Hyaluronic acid-dependent protection against alkali-burned human corneal cells

Enhanced Corneal Repair with Hyaluronic Acid/Proanthocyanidins Nanoparticles

This study investigates the therapeutic potential of hyaluronic acid/proanthocyanidin (HA/PAC) nanoparticles in treating alkali-induced corneal burns. Alkali burns are common ocular emergencies that can lead to severe vision impairment if not promptly and properly treated. The low water solubility of proanthocyanidins (PACs), which are potent antioxidant and anti-inflammatory agents, limits their bioavailability and therapeutic efficacy. To overcome this, hyaluronic acid (HA) was utilized as a carrier to form HA/PAC nanoparticles, enhancing PAC's solubility and bioavailability. The HA/PAC nanoparticles were characterized for morphology, granulometric distribution, hemolysis, and cytotoxicity, demonstrating high blood compatibility and noncytotoxicity. The in vitro antioxidant and anti-inflammatory capacities of HA/PAC were evaluated, showing enhanced activity compared to PAC alone. In vivo studies on C57 mice confirmed the accelerated healing of corneal injuries and reduced corneal opacity with HA/PAC treatment. Histopathological analysis and cytokine quantification further supported the anti-inflammatory and proregenerative effects of HA/PAC, suggesting its potential as an effective treatment for corneal alkali burns.

Overview of 37 Tear Substitutes in Europe Based on Various Physicochemical Parameters

INTRODUCTION

Dry eye disease (DED) is one of the most prevalent eye conditions worldwide, with artificial tears serving as a primary treatment option. Despite their wide availability on the European market, there is a lack of established classifications based on their physicochemical properties. The aim of our study was therefore (i) to develop an analytical method that measures the concentration and the molecular weight (MW) of the hyaluronic acid (HA) in commercialized products, and (ii) to propose an overview based on their various physicochemical parameters.

METHODS

The intrinsic viscosity and MW of the HA, as well as osmolarity, pH, rheological profile, and viscosity, were measured or determined. A specific method was developed to measure the average intrinsic viscosity and HA content using a liquid size-exclusion chromatography system. The MW was determined using the Mark-Houwink equation.

RESULTS

Thirty-seven products commercialized in Europe were analyzed, with 21 of them containing HA. The HA MW was lowest (300 kDa) for Thealose®, Thealoz Duo® Gel, and Hyabak®, and highest (1300 kDa) for Vismed® Multi, Vismed® Gel, and Neovis® Gel. The pH values varied between 5.94 for Treovis® and 8.06 for Systane® Ultra. Osmolarity ranged between 148 mOsm/L and 325 mOsm/L for Neovis® and Treovis®, respectively. Viscosity was highly variable, ranging from 0.38 mPas·s for Hylolipid® to 337.47 mPas·s for Thealoz® Duo Gel. Finally, rheological profile analysis revealed different shear-thinning behaviors.

CONCLUSION

While the perfect eye drop does not exist, a multitude of options are available to choose from. This study improves our understanding of the major tear substitutes available on the European market based on several physicochemical properties. A better understanding and awareness of these parameters is crucial in order to offer the best treatment for patients with DED.

Wnt activation as a potential therapeutic approach to treat partial limbal stem cell deficiency

Limbal epithelial stem/progenitor cells (LSCs) are adult stem cells located at the limbus, tightly regulated by their niche involving numerous signaling pathways, such as Wnt. Wnt proteins are secreted morphogens that play critical roles in embryonic development, stem cell proliferation, self-renewal, tissue regeneration, and remodeling in adults. It has been shown that a small molecule Wnt mimic could improve LSCs expansion ex vivo. Damage to the LSCs and/or their niche can lead to limbal stem cell deficiency (LSCD), a condition that can cause corneal blindness and is difficult to treat. This study explored if repopulating residual LSCs in partial LSCD through Wnt activation could be a novel therapeutic approach. To mimic LSCD due to a chemical injury, single cultured LSCs were exposed to various concentrations of sodium hydroxide. A progressive loss of the LSCs phenotype was observed: the percentage of p63bright cells and cytokeratin (K)14+ cells decreased while the percentage of K12+ increased. Wnt activation was attained by treating the LSCs with lithium chloride (LiCl) and a small-molecule Wnt mimic, respectively. After 18 h of treatment, LSCs proliferation was increased, and the LSCs phenotype was recovered, while the untreated cells did not proliferate and lost their phenotype. The percentage of p63bright cells was significantly higher in the Wnt mimic-treated cells compared with untreated cells, while the percentage of K12+ cells was significantly lower. These findings suggest that local Wnt activation may rescue LSCs upon alkaline injury.

