The effect of bevacizumab on corneal neovascularization in rabbits

The effects of subconjunctival bevacizumab, ranibizumab, and aflibercept on corneal neovascularization

PURPOSE

To investigate the effects of subconjunctival bevacizumab, ranibizumab, and aflibercept in an experimental corneal neovascularization model.

MATERIALS AND METHODS

The eyes of 24 rats were chemically cauterized and randomly divided into four groups: bevacizumab group (0.05 mL/1.25 mg bevacizumab), ranibizumab group (0.05 mL/0.5 mg ranibizumab), aflibercept group (0.05 mL/1.25 mg aflibercept), and control group (0.05 mL saline solution). Plasma vascular endothelial growth factor (VEGF) levels were among the major measurement outcomes to assess corneal neovascularization. The collected plasmas were analyzed using the SIGMA RAB0511 Rat VEGF Elisa kit. The PCR technique and VEGF amplification procedures were used for molecular analysis. Each cornea was removed and histologically examined on day 21. Corneal images were evaluated by image analyzer software.

RESULTS

In the post-injection period, the number of major corneal arteries decreased significantly in the injection groups when compared to the control group (p = 0.037), but no statistically significant differences were noted among the injection groups (p > 0.05). The aflibercept group had the lowest area of neovascularization. Immunohistochemical staining revealed substantially lower VEGF percentages in neovascularized arteries of the injection groups than the control group (p = 0.015). In TUNEL staining, the mean TUNEL value (number/1hpf) was substantially greater in the control group than in the injection groups, but the mean TUNEL values were similar between the injection groups (p = 0.019, p > 0.05, respectively). No statistically significant differences were observed between the groups in terms of corneal surface area with increased cellularity, edema, and inflammation (p = 0.263). The mean plasma VEGF concentration in the control group was statistically greater than those in the injection groups (p = 0.001).

CONCLUSION

Subconjunctival bevacizumab, ranibizumab, and aflibercept crossed the blood and seemed to be effective in inhibiting corneal neovascularization without causing epitheliopathy in an experimental rat model compared to the controls. However, no significant results were noted between these three anti-VEGF molecules.

Resolution of Refractory Corneal Neovascularization with Subconjunctival Bevacizumab

Corneal neovascularization (CNV) has a variety of causes and threatens corneal clarity, thus optimal visual acuity. Conventional medical management includes topical steroids and matrix metalloproteinase inhibitors like doxycycline. Anti-vascular endothelial growth factor (anti-VEGF) agents have demonstrated promise but remain off-label for this indication. However, these agents hold value in cases refractory to first-line medical management. We report the case of a 63-year-old woman who presented with ocular rosacea and CNV affecting vision, on a background of acne rosacea. She was initially treated with fluorometholone and doxycycline, yet continued to deteriorate. Eventually she received two 1.5-mg subconjunctival injections of bevacizumab 2 months apart. CNV completely resolved and results were maintained at 4-year follow-up. This case demonstrates that refractory CNV can be effectively treated with subconjunctival injection of anti-VEGF bevacizumab. The resolution of CNV was also maintained years after injection with minimal adjunctive therapy during this period, and to our knowledge there are no other studies reporting a follow-up period of 4 years after treatment. This is a pertinent case for other clinicians treating patients in a similar situation.

Inhibitory Effect of Topical Cartilage Acellular Matrix Suspension Treatment on Neovascularization in a Rabbit Corneal Model

BACKGROUND

The extracellular matrix (ECM) of articular cartilage has an inhibitory effect on vascularization, yet clinical utilization has been technically challenging. In this study, we aimed to fabricate a biologically functional ECM powder suspension from porcine articular cartilage that inhibits neovascularization (NV).

METHODS

The digested-cartilage acellular matrix (dg-CAM) was prepared by sequential processes of decellularization, enzymatic digestion and pulverization. Physicochemical properties of dg-CAM were compared with that of native cartilage tissue (NCT). Cellular interactions between human umbilical vein endothelial cells (HUVECs) and dg-CAM was evaluated with proliferation, migration and tube formation assays compared with that of type I collagen (COL) and bevacizumab, an anti-angiogenic drug. We then investigated the therapeutic potential of topical administration of dg-CAM suspension on the experimentally induced rabbit corneal NV model.

