The heparan sulfate suleparoide inhibits rat corneal angiogenesis and in vitro neovascularization

Comparison of the effect of topical bevacizumab and sorafenib in experimental corneal neovascularization

PURPOSE

The purpose of this study was to compare the neovascularization inhibiting the effect of topical bevacizumab and sorafenib and to determine the effective dose of sorafenib.

MATERIAL AND METHODS

Forty-two healthy Wistar albino rats were randomly divided into six groups. The right corneas of all rats except group 1 were cauterised with silver nitrate. Group 2 received DMSO, group 3 received topical bevacizumab (5 mg/dL, 3 times a day) and group 4, 5 and 6 received topical sorafenib (2.5 mg/dl, 5 mg/dL, 7.5 mg/dL, 2 times a day respectively), between days 1 and 7. Corneal photographs were taken on day 8 and the corneal neovascular area percentage was calculated. Following decapitation, the corneas were removed to determine the levels of VEGF ELİSA and corneal immune staining. The Mann-Whitney U-test was used for statistical analysis.

RESULTS

The neovascular corneal area percentage was statistically significantly lower in the treatment groups than group 2 (p < 0.05). The intensity of VEGF immune staining was also lower in groups 3, 5 and 6 from the group 2. Group 3, 5 and 6 were no significant differences compared to group 1. The VEGF ELİSA levels were statistically significantly lower in group 3, 5 and 6 compared to group 2 (p < 0.05). There was no statistically difference between VEGF ELİSA levels of group 2 and 4 (p > 0.05).

CONCLUSIONS

Sorafenib was as effective as bevacizumab in the regression of corneal neovascularization. The effect of sorafenib seems to be dose-dependent. The low doses and twice a day administration are important advantages of sorafenib.

Macrophage migration inhibitory factor is critical for dengue NS1-induced endothelial glycocalyx degradation and hyperpermeability

Vascular leakage is one of the salient characteristics of severe dengue. Nonstructural protein 1 (NS1) of dengue virus (DENV) can stimulate endothelial cells to secrete endothelial hyperpermeability factor, macrophage migration inhibitory factor (MIF), and the glycocalyx degradation factor heparanase 1 (HPA-1). However, it is unclear whether MIF is directly involved in NS1-induced glycocalyx degradation. In this study, we observed that among NS1, MIF and glycocalyx degradation-related molecules, the HPA-1, metalloproteinase 9 (MMP-9) and syndecan 1 (CD138) serum levels were all increased in dengue patients, and only NS1 and MIF showed a positive correlation with the CD138 level in severe patients. To further characterize and clarify the relationship between MIF and CD138, we used recombinant NS1 to stimulate human cells in vitro and challenge mice in vivo. Our tabulated results suggested that NS1 stimulation could induce human endothelial cells to secrete HPA-1 and immune cells to secrete MMP-9, resulting in endothelial glycocalyx degradation and hyperpermeability. Moreover, HPA-1, MMP-9, and CD138 secretion after NS1 stimulation was blocked by MIF inhibitors or antibodies both in vitro and in mice. Taken together, these results suggest that MIF directly engages in dengue NS1-induced glycocalyx degradation and that targeting MIF may represent a possible therapeutic approach for preventing dengue-induced vascular leakage.

Old and new applications of non-anticoagulant heparin

The aim of this chapter is to provide an overview of non-anticoagulant effects of heparins and their potential use in new therapeutic applications. Heparin and heparin derivatives have been tested in inflammatory, pulmonary and reproductive diseases, in cardiovascular, nephro- and neuro-tissue protection and repair, but also as agents against angiogenesis, atheroschlerosis, metastasis, protozoa and viruses. Targeting and inhibition of specific mediators involved in the inflammatory process, promoting some of the above mentioned pathologies, are reported along with recent studies of heparin conjugates and oral delivery systems. Some reports from the institute of the authors, such as those devoted to glycol-split heparins are also included. Among the members and derivatives of this class, several are undergoing clinical trials as antimetastatic and antimalarial agents and for the treatment of labour pain and severe hereditary anaemia. Other heparins, whose therapeutic targets are non-anticoagulant such as nephropathies, retinopathies and cystic fibrosis are also under investigation.

Mesenchymal stem cells improve healing of the cornea after alkali injury

PURPOSE

To evaluate the efficacy of mesenchymal stem cells (MSCs) to ameliorate the consequences of corneal alkali injuries.