A randomized controlled trial involving college student: Comparing 0.15% hyaluronic acid with 0.05% cyclosporine A and 3% diquafosol sodium in the Treatment of Dry Eye

BACKGROUND

To compare the efficacy of 0.15% hyaluronic acid (HA), 0.05% cyclosporine A (CsA) and 3% diquafosol sodium (DQS) ophthalmic solution for the treatment of moderate-to-severe dry eye disease (DED) in college students and the effect on inflammatory factors in tears.

METHODS

This was a prospective, randomized, multicenter trial. A total of 282 college students diagnosed with moderate-to-severe DED between October 2, 2022 and March 1, 2023 were included. A total of 282 patients were randomized to treatment in the group of 0.15% HA or 0.05% CsA or 3% DQS in a 1:1:1 assignment. There was a main end point which is the variations in the corneal staining score to determine non-inferiority of 0.15% HA. Secondary target end points were ocular surface disease index score, Schirmer test, tear meniscus height and tear film breakup time. In addition, the inflammatory factor levels of Interleukin-1β, Interleukin-6, transforming growth factor-β1 in tears were measured. Effectiveness was assessed at baseline, 4- and 12-weeks.

RESULTS

In our analysis, the average change from baseline in corneal staining score confirmed non-inferiority of 0.15% HA to 0.05% CsA and 3% DQS and manifested obvious improvement of all groups as well (P < .05). Values for ocular surface disease index score, Schirmer test, tear meniscus height and tear film breakup time showed obvious improvements in all groups (P < .05), however, the difference intergroup was not statistically significant. Value for inflammatory factor was significant improvement across all groups, although inflammatory factor scores in the 0.05% CsA group showed a clear trend of better improvement at 12 weeks compared with 0.15% HA groups (P < .01). No serious adverse reactions were observed.

CONCLUSIONS

College students taking 0.15% HA had clinically and statistically significant improvement in corneal staining score and other indicators, but it was inferior to 0.05% CsA in anti-inflammatory therapy for moderate to severe DED. However, 0.15% HA is still an effective, safe and well-tolerated treatment option that may offer additional benefits in terms of convenience and compliance.

Corneal wound healing and nerve regeneration by novel ophthalmic formulations based on cross-linked sodium hyaluronate, taurine, vitamin B6, and vitamin B12

Introduction: To evaluate the pharmacological profile of ocular formulations based on cross-linked sodium hyaluronate (CL-SH), taurine (Tau), vitamin B6 (Vit B6) and vitamin B12 (Vit B12) using in vitro and in vivo paradigms. Methods: Rabbit corneal epithelial cells were used to assess wound healing and reactive oxygen species (ROS) formation by scratch assay and oxidative stress (0.3 mM H₂O₂; 30 min), respectively with or without ocular formulations exposure. In vivo studies were carried out on albino rabbits to evaluate corneal nerve regeneration and corneal wound healing with or without treatment with six different formulations. Animals were anesthetized, the corneal epithelium was removed, and formulations were topically administered (30 μL/eye; 3 times/day for 6 days). Slit-lamp observation was carried out at different time points. After 6 days the animals were killed, and corneas were collected to evaluate corneal re-innervation by immunohistochemistry of selective neuronal marker β-III tubulin. Results: Formulations containing the concentrations 0.16% or 0.32% of cross-linked sodium hyaluronate, taurine, vitamin B6 and vitamin B12 accelerated corneal wound healing. Cells exposed to H₂O₂ led to significant (p < 0.05) increase of reactive oxygen species concentration that was significantly (p < 0.05) counteract by formulations containing cross-linked sodium hyaluronate (0.32%) and taurine with or without vitamins. The extent of re-innervation, in terms of β-III tubulin staining, was 5-fold greater (p < 0.01) in the eye of rabbits treated with formulation containing 0.32% cross-linked sodium hyaluronate, taurine, vitamins (RenerviX^®) compared with the control group (no treatment). Furthermore, re-innervation elicited by RenerviX^® was significantly greater (p < 0.01) compared with the group treated with the formulation containing 0.32% cross-linked sodium hyaluronate and taurine without vitamins, and with the group treated with the formulation containing 0.5% linear sodium hyaluronate (SH), taurine, and vitamin B12, respectively. Discussion: In conclusion, among the formulations tested, the new ophthalmic gel RenerviX^® was able to contrast oxidative stress, to accelerate corneal re-epithelization and to promote nerve regeneration.