RESULTS

The dg-CAM released a significantly larger amount of soluble proteins than that of the NCT and showed an improved hydrophilic and dispersion properties. In contrast, the dg-CAM contained a large amount of collagen, glycosaminoglycans and anti-angiogenic molecules as much as the NCT. The inhibitory effect on NV of the dg-CAM was more prominent than that of COL and even comparable to that of bevacizumab in inhibiting the HUVECs. The therapeutic potential of the dg-CAM was comparable to that of bevacizumab in the rabbit corneal NV model by efficiently inhibiting neovessel formation of the injured cornea.

CONCLUSION

The current study developed a dg-CAM having anti-angiogenic properties, together with water-dispersible properties suitable for topical or minimally invasive application for prevention of vessel invasion.

Comparison of Topical Pigment Epithelium-Derived Factor (PEDF) with Topical Bevacizumab for Accelerating the Regression of Corneal Neovascularization in an Experimental Model of Rabbit Corneal Angiogenesis

Purpose: To evaluate the anti-angiogenic effect of topical administration of Pigment epithelium-derived factor (PEDF) on the reduction of corneal neovascularization (NV) in comparison to topical Bevacizumab.Methods: 18 eyes of 18 New Zealand rabbits were enrolled. Corneal NV was induced by a 7-0 silk suture. After suture removal, rabbits were randomly divided into three groups. In every group, one eye randomly treated with topical bevacizumab or topical PEDF or saline for 14 days. The area and length of neovascularization were measured by Image J. Histological studies were done in three groups.Results: After 14 days, the mean decrease of corneal NV length was 1.84 ± 0.17 mm (P < .001) in PEDF group and 1.6 ± 0.07 mm (P < .001) in bevacizumab group which was significantly more than the saline group (P = .001 and P < .001, respectively). There was no significant difference between PEDF and bevacizumab group in the reduction of corneal NV length (P = .85). The mean decrease of corneal NV area was 4.94 ± 0.55 mm² (P < .001) in PEDF group and 4.23 ± 0.29 mm² in the bevacizumab group (P < .001). PEDF and bevacizumab significantly decreased corneal NV area in comparison to the saline group (p = .017, p = .001, respectively). The mean decrease of corneal NV area did not show a significant difference between PEDF and bevacizumab groups (P = .72).Conclusion: Topical PEDF might be an effective and safe treatment option as bevacizumab in a short-term use, indicating that it is as good as the standard. However, long-term effect is required to be investigated.

Effects of Combined Photodynamic Therapy and Topical Bevacizumab Treatment on Corneal Neovascularization in Rabbits

PURPOSE

To evaluate the effects of combined photodynamic therapy (PDT) and topical bevacizumab treatment on corneal neovascularization in rabbits.

METHODS

Corneal neovascularization was induced by placing a suture for 7 days in both eyes of 15 rabbits. After suture removal, the right eyes of the rabbits were divided into 3 treatment groups (n = 5 each): group 1, 5 mg/mL bevacizumab eye drops; group 2, PDT at 150 J/cm; and group 3, combined PDT and topical bevacizumab treatment. All 15 left eyes formed a control group. After 2 weeks of treatment, digital photographs were obtained and analyzed to determine the area of corneal neovascularization. The rabbits were then killed to measure vascular endothelial growth factor (VEGF) levels in corneal tissues.

RESULTS

The corneal neovascularization area after treatment was significantly smaller in the 3 treatment groups compared with that in the control group. A significant difference was observed between groups 1 and 2 and group 3, but not between groups 1 and 2. VEGF levels were significantly lower in groups 1 and 3 than in the control group. Although group 2 exhibited relatively higher VEGF levels compared with the control group, the difference was not significant.

CONCLUSIONS

Our results suggest that combined PDT and topical bevacizumab treatment is significantly more effective than monotherapy for the treatment of corneal neovascularization in rabbits. Such quantitative comparison in the laboratory is believed to provide the theoretical basis for clinical application of combined PDT and topical bevacizumab treatment.

Chitosan-coated PLGA nanoparticles of bevacizumab as novel drug delivery to target retina: optimization, characterization, and in vitro toxicity evaluation

