Neural stem cell-derived exosomes regulate cell proliferation,migration,and cell death of brain microvascular endothelial cells via the miR-9/Hes1 axis under hypoxia

Background:Our previous study found that mouse embryonic neural stem cell(NSC)-derived exosomes(EXOs)regulated NSC differentiation via the miR-9/Hes1 axis.However,the effects of EXOs on brain microvascular endothelial cell(BMEC)dysfunction via the miR-9/Hes1 axis remain unknown.Therefore,the current study aimed to determine the effects of EXOs on BMEC proliferation,migration,and death via the miR-9/Hes1 axis.Methods:Immunofluorescence,quantitative real-time polymerase chain reaction,cell counting kit-8 assay,wound healing assay,calcein-acetoxymethyl/propidium iodide staining,and hematoxylin and eosin staining were used to determine the role and mechanism of EXOs on BMECs.Results:EXOs promoted BMEC proliferation and migration and reduced cell death under hypoxic conditions.The overexpression of miR-9 promoted BMEC prolifera-tion and migration and reduced cell death under hypoxic conditions.Moreover,miR-9 downregulation inhibited BMEC proliferation and migration and also promoted cell death.Hes1 silencing ameliorated the effect of amtagomiR-9 on BMEC proliferation and migration and cell death.Hyperemic structures were observed in the regions of the hippocampus and cortex in hypoxia-induced mice.Meanwhile,EXO treatment improved cerebrovascular alterations.Conclusion:NSC-derived EXOs can promote BMEC proliferation and migra-tion and reduce cell death via the miR-9/Hes1 axis under hypoxic conditions.Therefore,EXO therapeutic strategies could be considered for hypoxia-induced vascular injury.

Exploring the mechanism of icariin in regulat⁃ing cardiac microvascular endothelial cells based on network pharmacology,molecular docking and in vitro experiments

OBJECTIVE To investigate the regulatory effects of icariin(ICA)on cardiac micro⁃vascular endothelial cells(CMEC)after oxygenglucose deprivation reperfusion(OGD/R)injury.METHODS CMEC were subjected to OGD/R treatment to construct a myocardial ischemiareperfusion model,and were divided into normal,model,low(10μmol·L^(-1)),medium(20μmol·L^(-1))and high(40μmol·L^(-1))ICA group,and high ICA+inhibitor group(40μmol·L^(-1)+20 nmol·L^(-1)).CCK-8 assay was used to assess the protective ability of ICA against CMEC,and cell migration assay and tube-formation assay were used to detect the migration and generation ability of CMEC.The TCMSP database,Swiss-Target database and literature mining methods were used to col⁃lect ICA-related targets,the GeneCards data⁃base was used to collect target genes related to myocardial ischemia/reperfusion,and Cytoscape 3.8.0 software was used to construct a"drug-tar⁃get-disease"network.The potential targets were imported into STRING 11.5 database to obtain the PPI network.GO and KEGG enrichment analyses were performed on the potential targets using the DAVID database.Molecular docking was performed using AutoDock-vina 1.1.2 soft⁃ware.Western blot detected the expression of related proteins.RESULTS After CMEC was subjected to OGD/R treatment,ICA had a protec⁃tive effect at 10^(-1)60μmol·L^(-1);the results of the cell migration assay showed that each group of ICA could promote the migratory effect of CMEC(P<0.01,P<0.01);and the results of tube-for⁃mation assay showed that each group of ICA could significantly promote the generation of branches(P<0.01)and the capillary length exten⁃sion(P<0.05).Network pharmacology collected a total of 23 ICA action targets,1500 disease tar⁃gets and 12 key targets.GO function enrichment analysis found 85 results.KEGG pathway enrich⁃ment analysis found 53 results,involving AGERAGE signaling pathway,sphingolipid signaling pathway and VEGF signaling pathway.Molecu⁃lar docking results showed that ICA had better binding with core targets PRKCB,PRKCA and PTGS2.Western blot results showed that ICA could regulate the expression of PRKCB,PRKCA and PTGS2 proteins.The results of cell migra⁃tion assay,tube-formation assay and protein expression were reversed after addition of PKC inhibitor.CONCLUSION The potential mecha⁃nism of action of ICA against myocardial isch⁃emia-reperfusion injury may be related to the reg⁃ulation of processes such as CMEC migration and angiogenesis,and it functions through the key target gene PKC.