Artificial Tears: A Systematic Review

Artificial tears are the mainstay of dry eye disease management, but also have a role in corneal abrasion and wound healing, pain and inflammation management, conjunctivitis, keratitis, contact lens rewetting and removal, and foreign body removal. A systematic review of randomized controlled trials (PROSPERO registration CRD42022369619) comparing the efficacy of artificial tears in patients with dry eye to inform prescribing choices using Web of Science, PubMed and Medline databases identified 64 relevant articles. There is good evidence that artificial tears improve symptoms of dry eye disease within a month of regular use, applied about four times a day, but signs generally take several months to improve. Not all patients with dry eye disease benefit from artificial tears, so if there is no benefit over a month, alternative management should be considered. Combination formulations are more effective than single active ingredient artificial tears. Artificial tears containing polyethylene glycol are more effective than those containing carboxymethylcellulose/carmellose sodium and hydroxypropyl methylcellulose. Those classified as having evaporative dry eye disease, benefit from artificial tears with liposomes, especially of higher concentration. The data available is limited by the definition of dry eye disease applied in published studies being variable, as well as the disease severity examined and compliance with artificial tears being rarely quantified.

Hyaluronic acid in the treatment of dry eye disease

Dry eye disease (DED) is a highly prevalent and debilitating condition affecting several hundred million people worldwide. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan commonly used in the treatment of DED. This review aims to critically evaluate the literature on the safety and efficacy of artificial tears containing HA used in DED treatment. Literature searches were conducted in PubMed, including MEDLINE, and in Embase via Ovid with the search term: "(hyaluronic acid OR hyaluronan OR hyaluronate) AND (dry eye OR sicca)". A total of 53 clinical trials are included in this review, including eight placebo-controlled trials. Hyaluronic acid concentrations ranged from 0.1% to 0.4%. Studies lasted up to 3 months. A broad spectrum of DED types and severities was represented in the reviewed literature. No major complications or adverse events were reported. Artificial tears containing 0.1% to 0.4% HA were effective at improving both signs and symptoms of DED. Two major gaps in the literature have been identified: 1. no study investigated the ideal drop frequency for HA-containing eyedrops, and 2. insufficient evidence was presented to recommend any specific HA formulation over another. Future investigations assessing the optimal drop frequency for different concentrations and molecular weights of HA, different drop formulations, including tonicity, and accounting for DED severity and aetiology are essential for an evidence-based, individualized approach to DED treatment.

Hyaluronic acid hydrogels crosslinked via blue light-induced thiol-ene reaction for the treatment of rat corneal alkali burn

To assess corneal inflammation from alkali chemical burns, we examined the therapeutic effects of in situ-forming hyaluronic acid (HA) hydrogels crosslinked via blue light-induced thiol-ene reaction on a rat corneal alkali burn model. Animals were divided into three groups (n = 7 rats per group): untreated, treated with 0.1% HA eye drops, and treated with crosslinked HA hydrogels. Crosslinking of HA hydrogel followed by the administration of HA eye drops and crosslinked HA hydrogels were carried out once a day from days 0–4. Corneal re-epithelialization, opacity, neovascularization, thickness, and histology were evaluated to compare the therapeutic effects of the three groups. Further investigation was conducted on the transparency of HA hydrogels to acquire the practical capabilities of hydrogel as a reservoir for drug delivery. Compared to untreated animals, animals treated with crosslinked HA hydrogels exhibited greater corneal re-epithelialization on days 1, 2, 4, and 7 post-injury (p = 0.004, p = 0.007, p = 0.008, and p = 0.034, respectively) and the least corneal neovascularization (p = 0.008). Histological analysis revealed lower infiltration of stromal inflammatory cells and compact collagen structure in crosslinked HA hydrogel-treated animals than in untreated animals. These findings corresponded with immunohistochemical analyses indicating that the expression of inflammatory markers such as α-SMA, MMP9, and IL1-β was lower in animals treated with crosslinked HA hydrogels than untreated animals and animals treated only with 0.1% HA eye drops. With beneficial pharmacological effects such as re-epithelization and anti-inflammation, in situ-forming hyaluronic acid (HA) hydrogels may be a promising approach to effective drug delivery in cases of corneal burn injuries.

