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Small. 2017 Sep;13(36). doi: 10.1002/smll.201700954. Epub 2017 Jul 18.

Enhanced Fibrinolysis with Magnetically Powered Colloidal Microwheels.

Author information

1
Chemical and Biological Engineering Department, Colorado School of Mines, 1500 Illinois St., Golden, CO, 80401, USA.
2
Department of Anesthesiology, University of Colorado School of Medicine, 12800 East 19th Ave., Aurora, CO, 80045, USA.
3
Department of Pharmacology, University of Colorado School of Medicine, 12800 East 19th Ave., Aurora, CO, 80045, USA.
4
Department of Pediatrics, University of Colorado School of Medicine, 12800 East 19th Ave., Aurora, CO, 80045, USA.

Abstract

Thrombi that occlude blood vessels can be resolved with fibrinolytic agents that degrade fibrin, the polymer that forms between and around platelets to provide mechanical stability. Fibrinolysis rates however are often constrained by transport-limited delivery to and penetration of fibrinolytics into the thrombus. Here, these limitations are overcome with colloidal microwheel (µwheel) assemblies functionalized with the fibrinolytic tissue-type plasminogen activator (tPA) that assemble, rotate, translate, and eventually disassemble via applied magnetic fields. These microwheels lead to rapid fibrinolysis by delivering a high local concentration of tPA to induce surface lysis and, by taking advantage of corkscrew motion, mechanically penetrating into fibrin gels and platelet-rich thrombi to initiate bulk degradation. Fibrinolysis of plasma-derived fibrin gels by tPA-microwheels is fivefold faster than with 1 µg mL-1 tPA. µWheels following corkscrew trajectories can also penetrate through 100 µm sized platelet-rich thrombi formed in a microfluidic model of hemostasis in ≈5 min. This unique combination of surface and bulk dissolution mechanisms with mechanical action yields a targeted fibrinolysis strategy that could be significantly faster than approaches relying on diffusion alone, making it well-suited for occlusions in small or penetrating vessels not accessible to catheter-based removal.

KEYWORDS:

colloids; directed-assembly; fibrinolysis; propulsion; thrombosis

PMID:
28719063
DOI:
10.1002/smll.201700954

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