In several ocular diseases, the vascular endothelial growth factor (VEGF) level has been found to be upregulated. Bevacizumab, an anti-VEGF drug, is the most commonly used off level drug for these conditions. Delivery of drug to the posterior site is desired for the effective management of these diseases. The present study was to develop and optimize the chitosan (CS)-coated poly(lactide-co-glycolic acid) (PLGA) nanoparticles (NPs) of bevacizumab for sustained and effective delivery to posterior ocular tissues. NPs were prepared by double emulsion solvent evaporation method and optimized for various variables (i.e., CS concentration, PLGA content, polyvinyl alcohol (PVA) concentration, and sonication time) by employing a 4-factor 3-level Box-Behnken statistical design. NPs were characterized for particle size, polydispersity index (PDI), entrapment efficiency (EE), and in vitro release. Transscleral flux was determined through goat sclera, and ocular tolerance assay was done by Hen's Egg Test chorioallantoic membrane method. The particle size and PDI of the optimized NPs were 222.28 ± 7.45 nm and 0.19 ± 0.08, respectively. The developed NPs showed an EE of 69.26 ± 1.31% with an extended release profile. The flux was significantly higher that is, 0.3204 ± 0.026 μg/cm²/h for the NPs compared to drug solution. Thus, CS-coated PLGA NPs can be potentially useful as ocular drug carriers to target retina.

Inhibition of Pathologic Corneal Neovascularization by Topical Application of a Novel Peptide In Vivo

PURPOSE

To investigate the antiangiogenic effect of topical application of H-KI20, a novel 20-amino acid peptide from the hepatocyte growth factor, on 2 animal models of corneal neovascularization (NV), and its possible toxic effects on the cornea and conjunctiva.

METHODS

The antiangiogenic effect of topical H-KI20 in vivo was studied on corneal NV induced by a mouse corneal micropocket assay and rat intrastromal suture model. In each model, H-KI20, scrambled control peptide H-KI20S, bevacizumab, and phosphate buffer solution (PBS) were applied topically 4 times a day. Corneal NV was examined, photographed, and analyzed. Histological analysis of the corneas was performed. Tear film breakup time and gross and histological examinations were used to study the possible toxicity of topical H-KI20.

RESULTS

Topical application of H-KI20 significantly inhibited corneal NV induced by vascular endothelial growth factor (VEGF), and intrastromal suture (P < 0.01 vs. the PBS group), and the area of corneal NV was suppressed by 80.3% and 83.6%, respectively (PBS group as 100%). No significant difference was found between 1.0 mg/mL H-KI20 and 10 mg/mL bevacizumab (P > 0.05). Both hematoxylin and eosin and CD34 staining revealed fewer new blood vessels in the H-KI20 and bevacizumab groups. Tear film breakup time and histological examinations showed that H-KI20 had no obvious toxic effects on the cornea and conjunctiva in vivo.

CONCLUSIONS

The novel peptide H-KI20 is an effective and safe inhibitor of corneal NV. It may provide a promising alternative for ocular topical antiangiogenic therapy.

Inhibitory Effect of Topical Aflibercept on Corneal Neovascularization in Rabbits

PURPOSE

To examine the inhibitory effect of topical aflibercept [vascular endothelial growth factor (VEGF) trapR1R2] on corneal neovascularization (NV) in rabbits.

METHODS

Corneal NV was induced in 24 eyes of 12 rabbits. Seven days after a silk suture in the corneal stroma, the rabbits were divided into 4 groups of 6 eyes each. Two groups were treated with topical aflibercept at 2 different concentrations: 2 mg/0.5 mL (0.1%, group 1) and 2 mg/5 mL (0.01%, group 2). The other 2 groups were treated with topical bevacizumab 2.5 mg/1 mL (0.1%, group 3) and topical balanced salt solution (group 4, control). The concentration of VEGF and placental growth factor (PIGF) messenger RNA (mRNA) was measured by reverse transcriptase-polymerase chain reaction.

RESULTS

The surface area of NV was significantly smaller in the treatment groups compared with that of the control group. The expression of VEGF mRNA was 0.227 in 0.1% aflibercept (group 1), 0.811 in 0.01% aflibercept (group 2), and 0.495 in 0.1% bevacizumab (group 3). There was a significant decrease in the VEGF concentration in all 3 treatment groups compared with the control group, 1.491 (P = 0.031, <0.05). In the 0.01% aflibercept group, the difference was less than that of the 0.1% aflibercept and 0.1% bevacizumab groups. There was no significant difference in the 0.1% aflibercept and 0.1% bevacizumab groups. The expression of PIGF mRNA was 0.791 in 0.1% aflibercept (group 1), 0.743 in 0.01% aflibercept (group 2), 1.194 in 0.1% bevacizumab (group 3), and 1.458 in the control group. The expression of PIGF mRNA was significantly decreased in the 0.1% aflibercept and 0.01% aflibercept groups.

CONCLUSIONS

Topical aflibercept may have an inhibitory effect on corneal NV in rabbits.

Effects of subconjunctival tocilizumab versus bevacizumab in treatment of corneal neovascularization in rabbits

PURPOSE

The aim of this study was to compare the antiangiogenic effects of subconjunctival application of bevacizumab and tocilizumab on the regression of corneal neovascularization (NV) in rabbits.