Down-regulation of histone deacetylase 7 reduces biological activities of retinal microvascular endothelial cells under high glucose condition and related mechanism

AIM:To investigate the expression and effect of histone deacetylase 7(HDAC7)in human retinal microvascular endothelial cells(HRMECs)under high glucose condition and related mechanism,and the expression of HDAC7 in the retinal tissue in diabetic rats.METHODS:The expression of HDAC7 in HRMECs under high glucose and the retinal tissue from normal or diabetic rats were detected with immunohistochemistry and Western blot.LV-shHDAC7 HRMECs were used to study the effect of HDAC7 on cell activities.Cell count kit-8(CCK-8),5-ethynyl2’-deoxyuridine(EdU),flow cytometry,scratch test,Transwell test and tube formation assay were used to examine the ability of cell proliferation,migration,and angiogenesis.Finally,a preliminary exploration of its mechanism was performed by Western blot.RESULTS:The expression of HDAC7 was both upregulated in retinal tissues of diabetic rats and high glucosetreated HRMECs.Down-regulation of HDAC7 expression significantly reduced the ability of proliferation,migration,and tube formation,and reversed the high glucose-induced high expression of CDK1/Cyclin B1 and vascular endothelial growth factor in high glucose-treated HRMECs.CONCLUSION:High glucose can up-regulate the expression of HDAC7 in HRMECs.Down-regulation of HDAC7 can inhibit HRMECs activities.HDAC7 is proposed to be involved in pathogenesis of diabetic retinopathy and a therapeutic target.

Alleviation of acute pancreatitis-associated lung injury by inhibiting the p38 mitogen-activated protein kinase pathway in pulmonary microvascular endothelial cells

BACKGROUND Previous reports have suggested that the p38 mitogen-activated protein kinase signaling pathway is involved in the development of severe acute pancreatitis(SAP)-related acute lung injury(ALI).Inhibition of p38 by SB203580 blocked the inflammatory responses in SAP-ALI.However,the precise mechanism associated with p38 is unclear,particularly in pulmonary microvascular endothelial cell(PMVEC)injury.AIM To determine its role in the tumor necrosis factor-alpha(TNF-α)-induced inflammation and apoptosis of PMVECs in vitro.We then conducted in vivo experiments to confirm the effect of SB203580-mediated p38 inhibition on SAP-ALI.METHODS In vitro,PMVEC were transfected with mitogen-activated protein kinase kinase 6(Glu),which constitutively activates p38,and then stimulated with TNF-α.Flow cytometry and western blotting were performed to detect the cell apoptosis and inflammatory cytokine levels,respectively.In vivo,SAP-ALI was induced by 5%sodium taurocholate and three different doses of SB203580(2.5,5.0 or 10.0 mg/kg)were intraperitoneally injected prior to SAP induction.SAP-ALI was assessed by performing pulmonary histopathology assays,measuring myeloperoxidase activity,conducting arterial blood gas analyses and measuring TNF-α,interleukin(IL)-1βand IL-6 levels.Lung microvascular permeability was measured by determining bronchoalveolar lavage fluid protein concentration,Evans blue pulmonary cells was confirmed by performing a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling analysis and examining the Bcl2,Bax,Bim and cle-caspase3 levels.The proteins levels of P-p38,NFκB,IκB,P-signal transducer and activator of transcription-3,nuclear factor erythroid 2-related factor 2,HO-1 and Myd88 were detected in the lungs to further evaluate the potential mechanism underlying the protective effect of SB203580.RESULTS In vitro,mitogen-activated protein kinase(Glu)transfection resulted in higher apoptotic rates and cytokine(IL-1βand IL-6)levels in TNF-α-treated PMVECs.In vivo,SB2035080 attenuated lung histopathological injury,decreased inflammatory activity(TNF-α,IL-1β,IL-6 and myeloperoxidase)and preserved pulmonary function.Furthermore,SB203580 significantly reversed changes in the bronchoalveolar lavage fluid protein concentration,Evans blue accumulation,terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cell numbers,apoptosis-related proteins(cle-caspase3,Bim and Bax)and endothelial microstructure.Moreover,SB203580 significantly reduced the pulmonary P-p38,NFκB,P-signal transducer and activator of transcription-3 and Myd88 levels but increased the IκB and HO-1 levels.CONCLUSION p38 inhibition may protect against SAP-ALI by alleviating inflammation and the apoptotic death of PMVECs.

