Drug-embedded particles bolster heart function

October 20th, 2008 - 1:49 pm ICT by IANS  


Washington, Oct 20 (IANS) Tiny polymer beads developed by scientists can slowly release anti-inflammatory drugs after heart attacks and break down into non-toxic components.When injected into rats’ hearts after a simulated heart attack, the drug-embedded “microparticles” reduced inflammation and scarring, researchers have found.

Injecting the particles could cut the area of scar tissue formed after the heart attack in half and boost the ability of the heart to pump blood by 10 percent weeks later.

Doctors believe that certain anti-inflammatory drugs, if delivered directly into the heart after an attack, could prevent permanent damage and reduce the probability of heart failure later in life.

Hence, getting drugs to the right place at the right time is more challenging than simply swallowing an aspirin, said co-author Michael Davis, assistant professor in biomedical engineering at Georgia Tech and Emory University.

“If you look at previous studies to see what it would take to get enough of these drugs into the heart, they did things like direct injections twice a day,” he informed. “And there are clear toxicity issues if the whole body is exposed to the drug.”

As an alternative, Davis and graduate student Jay Sy, co-author of the paper, turned to microscopic particles made of a material called polyketals, developed by researchers.

The microparticles break down over a few weeks in the body, releasing the experimental drug SB239063. This drug inhibits an enzyme, MAP kinase, which is important during the damaging inflammation that occurs after a heart attack.

Davis said the drug gradually leaches out of the polyketal particles - half is gone after a week of just sitting around in warm water. In addition, the microparticles are broken down by white blood cells called macrophages, according to an Emory University press release.

“These are actually cells we’re trying to reach with the drug, because they’re involved in the inflammatory response in the heart,” he says. “The macrophages can surround and eat the particles, or fuse together if the particles are too big.”

Davis said polyketals have an advantage over other biodegradable polymers, in that they break down into neutral, excretable compounds that aren’t themselves inflammatory.

The results were published online this week and scheduled for publication later in Nature Materials.

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