Discovering a stem cell cure for deafness
Deafness is a major public health issue worldwide, with more than three million people in the UK alone enduring a moderate to profound hearing loss. The numbers rise to around 10 million if sufferers of mild impairments are included.
Current developments in stem cell technology led by Dr Marcelo Rivolta, from the University of Sheffield’s Department of Biomedical Science, could offer new hope for the treatment of auditory neuropathy, a common form of deafness in which the damage occurs at the level of the cochlear nerve.
Dr Rivolta has spent 10 years researching how to differentiate human embryonic stem cells into the two cell types that are essential for hearing: auditory neurons and the inner-ear hair cells that translate sound into electrical signals. He is also a member of the University’s Centre for Stem Cell Biology, which was the first laboratory to undertake research on human embryonic stem cells in the UK and has played a major role in training scientists in this dynamic field.
His research team converted human embryonic stem cells into cells similar to spiral ganglion neurons – the nerve cells which pass sounds into the brain. They then delicately injected them into the inner ears of deaf gerbils. The gerbils, on average, recovered 46 per cent of their hearing. The improvement was evident about four weeks after administering the cells and observed for 10 weeks. This is the first time that transplanted cells have successfully restored hearing in animals. The equivalent improvement in humans would be a shift from being unable to hear traffic to hearing a conversation.
"We believe this is an important step forward," said Dr Rivolta. "We now have a method to produce human cochlear sensory cells that we could use to develop new drugs and treatments, and to study the function of genes. And more importantly, we have proof of the concept that human stem cells could be used to repair the damaged ear. These results should stimulate further research into the development of a cell-based therapy for deafness."
The research was funded by the Medical Research Council (MRC) and the UK hearing research charities, Deafness Research UK and Action on Hearing Loss. Dr Paul Colville- Nash, Programme Manager for stem cell, developmental biology and regenerative medicine at the MRC, added, "This study clearly demonstrates that investment in UK stem cell research and regenerative medicine is beginning to bear fruit, and that is very exciting."