Repression of retinal microvascular endothelial cells by transthyretin under simulated diabetic retinopathy conditions

AIM: To investigate biological effects of transthyretin(TTR) on the development of neovascularization under simulated diabetic retinopathy(DR) condition associated with high glucose and hypoxia. METHODS: Human retinal microvascular endothelial cells(h RECs) were cultured in normal and simulated DR environments with high glucose and hypoxia. The normal serum glucose concentration is approximately 5.5 mmol/L;thus, hyperglycemia was simulated with 25 mmol/L glucose, while hypoxia was induced using 200 μmol/L Co Cl2. The influence of TTR on h RECs and human retinal pigment epithelial cells(h RPECs) was determined by incubating the cells with 4 μmol/L TTR in normal and abnormal media. A co-culture system was then employed to evaluate the effects of h RPECs on h RECs. RESULTS: Decreased h RECs and h RPECs were observed under abnormal conditions, including high-glucose and hypoxic media. In addition, h RECs were significantly inhibited by 4 μmol/L exogenous TTR during hyperglycemic culture. During co-culture, h RPECs inhibited h RECs in both the normal and abnormal environments.CONCLUSION: h REC growth is inhibited by exogenous TTR under simulated DR environments with high-glucose and hypoxic, particularly in the medium containing 25 mmol/L glucose. h RPECs, which manufacture TTR in the eye, also represses h RECs in the same environment. TTR is predicted to inhibit the proliferation of h RECs and neovascularization.

Inhibitory effects of safranal on laser-induced choroidal neovascularization and human choroidal microvascular endothelial cells and related pathways analyzed with transcriptome sequencing

AIM:To determine the effects of safranal on choroidal neovascularization(CNV)and oxidative stress damage of human choroidal microvascular endothelial cells(HCVECs)and its possible mechanisms.METHODS:Forty-five rats were used as a laser-induced CNV model for testing the efficacy and safety of safranal(0.5 mg/kg·d,intraperitoneally)on CNV.CNV leakage on fluorescein angiography(FA)and CNV thickness on histology was compared.HCVECs were used for a H_(2)O_(2)-induced oxidative stress model to test the effect of safranal in vitro.MTT essay was carried to test the inhibition rate of safranal on cell viability at different concentrations.Tube formation was used to test protective effect of safranal on angiogenesis at different concentrations.mRNA transcriptome sequencing was performed to find the possible signal pathway.The expressions of different molecules and their phosphorylation level were validated by Western blotting.RESULTS:On FA,the average CNV leakage area was 0.73±0.49 and 0.31±0.11 mm^(2)(P=0.012)in the control and safranal-treated group respectively.The average CNV thickness was 127.4±18.75 and 100.6±17.34μm(P=0.001)in control and safranal-treated group.Under the condition of oxidative stress,cell proliferation was inhibited by safranal and inhibition rates were 7.4%-35.4%at the different concentrations.For tube formation study,the number of new branches was 364 in control group and 35,42,and 17 in 20,40,and 80μg/mL safranal groups respectively(P<0.01).From the KEGG pathway bubble graph,the PI3K-AKT signaling pathway showed a high gene ratio.The protein expression was elevated of insulin receptor substrate(IRS)and the phosphorylation level of PI3K,phosphoinositide-dependent protein kinase 1/2(PDK1/2),AKT and Bcl-2 associated death promoter(BAD)was also elevated under oxidative stress condition but inhibited by safranal.CONCLUSION:Safranal can inhibit CNV both in vivo and in vitro,and the IRS-PI3K-PDK1/2-AKT-BAD signaling pathway is involved in the pathogenesis of CNV.

