Using gene expression data from different cell types in the inner ear and in the brain, researchers from a current study were able to identify the cell types having a major contribution to hearing loss.
Image credit: Pxhere, CC0 Public Domain
While the findings confirm that hearing loss does not derive from the brain, results show that it mainly originates from a distinct compartment in the cochlea, called the stria vascularis, which is the “powerhouse” of the inner ear.
Recent global estimates reveal that more than 2 .4 billion individuals will suffer from hearing loss by 2050. Genetic studies have linked several genes to hearing loss, each of these contributing to a small part of the risk to develop the disorder. It has been hypothesized since the 1970’s, that stria vascularis may play a role in hearing loss in humans, but the molecular evidence for this was missing until today.
“The findings in this study are important because it points at where research should be geared to provide better rehabilitation strategies for people with hearing loss. Researchers have mainly focused their efforts on the sensory hair cells, or the auditory neurons within the ear, with attempts to restore their function or to regenerate the missing cells. However, this may not prove useful if the powerhouse of the ear is dysfunctional”, says co-main author Christopher R. Cederroth, Associate Professor at the Department of Physiology and Pharmacology at Karolinska Institutet.
The study relied on collaboration between multiple centers and biobanks from Europe in the United States to gather human genetic data, which was then combined with a very large set of cellular data originating from mouse studies. Karolinska Institutet was a lead coordinating institution together with King’s College London and Erasmus MC.
“Many of the genes that were identified in humans have already been validated in mice, which shows the high translational validity of these animal models. This was crucial since it is very difficult to access human inner ear samples”, Christopher Cederroth says. “Now that we know what cell type is important to focus our research on, future steps will be to address on how to target this structure with innovative therapeutic approaches in order to improve its function, in particular in individuals with age-related hearing loss”.
Source: Karolinska Institutet