Defined Engineered Human Myocardium With Advanced Maturation for Applications in Heart Failure Modeling and Repair.

Background: Advancing structural and functional maturation of stem cell-derived cardiomyocytes remains a key challenge for applications in disease modeling, drug screening, and heart repair. Here, we sought to advance cardiomyocyte maturation in engineered human myocardium (EHM) toward an adult phenotype under defined conditions.

Methods: We systematically investigated cell composition, matrix, and media conditions to generate EHM from embryonic and induced pluripotent stem cell-derived cardiomyocytes and fibroblasts with organotypic functionality under serum-free conditions.

Sensing Cardiac Electrical Activity With a Cardiac Myocyte--Targeted Optogenetic Voltage Indicator.

Rationale: Monitoring and controlling cardiac myocyte activity with optogenetic tools offer exciting possibilities for fundamental and translational cardiovascular research. Genetically encoded voltage indicators may be particularly attractive for minimal invasive and repeated assessments of cardiac excitation from the cellular to the whole heart level.

Objective: To test the hypothesis that cardiac myocyte-targeted voltage-sensitive fluorescence protein 2.

Optical mapping of ventricular arrhythmias in LQTS mice with SCN5A mutation N1325S.

Transgenic expression of SCN5A mutation N1325S creates a mouse model for type-3 long QT syndrome (LQT3), TG-NS/LQT3. Optical mapping is a high temporal and spatial resolution fluorescence mapping system that records 256 action potentials simultaneously in a Langendorff-perfused heart. Here for the first-time, we provide a spatial view of VT in a genetic LQT3 model using optical mapping.