METHODS

Corneal neovascularization was induced in 48 eyes of 24 rabbits. Seven days after suture placement, the rabbits were divided into 4 groups of 6 rabbits each and treated subconjunctivally with 0.1 mL balanced salt solution (group 1), 0.1 mL tocilizumab (0.25 mg per 0.1 mL and 2.5 mg per 0.1 mL, groups 2 and 3), or 0.1 mL bevacizumab (2.5 mg per 0.1 mL) (group 4). Digital photographs of the eyes were obtained and the surface areas of corneal neovascularization were measured on days 7 and 14 after subconjunctival injections. On days 7 and 14, 3 rabbits were randomly chosen and the eyes were extracted. Half of the corneal specimens were analyzed histopathologically, and the other half were used to measure the concentrations of vascular endothelial growth factor (VEGF) and IL-6 using a multiplex bead assay, and the levels were compared with those of the controls.

RESULTS

The surface areas of induced corneal neovascularization were significantly smaller in groups 3 and 4 (2.5 mg of tocilizumab and 2.5 mg of bevacizumab) compared with the control group on days 7 and 14 (P < 0.05). Group 2 did not show significant difference from the control group on days 7 and 14. There were no differences observed in the reduced neovascularization areas in groups 3 and 4 on days 7 and 14. The concentrations of VEGF in groups 3 and 4 were significantly lower than in the control group, and IL-6 mRNA levels were significantly lower in group 3 than in the other groups (P < 0.001) on days 7 and 14. Immunohistochemical analysis confirmed the reduced expression of VEGF in all 3 experimental groups compared with the control group.

CONCLUSIONS

An antiangiogenic effect was observed after subconjunctival injection of 2.5 mg tocilizumab to an extent similar to that seen with 2.5 mg bevacizumab, which indicates that subconjunctival application of tocilizumab is effective for the inhibition of corneal neovascularization.

Ocular delivery of macromolecules

Biopharmaceuticals are making increasing impact on medicine, including treatment of indications in the eye. Macromolecular drugs are typically given by physician-administered invasive delivery methods, because non-invasive ocular delivery methods, such as eye drops, and systemic delivery, have low bioavailability and/or poor ocular targeting. There is a need to improve delivery of biopharmaceuticals to enable less-invasive delivery routes, less-frequent dosing through controlled-release drug delivery and improved drug targeting within the eye to increase efficacy and reduce side effects. This review discusses the barriers to drug delivery via various ophthalmic routes of administration in the context of macromolecule delivery and discusses efforts to develop controlled-release systems for delivery of biopharmaceuticals to the eye. The growing number of macromolecular therapies in the eye needs improved drug delivery methods that increase drug efficacy, safety and patient compliance.

Comparative study of ranibizumab and bevacizumab on corneal neovascularization in rabbits

PURPOSE

The aim was to compare the effect of subconjunctival injections of ranibizumab and bevacizumab on corneal neovascularization (NV) in rabbits.

METHODS

NV was induced by placing a suture at the corneal periphery of rabbits (n = 30 eyes). Immediately after suturing, the rabbits were divided into 3 groups and 7 days later administered subconjunctival injections of ranibizumab (Lucentis; 0.5 mg/0.05 mL), bevacizumab (Avastin; 5 mg/0.05 mL), or normal saline (control), respectively. The time-course photographs to measure the area of the corneal NV were obtained on days 7, 10, and 14 after suture placement. Histological examination and immunohistochemical analysis for the vascular endothelial growth factor and CD34 were performed.

RESULTS

Analysis of digital photographs showed that there was less corneal NV in the ranibizumab- and bevacizumab-treated eyes than in the control eyes (P = 0.012, 1-way analysis of variance); however, no significant differences between the ranibizumab- and bevacizumab-treated eyes were seen. In addition, there was less staining for vascular endothelial growth factor and CD34 in the corneas from the ranibizumab-treated eyes and bevacizumab-treated eyes than in the control eyes, and there were no significant differences in the staining intensity between the ranibizumab- and bevacizumab-treated eyes. Subconjunctival ranibizumab and bevacizumab injections were not associated with any complications during observations.

CONCLUSIONS

Subconjunctival administrations of ranibizumab or bevacizumab inhibit corneal NV in rabbits and have equivalent effects on it.

