Suppressive effects of indomethacin on thermally induced neovascularization of rabbit corneas

PRODUCTION AND APPLICATION OF ANGIOSTATINS FOR THE TREATMENT OF OCULAR NEOVASCULAR DISEASES

Angiostatins comprise a group of kringle-containing proteolytically-derived fragments of plasminogen/plasmin, which act as potent inhibitory mediators of endothelial cells proliferation and migration. Angiostatins are involved in modulation of vessel growth in healthy tissues and various pathological conditions associated with aberrant neovascularization. The aim of the present paper was to summarize available information, including our own experimental data, on prospects of angiostatin application for treatment of ocular neovascular diseases (OND), focusing on retinal pathologies and corneal injury. In particular, literature data on prospective and retrospective studies, clinical trials and animal models relating to the pathophysiology, investigation and management of OND are described. Special emphasis was made on the laboratory approaches of production of different angiostatin isoforms, as well as comparison of antiangiogenic capacities of native and recombinant angiostatin polypeptides. Several studies reported that angiostatins may completely abolish pathologic angiogenesis in diabetic proliferative retinopathy without affecting normal retinal vessel development and without exhibiting adverse side effects. Angiostatins have been tested as a tool for corneal antiangiogenesis target therapy in order to manage diverse ocular surface pathological conditions induced by traumas, chemical burns, previous surgery, chronic contact lens wear, autoimmune diseases, keratitis and viral infections (herpes, COVID-19), corneal graft rejection, etc. Among all known angiostatin species, isolated K5 plasminogen fragment was shown to display the most potent inhibitory activity against proliferation of endothelial cells via triggering multiple signaling pathways, which lead to cell death and resulting angiogenesis suppression. Application of adenoviral genetic construct encoding angiostatin K5 as a promising tool for OND treatment illustrates a vivid example of upcoming revolution in local gene therapy. Further comprehensive studies are necessary to elucidate the clinical potential and optimal regimes of angiostatinbased intervention modalities for treating ocular neovascularization.

Revascularization after angiogenesis inhibition favors new sprouting over abandoned vessel reuse

Inhibiting pathologic angiogenesis can halt disease progression, but such inhibition may offer only a temporary benefit, followed by tissue revascularization after treatment stoppage. This revascularization, however, occurs by largely unknown phenotypic changes in pathologic vessels. To investigate the dynamics of vessel reconfiguration during revascularization, we developed a model of reversible murine corneal angiogenesis permitting longitudinal examination of the same vasculature. Following 30 days of angiogenesis inhibition, two types of vascular structure were evident: partially regressed persistent vessels that were degenerate and barely functional, and fully regressed, non-functional empty basement membrane sleeves (ebms). While persistent vessels maintained a limited flow and retained collagen IV+ basement membrane, CD31+ endothelial cells (EC), and α-SMA+ pericytes, ebms were acellular and expressed only collagen IV. Upon terminating angiogenesis inhibition, transmission electron microscopy and live imaging revealed that revascularization ensued by a rapid reversal of EC degeneracy in persistent vessels, facilitating their phenotypic normalization, vasodilation, increased flow, and subsequent new angiogenic sprouting. Conversely, ebms were irreversibly sealed from the circulation by excess collagen IV deposition that inhibited EC migration and prevented their reuse. Fully and partially regressed vessels therefore have opposing roles during revascularization, where fully regressed vessels inhibit new sprouting while partially regressed persistent vessels rapidly reactivate and serve as the source of continued pathologic angiogenesis.

Prevention of Corneal Neovascularization by Adenovirus Encoding Human Vascular Endothelial Growth Factor Soluble Receptor (s-VEGFR1) in Lacrimal Gland

Purpose

The aims of this study were (1) to determine the efficacy of adenovirus vector serotype 5 (Ad) encoding human soluble VEGF receptor 1 (s-VEGFR1) gene transfer to the lacrimal gland (LG); (2) to investigate whether expression of s-VEGFR1 prevents corneal neovascularization (CNV) induced by alkali burns; and (3) to evaluate the safety of the procedure.

Methods

AdVEGFR1 vectors (25 μL, 1 × 1010 pfu/mL) were injected in the right LGs of rats and were compared with AdNull vector (25 μL, 1 × 1010 pfu/mL) or 25 μL of saline (Control) before cornea alkali burns with 1 M NaOH. After 7 days, CNV was documented at the slit lamp. Tear secretion was measured with phenol red threads. The animals were tested for s-VEGFR1 mRNA and protein in the LG by quantitative (q)PCR and immunohistochemistry staining, respectively. qPCR was used to compare the mRNA levels of IL-1β, IL-6, and TNF-α in the LG and ipsilateral trigeminal ganglion (TG).

Results

Ad-VEGFR1 transfected 83% (10/12) of the rats. VEGFR1 was present in LG acinar cells. CNV was prevented in 9 of 12 animals in the Ad-VEGFR1 group, compared with the Ad-Null (3:10) and Control groups (1:10) (P = 0.0317). The tear secretion and cytokine mRNA levels in the LG and TG were similar in all three groups (P > 0.05).

Conclusions

Adenoviral vector gene transfer was safe for LG structure and function. The LG as the target tissue showed local expression of human s-VEGFR1, and CNV was prevented in most of the eyes exposed to alkali burns.

