Matrix revolution: molecular mechanism for inflammatory corneal neovascularization and restoration of corneal avascularity by epithelial stem cell transplantation

Anti-angiogenic biomolecules in neovascular age-related macular degeneration; therapeutics and drug delivery systems

Blindness in the elderly is often caused by age-related macular degeneration (AMD). The advanced type of AMD known as neovascular AMD (nAMD) has been linked to being the predominant cause of visual impairment in these people. Multiple neovascular structures including choroidal neovascular (CNV) membranes, fluid exudation, hemorrhages, and subretinal fibrosis, are diagnostic of nAMD. These pathological alterations ultimately lead to anatomical and visual loss. It is known that vascular endothelial growth factor (VEGF), a type of proangiogenic factor, mediates the pathological process underlying nAMD. Therefore, various therapies have evolved to directly target the disease. In this review article, an attempt has been made to discuss general explanations about this disease, all common treatment methods based on anti-VEGF drugs, and the use of drug delivery systems in the treatment of AMD. Initially, the pathophysiology, angiogenesis, and different types of AMD were described. Then we described current treatments and future treatment prospects for AMD and outlined the advantages and disadvantages of each. In this context, we first examined the types of therapeutic biomolecules and anti-VEGF drugs that are used in the treatment of AMD. These biomolecules include aptamers, monoclonal antibodies, small interfering RNAs, microRNAs, peptides, fusion proteins, nanobodies, and other therapeutic biomolecules. Finally, we described drug delivery systems based on liposomes, nanomicelles, nanoemulsions, nanoparticles, cyclodextrin, dendrimers, and composite vehicles that are used in AMD therapy.

A SU6668 pure nanoparticle-based eyedrops: toward its high drug Accumulation and Long-time treatment for corneal neovascularization

Corneal neovascularization (CNV) is one of the common blinding factors worldwide, leading to reduced vision or even blindness. However, current treatments such as surgical intervention and anti-VEGF agent therapy still have some shortcomings or evoke some adverse effects. Recently, SU6668, an inhibitor targeting angiogenic tyrosine kinases, has demonstrated growth inhibition of neovascularization. But the hydrophobicity and low ocular bioavailability limit its application in cornea. Hereby, we proposed the preparation of SU6668 pure nanoparticles (NanoSU6668; size ~135 nm) using a super-stable pure-nanomedicine formulation technology (SPFT), which possessed uniform particle size and excellent aqueous dispersion at 1 mg/mL. Furthermore, mesenchymal stem cell membrane vesicle (MSCm) was coated on the surface of NanoSU6668, and then conjugated with TAT cell penetrating peptide, preparing multifunctional TAT-MSCm@NanoSU6668 (T-MNS). The T-MNS at a concentration of 200 µg/mL was treated for CNV via eye drops, and accumulated in blood vessels with a high targeting performance, resulting in elimination of blood vessels and recovery of cornea transparency after 4 days of treatment. Meanwhile, drug safety test confirmed that T-MNS did not cause any damage to cornea, retina and other eye tissues. In conclusion, the T-MNS eye drop had the potential to treat CNV effectively and safely in a low dosing frequency, which broke new ground for CNV theranostics.

In vitro and Ex vivo characterization of nanonized amniotic membrane particles: An untapped modality for ocular surface reconstruction

The pristine Human Amniotic Membrane (HAM) has portrayed outstanding potential as scaffold for ocular surface reconstruction and regeneration. However, in treatment procedures where the supporting membrane matrix of HAM is not obligatory and only the bioactive molecules are vital, the surgical practise of HAM grafting causes redundant trauma and economic burden to the patient. Hence, in our laboratory we have attempted to break down HAM to nanoscale particles and validate its potential as a competent ocular therapeutic agent; by conducting a comparative analysis between the fresh, lyophilized, micronized and Nanonized Amniotic Membrane (NAM) particles. Our results evidently showcased that the prepared NAM particles was <100 nm and the major biomolecules such as collagen and hyaluronic acid were well retained. Further, the NAM particles eluted significantly higher amounts of proteins and growth factors while maintaining its stability and isotonicity when stored at 4 °C. Its biostability was assayed in the presence of lysozyme enzyme. Its remarkable ability to promote cell proliferation in rabbit corneal cells and negative cytotoxicity is an added advantage for ocular application. The ocular biocompatibility of NAM, evaluated by the ex vivo assessment of corneal thickness, transparency, histopathology, immunohistochemistry and corneal permeability clearly indicated its suitability for ophthalmic applications.

