Smooth Muscle Cell Proangiogenic Phenotype Induced by Cyclopentenyl Cytosine Promotes Endothelial Cell Proliferation and Migration

Glucosamine-Mediated Hexosamine Biosynthesis Pathway Activation Uses ATF4 to Promote "Exercise-Like" Angiogenesis and Perfusion Recovery in PAD

BACKGROUND

Endothelial cells (ECs) use glycolysis to produce energy. In preclinical models of peripheral arterial disease, further activation of EC glycolysis was ineffective or deleterious in promoting hypoxia-dependent angiogenesis, whereas pentose phosphate pathway activation was effective. Hexosamine biosynthesis pathway, pentose phosphate pathway, and glycolysis are closely linked. Glucosamine directly activates hexosamine biosynthesis pathway.

METHODS

Hind-limb ischemia in endothelial nitric oxide synthase knockout (eNOS-/-) and BALB/c mice was used. Glucosamine (600 μg/g per day) was injected intraperitoneally. Blood flow recovery was assessed using laser Doppler perfusion imaging and angiogenesis was studied by CD31 immunostaining. In vitro, human umbilical vein ECs and mouse microvascular ECs with glucosamine, L-glucose, or vascular endothelial growth factor (VEGF165a) were tested under hypoxia and serum starvation. Cell Counting Kit-8, tube formation, intracellular reactive oxygen species, electric cell-substrate impedance sensing, and fluorescein isothiocyanate dextran permeability were assessed. Glycolysis and oxidative phosphorylation were assessed by seahorse assay. Gene expression was assessed using RNA sequencing, real-time quantitative polymerase chain reaction, and Western blot. Human muscle biopsies from patients with peripheral arterial disease were assessed for EC O-GlcNAcylation before and after supervised exercise versus standard medical care.

RESULTS

On day 3 after hind-limb ischemia, glucosamine-treated versus control eNOS-/- mice had less necrosis (n=4 or 5 per group). Beginning on day 7 after hind-limb ischemia, glucosamine-treated versus control BALB/c mice had higher blood flow, which persisted to day 21, when ischemic muscles showed greater CD31 staining per muscle fiber (n=8 per group). In vitro, glucosamine versus L-glucose ECs showed improved survival (n=6 per group) and tube formation (n=6 per group). RNA sequencing of glucosamine versus L-glucose ECs showed increased amino acid metabolism (n=3 per group). That resulted in increased oxidative phosphorylation (n=8-12 per group) and serine biosynthesis pathway without an increase in glycolysis or pentose phosphate pathway genes (n=6 per group). This was associated with better barrier function (n=6-8 per group) and less reactive oxygen species (n=7 or 8 per group) compared with activating glycolysis by VEGF165a. These effects were mediated by activating transcription factor 4, a driver of exercise-induced angiogenesis. In muscle biopsies from humans with peripheral arterial disease, EC/O-GlcNAcylation was increased by 12 weeks of supervised exercise versus standard medical care (n=6 per group).

CONCLUSIONS

In cells, mice, and humans, activation of hexosamine biosynthesis pathway by glucosamine in peripheral arterial disease induces an "exercise-like" angiogenesis and offers a promising novel therapeutic pathway to treat this challenging disorder.

Human cytomegalovirus pUL135 protein affects endothelial cell function via CD2AP in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a kind of pediatric vasculitis, whose pathogenesis has not been elucidated until now. Many scholars believe that KD is one type of infectious diseases in the susceptible groups. However, no recognized pathogens are confirmed. Human cytomegalovirus (HCMV) is a ubiquitous human herpes virus, which can infect varieties of cells including endothelial cells. Studies reported that the viral protein pUL135 is very important for virus replication, reactivation and immune escape. Therefore, we hypothesize that HCMV pUL135 may have a pathogenic effect on KD.

METHODS

We first determined pUL135 levels in the serum from KD patients. Next, we examined the effects and mechanisms of pUL135 on endothelial cell proliferation and migration. Finally, we assessed the effect of pUL135 on cardiac inflammation in a KD murine model.

RESULTS

Data showed that pUL135 level was significantly increased in the serum from KD patients compared with the healthy and fever controls. And pUL135 expression in endothelial cells remarkably inhibited cell proliferation, migration and tube formation. Moreover, expression of pUL135 obviously affected actin cytoskeleton. Mechanism investigation substantiated that pUL135 mediated endothelial cell dysfunction via regulating CD2AP. Ultimately, we found that HCMV pUL135 aggravated coronary arteritis in the Candida albicans cell wall extracts (CAWS)-induced KD mouse model.