Primary culture and identification about brain microvascular endothelial cells of rabbits

Objective:To establish a simple and efficient culture method of primary rabbit brain microvascular endothelial cells,provide important carriers and tool cells for the research of related cerebrovascular diseases.Methods:The cerebral cortexes of rabbits were collected aseptic and inoculated after cutting,passing through cell sieve,bovine serum albumin density gradient centrifugation,typeⅡcollagenase digestion,finally inoculated and cultured.The cultured cells were identified by cell morphological observation and angiogenesis experiment.Results:Under the inverted microscope,the cells were short fusiform or polygonal,and grew in clusters and adhere to the wall.After the cells were densely fused,they would be in a typical monolayer flat,“pebbled"mosaic arrangement.Tube formation test had the ability to form tubes structure.Conclusion:This method can successfully separate and cultivate primary rabbit brain microvascular endothelial cells.

Simple, Reliable Isolation, Purification and Cultivation of Murine Skeletal Muscle Microvascular Endothelial Cells

Objectives: Microvascular dysfunction in skeletal muscle is involved in metabolic and vascular diseases. Microvascular endothelial cells (MEC) are poorly characterized in the progression of associated diseases in part due to lack of availability of MEC from various animal models. The objective was to provide a fast, simple, and efficient method to isolate murine MEC derived from skeletal muscle. Methods: Dissected abdominal skeletal muscles from C57BL/6J mice at 8 - 12 weeks of age were enzymatically dissociated. MEC were isolated using a modified two-step Dynabeads™-based purification method. With a combination of Dynabeads™ - Griffonia simplicifolia lectin-I and Dynabeads™ - monoclonal antibody against CD31/PECAM-1, MEC were isolated and purified twice followed by cultivation. Results: Isolated and purified cells were viable and cultured. MEC were characterized by using immunofluorescence to identify CD31/PECAM-1, an EC marker, and two specific functional assays, which include a capillary-like tube formation and the uptake of Dil-Ac-LDL. The purity of isolated cell populations from skeletal muscle microvessels, which was assessed by flow cytometry, was 88.02% ± 2.99% (n = 6). Conclusions: This method is simple, fast, and highly reproducible for isolating MEC from murine skeletal muscle. The method will enable us to obtain primary cultured MEC from various genetic or diseased murine models, contributing to insightful knowledge of diseases associated with the dysfunction of microvessels.

Claudin-1 Leads to Strong Formation of Tight Junction in Cultured Mouse Lung Microvascular Endothelial Cells

We aimed to examine paracellular barrier function in cultured mouse lung microvascular endothelial cells (LMECs). The transcellular resistance of LMEC monolayers yielded an electrical resistance of approximately 19 Ω × cm2 at days 6 - 7 in culture when the cells reached confluence, and paracellular permeable clearance of sodium fluorescein was the lowest on day 6 in culture, suggesting the formation of tight junctions (TJs) in cultured LMECs. Moreover, the expression of TJ-associated proteins, occludin, claudin-1 and -4 and zonula occludents 1 (ZO-1) was detected in LMECs at day 6 in culture. However, mRNAs of occludin, claudin-1 and -4 and ZO-1 were already expressed on day 1 after culture, and large variations were absent in the mRNA levels of occludin, claudin-4 and ZO-1 between days 1 and 7 in culture, when the level of each mRNA on day 1 in culture was used as a basal level. However, the claudin-1 mRNA level gradually increased up to approximately 7-fold on day 7 in culture over the basal level. These results indicate that the drastic increase in the mRNA expression level of claudin-1 leads to the strong formation of TJs.

