Comparison of cytotoxicity and wound healing effect of carboxymethylcellulose and hyaluronic acid on human corneal epithelial cells

Role of Mesenchymal Stem Cell-Derived Conditioned Medium in Modulating the Benzalkonium Chloride-Induced Cytotoxic Effects in Cultured Corneal Epithelial Cells In Vitro

PURPOSE

Benzalkonium chloride (BAK) is a common preservative in ophthalmic formulations that causes cytotoxic damage to the corneal epithelial cells. This study aims to explore the role of mesenchymal stem cell (MSC)-derived conditioned medium in modulating the BAK-induced cytotoxic effects in cultured human corneal epithelial cells (HCECs) as a cell-free therapeutic agent.

METHODS

The in vitro cultured HCECs derived from a HCE cell line were treated with BAK (0.001% and 0.005%, diluted in DMEM/F12, v/v) for 15 min, washed with 1xPBS, and allowed to recover for 24 h in human bone marrow MSC-derived conditioned medium (MSC-CM: undiluted (100%) and diluted (50%, v/v)). On the other hand, HCECs were co-incubated with BAK (0.005%, v/v) and MSC-CM (100% and 50%, v/v) for 24 h. The HCEC-derived conditioned medium (HCE-CM) was used as an optimal control for MSC-CM, whereas HCECs cultured in DMEM/F12 were used as a control. The DMEM/F12 was used as the base medium for the culture of HCECs and preparation of HCE- and MSC-CM. The role of MSC-CM in modulating the metabolic activity, cell death, epithelial repair, and proliferation, in BAK-treated HCECs was evaluated using MTT assay, Propidium iodide staining, scratch assay, and Ki-67 staining, respectively.

RESULTS

Compared to the control, recovery of BAK-treated (0.001% and 0.005%, for 15 min) HCECs in MSC-CM showed significantly reduced cell death with enhanced metabolic activity, epithelial repair, and proliferation. However, in comparison with HCE-CM, the beneficial effects of MSC-CM were predominantly observed at lower BAK concentration (0.001%, for 15 min). Whereas the co-incubation of BAK (0.005%) and MSC-CM for a longer duration (24 h) was marginally beneficial.

CONCLUSIONS

Our results suggest that the MSC-CM is effective in modulating the BAK-induced cell death, retardation of metabolic activity and proliferation in cultured HCECs, particularly at lower concentration (0.001%) and shorter exposure (15 min) of BAK.

Preclinical evaluation of the safety and effectiveness of a new bioartificial cornea

Cross-linking agents are frequently used to restore corneal properties after decellularization, and it is especially important to select an appropriate method to avoid excessive cross-linking. In addition, how to promote wound healing and how to improve scar formation require further investigation. To ensure the safety and efficacy of animal-derived products, we designed bioartificial corneas (BACs) according to the criteria for Class III medical devices. Our BACs do not require cross-linking agents and increase mechanical strength via self-cross-linking of aldehyde-modified hyaluronic acid (AHA) and carboxymethyl chitosan (CMC) on the surface of decellularized porcine corneas (DPCs). The results showed that the BACs had good biocompatibility and transparency, and the modification enhanced their antibacterial and anti-inflammatory properties in vitro. Preclinical animal studies showed that the BACs can rapidly regenerate the epithelium and restore vision within a month. After 3 months, the BACs were gradually filled with epithelial, stromal, and neuronal cells, and after 6 months, their transparency and histology were almost normal. In addition, side effects such as corneal neovascularization, conjunctival hyperemia, and ciliary body hyperemia rarely occur in vivo. Therefore, these BACs show promise for clinical application for the treatment of infectious corneal ulcers and as a temporary covering for corneal perforations to achieve the more time.

