Study: Nanodroplets, Ultrasound ‘Drills’ Effectively Break Up Blood Clots

A new technique developed by engineering researchers has found that engineered nanodroplets and an ultrasound “drill” can effectively break up blood clots from the inside out. Although the technique has not undergone clinical testing, in vitro testing has shown promising results.

The new approach is designed to treat retracted blood clots, which form over extended periods of time and are especially dense, according to the investigators. These clots are difficult to treat because they are less porous than other clots, making it more challenging for drugs to penetrate the clot.

The new technique involves 2 components. The nanodroplets are tiny lipid spheres filled with low boiling-point perfluorocarbons (PFCs), meaning a small amount of ultrasound energy will cause the liquid to convert into gas. As this happens, the PFCs expand rapidly, vaporizing the nanodroplets and forming microscopic bubbles, according to the study.

“We introduce nanodroplets to the site of the clot, and because the nanodroplets are so small, they are able to penetrate and convert to microbubbles within the clots when they are exposed to ultrasound,” said first author Leela Goel, a PhD student in biomedical engineering, in a press release.

After the bubbles form within the clots, exposure of the clots to ultrasound oscillates the bubbles, causing them to behave like tiny jackhammers, disrupting the clot’s physical structure and helping dissolve the clots, according to the study. The vibration also creates larger holes in the clot mass that allow blood borne anti-clotting drugs to penetrate deep into the clot and continue breaking it down.

The ultrasound transducer enables this technique after being introduced to the blood vessel via a catheter. The drill can aim ultrasound directly ahead, which makes it extremely precise, according to the study authors. It is also able to direct enough energy to the targeted location in order to activate the nanodroplets without damaging surrounding healthy tissue. The drill utilizes a tube that allows users to inject nanodroplets at the site of the clot.

Investigators compared various combinations of drug treatments, the use of microbubbles and ultrasound, and the new technique with in vitro testing.

“We found that the use of nanodroplets, ultrasound, and drug treatment was the most effective, decreasing the size of the clot by 40%, plus or minus 9%,” said corresponding author Xiaoning Jiang, PhD, Dean F. Duncan Distinguished Professor of Mechanical and Aerospace Engineering at North Carolina State University, in a press release.

Xiaoning said using the nanodroplets and ultrasound alone reduced the mass by 30%, plus or minus 8%. In comparison, using drug treatment, microbubbles, and ultrasound reduced clot mass by only 17%, plus or minus 9%, and all these tests were conducted within the same 30-day treatment period.

“The early test results are very promising,” Xiaoning concluded.

REFERENCE

Nanodroplets and Ultrasound ‘Drills’ Prove Effective at Tackling Tough Blood Clots [news release]. NC State University News; January 7, 2021. https://news.ncsu.edu/2021/01/nanodroplet-ultrasound-drill-clots/. Accessed January 12, 2021.