Combined Anti-Angiogenic and Anti-Inflammatory Nanoformulation for Effective Treatment of Ocular Vascular Diseases

Background

Ocular vascular diseases are the major causes of visual impairment, which are characterized by retinal vascular dysfunction and robust inflammatory responses. Traditional anti-angiogenic or anti-inflammatory drugs still have limitations due to the short-acting effects. To improve the anti-angiogenic or anti-inflammatory efficiency, a dual-drug nanocomposite formulation was proposed for combined anti-angiogenic and anti-inflammatory treatment of ocular vascular diseases.

Methods 

CBC-MCC@hMSN(SM) complex nanoformulation was prepared by integrating conbercept (CBC, an anti-angiogenic drug) and MCC950 (MCC, an inhibitor of inflammation) into the surface-modified hollow mesoporous silica nanoparticles (hMSN(SM)). CBC-MCC@hMSN(SM) complex nanoformulation was then characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, zeta potentials, and nitrogen adsorption-desorption measurement. CBC and MCC release profile, cytotoxicity, tissue toxicity, anti-angiogenic effects, and anti-inflammatory effects of CBC-MCC@hMSN(SM) were estimated using the in vitro and in vivo experiments.

Results

 CBC-MCC@hMSN(SM) complex had no obvious cytotoxicity and tissue toxicity and did not cause a detectable ocular inflammatory responses. CBC-MCC@hMSN(SM) complex was more effective than free CBC or MCC in suppressing endothelial angiogenic effects and inflammatory responses in vitro. A single intraocular injection of CBC-MCC@hMSN(SM) complex potently suppressed diabetes-induced retinal vascular dysfunction, choroidal neovascularization, and inflammatory responses for up to 6 months.

Conclusion 

Combined CBC and MCC nanoformulation provides a promising strategy for sustained suppression of pathological angiogenesis and inflammatory responses to improve the treatment outcomes of ocular vascular diseases.

An Update on Novel Ocular Nanosystems with Possible Benefits in the Treatment of Corneal Neovascularization

Corneal neovascularization (CNV) is an ocular pathological change that results from an imbalance between angiogenic factors and antiangiogenic factors as a result of various ocular insults, including infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation. Current clinical strategies for the treatment of CNV include pharmacological treatment and surgical intervention. Despite some degree of success, the current treatment strategies are restricted by limited efficacy, adverse effects, and a short duration of action. Recently, gene-based antiangiogenic therapy has become an emerging strategy that has attracted considerable interest. However, potential complications with the use of viral vectors, such as potential genotoxicity resulting from long-term expression and nonspecific targeting, cannot be ignored. The use of ocular nanosystems (ONS) based on nanotechnology has emerged as a great advantage in ocular disease treatment during the last two decades. The potential functions of ONS range from nanocarriers, which deliver drugs and genes to target sites in the eye, to therapeutic agents themselves. Various preclinical studies conducted to date have demonstrated promising results of the use of ONS in the treatment of CNV. In this review, we provide an overview of CNV and its current therapeutic strategies and summarize the properties and applications of various ONS related to the treatment of CNV reported to date. Our goal is to provide a comprehensive review of these considerable advances in ONS in the field of CNV therapy over the past two decades to fill the gaps in previous related reports. Finally, we discuss existing challenges and future perspectives of the use of ONS in CNV therapy, with the goal of providing a theoretical contribution to facilitate future practical growth in the area.