Anti-Inflammatory and Anti-Fibrotic Effects of Human Amniotic Membrane Mesenchymal Stem Cells and Their Potential in Corneal Repair

Acute ocular chemical burns are ophthalmic emergencies requiring immediate diagnosis and treatment as they may lead to permanent impairment of vision. The clinical manifestations of such burns are produced by exacerbated innate immune response via the infiltration of inflammatory cells and activation of stromal fibroblasts. New therapies are emerging that are dedicated to repair mechanisms that improve the ocular surface after damage; for example, transplantation of stem cells (SC) has been successfully reported for this purpose. The pursuit of easily accessible, noninvasive procedures to obtain SC has led researchers to focus on human tissues such as amniotic membrane. Human amniotic mesenchymal SC (hAM-MSC) inhibits proinflammatory and fibrotic processes in different diseases. hAM-MSC expresses low levels of classical MHC-I and they do not express MHC-II, making them suitable for regenerative medicine. The aim of this study was to evaluate the effect of intracameral injection of hAM-MSC on the clinical manifestations, the infiltration of inflammatory cells, and the activation of stromal fibroblasts in a corneal alkali-burn model. We also determined the in vitro effect of hAM-MSC conditioned medium (CM) on α-SMA⁺ human limbal myofibroblast (HLM) frequency and on release of neutrophil extracellular traps (NETs). Our results show that intracameral hAM-MSC injection reduces neovascularization, opacity, stromal inflammatory cell infiltrate, and stromal α-SMA⁺ cells in our model. Moreover, in in vitro assays, CM from hAM-MSC decreased the quantity of α-SMA⁺ HLM and the release of NETs. These results suggest that intracameral hAM-MSC injection induces an anti-inflammatory and anti-fibrotic environment that promotes corneal wound healing. Stem Cells Translational Medicine 2018;7:906-917.

Fluorescent angiogenesis models using gelfoam® implanted in transgenic mice expressing fluorescent proteins

Fidler's group described an in vivo angiogenesis assay utilizing Gelfoam(®) sponges impregnated with agarose and proangiogenic factors. Vessels were detected by staining with fluorescent antibodies against CD31. We showed that Gelfoam(®) implanted in transgenic mice expressing the nestin promoter-driven green fluorescent protein (ND-GFP mice) was rapidly vascularized with ND-GFP-expressing nascent blood vessels. Angiogenesis in the Gelfoam(®) was quantified by measuring the total length of ND-GFP-expressing nascent blood vessels in a skin flap by in vivo fluorescence microscopy imaging. The ND-GFP-expressing nascent blood vessels formed a network on the surface of the basic fibroblast growth factor (bFGF)-treated Gelfoam(®). We then developed a color-coded imaging model that can visualize the interaction between αv integrin linked to green fluorescent protein (GFP) in osteosarcoma cells and blood vessels in Gelfoam(®) vascularized after implantation in red fluorescent protein (RFP) transgenic nude mice. The implanted Gelfoam(®) became highly vascularized with RFP-expressing vessels in 14 days. 143B osteosarcoma cells expressing αv integrin-GFP were injected into the Gelfoam(®) after transplantation of Gelfoam(®). After cancer cell injection, cancer cells interacting with blood vessels were observed in the Gelfoam(®) by color-coded confocal microscopy through the skin flap window. We developed another color-coded Gelfoam(®)-based imaging model that can visualize the anastomosis between blood vessels. RFP-expressing vessels in vascularized Gelfoam(®), previously transplanted into RFP transgenic mice, were re-transplanted into ND-GFP mice. Skin flaps were made and anastomosis between the GFP-expressing nascent blood vessels of ND-GFP transgenic nude mice and RFP blood vessels in the transplanted Gelfoam(®) could be imaged. Our results demonstrate that the Gelfoam(®) in vivo angiogenesis model in combination with fluorescent protein labeling of blood vessels is a powerful system for use in the discovery and evaluation of agents influencing vascularization.

Topical nonsteroidal anti-inflammatory drugs for macular edema

Nonsteroidal anti-inflammatory drugs (NSAIDs) are nowadays widely used in ophthalmology to reduce eye inflammation, pain, and cystoid macular edema associated with cataract surgery. Recently, new topical NSAIDs have been approved for topical ophthalmic use, allowing for greater drug penetration into the vitreous. Hence, new therapeutic effects can be achieved, such as reduction of exudation secondary to age-related macular degeneration or diabetic maculopathy. We provide an updated review on the clinical use of NSAIDs for retinal diseases, with a focus on the potential future applications.

Treatments for corneal neovascularization: a review

Corneal neovascularization (CNV) may be a physiological response to various stimuli, but a chronic and persistent upregulation of neoangiogenesis can result in pathological CNV. Pathological blood vessels are immature and lack structural integrity, predisposing the cornea to lipid exudation, inflammation, and scarring. CNV can therefore become a potentially blinding condition. In this review, we frame CNV in an epidemiological perspective, consider risk factors for CNV, provide an overview of CNV pathogenesis, and consider the impact of CNV on corneal transplantation. We consider treatments that are of largely historical interest, before reviewing contemporary medical and surgical treatments. Within medical treatments, we report on steroids, nonsteroidal anti-inflammatory agents, antivascular endothelial growth factor agents, and cyclosporine. Within surgical treatments, we report on the use of lasers, photodynamic therapy, superficial keratectomy, and diathermy/cautery-based treatments.

Nestin-driven green fluorescent protein as an imaging marker for nascent blood vessels in mouse models of cancer

A transgenic mouse, in which the regulatory elements of the stem cell marker, nestin drive green fluorescent protein (ND-GFP), expresses GFP in nascent blood vessels. Red fluorescent protein (RFP)-expressing tumors transplanted to nestin-GFP mice enable specific visualization of nascent vessels in the growing tumors. The ND-GFP mouse was also utilized to develop a rapid in vivo/ex vivo fluorescent angiogenesis assay by implanting Gelfoam(®), a surgical sponge derived from pigskin, which was rapidly vascularized by fluorescent nascent blood vessels. Angiogenesis could be imaged and quantified when stimulated or inhibited by specific compounds in both tumors and Gelfoam(®). These fluorescent models can be used to study the early events of angiogenesis and to quantitatively determine efficacy of antiangiogenesis compounds.

