Endothelial Cell Survival Research Articles

Inhibition of protein glycosylation is a novel pro-angiogenic strategy that acts via activation of stress pathways

Endothelial cell (EC) metabolism is thought to be one of the driving forces for angiogenesis. Here we report the identification of the hexosamine D-mannosamine (ManN) as an EC mitogen and survival factor for bovine and human microvascular EC, with an additivity with VEGF. ManN inhibits glycosylation in ECs and induces significant changes in N-glycan and O-glycan profiles. We further demonstrate that ManN and two N-glycosylation inhibitors stimulate EC proliferation via both JNK activation and the unfolded protein response caused by ER stress. ManN results in enhanced angiogenesis in a mouse skin injury model. ManN also promotes angiogenesis in a mouse hindlimb ischemia model, with accelerated limb blood flow recovery compared to controls. In addition, intraocular injection of ManN induces retinal neovascularization. Therefore, activation of stress pathways following inhibition of protein glycosylation can promote EC proliferation and angiogenesis and may represent a therapeutic strategy for treatment of ischemic disorders.

Local uncoordinated gene 5H2 contributes to nerve injury-induced mechanical allodynia associated to its role in autophagy.

Lesions of the peripheral nerves can lead to lifelong neuropathic pain (NP). Autophagic deficiency in the Schwann cells (SCs) is an early event in the origin of NP chronification. Uncoordinated gene 5H2 (UNC5H2), one of the repulsive netrin receptors, mediated the effect of netrin-1 on autophagic activation and cell survival in endothelial cells. However, its role on autophagy regulation in peripheral nerves during NP process remains unidentified. Chronic constriction injury (CCI) of the left sciatic nerve was induced in Sprague-Dawley rats, and UNC5H2 small interfering RNA was transfected to the ipsilateral sciatic nerve immediately after injury. Mechanical allodynia was assessed. Sciatic UNC5H2 and netrin-1 protein levels were investigated. Autophagy in the ipsilateral sciatic nerves was evaluated by detecting punctate light chain 3(LC3) and autophagosomes, as well as the levels of LC3 II, p62 and phosphorylated UNC51-like kinase (ULK1). After CCI, UNC5H2 of the sciatic nerves was upregulated, exclusively expressed in SCs. Small interfering RNA transfection resulted in significant decrease of UNC5H2 and netrin-1 protein, leading to exaggeration of mechanical allodynia through 14days after CCI. Autophagy was activated but autophagic influx was interfered within a week after CCI, shown by the elevated levels of both LC3II and p62, which was further deteriorated with UNC5H2 knockdown. In addition, the injury-induced augmentation of phosphorylated ULK1 was significantly diminished by UNC5H2 knockdown. Altogether, the results suggest that local UNC5H2 of the peripheral nerve plays a significant role in the process of injury-induced mechanical allodynia, probably associated to its contribution to autophagic regulation.

Abstract 17239: miRNAs Secreted by Exosomes Derived From Adipose Tissue Mesenchymal Stem Cells Overexpressing GATA-4 Increase Endothelial Cell Survival and Promote Angiogenesis

Exosomes (EXO) secreted from stem cells play a critical role in cell based therapy and appear to have greater salutary therapeutic effects than whole cells. Our previous study showed that EXO produced by GATA-4-overexpressing mesenchymal stem cells (MSCs) significantly promoted angiogenesis and protected cardiomyocytes resulting in improved ischemic myocardial function. In the present studies, we compared the miR expression pattern and determined whether Exo GATA-4 delivered miRs particularly promoted angiogenesis. Methods and Results: EXO were collected from conditioned medium of adipose tissue derived MSCs that were transfected with GATA-4 (Exo GATA-4 ) or with vector-empty (Exo null ) using ultracentrifugation ( Fig A ). Functional analysis showed that Exo GATA-4 significantly increased tube formation, migration, and proliferation of human umbilical vein endothelial cells (HUVECs) compared to Exo null . MicroRNA-seq data showed that 7 of the 230 miRs found in EXO, were significantly upregulated in Exo GATA-4 ( Fig B ). To determine the effect of upregulated miRs on Exo GATA-4 mediated angiogenesis, miR-155 and miR-6240 mimic, inhibitor, and negative control were directly transferred into HUVECs. After 48 hours, HUVECs were harvested for measuring endothelial cell behavior. Transfection of miR-6240-mimic significantly increased HUVECs proliferation, tolerance against H 2 O 2 induced injury ( Fig C ), tube-like structure formation ( Fig D ) and cell migration ( Fig E ) compared to those transfected with negative control. Concurrently, no significant differences were found in proliferation, survival, and tube-like structure formation among the cells transfected with miR-155-mimic and negative control, although miR-155-mimic significantly increased cell migration. Conclusion: The upregulated miRs in Exo GATA-4 may variably regulate endothelial cell behavior and the role of various miRs needs to be investigated individually.

