drug-device combination
The novel drug-device combination developed by a team from the Wyss Institute at Harvard University and the New England Center for Stroke Research at University of Massachusetts works quickly to re-vascularize a vessel obstructed by a blood clot. In this schematic, the re-vascularization process is depicted from left to right. The intra-arterial stent is used to open a small channel in the blood clot, restoring enough blood flow to trigger the clot-busting nanotherapeutic which is activated by physical cues of fluid shear force.Wyss Institute at Harvard University/New England Center for Stroke Research at the University of Massachusetts

American scientists have discovered a novel way of treating critical blood clots in patients with stroke by developing a highly effective drug-device combination.

Researchers from Wyss Institute for Biologically Inspired Engineering at Harvard University and New England Centre for Stroke Research (NECSTR) under University of Massachusetts, teamed up to create the drug-device combination that can readily dissolve away adverse clots blocking blood vessels in the brain.

This method consists of an injectable clot-bursting nanotherapeutic, which targets blockages via an intra-arterial device that in return repairs normal blood flow to the blocked vessels.

The nanotherapeutic developed by Wyss Institute is made of a collection of biodegradable nanoparticles, covered by a clot-bursting drug known as "tissue plasminogen activator (tPA)" that copies the mechanism of blood platelets inside human bodies.

Narrowing of blood vessels rapidly increases the trim force of blood flow at that location for creating a physical signal that in return prompts platelets to stick to the vessel wall. Nanotherapeutics follows the same process and releases tPA-covered nanoparticles in the narrowed areas as a reaction to fluid trim force. Once these nanoparticles are released in the areas where blood vessels are blocked, they bind to the blood clot and dissolve them away.

The most ordinary and effective treatment for stroke is "stent-retriever thrombectomy" procedure. It consists of putting a small tube through the blocked vessel, passing a closed stent through it, and then unlocking the stent to physically take out the blood clot.

However, thrombectomy doesn't remove all blood clots. "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," Mathew J Gounis from NECSTR and one of the authors of the study, said.

According to the study, the new drug-device combination uses the stent not to pluck out the blood clot, but to create a narrow channel helping in the restoration of blood flow via an opening in the centre of the blockage(s). This results in creating trim force fluid flow, triggering the nanotherapeutic to release and aim the clot-bursting drug. Once the blood clot is dissolved, the stent is re-sheathed and safely taken out from the vessel.

The team has successfully established to the clinical world that the drug-device combination performs proficiently by dissolving clots, same as the size of the ones in humans.

"We hope that one day it (drug-device combination) will have a positive impact on patients suffering from a range of medical crises resulting for blood clot occlusions," Netanel Korin, the co-first author of the study, said.

The study will be published in the December issue of Stroke Journal.

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