Research models of sulfur mustard- and nitrogen mustard-induced ocular injuries and potential therapeutics

Sulfur mustard (SM) is a notorious, bifunctional alkylating vesicant that was first used in warfare during World War I in 1917 and since then has been deployed in numerous skirmishes with its most recent documented use being during the Middle Eastern conflicts. Apart from its use in combat and terrorist activities, continual threat of accidental exposure from old stockpiles and improperly discarded munitions is ever present, especially to the innocent and unassuming civilian populations. SM can cause devastating injuries, depending on the dosage of SM exposure, route of exposure, as well as the physiological conditions of the individuals exposed. The most common routes of exposure are ocular, dermal, and exposure to the lungs and respiratory tissues through inhalation. Eyes are the most susceptible organ to SM-induced toxicities owing to their high moisture content and rapidly dividing cells. Additionally, ocular injury causes the most expeditious disablement of individuals even upon whole-body exposures. Therefore, it is imperative to understand the mechanisms underlying SM-induced ocular toxicity and design therapeutic interventions to prevent/mitigate ocular injuries. Ocular SM exposure may cause a wide range of symptoms such as inflammation, lacrimation, itching, dryness, photophobia, edema of the cornea/sclera/retina/iris, conjunctivitis, degradation of the corneal layer, fusion of two or more ocular layers, neovascularization, fibrosis, and temporary or permanent structural damage to one or more ocular layers. These symptoms may lead to vision impairments, resulting in partial or complete blindness that may be permanent. The highly toxic and exceedingly notorious nature of SM makes it a highly regulated chemical, requiring very expensive licensing, security, and safety requirements; thus, the more easily accessible analogue, nitrogen mustard (NM) that mimics SM-induced toxicity and injuries is employed in plethora of studies conducted in different animal models and culture systems. This review provides a comprehensive account of the injuries and symptoms that occur upon ocular SM exposures in human patients as well as studies in animal (in vivo, ex vivo) and cell (in vitro) models of SM and NM ocular exposures. Special emphasis has been laid on highlighting the strengths and lacunae in the research as well as the possible unexplored avenues of mechanisms underlying mustard-induced ocular injury that can be explored in future research endeavors. Furthermore, development of therapeutic interventions and targets of interest in the ocular system exposed to SM and NM, based on studies in human patients as well as in vivo, ex vivo, and in vitro models has been discussed in great depth, providing a valuable knowledge database to delineate pathways associated with vesicant-induced toxicity, and strategies/diagnostic tools against SM-induced toxicity.

Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview

Several epidemiologic and toxicological studies have commonly viewed ambient fine particulate matter (PM_2.5), defined as particles having an aerodynamic diameter of less than 2.5 µm, as a significant potential danger to human health. PM_2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. In the respiratory system, reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress stimulate the generation of mediators of pulmonary inflammation and begin or promote numerous illnesses. According to the most recent data, fine particulate matter, or PM_2.5, is responsible for nearly 4 million deaths globally from cardiopulmonary illnesses such as heart disease, respiratory infections, chronic lung disease, cancers, preterm births, and other illnesses. There has been increased worry in recent years about the negative impacts of this worldwide danger. The causal associations between PM_2.5 and human health, the toxic effects and potential mechanisms of PM_2.5, and molecular pathways have been described in this review.

