Researchers at Michigan State University have developed a system that allows the imaging and identification of inflamed atherosclerotic plaques, which are considered at risk of rupture. Its system consists of administering carbon nanotubes that are preferably captured by macrophages and monocytes, which tend to accumulate in inflamed plaques. The researchers then illuminate the blood vessel of interest with light and the carbon nanotubes vibrate and produce a sound in response. This photoacoustic effect allows researchers to locate and visualize the plates.
Atherosclerotic plaque rupture forms the basis for strokes and heart attacks, but no technology is currently available to definitively identify plaques at risk of rupture. “Currently, there is no effective way to accurately locate and treat vulnerable plaques before they cause a heart attack or stroke,” said Eliver Ghosn, a researcher involved in the study. “We hope our studies help change that.”
A telltale sign of a plaque at risk of rupture is that it becomes inflamed and that the inflammation worsens and attracts a wide variety of white blood cells. It is these cells that this new technique seeks. The approach is to administer carbon nanotubes that these cells tend to take from their environment.
“The power of our new technique lies in its selectivity,” said Bryan Smith, another researcher involved in the study. “Undoubtedly, there are other methods to create plates, but what distinguishes this strategy is that it is cellular. We are specifically examining the cells (called macrophages and monocytes) that are primarily responsible for making a plaque vulnerable in the first place. If you look at a normal blood vessel versus a plaque vessel, there are many more macrophages and monocytes in what the plaque contains. And our method is really looking at monocytes and macrophages. Virtually no other cell type occupies nanoparticles. “
Researchers can probe a blood vessel of interest using light to see if any plaque has significant levels of carbon nanotubes in its environment. However, the tubes respond to light by emitting sound that can be detected by an ultrasonic transducer.
“We shine light on an artery where we have delivered certain types of particles that can absorb that light,” Smith said. “As a product of the release of that energy, they can literally call us back in ways we can detect and use to create 3D images.”
To date, researchers have tested the particles in mice and have been able to successfully identify inflamed plaques in their vascularity. Another option may be to charge the particles with medications that can help treat the plaques.
Study a Advanced functional materials: Ultra-selective carbon nanotubes for photoacoustics Image of swollen atherosclerotic plaques