The role of high molecular weight hyaluronic acid in mucoadhesion on an ocular surface model

Management of Oxidative Stress and Inflammation in Patients with Symptomatic Dry Eye Disease Treated with a Preservative-Free Ophthalmic Emulsion Combining Alpha-Lipoic Acid and High Molecular Weight Sodium Hyaluronate

INTRODUCTION

This study aimed to explore the beneficial effect of a preservative-free (PF) emulsion eyedrop combining high molecular weight sodium hyaluronate (HMW-HA) and alpha-lipoic acid on oxidative stress and ocular surface inflammation in patients with dry eye disease (DED).

METHODS

In this prospective exploratory study, patients with moderate to severe DED symptoms were treated with the study eyedrop, 4-6 times/day for 1 month. Two visits were scheduled: baseline (D0) and after 35 days (D35). The following parameters were assessed: quality of life (OSDI score); superoxide dismutase (SODase) concentration in tears; goblet cell (GC) density (impression cytology); conjunctival hyperemia (Efron scale); corneal, conjunctival, and eyelid staining (Oxford scale); and meibomian gland (MG) blockage. Data were compared between D0 and D35 in subgroups of patients with a significant abnormality of the study outcome at baseline.

RESULTS

Forty patients were involved, with a highly significant improvement of OSDI score at D35. The mean concentration of SODase significantly increased by 3.2 and 2.4 times for SODase1 and SODase2 respectively, in patients with deficient SODase at baseline. In patients with abnormal GC density at baseline, GC count increased by five times at D35. Conjunctival hyperemia and corneal staining scores significantly improved in the subpopulation of patients with a baseline grade ≥ 2. Eyelid margin staining was significantly reduced at D35 in patients with significant abnormalities at baseline. A significant reduction of MG obstruction was shown in the lower eyelid in patients with significant blockage at baseline.

CONCLUSION

The use of a PF ophthalmic emulsion combining alpha-lipoic acid and HMW-HA shows a beneficial effect on the ocular surface through the improved quality of life score. Noteworthy, patients presenting high oxidative and inflammatory conditions experienced significant improvement in oxidative stress and inflammation markers; this synergic effect is likely due to the well-known properties of alpha-lipoic acid and HMW-HA, enhancing DED management.

TRIAL REGISTRATION

ISRCTN.com identifier, 17861788.

Corneal Mucin-Targeting Liposome Nanoplatforms Enable Effective Treatment of Dry Eye Diseases by Integrated Regulation of Ferroptosis and Inflammation

The incidence of dry eye disease (DED) has been increasing annually worldwide, creating an urgent need for new therapies. Due to the multifactorial mechanism underlying DED, traditional medications focused on decreasing ocular surface inflammation have been unable to address all the harmful factors and fail to achieve a complete clinical cure. Ferroptosis, a new form of programmed cell death characterized by lipid peroxidation, has become a pivotal contributor to dry eye oxidative stress-driven pathology. Therefore, therapeutic targeting of ferroptosis may be an attractive option for dry eye management. Herein, a sialic acid-targeting peptide-modified liposome loaded with Cyclosporine A (CsA), a typical anti-inflammatory drug, and Ferrostatin-1 (Fer-1), a selective ferroptosis inhibitor, is developed termed as CF@SNPs, for combing and sustaining DED treatment. This multifunctional liposomal encapsulation demonstrates excellent aqueous solubility; moreover, the sialic acid-targeting peptide prolongs ocular surface retention, further enhancing therapeutic efficacy. The CF@SNPs treatment comprehensively alleviates DED symptoms, including improving corneal defects, augmenting goblet cell count, and restoring tear secretion. Specifically, CF@SNPs attenuate dry eye pathology by suppressing p53-SLC7A11-GSH-dependent ferroptosis and TNF-α-associated inflammatory cascades, accompanied by favorable biocompatibility in vivo. These results underscore the promising potential of this superior nano-formulation for DED pharmacotherapy.

From Preformulative Design to In Vivo Tests: A Complex Path of Requisites and Studies for Nanoparticle Ocular Application. Part 1: Design, Characterization, and Preliminary In Vitro Studies

Ocular pathologies are widely diffused worldwide, and their effective treatment, combined with a high patient compliance, is sometimes challenging to achieve due to the barriers of the eye; in this context, the use of nanoparticles for topical ophthalmic application could represent a successful strategy. Aiming to develop nanoplatforms with potential clinical applications, great attention has to be paid to their features, in relation to the route of administration and to the pharmacopoeial requirements. This review (part 1) thus embraces the preliminary steps of nanoparticle development and characterization. At the beginning, the main barriers of the eye and the different administration routes are resumed, followed by a general description of the advantages of the employment of nanoparticles for ocular topical administration. Subsequently, the preformulative steps are discussed, deepening the choice of raw materials and determining the quantitative composition. Then, a detailed report of the physicochemical and technological characterization of nanoparticles is presented, analyzing the most relevant tests that should be performed on nanoparticles to verify their properties and the requisites (both mandatory and suggested) demanded by regulatory agencies. In conclusion, some preliminary noncellular in vitro evaluation methods are described. Studies from in vitro cellular assays to in vivo tests will be discussed in a separate (part 2) review paper. Hence, this overview aims to offer a comprehensive tool to guide researchers in the choice of the most relevant studies to develop a nanoplatform for ophthalmic drug administration.