Nonsteroidal anti-inflammatory drugs in ophthalmology

Nonsteroidal anti-inflammatory drugs (NSAIDs) are increasingly employed in ophthalmology to reduce miosis and inflammation, manage scleritis, and prevent and treat cystoid macular edema associated with cataract surgery. In addition, they may decrease postoperative pain and photophobia associated with refractive surgery and may reduce the itching associated with allergic conjunctivitis. In recent years, the U.S. Food and Drug Administration has approved new topical NSAIDs, and previously approved NSAIDs have been reformulated. These additions and changes result in different pharmacokinetics and dosing intervals, which may offer therapeutic advantages. For example, therapeutic effects on diabetic retinopathy and age-related macular degeneration may now be achievable. We provide an updated review on NSAIDs and a summary of their current uses in ophthalmology with attention to potential future applications.

Cortisone, heparin and argon laser in the treatment of corneal neovascularization

Chemical burns and contact lenses can induce corneal neovascularization. The pathogenic mechanisms of angiogenesis are not well understood. A heparin-cortisone combination has been shown to inhibit traumatic angiogenesis and argon laser photocoagulation has been useful in the treatment of corneal graft neovascularization. We describe three patients treated for corneal neovascularization with these methods. Tear fluid plasmin levels were also monitored. The corneal neovascularization was caused by contact lens use in two patients, and by a severe chemical burn in one patient. Subconjunctival cortisone injections proved to be efficient in the treatment of the contact lens induced corneal neovascularization. Corneal argon laser photocoagulation seemed to have an additional effect. The role of topical heparin remained unclear. The tear fluid plasmin levels were not significantly elevated.

Corneal transparency: genesis, maintenance and dysfunction

Optimal vision is contingent upon transparency of the cornea. Corneal neovascularization, trauma and, surgical procedures such as photorefractive keratectomy and graft rejection after penetrating keratoplasty can lead to corneal opacification. In this article we identify the underlying basis of corneal transparency and factors that compromise the integrity of the cornea. With evidence from work on animal models and clinical studies, we explore the molecular mechanisms of both corneal avascularity and its dysfunction. We also seek to review therapeutic regimens that can safely salvage and restore corneal transparency.

Dual-color imaging of tumor angiogenesis

Angiogenesis is a critical step in the process of tumor metastasis. Many models have been used to study this process, but they have been artificial and do not reflect the actual process that takes place in the human being. Our laboratory has developed realistic models of angiogenesis based on orthotopic transplantation of human tumors in mice. In order to make angiogenesis visible in real time, our laboratory has developed mouse models in which the blood vessels are labeled with green fluorescent protein (GFP) such that they can be visualized by vascularizing tumors expressing red fluorescent protein (RFP). A particularly valuable model is a nude mouse in which the promoter from the stem-cell-marker protein, nestin, drives the expression of GFP. In such transgenic mice, the nascent blood vessels, in contrast to the mature blood vessels, express GFP. This model, in which human tumors expressing RFP are implanted, has been used to test drugs for their antitumor and antiangiogenetic activity. We have observed for the first time the high antiangiogenetic efficacy of cancer drugs such as gemcitabine and doxorubicin. These models should prove very valuable in the discovery of new antiangiogenesis drugs.

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.

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.

Chapter 2. Color-coded fluorescent mouse models of cancer cell interactions with blood vessels and lymphatics

Several new strategies now exist for imaging cancer cell interactions with both blood vessels and lymphatics in living animals. Tumors labeled with fluorescent proteins allow the nonluminous capillaries and larger blood vessels to be clearly visualized against the bright tumor fluorescence via either intravital or whole-body imaging. Signal attenuation by overlying tissue can be markedly reduced by opening a reversible skin flap in the light path, increasing detection sensitivity. With this increase in observable depth of tissue, many previously obscured small tumor vessels can be imaged. In addition, dual-color fluorescence imaging, effected by using red fluorescent protein (RFP)-expressing tumors growing in green fluorescent protein (GFP)-expressing transgenic mice, can show with great clarity tumor-stroma interactions, including the developing tumor vasculature. The GFP-expressing host vasculature, both mature and nascent, can be distinguished from the RFP-expressing tumor itself in this model. Transgenic mice with GFP gene expression driven by the nestin promoter offer another way to image the developing tumor vasculature. In this model system, only nascent blood vessels express GFP, allowing newly developing blood vessels to be imaged against a background of RFP-expressing tumor cells. Finally, dual-color imaging technology can facilitate the imaging of cancer cell interactions with lymphatics. Delivery of FITC-dextran or fluorescent antibodies specific for lymphatic endothelium to the lymphatics around an RFP-expressing tumor allows imaging of tumor cell shedding into the lymphatic system. This imaging technology has the potential to visualize each step of tumor progress.

Dual-color imaging of angiogenesis and its inhibition in bone and soft tissue sarcoma

BACKGROUND

Angiogenesis is a critical step in tumor growth, progression, and metastasis. Soft tissue and bone sarcoma are resistant to most therapeutic approaches. Angiogenesis of these tumors may be an effective target. We hypothesized that we could inhibit tumor growth by targeting angiogenesis in a mouse model of sarcoma. We demonstrate in this report, using powerful color-coded fluorescent imageable tumor-host models, the onset of angiogenesis of these sarcomas and its inhibition.

MATERIALS AND METHODS

Transgenic mice were used as the host in which green fluorescent protein (GFP) is driven by a regulatory element of the stem cell marker nestin (ND-GFP). Nascent blood vessels express ND-GFP in this model. We visualized, by dual-color fluorescence imaging, angiogenesis of sarcoma formed by the HT-1080 human fibrosarcoma cell line expressing red fluorescent protein (RFP) in the ND-GFP mice. Tumor cells were injected into either the muscle or the bone.

