Dante Disharoon1, Brian G Trewyn2, Paco S Herson3, David W M Marr1, Keith B Neeves4. 1. Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, USA. 2. Department of Chemistry, Colorado School of Mines, Golden, Colorado, USA. 3. Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA. 4. Departments of Bioengineering and Pediatrics, Hemophilia and Thrombosis Center, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA.
Abstract
BACKGROUND: To reestablish blood flow in vessels occluded by clots, tissue plasminogen activator (tPA) can be used; however, its efficacy is limited by transport to and into a clot and by the depletion of its substrate, plasminogen. OBJECTIVES: To overcome these rate limitations, a platform was designed to co-deliver tPA and plasminogen based on microwheels (µwheels), wheel-like assemblies of superparamagnetic colloidal beads that roll along surfaces at high speeds. METHODS: The biochemical speed limit was determined by measuring fibrinolysis of plasma clots at varying concentrations of tPA (10-800 nM) and plasminogen (1-6 µM). Biotinylated magnetic mesoporous silica nanoparticles were synthesized and bound to streptavidin-coated superparamagnetic beads to make studded beads. Studded beads were loaded with plasminogen and tPA was immobilized on their surface. Plasminogen release and tPA activity were measured on the studded beads. Studded beads were assembled into µwheels with rotating magnetic fields and fibrinolysis of plasma clots was measured in a microfluidic device. RESULTS: The biochemical speed limit for plasma clots was ~15 µm/min. Plasminogen-loaded, tPA-immobilized µwheels lyse plasma clots at rates comparableto the biochemical speed limit. With the addition of a corkscrew motion, µwheels penetrate clots, thereby exceeding the biochemical speed limit (~20 µm/min) and achieving lysis rates 40-fold higher than 50 nM tPA. CONCLUSIONS: Co-delivery of an immobilized enzyme and its substrate via a microbot capable of mechanical work has the potential to target and rapidly lyse clots that are inaccessible by mechanical thrombectomy devices or recalcitrant to systemic tPA delivery.
BACKGROUND: To reestablish blood flow in vessels occluded by clots, tissue plasminogen activator (tPA) can be used; however, its efficacy is limited by transport to and into a clot and by the depletion of its substrate, plasminogen. OBJECTIVES: To overcome these rate limitations, a platform was designed to co-deliver tPA and plasminogen based on microwheels (µwheels), wheel-like assemblies of superparamagnetic colloidal beads that roll along surfaces at high speeds. METHODS: The biochemical speed limit was determined by measuring fibrinolysis of plasma clots at varying concentrations of tPA (10-800 nM) and plasminogen (1-6 µM). Biotinylated magnetic mesoporous silica nanoparticles were synthesized and bound to streptavidin-coated superparamagnetic beads to make studded beads. Studded beads were loaded with plasminogen and tPA was immobilized on their surface. Plasminogen release and tPA activity were measured on the studded beads. Studded beads were assembled into µwheels with rotating magnetic fields and fibrinolysis of plasma clots was measured in a microfluidic device. RESULTS: The biochemical speed limit for plasma clots was ~15 µm/min. Plasminogen-loaded, tPA-immobilized µwheels lyse plasma clots at rates comparableto the biochemical speed limit. With the addition of a corkscrew motion, µwheels penetrate clots, thereby exceeding the biochemical speed limit (~20 µm/min) and achieving lysis rates 40-fold higher than 50 nM tPA. CONCLUSIONS: Co-delivery of an immobilized enzyme and its substrate via a microbot capable of mechanical work has the potential to target and rapidly lyse clots that are inaccessible by mechanical thrombectomy devices or recalcitrant to systemic tPA delivery.
Authors: Tonguc O Tasci; Dante Disharoon; Rogier M Schoeman; Kuldeepsinh Rana; Paco S Herson; David W M Marr; Keith B Neeves Journal: Small Date: 2017-07-18 Impact factor: 13.281
Authors: Gauri V Deodhar; Marisa L Adams; Sutapa Joardar; Madhura Joglekar; Malcolm Davidson; William C Smith; Madelyn Mettler; Sydney A Toler; Fiona K Davies; S Kim R Williams; Brian G Trewyn Journal: Langmuir Date: 2017-12-28 Impact factor: 3.882
Authors: Raphael M Byrne; Ashraf G Taha; Efthymios Avgerinos; Luke K Marone; Michel S Makaroun; Rabih A Chaer Journal: J Vasc Surg Date: 2013-12-17 Impact factor: 4.268
Authors: Bruce C V Campbell; Peter J Mitchell; Leonid Churilov; Nawaf Yassi; Timothy J Kleinig; Richard J Dowling; Bernard Yan; Steven J Bush; Helen M Dewey; Vincent Thijs; Rebecca Scroop; Marion Simpson; Mark Brooks; Hamed Asadi; Teddy Y Wu; Darshan G Shah; Tissa Wijeratne; Timothy Ang; Ferdinand Miteff; Christopher R Levi; Edrich Rodrigues; Henry Zhao; Patrick Salvaris; Carlos Garcia-Esperon; Peter Bailey; Henry Rice; Laetitia de Villiers; Helen Brown; Kendal Redmond; David Leggett; John N Fink; Wayne Collecutt; Andrew A Wong; Claire Muller; Alan Coulthard; Ken Mitchell; John Clouston; Kate Mahady; Deborah Field; Henry Ma; Thanh G Phan; Winston Chong; Ronil V Chandra; Lee-Anne Slater; Martin Krause; Timothy J Harrington; Kenneth C Faulder; Brendan S Steinfort; Christopher F Bladin; Gagan Sharma; Patricia M Desmond; Mark W Parsons; Geoffrey A Donnan; Stephen M Davis Journal: N Engl J Med Date: 2018-04-26 Impact factor: 91.245