Cross-species comparison reveals that Hmga1 reduces H3K27me3 levels to promote cardiomyocyte proliferation and cardiac regeneration.

In contrast to adult mammalian hearts, the adult zebrafish heart efficiently replaces cardiomyocytes lost after injury. Here we reveal shared and species-specific injury response pathways and a correlation between Hmga1, an architectural non-histone protein, and regenerative capacity, as Hmga1 is required and sufficient to induce cardiomyocyte proliferation and required for heart regeneration. In addition, Hmga1 was shown to reactivate developmentally silenced genes, likely through modulation of H3K27me3 levels, poising them for a pro-regenerative gene program.

An hiPSC-CM approach for electrophysiological phenotyping of a patient-specific case of short-coupled TdP.

Introduction: A healthy young woman, age 26 without prior cardiac complications, experienced an out-of-hospital cardiac arrest caused by ventricular fibrillation (VF), which coincided with a fever. Comprehensive diagnostics including echo, CMR, exercise testing, and genetic sequencing, did not identify any potential cause. This led to the diagnosis of idiopathic VF and installment of an implantable cardioverter defibrillator, which six months later appropriately intervened another VF episode under conditions comparable to the first event.