Can nerve cells regenerate?

Deep inside the inner ear are tiny structures known as hair cells. The exposed part of these sensory cells are hair-like offshoots called cilia, which are surrounded by liquid within the balance organs of the inner ear and send a signal to the brain when they are swished about by the head changing positions. Without the cilia, a person's sense of balance is compromised.

Doctors long have known that streptomycin can destroy the hair cells and, for this reason, avoid prescribing the antibiotic when something less potent will work. Since streptomycin often is the most effective treatment of certain bacterial infections such as tuberculosis, seriously ill patients may have to accept permanent inner-ear damage as the lesser of two undesirable outcomes.

The destruction of hair cells always has been regarded as permanent because these sensory cells share many similarities with brain neurons, which are known not to regenerate. However, experiments suggest that the sensory cells in the ear's balance organs--known as the vestibular apparatus--may be able to regenerate themselves if conditions are right. Pedro Weisleder, University of Texas at Austin Department of Zoology, points out that promising new research could lead to drugs or treatment processes that would stimulate the vestibular apparatus to regenerate its sensory cells. This essentially could be a cure for certain balance difficulties or types of hearing loss and could lead to a better general understanding of cell regeneration in the human body.

"Up until four years ago, it was accepted that when these cells were destroyed, they could not be replaced. The rule is that the more specialized the organism is, by tendency, the more capacity for regeneration is lost. But [in 1988], a Danish researcher injected some parrots with a cell proliferation marker...