Biocompatibility of glycerol monooleate nanoparticles as tested on inner ear cells

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.

Nanomaterials for Inner Ear Diseases: Challenges, Limitations and Opportunities

The inner ear is located deep in the temporal bone and has a complex anatomy. It is difficult to observe and obtain pathological tissues directly. Therefore, the diagnosis and treatment of inner ear diseases have always been a major clinical problem. The onset of inner ear disease can be accompanied by symptoms such as hearing loss, dizziness and tinnitus, which seriously affect people's lives. Nanoparticles have the characteristics of small size, high bioavailability and strong plasticity. With the development of related research on nanoparticles in inner ear diseases, nanoparticles have gradually become a research hotspot in inner ear diseases. This review briefly summarizes the research progress, opportunities and challenges of the application of nanoparticles in inner ear diseases.

Hydrogen peroxide toxicity on auditory cells: An in vitro study

In recent decades, interest has increased in the role of reactive oxygen species (ROS) in health and disease. The ROS are key causative factors in several hearing loss pathologies including ototoxicity, noise trauma, cochlear ageing and ischemic injury. In order to investigate ROS effects on inner ear cells and counteract them, we developed an in vitro model of oxidative stress by exposing the inner ear cell line OC-k3 to hydrogen peroxide (H₂O₂) at concentrations able to affect in vivo cellular components but allowing cell survival. The treatment with high concentrations (20 and 30 μM) resulted in reduction of cell viability, activation of apoptosis/necrosis and alteration of morphology, cell cycle progression and antioxidant defences. The ROS effects in inner ear cells are difficult to assess in vivo. Organocultures may provide preservation of tissue architecture but involve ethical issues and can be used only for a limited time. An in vitro model that could be commercially available and easy to handle is necessary to investigate inner ear oxidative stress and the ways to counteract it. The OC-k3 line is a suitable in vitro model to study ROS effects on inner ear cells because the observed cell alterations and damages were similar to those reported in studies investigating ROS effects of ototoxic drugs, noise trauma and cochlear ageing.

Lithium niobate nanoparticles as biofunctional interface material for inner ear devices

Sensorineural hearing loss (SNHL) affects the inner ear compartment and can be caused by different factors. Usually, the lack, death, or malfunction of sensory cells deputed to transduction of mechanic-into-electric signals leads to SNHL. To date, the therapeutic option for patients impaired by severe or profound SNHL is the cochlear implant (CI), a high-tech electronic device replacing the entire cochlear function. Piezoelectric materials have catalyzed attention to stimulate the auditory neurons by simply mimicking the function of the cochlear sensory epithelium. In this study, the authors investigated lithium niobate (LiNbO₃) as a potential candidate material for next generation CIs. LiNbO₃ nanoparticles resulted otocompatible with inner ear cells in vitro, had a pronounced immunomodulatory activity, enhanced human beta-defensin in epithelial cells, and showed direct antibacterial activity against P. aeruginosa. Moreover, LiNbO₃ nanoparticles were incorporated into poly(vinylidene fluoride-trifluoro ethylene) fibers via electrospinning, which enhanced the piezoelectric response. Finally, the resulting fibrous composite structures support human neural-like cell growth in vitro, thus showing promising features to be used in new inner ear devices.