Subconjunctival conbercept for the treatment of corneal neovascularization

·AIM:To investigate the effectiveness and safety of subconjunctival injection of conbercept in the treatment of corneal neovascularization(CNV).·METHODS:The data on 10 consecutively recruited patients with CNV who received a subconjunctival conbercept(1 mg)once,and measured the area,length,and diameter of neovascularization before and after(1d,1,2wk,and 1mo)treatment as well as the occurrence of systemic and ocular complications after treatment were analyzed.·RESULTS:There was a statistically significant reduction in the area of CNV one day after treatment(mean±SD:38.46±11.36 mm^(2)),compared with before treatment(42.46±12.80 mm^(2),P<0.01).There was also a statistically significant reduction in the length(3.86±1.80 mm vs 4.64±1.77 mm,P<0.01)and diameter(0.044±0.022 vs 0.060±0.026,P<0.05)of CNV,one week after treatment comparing to before treatment.The reduction in all three parameters was maximized at two weeks after treatment(area:29.49±8.83 mm^(2),P<0.001;length:3.50±1.88 mm,P<0.001;and diameter:0.038±0.017 mm,P<0.01).No severe systemic or ocular complication was observed during the study.·CONCLUSION:During the observation period of onemonth,subconjunctival injection of conbercept is an effective and safe method for the reduction of CNV.It may be effective as a preoperative drug for neovascular corneal transplantation.

Efficacy and safety of anti-vascular endothelial growth factor agents on corneal neovascularization: A meta-analysis

BACKGROUND Corneal neovascularization(CoNV)is the second major cause of blindness.Vascular endothelial growth factor(VEGF)inhibitors,e.g.,bevacizumab,have been used to prevent CoNV.AIM We conducted an updated systematic review and meta-analysis of clinical trials to examine the efficacy and safety of anti-VEGF in CoNV.METHODS A literature search was conducted using three electronic databases.Mean difference(MD),standard mean difference(SMD),and relative risk(RR)are used to estimate the effect size.RESULTS Nine randomized controlled and three non-randomized trials were obtained.The pooled results demonstrated a significant reduction of CoNV area/Length(SMD=-1.17,95%CI:-1.58 to-0.75),best corrected visual acuity(MD=-0.54,95%CI:-0.91 to-0.17),and graft rejection(RR=0.44,95%CI:0.24 to 0.8)and failure(RR=0.39,95%CI:0.19 to 0.78)rates in the anti-VEGF group than the placebo group.A non-significant reduction of the epithelial defect was also observed in the bevacizumab group compared with the placebo(RR=0.56,95%CI:0.30 to 1.06).Compared with a placebo,the unsynthesizable trials also support that bevacizumab improves visual acuity,CoNV,graft rejection,and failure rates.Trials reporting other comparisons revealed the superiority of combined remedy with bevacizumab compared to other treatments in reducing CoNV.CONCLUSION Anti-VEGF agents,mainly bevacizumab,are an effective and safe treatment for CoNV of all causes and prevent corneal graft rejection and failure in corneal transplantation.

Comparison of subconjunctivally injected bevacizumab, ranibizumab, and pegaptanib for inhibition of corneal neovascularization in a rat model

AIM: To compare the efficacies of subconjunctival bevacizumab, ranibizumab, and pegaptanib sodium injections for the inhibition of corneal neovascularization in an experimental rat model. METHODS: Sixteen corneas of 16 rats were chemically cauterized and randomized into four groups: bevacizumab group that treated with 0.05mL/1.25mg bevacizumab, ranibizumab group that treated with 0.05mL/0.5mg ranibizumab, pegaptanib group that treated with 0.05mL/0.15mg pegaptanib sodium, and control group that treated with 0.05mL saline solution. Digital photographs of the corneas were taken and analyzed using an image analysis software program. All corneas were excised and examined histologically on the 15 th day. RESULTS: Each treatment group had significantly less neovascularized corneal areas and fewer blood vessels than the control group (all P 【0.05). In addition, bevacizumab group had significantly less neovascu-larized corneal areas and fewer blood vessels than ranibizumab and pegaptanib groups (both P 【0.05). However, there was no significant difference between the ranibizumab and pegaptanib groups regarding percentage of neovascularized corneal areas and number of blood vessels (both P 】0.05). CONCLUSION: Subconjunctival bevacizumab, ranibiz-umab, and pegaptanib sodium were effective with no corneal epitheliopathy for inhibiting corneal neovascularization after corneal burn in rats .Bevacizumab was more effective than ranibizumab and pegaptanib sodium.

