Control of electromechanical waves in engineered tissue of human iPSC-cardiomyocytes using a Halbach array and magnetic nanoparticles

The Halbach array, originally developed for particle accelerators, is a compact arrangement of permanent magnets to create well-defined magnetic fields without heating. Here, we demonstrate its use for modulating the speed of electromechanical waves in cardiac syncytia of human stem cell-derived cardiomyocytes. At 40-50 mT magnetic field strength, a cylindrical dipolar Halbach array boosted the conduction velocity, CV, of excitation in a directional manner by up to 25% when the magnetic field was co-aligned with the electromechanical wave (but not when perpendicular to it). To observe the effects, a short-term incubation of the cardiac cell constructs with non-targeted magnetic nanoparticles, mNPs, was sufficient. This increased CV anisotropy, and the effects were most pronounced at slower pacing rates. Instantaneous formation and re-arrangement of elongated mNP clusters upon magnetic field rotation was seen, thus creating dynamic structural anisotropy that may have contributed to the directional CV effects. This approach may be useful for anti-arrhythmic control of cardiac waves. One sentence summary A Halbach array of permanent magnets can modulate the speed of excitation waves in human cardiac cell assemblies with magnetic nanoparticles.