title: Activation, aggregation and adhesion of platelets exposed to high-intensity focused ultrasound.
abstract: Using platelet-rich plasma, we investigated the effect of 1.1-MHz continuous wave high-intensity focused ultrasound (HIFU) on platelet activation, aggregation and adhesion to a collagen-coated surface. Platelets were exposed for durations of 10-500 s at spatial average intensities of up to 4860 W/cm(2). To avoid heating effects, the average temperature in the HIFU tank was maintained at 33.8 +/- 4.0 degrees C during platelet experiments. Flow cytometry, laser aggregometry, environmental scanning electron microscopy and passive cavitation detection were used to observe and to quantify platelet activation, aggregation, adhesion to a collagen-coated surface and associated cavitation. It was determined that HIFU can activate platelets, stimulate them to aggregate and promote their adherence to a collagen-coated surface. In principle, HIFU can stimulate primary, or platelet-related, hemostasis. Cavitation was monitored by a passive cavitation detector during aggregation trials and was quantified to provide a relative measure of the amount of cavitation that occurred in each aggregation trial. Regression analysis shows a weak correlation (r(2) = 0.11) between aggregation and ultrasound intensity, but a substantial correlation (r(2) = 0.76) between aggregation and cavitation occurrence.
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 430th Street, Seattle, WA 98105, USA. poliachi@u.washington.edu
authors.forename: S L
authors.initials: SL
authors.lastname: Poliachik
authors.forename: W L
authors.initials: WL
authors.lastname: Chandler
authors.forename: P D
authors.initials: PD
authors.lastname: Mourad
authors.forename: R J
authors.initials: RJ
authors.lastname: Ollos
authors.forename: L A
authors.initials: LA
authors.lastname: Crum
mesh_terms: D005434:Flow Cytometry; D006801:Humans; D015539:Platelet Activation; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D013696:Temperature; D014463:Ultrasonography / Q000379:methods