# Enhanced gene delivery for CNS and sensory disorders

> **NIH NIH R01** · MASSACHUSETTS GENERAL HOSPITAL · 2022 · $355,007

## Abstract

PROJECT SUMMARY/ABSTRACT. Gene therapy using adeno-associated virus (AAV) vectors has shown great promise in
human clinical trials for diseases such as blindness and hemophilia. However, gene therapy is in its early phases to
address inherited hearing loss (IHL). Sensory cells called “hair cells”, reside in the inner ear and mediate hearing and
balance, and represent a major target for gene therapy to correct IHL. AAV vectors are currently the most promising
vector for gene therapy to the inner ear, although gene delivery efficiency to hair cells is suboptimal. The major long-
term goal of this proposal is to develop an effective gene delivery platform for therapy of hearing and balance disorders.
We have developed a hybrid gene delivery vector comprised of AAV vectors associated with endogenous nanoparticles
called exosomes, which we have termed exo-AAV. Our recent manuscript using gene addition therapy with exo-AAV1
achieved unprecedented gene delivery to inner ear hair cells and partial rescue of hearing and balance in a mouse model
of deafness involving the tetraspan membrane protein of hair cell stereocilia (Tmhs) gene. The current proposal is aimed
at enhancing our gene delivery efficiency and translation towards clinically relevant large animal models. We have
recently discovered that an AAV9 variant, AAV9-PHP.B, robustly transduces hair cells after injection into neonatal mice
and non-human primates (NHP). Gene delivery to the inner ear of NHP by AAV has never be demonstrated before and
will be a crucial step towards clinical trials. We will test whether we can improve AAV9-PHP.B’s transduction efficiency
even further via its incorporation into exosomes (exo-AAV9-PHP.B). Our specific aims are (1) To improve gene delivery
to cochlear hair cells using AAV9-PHP.B and exo-AAV9-PHP.B; (2) Investigate mechanisms of enhanced exo-AAV
transduction of cells and AAV9-PHP.B transduction of hair cells; (3) To develop the exo-AAV platform to allow industrial
scale-up/manufacturing for clinical use. For aim 1, we have preliminary data showing that AAV9-PHP.B mediates
efficient gene delivery to hair cells of the cochlea in vivo in rodents and NHP. In Aim 1a we will directly compare exo-
AAV9-PHP.B and standard AAV9-PHP.B at several doses for delivery to hair cells in mice and in NHPs. In Aim 1b we test
the ability of exo-AAV9-PHP.B and AAV9-PHP.B encoding Tmhs to rescue hearing and balance dysfunction in the Tmhs
knockout mouse. In Aim 1 c we will compare exo-AAV9-PHP.B and AAV9-PHP.B at gene delivery to hair cells in NHPs. In
Aim 2, we will investigate mechanism of transduction of hair cells by exo-AAV using blockade of specific cellular
processes as well as AAV capsid mutants to discern specific contributions to gene transfer by the AAV capsid or exosome
components. In aim 3, we will use properties of the exosome membrane to allow anion-exchange column
chromatography, an industrial scalable approach, for the purification of exo-AAV. We are also collabo...

## Key facts

- **NIH application ID:** 10378015
- **Project number:** 5R01DC017117-04
- **Recipient organization:** MASSACHUSETTS GENERAL HOSPITAL
- **Principal Investigator:** Casey A Maguire
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $355,007
- **Award type:** 5
- **Project period:** 2019-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10378015

## Citation

> US National Institutes of Health, RePORTER application 10378015, Enhanced gene delivery for CNS and sensory disorders (5R01DC017117-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10378015. Licensed CC0.

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