RESULTS

Nestin was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing tumors, including the surrounding tissues. Immunohistochemical staining showed that CD31 colocalized in ND-GFP-expressing nascent blood vessels. The density of nascent blood vessels in the tumor was readily quantitated. The mice were given daily i.p. injections of 5 mg/kg of doxorubicin after implantation of tumor cells. Doxorubicin significantly decreased the mean nascent blood vessel density in the tumors as well as decreased tumor volume.

CONCLUSION

The dual-color model of the ND-GFP nude mouse and RFP sarcoma cells is useful for the visualization and quantitation of bone and soft tissue tumor angiogenesis and evaluation of angiogenic inhibitors for such tumors. These data suggest targeting angiogenesis of sarcomas as a promising clinical approach.

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.

Mesenchymal stem cell transplantation in a rabbit corneal alkali burn model: engraftment and involvement in wound healing

PURPOSE

To investigate whether systemically transplanted mesenchymal stem cells (MSCs) can home and engraft in tissue to promote cornea wound healing after alkali burn, as a new source for treatment.

METHODS

Corneal alkali burn was created in four group rabbits: Group I, normal bone marrow function, without MSCs transplantation; Group II, normal bone marrow function, with MSCs transplantation; Group III, bone marrow suppressed by cyclophosphamide, without MSCs; Group IV, bone marrow suppressed by cyclophosphamide, with MSCs. Clinical outcome was evaluated by cornea re-epithelization, cornea opacity, and neovascularization. Cell engraftment into bone marrow, circulation, and cornea was monitored. Immunohistochemistry, using proliferating cell nuclear antigen (PCNA), P63, vimentin, and alpha-smooth muscle actin (alpha-SMA) was carried out to assess the cell proliferative and differentiative ability.

RESULTS

At the time of 1-month follow-up, Group II rabbits showed the best clinical results with a clearer healed cornea compared with other groups. Well-formed neovascularization appeared on day 14 after alkali burn in Group II, that coincided with the maximum engraftment of MSCs. PCNA, P63, vimentin were more strongly expressed in Group II at multiple time points. DiI-labelled MSCs were differentiated into myofibroblast by the expression of alpha-SMA. Delayed and insufficient cell engraftment, with malformed neovascularization and retarded corneal wound healing was found in Groups III and IV.

CONCLUSIONS

Systemically transplanted MSCs can engraft to injured cornea to promote wound healing, by differentiation, proliferation, and synergizing with haemotopoietic stem cells.

Inhibitory effect of triamcinolone acetonide on corneal neovascularization

BACKGROUND

Corneal neovascularization (NV) plays an important role in the pathogenesis of corneal disorders. Recently, triamcinolone acetonide (TA) has been reported as a potential treatment for ocular angiogenesis. However, there are no reports on the inhibitory effect of TA on the corneal NV.

METHODS

Triamcinolone acetonide (2 mg) was administered to four rabbits' eyes by a subconjunctival injection immediately after a basic fibroblast growth factor (bFGF)-pellet was placed into the cornea. As a control, four eyes received an injection of distilled water. Four weeks later, the inhibition of corneal NV was evaluated as the percentage ratio of the vessel invasion area to the area that was sandwiched between the pellet and the limbus cornea. To identify the characteristic appearance of new corneal vessels, the control cornea was examined by using the antibody of vascular endothelial growth factor (VEGF). To confirm TA concentration in TA-treated corneas, the TA level was measured using high-performance liquid chromatography.

RESULTS

Neovascularization from the limbus to the pellet was detected in control eyes 4 weeks after the bFGF pellet implantation. TA-treated eyes demonstrated the inhibition of the neovascular response to the pellet. The severity of NV as compared between control and TA-treated eyes was statistically significant (P<0.05). Morphologically, new vessel growth was shown in the control cornea, and endothelial cells of new vessels were positively stained with the antibody of VEGF. TA concentration in TA-treated corneas at 2 weeks showed 63.5+/-42.8 microg/g (n=4, mean +/- SD), while TA was not detected in control and TA-treated corneas at 4 weeks. The level of TA was effectively maintained for at least 2 weeks after the subconjunctival injection.

CONCLUSION

We have demonstrated that subconjunctival TA administration inhibited rabbit corneal NV. This agent may prove useful in the treatment of corneal angiogenic disorders.

Imaging tumor angiogenesis with fluorescent proteins

We have developed three unique mouse models to image angiogenesis with fluorescent proteins, which are described in this review. First, we have adapted the surgical orthotopic implantation (SOI) model to image angiogenesis of human tumors labeled with green fluorescent protein (GFP) transplanted in nude mice. The nonluminous induced capillaries are clearly visible by contrast against the very bright tumor fluorescence examined either intravitally or by whole-body imaging in real time. Intravital images of an SOI model of human pancreatic tumors expressing GFP visualized angiogenic capillaries at both primary and metastatic sites. Whole-body optical imaging showed that blood vessel density increased linearly over a 20-week period in an SOI model of human breast cancer expressing GFP. Opening a reversible skin-flap in the light path markedly reduces signal attenuation, increasing detection sensitivity many-fold and enabling vessels to be externally visualized in GFP-expressing tumors growing on internal organs. The second model utilizes dual-color fluorescence imaging, effected by using red fluorescent protein (RFP)-expressing tumors growing in GFP-expressing transgenic mice that express GFP in all cells. This dual-color model visualizes with great clarity the details of the tumor-stroma interaction, especially tumor-induced angiogenesis. The GFP-expressing tumor vasculature, both nascent and mature, are readily distinguished interacting with the RFP-expressing tumor cells. Using a spectral imaging system based on liquid crystal tunable filters, we were able to separate individual spectral species on a pixel-by-pixel basis. Such techniques non-invasively visualized the presence of host GFP-expressing vessels within an RFP-labeled orthotopic human breast tumor by real-time whole-body imaging. The third model involves a transgenic mouse in which the regulatory elements of the stem cell marker nestin drive GFP. The nestin-GFP mouse expresses GFP in areas of the brain, hair follicle stem cells, and in a network of blood vessels in the skin interconnecting hair follicles. RFP-expressing tumors transplanted to nestin-GFP mice enable specific visualization of nascent vessels in skin-growing tumors such as melanoma. Thus, fluorescent proteins expressed in vivo offer very high resolution and sensitivity for real-time imaging of angiogenesis.