Microvascular endothelial cells derived from spinal cord promote spinal cord injury repair

Neural regeneration after spinal cord injury (SCI) closely relates to the microvascular endothelial cell (MEC)- mediated neurovascular unit formation. However, the effects of central nerve system-derived MECs on neovascularization and neurogenesis, and potential signaling involved therein, are unclear. Here, we established a primary spinal cord-derived MECs (SCMECs) isolation with high cell yield and purity to describe the differences with brain-derived MECs (BMECs) and their therapeutic effects on SCI. Transcriptomics and proteomics revealed differentially expressed genes and proteins in SCMECs were involved in angiogenesis, immunity, metabolism, and cell adhesion molecular signaling was the only signaling pathway enriched of top 10 in differentially expressed genes and proteins KEGG analysis. SCMECs and BMECs could be induced angiogenesis by different stiffness stimulation of PEG hydrogels with elastic modulus 50-1650 Pa for SCMECs and 50-300 Pa for BMECs, respectively. Moreover, SCMECs and BMECs promoted spinal cord or brain-derived NSC (SNSC/BNSC) proliferation, migration, and differentiation at different levels. At certain dose, SCMECs in combination with the NeuroRegen scaffold, showed higher effectiveness in the promotion of vascular reconstruction. The potential underlying mechanism of this phenomenon may through VEGF/AKT/eNOS- signaling pathway, and consequently accelerated neuronal regeneration and functional recovery of SCI rats compared to BMECs. Our findings suggested a promising role of SCMECs in restoring vascularization and neural regeneration.

β-Estradiol 17-acetate enhances the in vitro vitality of endothelial cells isolated from the brain of patients subjected to neurosurgery

In the current landscape of endothelial cell isolation for building in vitro models of the blood-brain barrier,our work moves towards reproducing the features of the neurovascular unit to achieve glial compliance through an innovative biomimetic coating technology for brain chronic implants.We hypothesized that the autologous origin of human brain mic rovascular endothelial cells(hBMECs)is the first requirement for the suitable coating to prevent the glial inflammato ry response trigge red by foreign neuroprosthetics.Therefo re,this study established a new procedure to preserve the in vitro viability of hBMECs isolated from gray and white matter specimens taken from neurosurge ry patients.Culturing adult hBMECs is generally considered a challenging task due to the difficult survival ex vivo and progressive reduction in proliferation of these cells.The addition of 10 nMβ-estradiol 17-acetate to the hBMEC culture medium was found to be an essential and discriminating factor promoting adhesion and proliferation both after isolation and thawing,suppo rting the well-known protective role played by estrogens on microvessels.In particular,β-estradiol 17-acetate was critical for both freshly isolated and thawed female-derived hBMECs,while it was not necessary for freshly isolated male-derived hBMECs;however,it did countera ct the decay in the viability of the latter after thawing.The tumo r-free hBMECs were thus cultured for up to 2 months and their growth efficiency was assessed befo re and after two periods of cryopreservation.Des pite the thermal stress,the hBMECs remained viable and suitable for re-freezing and storage for several months.This approach increasing in vitro viability of hBMECs opens new perspectives for the use of cryopreserved autologous hBMECs as biomimetic therapeutic tools,offering the potential to avoid additional surgical sampling for each patient.

Protective Effect of Naoxintong Capsule(脑心通胶嚢)Combined with Guhong Injection(谷红注射液)on Rat Brain Microvascular Endothelial Cells during Cerebral Ischemia-Reperfusion Injury

Objective:To investigate the synergistic effect of Naoxintong Capsule(NXTC,脑心通胶囊)and Guhong Injection(GHI,谷红注射液)on cerebral ischemia-reperfusion(丨/R)injury.Methods:Forty-eight Sprague-Dawley rats were divided into 6 groups:control group,oxygen and glucose deprivation(OGD)group,nimodipine group(9.375 mg/kg),NXTC group(0.5 g/kg),GHI group(5 mL/kg)and NXTC+GHI group(0.5 g/kg NXTC+5 mL/kg GHI),after the onset of reperfusion and once per day for the following 7 days.Blood was collected 1 h after final administration,and the sera were collected.Cultured primary rat brain microvascular endothelial cells(rBMECs)were subjected to OGD to establish a cell injury model.Untreated rBMECs were used as blank control.The cell counting kit-8 assay was used to assess cell viability using the sera.Malondialdehyde(MDA)and superoxide dismutase(SOD)levels were assessed using an enzyme-linked immunosorbent assay.Apoptosis was evaluated after Hoechst33342 staining using fluorescence microscopy and flow cytometry.JC-1 staining was performed to assess changes in mitochondrial membrane potential.Results:Statistical analysis indicated that more than 95%of the cells were rBMECs.Compared with the OGD group,the cellular morphology of the all drug delivery groups improved.In particular,the combined drug group had the most significant effect.Compared with the OGD group,all drug intervention groups induced a decrease in the apoptotic rate of rBMECs,increased the SOD levels,and decreased the MDA levels(all P<0.01).Compared with the mono-therapy groups,the NXTC+GHI group exhibited a significant improvement in the number of apoptotic rBMECs(P<0.01).All drug intervention groups showed different degrees of increase in membrane potential,and the NXTC+GHI group was higher than the NXTC or GHI group(P<0.01).Conclusion:The combinationa application of NXTC and GHI on cerebral l/R injury clearly resulted in protective benefits.

