Photodynamic therapy for corneal neovascularization using topically administered ATX-S10 (Na)

BACKGROUND AND OBJECTIVE: We investigated the effect of photodynamic therapy (PDT) using topically administered ATX-S10(Na) on corneal neovascularization (CoNV). MATERIAL AND METHODS: Rabbit eyes with induced CoNV were treated with ATX-S10(Na) eye drops (10 mg/mL) every 5 minutes, 5 to 25 times. Five to ninety minutes after topical administration, the CoNV were irradiated with a diode laser using a wavelength of 670 nm. RESULTS: The CoNV were occluded fluorescein angiographically in 7 of 16 treated eyes. The eyes having occluded, CoNV were irradiated using fluence of 510-1019 J/cm2 within 20 minutes of eye-drop administration. However, the effect was more variable than what we found using systemic administration in our previous investigation. CONCLUSIONS: Experimental CoNV was occluded by photodynamic therapy using topically administered ATX-S100(Na), suggesting this modality as a possible treatment for CoNV avoids the side effects found with systemic administration of the dye. Further efforts to improve the eye drops in terms of pH and osmotic pressure are needed to achieve increased dye accumulation.     

Treatment parameters for selective occlusion of experimental corneal neovascularization by photodynamic therapy using a water soluble photosensitizer, ATX-S10(Na)

Time dependent change of an accumulation of an amphiphilic photosensitizer, ATX-S10(Na) on rabbit corneal neovascularization (CoNV) was evaluated by angiography using ATX-S10(Na) as a fluorescent dye on three rabbits. The angiography showed that the dye accumulated on CoNV 3-5 hr after dye injection when the dye in the iris was minimum. The results suggested 3-5 hr after might be the optimal time to start photodynamic therapy (PDT) to occlude CoNV selectively without damage to the surrounding normal tissue such as the iris. Then the optimal treatment parameters in PDT using ATX-S10(Na) for selective occlusion of the CoNV were investigated on rabbit eyes. PDT was performed with two different time intervals between dye injection and laser irradiation of a diode laser (670 nm), different laser doses and three different dye doses on 21 animals. PDT performed immediately after dye injection selectively occluded CoNV with laser irradiations from 30.6 to 38.2 J cm(-2)and a 2 mg kg(-1)dose of ATX-S10(Na), as well as with 15.3 J cm(-2)and a 6 mg kg(-1)dose. PDT performed 4 hr after dye injection with 107.0-152.8 J cm(-2)and a 6 mg kg(-1)dose, as well as with 38.2-53.5 J cm(-2)and a 12 mg kg(-1)dose was also effective. Although PDT performed either immediately or 4 hr after ATX-S10(Na) injection selectively occluded CoNV, the width of the optimal range of radiant exposures seemed wider in PDT performed 4 hr after dye injection. It is supposed that this result is associated with the difference of dye accumulation between in CoNV and in normal tissue as shown by the present angiographical findings.     

Effect of photodynamic therapy with ATX-S 10 (Na) on experimental choroidal neovascularization

PURPOSE: To evaluate an appropriate irradiative condition for selective occlusion of experimental choroidal neovascularization(CNV) with photodynamic therapy (PDT) using ATX-S 10 (Na). METHODS: Experimental CNV was induced in monkey eyes by laser photocoagulation. PDT(dose of irradiative energy 40 to 80J/cm2) was performed after 3.5 mg/kg of body weight intravenous injections of ATX-S 10(Na). CNV and retinal vessel occlusion induced by PDT was evaluated by fluorescein angiography (FA) at 1 and 7 days after irradiation. If FA showed no fluorescein dye leakage from CNV at 1 and 7 days after irradiation, CNV was evaluated by histopathological analysis at 7 days after irradiation. RESULTS: Within 30 to 33 minutes after ATX-S 10(Na) injection and irradiation with 50 to 60 J/ cm2, FA showed no fluorescein dye leakage from CNV and no closure of retinal vessels at 1 and 7 days after irradiation. Light micrographs showed occluded CNV, and retinal vessels remained patent and there was no apparent change in the inner layer of the retina. CONCLUSIONS: Irradiative condition of ATX-S10 (Na) 3.5 mg/kg was appropriate 30 to 33 minutes after ATX-S 10(Na) injection and irradiation with 50 to 60 J/cm2.     