METHODS

Corneal alkali injuries were created in 30 rabbit eyes. The MSC group (n = 15) were treated with intrastromal and subconjunctival injections of phosphate-buffered saline (PBS) containing 2 × 10(6) MSCs and topical application. The control group (n = 15) was treated with PBS by the same applications forms. Drops of standard treatment (ascorbate 10 %, citrate 10 %, tobramycin, dexamethasone, Cyclogyl) were instilled for 2 weeks. Rabbits underwent slit-lamp examination, fluorescein staining, photography, and were evaluated for corneal neovascularization, opacification, and epithelial defects. Tear secretion and IOP were also evaluated. Furthermore, the concentration of Serumglutamic-pyruvic transaminase (SGPT) and vascular endothelial factor (VEGF) were measured. Immunohistochemistry was also performed for a-SMA and Ki-67.

RESULTS

Eyes treated with MSCs showed better recovery. The mean neovascularized area was significantly smaller in the MSC group (p < 0.05). A significant difference in the degree of corneal opacification and re-epithelialization was also observed, as well as the IOP at 21 and 28 posttraumatic days (p < 0.05). Histology showed that MSCs resulted in almost normal architecture of eye tissues. After the MSCs infusion, SGPT and VEGF levels in cornea were significantly reduced. Immunohistochemistry demonstrated a reduction of a-SMA in the MSC group with higher mitotic-regenerative activity with the presence of Ki67.

CONCLUSIONS

Our study represents a first step in understanding the possibilities of the MSC approach to treatment of alkali injuries of the cornea and shows that such an approach improves clinical outcomes and leads to better prognosis.

Heparin/Heparan sulfate proteoglycans glycomic interactome in angiogenesis: biological implications and therapeutical use

Angiogenesis, the process of formation of new blood vessel from pre-existing ones, is involved in various intertwined pathological processes including virus infection, inflammation and oncogenesis, making it a promising target for the development of novel strategies for various interventions. To induce angiogenesis, angiogenic growth factors (AGFs) must interact with pro-angiogenic receptors to induce proliferation, protease production and migration of endothelial cells (ECs). The action of AGFs is counteracted by antiangiogenic modulators whose main mechanism of action is to bind (thus sequestering or masking) AGFs or their receptors. Many sugars, either free or associated to proteins, are involved in these interactions, thus exerting a tight regulation of the neovascularization process. Heparin and heparan sulfate proteoglycans undoubtedly play a pivotal role in this context since they bind to almost all the known AGFs, to several pro-angiogenic receptors and even to angiogenic inhibitors, originating an intricate network of interaction, the so called "angiogenesis glycomic interactome". The decoding of the angiogenesis glycomic interactome, achievable by a systematic study of the interactions occurring among angiogenic modulators and sugars, may help to design novel antiangiogenic therapies with implications in the cure of angiogenesis-dependent diseases.

Genomics of corneal wound healing: a review of the literature

Corneal wound healing is a complex process: its mechanisms and the underlying genetic control are not fully understood. It involves the integrated actions of multiple growth factors, cytokines and proteases produced by epithelial cells, stromal keratocytes, inflammatory cells and lacrimal gland cells. Following an epithelial insult, multiple cytokines are released triggering a cascade of events that leads to repair the epithelial defect and remodelling of the stroma to minimize the loss of transparency and function. In this review, we examine the literature surrounding the genomics of corneal wound healing with respect to the following topics: epithelial and stromal wound healing (including inhibition); corneal neovascularisation; the role of corneal nerves in wound healing; the endothelium; the role of aquaporins and aptamers. We also examine the effect of ectasia on corneal wound healing with regard to keratoconus and following corneal surgery. A better understanding of the cellular and molecular changes that occur during repair of corneal wounds will provide the opportunity to design treatments that selectively modulate key phases of the healing process resulting in scars that more closely resemble normal corneal architecture.

