The regenerative power of birds - could it work for hearing loss in humans?
In collaboration with scientists from around the world, including Dr Jennifer Stone (Seattle USA), Dr Daudet has shown that Notch plays a significant role by controlling the number of hair cells that are regenerated in the damaged chick ear. Signalling by Notch from one cell to another stops cells becoming hair cells and thus prevents too many forming. This is important, because in order for the regenerated hair cells to work properly, they must be present in an ordered pattern within the cochlea. We understand how the right number of cells is regenerated; however the nature of the signals triggering the regenerative response in the avian inner ear remains mysterious. Answering this question is one of the major objectives of Dr Daudet’s current research.Vivienne Michael, Chief Executive of Deafness Research UK, said: “This groundbreaking research is essential for those with hearing problems. Looking into the hearing of birds is truly cutting-edge research and Dr Daudet’s work gives us real hope of a future regenerative cure for people with hearing impairments everywhere.”There are many challenges still to overcome and even when the secrets of avian hearing have been unearthed, there will still be some way to go before the findings can be of benefit to humans, but raising the prospect of human hair cell regeneration offers one of the best hopes for a cure for long term deafness. Until then, Dr Daudet and his team continue to crack open the mysteries of the cochlea and inner ear regeneration.
Dr Daudet’s laboratory is investigating development and regeneration in the chick inner ear and, in particular, studying the function of a protein called Notch in the formation of hair cells. Notch is an important signalling protein that mediates communication between cells and is present in both mammals and birds.
In humans, damage to the inner ear by factors such as loud noise and certain types of drugs can lead to permanent hearing damage, tinnitus and even profound deafness. This deterioration is usually due to loss of the sensory ‘hair’ cells contained in the inner ear. These are extremely susceptible to both sound and injury and once they die, humans cannot grow more; yet in birds, these dead cells in the inner ear can regenerate throughout a bird’s lifetime to restore its hearing.
Current research led by Dr Nico Daudet, the inaugural Deafness Research UK UCL-EI Research Fellow, is investigating some of the signals and processes thought to be important for regeneration in bird’s inner ears. This may help researchers in the future to develop therapies to induce regeneration by cells of the inner ear and thereby reverse some forms of hearing loss in humans.“In birds and cold-blooded vertebrates, hair cells spontaneously regenerate following tissue damage, but in mammals this ability has been lost. Why?” said Dr. Daudet. “Could we stimulate regeneration in the human ear to treat certain forms of deafness?” The human ear is one of the most sophisticated of all the organs of the body, so Dr Daudet’s area of research is very complex. The ultimate development of efficient and safe cures relies on a better understanding of the molecular signals involved in hair cell formation and regeneration, which is where this new research is focused.