外源性小鼠干扰素诱导蛋白-10抑制实验性角膜新生血管的作用机制

背景 干扰素诱导蛋白-10(IP-10)作为趋化因子调节免疫炎症反应方面的作用已被证实,但最近的研究发现其在抑制新生血管生成方面发挥一定的作用.角膜新生血管(CNV)的形成与多种血管新生相关因子有关,IP-10对CNV形成的作用及机制尚不明确. 目的 探讨外源性小鼠IP-10点眼对角膜碱烧伤诱导CNV形成的作用.方法 选用SPF级BALB/c小鼠82只,并按随机数字表法分组.采用浸润1 mol/LNaOH的滤纸贴附于左眼角膜中央40 s的方法制作角膜碱烧伤小鼠模型,角膜碱烧伤后1d及7d开始局部应用IP-10共7d分别作早期点眼组10只眼和中晚期点眼组5只眼,各自的模型对照组均给予质量分数0.2％透明质酸钠(HA)点眼(分别为11只眼和6只眼).早期点眼组于造模后2周,中晚期点眼组于造模后3周取角膜组织以CD31免疫荧光标记法比较模型对照组及实验组的CNV面积.收集早期IP-10碱烧伤后2d及4d小鼠的角膜组织,用逆转录聚合酶链反应(RT-PCR)法检测并比较各组小鼠角膜组织中趋化因子受体3(CXCR3)、血管内皮生长因子(VEGF)及转化生长因子β1(TGF-β1)mRNA的表达情况.所有实验动物的使用、饲养及处死均按照视觉及眼科学研究协会的有关规定及苏州大学的《实验动物管理及使用指南》进行.结果 模型对照组小鼠CNV占角膜面积的比例为(88.67±10.22)％,IP-10早期点眼1周组小鼠CNV占角膜面积的(70.06±12.21)％,差异有统计学意义(t=3.77,P=0.00).角膜碱烧伤后21 d,模型对照组小鼠CNV占角膜面积的比例为(87.33±13.47)％,IP-10中晚期点眼1周组CNV占角膜面积的(86.56±12.47)％,差异无统计学意义(t=1.260,P＞0.05).IP-10早期点眼2d和4d的小鼠角膜组织中CXCR3的表达较模型对照组同期值明显升高(t=3.13、3.07,P＜0.05)、VEGF表达降低(t=5.99、6.27,P＜0.01)、TGF-β1表达降低(t=8.50,P＜0.01;t=4.53,P＜0.05).结论 角膜碱烧伤后外源性IP-10蛋白早期干预可通过上调CXCR3和下调VEGF及TGF-β1的表达抑制CNV的形成,中晚期干预不能减少角膜碱烧伤诱导的CNV.     

Effect of subconjunctival bevacizumab (Avastin) on experimental corneal neovascularization in guinea pigs

PURPOSE: To evaluate the effect of subconjunctival bevacizumab (Avastin) on experimental corneal neovascularization in guinea pigs. METHODS: Forty eyes of 40 guinea pigs were chemically cauterized with 75% silver nitrate and 25% potassium nitrate sticks. Fifteen eyes (group 1) received 2 subconjunctival injections of bevacizumab (0.1 mL, 1.25 mg) simultaneously with cauterization and 3 days later. Fifteen eyes (group 2) received 2 subconjunctival injections of bevacizumab (0.1 mL, 1.25 mg) 3 and 5 days after cauterization. Ten eyes (group 3, control group) received 2 subconjunctival injections of 0.1 mL of balanced salt solution 3 and 5 days after cauterization. After we determined the burn and neovascularization scores for all groups, the animals were killed on the 10th day. The percentages of neovascularization on the surface of the cornea were measured in terms of pixels on digital photographs. The average number of vessels at maximally vascularized areas was determined for each specimen. RESULTS: Neovascularization score was 1.1 +/- 0.3 in group 1, 2.46 +/- 1.3 in group 2, and 3.5 +/- 0.5 in the control group. The difference was statistically significant (P < 0.001). The area of neovascularization at the cornea surface was 15.6% +/- 10.1% in group 1, 19.74% +/- 11.2% in group 2, and 23.5% +/- 7.4% in the control group (P = 0.194). The average number of neovascular vessels at group 1 was significantly reduced in comparison with group 2 and the control group (P < 0.001). CONCLUSIONS: Subconjunctival injection of bevacizumab decreases the extent of chemically induced corneal neovascularization in guinea pigs. The antineovascular effect of bevacizumab is higher if the injection is performed simultaneously with the chemical cauterization.     