Integrin binding peptides facilitate growth and interconnected vascular-like network formation of rat primary cortical vascular endothelial cells in vitro

Neovascularization and angiogenesis in the brain are important physiological processes for normal brain development and repair/regeneration following insults. Integrins are cell surface adhesion receptors mediating important function of cells such as survival, growth and development during tissue organization, differentiation and organogenesis. In this study, we used an integrin-binding array platform to identify the important types of integrins and their binding peptides that facilitate adhesion, growth, development, and vascular-like network formation of rat primary brain microvascular endothelial cells. Brain microvascular endothelial cells were isolated from rat brain on post-natal day 7. Cells were cultured in a custom-designed integrin array system containing short synthetic peptides binding to 16 types of integrins commonly expressed on cells in vertebrates. After 7 days of culture, the brain microvascular endothelial cells were processed for immunostaining with markers for endothelial cells including von Willibrand factor and platelet endothelial cell adhesion molecule. 5-Bromo-2′-dexoyuridine was added to the culture at 48 hours prior to fixation to assess cell proliferation. Among 16 integrins tested, we found that α5β1, αvβ5 and αvβ8 greatly promoted proliferation of endothelial cells in culture. To investigate the effect of integrin-binding peptides in promoting neovascularization and angiogenesis, the binding peptides to the above three types of integrins were immobilized to our custom-designed hydrogel in three-dimensional(3 D) culture of brain microvascular endothelial cells with the addition of vascular endothelial growth factor. Following a 7-day 3 D culture, the culture was fixed and processed for double labeling of phalloidin with von Willibrand factor or platelet endothelial cell adhesion molecule and assessed under confocal microscopy. In the 3 D culture in hydrogels conjugated with the integrin-binding peptide, brain microvascular endothelial cells formed interconnected vascular-like network with clearly discernable lumens, which is reminiscent of brain microvascular network in vivo. With the novel integrin-binding array system, we identified the specific types of integrins on brain microvascular endothelial cells that mediate cell adhesion and growth followed by functionalizing a 3 D hydrogel culture system using the binding peptides that specifically bind to the identified integrins, leading to robust growth and lumenized microvascular-like network formation of brain microvascular endothelial cells in 3 D culture. This technology can be used for in vitro and in vivo vascularization of transplants or brain lesions to promote brain tissue regeneration following neurological insults.

Quercetin protects human brain microvascular endothelial cells from fibrillarβ-amyloid_(1–40)-induced toxicity

Amyloid beta-peptides(Aβ) are known to undergo active transport across the blood-brain barrier, and cerebral amyloid angiopathy has been shown to be a prominent feature in the majority of Alzheimer's disease. Quercetin is a natural flavonoid molecule and has been demonstrated to have potent neuroprotective effects, but its protective effect on endothelial cells under Aβ-damaged condition is unclear. In the present study, the protective effects of quercetin on brain microvascular endothelial cells injured by fibrillar Aβ_(1–40)(f Aβ_(1–40)) were observed. The results show that f Aβ_(1–40)-induced cytotoxicity in human brain microvascular endothelial cells(h BMECs) can be relieved by quercetin treatment. Quercetin increases cell viability, reduces the release of lactate dehydrogenase, and relieves nuclear condensation.Quercetin also alleviates intracellular reactive oxygen species generation and increases superoxide dismutase activity. Moreover, it strengthens the barrier integrity through the preservation of the transendothelial electrical resistance value, the relief of aggravated permeability, and the increase of characteristic enzyme levels after being exposed to f Aβ_(1–40). In conclusion, quercetin protects h BMECs from f Aβ_(1–40)-induced toxicity.

