The life-threatening myocardial infraction is caused by the complete occlusion of coronary artery, leading to losses of downstream myocardium and the development of post-infarction heart failure. By seeding cardiac cells onto scaffolds and nurturing their growth in vitro, engineered tissues are expected to generate natural heart structures and functions, and be transplanted to restore infarcted hearts. In fact, the healthy natural myocardium possesses a hierarchically aligned structure with different layers, while the synchronous contractions are triggered by electrical impulses propagating along the cardiac conduction system. It is important but remains a challenge to consider both elongated and aligned morphologies and electrical signal propagation during cardiac tissue cultivation.
Here, super-aligned carbon nanotube sheets (SA-CNTs) are explored to culture cardiomyocytes, mimicking the aligned structure and electrical impulse transmission behavior of natural myocardium. The SA-CNTs not only induce an elongated and aligned cell morphology of cultured cardiomyocytes, but also provide efficient extracellular signal transmission pathways required for regular and synchronous cell contractions. Furthermore, the SA-CNTs can reduce the beat-to-beat and cell-to-cell dispersion in repolarization of cultured cells, which is essential for normal beating rhythm and potentially reduce the occurrence of arrhythmias. Finally, SA-CNTs based flexible one-piece electrodes demonstrate a multipoint pacing function. These excellent properties make SA-CNTs promising in applications in cardiac resynchronization therapy in patients with heart failure following myocardial infarctions.