AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
Characterization of A Novel Cardiac/Myotropic and Near Complete Liver De-Targeting AAV Capsid
By He C, zhang S
1. Introduction: Inherited cardiac and skeletal muscle diseases are systemic disorders affecting multiple muscle types throughout the body. Effective gene therapy requires the development of more precise muscle-targeted delivery systems and safer AAV vectors. However, the intrinsic hepatotropism of naturally occurring AAV serotypes poses a substantial risk of dose-limiting liver toxicity upon high-dose systemic administration for cardiac or skeletal muscle gene therapy. A major challenge in AAV engineering lies in overcoming the trade-off between safety and efficacy, as liver-detargeting mutations frequently compromise viral transduction efficiency. In this study, we utilize a human-genome displaying AAV library to screen muscle specific AAV and evaluate its tissue specificity after liver detargeting mutation. 2. Methods: Random human genomic sequences were inserted into the parental AAV9 capsid at positions 588/589 (VR VIII) and then packaged the capsid library into AAV screening library (size>4 million). Through two rounds of screening in human iPSC-derived myotubes and one round validation screening in mice, 8S09 capsid was identified for their significant muscle enrichment. To reduce liver tropism, a liver de-targeting mutation was introduced into AAV VR I of 8S09 to generate liver detargeting variant (LD)-8S09. Tissue specificity of LD-8S09 was examined in normal mice and non-human primate (NHP). 3. Results: In mice, S09 exhibited stronger transduction ability in both muscles and liver compared to AAV9. Interestingly, the VR I liver-detargeting mutation in 8S09 abolished hepatic tropism yet left muscle specificity entirely intact. Compared to AAV9, LD-8S09 demonstrated higher muscle transduction efficiency (15-24 х AAV9). Consistent with vector distribution, LD-8S09 revealed strong functional transduction in muscles at the RNA (30-265 х AAV9) and protein level (17-365 х AAV9) (Figure 1). In NHP, LD-8S09 showed strong functional transduction in heart (8.8 х AAV9) and skeletal muscles (4.9-17.6 х AAV9). At the DNA level, LD-8S09 exhibited near-complete hepatic detargeting (3% of AAV9), driving a marked increase in the heart-to-liver (17.1-fold) and skeletal muscle-to-liver (18.8-fold) ratios due to drastically reduced hepatic tropism (Figure 2). The therapeutic potential of LD-8S09-delivered base editor or normal MyBPc3 gene is being evaluated in DMD and HCM animal models. The results will be available in October 2026. 4. Conclusion: This high cardiac/muscle specificity combined with minimal hepatic uptake establishes LD-8S09 as a best-in-class vector for cardiac and skeletal muscle gene therapies.