Hopes raised for deafness research

Damage to sensory hair cells, which can be regrown by birds, fish and amphibians but not generally by humans and other mammals, can cause deafness, tinnitus and balance problems.

Until now, research in this area has been difficult because the cells had to be taken from the internal ear, or created and then put into embryonic ears or grown via other tissues. But Zhengqing Hu and Jeffrey Corwin, from the Department of Neuroscience at the University of Virginia School of Medicine, have now managed successfully to create the cells "in vitro".

The two scientists developed a method of isolating cells from the inner ears of embryonic birds and perpetuating them in the lab.

They identified a critical transition in cell type that leads to the generation of hair cells.

When that transition was induced, the cultured cells turned into hair cells which were crowned by the characteristic "hair bundles" that detect sound and balance stimuli.

Other studies had managed to create the cells in the laboratory in the past but they then had to be transplanted into embryonic ears or by co-culturing with other tissues.

Hu and Corwin's work, revealed in the Proceedings of the National Academy of Sciences, is a step forward because no other cells or tissues were needed.

The avian inner ear cells they produced could be cultured and passaged for months, as well as frozen and expanded into large numbers, according to the report.

It is believed such a reliable source of hair cells should "substantially accelerate" research into hearing loss and other inner ear disorders.