Inhibition of viability of human retinal microvascular endothelial cells by vialinin A under high glucose condition

AIM:To investigate the effects of vialinin A on viability of human retinal endothelial cells(HRECs)under high glucose condition and its potential mechanism.METHODS:The HRECs were divided into four groups:normal glucose control group(NG,5 mmol/L D-glucose),high glucose group(HG,30 mmol/L D-glucose),HG+1μmol/L vialinin A group,and HG+5μmol/L vialinin A group.The cell viabilities were measured with cell counting kit-8(CCK-8)assay for proliferation,with scratch assay for migration,and tube formation,for evaluation of the impact of vialinin A on cellular behaviour.Real-time PCR and Western blotting were used to determine the expression level of vascular endothelial growth factor(VEGF).RESULTS:The proliferative capacity and migration of HRECs was reduced by 5μmol/L vialinin A in high glucose environment(both P<0.05).Vialinin A also inhibited highglucose-induced tube formation of HRECs.The expression level of VEGF and PI3K in HRECs was also significantly decreased by vialinin A(P<0.05).CONCLUSION:Vialinin A inhibits the cell viability of HRECs.It may serve as a potential target for anti-angiogenic therapy.

Analysis and comparison of retinal vascular parameters under different glucose metabolic status based on deep learning

AIM:To develop a deep learning-based model for automatic retinal vascular segmentation,analyzing and comparing parameters under diverse glucose metabolic status(normal,prediabetes,diabetes)and to assess the potential of artificial intelligence(AI)in image segmentation and retinal vascular parameters for predicting prediabetes and diabetes.METHODS:Retinal fundus photos from 200 normal individuals,200 prediabetic patients,and 200 diabetic patients(600 eyes in total)were used.The U-Net network served as the foundational architecture for retinal arteryvein segmentation.An automatic segmentation and evaluation system for retinal vascular parameters was trained,encompassing 26 parameters.RESULTS:Significant differences were found in retinal vascular parameters across normal,prediabetes,and diabetes groups,including artery diameter(P=0.008),fractal dimension(P=0.000),vein curvature(P=0.003),C-zone artery branching vessel count(P=0.049),C-zone vein branching vessel count(P=0.041),artery branching angle(P=0.005),vein branching angle(P=0.001),artery angle asymmetry degree(P=0.003),vessel length density(P=0.000),and vessel area density(P=0.000),totaling 10 parameters.CONCLUSION:The deep learning-based model facilitates retinal vascular parameter identification and quantification,revealing significant differences.These parameters exhibit potential as biomarkers for prediabetes and diabetes.

Anti-vascular endothelial growth factor drugs combined with laser photocoagulation maintain retinal ganglion cell integrity in patients with diabetic macular edema: study protocol for a prospective, non-randomized, controlled clinical trial

The integrity of retinal ganglion cells is tightly associated with diabetic macular degeneration that leads to damage and death of retinal ganglion cells,affecting vision.The major clinical treatments for diabetic macular edema are anti-vascular endothelial growth factor drugs and laser photocoagulation.However,although the macular thickness can be normalized with each of these two therapies used alone,the vision does not improve in many patients.This might result from the incomplete recovery of retinal ganglion cell injury.Therefore,a prospective,non-randomized,controlled clinical trial was designed to investigate the effect of anti-vascular endothelial growth factor drugs combined with laser photocoagulation on the integrity of retinal ganglion cells in patients with diabetic macular edema and its relationship with vision recovery.In this trial,150 patients with diabetic macular edema will be equally divided into three groups according to therapeutic methods,followed by treatment with anti-vascular endothelial growth factor drugs,laser photocoagulation therapy,and their combination.All patients will be followed up for 12 months.The primary outcome measure is retinal ganglion cell-inner plexiform layer thickness at 12 months after treatment.The secondary outcome measures include retinal ganglion cell-inner plexiform layer thickness before and 1,3,6,and 9 months after treatment,retinal nerve fiber layer thickness,best-corrected visual acuity,macular area thickness,and choroidal thickness before and 1,3,6,9,and 12 months after treatment.Safety measure is the incidence of adverse events at 1,3,6,9,and 12 months after treatment.The study protocol hopes to validate the better efficacy and safety of the combined treatment in patients with diabetic macula compared with the other two monotherapies alone during the 12-month follow-up period.The trial is designed to focus on clarifying the time-effect relationship between imaging measures related to the integrity of retinal ganglion cells and best-corrected visual acuity.The trial protocol was approved by the Medical Ethics Committee of the Affiliated Hospital of Beihua University with approval No.(2023)(26)on April 25,2023,and was registered with the Chinese Clinical Trial Registry(registration number:ChiCTR2300072478,June 14,2023,protocol version:2.0).