CONCLUSION

Our findings imply that HCMV pUL135-mediated endothelial dysfunction plays an important role in exacerbating coronary artery injury in KD conditions.

The Impact of Developmental and Metabolic Cues on Cytoophidium Formation

The cytoophidium, composed mainly of CTP synthase (CTPS), is a newly discovered dynamic filamentous structure in various organisms such as archaea, bacteria, and humans. These filamentous structures represent a fascinating example of intracellular compartmentation and dynamic regulation of metabolic enzymes. Currently, cytoophidia have been proven to be tightly regulated and highly dynamic, responding rapidly to developmental and metabolic cues and playing a critical role in maintaining cellular homeostasis. In this review, we would like to discuss in detail the characteristics, mechanisms, functions, and potential applications of this conservative but promising organelle.

3D-Printed proangiogenic patches of photo-crosslinked gelatin and polyurethane hydrogels laden with vascular cells for treating vascular ischemic diseases

Engineering vascularized tissues remains a promising approach for treating ischemic cardiovascular diseases. The availability of 3D-bioprinted vascular grafts that induce therapeutic angiogenesis can help avoid necrosis and excision of ischemic tissues. Here, using a combination of living cells and biodegradable hydrogels, we fabricated 3D-printed biocompatible proangiogenic patches from endothelial cell-laden photo-crosslinked gelatin (EC-PCG) bioink and smooth muscle cell-encapsulated polyurethane (SMC-PU) bioink. Implantation of 3D-bioprinted proangiogenic patches in a mouse model showed that EC-PCG served as an angiogenic capillary bed, whereas patterned SMC-PU increased the density of microvessels. Moreover, the assembled patterns between EC-PCG and SMC-PU induced the geometrically guided generation of microvessels with blood perfusion. In a rodent model of hindlimb ischemia, the vascular patches rescued blood flow to distal tissues, prevented toe/foot necrosis, promoted muscle remodeling, and increased the capillary density, thereby improving the heat-escape behavior of ischemic animals. Thus, our 3D-printed vascular cell-laden bioinks constitute efficient and scalable biomaterials that facilitate the engineering of vascular patches capable of directing therapeutic angiogenesis for treating ischemic vascular diseases.

Enhanced Reendothelialization and Thrombosis Prevention with a New Drug-Eluting Stent

PURPOSE

The objective of the study is to test the efficacy of cyclopentenyl cytosine (CPEC)-coated stents on blocking artery stenosis, promoting reendothelialization, and reducing thrombosis.

METHODS

Scanning electron microscopy was employed to observe the morphological characteristics of stents coated with a mixture of CPEC and poly(lactic-co-glycolic acid) (PLGA) copolymer. PLGA has been used in various Food and Drug Administration (FDA)-approved therapeutic devices. In vitro release of CPEC was tested to measure the dynamic drug elution. Comparison between CPEC- and everolimus-coated stents on neointimal formation and thrombosis formation was conducted after being implanted into the human internal mammary artery and grafted to the mouse aorta.

RESULTS

Optimization in stent coating resulted in uniform and consistent coating with minimal variation. In vitro drug release tests demonstrated a gradual and progressive discharge of CPEC. CPEC- or everolimus-coated stents caused much less stenosis than bare-metal stents. However, CPEC stent-implanted arteries exhibited enhanced reendothelialization compared to everolimus stents. Mechanistically, CPEC-coated stents reduced the proliferation of vascular smooth muscle cells while simultaneously promoting reendothelialization. More significantly, unlike everolimus-coated stents, CPEC-coated stents showed a significant reduction in thrombosis formation even in the absence of ongoing anticoagulant treatment.

CONCLUSIONS

The study establishes CPEC-coated stent as a promising new device for cardiovascular interventions. By enhancing reendothelialization and preventing thrombosis, CPEC offers advantages over conventional approaches, including the elimination of the need for anti-clogging drugs, which pave the way for improved therapeutic outcomes and management of atherosclerosis-related medical procedures.

