Tokyo, Japan -- 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
Related stories:
Newly identified role for 'power plants' in human cells could lead to targeted therapies
Scientists have determined that human cells are able to shift important gene products into their own mitochondria, considered the power plants of cells. The finding could eventually lead to therapies for dozens of diseases.
The APCs of nerve cell function
Rapid information processing in the nervous system requires synapses, specialized contact sites between nerve cells and their targets. One particular synapse type, cholinergic, uses the chemical transmitter acetylcholine to communicate between nerve cells. Cholinergic synapses are essential for normal learning and memory, arousal, attention, and all autonomic (involuntary) nervous system functions. Malfunction of cholinergic synapses is implicated in Alzheimer's disease, age-related hearing loss, autonomic neuropathies, and certain forms of epilepsy and schizophrenia. Despite the importance of cholinergic synapses for cognitive and autonomic functions, little is known about the mechanisms that direct their assembly during development.
Roadrunner supercomputer puts research at a new scale
Less than a week after Los Alamos National Laboratory's Roadrunner supercomputer began operating at world-record petaflop/s data-processing speeds, Los Alamos researchers are already using the computer to mimic extremely complex neurological processes.
Gene therapy involving antibiotics may help patients with Usher syndrome
A new approach to treating vision loss caused by Type 1 Usher syndrome (USH1), the most common condition affecting both sight and hearing, will be unveiled by a scientist at the annual conference of the European Society of Human Genetics today. Ms Annie Rebibo Sabbah, from the Genetics Department of the Rappaport Faculty of Medicine, Technion, Haifa, Israel, will tell the conference that preliminary results using a class of drugs called aminoglycosides, commonly used as antibiotics, had had promising effects in vitro and in cell culture.
St. Jude finds 'dancing' hair cells are key to humans' acute hearing
St. Jude Children's Research Hospital investigators have found that an electrically powered amplification mechanism in the cochlea of the ear is critical to the acute hearing of humans and other mammals. The findings will enable better understanding of how hearing loss can result from malfunction of this amplification machinery due to genetic mutation or overdose of drugs such as aspirin.
Zebrafish may help solve ringing in vets' ears
Ernest Moore, an audiologist and cell biologist at Northwestern University, developed tinnitus -- a chronic ringing and whooshing sound in his ears -- twenty years ago after serving in the U.S. Army reserves medical corps. His hearing was damaged by the crack of too many M16 rifles and artillery explosions. He suspects his hearing also suffered from hunting opossum with rifles as a kid on his grandmother's farm in Tennessee.
Looking at neurons from all sides
A new technique that marries a fast-moving laser beam with a special microscope that look at tissues in different optical planes will enable scientists to get a three-dimensional view of neurons or nerve cells as they interact, said Baylor College of Medicine scientists in a report that appears today in the journal
Nature Neuroscience.
Yeast gives rise to new concept: cell fuel is 'brains' behind division
With the cost of diesel and gasoline getting nearer to the hourly minimum wage, too bad the fuel doesn’t do more work - like deciding what route to take and pressing the gas pedal.