Nanotechnology and the treatment of inner ear diseases

Inner ear diseases such as sensorineural hearing loss and vertigo that cause degeneration of sensory-neural transducer epithelial cells and nerve cells are extremely common and significantly disabling conditions for which there are almost no effective remedies to date. Efforts are being made to produce agents that could prevent injury, limit its extent, and repair injury or regenerate new end organ and neural cells. These promising drugs or gene therapies may require local administration to the inner ear and even cell-specific targeting to provide adequate effective doses without systemic toxicity or side effects. Delivery of agents may require controlled or sustained release into the inner ear fluids, cellular cytoplasm, or nucleus of targeted cells. A number of classes of nanoparticles have been investigated that demonstrate the potential for accomplishing these challenging tasks. The strategies and experience to date for functionalizing nanoparticles for inner ear delivery and intracellular release of therapeutic agent into targeted cells will be reviewed in this article.