实验性角膜新生血管形成的形态学研究

采用氢氧化钠灼伤角膜方法，诱导２０只兔眼角膜新生血管形成，并对其发生、发展过程进行裂隙灯显微镜、光镜和透射电镜观察。结果发现，伤后８小时，角膜缘组织已有中性粒细胞浸润等明显急性炎症变化；渗出于血管外的中性粒细胞胞质内吞噬溶酶体异常丰富。在伤后２天，角膜缘才出现新生血管芽，角膜新生血管周围可见中性粒细胞浸润及其崩解产物。提示白细胞，特别是中性粒细胞，参与角膜新生血管形成过程，并可能起介导作用。     

Inhibition of experimental corneal neovascularization by using subconjunctival injection of bevacizumab (Avastin)

PURPOSE: To evaluate the effect of subconjunctival bevacizumab (Avastin) administration on corneal neovascularization (NV) in rabbits. METHODS: NV was induced by placing a suture at the corneal periphery of the right eye of 20 rabbits. Immediately after suturing and again 1 week later, rabbits were divided into 2 groups and administered a subconjunctival injection of normal saline (control) or bevacizumab (Avastin; 5 mg/0.2 mL), respectively. On day 14, digital photographs of the cornea were taken and analyzed to determine the area of the cornea covered by NV. In addition, immunohistochemical analysis was used to determine CD31 and vascular endothelial growth factor (VEGF) expression in corneal tissue. RESULTS: Analysis of digital photographs showed that there was less corneal NV in bevacizumab-treated eyes than in controls (P < 0.001, Mann-Whitney U test). In addition, there was less staining for VEGF and CD31 in corneas from bevacizumab-treated eyes than in control eyes. Subconjunctival bevacizumab injections were not associated with any complications during observation. CONCLUSIONS: Subconjunctival bevacizumab administration decreased suture-induced corneal neovascularization in rabbits.     

PDT to monkey CNV with ATX-S10(Na): inappropriateness of early laser irradiation for selective occlusion

PURPOSE: There is controversy about which mode of laser irradiation, early irradiation with low-dose photosensitizer or late irradiation with high-dose, benefits the selective occlusion of choroidal neovascularization (CNV) in photodynamic therapy (PDT). In this study, using an amphiphilic photosensitizer, 13,17-bis (1-carboxypropionyl) carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyiminoethylidene-2,7,12,18-tetraethyl porphyrin sodium (ATX-S10(Na); Photochemical Inc., Okayama, Japan), photodynamic and adverse effects of early irradiation on CNV-bearing monkey eyes were investigated. METHODS: Experimentally induced CNV lesions and normal retina were irradiated with a diode laser (670-nm wavelength) at a dose of 1 to 90 J/cm(2) at 1 to 19 minutes after intravenous injection of 2 mg/kg body weight of ATX-S10(Na). Vascular occlusion and CNV recurrence were evaluated by fluorescein and indocyanine green angiography and histologic analysis, until 4 weeks after irradiation. RESULTS: Of 45 different conditions, 23 did not induce CNV closure, 20 provided both CNV occlusion and retinal vessel damage, and 2 achieved selective CNV occlusion without retinal vascular injury. Recurrence of CNV was induced in 19 of 22 CNV-occluding conditions. ATX-S10(Na) angiography showed that dyes were similarly distributed between normal vessels and CNV at early time periods after injection, whereas they were preferentially accumulated in CNV after 30 minutes. CONCLUSIONS: In PDT with ATX-S10(Na), irradiation within 20 minutes of dye injection failed to induce selective CNV occlusion, probably because there is no significant difference in the biodistribution of dye between CNV and retinal vessels. It also caused frequent CNV recurrence after extensive inflammation in the irradiated retina.     

