Novel Development of Gene Delivery for Inner Ear -Dual Vector Method-

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K16832
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 56050:Otorhinolaryngology-related
• Research Institution: Okayama University
• Principal Investigator: Omichi Ryotaro 岡山大学, 医歯薬学域, 助教 (20771299)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 遺伝子治療 / 感音難聴 / 遺伝性難聴 / 聴覚 / 内耳 / 有毛細胞

Outline of Final Research Achievements

Two types of adeno-associated virus (AAV), AAV2 and AAV9, were introduced into the inner ear of 4-week-old wild-type mice with mature cochleae using the round window membrane and cochleostomy (RWM+CF) method. No ototoxicity was observed in auditory brainstem response (ABR) tests two weeks after injection. Immunostaining and confocal laser microscopy evaluation showed that the transduction efficiency was 96.92% for inner hair cells (IHCs) and 65.59% for outer hair cells (OHCs), which were higher than those reported in previous studies.

The transduction efficiency of AAV9 was lower when AAV9 was used alone compared to when it was combined with another AAV9 or AAV2. Dual transduction with AAV2 resulted in high transduction efficiency in both IHCs and OHCs, similar to that of single transduction, suggesting its high potential for gene therapy for hearing loss.

Free Research Field

耳鼻咽喉科

Academic Significance and Societal Importance of the Research Achievements

先天性感音難聴は出生児500人に１人に認められ、そのうち50-60%は遺伝子変異が原因である。根治的治療の手段として遺伝子治療の基礎的・臨床的研究が必要である。難聴の遺伝子治療モデルの最大の課題は「塩基配列サイズが大きな遺伝子を高効率に導入する」ことである。当研究では病原性や細胞毒性が低いAAV2をベクターとして組みあわせて使うDual Vector法により、より大きな塩基配列サイズの遺伝子を有毛細胞に導入することを実現した。これは難聴の実臨床へむけた遺伝子治療モデルとして、難聴診療に大きな波及効果をもたらすと考えられる。