Therapeutic measures for sulfur mustard-induced ocular injury

The use of sulfur mustard (SM) in global terrorism is still a relevant threat to both civilian population and military personnel. Casualties exposed to SM may present mild, moderate or severe acute ocular lesions followed by a complete ocular resolution, chronic lesions or re-emerged ocular pathologies after a latent period. Current treatment for SM-induced ocular injury is based mainly on the clinical manifestation at the different stages of the injury and includes pharmaceutical and surgical interventions. These therapeutic measures are beneficial but not sufficient, and the ocular injury remains a continuous challenge for medical professionals. This review focuses on treatment experience carried out in humans and studied in animal models, for both SM-induced ocular acute injury and late pathology. In general, therapeutic measures are based on clinical features of the ocular injury or on the involvement of specific factors during the ocular injury that point out towards potential treatments. Anti-inflammatory treatments and limbal stem cell transplantation techniques were developed based on the clinical manifestation of the ocular injury. Optional therapies for impaired corneal innervation and endothelium are suggested for future research. Additionally, studies on potential treatments with anti-matrix metalloproteinase (MMP), anti-vascular endothelial growth factor (VEGF) and anti-IL-6 agents are discussed. Consequently, future studies may reveal the potential of additional pharmacological and biological treatments or advanced cellular and molecular biology methods to serve as novel therapeutic measures and techniques for this complicated ocular injury.

Potential of mesenchymal stem cells as topical immunomodulatory cell therapies for ocular surface inflammatory disorders

Ocular surface inflammatory disorders (OSIDs) are a group of highly prevalent, heterogeneous diseases that display a variety of aetiologies and symptoms and are risk factors for serious complications, including ocular and cornea impairment. Corneal inflammation is a common factor of all OSIDs, regardless of their cause or symptoms. Current medications include over-the-counter lubricating eye drops, corticosteroids, and ciclosporin, which either do not treat the corneal inflammation or have been associated with multiple side effects leading to alternative treatments being sought. Regenerative medicine cell therapies, particularly mesenchymal stem cells (MSCs), have shown great promise for immunosuppression and disease amelioration across multiple tissues, including the cornea. However, for successful development and clinical translation of MSC therapy for OSIDs, significant problems must be addressed. This review aims to highlight considerations, including whether the source of MSC isolation impacts the efficacy and safety of the therapy, in addition to assessing the feasibility of MSC topical application to the cornea and ocular surface through analysis of potential scaffolds and cell carriers for application to the eye. The literature contains limited data assessing MSCs incorporated into scaffolds for corneal administration, thus here we highlight the necessity of further investigations to truly exploit the potential of an MSC-based cell therapy for the treatment of OSIDs.

A rabbit model for evaluating ocular damage from acrolein toxicity in vivo

Acrolein is a highly reactive and volatile unsaturated aldehyde commonly used for producing scores of commercial products. It has been recognized as a chemical weapon since its use during World War I, and more recently, in Syria. Acrolein exposure causes severe eye, skin, and lung damage in addition to many casualties. In the eye, it causes severe pain, eyelid swelling, corneal burns, and vision impairment. Very little information is available about how acrolein damages the cornea and causes vision loss. At present, the lack of clinically relevant animal models limits evaluation of acrolein toxicity and mechanisms specific to the eye. We aim to standardize the mode of delivery and exposure duration of acrolein, damaging the rabbit eye in vivo as an ocular injury model for studying the toxicity of acrolein and developing medical countermeasures. Rabbit eyes were exposed to two modes of delivery (topical and vapor) for different durations (1-5 minutes). Clinical ophthalmic examinations with a slit lamp, stereomicroscope, fluorescein dye, pachymeter, tonometer, and tearing examinations in live rabbits were performed at various times up to 4 weeks. Corneas were histologically diagnosed for transparency, fibrosis, collagens, and neovascularization. Our study successfully established an in vivo rabbit model for evaluating acrolein toxicity to the eye, accounting for different modes and durations of exposure.