Comparison of the inhibitory effect of different doses of subconjunctival bevacizumab application in an experimental model of corneal neovascularization

AIM： To evaluate the inhibitory effect of subconjunctival bevacizumab as single-and multiple-dose application, and compare their effects on corneal neovascularization in a rat model. METHODS： Thirty adult Sprague-Dawley rats were used in this experimental study. The central cornea of the rats was cauterized chemically. The rats were randomly enrolled into three groups. All groups received subconjunctival injections. In Group 1（control group, n=10）, 0.05 m L 0.9% Na Cl solution was injected on the first day. In Group 2（single-dose group, n=10）, 0.05 m L bevacizumab（1.25 mg） was injected on the first day. In Group 3（multiple-dose group, n=10）, four doses of 0.05 m L bevacizumab（1.25 mg） were injected on the first, third, fifth and seventh day. Slit-lamp examination of all rats was performed at the third and ninth day. Digital images of the corneas were taken and analyzed using image analysis software to calculate corneal neovascularization area. All rats were sacrificed on the tenth day. In corneal sections, the number of blood vessels, state of inflammation and collagen formation was evaluated histopathologically. RESULTS： In Group 3, corneal edema grades were significantly lower than Group 1 and Group 2（P=0.02, and P=0.035, respectively）. The mean percentage of neovascularized corneal area in Group 3 was significantly lower than Group 2（P=0.005）. On histopathological examination, Group 2 and Group 3 showed significantly less number of blood vessels than Group 1（P=0.005, and P=0.001, respectively）. Additionally, Group 3 showed significantly less number of blood vessels compared to Group 2（P=0.019）. Inflammation and edema grades were significantly lower in Group 3 compared to Group 1（P=0.001）. CONCLUSION： Subconjunctival bevacizumab injection is effective in inhibition of newly formed corneal neovascularization. The multiple-dose bevacizumab treatment seems to be more effective compared to single-dose treatment.

Inhibitory effect of CCR3 signal on alkali-induced corneal neovascularization

AIM: To investigate the effect of CC chemokine receptor 3 (CCR3) signal on corneal neovascularization (CRNV) induced by alkali burn and to explore its mechanism. METHODS: Specific pathogen-free male BALB/C mice (aged 6-8 weeks) were randomly divided into CCR3-antagonist treated group (experimental group) and control group. CRNV was induced by alkali burn in mice. The time kinetic CCR3 expression in injured corneas was examined by reverse transcription polymerase chain reaction (RT-PCR). CCR3-antagonist (SB-328437 at different concentration of 125 mu g/mL, 250 mu g/mL, and 500 mu g/mL) was locally administrated after alkali injury. The formation of CRNV was assessed by CD31 corneal whole mount staining at two weeks after injury. Monocyte chemotactic protein 1 (MCP-1), monocyte chemotactic protein 3 (MCP-3) expressions in the early phase after injury were quantified and compared by RT-PCR. Macrophage intracorneal accumulation in the early phase after injury was evaluated and compared by immunohistochemistry. RESULTS: Alkali injury induced the time kinetic intracorneal CCR3 expression. 500 mu g/mL of CCR3-antagonist treatment in the early phase but not the late phase resulted in significant impaired CRNV as compared to control group (P <0.05). CCR3-antagonist treatment in the early phase significantly reduced the intracorneal MCP-1 and MCP-3 enhancement compare to control group at day 2 and day 4 (P <0.05). Moreover, the number of intracorneal macrophage infiltration in the experimental group was reduced than those in control group at day 4 (P <0.05). CONCLUSION: CCR3 signal is involved in alkali-induced CRNV. CCR3-antagonist can inhibit alkali-induced CRNV by reducing the intracorneal MCP-1 and MCP-3 mRNA expression and the intracorneal macrophage infiltration.