Physicochemical Stability of a Novel Tacrolimus Ophthalmic Formulation for the Treatment of Ophthalmic Inflammatory Diseases

Tacrolimus is an immunosuppressant used to treat a large variety of inflammatory or immunity-mediated ophthalmic diseases. However, there are currently no commercial industrial forms available that can provide relief to patients. Various ophthalmic formulations have been reported in the literature, but their stability has only been tested over short periods. The objective of this study was to evaluate the physicochemical stability of a preservative-free tacrolimus formulation (0.2 and 1 mg/mL) at three storage temperatures (5 °C, 25 °C and 35 °C) for up to nine months in a multidose eyedropper. Analyses performed were the following: visual inspection and chromaticity, turbidity, viscosity, size of micelles, osmolality and pH measurements, tacrolimus quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. In an in-use study, tacrolimus quantification was also performed on the drops emitted from the eyedroppers. All tested parameters remained stable during the nine month period when the eyedrops were stored at 5 °C. However, during storage at 25 °C and 35 °C, several signs of chemical instability were detected. Furthermore, a leachable compound originating from a silicone part of the eyedropper was detected during the in-use assay. Overall, the 0.2 mg/mL and 1 mg/mL tacrolimus ophthalmic solutions were physicochemically stable for up to nine months when stored at 5 °C.

Extraction and characterization of an exopolysaccharide from a marine bacterium

The marine bacterial exopolysaccharides (EPS) have transfigured the biotech sector with their myriad applications and prospects. This work was carried out to characterize and analyze the functional and biochemical properties of an EPS (EPS-DR3A) produced by a marine bacterium, Pseudoalteromonas sp. YU16-DR3A. The bacterium was cultured in Zobell marine broth for the production of EPS. The extracted EPS designated as EPS-DR3A was composed of 69% carbohydrates and 7.6% proteins with a molecular weight of 20 kDa. FT-IR spectra showed the presence of different functional groups. The monosaccharide analysis performed using GC-MS showed the presence of fucose, erythrotetrose, ribose, and glucose as monomers. EPS-DR3A showed excellent emulsifying activity against the tested hydrocarbons and food oils with stable emulsions. Rheological analysis of EPS-DR3A revealed the pseudoplastic behavior. The EPS-DR3A displayed good thermal stability with a degradation temperature of 249 °C and a melting point at 322 °C. Further, it had the ability to scavenge DPPH and nitric oxide free radicals with good total antioxidant activity. The in vitro biocompatibility study of EPS-DR3A showed high degree of biocompatibility with human dermal fibroblast cells at the tested concentrations. Taken together, the findings such as thermostability, emulsifying activity, pseudoplasticity, antioxidant activity, and biocompatibility of EPS-DR3A make this biomolecule an important candidate for a wide range of biomedical applications.

A combination of CMC and α-MSH inhibited ROS activated NLRP3 inflammasome in hyperosmolarity stressed HCECs and scopolamine-induced dry eye rats

An important mechanism involved in dry eye (DE) is the association between tear hyperosmolarity and inflammation severity. Inflammation in DE might be mediated by the NLRP3 inflammasome, which activated by exposure to reactive oxygen species (ROS). A combination of carboxymethylcellulose (CMC) and α-melanocyte stimulating hormone (α-MSH) may influence DE through this mechanism, thus avoiding defects of signal drug. In this study, we assessed whether treatment comprising CMC combined with α-MSH could ameliorate ocular surface function; we found that it promoted tear secretion, reduced the density of fluorescein sodium staining, enhanced the number of conjunctival goblet cells, and reduced the number of corneal apoptotic cells. Investigation of the underlying mechanism suggested that the synergistic effect of combined treatment alleviated DE inflammation through reduction of ROS level and inhibition of the NLRP3 inflammasome in human corneal epithelial cells. These findings indicate that combined CMC + α-MSH treatment could ameliorate lesions and restore ocular surface function in patients with DE through reduction of ROS level and inhibition of NLRP3 signalling.

Comparison of cytotoxicities and anti-allergic effects of topical ocular dual-action anti-allergic agents

Background

To investigate the cytotoxicities of the topical ocular dual-action anti-allergic agents (alcaftadine 0.25%, bepotastine besilate 1.5%, and olopatadine HCL 0.1%) on human corneal epithelial cells (HCECs) and their anti-allergic effects on cultured conjunctival epithelial cells.