Ultrasound-targeted cationic microbubble-mediated gene transfection and inhibition of retinal neovascularization

AIM:To investigate whether ultrasound-targeted cationic microbubbles(CMBs)destruction could deliver endostatingreen fluorescent protein(GFP)plasmids efficiently to the human retinal endothelial cells(HRECs)and inhibit retinal neovascularization in mice.METHODS:CMBs were prepared and the presentation of GFP reporter was confirmed by flow cytometry and laser confocal microscopy.Experiments assessing HRECs migration and vascular formation were per formed to evaluate gene therapy’s efficiency in vitro.A mouse model of oxygen-induced retinopathy was employed and the expression of Bcl-xl,Bcl-2,vascular endothelial growth factor(VEGF)and endostatin in the retina of mice were determined by Western blotting and quantitative polymerase chain reaction(q PCR).The expression of endostatin-GFP in the retina was examined by laser confocal microscopy at 5,14,and 28 d after treatment.RESULTS:The gene expression of endostatin was the highest in the group of the CMBs.Besides,the inhibition and antiangiogenesis effect of the migration and development of HRECs were improved following treatment with CMBs compared with the other groups in vitro.In vivo,retinal neovascularization was significantly inhibited and the fluorescence intensity of endostatin-GFP in the mouse retina was importantly higher in the group of CMBs than that in other groups.CONCLUSION:The research illustrates ultrasoundtargeted CMBs destruction possessed distinct effect on the inhibition of the vascular formation and the development of retinal neovascularization both in vitro and in vivo.

Anomalous retinal artery associated with branch retinal artery occlusion and neovascular glaucoma: A case report

BACKGROUND Congenital anomalous retinal artery is rare and does not typically affect visual acuity.However,an abnormal artery that passes through and supplies blood to the macular area complicated with branch retinal artery occlusion may negatively impact visual acuity.This study reports an unusual case of anomalous retinal artery combined with retinal artery occlusion.CASE SUMMARY A 52-year-old male presented with severely reduced vision in the right eye.The fundus examination revealed an anomalous artery,extending from the superior temporal arcade and crossing the macula into the inferior temporal quadrant.The anomalous artery was partially occluded,with a narrowed lumen.A cherry-red spot was observed with whitening of the macular area,suggesting macular edema.Fundus fluorescein angiography revealed disc leakage and a delayed filling time.Optical coherence tomography revealed increased thickness of the neuroretina and underlying layers.The patient was treated with vessel dilation,hyperbaric oxygen,ocular massage,and thrombolytics.Visual acuity of the right eye subsequently improved to 20/200 from hand motion at 4 cm.This improvement in visual acuity persisted when the patient was examined at the 1-mo follow-up visit.The patient was subsequently followed via telephone interview.The information provided via interview indicated that visual acuity in the affected eye was stable up to 6 years from the time of the initial presentation.However,after 3 additional years,the patient was diagnosed with neovascular glaucoma in the right eye,which was subsequently enucleated.CONCLUSION Although congenital retinal vascular anomaly,including anomalous retinal artery,rarely affects vision,when complicated with branch retinal artery occlusion,the abnormal artery that supplies the macula may severely reduce visual acuity.