Toward understanding the purely geometric effects of silver nanoparticles on potential application as ocular therapeutics via treatment of bacterial keratitis

Understanding a complex interaction between therapeutic nanoparticles and biological entities is crucially important for the development of effective disease treatments in the modern nanopharmaceuticals and nanomedicines. Herein, we present a strategy to thoroughly assess geometrical impacts of silver nanoparticles (AgNPs, one of the most promising nanotherapeutic agents) on their biological activities toward treatment of Staphylococcus aureus (S. aureus)-induced keratitis. Specifically, three types of differently shaped AgNPs including silver nanorods (R-Ag), silver nanotriangles (T-Ag), and silver nanospheres (SAg) are employed and interferences of particle surface area and functionality are eliminated to reflect purely geometric effects. Ocular biocompatibility studies on rabbit corneal keratocytes reveal that SAg is the least cytotoxic agent while R-Ag, because of its strongest cellular uptake, induces highest cytotoxic levels. Moreover, SAg is demonstrated to outperform R-Ag and T-Ag in killing S. aureus, possibly due to a predominance of specific particle density and high-atom-density {111} facets of the SAg when interacting with the bacteria. In contrast, owing to its predominance of sharp-tip effects on vascular endothelial cells, R-Ag can suppress blood vessel development in cornea at a greatest extent. In a rabbit model of S. aureus-induced keratitis, intrastromal administration of the differently shaped AgNPs exhibits critical roles of the particle geometry at comparable conditions (i.e., total surface area and functionality) in attenuating progression of S. aureus-induced keratitis. As a compromise among ocular biocompatibility, anti-bacterial activity, and anti-angiogenic capability, SAg shows as the most effective agent that could repair infectious corneal tissues 1.2 and 4-fold greater than the anisotropic counterparts (R-Ag and T-Ag). These findings therefore suggest a promising strategy for a clear-cut evaluation on geometric effects of therapeutic nanoparticles toward preclinical treatment of eye-related microbial infections.

Effect of Cross-Linking Density on the Structures and Properties of Carbodiimide-Treated Gelatin Matrices as Limbal Stem Cell Niches

Given that human amniotic membrane is a valuable biological material not readily available for corneal epithelial tissue engineering, gelatin is considered as a potential alternative to construct a cellular microenvironment. This study investigates, for the first time, the influence of cross-linking density of carbodiimide-treated gelatin matrices on the structures and properties of artificial limbal stem cell niches. Our results showed that an increase in the carbodiimide concentration from 1.5 to 15 mM leads to an upward trend in the structural and suture strength of biopolymers. Furthermore, increasing number of cross-linking bridges capable of linking protein molecules together may reduce their crystallinity. For the samples treated with 50 mM of cross-linker (i.e., the presence of excess N-substituted carbodiimide), abundant N-acylurea was detected, which was detrimental to the in vitro and in vivo ocular biocompatibility of gelatin matrices. Surface roughness and stiffness of biopolymer substrates were found to be positively correlated with carbodiimide-induced cross-link formation. Significant increases of integrin β1 expression, metabolic activity, and ABCG2 expression were noted as the cross-linker concentration increased, suggesting that the bulk crystalline structure and surface roughness/stiffness of niche attributed to the number of cross-linking bridges may have profound effects on a variety of limbal epithelial cell behaviors, including adhesion, proliferation, and stemness maintenance. In summary, taking the advantages of carbodiimide cross-linking-mediated development of gelatin matrices, new niches with tunable cross-linking densities can provide a significant boost to maintain the limbal stem cells during ex vivo expansion.

Expression and significance of the Hedgehog signal transduction pathway in oxygen-induced retinal neovascularization in mice

Aim

The aim of the study was to investigate the signal transduction mechanism of Hedgehog–vascular endothelial growth factor in oxygen-induced retinopathy (OIR) and the effects of cyclopamine on OIR.

Methods

An OIR model was established in C57BL/6J mice exposed to hyperoxia. Two hundred mice were randomly divided into a control group, an OIR group, an OIR-control group (treated with isometric phosphate-buffered saline by intravitreal injection), and a cyclopamine group (treated with cyclopamine by intravitreal injection), with 50 mice in each group. The retinal vascular morphology was observed using adenosine diphosphatase and number counting using hematoxylin and eosin-stained image. Quantitative real-time quantitative polymerase chain reaction was used to detect mRNA expression. Protein location and expression were evaluated using immunohistochemistry and Western blot.