Comparison of the therapeutic effects of extracts from Spirulina platensis and amnion membrane on inflammation-associated corneal neovascularization

AIM: To compare the therapeutic effects of polysaccharide extract from Spirulina platensis (PSP) and extract from amnion membrane CAME) on alkali burn-induced corneal neovascularization (CorNV). METHODS: PSP and AME were Extracted from dry powder of Spirulina platensis and human aminion membrane respectively. Murine CorNV was induced by applying 1N sodiumhydroxide (NaOH) solution directly on the mice corneas. PSP and AME extracts were administered topically on the corneas 4 times daily for 7 days. The therapy effects of PSP and AME extracts were evaluated daily using slit-lamp. At the end of the therapy, corneas were harvested for H&E staining, masson trichrome staining, immunohistochemical study, and semi-quantification reverse transcriptive PCR (RT-PCR) was utilized for measurement of inflammation-related molecules. RESULTS: Topical application of PSP extract had significant therapeutic effects on CorNV that could be shown in various assays of the corneas. Compared with AME Extract, PSP extract treatment was more effective in suppressing CorNV in berms of vessel length and levels of cluster of differentiation 31 (CD31) proteins or the angiogenesis related genes like vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP2) and matrix metalloproteinase-9 (MMP9). PSP also inhibited inflammation more markedly by more effectively inhibiting mononuclear and polymorphonuclear cells infiltration into the corneal stroma and reducing levels of stromal cell-derived factor-1 (SDF1), tumor necrosis factor-alpha (TNF alpha) and macrophage inflammatory protein-3 (MIP3a). In addition, corneas of PSP group had a more regular and compact architecture of collagen with thinner corneal thickness than in the AME group. ' CONCLUSION: Polysaccharide extract from Spirulina platensis inhibited alkali burn-induced inflammation and CorNV more effectively than AME Extract at the studied doses, thus may be used for the therapy of corneal diseases involving neovascularization and inflammation.

Suppression of corneal neovascularization by curcumin via inhibition of Wnt/β-catenin pathway activation

AIM：To investigate whether curcumin suppressed corneal neovascularization（CNV） formation via inhibiting activation of Wnt/β-catenin pathway.METHODS：Suture-induced CNV was established on Sprague-Dawley（SD） rats.Curcumin were daily administrated by subconjunctival injection.Phosphorylation of low-density lipoprotein receptor-related protein 6（LRP6） and nuclear accumulation of β-catenin,two indicators of activated Wnt/β-catenin pathway,were determined by Western-blot analysis in subconfl uent/proliferating human microvascular endothelial cells（HMEC） and neovascularized corneas.Wnt3 a conditioned medium（WCM） were harvested from Wnt3 a expressing cells.WCM-induced cell proliferation and endothelial tubular formation capacity was measured by MTT assay and Matrigel assay,respectively.RESULTS：Phosphorylation of LRP6 and nuclear accumulation of β-catenin was significantly increased in subconfluent/proliferating endothelial cells.Activation of Wnt/β-catenin pathway by WCM markedly promotes HMEC proliferation and tubular formation.Curcumin inhibited LRP6 phosphorylation and nuclear accumulation of β-catenin.In addition,curcumin attenuated WCM-induced HMEC proliferation and disrupted tubular structure of endothelial cells on Matrigel.Meanwhile curcumin suppressed suture-induced CNV and inhibited LRP6 phosphorylation as well as β-catenin accumulation in SD rats.CONCLUSION：Taken together,activation of Wnt/β-catenin pathway could be involved in endothelial proliferation during suture-induced CNV formation and curcumin attenuated CNV formation via inhibition of Wnt/β-catenin pathway activation.

