A new study with deaf mice from Boston Children’s Hospital and Harvard Medical School has enabled the ability to hear sounds at a whisper level. This advancement within gene therapy leaves scientists hopeful that the study with the mice will provide treatments for human patients in the future.
Cause of Deafness in the Study
While mice are obviously different than people, the study focused on the genetic instructions the body receives in development to form tiny hairs in the ear. These hairs help detect and send information to the brain. When the inner ear has a lack of these tiny hairs, or the hairs are disorganized, it causes a disease known as Usher Syndrome. This disease has strong negative effects on both hearing and vision. The hearing loss is classified as sensorineural, which is triggered by irregularities in the inner ear.
The mice in the study had disorganized microscopic hairs in their inner ear, impairing their hearing. Scientists used a synthetic virus injected into the mice that recovered proteins and sensory cells. The drug, Anc80, was used for transporting the necessary gene to the cochlea of the mice’ ears. This type of gene therapy is hopeful to assist in the further study of human deafness.
Results of the Study
After introducing the synthetic drug into the mice’ system, the harmonin level in the mice began to become functional. Harmonin is the protein that affected by Usher Syndrome, deteriorating the hairs in the inner ear. With the synthetic dose, harmonin levels were able to create full-length hairs in the inner ears of these mice. They could then be able to hear sounds up to a 25-decibel level – a whisper.
The downside of this experiment, however, is that there seems to be a statute of limitations on when mice can receive the drug. Newborn mice are the best candidates to receive the drug to treat their Usher Syndrome and have the best results. But after 10 days, scientists learned that the drug is not effective.
Future Plans for Gene Therapy
Researchers will have to prove that the effects of this drug are long-lasting before they can begin any type of human trials. The adeno-associated drug Anc80, however, has previously been used in different forms of gene therapy as well. For now, you can wait for updates on this new breakthrough in gene therapy for the deaf, and read more about the study at Nature.com.