Methods

A Methylthiazolyltetrazolium(MTT)-based calorimetric assay was used to assess cytotoxicities using HCECs at concentrations of 10, 20 or 30% for exposure durations of 30 min, 1 h, 2 h, 12 h or 24 h. Cellular morphologies were evaluated by inverted phase-contrast and electron microscopy. Wound widths were measured 2 h, 18 h, or 24 h after confluent HCECs monolayers were scratched. Realtime PCR was used to quantify anti-allergic effects on cultured human conjunctival cells, in which allergic reactions were induced by treating them with Aspergillus antigen.

Results

Cell viabilities decreased in time- and concentration-dependent manners. Cells were detached from dishes and showed microvilli loss, cytoplasmic vacuoles, and nuclear condensation when exposed to antiallergic agents; alcaftadine was found to be least cytotoxic. Alcaftadine treated HCECs monolayers showed the best wound healing followed by bepotastine and olopatadine (p < 0.0001). All agents significantly reduced the gene expressions of allergic cytokines (IL-5, IL-25, eotaxin, thymus and activation-regulated chemokine, and thymic stromal lymphopoietin) and alcaftadine had the greatest effect (p < 0.0001 in all cases).

Conclusions

Alcaftadine seems to have less side effects and better therapeutic effects than the other two anti-allergic agents tested. It may be more beneficial to use less toxic agents for patients with ocular surface risk factors or presumed symptoms of toxicity.

Oral Hyaluronic Acid Supplementation for the Treatment of Dry Eye Disease: A Pilot Study

Purpose

To evaluate the clinical efficacy of oral hyaluronic acid (HA) in patients with dry eye disease (DED).

Study Design

Prospective randomized controlled trial.

Methods

This trial enrolled 54 subjects and they were randomized into the study or control group. The inclusion criteria were as follows: (1) >18 years of age; (2) distance best-corrected visual acuity ≥ 20/40 Snellen equivalent in each eye; (3) IOP ≤ 21 mmHg in both eyes; (4) ocular surface disease index (OSDI) score of ≥18 and <65; (5) <10 seconds of tear break up time (TBUT); (6) >5 corneal spots of corneal fluorescein staining (CFS); and (7) ≤ 10 mm/5 min of the Schirmer test. All subjects were treated with a topical HA, and the study group was supplemented with oral HA. OSDI, TBUT, CFS, and the Schirmer test were evaluated for ocular surface parameters.

Results

24 patients were assigned in the study group. Significant improvement of OSDI, TBUT, and CFS was observed at 1 month and 3 months after oral HA administration in the study group. At baseline and follow-up at 1 and 3 months, OSDI scores were 61.8 ± 16.2, 47.3 ± 11.6, and 42.3 ± 9.1, respectively (P < 0.001). TBUT was improved after treatment for 1 month and 3 months (4.2 ± 1.1; P=0.005 and 4.7 ± 1.1; P < 0.012). There were also statistically significant improvements in the CSF (1.8 ± 1.0, 0.8 ± 0.7; P < 0.001) at baseline compared with those at 1 month.

Conclusions

A combined supplement of both oral and topical HA more efficiently improves corneal epithelial wound healing and related symptoms than topical HA alone, in DED.

In vitro safety and performance evaluation of a seawater solution enriched with copper, hyaluronic acid, and eucalyptus for nasal lavage

Background

The common cold is a viral infectious disease with symptoms such as runny nose, sore throat, and mainly, nasal congestion. State-of-the-art therapeutic approaches focus on alleviating the symptoms of this disease by non-invasive and simple-to-use methods. Nasal irrigation is one of the most accepted approaches to ease nasal congestion which, if left untreated, has a negative impact on the quality of life of patients.