Abstract 15092: The Yin-yang of Bmpr2 and Ces1 in the Pulmonary Endothelium Aad Its Role in Pulmonary Arterial Hypertension

Background/Hypothesis: Pulmonary Arterial Hypertension (PAH) is a life-threatening disease characterized by loss of pulmonary microvessels and vascular remodeling. Loss of function BMPR2 mutations contribute to pulmonary endothelial cell (EC) apoptosis and oxidative stress, but their reduced penetrance suggests need for additional modifiers. Carboxylesterase1 (CES1) is endoplasmic reticulum (ER) enzyme responsible for detoxification, proteostasis, and redox balance. Similar to BMPR2 mutations, we found that loss of CES1 is associated with oxidative stress and apoptosis. In this study, we explore a plausible link between BMPR2 pathway and CES1 regulation in promoting EC survival and angiogenesis. Methods: PECs & lung tissue from healthy donors and PAH patients were obtained from PHBI. To induce oxidative stress, we used H 2 O 2 (100 μM) & methamphetamine HCl (METH, 0.5-2mM). Both siRNA and pharmacological approaches were used to inhibit BMPR2, Nrf2, and CES1 expression. Caspase and Matrigel assays were used to assess PEC survival and tube formation, respectively. Results: RNAseq of BMPR2-mutant PECs showed significantly less CES1 expression, which correlated with reduced protein expression in PEC lysates and within lung vascular lesions. In healthy PECs, BMP9 stimulation led to increase in CES1 expression that was absent post BMPR2 knockdown. CES1 gene transcription was by BMPR2-dependent activation of Nrf2, a transcription factor responsible for antioxidant gene expression and mitochondrial biogenesis. Inhibition of Nrf2 activation by ML385 (5μM) abrogates BMP9 induced CES1 mRNA levels similar to BMPR2 knockdown. The connection between BMPR2 and CES1 was further strengthened by CES1 knockdown studies in PECs that demonstrated reduction in BMPR2 protein synthesis associated with ER stress and reduced autophagy. Finally, lung examination in CRISPR generated CES1 +/- mice demonstrated increased microvascular muscularization at normoxia compared to wild type mice. Conclusion: BMPR2 and CES1 are part of common signaling pathway that protects PECs against oxidative stress and mitochondrial damage through a positive feedback loop. Interventions that restore CES1 activity could rescue BMPR2 signaling and serve as novel PAH therapeutics.

Molecular Bases of VEGFR-2-Mediated Physiological Function and Pathological Role.

The vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) play crucial roles in vasculogenesis and angiogenesis. Angiogenesis is an important mechanism in many physiological and pathological processes, and is involved in endothelial cell proliferation, migration, and survival, then leads to further tubulogenesis, and finally promotes formation of vessels. This series of signaling cascade pathways are precisely mediated by VEGF/VEGFR-2 system. The VEGF binding to the IgD2 and IgD3 of VEGFR-2 induces the dimerization of the receptor, subsequently the activation and trans-autophosphorylation of the tyrosine kinase, and then the initiation of the intracellular signaling cascades. Finally the VEGF-activated VEGFR-2 stimulates and mediates variety of signaling transduction, biological responses, and pathological processes in angiogenesis. Several crucial phosphorylated sites Tyr801, Try951, Try1175, and Try1214 in the VEGFR-2 intracellular domains mediate several key signaling processes including PLCγ-PKC, TSAd-Src-PI3K-Akt, SHB-FAK-paxillin, SHB-PI3K-Akt, and NCK-p38-MAPKAPK2/3 pathways. Based on the molecular structure and signaling pathways of VEGFR-2, the strategy of the VEGFR-2-targeted therapy should be considered to employ in the treatment of the VEGF/VEGFR-2-associated diseases by blocking the VEGF/VEGFR-2 signaling pathway, inhibiting VEGF and VEGFR-2 gene expression, blocking the binding of VEGF and VEGFR-2, and preventing the proliferation, migration, and survival of vascular endothelial cells expressing VEGFR-2.

