COMING SOON: REVERSING HEARING LOSS
As we age, our chances of becoming hearing impaired increases. (Like every other malicious condition, it seems.) About a third of 65-year-olds have hearing loss, and this rises to half by age 75. This is caused by simple degeneration of inner ear structures over time. If you have hearing problems, help is available in the form of prosthetic devices such as hearing aids and cochlear implants. But now, there is hope of using stem cells to actually reverse hearing loss.
Besides getting older, another major cause of hearing impairment is loud noises—either with long-term exposure to blaring noises such as motorcycling or listening to loud music or from a short blast of noise such as a gunshot or fireworks that can permanently damage cells in your inner ear. Some medications and illnesses that result in high fever, such as meningitis, may also damage the cochlea.
Treatment
If you have hearing problems, help is available. Treatment depends on the cause and severity of your hearing loss: Here, from the Mayo Clinic article Hearing Loss Diagnosis & Treatment, are options:
- Removing wax blockage. Earwax blockage is a reversible cause of hearing loss. Your doctor may remove earwax using suction or a small tool with a loop on the end.
- Surgical procedures. Some types of hearing loss can be treated with surgery, including abnormalities of the eardrum or bones of hearing (ossicles). If you’ve had repeated infections with persistent fluid, your doctor may insert small tubes that help your ears drain.
Hearing aids. If your hearing loss is due to damage to your inner ear, a hearing aid can be helpful. An audiologist can discuss with you the potential benefits of a hearing aid and fit you with a device. Open fit aids are currently the most popular, due to fit and features offered. [These are not covered by original Medicare but may be with Advantage Plans.]- Cochlear implants. If you have more severe hearing loss and gain limited benefit from conventional hearing aids, then a cochlear implant may be an option. Unlike a hearing aid that amplifies sound and directs it into your ear canal, a cochlear implant bypasses damaged or nonworking parts of your inner ear and directly stimulates the hearing nerve. An audiologist, along with a medical doctor who specializes in disorders of the ears, nose and throat (ENT), can discuss the risks and benefits. [This costs between $30,000 and $50,000 but may be covered by Medicare.]
Bringing Back Hearing Loss
But now there’s hope of bringing back “irreversible hearing loss.” Here are excerpts from the Harvard Stem Cell Institute article Hearing Loss:
The cells that collect sound information from the environment and send it to the brain are called hair cells. We are born with about 11,000 hair cells in each ear, and they need to last. We experience the slow progression of hearing loss as these fragile cells die due to excessive noises, exposure to certain drugs, and aging. As hair cells die, nearby brain cells that once carried sound information to the audio processing part of the brain also expire.
Sound On
Harvard Stem Cell Institute (HSCI) investigators have made it their mission to develop new ways to prevent and treat hearing loss. Our researchers are quickly progressing in their goal to replace audio-assistive devices with biologically based therapies that treat the cause of the disease by protecting or replacing lost cells in the ear.
Regeneration of Hair Cells
HSCI scientists have discovered which stem cells can become hair cells as well as the molecules that bring about this change. Using this information, our researchers are developing techniques to grow hair cells in the laboratory and implant them into the ear.
Stem cells can also be used to screen for drugs that could stimulate the regeneration of hair cells. This method has already produced drugs capable of partially restoring hearing in deaf rats. The next steps are identifying the right mixture of drugs that will regenerate the largest number of hair cells and assessing ways that these drugs can be delivered to the ear. The success in rodent models will eventually lead to drug tests in human stem cells.
HSCI scientists have also learned how to coax stem cells into becoming brain cells. Experiments on stem cell-derived auditory neurons show that they will form new connections with damaged hair cells in a laboratory dish.
Excitingly, our investigators then found that when the stem cell-derived auditory neurons were transported into deaf animals, the neurons helped to re-establish broken connections and animal hearing was improved. Further research needs to be done to increase the effect of this procedure, as well as to develop other ways to make brain cells.
Using this method in the clinic could allow an individual patient to receive his or her own stem cell-derived auditory neurons, preventing rejection by the immune system. The final step before application to the human ear will be to determine the best surgical approaches for cell transplantation.
For many seniors, this can’t come soon enough!