Enhancing the hypotensive effect of latanoprost by combining synthetic phosphatidylcholine liposomes with hyaluronic acid and osmoprotective agents

The first line of glaucoma treatment focuses on reducing intraocular pressure (IOP) through the prescription of topical prostaglandin analogues, such as latanoprost (LAT). Topical ophthalmic medicines have low bioavailability due to their rapid elimination from the ocular surface. Nanotechnology offers innovative ways of enhancing the ocular bioavailability of antiglaucoma agents while reducing administration frequency. This study aims to combine LAT-loaded synthetic phosphatidylcholine liposomes with hyaluronic acid (0.2% w/v) and the osmoprotectants betaine (0.40% w/v) and leucine (0.90% w/v) (LAT-HA-LIP) to extend the hypotensive effect of LAT while protecting the ocular surface. LAT-HA-LIP was prepared as a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-phosphocholine, cholesterol and α-tocopherol acetate. LAT-HA-LIP exhibited high drug-loading capacity (104.52 ± 4.10%), unimodal vesicle sizes (195.14 ± 14.34 nm) and a zeta potential of -13.96 ± 0.78 mV. LAT-HA-LIP was isotonic (284.00 ± 1.41 mOsm L-1), had neutral pH (7.63 ± 0.01) and had suitable surface tension (44.07 ± 2.70 mN m-1) and viscosity (2.69 ± 0.15 mPa s-1) for topical ophthalmic administration. LAT-HA-LIP exhibited optimal in vitro tolerance in human corneal and conjunctival epithelial cells. No signs of ocular alteration or discomfort were observed when LAT-HA-LIP was instilled in albino male New Zealand rabbits. Hypotensive studies revealed that, after a single eye drop, the effect of LAT-HA-LIP lasted 24 h longer than that of a marketed formulation and that relative ocular bioavailability was almost three times higher (p < 0.001). These findings indicate the potential ocular protection and hypotensive effect LAT-HA-LIP offers in glaucoma treatment.

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.

Optimizing Mucoadhesive Film-Forming Spray for Efficient Oral Delivery of Fluconazole in Candidiasis Treatment

Buccal candidiasis has become increasingly prevalent in recent years, with Candida albicans being the primary causative organism. While systemic fluconazole is an effective treatment, its use is associated with adverse effects such as gastric upset, hepatic failure, and potential drug interactions. Therefore, the development of local fluconazole treatment presents a promising solution to these challenges. This study aimed to formulate an efficient local mucoadhesive film-forming spray for the targeted delivery of fluconazole in the treatment of oral candidiasis. The investigation involved the use of three polymers (hyaluronic acid, polyvinyl alcohol, and xanthan gum) both individually and in combination to identify the most effective formulation. Various tests were conducted to characterize 13 formulations prepared using these polymers, including UV-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), content assay, drying time and film formation, viscosity determination, determination of the mucoadhesion strength by turbidimetric methods, drug release study, in-vitro anticandida activity, histological irritation analysis, and stability study. The optimum formula F11, comprised polyvinyl alcohol for its superior mechanical properties and film-forming capabilities, hyaluronic acid, and xanthan gum in combination, exhibiting synergistic mucoadhesive strength. This optimal formulation demonstrated maximum mucoadhesion, rapid film formation, an acceptable spray angle, and controlled release. Furthermore, the optimum formula underwent additional evaluations for in vitro anti-Candida activity, in vivo irritancy assessments, and stability studies, all of which yielded satisfactory results. These findings support the potential of the optimum formula as a straightforward and efficient spray formulation for the treatment of oral candidiasis.

Scanning Electron Microscopy (SEM) Evaluation of the Ultrastructural Effects on Conjunctival Epithelial Cells of a New Multiple-Action Artificial Tear Containing Cross-Linked Hyaluronic Acid, Cationic Liposomes and Trehalose

The authors performed an ex vivo and in vivo evaluation of the ultrastructural effects on the conjunctival epithelial cells of a new multiple-action tear substitute containing cross-linked hyaluronic acid, lipids and trehalose (Trimix®), using scanning electron microscopy (SEM) with conjunctival impression cytology. The ex vivo study highlights the persistence and distribution of the product at 5 and 60 min on a monolayer of conjunctival epithelial cells and an increase in microvilli density at the 60 min evaluation. In vivo examination was conducted on three subjects with different grades of ocular surface inflammation, treated with one drop of the product twice daily for thirty days. At the baseline (T0) and twelve hours after the last administration of the tear drop (T30), impression cytology of the upper bulbar conjunctiva for SEM evaluation of conjunctival epithelial cells was carried out. Slit lamp examination (SLE), corneal and conjunctival Fluotest, tear film break-up time (TBUT), and ocular surface disease index (OSDI) questionnaires were also performed to correlate the ultrastructural results with the clinical findings. After 30 days of treatment, a significant improvement in all clinical and symptomatic parameters and in the condition of the ocular surface was detected, with microvillar regeneration and strengthening in all the patients, and a complete restoration in 2/3 of them. The persistence and distribution of the product on the epithelial cells was also noted 12 h after the last administration. The results, therefore, suggest a marked epitheliotropic effect along with a high residence time of the tear substitute.