Emerging Role of Adipocyte Dysfunction in Inducing Heart Failure Among Obese Patients With Prediabetes and Known Diabetes Mellitus.

Adipose tissue dysfunction is a predictor for cardiovascular (CV) events and heart failure (HF) in patient population with obesity, metabolic syndrome, and known type 2 diabetes mellitus. Previous preclinical and clinical studies have yielded controversial findings regarding the role of accumulation of adipose tissue various types in CV risk and HF-related clinical outcomes in obese patients. There is evidence for direct impact of infiltration of epicardial adipocytes into the underlying myocardium to induce adverse cardiac remodeling and mediate HF development and atrial fibrillation. Additionally, perivascular adipocytes accumulation is responsible for release of proinflammatory adipocytokines (adiponectin, leptin, resistin), stimulation of oxidative stress, macrophage phenotype switching, and worsening vascular reparation, which all lead to microvascular inflammation, endothelial dysfunction, atherosclerosis acceleration, and finally to increase in CV mortality. However, systemic effects of white and brown adipose tissue can be different, and adipogenesis including browning of adipose tissue and deficiency of anti-inflammatory adipocytokines (visfatin, omentin, zinc-α2-glycoprotein, glypican-4) was frequently associated with adipose triglyceride lipase augmentation, altered glucose homeostasis, resistance to insulin of skeletal muscles, increased cardiomyocyte apoptosis, lowered survival, and weak function of progenitor endothelial cells, which could significantly influence on HF development, as well as end-organ fibrosis and multiple comorbidities. The exact underlying mechanisms for these effects are not fully understood, while they are essential to help develop improved treatment strategies. The aim of the review is to summarize the evidence showing that adipocyte dysfunction may induce the onset of HF and support advance of HF through different biological mechanisms involving inflammation, pericardial, and perivascular adipose tissue accumulation, adverse and electrical cardiac remodeling, and skeletal muscle dysfunction. The unbalancing effects of natriuretic peptides, neprilysin, and components of renin–angiotensin system, as exacerbating cause of altered adipocytokine signaling on myocardium and vasculature, in obesity patients at high risk of HF are disputed. The profile of proinflammatory and anti-inflammatory adipocytokines as promising biomarker for HF risk stratification is discussed in the review.

Long non-coding RNA TERRA influences DNA damage and survival of endothelial cells and cardiomyocytes

Abstract Ageing is the major risk factor for cardiovascular disease. Current therapies are mainly based on proteins, while targeting long non-coding RNAs (lncRNAs) is largely unexplored. Long non-coding RNAs are emerging as novel regulators of cellular functions and contributors to cardiovascular ageing. Although telomeres are heterochromatic regions, non-coding transcripts called Telomeric repeat-containing RNA (TERRA) are transcribed from the telomeres of most chromosomes. The transcription of TERRA starts at the subtelomere and ends in the telomere, leading to molecules of 0.2–10kb. This study aims to characterize the role of TERRA in the cardiovascular system. TERRA molecules from different chromosomes were upregulated in the hearts of old mice compared to young mice (p=0.002). An increased TERRA expression was also shown in heart tissue of patients with ischemic heart disease compared to donor heart tissue (p=0.001). In vitro an upregulation of the TERRA molecule transcribed from chromosome 20 (h20q-TERRA) was found in old passage human umbilical vein endothelial cells (HUVECs) (P15–17) compared to young HUVECs (P3) (p=0.014). IPSC-derived cardiomyocytes also increased the expression of h20q-TERRA with increasing passage (p=0.011). After knockdown of h20q-TERRA with LNA GapmeRs HUVECs show less sprout formation in a spheroid assay compared to negative control transfected HUVECs (p=0.002), without showing a change in migration (p=0.205) or proliferation (p=0.114). H20q-TERRA knockdown revealed that there was more apoptosis (p=0.015), more DNA damage as measured with the comet assay (p<0.001), increased γH2AX levels (p=0.029) and an increase in γH2AX colocalization with the telomere (p=0.011). The amount of phosphorylated P53 was also increased after knockdown (p=0.038), while it was decreased after TERRA overexpression (p=0.001). Inhibition of the ATM-yH2AX-P53 pathway did however not reduce the increased apoptosis after knockdown (KU60019 p=0.399; siP53 p=0.303). Silencing the m18-TERRA molecule in mouse endothelial H5V cells led to an increase in caspase activity (p=0.004) similar to what was shown in HUVECs. In addition, increased caspase activity (p=0.012), increased γH2AX levels (p<0.001) and increased γH2AX colocalization with the telomere (p=0.007) was also shown after silencing of h20q-TERRA in human cardiomyocytes. In summary, our data demonstrates that TERRA is upregulated with ageing and plays a role in endothelial and cardiomyocyte function and survival. These data show that TERRA transcripts are induced in cardiovascular ageing and are essential for endothelial cell function. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): Horizon 2020