Results

The OIR group and OIR-control group demonstrated large-area pathological neovascularization and nonperfused area when compared with the control group (both P<0.05). The area of nonperfusion and neovascularization in the cyclopamine group was significantly reduced compared with the OIR and OIR-control groups (both P<0.05). Compared with the control group, the OIR and OIR-control groups had more vascular endothelial cells breaking through the inner limiting membrane. The number of new blood vessel endothelial cell nuclei in the cyclopamine group was significantly reduced (both P<0.05) when compared with the OIR and OIR-control groups. The mRNA and protein expressions of Smoothened, Gli1, and vascular endothelial growth factor in the signal pathway of the OIR and OIR-control groups were significantly higher than those of the control group; however, in the cyclopamine group, these factors were reduced when compared with the OIR and OIR-control groups (all P<0.05).

Conclusion

Our data suggest that abnormal expression of the Hedgehog signaling pathway may be closely associated with the formation of OIR. Inhibiting the Smoothened receptor using cyclopamine could control retinal neovascularization, providing new ideas and measures for the prevention of oxygen-induced retinal neovascularization.

Gelatin-Based Photocurable Hydrogels for Corneal Wound Repair

In this study, an injectable, photocurable gelatin system, consisting of acrylated gelatin and thiolated gelatin, with tunable mechanical, biodegradation, and biological properties was used as a potential cell-supportive scaffold for the repair of focal corneal wounds. The mechanical property of hydrogels can be readily modified (postcure shear modulus of between 0.3 and 22 kPa) by varying the ratio of acrylate to thiol groups, photointensity, and solid content, and the biodegradation times also varied with the change of solid content. More importantly, the generated hydrogels exhibited excellent cell viability in both cell seeding and cell encapsulation experiments. Furthermore, the hydrogels were found to be biocompatible with rabbit cornea and aided the regeneration of a new tissue under a focal corneal wound (exhibiting epithelial wound coverage in <3d), and ultraviolet irradiation did not have any obvious harmful effect on the cornea and posterior eye segment tissues. Along with their injectability and tunable mechanical properties, the photocurable thiol-acrylate hydrogels showed promise as corneal substitutes or substrates to construct a new corneal tissue.

The effects for PM2.5 exposure on non-small-cell lung cancer induced motility and proliferation

Background

Increasing urbanization and associated air pollution, including elevated levels of particulate matter (PM), are strongly correlated with the development of various respiratory diseases. In particular, PM2.5 has been implicated in promoting lung cancer initiation, growth and progression. Cell migration and proliferation are crucial for the progression of cancer. However, the molecular signatures and biological networks representing the distinct and shared features of non-small cell lung cancer (NSCLC) after PM2.5 exposure are unknown.

Results

Functional assays demonstrated higher proliferation, migration and invasion of cancer cells stimulated with PM2.5. To investigate the complicated mechanisms, we performed global transcriptome profiling of the A549 cell line. Particularly, transcriptome sequencing revealed invasive characteristics reminiscent of cancer cells. By comparing the transcriptomes, we identified distinct molecular signatures and cellular processes defining the invasive and proliferative properties of PM2.5-exposed cells, respectively. Interestingly, under the PM2.5-stimulated condition, the A549 and H1299 cells strengthened obviously properties in motility and proliferation. Based on the network model reconstructing the shared protein–protein interactions, we selected the two most up-regulated genes, interleukin-1β (IL1β) and matrix metalloprotease 1 (MMP1), as key regulators responsible for the effects of PM2.5 exposure. Notably, IL1β and MMP1 expression was elevated in independent assays, which was further enhanced by PM2.5.

Conclusion

Taken together, our systems approach to investigating PM2.5 exposure provides a basis to identify key regulators responsible for the pathological features of NSCLC.