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Corneal chemical injuries can induce corneal opacification, limbal ischemia, and loss of vision.

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Limitations for using topical eye drops includes maintaining the optimal concentration of the drug on the ocular surface.

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Crosslinked HA hydrogels achieved rapid corneal re-epithelialization and low-grade neovascularization after chemical injury.

Drp1-dependent mitochondrial fission mediates corneal injury induced by alkali burn

Corneal alkali burn, one of the most serious ophthalmic emergencies, is difficult to be cured by conservative treatments. It is well known that oxidative stress, inflammation and neovascularization are the main causes of corneal damage after alkali burn, but its underlying mechanism remains to be elucidated. Here, we reported that the expression and phosphorylation (Ser616) of mitochondrial fission protein Drp1 were up-regulated at day 3 after alkali burn, while mitochondrial fusion protein Mfn2 was down-regulated. The phosphorylation of ERK1/2 in corneas was increased at day 1, 3, 7 and peaked at day 3 after alkali burn. In human corneal epithelial cells (HCE-2), NaOH treatment induced mitochondrial fission, intracellular ROS production and mitochondrial membrane potential disruption, which was prevented by Drp1 inhibitor Mdivi-1. In corneas, Mdivi-1 or knockdown of Drp1 by Lenti-Drp1 shRNA attenuated alkali burn-induced ROS production and phosphorylation of IκBα and p65. In immunofluorescence staining, it was detected that Mdivi-1 also prevented NaOH-induced nuclear translocation of p65 in HCE-2 cells. Moreover, the expression of NADPH oxidase NOX2 and NOX4 in corneas peaked at day 7 after alkali burn. Mdivi-1, Lenti-Drp1 shRNA or the mitochondria-targeted antioxidant mito-TEMPO efficiently alleviated activation of NF-κB, expression of NOX2/4 and inflammatory cytokines including IL-6, IL-1β and TNF-α in corneas after alkali burn. In pharmacological experiments, both Mdivi-1 and NADPH oxidases inhibitor Apocynin protected the corneas against alkali burn-induced neovascularization. Intriguingly, the combined administration of Mdivi-1 and Apocynin had a synergistic inhibitory effect on corneal neovascularization after alkali burn. Taken together, these results indicate that Drp1-dependent mitochondrial fission is involved in alkali burn-induced corneal injury through regulating oxidative stress, inflammatory responses and corneal neovascularization. This might provide a novel therapeutic target for corneal injury after alkali burn in the future.

Development of a novel hyaluronic acid membrane for the treatment of ocular surface diseases

Ocular surface diseases (OSD) can cause serious visual deterioration and discomfort. Commercial artificial tear solution containing hyaluronic acid (HA) show excellent biocompatibility and unique viscoelastic characteristics. Here, we developed a novel HA membrane (HAM) by chemical crosslinking using 1,4-butanediol diglycidyl ether for the effective treatment of OSDs. The main purpose of HAMs is to provide sustained release of HA to modulate the wound healing response in OSDs. The safety and efficacy of HAMs were investigated using primary cultured human corneal epithelial cells and various OSD rabbit models. In the dry state, the HAM is firm, transparent, and easy to manipulate. When hydrated, it swells rapidly with high water retention and over 90% transmission of visible light. Human corneal epithelial cells and rabbit eyes showed no toxic response to HAM. Addition of HAMs to the culture medium enhanced human corneal epithelial cell viability and expression of cell proliferation markers. Investigation of HAM wound healing efficacy using mechanical or chemical corneal trauma and conjunctival surgery in rabbits revealed that application of HAMs to the ocular surface enhanced healing of corneal epithelium and reduced corneal limbal vascularization, opacity and conjunctival fibrosis. The therapeutic potential of HAMs in various OSDs was successfully demonstrated.

