Pioneering nanotech approach to help people hear

Around 50 million EU citizens are deaf or hard of hearing. The EU-funded NANOEAR project has built up knowledge and processes that could improve their ability to hear. The results include a novel nanoparticle-based system with the potential to restore hearing, repair tissue and increase performance of cochlear implants. A nano-hearing implant could be available within 10 years.

The starting point for NANOEAR was studies suggesting that stimulating the inner ear nerve cells improves the function of cochlear implants. This can be done using nerve growth factor – a small protein. An alternative approach, also shown to improve the function of the inner ear, is to use novel genes to stimulate re-growth of the outer hair cells.

Repair and restore

Inspired by these developments, the NANOEAR team set out to create tools to repair cellular injury, restore tissue growth and induce cellular regeneration in the inner ear. Over five-years the team took huge steps towards reaching this goal, developing several nanoparticle carriers to transport therapeutic agents, such as drugs and genes, into the inner ear. They also created several so-called multifunctional nanoparticles (MFNPs) able to target selected tissue and release drugs in a controlled manner.

These MFNPs contain peptides (amino acids) to enhance internalisation to cells and transfection to nuclei. They are also invisible to the immune system so can escape detection.

“Traditional drugs are not able to pass through the tight membranes separating the middle ear from the inner ear,” explains project coordinator Dr IImari Pyykkö of the University of Tampere in Finland. “During NANOEAR we demonstrated that passage to the inner ear is in fact possible with nanoparticles that can carry drugs and target specific cells.”

The team carried out unprecedented MRI-imaging of the human inner ear by adding contrast agents to the nanoparticles, which made it possible to trace them in the body. This process gave much more detail of the ear than was previously possible.

This imaging also showed that the oval window membrane is a very effective pathway to the inner ear; not the round window as was previously thought.

A new implant for the inner ear?

Imaging and drug delivery are not the project’s only achievements. NANOEAR, which ended in October 2011, also laid the groundwork for developing a radically new cochlear implant, which is today undergoing further development in another project. It can be expected on the market within the next 10 years.

“We are currently trying to improve the cochlear implant by allowing the nerve endings to grow to the electrodes,” explains Dr Pyykkö.

NANOEAR has resulted in several patents, mainly in electrode technology and drug incorporation, and some of the partners aim to produce prototypes for human use under a new EU-funded project, known as NanoCI. Project partners are currently in the process of establishing joint ventures with the pharmaceutical industry to commercialise the nanodelivery items. The carrier system could also have many other applications within regenerative medicine.

Photo: © Kalim - Fotolia