实验性角膜新生血管的形态观察

目的观察兔角膜新生血管的形态特点,探讨其发生机制及治疗效果.方法将16只新西兰兔随机分为实验和对照两组,均以75%硝酸银液烧灼兔角膜,实验组于硝酸银烧灼后行β射线照射,观察两组角膜新生血管的生长规律;选期制做新生血管铸型,扫描电镜下比较两组间新生血管形态差异.结果角膜新生血管以典型的芽生方式发生和增殖,经β射线照射后的血管芽形成受到明显的抑制和破坏,新生的血管支干发生萎缩、坏死.结论阻断新生血管的芽生过程可抑制角膜新生血管的形成和发展.     

Effect of Octreotide on experimental corneal neovascularization.

PURPOSE: To examine the ability of subcutaneously administered Octreotide ( a long acting somatostatin analoque) to serve as an inhibitory agent for corneal neovascularization in eyes of Wistar Albino rats. METHODS: Neovascular growth into the corneas of all the animals was induced by silver nitrate cauterization. Half of the animals which were randomly selected for the Octreotide group received 30 micrograms systemic Octreotide for 7 days. The treatment was initiated on the same day as chemical cauterization. The rest of the animals (control group) received no treatment. Slit lamp and histopathologic examination of the corneas of both groups were performed at the end of the study period. RESULTS: It was observed that the corneal neovascularization and histopatologic scores of the Octreotide group were significantly lower than those of the control group (p < 0.001, p < 0.01). CONCLUSION: Systemic administration of Octreotide inhibits the corneal neovascular response in a rat model.     

Langerhans cells and corneal neovascularization in experimental alkali burns

Experimental alkali-burns rabbit corneas present a neovascularisation. Six weeks later the corneas have been processed for ATPase Cytochemistry, allowing the observation of Langerhans cells. We observed an increase in the number of Langerhans cells that was statistically significant in alkali-burned corneas when compared to unburned corneas in the peripheral and midperipheral cornea.     

Effect of bevacizumab on corneal neovascularization in experimental rabbit model

Purpose:  To investigate the effect of bevacizumab in an experimental rabbit model of corneal neovascularization.
Methods:  The right eyes of 24 white New Zealand rabbits were included in a corneal neovascularization model using alkaline burn. They were divided into four groups. Topical bevacizumab was installed three times daily in group 1, 5 mg bevacizumab subconjunctivally every 2 days in group 2, 10 mg bevacizumab subconjunctivally every 2 days in group 3 and 0.2 cc of normal saline in the same way in group 4 (control group). All eyes were treated for 7 days. Then the animals were killed and corneal specimens sent for histopathological analysis. Tear film and aqueous humour samples were obtained to assess vascular endothelial growth factor (VEGF) levels.
Results:  Seven days after topical bevacizumab treatment the neovascular index in group 1 was lower than that in the control group ( P  = 0.028). In groups 2 and 3 the neovascular index was lower 2 days after subconjunctival bevacizumab treatment than that in control group ( P  = 0.009 and P  = 0.009, respectively). In the control group the VEGF level in aqueous humour increased by 66% from day 7 to 14. In groups 1–3 it decreased by 49.80%, 70.20% and 76.44%, respectively ( P  = 0.043). The VEGF level in tear film of the control group increased by 35.23% from day 7 to 14, which was not significant ( P  = 0.893), while in groups 1–3 it decreased by 57.26%, 34.59% and 67.97%, respectively, which was only significant in groups 1 and 3 ( P  = 0.043).
Conclusions:  Subconjunctival 5 mg/mL bevacizumab is effective in reducing corneal neovascularization in animal models and in reducing VEGF levels. Further research is needed to assess the potential side effects and minimal effective dose.     

