Drug-coated stents – wire-mesh tubes used to prop open clogged arteries – are a boon for heart disease sufferers. But in time, the body uses up the drug coating, which prevents scar tissue from blocking the artery again. Researchers at Drexel University in Philadelphia, PA, have developed a replenishable stent. Zachary Forbes, a biomedical engineering doctoral student, plated stents with a weak magnetic alloy. He and fellow grad student Benjamin Yellen then embedded the scar-preventing drugs in biodegradable magnetic nanospheres. To administer the drugs, doctors would inject the nanospheres and switch on an external magnetic field, causing the stent to capture the nanospheres. The scheme would let doctors readminister drugs throughout a patient’s (hopefully long) life, adjusting dosages or changing medication. Forbes and Yellen have formed Magnetic BioSystems to commercialize the invention.