3D Bioprinting with Visible Light Cross-Linkable Mucin-Hyaluronic Acid Composite Bioink for Lung Tissue Engineering

3D printing can revolutionize personalized medicine by allowing cost-effective, customized tissue-engineering constructs. However, the limited availability and diversity of biopolymeric hydrogels restrict the variety and applications of bioinks. In this study, we introduce a composite bioink for 3D bioprinting, combining a photo-cross-linkable derivative of Mucin (Mu) called Methacrylated Mucin (MuMA) and Hyaluronic acid (HA). The less explored Mucin is responsible for the hydrogel nature of mucus and holds the potential to be used as a bioink material because of its plethora of features. HA, a crucial extracellular matrix component, is mucoadhesive and enhances ink viscosity and printability. Photo-cross-linking with 405 nm light stabilizes the printed scaffolds without damaging cells. Rheological tests reveal shear-thinning behavior, aiding cell protection during printing and improved MuMA bioink viscosity by adding HA. The printed structures exhibited porous behavior conducive to nutrient transport and cell migration. After 4 weeks in phosphate-buffered saline, the scaffolds retain 70% of their mass, highlighting stability. Biocompatibility tests with lung epithelial cells (L-132) confirm cell attachment and growth, suggesting suitability for lung tissue engineering. It is envisioned that the versatility of bioink could lead to significant advancements in lung tissue engineering and various other biomedical applications.

Efficacy assessment of liposome crosslinked hyaluronic acid and standard hyaluronic acid eye drops for dry eye disease management: a comparative study employing the ocular surface analyzer and subjective questionnaires

Introduction

Dry eye disease (DED) is a prevalent condition causing ocular discomfort and visual disturbances, often managed with artificial tears. This study aimed to assess and compare the efficacy of eye drops containing Crosslinked Hyaluronic Acid (CHA) with liposomes and crocin and standard Hyaluronic Acid (HA) for DED management.

Methods

A single-blind, longitudinal study was conducted on 24 participants (48 eyes), randomized to receive one of the two treatments. Ocular health measures, including the ocular surface disease index (OSDI) and the standard patient evaluation of eye dryness (SPEED) scores, were assessed at baseline and 6 weeks post-treatment using the Ocular Surface Analyzer.

Results

CHA achieved a lipid layer thickness increase of 1.29 ± 1.08 Guillon pattern degree (p < 0.01), FNIBUT increase 0.64 ± 0.77 s (p < 0.01), MNIBUT increase1.28 ± 4.74 s (p = 0.19), OSDI decrease 11.72 ± 6.73 score points (p < 0.01) and SPEED decrease 1.16 ± 5.05 score points (p = 0.27). Significant reductions in the OSDI and SPEED scores post-treatment were observed with both treatments, indicating their effectiveness.

Conclusion

CHA with liposomes exhibits superior efficacy compared to standard HA eye drops in the management of DED. These findings highlight the potential for personalized treatment strategies incorporating CHA, indicating a more effective approach to DED management. However, further research is required to validate these results and investigate the long-term effects, which may pave the way for a data-driven and optimized approach to managing DED.

Trehalose and Dry Eye Disease: A Comprehensive Systematic Review of Randomized Controlled Trials

The purpose of the research project was to extensively review the efficacy and safety of a trehalose tear-substitute treatment in cases of dry eye disease (DED). A systematic review that included only full-length randomized controlled studies (RCTs) reporting the effects of trehalose tear-substitute treatment in three databases, PubMed, Scopus and Web of Science, was performed according to the PRISMA statement. The search period included papers published before 8 August 2023. The Cochrane risk-of-bias tool was used to analyze the quality of the studies selected. A total of 10 RCTs were included in this systematic review. Trehalose tear-substitute treatments achieved a higher improvement than did control group interventions in all reported variables. The mean differences between both groups were in favor of trehalose, and were as follows: ocular surface disease index (OSDI) questionnaire score of -8.5 ± 7 points, tear film breakup time (TBUT) of 1.9 ± 1 s, tear film thickness (TFT) of 0.25 ± 0.1 μm, tear meniscus height (TMH) of 0.02 ± 0.02 mm, Schirmer test (ST) of 0.8 ± 1.4 mm, corneal fluorescein staining (CFS) of -0.7 ± 0.1 points and visual acuity (VA) of 0.3 ± 2.1 letters. No adverse events after trehalose tear-substitute treatments were reported. Trehalose tear substitutes are a safe and effective treatment for DED. Therefore, trehalose tear substitutes should be recommended for patients with dry eye disease. In addition, there is specific evidence to support its use in the preoperative cataract surgery period.