Inhibition of corneal neovascularization with the combination of bevacizumab and plasmid pigment epithelium-derived factor-synthetic amphiphile INTeraction-18 (p-PEDF-SAINT-18) vector in a rat corneal experimental angiogenesis model

Bevacizumab, a 149-kDa protein, is a recombinant humanized monoclonal antibody to VEGF. PEDF, a 50-kDa glycoprotein, has demonstrated anti-vasopermeability properties. In this study, we demonstrated that the combination of bevacizumab and plasmid pigment epithelium-derived factor-synthetic amphiphile INTeraction-18 (p-PEDF-SAINT-18) has a favorable antiangiogenic effect on corneal NV. Four groups (Group A: 0 μg + 0 μg, B: 0.1 μg + 0.1 μg, C: 1 μg + 1 μg, and D: 10 μg + 10 μg) of bevacizumab + p-PEDF-SAINT-18 were prepared and implanted into the rat subconjunctival substantia propria 1.5 mm from the limbus on the temporal side. Then, 1 μg of p-bFGF-SAINT-18 was prepared and implanted into the rat corneal stroma 1.5 mm from the limbus on the same side. The inhibition of NV was observed and quantified from days 1 to 60. Biomicroscopic examination, western blot analysis and immunohistochemistry were used to analyze the 18-kDa bFGF, 50-kDa PEDF and VEGF protein expression. No inhibition activity for normal limbal vessels was noted. Subconjunctival injection with the combination of bevacizumab and p-PEDF-SAINT-18 successfully inhibited corneal NV. The bFGF and PEDF genes were successfully expressed as shown by western blot analysis, and a mild immune response to HLA-DR was shown by immunohistochemistry. We concluded that the combination of bevacizumab and p-PEDF-SAINT-18 may have more potent and prolonged antiangiogenic effects, making it possible to reduce the frequency of subconjunctival bevacizumab administration combined with a relatively safe profile and low toxicity.

Immunological disruption of antiangiogenic signals by recruited allospecific T cells leads to corneal allograft rejection

Corneal transplantation is the most common solid organ transplantation. The immunologically privileged nature of the cornea results in high success rates. However, T cell-mediated rejection is the most common cause of corneal graft failure. Using antiangiogenesis treatment to prevent corneal neovascularization, which revokes immune privilege, prevents corneal allograft rejection. Endostatin is an antiangiogenic factor that maintains corneal avascularity. In this study, we directly test the role of antiangiogenic and immunological signals in corneal allograft survival, specifically the potential correlation of endostatin production and T cell recruitment. We report that 75% of the corneal allografts of BALB/c mice rejected after postoperative day (POD) 20, whereas all syngeneic grafts survived through POD60. This correlates with endogenous endostatin, which increased and remained high in syngeneic grafts but decreased after POD10 in allografts. Immunostaining demonstrated that early recruitment of allospecific T cells into allografts around POD10 correlated with decreased endostatin production. In Rag(-/-) mice, both allogeneic and syngeneic corneal grafts survived; endostatin remained high throughout. However, after T cell transfer, the allografts eventually rejected, and endostatin decreased. Furthermore, exogenous endostatin treatment delayed allograft rejection and promoted survival secondary to angiogenesis inhibition. Our results suggest that endostatin plays an important role in corneal allograft survival by inhibiting neovascularization and that early recruitment of allospecific T cells into the grafts promotes destruction of endostatin-producing cells, resulting in corneal neovascularization, massive infiltration of effector T cells, and ultimately graft rejection. Therefore, combined antiangiogenesis and immune suppression will be more effective in maintaining corneal allograft survival.

The Chick Embryo Chorioallantoic Membrane as an In Vivo Assay to Study Antiangiogenesis

Antiangiogenesis, e.g., inhibition of blood vessel growth, is being investigated as a way to prevent the growth of tumors and other angiogenesis-dependent diseases. Pharmacological inhibition interferes with the angiogenic cascade or the immature neovasculature with synthetic or semi-synthetic substances, endogenous inhibitors or biological antagonists.The chick embryo chorioallantoic membrane (CAM) is an extraembryonic membrane, which serves as a gas exchange surface and its function is supported by a dense capillary network. Because its extensive vascularization and easy accessibility, CAM has been used to study morphofunctional aspects of the angiogenesis process in vivo and to study the efficacy and mechanism of action of pro- and anti-angiogenic molecules. The fields of application of CAM in the study of antiangiogenesis, including our personal experience, are illustrated in this review article.

