In most cases, deafness is caused by the loss of hair cells in the inner ear that convert acoustic vibrations into nerve signals. Patients compensate by using cochlear implants with electrodes that stimulate the auditory nerve. But 'bionic ears' don’t restore hearing to normal sensitivity. Now, researchers have upgraded the performance of cochlear implants in guinea pigs by using the devices to deliver gene therapy. Pictured is a CT scan of a guinea pig’s skull with a cochlear implant. Electrical pulses from the implant create tiny holes in target cells, enabling the delivery of a gene that stimulates growth of new auditory nerves. Sure enough, nerve cells grew toward the implant’s electrodes, restoring the intimate connection that had been missing. The result was a dramatic improvement in hearing. If the method works in humans, it could help deaf people to experience something closer to the sharpness of normal hearing.
Written by Daniel Cossins