Inhibitory effects of regorafenib, a multiple tyrosine kinase inhibitor, on corneal neovascularization

AIM:To evaluate the inhibitory effects of regorafenib(BAY 73-4506),a multikinase inhibitor,on corneal neovascularization(NV).METHODS:Thirty adult male Sprague-Dawley rats weighing 250-300 g,were used.Corneal NV was induced by NaOH in the left eyes of each rat.Following the establishment of alkali burn,the animals were randomized into five groups according to topical treatment.Group 1(n=6)received 0.9%NaCl,Group 2(n=6)received dimethyl sulfoxide,Group 3(n=6)received regorafenib 1 mg/mL,Group 4(n=6)received bevacizumab 5 mg/mL and Group 5(n=6)received 0.1%dexamethasone phosphate.On the 7d,the corneal surface covered with neovascular vessels was measured on photographs as the percentage of the cornea’s total area using computer-imaging analysis.The corneas obtained from rats were semiquantitatively evaluated for caspase-3 and vascular endothelial growth factor by immunostaining.RESULTS:A statistically significant difference in the percent area of corneal NV was found among the groups(P【0.001).Although the Group 5 had the smallest percent area of corneal NV,there was no difference among Groups 3,4 and 5(P】0.005).There was a statistically significant difference among the groups in apoptotic cell density(P=0.002).The staining intensity of vascular endothelial growth factor in the epithelial and endothelial layers of cornea was significantly different among the groups(P【0.05).The staining intensity of epithelial and endothelial vascular endothelial growth factor was significantly weaker in Groups 3,4 and 5 thanin Groups 1 and 2.CONCLUSION:Topical administration of regorafenib 1mg/mL is partly effective for preventing alkali-induced corneal NV in rats.

Effect of amnion membrane transplantation on corneal neovascularization in 10 patients with alkali burn

By observing clinical cases, we studied the curative effect of amnion membrane transplantation on decreasing corneal neovascularization (CNV). It was a non-randomized retrospective case-control study. Among 17 cases (21 eyes) of third-degree alkali burns from 2007 to 2010, 10 cases (12 eyes) were performed with amnion membrane transplantation operation, and others were not. Amnion membrane transplantation was performed at the 3rd day after burn in the treatment group. Areas of CNV in double groups were measured at the 14th day and 60th day after burn. Area of CNV in the treatment group was (66.207±7.251)mm2 at the 14th day after burn, and was 18.27% lower than that in the control group. Area of CNV in the treatment group was (120.046±13.812)mm2 at the 60th day after burn, and was 11.35% lower than that in the control group. There was both statistical significance (P<0.05). Amnion membrane transplantation operation can inhibit the growth of corneal neovascularization induced by alkali burn.

Effects of AMD3100 subconjunctival injection on alkali burn induced corneal neovascularization in mice

AIM: To investigate the therapeutic effects of local and systemic administration of AMD3100 for alkali burn induced corneal neovascularization (CNV) in mice. METHODS: CNV was induced in vivo by alkaline burn of cornea in C57BL/6 mice. AMD3100 was administrated topically by subconjunctival injection or systemically by intraperitoneal injection for 7 days; balanced salt solution was administrated topically or systemically as a control respectively. Inflammatory index was evaluated by slit-lamp biomicroscopy and inflammatory cells infiltrated to cornea tissue were detected by histologic analysis at multiple time points. CNV was compared between the local and systemic treated mice 2 weeks after alkali burn, as quantified by CD34 immunostaining. Fluorescence-Activated Cell Sorter Analysis was used to investigate the mobilizing effects of EPC in mice after subconjunctival injected or intraperitoneal injected AMD3100. Immunohistochemistry was used to detect the expression of endothelial progenitor cells (EPC) marker proteins VEGFR2 and CD34. RESULTS: Three days after alkali burn, infiltration of inflammatory cells was found in corneal tissue. At the first 7 days of local injection group, the number of inflammatory cells was significantly lower than that in systemic injection group. CNV could be seen at the 7(th) day, and at the 14(th) day reached the peak, then started to decrease. The number of CNV in the subconjunctival injection group was 7.57 +/- 1.26 per 0.034mm(2), compared to a number of 14.87 +/- 2.21 per 0.034mm(2) in the control group (P<0.05). On the contrary, the number of CNV in the intraperitoneal injection group was a little higher than that in the control group, 16.34 +/- 1.53 per 0.034mm(2) vs 13.26 +/- 1.87 per 0.034mm(2). The research also showed that intraperitoneally, but not subconjunctivally injected AMD3100 could mobilize EPC. On the other hand, subconjunctival, but not intraperitoneally injected AMD3100 could reduce the expression of EPC marker proteins. CONCLUSION: In mice locally administrated AMD3100 can reduce the number of alkali burn induced CNV. The number of inflammatory cells and inflammatory responses in corneal tissue.

