How can damaged cardiac tissue following a heart attack best be treated with replacement muscle cells? A research team under the supervision of the University of Bonn reports an innovative method: Muscle replacement cells to take over the function of the damaged tissue are loaded with magnetic nanoparticles. These nanoparticle-loaded cells are then injected into the damaged heart muscle and held in place by a magnet, causing the cells to engraft better onto the existing tissue. Using a mouse model, the scientists show that this leads to a significant improvement in heart function. The results are published online in Biomaterials.