Stem cell progress towards treating deafness

US Scientists have produced mouse inner ear hair cells using stem cells, paving the way for a cure for deafness and other related balance disorders.

Two types of mouse stem cells were used to create the inner ear hair cells: embryonic stem cells and iPS cells (induced pluripotent stem cells) reprogrammed from skin tissue.

When the resulting cells were viewed under an electron microscope, as well as mechanically stimulated, they resembled those produced by young hair cells. 'They really looked like they were more or less taken out of the ear', said the lead researcher, Professor Stefan Heller, from Stanford University School of Medicine, US.

Scientists hope to take the technology for creating mouse ear hair cells and apply it to humans. Age-related hearing loss affects half of Britons aged 60 and over and there is currently no cure. Furthermore there are around nine million deaf people in Britain alone, many of whom lost their hearing due to hair cell loss.

'If this works, we would be able to take, for example, a skin cell from a human patient and convert this cell first into iPS cells, then into inner ear cells. We could then probe and analyse hair cells generated from patients directly to investigate the source of their dysfunction', said Professor Heller. 'These cells could then be used to test for chemical stimuli which would enable the body to grow more hair cells, or eventually, they could be transplanted to reverse hearing loss'.

However, Professor Heller warned that much research is needed before these cells can be used, and the techniques for such use are still a decade away. 'I am not saying that it will be unfeasible, but it is certainly not around the corner', he said.

Hearing remains mysterious compared to other human senses, such as vision, because the inner ear is less accessible, and still little is known about how the inner ear cells transform acoustic waves into neural signals that we interpret as sound.

Inner ear hair cells are specialised cells which deform when sound waves hit them and are crucial to hearing. Humans have about 15,000 hair cells in each ear, which do not regenerate when damaged.

The study was reported in the journal Cell.