Trimethylamine N-oxide aggravates vascular permeability and endothelial cell dysfunction under diabetic condition:in vitro and in vivo study

AIM:To provide the direct evidence for the crucial role of trimethylamine N-oxide(TMAO)in vascular permeability and endothelial cell dysfunction under diabetic condition.METHODS:The role of TMAO on the in vitro biological effect of human retinal microvascular endothelial cells(HRMEC)under high glucose conditions was tested by a cell counting kit,wound healing,a transwell and a tube formation assay.The inflammation-related gene expression affected by TMAO was tested by real-time polymerase chain reaction(RT-PCR).The expression of the cell junction was measured by Western blotting(WB)and immunofluorescence staining.In addition,two groups of rat models,diabetic and non-diabetic,were fed with normal or 0.1%TMAO for 16wk,and their plasma levels of TMAO,vascular endothelial growth factor(VEGF),interleukin(IL)-6 and tumor necrosis factor(TNF)-αwere tested.The vascular permeability of rat retinas was measured using FITC-Dextran,and the expression of zonula occludens(ZO)-1 and claudin-5 in rat retinas was detected by WB or immunofluorescence staining.RESULTS:TMAO administration significantly increased the cell proliferation,migration,and tube formation of primary HRMEC either in normal or high-glucose conditions.RT-PCR showed elevated inflammation-related gene expression of HRMEC under TMAO stimulation,while WB or immunofluorescence staining indicated decreased cell junction ZO-1 and occludin expression after high-glucose and TMAO treatment.Diabetic rats showed higher plasma levels of TMAO as well as retinal vascular leakage,which were even higher in TMAO-feeding diabetic rats.Furthermore,TMAO administration increased the rat plasma levels of VEGF,IL-6 and TNF-αwhile decreasing the retinal expression levels of ZO-1 and claudin-5.CONCLUSION:TMAO enhances the proliferation,migration,and tube formation of HRMEC,as well as destroys their vascular integrity and tight connection.It also regulates the expression of VEGF,IL-6,and TNF-α.

Role of apigenin in high glucose-induced retinal microvascular endothelial cell dysfunction via regulating NOX4/p38 MAPK pathway in vitro

AIM:To investigate the retinoprotective role of Apigenin(Api)against high glucose(HG)-induced human retinal microvascular endothelial cells(HRMECs),and to explore its regulatory mechanism.METHODS:HRMECs were stimulated by HG for 48h to establish the in vitro cell model.Different concentrations of Api(2.5,5,and 10μmol/L)were applied for treatment.Cell counting kit-8(CCK-8),Transwell,and tube formation assays were performed to examine the effects of Api on the viability,migration,and angiogenesis in HG-induced HRMECs.Vascular permeability was evaluated by Evans blue dye.The inflammatory cytokines and oxidative stress-related factors were measured using their commercial kits.Protein expression of nicotinamide adenine dinucleotide phosphate(NADPH)oxidase 4(NOX4)and p38 mitogen-activated protein kinase(MAPK)was measured by Western blot.RESULTS:Api prevented HG-induced HRMECs viability,migration,angiogenesis,and vascular permeability in a concentration-dependent manner.Meanwhile,Api also concentration-dependently inhibited inflammation and oxidative stress in HRMECs exposed to HG.In addition,HG caused an elevated expression of NOX4,which was retarded by Api treatment.HG stimulation facilitated the activation of p38 MAPK signaling in HRMECs,and Api could weaken this activation partly via downregulating NOX4 expression.Furthermore,overexpression of NOX4 or activation of p38 MAPK signaling greatly weakened the protective role of Api against HG-stimulated HRMECs.CONCLUSION:Api might exert a beneficial role in HGstimulated HRMECs through regulating NOX4/p38 MAPK pathway.

Sustained release of vascular endothelial growth factor A and basic fibroblast growth factor from nanofiber membranes reduces oxygen/glucose deprivation-induced injury to neurovascular units

Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway.