Hyaluronic acid concentration-mediated changes in structure and function of porous carriers for corneal endothelial cell sheet delivery

In this study, the effects of hyaluronic acid (HA) concentrations (0.05-1.25wt.%) on the properties of porous carriers for corneal endothelial tissue engineering were investigated. The pore size and porosity gradually increased with decreasing solid content. However, at relatively low HA concentration (i.e., 0.05wt.%), the material samples contained small interior pores and a dense surface skin layer, probably due to no gas bubble effect on the stirring processing of porous microstructures of freeze-dried polysaccharide hydrogels. The carriers prepared from 0.25wt.% HA solution had the highest freezable water content and oxygen and glucose permeability among the samples evaluated. Results of cell viability assays and quantitative real-time reverse transcription polymerase chain reaction analyses showed that the HA concentration-related alteration of porous microstructure dictates the compatibility of biopolymer carriers with corneal endothelial cell (CEC) cultures. In vivo studies demonstrated that the CEC sheet/HA carrier construct implants are therapeutically efficacious in the reconstruction of endothelial scrape-wounded corneas. It is concluded that the polysaccharide concentration is the major factor for affecting the processing of carriers and their structure and function. Porous hydrogels prepared from 0.25wt.% HA solution are capable of delivering bioengineered CEC sheets to the posterior surface of cornea.

Effect of riboflavin concentration on the development of photo-cross-linked amniotic membranes for cultivation of limbal epithelial cells

Riboflavin concentration is critical to tailor the cross-linking degree of the collagen network and thus the nanostructure of photo-cross-linked amniotic membrane for cultivation of limbal stem cells.

Critical appraisal of loteprednol ointment, gel, and suspension in the treatment of postoperative inflammation and pain following ocular and corneal transplant surgery

Purpose

To review comprehensively the available peer-reviewed published articles in the literature on loteprednol suspension, gel, and ointment in the treatment of ocular inflammation and pain following ocular surgery.

Methods

We conducted a PubMed literature search review of all published articles on keywords associated with loteprednol etabonate and ocular surgery.

Results

A total of 59 peer-reviewed articles were found in the literature. The focus of the majority of the articles was on the safety and efficacy of loteprednol etabonate 0.5% in postoperative control of inflammation and pain following cataract surgery. There were only three articles with a remote association between loteprednol etabonate and keratoplasty.

Conclusion

Lotemax® ointment may also have potential as a first-line anti-inflammatory agent of choice in postoperative settings of strabismus and penetrating glaucoma, and following low-risk penetrating keratoplasty procedures.

Interrelationship between cross-linking structure, molecular stability, and cytocompatibility of amniotic membranes cross-linked with glutaraldehyde of varying concentrations

Chemical cross-linker concentration has a marked influence on the interrelationship between cross-linking structure, molecular stability, and cytocompatibility of a glutaraldehyde-treated amniotic membrane for a limbal stem cell niche.

Comparison of upstream regulators in human ex vivo cultured cornea limbal epithelial stem cells and differentiated corneal epithelial cells

Background

The surface of the human eye is covered by corneal epithelial cells (CECs) which regenerate from a small population of limbal epithelial stem cells (LESCs). Cell therapy with LESCs is a non-penetrating treatment for preventing blindness due to LESC deficiency or dysfunction. Our aim was to identify new putative molecular markers and upstream regulators in the LESCs and associated molecular pathways.

Results

Genome-wide microarray transcriptional profiling was used to compare LESCs to differentiated human CECs. Ingenuity-based pathway analysis was applied to identify upstream regulators and pathways specific to LESCs. ELISA and flow cytometry were used to measure secreted and surface expressed proteins, respectively. More than 2 fold increase and decrease in expression could be found in 1830 genes between the two cell types. A number of molecules functioning in cellular movement (381), proliferation (567), development (552), death and survival (520), and cell-to-cell signaling (290) were detected having top biological functions in LESCs and several of these were confirmed by flow cytometric surface protein analysis. Custom-selected gene groups related to stemness, differentiation, cell adhesion, cytokines and growth factors as well as angiogenesis could be analyzed. The results show that LESCs play a key role not only in epithelial differentiation and tissue repair, but also in controlling angiogenesis and extracellular matrix integrity. Some pro-inflammatory cytokines were found to be important in stemness-, differentiation- and angiogenesis-related biological functions: IL-6 and IL-8 participated in most of these biological pathways as validated by their secretion from LESC cultures.

