Liquid Crystalline Nanoparticles Conjugated with Dexamethasone Prevent Cisplatin Ototoxicity In Vitro.

The conjugation of drugs with nanoparticles represents an innovative approach for controlled and targeted administration of therapeutic agents. Nanoparticle-based systems have been tested for the inner ear therapy, increasing the drug diffusion and being detected in all parts of the cochlea when locally applied near the round window. In this study, glycerol monooleate liquid crystalline NanoParticles were conjugated with Dexamethasone (NPD), a hydrophobic drug already used for inner ear treatments but defective in solubility and bioavailability. NPD has been tested in vitro in the cell line OC-k3, a model of sensory cells of the inner ear, and the therapeutic efficacy has been evaluated against cisplatin, a chemotherapeutic compound known to induce ototoxicity. After comparing the physical chemical characteristics of NPD to the equivalent naïve nanoparticles, an initial investigation was carried out into the nanoparticle's uptake in OC-k3 cells, which takes place within a few hours of treatment without causing toxic damage up to a concentration of 50 µg/mL. The NPD delivered the dexamethasone inside the cells at a significantly increased rate compared to the equivalent free drug administration, increasing the half-life of the therapeutic compound within the cell. Concerning the co-treatment with cisplatin, the NPD significantly lowered the cisplatin cytotoxicity after 48 h of administration, preventing cell apoptosis. To confirm this result, also cell morphology, cell cycle and glucocorticoids receptor expression were investigated. In conclusion, the NPD system has thus preliminarily shown the potential to improve the therapeutic efficacy of treatments delivered in the inner ear and prevent drug-induced ototoxicity.

Enhancing Resistance of Silk Fibroin Material to Enzymatic Degradation by Cross-Linking Both Crystalline and Amorphous Domains.

Silk fibroin (SF) membranes are finding widespread use as biomaterial scaffolds in a range of tissue engineering applications. The control over SF scaffold degradation kinetics is usually driven by the proportion of SF crystalline domains in the formulation, but membranes with a high ß-sheet content are brittle and still contain amorphous domains, which are highly susceptible to enzymatic degradation. In this work, photo-cross-linking of SF using a ruthenium-based method, and with the addition of glycerol, was used to generate robust and flexible SF membranes for long-term tissue engineering applications requiring slow degradation of the scaffolds. The resulting mechanical properties, protein secondary structure, and degradation rate were investigated. In addition, the cytocompatibility and versatility of porous micropatterning of SF films were assessed. The photo-cross-linking reduced the enzymatic degradation of SF in vitro without interfering with the ß-sheet content of the SF material, while adding glycerol to the composition grants flexibility to the membranes. By combining these methods, the membrane resistance to protease degradation was significantly enhanced compared to either method alone, and the SF mechanical properties were not impaired. We hypothesize that photo-cross-linking protects the SF amorphous regions from enzymatic degradation and complements the natural protection offered by ß-sheets in the crystalline region. Overall, this approach presents broad utility in tissue engineering applications that require a long-term degradation profile and mechanical support.

Tunable Biodegradable Silk-Based Memory Foams with Controlled Release of Antibiotics.

Sustained, local delivery of the antibiotic ciprofloxacin under different formats from porous silk protein-based memory foam systems was studied. Similarly, protease XIV was incorporated during processing to provide control of the degradation kinetics of the silk materials. In vitro antibiotic release studies combined with degradation assessments were utilized to assess the mechanisms and kinetics of release from the silk materials. The sequestered protease XIV affected the degradation profiles of the silk foams yet did not impact the release kinetics of the ciprofloxacin, which was controlled by solubility and diffusion of the drug. The ability to tune the release of ciprofloxacin between 1 and 200 days, combined with the option to modulate the degradation rate up to 80% in 2 weeks via incorporation of a protease, suggests utility for drug release devices. Further, we anticipate that this approach could also be extended to other medical implant needs and other drugs.

Biocompatibility of glycerol monooleate nanoparticles as tested on inner ear cells.