The unexpected role of PI3-kinase gamma in pulmonary hypertension

Abstract Introduction Pulmonary hypertension (PH) is a pulmonary vascular disease that is associated with unacceptably high morbidity and mortality. PH is characterized by chronically increased pulmonary arterial pressure, increased pulmonary vascular resistance and right ventricular (RV) dysfunction and hypertrophy. Underlying mechanisms include increased proliferation and reduced apoptosis of both vascular smooth muscle cells (SMC) and endothelial cells (EC), as well as dysregulated immune responses. We have previously shown that class IA phosphatidylinositol-3-kinase (PI3K) isoforms, activated via receptor tyrosine kinases, are critically involved in the pathogenesis of PH. However, recent findings suggest that the class IB isoform PI3Kγ, which is activated downstream of G protein coupled receptors, is also important. It has been shown that PI3Kγ is involved in numerous processes that promote both vascular remodelling and maladaptive cardiac hypertrophy, including leukocyte recruitment, expression of proinflammatory chemokines and cytokines, as well as SMC and EC proliferation and survival. Therefore, the aim of our study was to investigate the role of PI3Kγ in the pathogenesis of PH. Methods The impact of PI3Kγ on the pathogenesis of PH was analysed in vivo using mice expressing a catalytically inactive form of PI3Kγ (PI3KγKD/KD) in the hypoxia-induced mouse model of PH. Mice were kept at 10%O2 (HOX) for 21 days or left under normoxic conditions (NOX). Subsequently, systolic right ventricular pressure (RVSP) was measured with a pressure catheter. RV hypertrophy was expressed as the ratio of RV weight to left ventricular + septum weight. Migration and proliferation of human pulmonary arterial SMC (hPASMC) as well as EC (hMVEC) were analysed using a PI3Kγ isoform-specific inhibitor (AS605240 [0.1; 0.3; 1μM]). Chemotaxis was determined by means of a modified Boyden chamber, and proliferation was quantified by a Bromodeoxyuridine (BrdU) incorporation assay. Results Whereas PI3Kγ inactivation had no effect on NOX animals, hypoxia led to increased RVSP and RV hypertrophy in WT animals (34.67±2.02 mmHg; 0.38±0.087) which were unexpectedly further increased in PI3KγKD/KD mice (37.67±1.3 mmHg, p=0.0104 vs. HOX WT; 0.47±0.06, p=0.0155 vs. HOX WT). Heart rate and systemic blood pressure remained unchanged. Inhibition of PI3Kγ by means of AS605240 did not affect proliferation of hPASMC and hMVEC, induced by multiple stimuli (FCS [10%], PDGF-BB [30ng/ml], or CXCL12 [100ng/ml], VEGF [50ng/ml]), respectively. However, FCS-induced migration of these cells was significantly reduced by AS605240 [0.3μM] (p<0.05). Conclusion Contrary to our expectations, the results show that kinase inactivation of PI3Kγ was not able to attenuate the pathogenesis of PH, but surprisingly led to a significant increase without critically changing cellular responses of SMC and EC. Therefore, our results indicate an unexpected protective effect of PI3Kγ on PH. Funding Acknowledgement Type of funding source: None

Upregulation of C-Reactive Protein by Placenta-Derived Mesenchymal Stem Cells Promotes Angiogenesis in A Rat Model with Cirrhotic Liver.

