Researchers in the UK have taken a huge step toward treating deafness after stem cells restored hearing in animals for the first time.
The same improvement in people would mean shifting from not being able to hear traffic to being able to hear a conversation; but human treatments are still a distant prospect.
In roughly one in 10 people with profound hearing loss, nerve cells that should pick up electrical signals that the brain understands as sound, are damaged. Researchers at the University of Sheffield aim to replace these nerve cells, called spiral ganglion neurons, with new ones.
In order to do so, they used embryonic stem cells, which have the ability to become any other type of cell in the human body. A chemical soup was then added to them, converting them similar to the nerve cells needed. Finally, they were carefully injected into the inner ears of 18 deaf gerbils.
45 percent of the gerbils’ hearing range was restored by the end of the study, over the course of 10 weeks. Dr. Marcelo Rivolta stated:
“It would mean going from being so deaf that you wouldn’t be able to hear a lorry or truck in the street to the point where you would be able to hear a conversation. It is not a complete cure, they will not be able to hear a whisper, but they would certainly be able to maintain a conversation in a room.”
Reuters notes that gerbils were selected because their hearing range is similar to that of humans. Cochlear implants can offer a partial solution to loss of hair cells, but there is currently no treatment for nerve loss, also known as auditory neuropathy.
Stem cells can initially address nerve damage resulting in hearing loss, but it can also be used in a wider range of patients, if it can be used along with implants.
Significant uncertainties remain with the use of embryonic stem cells, because of their ability to morph into any other cell type in the body. Because of this, they can cause tumors. While this was not seen in the 10-week-long study with gerbils, Rivolta said that a longer study would be necessary to see if the gerbils grew tumors as well.
Another danger of using stem cells is that these transplanted cells can be rejected by the recipient’s immune system. Despite the risks with using stem cells, Doctors hope to use them to treat a wide ranges of diseases in the future, including Parkinson’s, diabetes, and cancer. More localized approaches like their use to treat deafness are a promising first step.