UW researcher makes hearing loss breakthrough

Shawn Doherty  —  8/28/2008 4:56 pm

A team of scientists has figured out how to transfer special genes to regenerate damaged cells in the inner ear, a technique that researchers say could one day lead to the restoration of hearing for both children born deaf and the elderly who are hard-of-hearing.

UW otolaryngologist Samuel Gubbels, working with a team of scientists at Oregon Health and Science University and Stanford University, grew specialized cells crucial for hearing by transferring a gene responsible for the formation of those cells into the inner ear of mouse embryos. Once the mice were born, researchers were able to prove that not only had they grown these new cells, which scientists call hair cells, inside their ears, but that the cells worked.

"Other teams have grown hair cells before," Gubbels said. "What's truly significant about our work is that the extra hair cells were shown to be functional and they had a connection to the brain. They actually work."

The findings are reported in this week's edition of the journal Nature.

The most common cause of deafness and loss of hearing is a problem with the hair cells inside the inner ear. These hair cells are quite different than the hair cells on other parts of the human body. They are acutely responsive to vibrations caused by physical and acoustical energy, or sound.

"They are like transformers," Gubbels explained. "They can transform energy into electrical signals that get passed into a hearing nerve and into the brain."

Children born deaf most frequently are born without these hair cells. Adults can lose their hearing because of damage to the hair cells, due to what Gubbels calls "environmental insults," like loud noises or toxins, or because of a genetic predisposition to hearing loss as they grow older. Currently the only way to treat hearing loss is with hearing aids or cochlear implants.

Scientists dream of being able to restore hearing in a more natural way. Chickens and other birds, for example, can regenerate lost or damaged hearing. Mammals cannot. But the technique Gubbels and the other scientists discovered, Gubbels said, "will put us one big step closer to being able to regrow these hair cells and restoring natural hearing to people."

That technology could take another decade or two to develop, Gubbels said. The next step is to use the same technology used in isolating and transplanting the hair cell genes to embryonic mice on real mice with a genetic defect that mimics the genetic defects in humans with hearing loss. And once that experiment is successful, Gubbels said, it will be time to try the technology on humans.

"It's not something I can go to my clinic with and offer to patients right now. But our discovery is keeping things on pace," he said.

Shawn Doherty  —  8/28/2008 4:56 pm