Ocular neovascularization: a valuable model system

There is no unique formula for angiogenesis. Instead there is a large group of potential participating proteins that interact in complex ways. Depending upon the surrounding cell types and the relative expression levels of angiogenesis-related proteins, the 'angiogenesis cascade' can vary. Therefore, it is valuable to study and compare the role of proteins in several well-characterized vascular beds. The eye provides a useful model system, because it contains several vascular beds sandwiched between avascular tissue. This allows for unequivocal identification and quantitation of new vessels. Retina-specific promoters combined with inducible promoter systems provide a means to regulate the expression of proteins of interest. As a relatively isolated compartment, the eye also provides advantages for gene transfer. By gaining insight regarding the molecular signals involved in various types of ocular angiogenesis, general concepts can emerge that may apply to other settings, including tumor angiogenesis. One concept that has emerged is that despite participation of multiple stimulatory factors for ocular neovascularization, VEGF plays an essential role and interruption of VEGF signaling is an important therapeutic strategy. Another concept is that while most studies have focused on prevention of ocular neovascularization, regression of new vessels is desirable and is achievable with at least three agents, combretastatin A-4 phosphate, pigment epithelium-derived factor, and angiopoietin-2. Finally, endostatin and angiostatin, which have been sources of controversy because of inconsistent results in tumor models, have been shown to have good efficacy when delivered by gene transfer in models of ocular neovascularization. These results provide leads for new ocular treatments and perspective for evaluation of studies of neovascularization in extraocular tissues.

Whole-body and intravital optical imaging of angiogenesis in orthotopically implanted tumors

The development of drugs for the control of tumor angiogenesis requires a simple, accurate, and economical assay for tumor-induced vascularization. We have adapted the orthotopic implantation model to angiogenesis measurement by using human tumors labeled with Aequorea victoria green fluorescent protein for grafting into nude mice. The nonluminous induced capillaries are clearly visible against the very bright tumor fluorescence examined either intravitally or by whole-body luminance in real time. The orthotopic implantation model of human cancer has been well characterized, and fluorescence shadowing replaces the laborious histological techniques for determining blood vessel density. Intravital images of orthotopically implanted human pancreatic tumors clearly show angiogenic capillaries at both primary and metastatic sites. A quantitative time course of angiogenesis was determined for an orthotopically growing human prostate tumor periodically imaged intravitally in a single nude mouse over a 19-day period. Whole-body optical imaging of tumor angiogenesis was demonstrated by injecting fluorescent Lewis lung carcinoma cells into the s.c. site of the footpad of nude mice. The footpad is relatively transparent, with comparatively few resident blood vessels, allowing quantitative imaging of tumor angiogenesis in the intact animal. Capillary density increased linearly over a 10-day period as determined by whole-body imaging. Similarly, the green fluorescent protein-expressing human breast tumor MDA-MB-435 was orthotopically transplanted to the mouse fat pad, where whole-body optical imaging showed that blood vessel density increased linearly over a 20-week period. These powerful and clinically relevant angiogenesis mouse models can be used for real-time in vivo evaluation of agents inhibiting or promoting tumor angiogenesis in physiological microenvironments.

Microvascular effects of selective prostaglandin analogues in the eye with special reference to latanoprost and glaucoma treatment

