title: Clot retraction affects the extent of ultrasound-enhanced thrombolysis in an ex vivo porcine thrombosis model.
abstract: We investigated ultrasound-enhanced thrombolysis in two whole-blood clot models using a Food and Drug Administration-approved contrast agent (Definity, Lantheus Medical Imaging; Billerica, MA USA) and thrombolytic drug (recombinant tissue-type plasminogen activator [rt-PA]) (Genentech; South San Francisco, CA USA). Porcine venous blood was collected from donor hogs and coagulated in vials made of two different materials. This method produced clots with differing compositional properties, as determined by routine scanning electron microscopy and histology. Clots were deployed in an ex vivo porcine thrombosis model, and exposed to an intermittent ultrasound scheme previously developed to maximize stable cavitation while acoustic emissions were detected. Exposure to 3.15 μg/mL rt-PA promoted lysis in both clot models, compared with exposure to plasma alone. However, only unretracted clots experienced significant enhancement of thrombolysis in the presence of rt-PA, Definity, and ultrasound, compared with treatment with rt-PA. In these clots, microscopy revealed loose erythrocyte aggregates, a significantly less extensive fibrin network and a higher porosity, which may facilitate increased penetration of thrombolytics by cavitation.
authors: University of Cincinnati, Biomedical Engineering Program, College of Engineering and Applied Science, Cincinnati, OH 45267, USA. suttonjt@mail.uc.edu
authors: Jonathan T
authors: JT
authors: Sutton
authors: Nikolas M
authors: NM
authors: Ivancevich
authors: Stephen R
authors: SR
authors: Perrin
authors: Deborah C
authors: DC
authors: Vela
authors: Christy K
authors: CK
authors: Holland
mesh_terms: D000818:Animals; D001777:Blood Coagulation / Q000528:radiation effects*; D003131:Combined Modality Therapy / Q000379:methods; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D019220:High-Energy Shock Waves; D066298:In Vitro Techniques; D013552:Swine; D015912:Thrombolytic Therapy / Q000379:methods*; D013927:Thrombosis / Q000503:physiopathology* / Q000628:therapy*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator