A new paper from researchers at Tel Aviv University (TAU), Israel, outlines a treatment for deafness based on getting genetic material into the cells of the inner ear to replace the genetic defect and bring about normal functioning of cells. In experiments with mice possessing a mutation in the gene SYNE4, the subjects were rescued from deafness, the treated mice developing normal hearing, “with sensitivity almost identical to that of healthy mice who do not have the mutation," pointed out study collaborator Professor Jeffrey Holt (Boston Children's Hospital and Harvard Medical School).

And these scientists are now focusing on developing gene therapy for other mutations. ”The findings are most promising,” said Prof. Holt.

The study was led by Professor Karen Avraham of the Department of Human Molecular Genetics and Biochemistry at TAU's Sackler Faculty of Medicine and Sagol School of Neuroscience. The paper was published in EMBO Molecular Medicine on December 22, 2020.

"Children inheriting the defective gene from both parents are born with normal hearing, but they gradually lose their hearing during childhood. The mutation causes mislocalization of cell nuclei in the hair cells inside the cochlea of the inner ear, which serve as soundwave receptors and are essential for hearing. This defect leads to the degeneration and eventual death of hair cells," Prof. Avraham explained.

"We implemented an innovative gene therapy technology: we created a harmless synthetic virus and used it to deliver genetic material — a normal version of the gene that is defective in both the mouse model and the affected human families," says Shahar Taiber, one of Professor Avraham's students on the combined MD-PhD course. "We injected the virus into the inner ear of the mice, so that it entered the hair cells and released its genetic payload. By so doing, we repaired the defect in the hair cells and enabled them to mature and function normally."

Optimism about this kind of therapy, for which there is a growing body of literature, has been boosted globally. "This is an important study that shows that inner ear gene therapy can be effectively applied to a mouse model of SYNE4 deafness to rescue hearing," says Prof. Wade Chien, MD, from the NIDCD/NIH Inner Ear Gene Therapy Program and Johns Hopkins School of Medicine, who was not involved in the study. "The magnitude of hearing recovery is impressive.”

Source: Science Daily