Recent advance in treatment of atherosclerosis: Key targets and plaque-positioned delivery strategies

Atherosclerosis, a chronic inflammatory disease of vascular wall, is a progressive pathophysiological process with lipids oxidation/depositing initiation and innate/adaptive immune responses. The coordination of multi systems covering oxidative stress, dysfunctional endothelium, diseased lipid uptake, cell apoptosis, thrombotic and pro-inflammatory responding as well as switched SMCs contributes to plaque growth. In this circumstance, inevitably, targeting these processes is considered to be effective for treating atherosclerosis. Arriving, retention and working of payload candidates mediated by targets in lesion direct ultimate therapeutic outcomes. Accumulating a series of scientific studies and clinical practice in the past decades, lesion homing delivery strategies including stent/balloon/nanoparticle-based transportation worked as the potent promotor to ensure a therapeutic effect. The objective of this review is to achieve a very brief summary about the effective therapeutic methods cooperating specifical targets and positioning-delivery strategies in atherosclerosis for better outcomes.

Adult Human Vascular Smooth Muscle Cells on 3D Silk Fibroin Nonwovens Release Exosomes Enriched in Angiogenic and Growth-Promoting Factors

BACKGROUND

Our earlier works showed the quick vascularization of mouse skin grafted Bombyx mori 3D silk fibroin nonwoven scaffolds (3D-SFnws) and the release of exosomes enriched in angiogenic/growth factors (AGFs) from in vitro 3D-SFnws-stuck human dermal fibroblasts (HDFs). Here, we explored whether coronary artery adult human smooth muscle cells (AHSMCs) also release AGFs-enriched exosomes when cultured on 3D-SFnws in vitro.

METHODS

Media with exosome-depleted FBS served for AHSMCs and human endothelial cells (HECs) cultures on 3D-SFnws or polystyrene. Biochemical methods and double-antibody arrays assessed cell growth, metabolism, and intracellular TGF-β and NF-κB signalling pathways activation. AGFs conveyed by CD9+/CD81+ exosomes released from AHSMCs were double-antibody array analysed and their angiogenic power evaluated on HECs in vitro.

RESULTS

AHSMCs grew and consumed D-glucose more intensely and showed a stronger phosphorylation/activation of TAK-1, SMAD-1/-2/-4/-5, ATF-2, c-JUN, ATM, CREB, and an IκBα phosphorylation/inactivation on SFnws vs. polystyrene, consistent overall with a proliferative/secretory phenotype. SFnws-stuck AHSMCs also released exosomes richer in IL-1α/-2/-4/-6/-8; bFGF; GM-CSF; and GRO-α/-β/-γ, which strongly stimulated HECs' growth, migration, and tubes/nodes assembly in vitro.

CONCLUSIONS

Altogether, the intensified AGFs exosomal release from 3D-SFnws-attached AHSMCs and HDFs could advance grafts' colonization, vascularization, and take in vivo-noteworthy assets for prospective clinical applications.

Pentoxifylline Prevents Restenosis by Inhibiting Cell Proliferation via p38MAPK Pathway in Rat Vein Graft Model

Coronary artery bypass grafting remains the gold standard in the therapy of advanced-stage patients. But the vein grafts are prone to restenosis or failure. Pentoxifylline (PTX) is a methylxanthine derivative with a function of inhibiting cell proliferation. We thus applied PTX locally to the vein grafts to study its effect on the inhibition of graft restenosis using a rat vein graft model. Morphometric results showed a significant decrease in the thickness of vein grafts intimal and medial at day 28 after the bypass operation. Results from Western blot and immunohistochemistry showed that PTX also significantly reduced the proliferating cell nuclear antigen (PCNA), alpha-smooth muscle actin (α-SMA) expression, and phosphorylation of p38 in vein grafts. These results firstly discovered the positive role of PTX in preventing the vein grafts restenosis and the mechanism may be inhibition of vascular smooth muscle cells (VSMCs) proliferation via the p38MAPK pathway.

Extracellular Vesicles Mediate Communication between Endothelial and Vascular Smooth Muscle Cells

The recruitment of pericytes and vascular smooth muscle cells (SMCs) that enwrap endothelial cells (ECs) is a crucial process for vascular maturation and stabilization. Communication between these two cell types is crucial during vascular development and in maintaining vessel homeostasis. Extracellular vesicles (EVs) have emerged as a new communication tool involving the exchange of microRNAs between cells. In the present study, we searched for microRNAs that could be transferred via EVs from ECs to SMCs and vice versa. Thanks to a microRNA profiling experiment, we found that two microRNAs are more exported in each cell type in coculture experiments: while miR-539 is more secreted by ECs, miR-582 is more present in EVs from SMCs. Functional assays revealed that both microRNAs can modulate both cell-type phenotypes. We further identified miR-539 and miR-582 targets, in agreement with their respective cell functions. The results obtained in vivo in the neovascularization model suggest that miR-539 and miR-582 might cooperate to trigger the process of blood vessel coverage by smooth muscle cells in a mature plexus. Taken together, these results are the first to highlight the role of miR-539 and miR-582 in angiogenesis and communication between ECs and SMCs.