Inhibition of corneal neovascularization with plasmid pigment epithelium-derived factor (p-PEDF) delivered by synthetic amphiphile INTeraction-18 (SAINT-18) vector in an experimental model of rat corneal angiogenesis

The use of Synthetic Amphiphile INTeraction-18 (SAINT-18) carrying plasmid pigment epithelium-derived factor (p-PEDF) as an anti-angiogenesis strategy to treat corneal neovascularization in a rat model was evaluated. Four partially dried forms (Group A: 0 microg, B: 0.1 microg, C: 1 microg, D: 10 microg) of a p-PEDF-SAINT-18 were prepared and implanted into the rat subconjunctival substantia propria 1.5 mm from the limbus at the temporal side. The 1 microg of plasmid-basic fibroblast growth factor--SAINT-18 (p-bFGF-SAINT-18) (1 microg) was prepared and implanted into the rat corneal stroma 1.5 mm from the limbus on the same side. Inhibition of neovascularization was observed and quantified from day 1 to day 60. PEDF (50-kDa) and bFGF (18-kDa) protein expression were analyzed by biomicroscopic examination, Western blot analysis, and immunohistochemistry. Gene expression in corneal and conjunctival tissue was observed as early as 3 days after gene transfer and stably lasted for over 3 months with minimal immune reaction. Subconjunctival injection of a highly efficient p-PEDF-SAINT-18 successfully inhibited corneal neovascularization. Successful gene expression of bFGF, PEDF and a mild immune response of HLA-DR were shown by immunohistochemistry staining. We concluded that SAINT-18 was capable of directly delivering genes to the ocular surface by way of subconjunctival injection, and delivered sustained, high levels of gene expression in vivo to inhibit angiogenesis.

The inhibitory effects of trastuzumab on corneal neovascularization

PURPOSE

To investigate the effect of systemic administration of trastuzumab in the prevention of experimentally induced corneal neovascularization in a rat model.

DESIGN

An experimental animal study.

METHODS

Sixteen male Wistar-Albino rats weighing 250 g to 300 g were used in the study. Silver nitrate sticks (75% silver nitrate, 25% potassium nitrate) were used to induce chemical cauterization on the corneas of 16 eyes. The rats were randomized to 1 of 2 groups: Group 1 (n = 8) received intraperitoneally 1 ml (4 mg/kg) trastuzumab and Group 2 (n = 8) received 1 ml saline. The corneal surface covered with neovascular vessels was measured on the photographs as the percentage of the total area of the cornea by using computer imaging analysis on the eighth day. The corneas obtained from rats were evaluated for vascular endothelial growth factor (VEGF) immunostaining semicantitatively. The number of the corneal neovascularizations were also determined on slides. The results were evaluated with the Mann-Whitney U test.

RESULTS

The burn stimulus was similar between groups. The average neovascularization area in treatment group was statistically smaller than control (P = .008). The mean VEGF staining intensity of epithelial and endothelial layers of cornea in treatment group was less than control (P = .038 and P = .041, respectively). The stroma of the treatment group showed less staining, but the difference was not significant (P = .056). The number of corneal neovascularizations on slides in trastuzumab treated eyes were less than the control group (P = .02).

CONCLUSION

Systemic administration of trastuzumab is effective in prevention of the corneal neovascularization.

Membrane type-1 matrix metalloproteinase potentiates basic fibroblast growth factor-induced corneal neovascularization

Corneal neovascularization is one of the leading causes of blindness. The aim of this study was to evaluate the pro-angiogenic role of corneal fibroblast-derived membrane type-1 matrix metalloproteinase (MT1-MMP) on basic fibroblast growth factor (bFGF)-induced corneal neovascularization in vivo and in vitro. Immunohistochemical studies demonstrated that MT1-MMP was expressed in keratocytes and immortalized corneal fibroblast cell lines. Vascular endothelial growth factor protein levels were increased after bFGF-stimulation of wild-type fibroblast cells compared with MT1-MMP knockout fibroblast cells. Corneal vascularization was significantly increased after a combination of bFGF pellet implantation and naked MT1-MMP DNA injection in wild-type mouse corneas compared with either bFGF pellet implantation or naked MT1-MMP DNA-injected corneas. Western blotting analysis of the phosphorylation levels of the key signaling molecules (p38, JNK, and ERK) demonstrated that phosphorylation levels of both p38 and JNK were diminished after bFGF stimulation of MT1-MMP knockout cells compared with wild-type and MT1-MMP knockin cells. These results suggest that MT1-MMP potentiates bFGF-induced corneal neovascularization, likely by modulating the bFGF signal transduction pathway.

Subconjunctival bevacizumab for corneal neovascularization

PURPOSE

To describe whether subconjunctival bevacizumab decreases corneal neovascularization in patients with ocular surface inflammatory diseases.

