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Device, drug could help clear brain clots in stroke patients

By
Stephen Feller
Creating blood flow in a blocked blood vessel allows nanotherapeutics armed with clot-busting drugs to clear blockages. Photo by adike/Shutterstock
Creating blood flow in a blocked blood vessel allows nanotherapeutics armed with clot-busting drugs to clear blockages. Photo by adike/Shutterstock

BOSTON, Oct. 28 (UPI) -- Using the combination of a stent and nanotherapeutic drug, scientists have devised a method of clearing clots in blood vessels while lowering the chance that part of the clot will break off and cause an issue somewhere else in the body.

Nanotherapeutic drugs have previously been less effective with clots because they require blood flow in order to operate, which a blocked blood vessel prevents.

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The most effective treatment for clearing blood clots is stent-retriever thrombectomy, which involves placing a tube through the blockage, passing a closed stent through it, and opening the stent in order to physically pull the clot out of the blood vessel.

The new method combines using a stent to open the blood vessel, however pairing the physical clearing of a blood vessel with a nanotherapeutic drug coated in a tissue plasminogen activator, or tPa, which dissolves clots. So, if part of a clot breaks off a vessel wall, the drug will continue to dissolve the clot as it travels through the bloodstream.

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"Even with the retriever thrombectomy procedure, not all clots can be removed with a successful outcome," said Dr. Matthew Gounis, an associate professor of radiology at the University of Massachusetts, in a press release. "Clot fragments can be dislodged, which can lead to microclots and tissue damage downstream in the brain circulatory system, and physical dragging of the stent through the vessel can potentially be damaging as well."

Working with animals that have blood vessel sizes similar to humans, researchers used a stent to create a narrow channel through the center of the blockage. Restoring blood flow creates force in the blood vessel, activating the nanotherapeutic to release and allow tPa to start dissolving the clot. Once the clot is dissolved, the stent is re-sheathed and removed.

"What's progressive about this approach is that the temporary opening of a tiny hole in the clot -- using a stent device that is already commonly used clinically -- results in a local rise in mechanical forces that activate the nanotherapeutic to deploy the clot-busting drug precisely where it can best do its job," said Dr. Donald Ingber, a professor of vascular biology at Boston Children's Hospital and Harvard Medical School.

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The study is published in the journal Stroke.

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