A Adiponectina Previne a Reestenose pela Inibição da Proliferação Celular em um Modelo de Enxerto Venoso em Ratos

Fundamento:

O enxerto de bypass na artéria coronária (CABG) continua a ser eficiente como tratamento para pacientes portadores de doença arterial coronariana; entretanto, o enxerto venoso tende a apresentar reestenose ou oclusão. A adiponectina (ADP) é uma proteína hormonal plasmática com a função de regular a proliferação celular.

Objetivo:

Foram utilizadas duas doses diferentes da proteína ADP em um modelo de enxerto venoso em ratos para estimular a alteração do enxerto venoso. O objetivo deste estudo foi investigar o efeito da ADP sobre a reestenose em enxerto venoso.

Métodos:

Veias jugulares autólogas foram implantadas como enxertos interposicionais de carótida pela técnica de anastomose de manga em ratos Sprague Dawley. A adiponectina (2,5 μg e 7,5 μg) foi entregue ao enxerto venoso por bypass de forma perivascular, suspensa em gel Pluronic-F127 a 30%. O grupo tratado apenas com bypass e o grupo tratado com gel veículo carregado apenas com Pluronic funcionaram como controle. Foram feitas comparações com análise de via única de variância e teste post-hoc, com p <0,05 sendo considerado significativo.

Resultados:

A proliferação celular (índice de PCNA) foi significativamente baixa no grupo tratado com adiponectina em comparação com o grupo de controle e o grupo tratado com o gel veículo na íntima e na adventícia dos enxertos a partir do dia 3 (p <0,01). VCAM-1 e ICAM-1 avaliados por imuno-histoquímica diminuíram significativamente em enxertos venosos tratados com adiponectina na quarta semana (p <0,01). O tratamento de enxertos venosos com gel carregado com adiponectina reduziu a espessura da íntima, da média e da adventícia, em comparação com os enxertos de controle e tratados com gel veículo no dia 28 (p <0,01).

Conclusões:

Este estudo oferece evidências adicionais do possível papel terapêutico da adiponectina na modulação de lesão vascular e seu reparo.

Cellular Crosstalk between Endothelial and Smooth Muscle Cells in Vascular Wall Remodeling

Pathological vascular wall remodeling refers to the structural and functional changes of the vessel wall that occur in response to injury that eventually leads to cardiovascular disease (CVD). Vessel wall are composed of two major primary cells types, endothelial cells (EC) and vascular smooth muscle cells (VSMCs). The physiological communications between these two cell types (EC–VSMCs) are crucial in the development of the vasculature and in the homeostasis of mature vessels. Moreover, aberrant EC–VSMCs communication has been associated to the promotor of various disease states including vascular wall remodeling. Paracrine regulations by bioactive molecules, communication via direct contact (junctions) or information transfer via extracellular vesicles or extracellular matrix are main crosstalk mechanisms. Identification of the nature of this EC–VSMCs crosstalk may offer strategies to develop new insights for prevention and treatment of disease that curse with vascular remodeling. Here, we will review the molecular mechanisms underlying the interplay between EC and VSMCs. Additionally, we highlight the potential applicable methodologies of the co-culture systems to identify cellular and molecular mechanisms involved in pathological vascular wall remodeling, opening questions about the future research directions.

High fluid shear stress prevents atherosclerotic plaque formation by promoting endothelium denudation and synthetic phenotype of vascular smooth muscle cells