A neurovascular unit-on-a-chip:culture and differentiation of human neural stem cells in a three-dimensional microfluidic environment

Biological studies typically rely on a simple monolayer cell culture,which does not reflect the complex functional characteristics of human tissues and organs,or their real response to external stimuli.Microfluidic technology has advantages of high-throughput screening,accurate control of the fluid velocity,low cell consumption,long-term culture,and high integration.By combining the multipotential differentiation of neural stem cells with high throughput and the integrated characteristics of microfluidic technology,an in vitro model of a functionalized neurovascular unit was established using human neural stem cell-derived neurons,astrocytes,oligodendrocytes,and a functional microvascular barrier.The model comprises a multi-layer vertical neural module and vascular module,both of which were connected with a syringe pump.This provides controllable conditions for cell inoculation and nutrient supply,and simultaneously simulates the process of ischemic/hypoxic injury and the process of inflammatory factors in the circulatory system passing through the blood-brain barrier and then acting on the nerve tissue in the brain.The in vitro functionalized neurovascular unit model will be conducive to central nervous system disease research,drug screening,and new drug development.

The relationship among amyloid-βdeposition,sphingomyelin level,and the expression and function of P-glycoprotein in Alzheimer’s disease pathological process

In Alzheimer’s disease,the transporter P-glycoprotein is responsible for the clearance of amyloid-βin the brain.Amyloid-βcorrelates with the sphingomyelin metabolism,and sphingomyelin participates in the regulation of P-glycoprotein.The amyloid cascade hypothesis describes amyloid-βas the central cause of Alzheimer’s disease neuropathology.Better understanding of the change of P-glycoprotein and sphingomyelin along with amyloid-βand their potential association in the pathological process of Alzheimer’s disease is critical.Herein,we found that the expression of P-glycoprotein in APP/PS1 mice tended to increase with age and was significantly higher at 9 and 12 months of age than that in wild-type mice at comparable age.The functionality of P-glycoprotein of APP/PS1 mice did not change with age but was significantly lower than that of wild-type mice at 12 months of age.Decreased sphingomyelin levels,increased ceramide levels,and the increased expression and activity of neutral sphingomyelinase 1 were observed in APP/PS1 mice at 9 and 12 months of age compared with the levels in wild-type mice.Similar results were observed in the Alzheimer’s disease mouse model induced by intracerebroventricular injection of amyloid-β1-42 and human cerebral microvascular endothelial cells treated with amyloid-β1-42.In human cerebral microvascular endothelial cells,neutral sphingomyelinase 1 inhibitor interfered with the changes of sphingomyelin metabolism and P-glycoprotein expression and functionality caused by amyloid-β1-42 treatment.Neutral sphingomyelinase 1 regulated the expression and functionality of P-glycoprotein and the levels of sphingomyelin and ceramide.Together,these findings indicate that neutral sphingomyelinase 1 regulates the expression and function of P-glycoprotein via the sphingomyelin/ceramide pathway.These studies may serve as new pursuits for the development of anti-Alzheimer’s disease drugs.

Protocadherin gamma C3:a new player in regulating vascular barrier function

Defects in the endothelial cell barrier accompany diverse malfunctions of the central nervous system such as neurodegenerative diseases,stroke,traumatic brain injury,and systemic diseases such as sepsis,viral and bacterial infections,and cancer.Compromised endothelial sealing leads to leaking blood vessels,followed by vasogenic edema.Brain edema as the most common complication caused by stroke and traumatic brain injury is the leading cause of death.Brain microvascular endothelial cells,together with astrocytes,pericytes,microglia,and neurons form a selective barrier,the so-called blood-brain barrier,which regulates the movement of molecules inside and outside of the brain.Mechanisms that regulate blood-brain barrier permeability in health and disease are complex and not fully understood.Several newly discovered molecules that are involved in the regulation of cellular processes in brain microvascular endothelial cells have been described in the literature in recent years.One of these molecules that are highly expressed in brain microvascular endothelial cells is protocadherin gamma C3.In this review,we discuss recent evidence that protocadherin gamma C3 is a newly identified key player involved in the regulation of vascular barrier function.