Australian scientists may have accidentally stumbled upon a new method to reduce damage to the heart after a heart attack.

This unexpected discovery was made while researchers from the University of Sydney were using poly (lactic-co-glycolic) acid microparticles, made from the same material as dissolvable stitches, were working on something else. They were using the microparticles to track an immune cell called an inflammatory monocyte, which cleans up dead or dying cells in the site of inflammation, but also release enzymes and chemicals that kill living cells.

When the microparticles were injected into the specimen and then ingested by the monocytes, the monocytes were reported to change and they failed to turn up at the site of the inflammation. Instead, they were captured by the spleen, which cleanses the bloodstream.

"What we seem to have discovered is that by using this natural pathway we actually prevent these cells from going into the focus of inflammation and that reduces the inflammation fantastically," said co-author Professor Nicholas King, professor of immunopathology and head of the Department of Pathology at the University of Sydney. "It doesn't catch them all, but it catches most."

After a heart attack, most of the damage to the heart muscle is due to the inflammatory cells rushing to the scene of the tissue that is lacking in oxygen.

Researchers tested this new method to a mouse model of a heart attack. They injected microparticles into the bloodstream within 24 hours of the heart attack, and found that the heart lesion was reduced by half, and the heart was able to pump more blood.

"We can reduce the scarring by up to 50 per cent, which is quite substantial, and it increases the functional output of the heart by something like 30 per cent," King said. "If you reduced the amount of damage to the heart muscle, then you could in fact save them."

However, King explained that this new method only limits tissue damage caused after a heart attack, and cannot repair tissue already damaged during the heart attack. The new method also has no effect on the disease the triggers the heart attack. Nevertheless, he believes this new method will, "improve the heart function substantially and the patient will end up with a better quality of life."

The study was published in the journal Science Translational Medicine.