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Updated: Aug 9, 2025
Adeno-Associated Virus-Mediated Delivery of CRISPR for Cardiac Gene Editing in Mice
Published on: August 2, 2018
Efficient in vivo genome editing prevents hypertrophic cardiomyopathy in mice
Daniel Reichart1,2, Gregory A Newby3,4,5, Hiroko Wakimoto1
1Department of Genetics, Harvard Medical School, Boston, MA, USA.
Insights
Genetic therapies show promise for hypertrophic cardiomyopathy (HCM). Adenine base editors corrected pathogenic variants in mice, preventing disease. Cas9 nuclease also inactivated the variant, though with some toxicity.
Area of Science:
- Cardiovascular Genetics
- Molecular Cardiology
- Gene Therapy
Background:
- Dominant missense pathogenic variants in cardiac myosin heavy chain are the primary cause of hypertrophic cardiomyopathy (HCM).
- HCM is an incurable condition associated with increased risks of stroke, heart failure, and sudden cardiac death.
Purpose of the Study:
- To evaluate the efficacy of two genetic therapies, adenine base editor (ABE8e) and Cas9 nuclease, delivered via adeno-associated virus serotype 9 (AAV9), in a mouse model of HCM.
- To assess the potential of these therapies to prevent disease development by correcting or silencing the heterozygous HCM pathogenic variant (myosin R403Q).
Main Methods:
- Adenine base editor (ABE8e) and Cas9 nuclease were delivered using dual-AAV9 vectors in mice with the heterozygous myosin R403Q variant.
- Correction and inactivation of the pathogenic variant were assessed in cardiac tissues.
- Cardiac structure and function were evaluated to determine therapeutic outcomes.
Main Results:
- A single dose of dual-AAV9 vectors carrying RNA-guided ABE8e corrected the pathogenic variant in over 70% of ventricular cardiomyocytes, leading to durable, normal cardiac structure and function.
- Additional dosing of ABE8e increased editing in atria but also led to bystander editing.
- AAV9 delivery of RNA-guided Cas9 nuclease inactivated the pathogenic allele in a dose-dependent manner, but exhibited toxicities, indicating a narrow therapeutic window.
Conclusions:
- Preclinical studies demonstrate that single-dose genetic therapies hold significant potential for treating hypertrophic cardiomyopathy.
- Adenine base editing offers a promising approach for correcting pathogenic variants, while Cas9 nuclease provides an option for allele inactivation.
- These findings support the development of gene-based strategies to prevent HCM and its associated complications.
Abstract:
Dominant missense pathogenic variants in cardiac myosin heavy chain cause hypertrophic cardiomyopathy (HCM), a currently incurable disorder that increases risk for stroke, heart failure and sudden cardiac death. In this study, we assessed two different genetic therapies-an adenine base editor (ABE8e) and a potent Cas9 nuclease delivered by AAV9-to prevent disease in mice carrying the heterozygous HCM pathogenic variant myosin R403Q. One dose of dual-AAV9 vectors, each carrying one half of RNA-guided ABE8e, corrected the pathogenic variant in ≥70% of ventricular cardiomyocytes and maintained durable, normal cardiac structure and function. An additional dose provided more editing in the atria but also increased bystander editing. AAV9 delivery of RNA-guided Cas9 nuclease effectively inactivated the pathogenic allele, albeit with dose-dependent toxicities, necessitating a narrow therapeutic window to maintain health. These preclinical studies demonstrate considerable potential for single-dose genetic therapies to correct or silence pathogenic variants and prevent the development of HCM.