Crosslinked Hyaluronic Acid Gels with Blood-Derived Protein Components for Soft Tissue Regeneration

Hyaluronic acid (HA) is an ideal initial material for preparing hydrogels, which may be used as scaffolds in soft tissue engineering based on their advantageous physical and biological properties. In this study, two crosslinking agents, divinyl sulfone (DVS) and butanediol diglycidyl ether, were used to investigate their effect on the properties of HA hydrogels. As HA hydrogels alone do not promote cell adhesion on the scaffold, fibrin and serum from platelet-rich fibrin (SPRF) were combined with the scaffold; the aim was to create a material intended to be used as soft tissue implant that facilitates new tissue formation, and degrades over time. The chemical changes were characterized and cell attachment capacity of the protein-containing gels was examined using human mesenchymal stem cells, and viability was assessed using live-dead staining. Fourier-transform infrared measurements revealed that linking fibrin into the gel was more effective than linking SPRF. The scaffolds were found to be able to support cell adherence onto the hydrogels, and the best result was achieved when HA was crosslinked with DVS and contained fibrin. The most promising derivative, 5% DVS-crosslinked fibrin-containing hydrogel, was injected subcutaneously into C57BL/6 mice for 12 weeks. The scaffold was proven to be biocompatible, remodeling, and vascularization occurred, while shape and integrity were maintained. Impact statement Fibrin was combined with crosslinked hyaluronic acid (HA) for regenerative application, the structure of the combination of crosslinked HA with blood-derived protein was analyzed and effective coating was proven. It was observed that the fibrin content led to better mesenchymal stem cell attachment in vitro. The compositions showed biocompatibility, connective tissue and vascularization took place when implanted in vivo. Thus, a biocompatible, injectable gel was produced, which is a potential candidate for soft tissue implantation.

Topical hyaluronan alone promotes corneal epithelial cell migration whereas combination with benzalkonium chloride impairs epithelial wound healing

Purpose: To evaluate the effects of topical hyaluronan (HA) on corneal epithelial wound healing when administered with or without benzalkonium chloride (BAC).Methods: A cultured human corneal epithelial cell line (HCE-T) was subjected to in vitro scratch assays and in situ epithelial migration was evaluated in organ-cultured rabbit corneas. The corneal epithelium of C57BL/6J mice was also evaluated to determine in vivo wound healing. An in vivo imaging system was also used to evaluate the effects of HA on eye drop retention on the ocular surface.Results: The findings revealed the promotion of HCE-T migration, in situ rabbit corneal epithelial migration, and in vivo wound healing in mouse corneal epithelium by HA. Pre-treatment with HA also protected against delayed epithelial wound healing in BAC in vitro. However, pre-treatment with 3 mg/mL HA did not show a protective effect against BAC in vivo, but instead delayed epithelial wound healing and increased detection of cleaved caspase-3. This suggested that HA promotes the retention of BAC on the ocular surface. The instilled HA was retained after 15 min, at a significantly higher rate than for phosphate-buffered saline.Conclusions: The combination of HA and BAC impaired wound healing in the corneal epithelium.

Combination of urea-crosslinked hyaluronic acid and sodium ascorbyl phosphate for the treatment of inflammatory lung diseases: An in vitro study

This in vitro study evaluated, for the first time, the safety and the biological activity of a novel urea-crosslinked hyaluronic acid component and sodium ascorbyl phosphate (HA-CL - SAP), singularly and/or in combination, intended for the treatment of inflammatory lung diseases. The aim was to understand if the combination HA-CL - SAP had an enhanced activity with respect to the combination native hyaluronic acid (HA) - SAP and the single SAP, HA and HA-CL components. Sample solutions displayed pH, osmolality and viscosity values suitable for lung delivery and showed to be not toxic on epithelial Calu-3 cells at the concentrations used in this study. The HA-CL - SAP displayed the most significant reduction in interleukin-6 (IL-6) and reactive oxygen species (ROS) levels, due to the combined action of HA-CL and SAP. Moreover, this combination showed improved cellular healing (wound closure) with respect to HA - SAP, SAP and HA, although at a lower rate than HA-CL alone. These preliminary results showed that the combination HA-CL - SAP could be suitable to reduce inflammation and oxidative stress in lung disorders like acute respiratory distress syndrome, asthma, emphysema and chronic obstructive pulmonary disease, where inflammation is prominent.

Efficacy of Sodium Hyaluronate in Murine Diabetic Ocular Surface Diseases

Supplemental Digital Content is Available in the Text.

Purpose:

To evaluate the efficacy of sodium hyaluronate (HA) eye drops for the treatment of diabetic ocular surface diseases in mice.

