Researchers have shown that bone marrow stem cells injected into a damaged inner ear can speed hearing recovery after partial hearing loss. The related report by Kamiya et al, “Mesenchymal stem cell transplantation accelerates hearing recovery through the repair of injured cochlear fibrocytes,” appears in the July issue of The American Journal of Pathology.
Hearing loss has many causes, including genetics, aging, and infection, and may be complete or partial. Such loss may involve damage to inner ear cells called cochlear fibrocytes, which are fundamental to inner ear function. Some natural regeneration of these cells can occur after acute damage, leading to partial recovery of temporary hearing loss. But could such restoration be enhanced by using bone marrow stem cells, which can differentiate into various tissue-specific cell types”
Dr. Tatsuo Matsunaga of National Tokyo Medical Center pursued this hypothesis by utilizing a well-characterized rat model of drug-induced hearing loss. This model specifically destroys cochlear fibrocytes and leads to acute hearing loss. Although partial recovery occurs over many weeks, high-frequency hearing remains extremely diminished. Using this system, the investigators examined whether direct administration of stem cells into the inner ear could restore the cochlear fibrocyte population and aid hearing recovery.
Stem cells injected into the inner ear survived in half of the injured rats, where they migrated away from the site of injection toward the injured region within the inner ear. These stem cells divided in the new environment and expressed several proteins necessary for hearing, suggesting tissue-specific differentiation. Further, transplanted cells that migrated to the damaged area of the inner ear displayed shape similar to that of cochlear fibrocytes.
Importantly, transplanted rats exhibited faster recovery from hearing loss, particularly in the high frequency range, which is difficult to restore by natural regeneration. Stem cell migration into the damaged area of the inner ear improved hearing of high frequency sound (40 kHz) by 23% compared to natural recovery in untreated animals.
This is the first report to demonstrate hearing recovery following stem cell transplantation into the inner ear. “Cell therapy targeting regeneration of the cochlear fibrocytes may therefore be a powerful strategy to cure sensorineural hearing loss that cannot be reversed by current therapies,” state Dr. Matsunaga and colleagues.
Source: American Journal of Pathology
Biosingularity 
I have a question on this subject of using adult stem cells to regenerate tissue.
Would an increased blood level of CD34 stem cells accomplish similar effects over a longer period of time? In other words, if there is normal circulation in the effected area, and one could use a natural method to increase the blood level of one’s own bone marrow stem cells about 30% on a continuous basis could it be possible that the increased stem cell circulation could find it’s way to the effected area and could those stem cells differentiate to become the cochlear fibrocytes necessary to improve the hearing. Another related question is this; Were the stem cells used in the experiment modified in any way or is it a natural process of stem cells to become the cells of other tissues in the body, and if one could use natural means to increase the level of those cells in the blood would that not accomplish the same thing over time?
Are you doing the stem cells treatment for human beings now? If yes, please furnish details?
Please give me an answer! I suffer from hearing loss in the right ear after the surgery so I am very interested in this possibility! Is it done on the human beings? Is it dangerous?