Purpose

In this study, the safety and efficacy of a novel hypertonic seawater solution for nasal lavage enriched with hyaluronic acids, eucalyptus oil, copper, and manganese salts (Stérimar Stop & Protect Cold and Flu; SSPCF) have been investigated in vitro.

Methods

An in vitro 3D reconstituted human nasal epithelium tissue model, MucilAir™, has been used in this study to investigate the safety of SSPCF on nasal epithelium by measuring transepithelial electrical resistance (TEER), lactate dehydrogenase (LDH), and interleukin-8 (IL-8) secretion. The efficacy of SSPCF was measured by mucociliary clearance (MCC), ATP release, Alcian blue and aquaporin (AQP3) stainings.

Results

SSPCF treatment respected nasal epithelium tissue integrity and enhanced barrier function without inducing a cytotoxic response. Secreted LDH and IL-8 levels were similar to untreated controls. MCC rate was increased 2.5-fold and ATP release decreased 87% upon SSPCF treatment, indicating improved decongestion activity. SSPCF treatment after hypotonic stress helped recover cellular organization, as shown by Alcian blue and AQP3 staining assays.

Conclusion

SSPCF appears as a safe and effective nasal irrigation formula that may alleviate the symptoms associated with common cold such as nasal congestion.

Comparison of cytotoxicities and wound healing effects of diquafosol tetrasodium and hyaluronic acid on human corneal epithelial cells

This study aimed to compare the cellular toxicities of three clinically used dry eye treatments; 3% diquafosol tetrasodium and hyaluronic acid at 0.3 and 0.18%. A methyl thiazolyltetrazoiun (MTT)-based calorimetric assay was used to assess cellular proliferation and a lactate dehydrogenase (LDH) leakage assay to assess cytotoxicity, using Human corneal epithelial cells (HCECs) exposed to 3% diquafosol tetrasodium, 0.3% hyaluronic acid (HA), or 0.18% HA or 1, 6 or 24 h. Cellular morphology was evaluated by inverted phase-contrast light microscopy and electron microscopy, and wound widths were measured 24 h after confluent HCECs were scratched. Diquafosol had a significant, time-dependent, inhibitory effect on HCEC proliferation and cytotoxicity. HCECs treated with diquafosol detached more from the bottoms of dishes and damaged cells showed degenerative changes, such as, reduced numbers of microvilli, vacuole formation, and chromatin of the nuclear remnant condensed along the nuclear periphery. All significantly stimulated reepithelialization of HCECs scratched, which were less observed in diquafosol. Therefore, epithelial toxicity should be considered after long-term usage of diquafosol and in overdose cases, especially in dry eye patients with pre-existing punctated epithelial erosion.

Hyaluronate Acid-Dependent Protection and Enhanced Corneal Wound Healing against Oxidative Damage in Corneal Epithelial Cells

Purpose. To evaluate the effects and mechanism of exogenous hyaluronate (HA) in promoting corneal wound healing. Methods. Human corneal epithelial cells (HCECs) were incubated with different concentrations of HA to evaluate their efficiency in promoting cell migration and their modulation of repair factors. After inducing hyperosmolar conditions, the cell morphologies, cell apoptosis, and expression levels of TNF-α and MMP-9 were detected to assess the protective role of HA. Corneal epithelium-injured rat models were established to test the therapeutic effects of 0.3% HA. Then, the wound healing rates, the RNA expression levels of inflammatory cytokines, and repair factors were examined. Results. HCECs in the 0.03% and 0.3% HA groups showed fewer morphological alterations and lower rates of cell apoptosis following preincubation with HA under hyperosmolar conditions, as well as the expression levels of MMP-9 and TNF-α. In the rat model, the areas of fluorescein staining in the corneas of 0.3% HA group were significantly smaller than the control group. The expression levels of IL-1β and MMP-9 were decreased, while CD44 and FN were increased in the 0.3% HA group. Conclusion. HA enhanced corneal epithelial cell wound healing by promoting cell migration, upregulating repair responses, and suppressing inflammatory responses.