms that regulate these different macrophage activation states have become active areas of research. In this review, we discuss the common and unique mechanisms by which macrophages instruct tissue repair in the liver, nervous system, heart, lung, skeletal muscle, and intestine and illustrate how macrophages might be exploited therapeutically.

Method for in vitro differentiation of bone marrow mesenchymal stem cells into endothelial progenitor cells and vascular endothelial cells

Vascular development is a regulated process and is dependent on the participation and differentiation of many cell types including the proliferation and migration of vascular endothelial cells and differentiation of endothelial progenitor cells (EPCs) to mesodermal precursor cells. Thus, reconstitution of this process in vitro necessitates providing ambient conditions for generating and culturing EPCs in vitro and differentiating them to vascular endothelial cells. In the present study, we developed methods to differentiate bone marrow mesenchymal stem cells (MSC) into EPCs and to vascular endothelial cells. Bone marrow MSC from canines and human sources were differentiated in vitro in to EPCs. These EPCs were able to express a variety of endothelial markers following 7 days in culture. Further culturing led to the appearance of an increased number and proportion of endothelial cells. These cells were stable even after 30 generations in culture. There was a gradual loss of CD31 and increased expression of factor VIII, VEGFR and CD133. VEGF being highly angiogenic, helps in the vascular development. These results provide the basis for the possible development of vasculature in vitro conditions for biomedical applications and in vivo for organ/tissue reconstruction therapies.

Jagged-1 Signaling in the Bone Marrow Microenvironment Promotes Endothelial Progenitor Cell Expansion and Commitment of CD133+ Human Cord Blood Cells for Postnatal Vasculogenesis.

Notch signaling is involved in cell fate decisions during murine vascular development and hematopoiesis in the microenvironment of bone marrow. To investigate the close relationship between hematopoietic stem cells and human endothelial progenitor cells (EPCs) in the bone marrow niche, we examined the effects of Notch signals [Jagged-1 and Delta-like ligand (Dll)-1] on the proliferation and differentiation of human CD133+ cell-derived EPCs. We established stromal systems using HESS-5 murine bone marrow cells transfected with human Jagged-1 (hJagged-1) or human Dll-1 (hDll-1). CD133+ cord blood cells were co-cultured with the stromal cells for 7 days, and then their proliferation, differentiation, and EPC colony formation was evaluated. We found that hJagged-1 induced the proliferation and differentiation of CD133+ cord blood EPCs. In contrast, hDll-1 had little effect. CD133+ cells stimulated by hJagged-1 differentiated into CD31+/KDR+ cells, expressed vascular endothelial growth factor-A, and showed enhanced EPC colony formation compared with CD133+ cells stimulated by hDll-1. To evaluate the angiogenic properties of hJagged-1- and hDll-1-stimulated EPCs in vivo, we transplanted these cells into the ischemic hindlimbs of nude mice. Transplantation of EPCs stimulated by hJagged-1, but not hDll-1, increased regional blood flow and capillary density in ischemic hindlimb muscles. This is the first study to show that human Notch signaling influences EPC proliferation and differentiation in the bone marrow microenvironment. Human Jagged-1 induced the proliferation and differentiation of CD133+ cord blood progenitors compared with hDll-1. Thus, hJagged-1 signaling in the bone marrow niche may be used to expand EPCs for therapeutic angiogenesis.

Abstract 13863: PGC-1α Mediates Differentiation Arrest of Murine Bone Marrow-derived Endothelial Progenitor Cells in Diabetes

Introduction: Endothelial progenitor cells (EPCs) in murine bone marrow lineage-negative c-kit+Sca-1+ (BM-KSL) fraction are mobilized in circulation upon tissue injury to mediate a neovascularization process called vasculogenesis, which requires proper differentiative capacity of EPCs. Diabetics suffer defective vasculogenesis, a substantial mechanism for diabetic angiopathy in ischemic limb and heart. How it occurs, however, remains largely unknown. We recently demonstrated that type 1 (T1) and T2 diabetes (DM) induces a transcriptional coactivator PGC-1α in endothelial cells (ECs), and that EC PGC-1α mediates impaired cell migration and angiogenesis in DM. PGC-1α was also found to increase in EPCs cultivated from T2DM patients PB-MNCs. Building on these, we hypothesized roles for PGC-1α in EPC dysfunction. Methods and Results: We used Tie2-Cre-driven PGC-1α conditional null mice (KO), with or without T1DM induction by streptozocine. DM increased PGC-1α mRNA in WT BM-KSL cells whereas this induction was blocked in KO cells. DM decreased the differentiation capacity of WT BM-KSL cells and PB-MNCs, as determined by the formation of primitive (pEPC) and definitive (dEPC) colonies. PGC-1α ablation in KO rescued the defective EPCs differentiation in DM, most notably PB-MNCs formation of dEPC colonies, the known vasculogenic population. Consistent with this, endothelial marker gene expression (KDR, CD31, vWF), EPCs abundance, and EPCs vasculogenic functions of PB-MNCs was blunted by DM but rescued by PGC-1α ablation in KO. Importantly, T2DM induction by high-fat diet feeding also caused reduction in the EPCs abundance and EC gene expression of PB-MNCs, which was rescued by PGC-1α ablation in KO. Conclusions: Our data demonstrate critical new roles for PGC-1α in vasculogenesis. PGC-1α mediates the vasculogenic differentiation defect of circulating EPCs in T1 and T2 DM, in sharp contrast to the anti-migratory effect of EC PGC-1α in mediating diabetic angiostasis. Our data broadens the relevance of PGC-1α in the etiology of diabetic angiopathy, now with a potential to therapeutically restore EPCs vasculogenicity, and may provide an opportunity to improve the efficacy of autologous adoptive EPC therapy for limb and myocardial ischemia in DM.

