title: Single-walled carbon nanotubes activate platelets and accelerate thrombus formation in the microcirculation.
abstract: OBJECTIVE
  Although ambient nanoparticles have been shown to exert prothrombotic effects, manufactured nanoparticles are in this aspect less well investigated. Thus, the aim of this study was to characterize the effects of diesel, titanium dioxide rutile, and single-walled carbon nanotube nanoparticles on (i) platelet activation in vitro and (ii) on macro- and microcirculatory thrombus formation in vivo.
  
  
  METHODS
  Platelet P-selectin expression was measured by flow cytometry after incubation of whole blood with diesel (0.1mg/mL), titanium dioxide (0.1mg/mL) or single-walled nanotubes (0.001-0.1mg/mL). Platelet-granulocyte complexes were analyzed in whole blood and platelet aggregometry was performed with platelet-rich plasma. Upon systemic administration of nanoparticles (1mg/kg) to anesthetized mice, ferric chloride-induced thrombus formation was measured in small mesenteric arteries using in vivo microscopy. In separate experiments, diesel (1mg/kg), titanium dioxide (1mg/kg), or single-walled nanotubes (0.01-1mg/kg) were injected into anesthetized mice and light/dye-induced thrombus formation was investigated in the cremasteric microcirculation.
  
  
  RESULTS
  Diesel and titanium dioxide nanoparticles did not activate platelets or exert prothrombotic effects. In contrast, single-walled nanotubes significantly increased platelet P-selectin expression, the number of platelet-granulocyte complexes, and platelet aggregability in vitro, and reduced the occlusion time in mesenteric arteries as well as in cremasteric arterioles.
  
  
  CONCLUSIONS
  Our study shows that single-walled carbon nanotubes, but not diesel or titanium dioxide nanoparticles, induce platelet activation in vitro and exert prothrombotic effects in the microcirculation in vivo.
authors.affiliation: Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Marchioninistrasse 27, D-81377 Munich, Germany. Peter.Bihari@med.uni-muenchen.de <Peter.Bihari@med.uni-muenchen.de>
authors.forename: Peter
authors.initials: P
authors.lastname: Bihari
authors.forename: Martin
authors.initials: M
authors.lastname: Holzer
authors.forename: Marc
authors.initials: M
authors.lastname: Praetner
authors.forename: Janos
authors.initials: J
authors.lastname: Fent
authors.forename: Max
authors.initials: M
authors.lastname: Lerchenberger
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Reichel
authors.forename: Markus
authors.initials: M
authors.lastname: Rehberg
authors.forename: Susan
authors.initials: S
authors.lastname: Lakatos
authors.forename: Fritz
authors.initials: F
authors.lastname: Krombach
mesh_terms: D000818:Animals; D001772:Blood Cell Count; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D006098:Granulocytes / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000187:drug effects*; D037742:Nanotubes, Carbon / Q000633:toxicity*; D019007:P-Selectin / Q000378:metabolism; D015539:Platelet Activation / Q000187:drug effects*; D013927:Thrombosis / Q000139:chemically induced*; D014025:Titanium / Q000633:toxicity; D001335:Vehicle Emissions / Q000633:toxicity
chemical_list: D037742:Nanotubes, Carbon; D019007:P-Selectin; D001335:Vehicle Emissions; C009495:titanium dioxide; D014025:Titanium