Methods:

Male 6- to 8-week-old C57BL/6 mice underwent induction of type 1 diabetes with intraperitoneal injections of streptozotocin, with normal mice as the control. Topical 0.3% HA, 0.1% HA, 0.4% polyethylene glycol eye drops, and normal saline were administered to diabetic mice with an intact or debrided corneal epithelium. Normal saline was applied in the controls. Corneal epithelial wound healing rate, corneal sensation, nerve fiber density, conjunctival goblet cell number, and MUC-5AC content were measured and compared.

Results:

Compared with the controls, topical 0.3% HA use in diabetic mice showed significant improvements in the corneal epithelial wound healing rate (48 hours: 91.5% ± 4.8% vs. 79.8% ± 6.1%; P < 0.05), corneal sensitivity (4.1 ± 0.3 cm vs. 3.5 ± 0.3 cm; P < 0.05), nerve fiber density (12.9% ± 2.3% vs. 6.6% ± 2.4%; P < 0.05), conjunctival goblet cell number (31.0 ± 8.4/100 μm vs. 19.6 ± 7.1/100 μm; P < 0.05), and MUC-5AC content (12.5 ± 1.4 ng/mg vs. 7.8 ± 1.5 ng/mg protein; P < 0.05). The beneficial effects of 0.3% HA were better than those of 0.1% HA and 0.4% polyethylene glycol.

Conclusions:

Topical 0.3% HA treatment promoted corneal epithelial regeneration, improved corneal sensation, and increased density of corneal nerve fibers and conjunctival goblet cells in mice with diabetic ocular surface diseases.

Combination of hyaluronic acid, carmellose, and osmoprotectants for the treatment of dry eye disease

Background

Dry Eye Disease (DED) is a multifactorial disease, with a high prevalence, that can have a great impact on the quality of life of patients. The first step of treatment includes the use of lacrimal substitutes composed of polymers, possible to associate osmoprotectant agents to the lacrimal substitutes. The aim of this article is to analyze the properties of the combination of hyaluronic acid (HA), carmellose, and osmoprotectors (Optava Fusion^®; Allergan, Inc., Irvine, CA, USA) on DED. General considerations on the use of artificial tears are also proposed.

Methods

A group of ophthalmologists, experts in the management of the ocular surface, analyzed different aspects related to DED; among them, the use of artificial tears in general and the properties of the combination of HA, carmellose, and osmoprotectors, in particular, were discussed. A review of the literature was carried out, which included different articles published in Spanish, English, and French until April 2017.

Conclusions

DED is a common chronic pathology that usually requires sustained treatment. In addition, the combination of HA, carmellose, and osmoprotectors has proven to be effective in the treatment of symptoms and signs of dry eye by the synergistic action of all its components. This review provides key elements to help ophthalmologists who begin in the management of DED.

Treatment of acute ocular chemical burns

Ocular chemical burns are an ophthalmic emergency and are responsible for 11.5%-22.1% of ocular injuries. Immediate copious irrigation is universally recommended in acute ocular burns to remove the offending agent and minimize damage. Conventional medical therapy consists of the use of agents that promote epithelialization, minimize inflammation, and prevent cicatricial complications. Biological fluids such as autologous serum, umbilical cord blood serum, platelet-rich plasma, and amniotic membrane suspension are a rich source of growth factors and promote healing when used as adjuncts to conventional therapy. Surgical treatment of acute ocular burns includes the debridement of the necrotic tissue, application of tissue adhesives, tenoplasty, and tectonic keratoplasty. Amniotic membrane transplantation is a novel surgical treatment that is increasingly being used as an adjunct to conventional treatment to promote epithelial healing, minimize pain, and restore visual acuity. Various experimental treatments that aim to promote wound healing and minimize inflammation are being evaluated such as human mesenchymal and adipose stem cells, beta-1,3 glucan, angiotensin-converting enzyme inhibitors, cultivated fibroblasts, zinc desferrioxamine, antifibrinolytic agents, antioxidants, collagen cross-linking, and inhibitors of corneal neovascularization.