Inhibition of VEGF-A expression in hypoxia-exposed fetal retinal microvascular endothelial cells by exosomes derived from human umbilical cord mesenchymal stem cells

Objective:This study aimed to investigate the potential of human umbilical cord mesenchymal stem cell(hucMSC)-derived exosomes(hucMSC-Exos)in inhibiting hypoxia-induced cell hyper proliferation and overexpression of vascular endothelial growth factor A(VEGF-A)in immature human fetal retinal microvascular endothelial cells(hfRMECs).Methods:Exosomes were isolated from hucMSCs using cryogenic ultracentrifugation and characterized through various techniques,including transmission electron microscopy,nanoparticle tracking analysis,bicinchoninic acid assays,and western blotting.The hfRMECs were identified using von Willebrand factor(vWF)co-staining and divided into four groups:a control group cultured under normoxic condition,a hypoxic model group,a hypoxic group treated with low-concentration hucMSC-Exos(75μg/mL)and a hypoxic group treated with high-concentration hucMSC-Exos(100μg/mL).Cell viability and proliferation were assessed using Cell Counting Kit-8(CCK-8)assay and EdU(5-ethynyl-2′-deoxyuridine)assay respectively.Expression levels of VEGF-A were evaluated using RT-PCR,western blotting and immunofluorescence.Results:Hypoxia significantly increased hfRMECs’viability and proliferation by upregulating VEGF-A levels.The administration of hucMSC-Exos effectively reversed this response,with the high-concentration group exhibiting greater efficacy compared to the lowconcentration group.Conclusion:In conclusion,hucMSC-Exos can dose-dependently inhibit hypoxia-induced hyperproliferation and VEGF-A overexpression in immature fetal retinal microvascular endothelial cells.

The human retinal stem niches could overlap a vascular anatomical pattern

Stem cells are undifferentiated cells which have the unique potential to self-renew and to supply, via intermediate stages of transit amplifying cells （TACs）, differentiated cells. With- in the stem cell niches not only heterologous cells, but also differentiated progeny of stem cells provide regulation to the stem cells parents. Stem cells can differentiate in various cell types during tissue maintenance or repair.

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.

Regulation role of miR-204 on SIRT1/VEGF in metabolic memory induced by high glucose in human retinal pigment epithelial cells

AIM:To examine the regulatory role of microRNA-204(miR-204)on silent information regulator 1(SIRT1)and vascular endothelial growth factor(VEGF)under highglucose-induced metabolic memory in human retinal pigment epithelial(hRPE)cells.METHODS:Cells were cultured with either normal(5 mmol/L)or high D-glucose(25 mmol/L)concentrations for 8d to establish control and high-glucose groups,respectively.To induce metabolic memory,cells were cultured with 25 mmol/L D-glucose for 4d followed by culture with 5 mmol/L D-glucose for 4d.In addition,exposed in 25 mmol/L D-glucose for 4d and then transfected with 100 nmol/L miR-204 control,miR-204 inhibitor or miR-204 mimic in 5 mmol/L D-glucose for 4d.Quantitative reverse transcription-polymerase chain reaction(RT-qPCR)was used to detect miR-204 mRNA levels.SIRT1 and VEGF protein levels were assessed by immunohistochemical and Western blot.Flow cytometry was used to investigate apoptosis rate.RESULTS:It was found that high glucose promoted miR-204 and VEGF expression,and inhibited SIRT1 activity,even after the return to normal glucose culture conditions.Upregulation of miR-204 promoted apoptosis inhibiting SIRT1 and increasing VEGF expression.However,downregulation of miR-204 produced the opposite effects.CONCLUSION:The study identifies that miR-204 is the upstream target of SIRT1and VEGF,and that miR-204 can protect hRPE cells from the damage caused by metabolic memory through increasing SIRT1 and inhibiting VEGF expression.

Effect of acetyl L-carnitine on human retinal pigment epithelium-19 cells in hypoxic conditions