The effect of subconjunctival ranibizumab on corneal and anterior segment neovascularization: study on an animal model

PURPOSE

To evaluate the effect of subconjunctival anti-vascular endothelial growth factor (VEGF) ranibizumab on corneal and anterior segment neovascularization.

METHODS

In this experimental study and laboratory investigation, chemical cauterization was utilized to induce corneal neovascularization in 16 rabbits randomly divided in 2 equal groups. Cauterized eyes were either treated with 0.1 mL (1 mg) of subconjunctival ranibizumab or administered a sham injection. A third group of 4 rabbits served as control for side effects after ranibizumab administration. All animals were monitored daily for 14 days and the extent of corneal scarring and neovascularization was measured on days 1, 7, and 14. After enucleation, ocular tissues were separated under a surgical microscope and VEGF levels were measured with ELISA. Statistical analysis was performed to compare the extent of corneal neovascularization and VEGF levels between treated and untreated eyes.

RESULTS

Subconjunctival ranibizumab inhibited corneal neovascularization significantly both in the first and the second week compared to untreated controls (p = 0.006 and p = 0.001, respectively). The VEGF levels were significantly lower in all anterior segment tissues like the cornea, iris, aqueous humor, and conjunctiva of the treated eyes (p<0.01). The reduction of VEGF levels ranged from 19% to 73% in different ocular tissues. Corneal scarring was not significantly affected by anti-VEGF treatment (p = 0.7). No side effects were noticed.

CONCLUSIONS

Early subconjunctival administration of ranibizumab may successfully inhibit alkali-induced corneal neovascularization in an animal model. Subconjunctival ranibizumab reduces VEGF levels significantly not only in the cornea and the bulbar conjunctiva but also in the aqueous humor and the iris.

Topically administered bevacizumab had longer standing anti-angiogenic effect than subconjunctivally injected bevacizumab in rat corneal neovacularization

AIM

To compare the effect of topically administered and subconjunctivally injected bevacizumab on experimental corneal neovascularization in rats for two weeks after treatment.

METHODS

Twenty-eight Sprague-Dawley rats were divided into four groups of 7 animals. Each corneal center of right eye was cauterized with silver/potassium nitrate for 8s. After corneal burning, bevacizumab (12.5mg/mL) was topically administered three times per day (TB group) for two weeks or subconjunctivally injected on days 2 and 4 after cauterization (0.02mL; SB group). As negative controls, rats received 0.9% saline topically three times per day (TS group) or subconjunctivally on days 2 and 4 (0.02mL; SS group). Digital photographs of the cornea were taken 1 and 2 weeks after treatment and analyzed to determine the area of cornea covered by neovascularization as the percentage of corneal neovascularization.

RESULTS

One week after treatment, the percentage of corneal neovascularization was significantly lower in the TB and SB groups than in the TS and SS groups (all P<0.05). Two weeks after treatment, the percentage of corneal neovascularization was significantly lower in the TB group than in the TS group (P<0.05). In all groups, the percentage of neovascularization was decreasing as time passed (all P<0.05).

CONCLUSION

Topically administered bevacizumab has longer standing anti-angiogenic effect than subconjunctivally injected bevacizumab in corneal neovascularization following chemical injury in rats.

The effect of antivascular endothelial growth factor on the development of adhesion formation in laparotomized rats: experimental study

Aims. This study determined the effects of a single dose of bevacizumab, an antiangiogenic recombinant monoclonal antibody that specifically targets vascular endothelial growth factor (VEGF), on adhesion formation in the rat cecal abrasion model. Methodology. Thirty female Wistar albino rats (200-224 g) were divided into three groups. All rats underwent laparotomy at which time cecal wall abrasion and abdominal wall injuries were induced. Group I (control) underwent only the abrasion procedure; Groups II and III received saline or bevacizumab intraperitoneally, respectively, following the abrasion. The rats were killed on postoperative day 7, and the severity of adhesions was evaluated, together with histopathological fibrosis parameters and immunohistochemical staining to identify the VEGF receptor. Results. The mean adhesion severity score in Groups I-III was 2.5 ± 0.52, 2.4 ± 0.69, and 0.7 ± 0.82, respectively; the score in Group III was significantly lower than that in Groups I (P < 0.001) and II (P < 0.001). In the histopathological evaluation, the mean fibrosis score in Group III was significantly lower that the scores in Groups I (P < 0.001) and II (P < 0.001). VEGF staining of the adhesion areas in Group III was significantly lower than that in Groups I (P < 0.001) and II (P < 0.001). Conclusion. Bevacizumab decreases adhesion formation following laparotomy in rats by blocking VEGF receptor occupancy.