Low blood fluid shear stress (SS) promotes vascular remodeling and atherosclerosis; however, the effects of high (H)SS on vascular remodeling and atherogenesis is not fully clarified. The major goal of this study was to investigate the role of HSS in atherosclerotic plaque formation. A perivascular SS modifier was implanted in the right carotid artery of apolipoprotein E (ApoE)^−/− mice to induce HSS, whereas the left carotid artery represented undisturbed (U)SS as a control in vivo. In vitro modeling used human umbilical vein endothelial cells and vascular smooth muscle cells exposed to HSS (2.5 Pa) using a parallel-plate flow system. The results demonstrated that there were no plaque formations or endothelial cells in the HSS regions of the carotid artery in ApoE^−/− mice. The number of umbilical vein endothelial cells was markedly decreased in a time-dependent manner in HSS. HSS significantly decreased α-smooth muscle actin and increased osteopontin protein expression levels compared with USS in vascular smooth muscle cells (P<0.05). In addition, HSS significantly increased the protein expression levels of collagen α1(XVIII) chain/endostatin and matrix metalloproteinase-8 in vascular smooth muscle cells. These data indicated that HSS may prevent atherosclerotic plaque formation through endothelium denudation and contractile-to-synthetic phenotypic conversion of smooth muscle cells.

Loss of Transforming Growth Factor Beta Signaling in Aortic Smooth Muscle Cells Causes Endothelial Dysfunction and Aortic Hypercontractility

[Figure: see text].

The Effect of the Controlled Release of Platelet Lysate from PVA Nanomats on Keratinocytes, Endothelial Cells and Fibroblasts

Platelet lysate (PL) provides a natural source of growth factors and other bioactive molecules, and the local controlled release of these bioactive PL components is capable of improving the healing of chronic wounds. Therefore, we prepared composite nanofibrous meshes via the needleless electrospinning technique using poly(vinyl alcohol) (PVA) with a high molecular weight and with a high degree of hydrolysis with the incorporated PL (10% w/w). The morphology, wettability and protein release from the nanofibers was then assessed from the resulting composite PVA–PL nanomats. The bioactivity of the PVA–PL nanomats was proved in vitro using HaCaT keratinocytes, human saphenous endothelial cells (HSVECs) and 3T3 fibroblasts. The PVA–PL supported cell adhesion, proliferation, and viability. The improved phenotypic maturation of the HaCaT cells due to the PVA–PL was manifested via the formation of intermediate filaments positive for cytokeratin 10. The PVA–PL enhanced both the synthesis of the von Willebrand factor via HSVECs and HSVECs chemotaxis through membranes with 8 µm-sized pores. These results indicated the favorable effects of the PVA–PL nanomats on the three cell types involved in the wound healing process, and established PVA–PL nanomats as a promising candidate for further evaluation with respect to in vivo experiments.

Mueller polarimetric imaging for fast macroscopic mapping of microscopic collagen matrix remodeling by smooth muscle cells

Smooth muscle cells (SMCs) are critical players in cardiovascular disease development and undergo complex phenotype switching during disease progression. However, SMC phenotype is difficult to assess and track in co-culture studies. To determine the contractility of SMCs embedded within collagen hydrogels, we performed polarized light imaging and subsequent analysis based on Mueller matrices. Measurements were made both in the absence and presence of endothelial cells (ECs) in order to establish the impact of EC-SMC communication on SMC contractility. The results demonstrated that Mueller polarimetric imaging is indeed an appropriate tool for assessing SMC activity which significantly modifies the hydrogel retardance in the presence of ECs. These findings are consistent with the idea that EC-SMC communication promotes a more contractile SMC phenotype. More broadly, our findings suggest that Mueller polarimetry can be a useful tool for studies of spatial heterogeneities in hydrogel remodeling by SMCs.

Downregulation of lncRNA MIR181A2HG by high glucose impairs vascular endothelial cell proliferation and migration through the dysregulation of the miRNAs/AKT2 axis

Endothelial dysfunction and diabetic vascular disease induced by chronic hyperglycemia involve complex interactions among high glucose, long non-coding RNAs (lncRNAs), microRNAs (miRNAs or miRs) and the Ser/Thr kinase AKT. However, the molecular mechanisms under-lying the regulatory crosstalk between these have not yet been completely elucidated. Thus, the present study aimed to explore the molecular mechanisms whereby high glucose (HG)-induced lncRNA MIR181A2HG modulates human umbilical vein endothelial cell (HUVEC) proliferation and migration by regulating AKT2 expression. The persistent exposure of HUVECs to HG resulted in MIR181A2HG down-regulation and thus reduced its ability to sponge miR-6832-5p, miR-6842-5p and miR-8056, subsequently leading to an increase in miR-6832-5p, miR-6842-5p and miR-8056 levels. Mechanistically, miR-6832-5p, miR-6842-5p and miR-8056 were found to target the 3′UTR of AKT2 mRNA in HUVECs, and the increase in their levels led to a decreased expression of AKT2. Thus, this also led to the suppression of HUVEC proliferation and migration, and the formation of capillary-like structures. Moreover, the suppression of HUVEC proliferation and migration induced by MIR181A2HG downregulation was accompanied by changes in glucose metabolism. On the whole, the present study demonstrates that the downregulation of lncRNA MIR181A2HG by HG impairs HUVEC proliferation and migration by dysregulating the miRNA/AKT2 axis. The MIR181A2HG/miRNA/AKT2 regulatory axis may thus be a potential therapeutic target for HG-induced endothelial dysfunction.