Quantitative proteomic analysis of mice corneal tissues reveals angiogenesis-related proteins involved in corneal neovascularization

Corneal neovascularization (CNV) was induced in Balb/c mice by alkali burns in the central area of the cornea with a diameter of 2.5mm. After fourteen days, the cornea from one eye was collected for histological staining for CNV examination, while the cornea from the other eye of the same mouse was harvested for proteomic analysis. The label-free quantitative proteomic approach was applied to analyze five normal corneal tissues (normal group mice n=5) and five corresponding neovascularized corneal tissues (model group mice n=5). A total of 2124 proteins were identified, and 1682 proteins were quantified from these corneal tissues. Among these quantified proteins, 290 proteins were significantly changed between normal and alkali burned corneal tissues. Of these significantly changed proteins, 35 were reported or predicted as angiogenesis-related proteins. Then, these 35 proteins were analyzed using Ingenuity Pathway Analysis Software, resulting in 26 proteins enriched and connected to each other in the protein-protein interaction network, such as Lcn-2, αB-crystallin and Serpinf1 (PEDF). These three significantly changed proteins were selected for further Western blotting validation. Consistent with the quantitative proteomic results, Western blotting showed that Lcn-2 and αB-crystallin were significantly up-regulated in CNV model, while PEDF was down-regulated. This study provided increased understanding of angiogenesis-related proteins involved in corneal vascular development, which will be useful in the ophthalmic clinic of specifically target angiogenesis.

Effect of hyaluronic acid on tear film thickness as assessed with ultra-high resolution optical coherence tomography

PURPOSE

The aim of this study was to assess the effect of a single drop of hyaluronic acid on tear film thickness (TFT) in healthy subjects.

METHODS

Sixteen healthy subjects (eight male/eight female) aged between 20 and 36 years were included in this randomized, double-masked placebo-controlled study. One eye received a single dose of hyaluronic acid (Olixia pure(®) ; Croma Pharma, Korneuburg, Austria) eye drops, and the fellow eye received physiologic saline solution as placebo control. The study eye was chosen randomly. TFT as measured with a custom-built Fourier-domain optical coherence tomography (FD-OCT) system was the main outcome variable and measured before and every 10 min until 1 hr after topical administration.

RESULTS

Baseline TFT was 4.8 ± 0.5 μm in the study eye and 5.0 ± 0.4 μm in the control eyes. Hyaluronic acid significantly increased TFT (p = 0.008 versus placebo) with a maximum effect 10 min after instillation (13.9 ± 11.9%). Post hoc analysis revealed that an increase in TFT was seen until 30 min after administration compared to placebo. Data in the placebo group show high reproducibility with an intraclass correlation coefficient of 0.93 and a coefficient of variation of 5.4 ± 3.3%.

CONCLUSION

The data of this study indicate that hyaluronic acid increases TFT for as long as 30 min in healthy subjects. In addition, our data provide evidence that our custom-built OCT system is capable of measuring residence time of lubricants on the ocular surface.

Effects of vitamin B12 on the corneal nerve regeneration in rats

The study was designed to investigate the effects of a new ophthalmic solution containing 0.05% vitamin B12 0.05% on corneal nerve regeneration in rats after corneal injury. Eyes of anesthetized male Wistar rats were subjected to corneal injury by removing the corneal epithelium with corneal brush (Algerbrush). After the epithelial debridement, the right eye of each animal received the instillation of one drop of the ophthalmic solution containing vitamin B12 0.05% plus taurine 0.5% and sodium hyaluronate 0.5% four time per day for 10 or 30 days. Left eyes were used as control and treated with solution containing taurine 0.5% and sodium hyaluronate 0.5% alone following the same regimen. Fluorescein staining by slit-lamp and morphological analysis was used to determine corneal wound healing. Immunohistochemistry, immunoblot and confocal microscopy were used to examine corneal re-innervation. Slit-lamp and histological analyses showed that re-epithelization of the corneas was accelerated in rats treated with vitamin B12. A clear-cut difference between the two groups of rats was seen after 10 days of treatment, whereas a near-to-complete re-epithelization was observed in both groups at 30 days. Vitamin B12 treatment had also a remarkable effect on corneal re-innervation, as shown by substantial increased in the expression of neurofilament 160 and β-III tubulin at both 10 and 30 days. The presence of SV2A-positive nerve endings suggests the presence of synapse-like specialized structures in corneal epithelium of the eye treated with vitamin B12. Our findings suggest that vitamin B12 treatment represents a powerful strategy to accelerate not only re-epithelization but also corneal re-innervation after mechanical injury.