When inner ear stem cell therapy becomes a reality.

Editorial The clinical treatment of hearing loss is at once sophisticated and crude. Surgeons can use microsurgical techniques and lasers to manipulate ossicular prostheses fractions of a millimeter with often astounding improvement in hearing, for example, in the case of stapes fixation due to otosclerosis. For profound sensorineural impairment, the cochlea may be surgically implanted with an electrode that stimulates the spiral ganglion neurons of the cochlea, thereby enabling effective hearing for many people. Yet despite modern surgical techniques and scientific advances, outcomes for restoration of conductive hearing when there is no ossicular chain at all remain unpredictable at best. Cochlear implants are threaded into the cochlea with very little precision as to which neurons are stimulated by which electrodes. In addition , not a single surgical intervention will help the typical patient with tinnitus, for whom even sectioning of the auditory nerve would not provide relief. Scalpels and drills can only do so much. Roughly, the same situation exists for current hearing aid technology. The historical evolution of assistive hearing devices, from the lowly ear trumpet to the modern digital hearing aid, provides irrefutable evidence of progress. For many patients, a simple hearing aid properly fitted can be life changing. However, as the severity of hearing loss worsens, hearing aid limitations become increasingly clear—for the patient with poor discrimination, for example, even the most powerful amplification available provides a fundamentally impoverished version of the auditory world. In other words, conventional amplification can be both remarkably helpful and glaringly insufficient. The more demanding a patient's auditory needs are, the clearer the limitations in our methods of intervention often appear. It is quite plausible that molecular biology, rather than surgery or amplification, holds the key for the next transfor-mative leap forward in our ability to treat hearing loss. As the review article (" Stem Cell Therapy for the Inner Ear: Recent Advances and Future Directions ") in this issue by Okano and Kelley suggests, a great deal of research has been done in the field of stem cells for the inner ear. This field has progressed in a relatively short span of time from an intriguing area of hypothetical inquiry to a viable possibility in the not-too-distant horizon. Scientists are truly starting to unravel the mysteries of hair cells and what it would take to regenerate them in humans. Through the development of stem cell therapy for the inner ear, it …