PERK Inhibition Promotes Post-angioplasty Re-endothelialization via Modulating SMC Phenotype Changes

BACKGROUND

Drug-eluting stents impair post-angioplasty re-endothelialization thus compromising restenosis prevention while heightening thrombotic risks. We recently found that inhibition of protein kinase RNA-like endoplasmic reticulum kinase (PERK) effectively mitigated both restenosis and thrombosis in rodent models. This motivated us to determine how PERK inhibition impacts re-endothelialization.

METHODS

Re-endothelialization was evaluated in endothelial-denuded rat carotid arteries after balloon angioplasty and periadventitial administration of PERK inhibitor in a hydrogel. To study whether PERK in smooth muscle cells (SMCs) regulates re-endothelialization by paracrinally influencing endothelial cells (ECs), denuded arteries exposing SMCs were lentiviral-infected to silence PERK; in vitro, the extracellular vesicles isolated from the medium of PDGF-activated, PERK-upregulating human primary SMCs were transferred to human primary ECs.

RESULTS

Treatment with PERK inhibitor versus vehicle control accelerated re-endothelialization in denuded arteries. PERK-specific silencing in the denuded arterial wall (mainly SMCs) also enhanced re-endothelialization compared to scrambled shRNA control. In vitro, while medium transfer from PDGF-activated SMCs impaired EC viability and increased the mRNA levels of dysfunctional EC markers, either PERK inhibition or silencing in donor SMCs mitigated these EC changes. Furthermore, CXCL10, a paracrine cytokine detrimental to ECs, was increased by PDGF activation and decreased after PERK inhibition or silencing in SMCs.

CONCLUSIONS

Attenuating PERK activity pharmacologically or genetically provides an approach to accelerating post-angioplasty re-endothelialization in rats. The mechanism may involve paracrine factors regulated by PERK in SMCs that impact neighboring ECs. This study rationalizes future development of PERK-targeted endothelium-friendly vascular interventions.

LncRNA GAS5 attenuates fibroblast activation through inhibiting Smad3 signaling

Transforming growth factor-β (TGF-β)-induced fibroblast activation is a key pathological event during tissue fibrosis. Long noncoding RNA (lncRNA) is a class of versatile gene regulators participating in various cellular and molecular processes. However, the function of lncRNA in fibroblast activation is still poorly understood. In this study, we identified growth arrest-specific transcript 5 (GAS5) as a novel regulator for TGF-β-induced fibroblast activation. GAS5 expression was downregulated in cultured fibroblasts by TGF-β and in resident fibroblasts from bleomycin-treated skin tissues. Overexpression of GAS5 suppressed TGF-β-induced fibroblast to myofibroblast differentiation. Mechanistically, GAS5 directly bound mothers against decapentaplegic homolog 3 (Smad3) and promoted Smad3 binding to Protein phosphatase 1A (PPM1A), a Smad3 dephosphatase, and thus accelerated Smad3 dephosphorylation in TGF-β-treated fibroblasts. In addition, GAS5 inhibited fibroblast proliferation. Importantly, local delivery of GAS5 via adenoviral vector suppressed bleomycin-induced skin fibrosis in mice. Collectively, our data revealed that GAS5 suppresses fibroblast activation and fibrogenesis through inhibiting TGF-β/Smad3 signaling, which provides a rationale for an lncRNA-based therapy to treat fibrotic diseases.

Adventitial fibroblast-derived vascular endothelial growth factor promotes vasa vasorum-associated neointima formation and macrophage recruitment

Aims

Adventitial vasa vasorum provides oxygen and nourishment to the vascular wall, but whether it regulates vascular disease remains unclear. We have previously shown that an increased expression of VEGF (vascular endothelial growth factor) is associated with macrophage infiltration. This study aims to determine whether adventitial fibroblast (AF)-derived VEGF increases the number of vasa vasorum contributing to neointima formation through macrophage recruitment.