Anti-apoptosis effects of vascular endothelial cadherin in experimental corneal neovascularization

AIM: To explore the effects and mechanism of vascular endothelial cadherin (VE-cadherin) on experimental corneal neovascularization (CRNV). METHODS: Mouse corneas were burned with sodium hydroxide to build a CRNV model. The burned corneas were locally administrated with anti-mouse VE-cadherin neutralizing antibody. Annexin V and cluster of differentiation 31 (CD31) double staining was used to measure vascular endothelial cell apoptosis with the use of flow cytometry (FCM). The protein expression of NADPH oxidase 2 (Nox2), caspase-3, and protein kinase C (PKC) in the burned corneas were examined by Western blot. Human retinal endothelial cell (HREC) proliferation was detected using a Cell Counting Kit 8 (CCK-8) assay in vitro. RESULTS: The amount of CRNV peaked two weeks after the alkali burn. FCM confirmed that VE-cadherin neutralizing antibody treatment increased CD31 positive cell apoptosis. Western blot revealed that the intracorneal protein expression of Nox2 and caspase-3 were up-regulated, while PKC was down-regulated in the VE-cadherin neutralizing antibody administrated group. CCK-8 assay showed that VE-cadherin neutralizing antibody markedly inhibited HREC proliferation. CONCLUSION: VE-cadherin exhibited an anti-apoptosis effect through enhanced PKC signaling and an enhanced cell proliferation pathway.     

贝伐单抗抑制角膜新生血管的实验研究

目的评价贝伐单抗（avastin）局部应用对小鼠角膜新生血管（CNV）的抑制作用。方法通过碱烧伤建立CNV模型,将30只Balb／c小鼠随机分成5组,A组贝伐单抗1mg／mL每日点眼2次;B组贝伐单抗3mg／mL每日点眼2次;C组贝伐单抗5mg／mL每日点眼2次;D组0．1％地塞米松每日点眼2次;E组生理盐水每日点眼2次。分别于术后3、7、14d观察CNV情况并拍照。术后第14天,处死全部小鼠,行CNV内皮细胞荧光标记,计算CNV所占全角膜面积的比例。结果各组CNV面积为A组（37．11±3．17）％、B组（29．75±3．56）％、C组（18．76±2．55）％、D组（20．91±2．75）％,E组（41．65±2．11）％。各组小鼠CNV面积依次为c组〈D组〈B组〈A组〈E组,C组同A、B、E组比较差异均有统计学意义（P〈0．01）,c组与D组比较差异无统计学意义（P=0．694）。结论局部应用贝伐单抗对小鼠角膜化学烧伤后的CNV有抑制作用。     

大鼠角膜化学伤后PEDF和VEGF的不平衡表达

目的比较硝酸银化学伤后大鼠角膜和正常角膜色素上皮衍生因子（PEDF）和血管内皮生长因子（VEGF）表达水平，揭示两者与角膜新生血管的相关性。方法10只大鼠左眼角膜硝酸银化学伤后为实验组，右眼为正常对照组，伤后15d行免疫组织化学法定位及Western blot定量检测样本角膜PEDF、VEGF等的表达。结果免疫组织化学检查：实验组角膜VEGF、碱性成纤维细胞生长因子（bFGF）强表达，PEDF未见表达或弱表达。正常组角膜PEDF高表达，VEGF弱表达，bFGF几乎不表达。Western Blot分析：实验组角膜PEDF表达明显下降（t=8．0049，P〈0．01），VEGF表达显著升高（t=48．3637，P〈0．01）。结论角膜严重化学伤后新生血管抑制因子PEDF破坏，刺激因子VEGF产生增加，PEDF／VEGF比值降低，角膜血管新生。     

DATS对缝线诱导的大鼠角膜新生血管的影响及机制研究

目的：探讨二烯丙基三硫化物(diallyl trisulfide,DATS)抑制缝线诱导的大鼠角膜新生血管(corneal neovascularization,CNV)的生长情况,检测大鼠新生血管化角膜中VEGF、p-AKT 的表达量,初步探讨其抑制CNV的可能机制。

