Nanoparticle discovery aids detection of blood clots

| Contributing Reporter

For millions of people who suffer chest pain, a new discovery may accelerate testing for blocked arteries that can cause fatal heart attacks.

A new nanoparticle invented by researchers at the Washington University School of Medicine can find blood clots and make them visible on a new type of CT scanner.

The invention is an important step toward detecting blood clots faster and more accurately before they can contribute to heart attacks.

According to Assistant Professor of Medicine Dipanjan Pan, the nanoparticles latch onto a protein in blood clots called fibrin. This allows a spectral CT scan to quickly and accurately differentiate the clots from calcium deposits by color.

The technology cannot yet be used on humans, but early testing of these nanoparticles shows that it can distinguish blood clots from calcium in rabbits and other small animals.

Spectral CT, as its name suggests, is a new type of X-ray technology that shows multicolor images and discriminates between tissues injected with different metals, or contrast agents.

Traditionally, doctors use several tests to confirm whether a patient suffers from coronary artery disease. According to Pan, tests such as the cardiac stress test can put dangerous strain on patients.

Other tests include a black-and-white CT scan, but these images cannot differentiate between calcium deposits and a fatal blood clot, making it difficult for doctors to accurately diagnose patients.

Washington University currently has one of two spectral CT scanners in the world. The other scanner is at Philips Research in Hamburg, Germany.

The nanoparticle, co-invented by Pan and Professor of Medicine Gregory Lanza, contains millions of heavy metal bismuth atoms so that the particle can be visible to the scanner.

“But bismuth is toxic and that is a challenge that we had,” Pan said. “We had to come up with some way to encapsulate bismuth.”

The nanoparticles containing bismuth are coated with lipids so that they do not feel foreign to the body. Mixed with other compounds that create what Pan calls a “salad dressing” textured fluid, these nanoparticles seek out and attach themselves to fibrin when injected into the bloodstream.

The bismuth nanoparticles dissolve and break down after binding to clots.

According to Associate Professor of Medicine Shelton Caruthers, spectral CT is still a new technology that has been developing in concert with these nanoparticle contrast agents. Therefore, it will still be some years before this technique can be used in clinics around the world.

In the meantime, researchers at the University will continue to work for earlier detection of heart attacks.

Students are excited about the new development.

“I think it’s a great breakthrough. We’ll be able to recognize these dangers in a very noninvasive way before it actually becomes a problem,” said senior Keita Uchida, a pre-medical student interested in cardiology research. “Having this kind of technology nearby and having access to the medical school here will help students get that kind of exposure if they [want] to.”

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