If you're answering questions with "What did you say?" because you've had your iPod turned up too loud or been to lots of loud rock concerts, it may be due to the most frequent cause of hearing impairment, loss of hair cells in the inner ear. Two research groups may be on the track to helping you recover some of those lost cells. Researchers at Oregon Health & Sciences Center have published results in the journal Nature showing they can stimulate growth of new auditory hair cells in the inner ear of mice, by adding a gene to other cells in the ear.

Even more exciting, Italian scientists have shown actual repair of the cochlea, the auditory portion of the inner ear. Mice with hearing loss caused by noise or toxic chemicals were treated with human umbilical cord blood stem cells (a type of adult stem cell) and showed repair of the damage. The cochlea in non-transplanted mice remained seriously damaged. According to Dr. Roberto P. Revoltella, lead author of the study, "Our findings show dramatic repair of damage with surprisingly few human-derived cells having migrated to the cochlea." The research will be published in volume 17, issue 6 of the journal Cell Transplantation.

Eh? Adult stem cells continue to be the only stem cell providing real success.