A TECHNIQUE that stimulates auditory nerve cell endings to resprout could allow more people to recover lost hearing.
In some cases of deafness, cochlear implants can restore hearing by bypassing damaged hair cells and directly stimulating the auditory nerve. But the nerve鈥檚 health depends on growth factors produced by hair cells, so it tends to deteriorate too, limiting the effectiveness of implants.
Graeme Clark of the Bionic Ear Institute in Melbourne, Australia, and colleagues infused growth factors called neurotrophin 3 and BDNF into the inner ears of guinea pigs whose hair cells had been destroyed. This stopped nerve cells from dying and caused nerves to regrow their branch-like extensions within a month. The growth factors were used several weeks after the hair cells had been destroyed, to better mimic the condition of people who have been deaf for years before they get a cochlear implant.
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There are several hurdles to overcome before the technique can be used clinically, including getting nerve extensions to grow in an orderly fashion. The team hopes to use a biodegradable scaffold impregnated with growth factors to direct nerve growth towards the implant. Clark discussed the work last week after receiving the Prime Minister鈥檚 Prize for Science in Canberra for his work on cochlear implants.