Background and ObjectivesLiver cirrhosis is accompanied by abnormal vascular shunts. The Wnt pathway is essential for endothelial cell survival and proliferation. C-reactive protein (CRP), which is produced by hepatocyte, activates angiogenesis in cardiovascular diseases.Methods and ResultsThe expression of CRP in CCl4-injured rat livers was detected using qRT-PCR and Western blotting after transplantation of placenta-derived mesenchymal stem cells (PD-MSCs) into rats. To determine whether CRP functions in hepatic regeneration by promoting angiogenesis through the Wnt pathway, we detected VEGF and β-catenin in liver tissues and BrdU and β-catenin in hepatocytes by immunofluorescence. The expression levels of CRP, Wnt pathway-related and angiogenic factors were increased in CCl4-injured and PD-MSCs transplanted rat livers. In vitro, the expression levels of Wnt signaling and angiogenic factors were decreased in siRNA-CRP-transfected rat hepatocytes.ConclusionsCRP upregulation by PD-MSCs participates in vascular remodeling to promote liver regeneration via the Wnt signaling pathway during hepatic failure.

Liraglutide reduces coronary endothelial cells no-reflow damage through activating MAPK/ERK signaling pathway

Coronary no-reflow damage is caused by endothelial cell damage although little drug is available to intervene in coronary no-reflow. Liraglutide is a kind of anti-diabetic drug and its cardioprotective role has been widely reported. In this study, we explored the role of liraglutide in regulating coronary endothelial cell damage. We used hydrogen peroxide to mimic coronary no-reflow damage in vitro. After exposure to hydrogen peroxide, endothelial cells’ viability was significantly reduced, an effect that was followed by an increase in cell apoptosis. Interestingly, liraglutide treatment obviously upregulated endothelial cell viability and thus prevented cell apoptosis. Further, we also found that liraglutide inhibited the activation of caspase-3 in hydrogen peroxide-treated endothelial cells. Besides, cellular metabolism, as reflected by mitochondrial membrane potential, was disrupted by hydrogen peroxide and reversed to normal levels with liraglutide. Further, we found that the ERK pathway is a potential downstream effector of liraglutide. Administration of liraglutide significantly promoted the activation of ERK and this effect may contribute to endothelial cell survival. Altogether, our results illustrated that hydrogen peroxide-mediated endothelial cell damage could be attenuated by liraglutide through modulation of the MAPK/ERK signaling pathway. This finding will pave a novel road for the intervention of coronary no-reflow damage in patients suffering from myocardial infarction.

Abstract A24: CD146-Rictor interaction reveals a pathway linking mTORC2 activation with extracellular stimuli

Abstract In all eukaryotes, the mechanistic target of rapamycin (mTOR) signaling emerges as a master regulator of homeostasis, which integrates environmental inputs to regulate many fundamental cellular processes such as cell growth and metabolism. The mTOR signaling functions through two structurally and functionally distinct complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which correspond to two major branches of signal output. However, it remains enigmatic how extracellular stimuli regulates mTOR signaling, particularly for mTORC2. Here, we demonstrate that in human umbilical vein endothelial cells (HUVEC), vascular endothelial growth factor (VEGF) promotes the activation of mTORC2 signaling, exhibited as phosphorylation of Akt /PKCα/SGK1. Cell adhesion molecule CD146, as VEGFR2 co-receptor, plays the pivotal role in mediating mTORC2 activation in response to VEGF. Deletion of CD146 resulted in dramatic reduction in mTORC2 activity, without affecting other PI3K/Akt/mTOR signaling pathways, such as mTORC1 and PI3K/PDK1, indicating that CD146 specifically regulates mTORC2 activity. By means of co-immunoprecipitation (co-IP) assay, CD146 is bestowed to interact with Rictor via its juxta-membrane KKGK motif upon VEGF stimulation, CD146-Rictor (mTORC2) interaction not only stabilizes Rictor from ubiquitin-proteasome-mediated degradation but also activates mTORC2 signaling, thus promoting VEGF-induced endothelial cell proliferation and survival. Collectively, our findings have identified a previously unanticipated mechanism by which mTORC2 signaling pathway is directly under the control of extracellular stimuli, linking environmental cues with mTORC2 activity, and implicate that targeting CD146-mTORC2 axis might be a novel strategy for diseases driven by uncontrolled cell proliferation. Citation Format: Wenyi Xu, Yongting Luo, Wei Cui. CD146-Rictor interaction reveals a pathway linking mTORC2 activation with extracellular stimuli [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr A24.