Prostaglandin F(2alpha) analogues have recently been introduced on the market for glaucoma treatment. While these drugs have a well-documented intraocular pressure reducing effect only a limited number of studies have been published regarding their effects on the microvasculature in the eye. Since many naturally occurring prostaglandins have marked effects on the cardiovascular system it is conceivable that synthetic prostaglandins used as glaucoma drugs may exert microvascular effects in the eye, even if they exhibit receptor selectivity. Latanoprost, the active principle of Xalatan((R)) eye drops, is a selective FP prostanoid receptor agonist, and much of the paper is focused on the microvascular effects of latanoprost and some closely related prostaglandin analogues. The purpose of the paper is to review the literature on the microvascular effects of prostaglandins in the eye, and to present some unpublished data on the effects of selective prostaglandin analogues. Most of the prostaglandin analogues studied exhibit selectivity for the FP prostanoid receptor. Results from studies with the following prostaglandin analogues are presented in the paper: PGF(2alpha)-isopropyl ester (PGF(2alpha)-IE), 17-phenyl-18,19,20-trinor-PGF(2alpha)-isopropyl ester (17-phenyl-PGF(2a)-IE), 15-keto-17-phenyl-18,19, 20-trinor-PGF(2alpha)-isopropyl ester (15-keto-17-phenyl-PGF(2a)-IE), 13,14-dihydro-17-phenyl-18,19,20-trinor-PGF(2alpha)-isopropy l ester (latanoprost), 13,14-dihydro-15R,S-17-phenyl-18,19, 20-trinor-PGF(2alpha)-isopropyl ester (PhXA34), 17-phenyl-18,19, 20-trinor-PGE(2)-isopropyl ester (17-phenyl-PGE(2)-IE), and 19R-hydroxy-PGE(2) (19R-OH-PGE(2)). The regional blood flow has been determined with radioactively labelled microspheres, the blood volume with (51)Cr labelled erythrocytes and the capillary permeability to albumin with (125)I and (131)I labelled albumin. PGF(2alpha)-IE has been shown to exert marked microvascular effects in the rabbit anterior segment including vasodilatation, increased capillary permeability, and a breakdown of the blood-aqueous barrier. 17-phenyl-PGF(2alpha)-IE, 15-keto-17-phenyl-PGF(2alpha)-IE, and PhXA34/latanoprost exerted significantly less vasodilatory effect, and little effect on capillary permeability was seen with the FP receptor agonists when studied with Evans blue. Intravenous administration of PhXA34 at a dose range of 1-100 microg/kg b.w. had no consistent effect on the regional blood flow in the eye indicating that FP receptors in the ocular blood vessels are not expressed in the rabbit, or alternatively are not functionally coupled to regulation of vascular tone. In cats topical application of PGF(2alpha)-IE had no significant effect the on the regional blood flow in cannulated eyes. No blood flow experiments were performed in intact eyes with PGF(2alpha)-IE. 17-phenyl-PGF(2alpha)-IE and latanoprost caused some vasodilation in the anterior segment. None of the analogues had any significant effect on the blood volume in the ocular tissues, but an increase in capillary permeability to albumin was seen in several tissues of the eye. However, in the eyelid, nictitating membrane and conjunctiva exposed to high concentrations of the prostaglandins no or only little leakage of albumin was detected. It appears that the intraocular microvasculature in the cat exhibits some sensitivity to FP prostanoid receptor agonists. (ABSTRACT TRUNCATED)

Inhibitory effects of plasminogen fragment on experimentally induced neovascularization of rat corneas

BACKGROUND

Corneal neovascularization plays an important role in the pathogenesis of a number of corneal disorders. Recently a polypeptide was demonstrated, generated by the primary tumor, that inhibited angiogenesis and growth in metastases. This polypeptide is similar to a 38-kDa plasminogen fragment.

METHODS

We surgically implanted into rat corneal stroma a slow-release ethylene-vinyl-acetate (EVA) copolymer pellet containing basic fibroblast growth factor (bFGF) to induce corneal neovascularization. Then we applied aqueous solution containing plasminogen fragment to the rat cornea in order to observe the degree of inhibition of angiogenesis.

RESULTS

In the eyes of control rats, neovascularization from the limbus to the pellet occurred, graded 4+ in all five animals. In plasminogen fragment-treated rats, there was virtually complete inhibition of the neovascular response to the pellet. Of five treated rats, three showed no neovascularization and two demonstrated grade 1+ neovascularization. The difference in the degree of neovascularization between control and plasminogen fragment treatment was statistically significant (P < 0.05).

CONCLUSION

Our studies provide the first direct evidence that rat corneal neovascularization is inhibited by instillation of plasminogen fragment. This agent may prove useful in the treatment of corneal angiogenic disorder.

Increased synthesis of specific eicosanoids in rejected corneal grafts

PURPOSE

Corneal injury stimulates the formation of both prostaglandins (PG) and 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), the major lipoxygenase metabolite. The purpose of this study was to investigate the metabolism of arachidonic acid (AA) in a model of corneal graft rejection.

METHODS

Corneal tissue from Dutch belted rabbits was transplanted to vascularized corneas of New Zealand white rabbits. Rejected corneas were removed at the endstage of allograft failure. The allograft, the host corneal rim, the contralateral control cornea rim of equal size and normal Dutch belted cornea from the same site as the allograft were incubated with 0.25 microCi [3H]AA and the released eicosanoids were analyzed by high-performance liquid chromatography.

RESULTS

The host corneal rims, adjacent to the failed allografts, produced up to five times as much 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) as contralateral control corneal rims. Additionally, prostaglandin E2 (PGE2) formation in the host rims increased 100% above controls, and 12(S)-HETE and PGE2 synthesis in the rejected corneal graft also increased. 12(R)-HETrE, an endogenous corneal angiogenic factor, was not detected in rejected corneas.

CONCLUSIONS

The results point to the importance of selective AA pathways as the source key inflammatory components found in rejected allografts.

Experimental corneal neovascularisation using sucralfate and basic fibroblast growth factor

PURPOSE

To develop a non-inflammatory model of both acute and chronic angiogenesis in the rabbit cornea using a known directly angiogenic cytokine.

METHODS

Pellets made of the slow-release polymer Hydron (polyhydroxyethylmethacrylate) and containing sucralfate and/or basic fibroblast growth factor (basic-FGF) were implanted into rabbit corneas. The neovascular response to the implantation of pellets containing basic-FGF alone, sucralfate alone or a titration of basic-FGF in the presence of a constant amount of sucralfate was measured. The role of inflammation in the neovascular response was also investigated.

RESULTS

The addition of sucralfate to the pellets led to the sustained release of basic-FGF resulting in a predictable and aggressive neovascular response with a low dose of basic-FGF that by itself was unable to elicit neovascularisation. At a dose of 500 ng per pellet, approximately one-third of the surface area of the cornea was vascularised within eight days of implantation. Minimal or no vascularisation occurred with the same dose of basic-FGF without sucralfate. While this dose of basic-FGF induced corneal oedema, only minimal inflammation was observed and the response was unaffected by ionising radiation. A less aggressive though still robust neovascular response with no or only minimal oedema was observed when the dose was lowered to 50 ng of basic-FGF per pellet. Some induced vessels persisted for more than three months.