METHODS

The study is a retrospective case series that includes 8 eyes of 7 patients with corneal neovascularization. Patients received 1-3 injections of 2.5 mg subconjunctival bevacizumab. Morphologic changes were assessed clinically by the same investigator at each visit.

RESULTS

Subconjunctival bevacizumab was well-tolerated without obvious corneal side effects. All 8 eyes of the 7 patients showed a reduction in the neovascularized area.

CONCLUSIONS

Subconjunctival bevacizumab may provide an additional strategy in improving vision or improving success of corneal grafts in these patients.

A novel vector system for gene transfer into the cornea using a partially dried plasmid expressing 18 basic fibroblast growth factor-synthetic amphiphile INTeraction-18 (SAINT-18) complex

PURPOSE

We describe a novel vector system of nonviral gene transfer into the cornea using a partially dried form of a plasmid expressing 18-kDa basic fibroblast growth factor (p-bFGF)-synthetic amphiphile INTeraction-18 (SAINT-18) complex.

METHODS

Corneal neovascularization (NV) was evaluated in 48 eyes of Sprague-Dawley rats after implantation of SAINT-18 containing 2 micro g of plasmid-expressing green fluorescent protein (p-GFP; control group), 0.2 micro g, 2 micro g, or 20 micro g of p-bFGF from day 0 to day 60. bFGF protein expression was analyzed by Western blotting and immunohistochemistry.

RESULTS

The p-bFGF-SAINT-18 complex induced dose-dependent corneal neovascularization, which reached a maximum on days 15-21 in the 20-micro g p-bFGF group, days 12-18 in the 2-micro g p-bFGF group, and on days 9-15 in the 0.2-micro g p-bFGF group, and then regressed progressively. No NV was observed in the p-GFP group.

CONCLUSIONS

This noninflammatory corneal transfection model using partially dried p-bFGF-SAINT-18 complex allows precise localization of tranfection reagents for producing corneal neovascularization.

Polyanionic drugs and viral oncogenesis: a novel approach to control infection, tumor-associated inflammation and angiogenesis

Polyanionic macromolecules are extremely abundant both in the extracellular environment and inside the cell, where they are readily accessible to many proteins for interactions that play a variety of biological roles. Among polyanions, heparin, heparan sulfate proteoglycans (HSPGs) and glycosphingolipids (GSLs) are widely distributed in biological fluids, at the cell membrane and inside the cell, where they are implicated in several physiological and/or pathological processes such as infectious diseases, angiogenesis and tumor growth. At a molecular level, these processes are mainly mediated by microbial proteins, cytokines and receptors that exert their functions by binding to HSPGs and/or GSLs, suggesting the possibility to use polyanionic antagonists as efficient drugs for the treatment of infectious diseases and cancer. Polysulfated (PS) or polysulfonated (PSN) compounds are a heterogeneous group of natural, semi-synthetic or synthetic molecules whose prototypes are heparin and suramin. Different structural features confer to PS/PSN compounds the capacity to bind and inhibit the biological activities of those same heparin-binding proteins implicated in infectious diseases and cancer. In this review we will discuss the state of the art and the possible future development of polyanionic drugs in the treatment of infectious diseases and cancer.

Inhibition of experimental angiogenesis of cornea by various doses of doxycycline and combination of triamcinolone acetonide with low-molecular-weight heparin and doxycycline

PURPOSE

To evaluate the effect of topically administered doxycycline in various doses; the combination of triamcinolone acetonide and low-molecular-weight heparin (LMWH); and the combination of triamcinolone acetonide and doxycycline on experimental corneal neovascularization in rats.

METHODS

This project is the combination of 2 separate studies. First, the chemical cauterization of corneas in 36 eyes of 36 Long Evans male rats was performed by using silver nitrate/potassium nitrate sticks. Topical instillation of doxycycline at 0.05% (pH = 3.3), 0.1% (pH = 3.1), 1% (pH = 2.3), 2% (pH = 2.1), 2% (pH neutralized to 7.4), and normal saline continued for 7 days. Second, the chemical cauterization of the corneas in 24 eyes of 24 rats was achieved by application of silver nitrate/potassium nitrate sticks. Topical instillation of triamcinolone acetonide (10 microg/mL) and either LMWH (10 mg/mL) or doxycycline (10 mg/mL) was compared with normal saline treatment of 7 days. For both studies, the percent area of the cornea covered by neovascularization and scar in each group was calculated separately by using computer software on digital photographs. All corneas were evaluated histopathologically in study and control groups.

