Recently, hearing of mice with a genetic form of deafness which is similar to a type found in people was restored by a team of international researchers. This brings new hope for people suffering from hearing loss. Will genetic therapy be a new way to heal deafness? A senior scientist of Creative Biolabs explains more about this work.

Why choose gene therapy to do research?

Hearing loss is the most common sensory impairment in humans, which, according to statistics, currently disables 466 million people in the world. And the incidence of genetic hearing loss in newborns reaches up to 1‰. Many cases show that hearing loss is actually related to genetic DNA mutations, and there are nearly 100 genes known to be related, such as GJB2, SLC26A4, 12SrRNA, etc. Mutations in hereditary hearing loss include single nucleotide substitution, base deletion and insertion. These mutations lead to missense and nonsense mutations in the deafness gene.

Thus, selective correction at gene level may serve as an innovative and effective treatment for genetic hearing loss.

How does gene therapy work to heal deafness of mice?

Most cases of genetic hearing loss are result from mutations in DNA. DFNB9 is one of them, which is caused by a mutation in the otoferlin (OTOF) gene. The OTOF gene produces a protein called otoferlin, a component of the sound-sensing hair cells, without which the brain can’t receive any sound information.

Before doing clinical research on humans, the researchers of the team used mice as a model of human DFNB9 deafness. Their method restores the normal function of the ear by using viruses and protein that can infect cells and integrate DNA into that of cells. In this study, the researches edited healthy copies of the OTOF gene into an adeno-associated virus (AAV), which is stable and efficient without causing a significant immune response. However, it is quite small and not able to match with huge human genes, so the researchers engineered two different AAV vectors, each containing half of the gene.

The inner ear has a unique advantage in structure for its being relatively easy to touch, but close and filled with liquid, which allows the drug injected into the cochlea to maintain a high concentration in the target organ. The researchers injected these engineered viruses into the cochlea of the DFNB9 model mice and the result showed that this restored communication between the ear and the brain.

What are the advantages and disadvantages of gene therapy?

Gene therapy can restore the normal hearing better because it’s essentially a method to repair the ear, not artificially simulating the ear. However, gene therapy for hearing loss still faces some challenges, for example, the exogenous genes may not be stably expressed in vivo for a long time, the product of exogenous genes may cause a serious immune response, etc.

At present, most of the research on genetic hearing loss remains in genetic screening, diagnosis and guidance. Further research is needed on the correction of gene mutations, which proves a promising future for gene therapy for genetic hearing loss. As a CRO specializing in gene therapy, Creative Biolabs has a team of experienced scientists and well-treated staff and has established dozens of world-leading platforms. Concentrating on providing a wide range of early development services, such as the gene therapy strategy design, hair cell regeneration, validation & function assessment in vitro and in vivo and other customized services, Creative Biolabs works with worldwide clients to find the best way to conquer genetic hearing loss.