Dynamic Perfusion Culture of Human Outgrowth Endothelial Progenitor Cells on Demineralized Bone Matrix In Vitro.

BackgroundThe aim of this study was to investigate the proliferation, differentiation, and tube formation of human outgrowth endothelial progenitor cells (OECs) cultured with porous demineralized bone matrix (DBM) under a dynamic perfusion system in vitro.Material/MethodsOECs were isolated, expanded, characterized, eGFP-transfected and seeded on DBM scaffold and cultured under static or dynamic perfusion conditions, and continuously observed under fluorescence microscope. DBM scaffolds were harvested on day six for RT-PCR and western blot assay to analyze the mRNA and protein expression level of CD34, VE-cadherin, and VEGF. Scanning electron microscope (SEM) was used to observe the tube formation of OECs seeded on DBM scaffolds.ResultsThe results showed the cell density of OECs on DBM was higher when exposed to shear stress generated by a dynamic perfusion system. Shear stress also markedly increased the expression level of VE-cadherin and VEGF and decreased the expression of CD34, at both mRNA and protein levels. SEM showed that the shear-stressed OECs formed tube-like structures inside the pores of DBM scaffolds.ConclusionsA dynamic perfusion system can be used as an innovative method for the rapid vascularization in tissue engineering, which can accelerate the proliferation and differentiation of OECs and the vascularization of implanted scaffolds.

Impaired development and dysfunction of endothelial progenitor cells in type 2 diabetic mice

AimDysfunction of circulating endothelial progenitor cells (EPCs) has been shown to affect the development of microvascular diseases in diabetes patients. The aim of this study was to elucidate the development and mechanical dysfunction of EPCs in type 2 diabetes (T2D). MethodsThe colony-forming capacity of EPCs and differentiation potential of bone marrow (BM) c-Kit(+)/Sca-I(+) lineage-negative mononuclear cells (KSL) were examined in T2D mice, db/db mice and KKAy mice, using EPC colony-forming assay (EPC-CFA). ResultsT2D mice had fewer BM stem/progenitor cells, and proliferation of KSL was lowest in the BM of db/db mice. In T2D mice, the frequency of large colony-forming units (CFUs) derived from BM-KSL was highly reduced, indicating dysfunction of differentiation into mature EPCs. Only a small number of BM-derived progenitors [CD34(+) KSL cells], which contribute to the supply of EPCs for postnatal neovascularization, was also found. Furthermore, in terms of their plasticity to transdifferentiate into various cell types, BM-KSL exhibited a greater potential to differentiate into granulocyte macrophages (GMs) than into other cell types. ConclusionT2D affected EPC colony formation and differentiation of stem cells to mature EPCs or haematopoietic cells. These data suggest opposing regulatory mechanisms for differentiation into mature EPCs and GMs in T2D mice.

Regulatory roles of interferon-inducible protein 204 on differentiation and vasculogenic activity of endothelial progenitor cells.

BackgroundEndothelial progenitor cells (EPCs) have shown great potential in angiogenesis either by their differentiation into endothelial cells or by secretion of angiogenic factors. Interferon-inducible protein 204 (Ifi204) has been reported to participate in the regulation of cell growth and differentiation. However, its role in differentiation of EPCs remains unknown. We proposed that Ifi204 could modulate the differentiation and regenerative abilities of EPCs.MethodsIfi204-expressing lentivirus and Ifi204 siRNA were introduced into EPCs to overexpress and suppress the expression of Ifi204. Using fluorescence-activated cell sorting, immunocytochemistry, and quantitative PCR, endothelial markers including CD31, VE-cadherin, and vWF were detected in the modified EPCs. An in-vitro incorporation assay and a colony-forming assay were also performed.ResultsEvidence showed that Ifi204 inhibition decreased the endothelial differentiation and vasculogenic activities of EPCs in vitro. In mice with hindlimb ischemia, downregulation of Ifi204 in EPCs, which was tracked by our newly synthesized nanofluorogen, impaired neovascularization, with a corresponding reduction in hindlimb blood reperfusion by postoperative day 14.ConclusionsIfi204 is required for EPC differentiation and neovascularization in vitro and in vivo. The regulatory roles of Ifi204 in EPC differentiation may benefit the clinical therapy of ischemic vascular diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0365-5) contains supplementary material, which is available to authorized users.