AIM:To investigate the effect of acetyl-L-carnitine(ALCAR)on cell viability,morphological integrity,and vascular endothelial growth factor(VEGF)expression in human retinal pigment epithelium(ARPE-19)cells using a hypoxic model.METHODS:In the first set of experiments,the optimal CoCl_(2) dose was determined by exposing ARPE-19 cell cultures to different concentrations.To evaluate the effect of ALCAR on cell viability,five groups of ARPE-19 cell culture were established that included a control group,a sham group(200μM CoCl_(2)),and groups that received 1,10 and 100 mM doses of ALCAR combined with 200μM CoCl_(2),respectively.The cell viability was measured by MTT assay.The morphological characteristics of cells were observed by an inverted phase contrast microscope.The levels of VEGF and HIF-1α secretion by ARPE-19 cells were detected by enzyme linked immunosorbent assay(ELISA)assay.RESULTS:ARPE-19 cells were exposed to different doses of CoCl_(2) in order to create a hypoxia model.Nevertheless,when exposed to a concentration of 200μM CoCl_(2),a notable decrease in viability to 83% was noted.ALCAR was found to increase the cell viability at 1 mM and 10 mM concentrations,while the highest concentration(100 mM)did not have an added effect.The cell viability was found to be significantly higher in the groups treated with a concentration of 1 mM and 10 mM ALCAR compared to the Sham group(P=0.041,P=0.019,respectively).The cell viability and morphology remained unaffected by the greatest dose of ALCAR(100 mM).The administration of 10 mM ALCAR demonstrated a statistically significant reduction in the levels of VEGF and HIF-1α compared with the Sham group(P=0.013,P=0.033,respectively).CONCLUSION:The findings from the current study indicate that ALCAR could represent a viable therapeutic option with the potential to open up novel treatment pathways for retinal diseases,particular relevance for age-related macular degeneration(AMD).However,to fully elucidate ALCAR’s application potential in retinal diseases,additional investigation is necessary to clearly define the exact mechanisms involved.

Impact of Lycium Barbarum Polysaccharide and Danshensu on vascular endothelial growth factor in the process of retinal neovascularization of rabbit

AIM:To discuss the impact of Lycium Barbarum Polysaccharide (LBP) and Danshensu purified from Traditional Chinese Medicine (TCM) on vascular endothelial growth factor (VEGF) of rabbits with retinal neovascularization. METHODS:Forty rabbits were divided into normal control group, model control group, LBP group and Danshensu group. Animals in the normal control group were fed in the normal oxygen environment. Animals in the other three groups were put into the environment with 70% oxygen for 5 days in order to build the model of oxygen-induced vascular proliferation retinopathy. And then different TCM extract was injected into the abdominal cavities of these annimals. After 7 days, the VEGF content of in the serum of rabbit was measured by double antibody sandwich method. RESULTS:Data analysis indicated that VEGF content was as follows:Danshensu group was lower than model control group (12.92 ±3.84ng/L vs 19.32 ±4.15ng/L, P 【 0.05); LBP group and normal control group were lower than model control group (12.92±3.84ng/L, 9.26±1.61ng/L vs 19.32±4.15ng/L, P【0.01); total blood viscosity, plasma viscosity, cholesterol content, fibrinogen content and triacylglycerol content after peritoneal injection of LBP and Danshensu were obviously lower than before injection. CONCLUSION:TCM extract-LBP and Danshensu can prominently reduce the content of VEGF in the process of vascular proliferative retinopathy of rabbit; can prevent the occurrence of retinal microvascular disease by improving partial oxygen -deficient environment or affecting all kinds of new growth factor.

Inhibition of LY294002 in retinal neovascularization via down-regulation the PI3K/AKT-VEGF pathway in vivo and in vitro

AIM： To investigate the effects of the phosphatidylinositol 3-kinase（PI3 K） inhibitor LY294002 on retinal neovascularization（RNV） in the oxygen-induced retinopathy（OIR） mouse model and human umbilical vein endothelial cells（HUVECs）.METHODS： C57 BL/6 J mice were randomly divided into normoxia-control, OIR-control and LY294002 treatment groups. LY294002 or phosphate-buffered solution was intraperitoneally injected daily into mouse pups from P6 to P9 in LY294002 treatment group or OIR-control group. Morphological and pathological changes in RNV, as well as expression levels of PI3 K, serine-threonine kinase（AKT） and vascular endothelial growth factor（VEGF） were observed. HUVECs treating with LY294002 were exposed to hypoxia; the expression of PI3 K, AKT and VEGF were examined by Western blot and RT-PCR analyses.RESULTS： Compared with the OIR-control group, LY294002 significantly inhibit RNV. Adenosine diphosphatase（ADPase） staining and hematoxylin and eosin staining indicated that the clock hour scores of neovascularization and the nuclei of pre-retinal neovascular cells in the LY294002 treatment group were clearly less than those in the OIR-control group（1.41±0.52 vs 6.20±1.21; 10.50±1.58 vs 22.25±1.82, both P〈0.05）. Intravitreal injection of LY294002（in the LY294002 treatment group） markedly decreased PI3 K/AKT-VEGF expression compared with the OIR-control group by immunohistochemistry, Western blotting and RT-PCR（all P〈0.05）. In HUVECs treated with hypoxia, expression of PI3 K, AKT and VEGF were downregulated in the hypoxia-LY294002 group（all P〈0.05）.CONCLUSION： The PI3 K inhibitor LY294002 can inhibit RNV by downregulating PI3 K, AKT, and VEGF expression in vivo and in vitro. LY294002 may provide an effective method for preventing retinopathy of prematurity（ROP）.

