Regulation of sodium/calcium homeostasis by BacNav gene therapy rescues cardiac dysfunction in chronic heart failure.

Despite continued progress, therapies to augment contractile function and prevent arrhythmias in patients with heart failure remain limited. Here, we present a two-pronged gene therapy approach that simultaneously augments peak Na+ current and Ca2+ transient amplitude in cardiomyocytes (CMs) to alleviate heart failure pathogenesis. Using in vitro engineered neonatal rat heart tissues, ex vivo adult mouse CMs, and in silico rabbit CMs, we show that expression of prokaryotic Na+ channels (BacNav) dose-dependently enhances Ca2+ transients and contractility of CMs by modulating Na+/Ca2+ exchanger activity and increasing sarcoplasmic reticulum Ca2+ stores. In mice, adeno-associated virus 9 (AAV9)-mediated BacNav therapy rescues contractile deficit, prevents arrhythmias, and improves transcriptomic dysregulation in a pressure-overload induced model of chronic heart failure. We further establish the safety of long-term systemic delivery of AAV9-BacNav in mice. Collectively, these studies support the translational promise of BacNav gene delivery as an effective therapy for electrical and contractile dysfunction in heart failure.