方法：缝线法诱导大鼠CNV模型,随机分为A组：含DMSO的生理盐水对照组(10只); B组：25μmol/L DATS治疗组(10只); C组：50μmol/L DATS治疗组(10只); D组：100μmol/L DATS治疗组(10只); E组：200μmol/L DATS治疗组(10只)。缝线后第7d裂隙灯下观察各组CNV的生长情况并计算面积。缝线后第14d取各组大鼠角膜组织行HE 染色,光镜下观察各组角膜病理组织形态,并采用RT-PCR 法检测VEGF mRNA 的表达情况,Western-blot 法检测VEGF、p-AKT蛋白表达情况。

结果：C、D、E组的CNV面积分别与A组比较,差异均有统计学意义(P<0.05)。HE切片显示,与A组相比,B、C、D组角膜水肿、新生血管、炎症细胞浸润情况逐渐减轻。与A组相比,B、C、D、E组的VEGF mRNA 的表达水平均降低,差异均有统计学意义(P<0.05)。与A组相比,C、D、E组的VEGF、p-AKT蛋白的表达逐渐下降,差异均有统计学意义(P<0.05)。

结论：DATS 能够抑制缝线诱导的大鼠CNV的形成,其机制可能与抑制VEGF的表达及使得p-AKT的失活有关。     

Bevacizumab (Avastin) eye drops inhibit corneal neovascularization

Background To analyze the ability of bevacizumab (Avastin) eye drops to inhibit corneal neovascularization. Design: interventional case series involving five patients (age: 42 ± 14 years). Methods Patients with aggressive corneal neovascularisation not responding to conventional therapy were treated with bevacizumab (Avastin) eye drops (5x/day; 5 mg/ml) for 0.5 to 6 months (mean: 3.6 ± 2; four patients with limbal stem cell deficiency [three due to chemical burns and one inherited] and one after perforating keratoplasty). Results Bevacizumab eye drops were well tolerated without obvious corneal side-effects. All five patients showed a reduction in the neovascularized area (decrease 48 ± 28%; 13–75%). Conclusions Bevacizumab eye drops seem to inhibit corneal neovascularization without obvious corneal epithelial side-effects.     

Bevacizumab (Avastin)抑制角膜新生血管的应用新进展

诱发角膜新生血管的因素涉及各种生长因子。研究表明:在角膜新生血管中广泛存在的血管内皮生长因子(vascular endothelial growth factor,VEGF)起着主要作用。一种可行的治疗角膜新生血管策略是:通过特异性的中和抗VEGF抗体竞争性的结合VEGF,从而抑制VEGF活性。近年来,利用抗VEGF治疗策略,抑制脉络膜新生血管获得了很好的效果。靶向VEGF治疗药物的疗效和安全性已经证明。因此我们设想,局部应用新的抗VEGF药物,如贝伐单抗、兰尼单抗等可以有效地抑制角膜新生血管,恢复角膜透明和视力。     

金雀异黄素对兔角膜碱烧伤新生血管的抑制作用

目的:探讨金雀异黄素(genistein,Gen)对兔角膜新生血管(corneal neovascularization,CNV)的抑制作用。方法:取新西兰大白兔13只,不造模1只观察药物对眼表前房等组织的不良反应。其余12只24眼采用浸润1mol/LNaOH滤纸片贴敷角膜中心60s,诱导碱烧伤CNV形成,左眼用二甲亚砜(dimethylsulfoxide,DMSO)溶液,右眼用Gen的DMSO溶液点眼。碱烧伤后3,7,14,21d测量角膜CNV面积,处死相应组别的动物取眼球做切片HE染色和免疫组织化学染色观察角膜和前房等情况。结果:兔角膜碱烧伤后CNV存在生长和消退的病理变化,Gen+DMSO组角膜CNV面积与DMSO组相比有明显的统计学差异性(P<0.01)。结论:Gen对于兔角膜碱烧伤模型的CNV有明显的抑制作用。