RESULTS

The mean percent area of corneal neovascularization determined in the eyes given doxycycline 0.05%, 0.1%, 1%, 2%, and 2% (pH neutralized) study groups and control groups was 69.8% +/- 18.0%, 64.5% +/- 14.0%, 56.4% +/- 20.8%, 54.8% +/- 6.0%, 36.2% +/- 4.3%, and 69.4% +/- 5.7%, respectively. The mean of percent area of neovascularization in the 2% doxycycline (pH neutralized) doxycycline group was significantly less than that of the control group and the <1% doxycycline concentrations (P < 0.05). The percent corneal neovascularization in the 2% (pH neutralized) doxycycline group was not significantly different from that of the 1% and 2% doxycycline groups (P < 0.05). There was no significant difference in percent area of corneal scar between control and study groups (P > 0.05). The mean percent area of corneal neovascularization in triamcinolone acetonide and LMWH, triamcinolone acetonide and doxycycline, and control groups was 2.35% +/- 4.42%, 9.42% +/- 6.8%, and 64.7% +/- 10.0%, respectively. The mean percent area of neovascularization in the triamcinolone acetonide plus LMWH or triamcinolone acetonide plus doxycycline groups was significantly different from that of the control group (P = 0.001 for both). There was no significant difference between study groups with regard to percent area of neovascularization or percent area of corneal scar between the control and study groups.

CONCLUSIONS

Topically administered combinations of triamcinolone acetonide plus LMWH or triamcinolone acetonide plus doxycycline had effects that contributed to efficient suppression of corneal neovascularization; these drugs were ineffective at similar concentrations used alone. Topically administered 2% (pH neutralized) doxycycline has antiangiogenic effects, which contributed to significant suppression on corneal neovascularization. This drug may be therapeutically beneficial in treatment of corneal neovascularization in clinical trials.

Subconjunctival bevacizumab injection for corneal neovascularization

PURPOSE

To report on the clinical use of subconjunctival bevacizumab in patients with corneal neovascularization.

METHODS

The charts of 10 consecutive patients with corneal neovascularization who received subconjunctival injections of bevacizumab (2.5 mg/0.1 mL) were reviewed. Digital photographs of the cornea were graded by 2 masked observers for density, extent, and centricity of corneal vascularization. Image analysis was used to determine the area of cornea covered by neovascularization as a percentage of the total corneal area.

RESULTS

No significant ocular or systemic adverse events were observed during 3.5 +/- 1.1 months of follow-up. Seven patients showed partial regression of vessels. The extent decreased from 6.0 +/- 1.2 (SD) clock hours before the injection to 4.6 +/- 1.0 clock hours after bevacizumab injection (P = 0.008). Density decreased from 2.7 +/- 0.2 to 1.9 +/- 0.3, respectively. (P = 0.007). No change was noticed in the centricity of corneal vessels. Corneal neovascularization covered, on average, 14.8% +/- 2.5% (SD) of the corneal surface before the injections, compared with 10.5% +/- 2.8% (P = 0.36, t test) after bevacizumab injection. Therefore, bevacizumab decreased corneal neovascularization by 29%.

CONCLUSIONS

Short-term results suggest that subconjunctival bevacizumab is well tolerated and associated with a partial regression of corneal neovascularization.

Inhibition of corneal neovascularization by subconjunctival bevacizumab in an animal model

PURPOSE

To evaluate the effect of subconjunctival injection of bevacizumab on experimentally induced corneal neovascularization.

DESIGN

Experimental animal study.

METHODS

Twelve New Zealand white rabbits were involved, divided equally into four groups. Only one eye per rabbit was used. Topical instillation of 10 microl 5% NaOH solution was used, under general anesthesia, to induce corneal neovascularization secondary to corneal alkali burn in groups 2, 3, and 4. A single dose of 3.75 mg (25 mg/ml) bevacizumab was injected subconjunctivally. Group 1 (control group 1) was neither cauterized nor treated. Group 2 (control group 2) received a sham injection of balanced salt solution on day 14. Group 3 was treated on day 14 (after corneal neovascularization had been established). Group 4 was treated on day 1. Digital photographs were obtained and analyzed during the entire 28-day procedure. The area of neovascularization and scarring were measured in terms of the percentage of corneal surface affected.

