Cardiovascular disease is responsible for a third of the deaths that occur in the United States each year, and atherosclerosis — the build-up of plaque on artery walls — is one of its leading causes.
But now scientists and engineers, as detailed in a recent issue of the Proceedings of the National Academy of Sciences, have come up with a nanoparticle that can target and attack plaque, in the hopes of finding a treatment for atherosclerosis.
"The purpose of our grant is to develop targeted nanoparticles that specifically detect atherosclerotic plaques," explained Erkki Ruoslahti, distinguished professor at the Burnham Institute for Medical Research at the University of California, Santa Barbara, in a press release announcing the findings. "We now have at least one peptide, described in the paper, that is capable of directing nanoparticles to the plaques."
The nanoparticles used were lipid-based molecule groupings that form a sphere, which is called a micelle. On the surface of the micelle is a piece of protein called a peptide, which binds to the exterior of plaques.
Another professor at UCSB, co-author Matthew Tirrell, dean of the College of Engineering, worked closely with Ruoslahti on the project because he specializes in lipid-based micelles, which "turned out to be a perfect fit with our targeting technology," said Ruoslahti. He added that UCSB's strength in several different research areas — from materials to chemistry to bioengineering — helped speed the project along.
In the study, mice kept on a special high-fat diet eventually developed atherosclerotic plaques, and researchers injected the micelles into these mice, allowing the nanoparticles to circulate for three hours. Plaques tend to rupture at points where their tissue meets normal tissue and where the capsule on the plaque is the thinnest, and the researchers succeeded in targeting these areas.
"One important element in what we did was to see if we could target not just plaques but the plaques that are most vulnerable to rupture," said Ruoslahti. "It did seem that we were indeed preferentially targeting those places in the plaques that are prone to rupture."
Tirrell added that he thinks the nanoparticles used in this project are the best candidates for therapy because they are versatile, flexible and can easily be self-assembled as they circulate through the body.
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