CONCLUSION

This is an inexpensive in vivo model of angiogenesis with the advantages of the neovascularisation being aggressive, predictable, persistent, unassociated with an obvious inflammatory response and induced by the sustained release of an agent known to have a direct stimulatory action on endothelial cells.

Quantitative analysis of angiogenesis and growth of bone: effect of indomethacin exposure in a combined in vitro-in vivo approach

Nonsteroidal anti-inflammatory agents have been used experimentally and clinically to suppress a variety of physiological events, including angiogenesis and formation of bone. The exact mechanisms by which indomethacin alters skeletal tissue generation are unknown, due in part to methodological limitations. By the use of an organ culture assay and an animal model using intravital microscopy in mice bearing dorsal skinfold chambers, the effect of indomethacin on growth and angiogenesis of neonatal femora was characterized over 16 days. In both assays, femora significantly elongated with time (P < 0.05). The in vitro growth rate was more rapid than in vivo and dependent on the serum concentration, culture medium and age of mice. Although enhancing the serum content promoted cellular proliferation in organ culture, it dose-dependently suppressed femoral elongation, leading at 20% fetal calf serum to growth rates identical to those observed in vivo. Indomethacin supplementation (2 and 10 mg l-1) significantly accelerated longitudinal femoral growth in organ culture (P < 0.05), whereas in vivo indomethacin (2 mg kg-1) did not modulate either angiogenesis or elongation of bone. Our in vitro data propose a central role of serum in the regulation of bone formation. Although indomethacin altered femoral growth in vitro, our findings do not suggest that indomethacin suppresses angiogenesis or growth of bone in vivo. The complexity of physiological events in vivo may be obscuring a detectable effect.

Angiostasis and vascular regression in chronic granulomatous inflammation induced by diclofenac in combination with hyaluronan in mice

Angiostasis and vascular regression in chronic granulomatous inflammation was assessed in mice induced with diclofenac in combination with hyaluronan. The local injection of 0.1 mL HYAL EX-0001 (0.18% diclofenac in 2.5% hyaluronan) reduced granulomatous development after six days treatment from 150.4 +/- 13.8 (0.18 saline) to 117.1 +/- 17.8 mg (dry weight, n = 10), but not significantly when compared with 0.1 mL 2.5% hyaluronan alone or diclofenac in 0.1 mL saline. Diclofenac administered in saline had no significant effect when compared with saline control. The vascular density, expressed as carmine content per mg dry weight tissue, in those animals treated with HYAL EX-0001 was also significantly reduced to 5.27 +/- 0.55 micrograms mg-1 (P < 0.1, n = 10) when compared with saline control (7.99 +/- 1.0), hyaluronan alone (7.20 +/- 1.0), and diclofenac in saline. (7.36 +/- 1.28). A similar profile of activity was seen on topical application except that all treatments did not affect granulomatous tissue development. On therapeutic dosing of mice daily with HYAL EX-0001 from day 7 after induction of the granulomatous tissue, the granulomatous tissue development was dramatically reduced from 111.67 +/- 4.40 mg (n = 14 on day 7) to 60.23 +/- 7.22 (P < 0.001, n = 8 on day 14) and 54.98 +/- 7.88 (P < 0.001, n = 8 on day 21). HYAL EX-0001 after 14 days of application significantly reduced granulomatous tissue mass when compared with the hyaluronan-dosed control on day 21 (89.58 +/- 7.49, P = 0.01, n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of low molecular weight heparan sulphate on angiogenesis in the rat cornea after chemical cauterization

Vascularization of the cornea occurs in many pathological conditions and can result in loss of visual acuity. It is also thought that vascularization predisposes the cornea to reject grafts by facilitating the detection of foreign antigens in donor material. A rat corneal assay for angiogenesis was adopted in the present study to evaluate the possible angiostatic activity of a low molecular weight heparan sulphate (LMW-HS). Corneal lesions were induced by chemical cauterization at 2 mm from the corneoscleral limbus. Rats were randomized to receive two drops/eye four times daily, for 6 days, of a solution of LMW-HS in vehicle (2.5% carboxymethylcellulose), heparin, heparin plus hydrocortisone, or vehicle alone. After a 6 day-treatment period, the eyes were perfused with india ink and the degree of neovascularization was evaluated. In rats treated with vehicle alone a dense vascular network extending from the corneoscleral limbus to the cauterized site was observed; on the contrary, a markedly reduced vascular network was evidenced in animals treated with LMW-HS. The distribution of basic fibroblast growth factor (bFGF) in the cauterized cornea was also evaluated by using an immunohistochemical method. A marked bFGF immunoreactivity was demonstrated in corneal epithelium and stroma of control rats 12-48 hours after the cautery. These results lead to the assumption that LMW-HS could be used in ophthalmology to inhibit corneal neovascularization.

Laser photocoagulation of experimental corneal stromal vascularization. Efficacy and histopathology

BACKGROUND

Conventional treatment of corneal stromal vascularization is often inadequate. The authors developed a rabbit model of corneal stromal vascularization, treated it with laser photocoagulation, and then studied the histopathology.

METHODS

A reproducible model of corneal stromal vascularization was developed in albino rabbits by injecting sodium hydroxide into the corneal stroma. Corneal stromal vascularization was produced in both eyes of 13 rabbits, and treated after stabilization at 5 weeks with 577-nm yellow dye laser in 1 eye of each rabbit. Seven rabbits were followed for 6 months with corneal angiography and photography, and the corneal stromal vascularization quantified with a grid. The other 6 rabbits were killed at 1, 4, 8, 24, 48 hours, and 6 days after laser photocoagulation and examined by light and transmission electron microscopy.

