If drugs that restore hearing become reality, this tiny pump device could deliver them into the ear

Advances in gene therapy and regenerative medicine are challenging the notion that hearing loss is permanent. A number of research groups and drug companies are busy working on drugs that would restore damaged sensory cells in the ear. Meanwhile, biomedical engineers at Draper Laboratories and Massachusetts Eye and Ear Infirmary are thinking one step ahead. […]

Advances in gene therapy and regenerative medicine are challenging the notion that hearing loss is permanent. A number of research groups and drug companies are busy working on drugs that would restore damaged sensory cells in the ear.

Meanwhile, biomedical engineers at Draper Laboratories and Massachusetts Eye and Ear Infirmary are thinking one step ahead.

They’ve spent several years working on a miniature, implantable drug delivery device that would repeatedly and precisely inject controlled doses of those drugs right where they need to go, into the fluid of the inner ear.

Described in the Feb. 21 issue of Lab on a Chip, the device uses a low-power microactuator to control a tiny drug pump that provides pumping to and from the cochlea. “The inner ear is very small; you would mount this behind the ear and thread tubing into the ear,” explained Jeff Borenstein, one of the Draper biomedical engineers working on the project.

Tiny, hair-like cells in the inner ear are what help convert sound vibrations from the middle ear into electrical signals that are then sent to the brain. Deterioration of those cells, either by age, repeated exposure to loud noises, certain toxic medications or other factors, is a common cause of hearing loss.

In humans, these cells don’t regenerate by themselves. But a number of researchers and companies, including Audion Therapeutics and Sound Pharmaceuticals, believe those cells can be coaxed to regrow.

Hearing aids and cochlear implants used now are helpful for amplifying sounds for people who experience hearing loss, but they don’t actually restore hearing by addressing the cause of the loss, Borenstein said. The drug treatments in development have potential to do that. But the problem then becomes, how do you deliver the drugs?

“There’s not going to be an oral medicine, because there’s a barrier between the blood and the cochlea (the part of the inner ear where the cells are),” he explained. “Patients would have to come into the a clinic and have injections in their ear. If you could implant a device, that would enable precise and controlled delivery over a period of time. Most people believe that regeneration treatment will take time, not just a few days but a few weeks or months.”

He hopes automated, controlled drug delivery could also eliminate the need for frequent office visits, prevent systemic drug side effects and improve patient adherence.

The project has so far been funded by an NIH grant, which Borenstein said will take it to the point where it’s ready for clinical trials, at which point it would hopefully partner with a pharmaceutical company. In the meantime, the researchers are also working on an animal model of the device that they think pharmaceutical companies could use in preclinical studies of their potential drug treatments.

Draper Laboratories is a nonprofit R&D lab based in Boston. The Massachusetts Eye and Ear Infirmary is a Harvard Medical School teaching hospital.