Inhibited experimental corneal neovascularization by neutralizing anti-SDF-1α antibody

AIM: To explore the effect of SDF-1α on the development of experimental corneal neovascularization (CRNV).METHODS: CRNV was induced by alkali injury in mice. The expression of SDF-1α and CXCR4 in burned corneas was examined by Flow Cytometry. Neutralizing anti-mouse SDF-1α antibody was locally administrated after alkali injury and the formation of CRNV 2 weeks after injury was assessed by Immunohistochemistry. The expression of VEGF and C-Kit in burned corneas was detected by RT-PCR.RESULTS: The number of CRNV peaks at 2 weeks after alkali injury. Compared to control group, SDF-1α neutralizing antibody treatment significantly decreased the number of CRNV. RT-PCR confirmed that SDF-1α neutralizing antibody treatment resulted in decreased intracorneal VEGF and C-Kit expression.CONCLUSION: SDF-1α neutralizing antibody treated mice exhibited impaired experimental CRNV through down regulated VEGF and C-Kit expression.

Host immune cellular reactions in corneal neovascularization

Corneal neovascularization（CNV） is a global important cause of visual impairment. The immune mechanisms leading to corneal heme- and lymphangiogenesis have been extensively studied over the past years as more attempts were made to develop better prophylactic and therapeutic measures. This article aims to discuss immune cells of particular relevance to CNV, with a focus on macrophages, Th17 cells, dendritic cells and the underlying immunology of common pathologies involving neovascularization of the cornea. Hopefully, a thorough understanding of these topics would propel the efforts to halt the detrimental effects of CNV.

Inhibition of corneal neovascularization by topical application of nintedanib in rabbit models

AIM:To evaluate the potential efficacy and mechanisms of nintedanib in corneal neovascularization(NV)in rabbit models.METHODS:Corneal NV was induced using 1 mol/L Na OH.Rabbits(n=21)were randomized to 3 groups:Group 1 were treated with 0.9%NaCl,Group 2 with Avastin(5 mg/mL),and Group 3 with nintedanib(1 mg/mL).All treatments star ted 1 d af ter alkaline burns and were topically performed 3 times a day for 2 wk.Photographs were taken on a slit lamp microscope on day 7 and 14.The NV area,the length of the vascularization and angiogenesis index(AI)were used to evaluate the corneal NV.On day 14,the immunohistochemical(IHC)studies of the cornea were examined.Western blot was performed to test the expression levels of vascular endothelial growth factor(VEGF),Akt,p-Akt,P38,p-P38,MMP-2 and MMP-9.RESULTS:The corneal NV area,vessel length and AI in Group 3 were significantly lower than Group 2,with both being lower than Group 1.IHC staining showed that VEGF was significantly overexpressed in the epithelium and stroma of cornea following alkaline burns.In contrast,the level of VEGF was significantly suppressed in both Group 2 and Group 3.Western blot results further confirmed that,compared with Group 1,Group 3 had significantly reduced expressions of VEGF,Akt,p-Akt,p-P38,MMP-2,and MMP-9 in corneal tissues.Trends of lower levels of MMP-2,AKT,and p-AKT in Group 3 than Group 2 were identified.CONCLUSION:Nintedanib and Avastin can effectively inhibit corneal NV,with P38 MAPK and AKT signaling pathways being possibly involved.Nintedanib seems more effective than Avastin and has the potential to be a novel therapy for preventing corneal NV.