RESULTS

On day 28, the difference of neovascularization between groups 2, 3, and 4 was found to be statistically significant at the .05 level (one-way analysis of variance [ANOVA]): group 4 (4.7%+/-3.1%)<group 3 (13.3%+/-2.3%)<group 2 (41.0%+/-3.6%; P<.05, Mann-Whitney U test). In group 3, the area of neovascularization decreased 14 days after treatment by 42%. Neovascularization was almost completely absent in group 4. The development of scarring was unaffected by bevacizumab (P>.1, one-way ANOVA). No side effects were noted.

CONCLUSIONS

Subconjunctival administration of bevacizumab inhibits corneal neovascularization effectively in the rabbit experimental model, especially if administered early.

Inhibition of corneal angiogenesis by ascorbic acid in the rat model

PURPOSE

To evaluate the effect of topically administered ascorbic acid on experimentally induced corneal neovascularization in the rat model.

MATERIALS AND METHODS

Corneal chemical cauterization of 72 eyes in Long-Evans male rats was performed using silver nitrate/potassium nitrate sticks. Nine groups of eight eyes were used to evaluate eight concentrations of ascorbic acid with one group of eight eyes serving as a control. Topical instillation of 100 mg/ml non-pH-neutralized ascorbic acid was performed in one group while the remaining seven groups were evaluated using pH-neutralized ascorbic acid in concentrations of 100 mg/ml, 50 mg/ml, 10 mg/ml, 5 mg/ml, 1 mg/ml, 500 microg/ml, and 250 microg/ml.

RESULTS

The percentage of corneal neovascularization and burn stimulus score was determined for all the eyes. The means of percent of corneal neovascularization in ascorbic acid 100 mg/ml (non-neutralized), 100 mg/ml, 50 mg/ml, 10 mg/ml, 5 mg/ml, 1 mg/ml, 500 microg/ml, 250 microg/ml, and control group were 17.50 +/- 12.80 (p = 0.001), 17.00 +/- 19.30 (p = 0.001), 15.25 +/- 13.26 (p = 0.001), 17.62 +/- 11.89 (p = 0.001), 28.87 +/- 23.08 (p = 0.001), 29.62 +/- 16.91 (p = 0.001), 60.12 +/- 8.50 (p = 0.04), 65.62 +/- 2.26 (p = 0.185), and 68.25 +/- 4.06, respectively (Tables 1 and 2). All animals had a burn score of 2+ or higher (Table 1).

CONCLUSION

Ascorbic acid applied in a topical solution appears to inhibit corneal neovascularization in the rat model of inflammatory neovascularization in concentrations in a dose-dependent manner. The optimal dose-effect relation was in our model found in concentrations between 1 mg and 500 microg/ml. At concentrations below 500 microg/ml there was no statistically significant inhibition in the degree of corneal neovascularization compared to control.

Proangiogenic role of ephrinB1/EphB1 in basic fibroblast growth factor-induced corneal angiogenesis

Corneal neovascularization is a vision-threatening condition caused by various ocular pathological conditions. The aim of this study was to evaluate the function of the ephrin ligands and Eph receptors in vitro and in vivo in corneal angiogenesis in a mouse model. The Eph tyrosine kinase receptors and their ligands, ephrins, are expressed on the cell surface. The functions of Eph and ephrins have been shown to regulate axonal guidance, segmentation, cell migration, and angiogenesis. Understanding the roles of Eph and ephrin in corneal angiogenesis may provide a therapeutic intervention for the treatment of angiogenesis-related disorders. Immunohistochemical studies demonstrated that ephrinB1 and EphB1 were expressed in basic fibroblast growth factor (bFGF)-induced vascularized corneas. EphB1 was specifically colocalized with vascular endothelial marker CD31 surrounded by type IV collagen. EphrinB1 was expressed in corneal-resident keratocytes and neutrophils. Recombinant ephrinB1-Fc, which induces EphB receptor activation, enhanced bFGF-induced tube formation in an in vitro aortic ring assay and promoted bFGF-induced corneal angiogenesis in vivo in a corneal pocket assay. Synergistically enhanced and sustained activation of extracellular signal-regulated kinase was noted in vascular endothelial cell lines after stimulation with ephrin B1 and bFGF combinations. These results suggest that ephrinB1 plays a synergistic role in corneal neovascularization.

