Hope for reversal of hearing loss

22 June 2006

A US study has raised hopes that one day researchers will be able to restore hair cells in the ears of people suffering from deafness.

Tiny hairs in the ear detect vibrations which the brain translates into sound, but once lost they cannot be replaced. However, a mouse study published in Nature has shown that certain cells taken from the inner ear can in fact differentiate into sensory hair cells.

In birds, hair cells that are damaged are replaced by new cells that grow from other neighbouring cells, restoring hearing within weeks. These nearby 'supporting cells' are present in mammals but do not replace hair cells once they are lost.

A team at the House Ear Institute in California developed a way of making these cells glow green in mice so they could separate out them from other types of cell. They then tested whether they would divide and differentiate in a petri dish environment designed to mimic the ear.

Cells from the ears of newborn mice were able to divide and differentiate into hair cells. In two-week old mice the cells had lost the ability to divide but were still able to differentiate.

The researchers discovered a gene called p27 was switched on in the majority of cells by 14 days, which halted the cell cycle and stopped them dividing. They said the gene could be a potential target for turning on cell division, replenishing cells and reversing hearing loss.

Source: news.bbc.co.uk
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