MicroRNA signature and function in retinal neovascularization

Ischemic retinopathies are clinically well-defined chronic microvascular complications characterized by gradually progressive alterations in the retinal microvasculature and a compensatory aberrant neovascularization of the eye. The subsequent metabolic deficiencies result in structural and functional alterations in the retina which is highly susceptible to injurious stimuli such as diabe-tes, trauma, hyperoxia, inflammation, aging and dys-plipidemia. Emerging evidence indicates that an effec-tive therapy may require targeting multiple components of the angiogenic pathway. Conceptually, mircoRNA(miRNA)-based therapy provides the rationale basis for an effective antiangiogenic treatment. miRNAs are an evolutionarily conserved family of short RNAs, each regulating the expression of multiple protein-coding genes. The activity of specific miRNAs is important for vascular cell signaling and blood vessel formation and function. Recently, important progress has been made in mapping the miRNA-gene target network andmiRNA-mediated gene expression control. Here wehighlight the latest findings on angiogenic and antian-giogenic miRNAs and their targets as well as potentiaimplications in ocular neovascular diseases. Emphasis isplaced on how specific vascular-enriched miRNAs regu-late cell responses to various cues by targeting severafactors, receptors and/or signaling molecules in orderto maintain either vascular function or dysfunction. Fur-ther improvement of our knowledge in not only miRNAspecificity, turnover, and transport but also how miRNAsequences and functions can be altered will enhancethe therapeutic utility of such molecules.

Small interfering RNA targeting PGC-1α inhibits VEGF expression and tube formation in human retinal vascular endothelial cells

AIMTo determine whether small interfering RNA (siRNA) of PGC-1α could inhibit vascular endothelial growth factor (VEGF) expression and tube formation in human retinal vascular endothelial cells (hRVECs).METHODShRVECs transfected with peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) siRNA were incubated for 24h and then placed into a normoxic (20%, O2) or hypoxic (1%, O2) environment for another 16h. PGC-1α mRNA and protein levels were detected by real-time PCR and Western blot. VEGF mRNA and protein levels were detected by real-time PCR and ELISA. Cell proliferation was evaluated by BrdU incorporation assay. Forty-eight hours after siRNA transfection, hRVECs were planted into Matrigel-coated plates and cultured under normoxic (20%, O2) or hypoxic (1%, O2) conditions for another 48h. The tube formation of hRVECs was observed under an optical microscope and quantified by counting the number of branch points and calculating the total tube length.RESULTSPGC-1α mRNA and protein levels were significantly reduced by PGC-1α siRNA, and VEGF mRNA and protein levels also decreased significantly. The percentage of BrdU-labeled cells in siPGC-1α groups were significantly decreased compared with control siRNA groups under normoxia and hypoxia in cell proliferation assay. In the tube formation assay, PGC-1α siRNA treated cells formed significantly fewer tubes.CONCLUSIONBlocking PGC-1α expression can inhibit VEGF expression in hRVECs and inhibit their ability to form tubes under both normoxic and hypoxic conditions.

The process of retinal vascularization in retinopathy of prematurity after ranibizumab treatment in China

AIM: To explore the process of retinal vascularization and risk factors for retinopathy of prematurity(ROP) treated with intravitreal ranibizumab(IVR) as monotherapy.METHODS: Infants with type 1 ROP who received IVR as primary treatment from August 2014 to October 2016 at Peking University People’s Hospital’s Ophthalmology Department were included in the study. All eyes received 0.25 mg ranibizumab at initial treatment. Retinal vascularization was evaluated clinically. Potential risk factors were also recorded and examined.RESULTS: Retinal vascularization was completed in 126 eyes(62.7%), and retinal vascularization terminated in zone II and zone III with 16 eyes(7.9%) and 44 eyes(21.9%), respectively, after more than 1-year follow-up. In multivariate regression analysis, lower birth weight(BW), severity of ROP and repeated injections were found to be risk factors for peripheral avascular area(P<0.05). CONCLUSION: In our retrospective study, 29.8% of the ROP eyes treated with ranibizumab have peripheral avascular area at the last follow-up. Lighter BW and the severity of ROP are risk factors. Furthermore, repeated injections also increase the risk of retinal peripheral avascular area remaining in ROP patients.

