A synthetic AAV vector enables safe and efficient gene transfer to the mammalian inner ear

Abstract

Efforts to develop gene therapies for hearing loss have been hampered by the lack of safe, efficient, and clinically relevant delivery modalities1, 2. Here we demonstrate the safety and efficiency of Anc80L65, a rationally designed synthetic vector3, for transgene delivery to the mouse cochlea. Cochlear explants incubated with Anc80L65 encoding eGFP demonstrated high level transduction of inner and outer hair cells (60–100%). Injection of Anc80L65 through the round window membrane resulted in highly efficient transduction of inner and outer hair cells, a substantial improvement over conventional adeno-associated virus (AAV) vectors. Anc80L65 round window injection was well tolerated, as indicated by sensory cell function, hearing and vestibular function, and immunologic parameters. The ability of Anc80L65 to target outer hair cells at high rates, a requirement for restoration of complex auditory function, may enable future gene therapies for hearing and balance disorders.

The Assembly-Activating Protein Promotes Stability and Interactions between AAV’s Viral Proteins to Nucleate Capsid Assembly

“…that drive evolution, which has led to the biodiversity of serotypes and naturally occurring variants the AAV field has sampled and studied extensively (Gao et al, 2005). Indeed, this structural variation correlates with phenotypic variation in aspects relevant to AAV’s use as a gene transfer vector; e.g., production yields (Vandenberghe et al, 2009), transduction efficiency (Gao et al, 2004; Thomas et al, 2004), and tissue and cell tropism (Foust et al, 2009; Landegger et al, 2017). Based on these observations, numerous efforts to further modulate AAV function by engineering its capsid are underway (Grimm and Zolotukhin, 2015; Kotterman and Schaffer, 2014; Vandenberghe et al, 2009).…”

Local gene therapy durably restores vestibular function in a mouse model of Usher syndrome type 1G

“…Various viral vectors containing GFP as a reporter gene have been shown to transduce inner ear hair cells (11)(12)(13)(14)(15), and several studies have investigated the use of gene therapy to restore hearing and balance in animal models, with different degrees of success. However, to date, partial hearing improvement was only obtained for mouse models without severe dysmorphogenesis of the inner ear hair cells (16)(17)(18)(19)(20)(21)(22). Here, we focused on the genetic form of USH1 caused by mutations of USH1G, encoding the submembrane scaffold protein sans (23,24).…”

Hearing in the mouse of Usher

“…In a remarkable series of experiments from a team led by Stankovic, Holt, and Vandenberghe, Landegger et al 3 now show that Anc80L65 encoding GFP (Anc80L65-GFP) transduces 90–100% of inner and outer hair cells in both explanted mouse cochlear cultures and in mouse cochlea in vivo after neonatal administration through the round window membrane (Fig. 1e,f).…”

“…In this issue, two companion studies report important progress in research on gene therapy for the inner ear. Landegger et al 3 first characterize a synthetic adeno-associated viral vector (AAV) that highly efficiently transduces auditory and vestibular sensory hair cells in the mouse inner ear in vitro and in vivo , and the human vestibular sensory epithelium in vitro . Pan et al 4 then apply this vector to rescue hearing and balance in a mouse model of a human deaf-blindness disease called Usher syndrome type 1c.…”