February 16, 2011

Hearing With Your Nose

(Ivanhoe Newswire) "“ Can you hear me now?  How about now?  You're probably familiar with those commercials, however, its not just phone companies who can help you hear better these days . . .  its stem cell scientists.  Researchers in Australia recently discovered that patients suffering from hearing problems beginning during infancy and childhood could benefit from a transplant of stem cells from their nose.  So if you still can't hear and want to, it might be time for you to get a little nosey.

Sensorineural hearing loss is a type of hearing loss in which the root cause lies in the vestibulocochlear nerve (Cranial nerve VIII), the inner ear, or central processing centers of the brain.  It is caused by the loss of sensory cells or neurons in the cochlea, the sensory organ of the inner ear responsible for hearing.  Most sensory hearing loss is due to poor hair cell function.  The hair cells may be abnormal at birth, or damaged during the lifetime of an individual.  There are both external causes of damage, like noise trauma and infection, and intrinsic abnormalities, like deafness genes. The condition can have genetic causes, often arising during infancy and childhood, hindering cognitive development and leading to speech and language problems.

"One of the challenges in tackling this condition is that the regenerative ability of the human cochlea is severely limited," which lead author Dr. Sharon Oleskevich from the Hearing Research Group at The University of New South Wales was quoted as saying.  "It has been proposed that the transplantation of cells from other parts of the body could treat, prevent or even reverse hearing loss.  The transplanted cells have the potential to repair tissue by replacing damaged cells and enhancing the survival of existing cells, preventing the condition from developing further."

Nasal stem cells were injected into the cochlea of mice displaying symptoms of hearing loss in an effort to examine the effects of this treatment.  Mice were chosen for this treatment as they display a comparable decline in hearing function following infancy.

"The authors have used an interesting type of adult stem cell, related to mesenchymal stem cells, to reduce the extent of hearing loss," which Jan Nolta, Associate Editor of STEM CELLS, was quoted as saying.  "Since the cells did not integrate into the cochlea, it is likely that the effects from the adult stem cells were due to the release of factors to preserve function of the endogenous stem cells.  Mesenchymal stem cells are known to provide factors to keep many types of cells healthy and functioning."

Patient hearing levels were examined via auditory brainstem response assay, which ultimately determines the lowest sound level to which the brain responds, known as the hearing threshold.

The mice that received the transplanted cells were compared to mice that had not received the treatment a month later, revealing that the hearing threshold level in stem cell-transplanted mice was notably lower.

"The results demonstrate a significant effect of nasal stem cell transplantations for sensorineural hearing loss," concluded Oleskevich.  "These cells can be obtained easily from the nasal cavity making this transplantation a potential treatment for other human conditions including Parkinson's disease and cardiac infarction."

SOURCE: STEM CELLS, February 15, 2011