Inhibition of experimental corneal neovascularisation by bevacizumab (Avastin)

AIM

To evaluate the effect of topically administered bevacizumab (Avastin) on experimental corneal neovascularisation in rats.

METHODS

Silver nitrate sticks (75% silver nitrate, 25% potassium nitrate) were used to perform chemical cauterisation on the corneas of 16 eyes from 16 male Long Evans rats. For the following 7 days, the 10 eyes in the treatment group were instilled with bevacizumab 4 mg/ml drops twice daily, whereas the 6 eyes in the control group received placebo (normal saline drops twice daily). Digital photographs of the cornea were analysed to determine the area of cornea covered by neovascularisation as a percentage of the total corneal area.

RESULTS

In the bevacizumab-treated eyes, neovascularisation covered, on average, 38.2% (15.5%) (mean (SD)) of the corneal surface compared with 63.5% (5.0%) in the control group (p<0.02, Mann-Whitney U test).

CONCLUSION

Topically administered bevacizumab (Avastin) at a concentration of 4 mg/ml limits corneal neovascularisation following chemical injury in the male Long Evans rat model.

Adhesion inhibition "in vitro" by heparin derivatives correlates with their activity on angiogenesis in mice

Heparin (HEP) play an important role in angiogenesis. Inhibition of matrix degrading enzymes and binding to adhesion molecules are some of the interaction mechanism. The bleeding risk and the need of parenteral administration, restrict the therapeutic use of HEP as angiogenesis modulator; presently derivatives, with different pharmacokinetic and anticoagulant properties, are available. In this study the "in vitro" anti-adhesion activity, tested with PMNs and endothelial cells, was compared with the effect on angiogenesis, evaluated in Matrigel implanted mice. Some HEP derivatives, with low anticoagulant activity, showed a significant angiogenesis inhibition. A positive correlation between adhesion inhibition in vitro and anti-angiogenesis effect in vivo was found suggesting that the interaction with adhesion molecules by HEP derivatives play a relevant role in the angiogenesis control.

Inhibition of experimental angiogenesis of cornea by somatostatin

BACKGROUND

This study evaluated the inhibitory activity of somatostatin 14 on the angiogenesis of cornea in vivo.

METHODS

Corneal neovascularization was induced with a pellet containing 90 ng of basic fibroblast growth factor (bFGF) in a rat corneal pocket model. Three kinds of pellets were made containing bFGF plus somatostatin (SST) 0 ng, 20 ng and 200 ng for the control group, group 1 and group 2, respectively. Neovascularization was observed biomicroscopically from day 4 to day 8, and the corneas were then examined for changes in histology. Quantitation of angiogenesis in the cornea was accomplished by caliper and image analysis.

RESULTS

The 200-ng dose of SST showed significant inhibition of both length and area of neovascularization on day 7 (0.62+/-0.11 mm vs 1.29+/-0.16 mm, 0.50+/-0.16 mm2 vs 1.35+/-0.29mm2, group 2 vs control; P<0.05). The 20 ng of somatostatin did not demonstrate any significant inhibition of neovascularization compared with the control group.

CONCLUSION

Our study demonstrated that SST 14 can reduce bFGF-induced corneal angiogenesis. This shows the potential value of somatostatin in the treatment of corneal neovascularization.

Growth factors in corneal wound healing following refractive surgery: A review

The first part of this review article aims to provide important basic definitions of growth factor terminology, and to put forward a model for understanding the role of growth factors in a wound healing context. In the second part of the paper, we review the literature on growth factors in the cornea, including that on changes associated with wound healing following refractive surgery in the epithelial, stromal, and endothelial layers. The role of growth factors in stromal removal, corneal neovascularization, corneal innervation and wound healing is considered. The importance of the epithelial-stromal interaction is discussed, including the role of growth factors in keratocyte apoptosis. In the final section, we review the current literature on endogenous and exogenous modulation of growth factors in corneal wound healing. This includes important in vitro work but aims to emphasize clinically relevant results. Photorefractive keratectomy (PRK) may have short-term complications such as pain and haze, whereas laser in situ keratomilieusis (LASIK) may have longer-term adverse effects on corneal biomechanics. The emerging technique of laser epithelial keratomilieusis (LASEK) provides an interesting alternative wound which may be less susceptible to the inherent complications of PRK and LASIK. At present, the phenomenon of iatrogenic keratectasia following LASIK is not fully understood, but these features of wound healing following PRK may be amenable to growth factor modulation.