Attenuation of corneal neovascularization by topical low-molecular-weight heparin-taurocholate 7 without bleeding complication

AIM：To investigate the antiangiogenic effects and safety of topically administered low-molecular-weight heparintaurocholate 7（LHT7） on corneal neovascularization（CoNV）.METHODS：Twenty-four Sprague-Dawley rats were randomly distributed into four groups of six rats each.The central corneas were cauterized using a silver/potassium nitrate solution.From 2d after cauterization,12.5 mg/mL（low LHT7 group） or 25 mg/mL（high LHT7group） LHT7 was topically administered three times daily;12.5 mg/mL bevacizumab was topically administered as positive control（bevacizumab） group,with normal saline（NS） administered as negative control（NS group）.The corneas were digitally photographed to calculate the CoNV percentage from the neovascularized corneal area at 1 and 2wk.RESULTS：The 4 study groups did not have different CoNV percentages at 1wk after injury（P〉0.05）.However,the low LHT,high LHT,and bevacizumab groups had significantly lower CoNV percentages than the NS group at 2wk（all P〈0.05）.No significant differences in CoNV percentage were found among the low LHT,high LHT,and bevacizumab groups（all P〉0.05）.All groups except the NS group had lower CoNV percentages at 2wk postinjury than the levels observed at 1wk（all P〈0.05）.CONCLUSION：Topically-administered LHT7 inhibited CoNV without complication after chemical cauterization in the rat.

Quantification of corneal neovascularization after ex vivo limbal epithelial stem cell therapy

AIM: To assess cultured limbal epithelial stem cell transplantation in patients with limbal stem cell deficiency by analyzing and quantifying corneal neovascularization.METHODS: This retrospective, interventional case series included eight eyes with total limbal stem cell deficiency. Ex vivo limbal epithelial stem cells were cultured on human amniotic membrane using an animalfree culture method. The clinical parameters of limbal stem cell deficiency, impression cytology, and quantification of corneal neovascularization were evaluated before and after cultured limbal stem cell transplantation. The area of corneal neovascularization,vessel caliber(VC), and invasive area(IA) were analyzed before and after stem cell transplantation by image analysis software. Best-corrected visual acuity(BCVA),epithelial transparency, and impression cytology were also measured.RESULTS: One year after surgery, successful cases showed a reduction(improvement) of all three parameters of corneal neovascularization [neovascular area(NA), VC, IA], while failed cases did not. NA decreased a mean of 32.31%(P =0.035), invasion area29.37%(P =0.018) and VC 14.29%(P =0.072). BCVA improved in all eyes(mean follow-up, 76 ±21mo).Epithelial transparency improved significantly from 2.00 ±0.93 to 0.88±1.25(P =0.014). Impression cytology showed that three cases failed after limbal epithelial stem cell therapy before 1y of follow-up.CONCLUSION: This method of analyzing andmonitoring surface vessels is useful for evaluating the epithelial status during follow-up, as successful cases showed a bigger reduction in corneal neovascularization parameters than failed cases. Using this method,successful cases could be differentiated from failed cases.

