A research team formed by scientists of the Medical University (MedUni) of Vienna and Harvard Medical School were able to repair the lack of hair cells in the inner ear caused by a genetic defect, in an animal model.

So far, researchers have found more than 300 genetic mutations associated with this condition. As hair cells are the sensory receptors of the auditory system, it can result in severe hearing impediment or hearing loss.

Of these defects, genetic mutations in GJB2 and GJB6 are the most common cause of congenital hearing loss. The first mutation alters the proper functioning of a protein called gap junction beta 2, more commonly known as connexin 26. Without sufficient levels of Connexin 26, the potassium flow from hair cells in the cochlea is disrupted, resulting in extremely high levels of potassium in the Corti s organ, leading to the profound sensorineural hearing loss.

Cochlea implants are currently used for partially restoring the hearing of people congenital hearing loss;  “however, these electronic implants with their twelve electrodes cannot 100% replace the more than 3,000 hair cells in the inner ear, which give as much finer hearing,” says Wolfgang Gstöttner, Head of the Department of Otorhinolaryngology at MedUni Vienna.

This is the first time a group of scientists have been able to introduce “repair genes” into the hair cells, to make them start working again. In the study, published in Nature Biotechnology, the researchers used a modified, non-pathogenic adeno-associated virus (Anc80L65), as a vehicle to deliver genes into the ear (as a “Trojan Horse”) to restore the functionality of the damaged hair cells.

Surprisingly, the treatment were not only beneficial to restore inner hair cells function, it also benefited 90% of outer hair cells. This resulted in a significant amplification function in the inner ear.

Now, the group of researchers led by Lukas Landegger would need to perform further studies to determine the tolerability of the vector, to be able to do clinical trials.

 

Source: Science Daily