Postnatal Slc26a4 gene therapy improves hearing and structural integrity in a hereditary hearing loss model
Yi-Hsiu Tsai, Peng-Yu Wu, Yu-Chi Chuang, Chun-Ying Huang, Hiroki Takeda, Hiroshi Hibino, Chen-Chi Wu, Yen-Fu Cheng
Yi-Hsiu Tsai, Peng-Yu Wu, Yu-Chi Chuang, Chun-Ying Huang, Hiroki Takeda, Hiroshi Hibino, Chen-Chi Wu, Yen-Fu Cheng
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Research Article Genetics Otology

Postnatal Slc26a4 gene therapy improves hearing and structural integrity in a hereditary hearing loss model

Abstract

Mutations in SLC26A4 are the second most common cause of hereditary hearing loss (HL) in many Asian countries, leading to DFNB4, a condition characterized by progressive HL and inner ear malformations. While gene therapy holds great potential, its postnatal application has remained unexplored because of the lack of suitable animal models and the challenges of prenatal intervention. To our knowledge, this study represents the first preclinical investigation of postnatal gene therapy for DFNB4 using a clinically relevant Slc26a4-mutant mouse model that closely replicates human auditory phenotypes. Utilizing the synthetic AAV.Anc80L65 vector, we achieved robust SLC26A4 delivery to critical cochlear regions, including the endolymphatic sac and cochlear lateral wall. Comprehensive phenotypic analyses revealed a critical therapeutic window spanning the neonatal and juvenile stages, within which AAV.Anc80L65-mediated SLC26A4 delivery significantly improved hearing, as evidenced by lower auditory brainstem response thresholds. Moreover, the therapy preserved hair cells, reduced endolymphatic sac enlargement, partially restored the endocochlear potential, and mitigated inner ear structural degeneration. These therapeutic effects persisted into adulthood, highlighting the long-term efficacy of postnatal gene therapy. Together, these findings establish a critical therapeutic window for DFNB4 and demonstrate the feasibility of targeting the endolymphatic sac and cochlear lateral wall for effective intervention.

Authors

Yi-Hsiu Tsai, Peng-Yu Wu, Yu-Chi Chuang, Chun-Ying Huang, Hiroki Takeda, Hiroshi Hibino, Chen-Chi Wu, Yen-Fu Cheng

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Figure 6

Juvenile delivery of Anc80.hSLC26A4 reduces the size of the enlarged endolymphatic sac and improves cochlear structures in L236P-mutant mice.

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Juvenile delivery of Anc80.hSLC26A4 reduces the size of the enlarged end...
(A) Representative images of the endolymphatic sac of vehicle-injected and Anc80.hSLC26A4-treated L236P-mutant mice at P105. Scale bars: 1 mm. (B and C) Quantification of the endolymphatic sac area (B) and vestibular aqueduct width (C) at P60 and P105. Data are expressed as the mean ± SD. *P = 0.01 and **P = 0.002, by unpaired, 2-tailed t test. (D) Hair cell morphology in cochlear turns of vehicle-injected and Anc80.hSLC26A4-treated mice at P105. Red and blue channels represent phalloidin and DAPI, respectively. Scale bars: 100 μm. (E and F) Quantification of basal IHCs (E) and OHCs (F) at P60 and P105. Data are presented as the mean ± SD. *P = 0.02, by Kruskal-Wallis test. (G) Morphology of marginal cells in the basal turn stria vascularis. Phalloidin staining (red) was used to delineate cell boundaries and epithelial organization. White arrows indicate atrophic marginal cells. Scale bars: 50 μm. (H) Quantification of the surface area of marginal cells at P60 and P105. Data are expressed as the mean ± SD. *P = 0.02 and ***P = 0.01, by Kruskal-Wallis test with Dunn’s multiple-comparison test. (I) EP value for vehicle-treated mice (n = 6) and AAV-treated L236P mice (n = 13) at P60. Data are presented as the mean ± SD. Statistical significance was assessed by unpaired, 2-tailed t test.