The Active Metabolite of Leflunomide A771726 Inhibits Corneal Neovascularization

The effects of A771726, the active metabolite of leflunomide, on experimental rat corneal neovascularization （NV） in vivo and on cultured human umbilical vein endothelial cells in vitro were studied. The corneal NV was induced by alkali burn in 40 SD rats. The rats were randomly divided into 4 groups with 10 rats in each group. Group A was treated with 0.9% sodium chloride （control group）, and group B, group C and group D were given different concentrations of A771726 eye drops （0.5%, 1.0%, 2.0% respectively） 4 times daily during days 0--28. The occurrence and development of corneal NV were observed at 4, 7, 14, 21 and 28 day after alkali burn by a slit lamp microscope. The cultured human umbilical vein endothelial cells （ECV-304） were incubated with A771726 solution at different concentrations （20, 40, 80, 160, 320 μmol/L） for 36 h. The proliferation of cells was assessed by methyl thiazolyl tetrazolium （MTT）, and the expression of proliferating cell nuclear antigen （PCNA） in cells was detected by using immunofluorescence under the laser confocal microscope. The rat model showed that the onset of corneal NV was delayed and progression of corneal NV was inhibited in the groups C and D. The corneal NV areas in groups C and D were significantly smaller than in groups A and B （P〈0.01）. No significant difference was found in corneal NV areas between groups C and group D （P〉0.05）. A771726 solution （940 μmol/L） could inhibit proliferation of human umbilical vein endothelial cells and decrease the expression of PCNA in cells significantly, A771726, as the active metabolite of leflunomide, strongly prevented corneal NV induced by alkali burn in the in vivo model, and inhibited proliferation of human umbilical vein endothelial cells in the in vitro model. Therefore, A771726 may serve as an angiogenic inhibitor in the treatment of corneal NV.

Inhibitory effect of polysulfated heparin endostatin on alkali burn induced corneal neovascularization in rabbits

AIM: To investigate anti-angiogenic effects of polysulfated heparin endostatin(PSH-ES) on alkali burn induced corneal neovascularization(NV) in rabbits.METHODS: An alkali burn was made on rabbit corneas to induce corneal NV in the right eye of 24 rabbits. One day after burn creation, a 0.2 m L subconjunctival injection of 50 μg/m L PSH-ES, 50 μg/m L recombinant endostatin(ES), or normal saline was administered every other day for a total of 14d(7 injections). Histology and immunohistochemisty were used to examine corneas.Corneal NV growth was evaluated as microvessel quantity and corneal vascular endothelial growth factor(VEGF)expression was measured by immunohistochemical assay.RESULTS: Subconjunctival injection of ES and PSHES resulted in significant corneal NV suppression, but PSH-ES had a more powerful anti-angiogenic effect than ES. Mean VEGF concentration in PSH-ES treated corneas was significantly lower than in ES treated and saline treated corneas. Histological examination showed that corneas treated with either PSH-ES or ES had significantly fewer microvessels than eyes treated with saline. Additionally corneas treated with PSH-ES had significantly fewer microvessels than corneas treated with ES.CONCLUSION: Both PSH-ES and recombinant ES effectively inhibit corneal NV induced by alkali burn.However, PSH-ES is a more powerful anti-angiogenic agent than ES. This research has the potential to provide a new treatment option for preventing and treating corneal NV.

Potential involvement of nitric oxide synthase but not inducible nitric oxide synthase in the development of experimental corneal neovascularization

AIM: To investigate the effect of nitric oxide and its synthetase on experimental corneal neovascularization (CRNV). METHODS: CRNV was induced by alkali injury in mice, nitric oxide synthetase (NOS) was inhibited by NG-nitro-L-arginine (L-NAME) and inducible nitric oxide synthetase (iNOS) was inhibited by aminoguanidine hemisulfate salt (AG). The inhibitory effect was detected at day 2 and 4 after corneal alkali injury by reverse transcription polymerase chain reaction (RT-PCR). CRNV was compared between the control and the treated mice by microscopic observation and corneal whole mount CD31 immunostaining. RESULTS: The inhibition of L-NAME to NOS and AG to iNOS after corneal injury was confirmed by RT-PCR (P <0.05). Compared with control mice, L-NAME treated mice exhibited significantly decreased CRNV areas (P<0.05). In contrast, AG treatment failed to attenuate alkali induced CRNV (P>0.05). CONCLUSION: Our findings suggest that NOS but not iNOS plays a critical role in alkali injury induced CRNV.