Hypoxia induces the translocation of glucose transporter 1 to the plasma membrane in vascular endothelial cells

Glucose uptake and adenosine triphosphate (ATP) generation are important for the survival and growth of endothelial cells. An increase of glucose uptake under hypoxia was previously shown to be associated with the increased expression of glucose transporters (GLUTs). However, the regulation of GLUT trafficking to the cell surface has not been examined in detail. Here, we report the characterization of GLUT1 translocation to the plasma membrane during hypoxia in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were exposed to hypoxia (1% O2) for 12 h, which significantly induced GLUT1 expression and translocation to the plasma membrane. GLUT1 translocation was associated with a decrease of intracellular ATP by hypoxia. Decreasing ATP levels with antimycin-A and 2-deoxyglucose induced GLUT1 translocation under normoxia. The induction of hypoxia-inducible factor-1α under normoxia did not influence the cell surface expression of GLUT1 or cellular ATP concentration. Interestingly, the translocation of GLUT1 induced by hypoxia was inhibited by the ATP-sensitive potassium (KATP) channel inhibitor glibenclamide, while the mitochondrial KATP channel inhibitor 5-HD did not influence GLUT1 translocation during hypoxia. These observations indicate that a decrease of intracellular ATP triggers GLUT1 translocation to the plasma membrane and is mediated by KATP channels, which would contribute to glucose uptake in HUVECs during hypoxia.

Microtubule Stabilization Promotes Microcirculation Reconstruction After Spinal Cord Injury

Spinal cord microcirculation plays an important role in maintaining the function of spinal cord neurons and other cells. Previous studies have largely focused on the ability of microtubule stabilization to inhibit the fibroblast migration and promote axon regeneration after spinal cord injury (SCI). However, the effect of microtubule stabilization treatment on microcirculation reconstruction after SCI remains unclear. By using immunofluorescence, we found that microtubule stabilization treatment improved microcirculation reconstruction via increasing the number of microvessels, pericytes, and the perfused microvessels after SCI. To clarify the underlying mechanisms, rat brain microvascular endothelial cells and pericytes were subjected to glucose oxygen deprivation. By using flow cytometry and western blotting, we found that microtubule stabilization treatment inhibited apoptosis and migration of endothelial cells and pericytes but promoted proliferation and survival of endothelial cells and pericytes through upregulated expression of vascular endothelial growth factor A (VEGFA), VEGF receptor 2, platelet-derived growth factor-B (PDGFB), PDGF receptor β, and angiopoietin-1 after SCI. Taken together, this study provides evidence for the mechanisms underlying the promotion of microcirculation reconstruction after SCI by microtubule stabilization treatment. Importantly, this study suggests the potential of microtubule stabilization as a therapeutic target to reduce microcirculation dysfunction after SCI in the clinic.

Paracrine effect of human adipose-derived stem cells on lymphatic endothelial cells.

Aim: The proposal of this study was to evaluate, in vitro, the potential paracrine effect of human adipose-derived stem cells (hASCs) to promote lymphangiogenesis in lymphatic endothelial cells isolated from rat diaphragmatic lymphatic vessels. Materials & methods:ELISAon VEGFA, VEGFC and IL6 in hASC-conditioned medium; LYVE1 immunostaining; and gene expression of PROX1, VEGFR3, VEGFC, VEGFA and IL6 were the methods used. Results:In 2D culture, hASC-conditioned medium was able to promote lymphatic endothelial cell survival, maintenance of endothelial cobblestone morphology and induction to form a vessel-like structure.Conclusion: The authors' results represent in vitro evidence of the paracrine effect of hASCs on lymphatic endothelial cells, suggesting the possible role of hASC-conditioned medium in developing new therapeutic approaches for lymphatic system-related dysfunction such as secondary lymphedema.

Endothelial response boosted by platelet lysate: The involvement of calcium toolkit

Wound repair is a dynamic process during which crucial signaling pathways are regulated by growth factors and cytokines released by several kinds of cells directly involved in the healing process. However, the limited applications and heterogeneous clinical results of single growth factors in wound healing encouraged the use of a mixture of bioactive molecules such as platelet derivatives for best results in wound repair. An interesting platelet derivative, obtained from blood samples, is platelet lysate (PL), which has shown potential clinical application. PL is obtained from freezing and thawing of platelet-enriched blood samples. Intracellular calcium (Ca2+) signals play a central role in the control of endothelial cell survival, proliferation, motility, and differentiation. We investigated the role of Ca2+ signaling in the PL-driven endothelial healing process. In our experiments, the functional significance of Ca2+ signaling machinery was highlighted performing the scratch wound assay in presence of different inhibitors or specific RNAi. We also pointed out that the PL-induced generation of intracellular ROS (reactive oxygen species) via NOX4 (NADPH oxidase 4) is necessary for the activation of TRPM2 and the resulting Ca2+ entry from the extracellular space. This is the first report of the mechanism of wound repair in an endothelial cell model boosted by the PL-induced regulation of [Ca2+]i.