Dysfunction of endothelial progenitor cells is associated with the type I IFN pathway in patients with polymyositis and dermatomyositis.

Alterations in phenotype and function of endothelial progenitor cells (EPCs) have been associated with poor vascular outcomes and impaired vascular repair in various conditions. Our hypothesis was that patients with PM and DM have dysregulation of EPCs driven by type I IFN and IL-18 similar to other autoimmune diseases. Quantification of circulating EPCs was performed by flow cytometry in patients with PM/DM and matched healthy controls. The ability of EPCs to differentiate into mature endothelial cells was investigated by light and fluorescence microscopy quantification in the presence or absence of PM/DM or control serum, neutralizing antibodies to type I IFN receptor or IL-18. Serum type I IFN activity was quantified by induction of type I IFN-inducible genes in HeLa cells. Circulating IL-18 concentrations were assessed by ELISA. Circulating EPCs were significantly lower in PM/DM patients compared with controls. PM/DM EPCs displayed a decreased capacity to differentiate into mature endothelial cells and PM/DM serum significantly inhibited differentiation of control EPCs. This effect was reversed in the majority of samples with neutralizing antibodies to IL-18 or to type I IFN receptor or by a combination of these antibodies. Patients with associated impairments in EPC function had higher type I IFN serum activity. PM/DM is associated with dysregulation of EPC phenotype and function that may be attributed, at least in part, to aberrant IL-18 and type I IFN pathways. The implication of these vasculopathic findings for disease prognosis and complications remains to be determined.

Antiangiogenic and Antitumor Activities of Aflibercept, a Soluble VEGF Receptor-1 and -2, in a Mouse Model of Hepatocellular Carcinoma

BACKGROUND & AIM: Aflibercept known as ziv-aflibercept in the United States is a soluble decoy receptor of both vascular endothelial growth factor (VEGF) receptor-1 and -2 known to inhibit the binding of VEGF and placental growth factor (PlGF) to VEGF receptor-1 and -2. Here, we analyzed the mechanisms of the antitumor effects of aflibercept in mouse hepatoma models. METHODS: In in vitro studies, we determined the effects of aflibercept on human umbilical vein cell (HUVEC) proliferation and bone marrow (BM) cell differentiation to endothelial progenitor cells (EPCs). In in vivo experiments, aflibercept was injected intraperitoneally in hepatoma cell tumor-bearing mice, and its inhibitory effects on tumor growth and BM cell migration to tumor tissues were evaluated. RESULTS: Aflibercept suppressed phosphorylation of VEGF receptor-1 and -2 in HUVEC and dose-dependently inhibited VEGF-induced HUVEC proliferation. It suppressed the differentiation of BM cells to EPCs and migration of BM cells to tumor tissues. It also suppressed tumor growth and prolonged survival time of tumor-bearing mice without side effects. In tumor tissues, aflibercept upregulated the expression of hypoxia inducible factor1-α, VEGF, PlGF, fibroblast growth factor-2, platelet derived growth factor-BB, and transforming growth factor-α and reduced microvascular density. It also reduced sinusoidal density in noncancerous liver tissues. CONCLUSIONS: Our results demonstrated potent antitumor activity for aflibercept in a mouse model of hepatocellular carcinoma. These effects were mediated through inhibition of neovascularization, caused by inhibition of endothelial cell proliferation, EPC differentiation, and BM cell migration to tumor tissues.

Endothelial progenitor cells are differentially impaired in ANCA-associated vasculitis compared to healthy controls.

BackgroundEndothelial progenitor cells (EPC) are of major importance in vascular repair under healthy circumstances. Vascular injury in need of repair occurs frequently in ANCA-associated vasculitis (AAV). A specialized T cell subset enhancing EPC function and differentiation has recently been described. These angiogenic T cells (Tang) may have an important impact on the vascular repair process. Therefore, the aim of our study was to investigate EPC and Tang in AAV.MethodsFifty-three patients suffering from AAV and 29 healthy controls (HC) were enrolled in our study. Forty-four patients were in remission, nine patients were in active state of disease. Patients were either untreated or were under monotherapy with low-dose steroids (max. 5 mg/day) at the time of sampling. Circulating EPC and Tang were determined by flow cytometry (FACS). The functional capacity of EPC was assessed by established cell culture methods.ResultsCirculating EPC were significantly decreased in AAV as compared to HC. The capacity of EPC to differentiate and proliferate was differentially impaired in patients as compared to HC. The outgrowth of endothelial colony-forming cells (ECFC) was severely decreased in patients whereas colony-forming units-endothelial cell (CFU-EC) outgrowth was unaffected. ECFC and CFU-EC differentiation was strictly T cell-dependent. Patients with a relapsing disease course had an impaired ECFC outgrowth and expansion of Tang as compared to patients with a stable, nonrelapsing disease.ConclusionsThe differentiation process of EPC is impaired in AAV. This may favor insufficient vascular repair promoting a relapsing disease course. Finally, these factors may explain a higher cardiovascular morbidity as has been previously documented in AAV.