Inhibition of proliferation of retinal vascular endothelial cells more effectively than choroidal vascular endothelial cell proliferation by bevacizumab

AIM： To evaluate the differential inhibitory effects of bevacizumab on cell proliferation of vascular endothelial growth factor （VEGF）-stimulated choroidal vascular endothelial cells （CVECs） and retinal vascular endothelial cells （RVECs） in vitro.METHODS： VEGF （400 ng/mL） enriched CVECs and RVECs were treated with escalating doses of bevacizumab （0.1, 0.5, 1, 1.5 and 2 mg/mL）. Cell proliferation changes were analyzed with WST-1 assay and trypan blue exclusion assay at 48, 72h and 1wk. Morphological changes were recorded with bright field microscopy.RESULTS： VEGF enriched RVECs showed significantly more decline of cell viability than CVECs after bevacizumab treatment. One week after treatment, RVEC cell proliferation decreased by 29.7%, 37.5%, 52.8%, 35.9% and 45.6% at 0.1, 0.5, 1.0, 1.5 and 2 mg/mL bevacizumab respectively compared to CVEC proliferation decrease of 4.1%, 7.7%, 2.4%, 4.1% and 17.7% （P〈0.05） by WST-1 assay. Trypan blue exclusion assay also revealed similar decrease in RVEC proliferation of 20%, 60%, 73.3%, 80% and 93.3% compared to CVEC proliferation decrease of 4%, 12%, 22.9%, 16.7% and 22.2% respectively （P〈0.05）. The maximum differential effect between the two cell types was observed at bevacizumab doses of 1.0 and 1.5 mg/mL at all time points. RVECs were 22 fold more sensitive （P〈0.01） compared to CVECs （52.8% vs 2.4%） at concentration of 1.0 mg/mL, and 8.7 fold more at 1.5 mg/mL （35.9% vs 4.1%） 1wk after treatment （P〈0.05 respectively）.CONCLUSION： VEGF-enriched RVECs are more susceptible to bevacizumab inhibition than CVECs at clinically used dosage of 1.25 mg and this differential sensitivity between two cell types should be taken into consideration in dosage selection.

Matrix metalloproteinase-9 and vascular endothelial growth factor expression change in experimental retinal neovascularization

AIM： To investigate the signal transduction mechanism of matrix metalloproteinase-9 （MMP-9） mediatedvascular endothelial growth factor （VEGF） expression and retinal neovascularization （RNV） in oxygen-induced retinopathy （OIR） model. METHODS： C57BL/6J mice were divided into four groups： control group, OIR group, OIR control group （phosphatebuffered saline by intravitreal injection） and treated group [tissue inhibitor of matrix metalloproteinase-1 （TIMP-1） by intravitreal injection]. OIR model was established in C57BIJ6J mice exposed to 75% ＋2% oxygen for 5d. mRNA level and protein expression of MMP-9, TIMP-1 and VEGF were measured by real-time polymerase chain reaction and Western blotting, and located by immunohistochemistry. RESULTS： Levels of MMP-9 and VEGF in retina were significantly increased in animals with OIR and OIR control group. Levels of TIMP -1 in retina was significantly reduced in animals with OIR and OIR control group. Furthermore, a significant correlation was found between MMP-9 and VEGF. Intravitreal injection of TIMP- 1 significantly reduced MMP-9 and VEGF expression of the OIR mouse model （all P〈0.05）. CONCLUSION： These results demonstrate that MMP- 9-mediated up-regulation of VEGF promotes RNV in retinopathy of prematurity （ROP）. TIMP-1 may be a potential target for the prevention and treatment of ROP.