Effects of Interferon Alpha 2b on VEGFR-2, VEGFA, MAPK-1 and ERK-1 Gene Expression in Corneal Neovascularization Models

AIM: To investigate effects of interferon alpha 2b on vascular endothelial growth factor receptor-2 (VEGFR-2), vascular endothelial growth factor-A (VEGFA), mitogen activated protein kinase-1 (MAPK-1) and extracellular signal regulated kinase (ERK 1) gene expression in corneal neovascularization (CNV) modelsbyreal time polymerase chain reaction (PCR). METHODS: Thirty Wistar-Albino male rats were divided into three groups of ten rats each, and two corneas were obtained from each rat. CNV was induced by application of silver nitrate. In the first group one million IU/ml, in the second group three million IU/ml interferon-alfa 2b and in the third (control) group isotonic saline was applied to both eyes two times a day for two weeks. Rats were sacrificed by cervical dislocation and corneas were used for real time polymerase chain reaction. RESULTS: MAPK-1 gene expression levels were significantly higher in both first and second groups compared to the control group (p = 0.014 and p = 0.008, respectively). VEGFR-2 gene expression levels were found to be significantly higher in the second group than the control group (p = 0.028). VEGFA gene expression levels were also significantly higher in the second group than the control group, and there was no difference between the control and first group and between first and second groups (p > 0.05). ERK gene expression levels did not differ among all groups (p = 0.545). CONCLUSION: At the end of the study, it was shown that interferon-alfa 2b does not inhibit VEGFR-2, VEGFA, MAPK-1 or ERK 1 gene expression in CNV models despite its known anti-VEGF activities.

Sirolimus eye drops inhibit acute alkali-burn-induced corneal neovascularization by regulating VEGFR2 and caspase-3 expressions

Background:To investigate the effect of sirolimus(SRL)eye drops on acute alkali-burn-induced corneal neovascularization(CNV)and explore its possible mechanism.Methods:A total of 57 male Sprague-Dawley rats weighing 160-180 g were randomly divided into four groups including a normal control group(NC group,n=12),an untreated alkali-burned model control group(MC group,n=15),a blank eye drop treatment group(BT group,n=15),and an SRL eye drop treatment group(ST group,n=15).Corneal inflammation and CNV were observed and scored under a slit-lamp microscope 3,7,and 14 days after alkali exposure.Three rats were randomly sacrificed in each group before modeling and 3,7,14 days after modeling,and the corneas of right eyes were harvested for Western blotting to compare the expression levels of VEGFR2 and caspase-3.Results:Corneal inflammation scoring showed that the corneal edema and conjunctival congestion were severe in the MC,BT,and ST groups 1 day after alkali exposure but were alleviated at day 3.The corneal transparency was significantly higher in the ST group than in the MC and BT groups at days 7(F=9.77,P<0.05)and 14(F=5.81,P<0.05).At day 1,the corneal limbal vascular network was markedly filled.SNV was obvious at days 3,7,and 14.The new blood vessels were shorter and sparser in the ST group than in the MC and BT groups,and the CNV scores showed significant differences among these groups(day 3:F=8.60,P<0.05;day 7:F=11.40,P<0.05;and day 14:F=41.59,P<0.01).Western blotting showed that the expressions of VEGFR2 and caspase-3 were low before modeling and showed no significant difference among the different groups(F=0.52,P>0.05;F=0.98,P>0.05).The corneal expression of VEGFR2 became significantly higher in the MC and BT groups than in the ST group 3,7,and 14 days after alkali exposure,and there were significant differences in relative gray-scale values among these groups(day 3:F=32.16,P<0.01;day 7:F=85.96,P<0.01;day 14:F=57.68,P<0.01).The increase in the corneal expression of caspase-3 was significantly larger in the ST group than in the MC and BT groups at days 3,7,and 14,and there were significant differences in relative gray-scale values among groups(day 3:F=32.16,P<0.01;day 7:F=53.02,P<0.01;day 14:F=38.67,P<0.01).Conclusions:SRL eye drops can alleviate acute alkali-burn-induced corneal inflammation and inhibit alkali-burn-induced CNV in rat models.It can reduce VEGFR2 expression and increase caspase-3 expression in the corneal tissue,which may contribute to the inhibition of alkali-burn-induced CNV.