Conclusions

The gene and molecular pathways may provide a more specific understanding of the signaling molecules associated with LESCs, therefore, help better identify and use these cells in the treatment of ocular surface diseases.

Glutaraldehyde cross-linking of amniotic membranes affects their nanofibrous structures and limbal epithelial cell culture characteristics

Given that the cells can sense nanometer dimensions, the chemical cross-linking-mediated alteration in fibrillar structure of collagenous tissue scaffolds is critical to determining their cell culture performances. This article explores, for the first time, the effect of nanofibrous structure of glutaraldehyde (GTA) cross-linked amniotic membrane (AM) on limbal epithelial cell (LEC) cultivation. Results of ninhydrin assays demonstrated that the amount of new cross-links formed between the collagen chains is significantly increased with increasing the cross-linking time from 1 to 24 hours. By transmission electron microscopy, the AM treated with GTA for a longer duration exhibited a greater extent of molecular aggregation, thereby leading to a considerable increase in nanofiber diameter and resistance against collagenase degradation. In vitro biocompatibility studies showed that the samples cross-linked with GTA for 24 hours are not well-tolerated by the human corneal epithelial cell cultures. When the treatment duration is less than 6 hours, the biological tissues cross-linked with GTA for a longer time may cause slight reductions in 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt, and anti-inflammatory activities. Nevertheless, significant collagen molecular aggregation also enhances the stemness gene expression, indicating a high ability of these AM matrices to preserve the progenitors of LECs in vitro. It is concluded that GTA cross-linking of collagenous tissue materials may affect their nanofibrous structures and corneal epithelial stem cell culture characteristics. The AM treated with GTA for 6 hours holds promise for use as a niche for the expansion and transplantation of limbal epithelial progenitor cells.

Novel anti(lymph)angiogenic treatment strategies for corneal and ocular surface diseases

The cornea is one of the few tissues which actively maintain an avascular state, i.e. the absence of blood and lymphatic vessels (corneal [lymph]angiogenic privilege). Nonetheless do several diseases interfere with this privilege and cause pathologic corneal hem- and lymphangiogenesis. The ingrowths of pathologic blood and lymphatic vessels into the cornea not only reduce transparency and thereby visual acuity up to blindness, but also significantly increases the rate of graft rejections after subsequent corneal transplantation. Therefore great interest exists in new strategies to target pathologic corneal (lymph)angiogenesis to promote graft survival. This review gives an overview on the vascular anatomy of the normal ocular surface, on the molecular mechanisms contributing to the corneal (lymph)angiogenic privilege and on the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea. In addition we summarize the current preclinical and clinical evidence for three novel treatment strategies against ocular surface diseases based on targeting pathologic (lymph)angiogenesis: (a) modulation of the immune responses after (corneal) transplantation by targeting pathologic (lymph)angiogenesis prior to and after transplantation, (b) novel concepts against metastasis and recurrence of ocular surface tumors such as malignant melanoma of the conjunctiva by anti(lymph)angiogenic therapy and (c) new ideas on how to target ocular surface inflammatory diseases such as dry eye by targeting conjunctival and corneal lymphatic vessels. Based on compelling preclinical evidence and early data from clinical trials the novel therapeutic concepts of promoting graft survival, inhibiting tumor metastasis and dampening ocular surface inflammation and dry eye disease by targeting (lymph)angiogenesis are on their way to translation into the clinic.