Analysis of Cell-seeded, Collagen-rich Hydrogel for Wound Healing.

Background:Our laboratory has previously developed a novel collagen-rich hydrogel (cHG), which significantly increases the speed of wound healing in diabetic rats.Methods:In this study, we examine the in vitro survival and migration of fibroblasts, endothelial cells, and adipose-derived stem cells in a novel cHG. Furthermore, we test the ability of adipose-derived stem cell–seeded cHG to support cell survival and accelerate healing in vivo.Results:In vitro, cell survival within the cHG was retained for 25 days. We were unable to detect cellular migration into, out of, or through cHG. In the in vivo model, bioluminescence of stem cells seeded within the cHG in diabetic rat wounds was detected until day 10. Rate of wound closure was higher for cHG plus adipose-derived stem cells versus control from day 2 until day 16 and significant on days 6, 8, and 12 (P < 0.05). This significant difference was also observed on day 16 by histology (P ≤ 0.05).Conclusions:We conclude that cHG is a good candidate for delivering adipose-derived stem cells, endothelial cells, and fibroblasts to wounds. Future studies will determine whether the delivery of combinations of different cell lines in cHG further enhances wound healing.

Streptococcus pneumoniae utilizes a novel dynamin independent pathway for entry and persistence in brain endothelium.

Adoption of an endocytosis route promoting safe intracellular trafficking is a pre-requisite for development of invasive diseases by Streptococcus pneumoniae (SPN). We aim to explore the contribution of various endocytic routes in internalization and survival of SPN in blood brain barrier (BBB), a key event in development of pneumococcal meningitis. Pneumococcal entry and survival in brain endothelial cells were evaluated following treatment with combinations of inhibitors to block multiple endocytosis pathways leaving a single entry port open. Entry of SPN into brain endothelium through a novel dynamin independent pathway dictates a separate downstream trafficking itinerary. This allows SPN to evade lysosomal degradation, potentially promoting safe transit across BBB, leading to development of meningitis.

Resveratrol Improves Bnip3-Related Mitophagy and Attenuates High-Fat-Induced Endothelial Dysfunction.

Statin treatment reduces cardiovascular risk. However, individuals with well-controlled low-density lipoprotein (LDL) levels may remain at increased risk owing to persistent high triglycerides and low high-density lipoprotein cholesterol. Because resveratrol promotes glucose metabolism and mitigates cardiovascular disorders, we explored its mechanism of protective action on high-fat-induced endothelial dysfunction. Human umbilical venous endothelial cells were treated with oxidized LDL (ox-LDL) in vitro. Endothelial function, cell survival, proliferation, migration, and oxidative stress were analyzed through western blots, quantitative polymerase chain reaction, ELISA, and immunofluorescence. ox-LDL induced endothelial cell apoptosis, proliferation arrest, and mobilization inhibition, all of which resveratrol reduced. ox-LDL suppressed the activities of mitochondrial respiration complex I and III and reduced levels of intracellular antioxidative enzymes, resulting in reactive oxygen species overproduction and mitochondrial dysfunction. Resveratrol treatment upregulated Bnip3-related mitophagy and prevented ox-LDL-mediated mitochondrial respiration complexes inactivation, sustaining mitochondrial membrane potential and favoring endothelial cell survival. We found that resveratrol enhanced Bnip3 transcription through hypoxia-inducible factor 1 (HIF1) and 5′ AMP-activated protein kinase (AMPK). Inhibition of AMPK and HIF1 abolished resveratrol-mediated protection of mitochondrial redox balance and endothelial viability. Together, these data demonstrate resveratrol reduces hyperlipemia-related endothelial damage by preserving mitochondrial homeostasis.

