Hearing could be restored to millions of people suffering from progressive deafness by transplanting part of their brain into their ear, according to research.
One in ten of the world's population will suffer hearing loss as aging and overstimulation damages hair cells in the inner ear.
The cell loss is irreversible because the cells have a limited capacity to regenerate.
However, a new study suggests that the ependymal layer of the lateral ventricle of the brain contains stem cells which share characteristics with inner ear hair cells and which have the potential to reproduce.
According to the scientists, these cells could potentially be transplanted from a person's brain into their ear, where they would undergo a functional switch to enable them to replace the damaged ones.
A secondary effect of inner ear hair cell (HC) loss is the gradual degeneration and death of spiral ganglia neurons (SGNs), the study said.
As the production of new HCs and SGNs is a rare event, "considerable efforts have been made to identify a renewable cell source able to reconstruct damaged inner ears".
The authors of the study, published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), said: "We surmise that cells of the adult forebrain germinal zone might be potential candidate cells to be used autologously for the replacement of non-renewable HCs and SGNs."