Treatment of monogenic and digenic dominant genetic hearing loss by CRISPR-Cas9 ribonucleoprotein delivery in vivo.

Summary

Extends inner ear gene delivery from gene replacement (AAV) to allele-specific gene editing. Liposome-mediated in vivo delivery of CRISPR-Cas9 ribonucleoprotein complexes specifically disrupted the dominant Tmc1 Beethoven mutation while sparing the healthy allele, preserving outer hair cell survival and function and improving hearing. In a digenic model combining the Tmc1 Beethoven and Atp2b2 Oblivion mutations, dual-targeted Cas9/sgRNA delivery produced partial hearing recovery, showing the approach can scale beyond single-gene deafness.

Key findings

• Liposome-delivered CRISPR-Cas9 ribonucleoprotein selectively edited the dominant Tmc1 Beethoven mutant allele in vivo, sparing the wild-type allele.
• Editing preserved outer hair cell survival and function, improving hearing thresholds relative to untreated mutant mice.
• In a digenic mouse model carrying two independent dominant deafness mutations (Tmc1 Beethoven and Atp2b2 Oblivion), dual-targeted editing produced partial hearing recovery.
• Demonstrates protein (not viral) delivery of gene-editing machinery as a route to treating dominant genetic hearing loss.