More than 700,000 people in the United States have heart attacks every year. If someone is rushed to the hospital quickly enough, doctors have an array of medications – plus some surgical options – to dissolve clots, thin blood, and reduce strain on the heart, keeping the heart pumping and reducing further damage. A new study, however, suggests a treatment that could keep some of that damage from happening in the first place. Getting an injection of negatively charged "microparticles" within 24 hours of a heart attack, the study found, could protect the heart so that 50 percent as much muscle was damaged. 

The microparticles – derived from polystyrene, microdiamonds, or biodegradable poly(lactic-co-glycolic acid) – in the injection protect the heart by attaching themselves to inflammatory monocytes. These cells are heavy hitters in the body's immune system, traveling to sites of damage and infection and causing inflammation. Although this inflammation is a natural part of the immune response, in the case of a heart attack, it can often cause even more harm.

"In most heart attacks, the biggest problem is that over time your heart gets damaged and its capacity shrinks, so after heart attacks it takes a long time to recover," says Daniel Getts, an immunology researcher at Northwestern University. The treatment would not help in the most severe cases that prove quickly fatal. But it could improve lives after heart attacks for many other patients. The researchers also think the microparticles could help fight other diseases and conditions where the immune system's inflammatory response becomes harmful, including stroke and West Nile virus.