Abstract 1483: A novel anti-Tie2 antibody stabilizes vessel and increases tumor infiltrated lymphocytes

Abstract Objective: The delivery of drugs and immune cells into the tumor microenvironment is limited due to abnormal tumor vessel which is characterized as low oxygen concentration, low perfusion rate and leakage. It leads to diminish the efficacy of drugs and radiation therapy. Traditional anti-angiogenesis strategies attempt to reduce the tumor vascular supply, but their success is restricted by insufficient efficacy or development of resistance. To solve the problem, we try to using active vessel stabilizer, which can normalize the abnormal condition of tumor vessel. Background: Tie2 acts as cell-surface receptor for Ang1/Ang2 and regulates angiogenesis, endothelial cell survival, proliferation, migration, as well as maintenance of vascular quiescence. Especially, Ang1-Tie2 signaling pathway has been known to promote blood vessel maturation and stabilization. Methods: We have developed a series of novel human IgG monoclonal antibody that binds to human-TIE2 with a high affinity (Kd ~0.1 nM). The antibody binds to human TIE2 extracellular domain and activates its associated function in a ligand independent way. The mode of action was studied in vitro with human umbilical vein endothelial cells (HUVEC) and animal models. The vessel stabilization was investigated with laser induced choroidal neovascularization (CNV). The effect on tumor infiltrated lymphocyte was also studied in mouse colon cancer model. Results: Anti-Tie2 antibody increased human endothelial cell migration like Ang1 and inhibited VEGF-induced vascular leakage, contributing to vessel normalization. It binds to Tie2 in a ligand independent way and thus it can stabilize vessel as an agonist. Both p-VEGFR and p-VE-Cadherin levels are also significantly decreased on VEGF-induced VEGFR signaling pathway by anti-Tie2 antibody, suggesting that it can maintain cell to cell junction. The vessel stabilization effect was demonstrated in a mouse model of laser induced CNV. Moreover, in syngeneic CT26 mouse models, anti-Tie2 antibody showed anti-tumor effect in which it significantly reduced the tumor growth and synergistically when it combined with anti PD-1 antibody. The tumor infiltrating lymphocytes were increased in CT26 tumor, especially CD8+ T cells and MDSC when anti-Tie2 was administered. Conclusion: We developed active vessels stabilizer targeting Tie2, having an effect of vessel stabilization in a ligand independent way. It inhibited VEGF-induced vascular leakage through decrease of p-VEGFR and VE-cadherin. This active vessel stabilizer could help deliver drug and lymphocyte into the TME. The therapeutic efficacy of immune checkpoint inhibitors can be increased when it combined with this active vessel stabilizer. Thus, this active vessel stabilizer can change cold tumor into hot tumor. Citation Format: Eun-Ah Lee, Beomyong Park, Nu Ri Kang, Youngae Lee, Do-yun Kim, Sang Soon Byun, Jin Yong An, Cheon Ho Park, Weon Sup Lee, Joo Hyoung Lee. A novel anti-Tie2 antibody stabilizes vessel and increases tumor infiltrated lymphocytes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1483.

NEAT1/miR-140-3p/MAPK1 mediates the viability and survival of coronary endothelial cells and affects coronary atherosclerotic heart disease.

Studies have shown that long non-coding RNAs (lncRNA) play critical roles in coronary atherosclerotic heart disease (CAD). However, the function of lncRNA nuclear enriched abundant transcript 1 (NEAT1) in CAD is unclear. In this study, we aimed to investigate the functions of lncRNA NEAT1 in CAD. RT-PCR and western blot analysis were carried out to examine the expressions of related RNAs. Colony formation assay, cell proliferation assay, apoptosis assay, and dual-luciferase reporter assay were conducted to investigate the abilities of colony migration, cell proliferation, apoptosis, and targeting. The results showed that NEAT1 was up-regulated in CAD blood samples and in human coronary endothelial cells (HCAECs). Transfection of pcNEAT1 significantly inhibited the survival rate of HCAECs and induced apoptosis of HCAECs. MiR-140-3p was down-regulated in HCAECs. NEAT1 directly targeted miR-140-3p, and the expression of miR-140-3p was inversely correlated with the expression of NEAT1 in CAD patients. In addition, co-transfection of NEAT1 with miR-140-3p mimic reversed the effect of pcNEAT1 on cell viability and apoptosis. mitogen-activated protein kinase 1 (MAPK1) was proved to be a target gene of miR-140-3p, and the miR-140-3p mimic was shown to reduce the expression of MAPK1 in HCAECs. pcNEAT1 significantly increased the expression level of MAPK1, while shNEAT1 significantly reduced the expression level of MAPK1. Our results revealed that lncRNA NEAT1 increased cell viability and inhibited CAD cell apoptosis possibly by activating the miR-140-3p/MAPK1 pathway, and lncRNA NEAT1 might serve as a potential therapeutic target for CAD.