Methods and results

In rat balloon injury model, vasa vasorum count was increased particularly in the adventitia accompanied by cell proliferation and VEGF expression. Both endogenous and PKH26-labelled exogenous macrophages were mainly distributed in adventitia around vasa vasorum. Interestingly, perivascular delivery of Ranibizumab preferentially concentrated in adventitia resulted in a decrease of neointima formation with concurrent reduction of vasa vasorum count and macrophage infiltration. AFs with adenovirus-mediated VEGF over-expression delivered to the adventitia significantly enhanced these pathological changes after injury. In Tie2-cre/Rosa-LoxP-RFP mice, endothelial cells were increased in the adventitia after wire injury. By using multiphoton laser scanning microscopy, macrophage rolling, adhesion and transmigration were observed in vasa vasorum. Moreover, adoptive transfer of macrophages accelerated injury-induced neointima formation. VEGF-neutralizing antibody administration also attenuated wire injury-induced neointima formation and macrophage infiltration. In primary cultured AFs, exogenous VEGF increased VEGF expression and secretion in a time- and dose-dependent manner. AF-conditioned medium promoted endothelial cell angiogenesis, vascular cell adhesion molecule-1 expression and macrophage adhesion was blocked by VEGF-neutralizing antibody and VEGFR2 inhibitor ZM323881, which also inhibited activation of VEGFR2/ERK1/2 pathway.

Conclusion

These results demonstrate that AF-derived VEGF plays a significant role in the increase of vasa vasorum count which is involved in macrophage recruitment and neointima formation.

LncRNA GAS5 regulates vascular smooth muscle cell cycle arrest and apoptosis via p53 pathway

Vascular remodeling is a pathological process following cardiovascular intervention. Vascular smooth muscle cells (VSMC) play a critical role in the vascular remodeling. Long noncoding RNAs (lncRNA) are a class of gene regulators functioning through various mechanisms in physiological and pathological conditions. By using cultured VSMC and rat carotid artery balloon injury model, we found that lncRNA growth arrest specific 5 (GAS5) serves as a negative regulator for VSMC survival in vascular remodeling. By manipulating GAS5 expression via adenoviral overexpression or short hairpin RNA knockdown, we found that GAS5 suppresses VSMC proliferation while promoting cell cycle arrest and inducing cell apoptosis. Mechanistically, GAS5 directly binds to p53 and p300, stabilizes p53-p300 interaction, and thus regulates VSMC cell survival via induction of p53-downstream target genes. Importantly, local delivery of GAS5 via adenoviral vector suppresses balloon injury-induced neointima formation along with an increased expression of p53 and apoptosis in neointimal SMCs. Our study demonstrated for the first time that GAS5 negatively impacts VSMC survival via activation the p53 pathway during vascular remodeling.

The phenotype of vascular smooth muscle cells co-cultured with endothelial cells is modulated by PDGFR-β/IQGAP1 signaling in LPS-induced intravascular injury

Background Sepsis, a leading cause of death in intensive care units, is generally associated with vascular dysfunction. However, its pathophysiological process has not been fully clarified, lacking in-depth knowledge of its pathophysiological process may hinder the improvement of diagnosis and therapy for sepsis. Hence, as the key parts of the vascular wall, the interaction between endothelial cells (ECs) and smooth muscle cells (SMCs) under septic situation need to be further studied. Methods ECs and SMCs were co-cultured using Transwell plates. Lipopolysaccharide (LPS) was used to induce sepsis. A scratch-wound assay was used to assess cell migration, and western blotting was used to assess the level of redifferentiation of SMCs as well as the expression of PDGFR-β and IQGAP1. Results Co-culture with ECs reduced the redifferentiation of SMCs induced by LPS (10 μg/ml), which was characterized by increased migration ability and decreased expression of contractile proteins (e.g., SM22 and α-SMA). The production of TNF-α could decrease the level of PDGFR-β in SMCs. Treatment of SMCs with the PDGFR-β inhibitor imatinib (5 μM) was able to counteract LPS-induced SMC redifferentiation and reduce IQGAP1 protein expression, especially when SMCs were co-cultured with ECs. Conclusion The phenotype of vascular SMCs co-cultured with ECs was modulated by IQGAP1 through the PDGFR-β pathway, which may lead to vascular remodeling and homeostasis in LPS-induced intravascular injury. This pathway could be a novel target for the treatment of vascular damage.