Sensorineural hearing loss due to aging, noise exposure, trauma or drug ototoxicity is irreversible because cochlear hair cells and neurons cannot regenerate. Recently, therapeutic strategies involving nanoparticles have been developed as innovative drug delivery systems. Thermodynamically stable liquid crystalline nanoparticles based on the polar lipid glycerol monooleate (GMO NP, cubosomes), nontoxic and able to encapsulate both hydrophilic and hydrophobic compounds, were produced and tested for biocompatibility in an immortalized Organ of Corti derived cell line (OC-k3), through cell viability and cytomorphological assays, and Western blot expression profiles of apoptotic markers. Overall, the GMO NP were biocompatible in OC-k3 at the doses and time tested, supporting previous data obtained in a neuronal cell line (PC12). The results encourage further tests on GMO NP-mediated drug release with improved target specificity and could be useful to develop innovative therapies against sensorineural hearing loss.

Evaluation of toxicity of glycerol monooleate nanoparticles on PC12 cell line.

An innovative approach to improve drug delivery is the use of glycerol monooleate nanoparticles. Numerous studies describe their high versatility, low toxicity and ability to carry relatively high loads of conjugated compounds including scarcely soluble ones, providing sustained drug release and increasing drug diffusion and half-life. Despite a growing interest in their potential use for therapeutic applications, there are surprisingly few literature data concerning the toxic effects of these nanoparticles at high concentrations in vitro and in vivo, and their effects on cell metabolism. We produced and characterized from a physical-chemical point of view glycerol monooleate nanoparticles and tested them on the PC12 cell line, a rat model of neuronal differentiation. The toxicity of these nanoparticles was evaluated by molecular methods on cell viability, cell cycle, nanoparticle uptake and induction of apoptosis. The results showed that glycerol monooleate nanoparticles up to 100 µg/mL had no toxic effects on PC12 cells, did not induce significant changes in the cell cycle nor cause apoptosis. The nanoparticles entered PC12 cells 8 h after treatment, successfully delivering the conjugate compound inside cells. Overall, glycerol monooleate nanoparticles did not exhibit significant toxicity on PC12 cell line in concentrations up to 100 µg/mL, supporting their therapeutic use as drug delivery systems.

Correction: Coenzyme Q10 plus Multivitamin Treatment Prevents Cisplatin Ototoxicity in Rats.

[This corrects the article DOI: 10.1371/journal.pone.0162106.].

Coenzyme Q10 plus Multivitamin Treatment Prevents Cisplatin Ototoxicity in Rats.

Cisplatin (Cpt) is known to induce a high level of oxidative stress, resulting in an increase of reactive oxygen species damaging the inner ear and causing hearing loss at high frequencies. Studies on animal models show that antioxidants may lower Cpt-induced ototoxicity. The aim of this study is to evaluate the ototoxic effects of two different protocols of Cpt administration in a Sprague-Dawley rat model, and to test in the same model the synergic protective effects of a solution of coenzyme Q10 terclatrate and Acuval 400®, a multivitamin supplement containing antioxidant agents and minerals (Acu-Qter). The Cpt was administered intraperitoneally in a single dose (14 mg/kg) or in three daily doses (4.6 mg/kg/day) to rats orally treated or untreated with Acu-Qter for 5 days. The auditory function was assessed by measuring auditory brainstem responses from 2 to 32 kHz at day 0 and 5 days after treatment. Similar hearing threshold and body weight alterations were observed in both Cpt administration protocols, but mortality reduced to zero when Cpt was administered in three daily doses. The Acu-Qter treatment was able to prevent and completely neutralize ototoxicity in rats treated with three daily Cpt doses, supporting the synergic protective effects of coenzyme Q terclatrate and Acuval 400® against Cpt-induced oxidative stress. The administration protocol involving three Cpt doses is more similar to common human chemotherapy protocols, therefore it appears more useful for long-term preclinical studies on ototoxicity prevention.

Efficient synthesis and biological evaluation of two modafinil analogues.

Non classical bioisosters of modafinil featuring interesting biological profile have been easily produced through replacement of the sulfoxide function with a carbonyl group and modification of the carboxylic acid amide functionality.