RESULTS

Stable corneal stromal vascularization was observed in the anterior and midstroma for at least 6 months in the model. Laser photocoagulation reduced corneal stromal vascularization significantly compared with the controls (P < or = 0.05), resulting in 40.7% +/- 5.0%, 45.3% +/- 3.3%, and 34.9% +/- 5.2% (mean +/- standard error of the mean) reduction at 2, 4, and 6 months, respectively. Maximum inflammatory cell infiltrates were detected at 8 hours after laser photocoagulation, which diminished markedly at 6 days. The stroma of unlasered eyes showed no inflammatory cells and considerably more patent blood vessels than the lasered eyes. In the lasered eyes, transmission electron microscopy showed damaged vascular endothelial cells, extravasated erythrocytes, haphazardly arranged collagen fibrils, thrombus formation, and ghost vessels in the stroma. No damage was observed in the deep corneal stroma or endothelium in the lasered eyes.

CONCLUSION

Laser photocoagulation is effective in reducing corneal stromal vascularization in this model for at least 6 months. It does not damage the deeper stroma or endothelium.

Modulation of immunogenic keratitis in rabbits by topical administration of inhibitors of lipoxygenase and cyclooxygenase

Intrastromal injection with human serum albumin (HSA) in the rabbit cornea induced edema and a ring-shaped leukocyte infiltrate followed by neovascularization. The effect of topically administered lipoxygenase and cyclooxygenase inhibitors on this inflammatory keratitis was studied. The lipoxygenase inhibitors Bay 08276 and Rev 5901 and the cyclooxygenase inhibitor suprofen were given as 1% eye drops three times daily during the experiment. In eyes treated with lipoxygenase inhibitors leukocyte infiltration, neovascularization and edema formation decreased. In eyes treated with a cyclooxygenase inhibitor the period of neovascularization was slightly shortened and corneal edema decreased. No influence on leukocyte infiltration was seen.

Differential effects of leukotrienes B4 and C4 on bovine aortic endothelial cell proliferation in vitro

The effect of leukotrienes derivated from arachidonic acid was studied on vascular endothelium proliferation. The peptido-leukotriene LTC4 (0.1 nM - 0.1 microM) promoted a dose-dependent growth of bovine aortic endothelial cells in culture with a maximal effect at 10 nM. This proliferative activity could be receptor-mediated since LTC4 specifically bound to endothelial cell membranes with a Kd value of 50 nM. The leukotriene B4 did not induce any significant proliferation in the same range of concentrations. This result was consistent with the lack of LTB4 specific binding sites. This data suggests that LTC4 could be one of the factors implicated in angiogenesis during inflammatory processes.

Effect of indomethacin on immunogenic keratitis

The effect of topically administrated indomethacin was studied in rabbits on an experimentally provoked inflammatory keratitis. Intrastromal injection with horse serum induced in the cornea a ring-shaped infiltration with leukocytes and neovascularization. Indomethacin was given as eye drops three times daily during the experiment. In the indomethacin treated eyes leukocyte infiltration was prolonged but not the concomitant neovascularization. The potentiation of the leukocyte response may be due to a facilitation of chemotactic lipoxygenase products.

Topical indomethacin effect on neovascularisation of the cornea and on prostaglandin E2 levels

The effect of indomethacin 1% drops against a placebo (NaCl 0.9% solution) was tested in rabbits' corneas injured by a standardized chemical burn. The corneas treated with indomethacin 1% had less neovascularisation and a much smaller increase in the PGE2 levels as compared with the control fellow eyes treated with a placebo. It appears that indomethacin 1% drops have a clear effect on the inflammatory response of the cornea and deserve a clinical trial in selected patients suffering from corneal inflammatory changes.

Inhibitors of prostaglandin synthesis and the cornea

Low doses of indomethacin were applied topically to rabbit eyes in an experimental model of immunologically provoked inflammatory keratitis. Leucocyte infiltration was potentiated but not the concomitant neovascularization.

On the reactivity of corneal collagen and subcomponent C1q of the complement system with human platelets and IgG-coated latex particles

Collagen was isolated from bovine cornea and tested for reactivity towards platelets and IgG-coated polystyrene latex particles. The corneal collagen caused a dose- and temperature-dependent platelet aggregation in all human platelet-rich plasmas studied. As little as 0 . 31 micrograms of purified corneal collagen could trigger platelet activation. Human C1q, a subcomponent of the first complement component (C1), which shares extensive chemical-structural similarities with collagen, was able to inhibit the platelet aggregation provoked by corneal collagen. This blocking effect could be, however, overcome by increasing collagen doses. In a slide method or in aggregometry both corneal collagen and C1q agglutinated IgG-coated latex particles in a dose-dependent manner. Addition of such latex particles to platelet-rich plasmas or preincubation of the particles with collagen reduced or prevented the platelet action of collagen, suggesting that due to their reactivity with collagen immune complexes may play an inhibitory role in collagen-caused platelet aggregation. The results are discussed in relation to pathological events that lead to collagenolysis and also with respect to wound healing in the injured cornea.

Flurbiprofen in the treatment of corneal neovascularization induced by contact lenses

Cellulose acetate butyrate extended-wear contact lenses were fitted bilaterally on ten New Zealand albino rabbits. We administered flurbiprofen 0.03% solution topically to the experimental eyes and vehicle solution to the contralateral control eyes four times a day in a random, masked fashion beginning 24 hours before the contact lens was fitted. Corneal neovascularization, which developed in all eyes by the 25th day of contact lens wear, was significantly suppressed by flurbiprofen treatment (mean vessel length was 1.5 +/- 0.4 mm for the treated eyes and 3.0 +/- 0.3 mm for the control eyes; P less than .005). Topical administration of a noncorticosteroidal anti-inflammatory agent may be an effective treatment for corneal neovascularization induced by contact lenses.