Heart muscle cells grown from patient stem cellsknown as human induced pluripotent stem cellderived cardiomyocytes, or hiPSC-CMsare a promising way to repair hearts damaged by heart attacks and heart failure. But transplanted hiPSC-CMs often have trouble syncing to the rhythm of native heart cells, which can cause dangerous arrhythmias after transplantation. Subscribe to our newsletter for the latest sci-tech news updates.