After a heart attack has occurred, inflammatory cells known as monocytes rush to the damaged tissue. This causes the heart to swell, reducing its ability to pump blood, and further damaging the tissue – a potentially lethal situation. Now, however, scientists have discovered that injectable microparticles can help stop that from happening.

Developed in a collaboration between Illinois' Northwestern University and the University of Sydney in Australia, the 500-nanometer-wide particles are made from a biocompatible, biodegradable polymer called poly (lactic-co-glycolic) acid. The substance is already approved by the FDA, for use in absorbable sutures. It's also being looked at for use in the treatment of diabetes and breast cancer.

When injected into the bloodstream within 24 hours of a heart attack, the negatively-charged microparticles attract the positively-charged monocytes, as they're on their way to the heart. When one of the monocytes bonds to a particle, a signal within the cell is triggered, telling it that it's dying. This causes it to change course and head for the spleen, the organ that disposes of dead cells.

As a result, inflammation of the heart is minimized. In animal models, this caused a 50 percent reduction in the size of heart lesions.

Lab tests have indicated that the microparticles could be also used to treat a number of other inflammatory diseases, such as West Nile virus, colitis, inflammatory bowel disease, multiple sclerosis, and peritonitis.

The particles are now being commercially developed by biotech start-up Cour Pharmaceutical Development Company, with clinical trials on heart attack victims hoped to begin with two years. A paper on the research was published this week in the journal Science Translational Medicine.

Sources: Northwestern University, Cour Pharmaceutical Development Company