Mesenchymal stem cell-derived exosomes inhibit the VEGF-A expression in human retinal vascular endothelial cells induced by high glucose

AIM:To determine the effect of exosomes derived from human umbilical cord blood mesenchymal stem cells(hUCMSCs)on the expression of vascular endothelial growth factor A(VEGF-A)in human retinal vascular endothelial cells(HRECs).METHODS:Exosomes were isolated from hUCMSCs using cryogenic ultracentrifugation and characterized by transmission electron microscopy,Western blotting and nanoparticle tracking analysis.HRECs were randomly divided into a normal control group(group A),a high glucose model group(group B),a high glucose group with 25μg/mL(group C),50μg/mL(group D),and 100μg/mL exosomes(group E).Twenty-four hours after coculture,the cell proliferation rate was detected using flow cytometry,and the VEGF-A level was detected using immunofluorescence.After coculture 8,16,and 24h,the expression levels of VEGF-A in each group were detected using PCR and Western blots.RESULTS:The characteristic morphology(membrane structured vesicles)and size(diameter between 50 and 200 nm)were observed under transmission electron microscopy.The average diameter of 122.7 nm was discovered by nanoparticle tracking analysis(NTA).The exosomal markers CD9,CD63,and HSP70 were strongly detected.The proliferation rate of the cells in group B increased after 24h of coculture.Immunofluorescence analyses revealed that the upregulation of VEGF-A expression in HRECs stimulated by high glucose could be downregulated by cocultured hUCMSC-derived exosomes(F=39.03,P<0.01).The upregulation of VEGF-A protein(group C:F=7.96;group D:F=17.29;group E:F=11.89;8h:F=9.45;16h:F=12.86;24h:F=42.28,P<0.05)and mRNA(group C:F=4.137;group D:F=13.64;group E:F=22.19;8h:F=7.253;16h:F=16.98;24h:F=22.62,P<0.05)in HRECs stimulated by high glucose was downregulated by cocultured hUCMSC-derived exosomes(P<0.05).CONCLUSION:hUCMSC-derived exosomes downregulate VEGF-A expression in HRECs stimulated by high glucose in time and concentration dependent manner.

Regulation of opticin on bioactivity of retinal vascular endothelial cells cultured in collagen

AIM:To investigate the effects of collagen and opticin on the bioactivity of human retinal vascular endothelial cells(hR VECs),and explore its regulations by integrins and RhoA/ROCK1 signal pathway.METHODS:h RVECs were cultured in collagen and treated by opticin,and cell-based bioactivity assays of cell proliferation,migration,and adhesion were performed.The expression of integrinα2,integrinβ1,Rho A and ROCK1 were examined with real-time PCR and Western blotting.RESULTS:Collagen could promote cell viability of proliferation and migration(all P<0.05),and enhance the m RNA expression of integrinα2,integrinβ1,Rho A and ROCK1(all P<0.05).Opticin could inhibit proliferation and migration ability of hR VECs cultured in collagen,and reduce the mR NA expression of integrinα2,integrinβ1,RhoA and ROCK1(all P<0.05).CONCLUSION:Collagen and opticin can affect bioactivity of hR VECs,which may be regulated byα2-,β1-integrins and RhoA/ROCK1 signal pathway.

Complications of Ziv-Aflibercept in Choroidal and Retinal Vascular Diseases

Introduction: The modern ophthalmology trends are changing rapidly every day with the introduction of much newer studies and research. Numerous anti-vascular endothelial growth factors (VEGF) are utilized as the mainstay in the treatment of intraocular vascular pathologies. The rationale of this study is to add to the literature regarding the safety and efficacy profile of the ziv-aflibercept as there is insubstantial data in patients with intraocular vascular pathologies being treated with this injection with prime focus on the complications of the injection. Materials and Methods: A prospective observational study was conducted at Opthalmology Department, Lahore General Hospital, Lahore between 14 August 2018 and 23 December 2019. Patients with choroidal and retinal vascular diseases like diabetic macular edema (DME), age-related macular degeneration (AMD) and retinal vein occlusion (RVO) who had no active infection of eye and had no history of myocardial infarction or cerebrovascular accident were added in this study. Results: Best-corrected visual acuity was significantly improved at 4, 8, and 12 weeks as compared to the baseline (p Conclusion: The use of ziv-aflibercept injection via intravitreal route under aseptic conditions for choroidal and retinal vascular diseases is effective as well as safe with mild and treatable ocular side effects.