title: Laser-induced primary and secondary hemostasis dynamics and mechanisms in relation to selective photothermolysis of port wine stains.
abstract: BACKGROUND
  Superficial vascular anomalies such as port wine stains are commonly treated by selective photothermolysis (SP). The endovascular laser-tissue interactions underlying SP are governed by a photothermal response (thermocoagulation of blood) and a hemodynamic response (thrombosis). Currently it is not known whether the hemodynamic response encompasses both primary and secondary hemostasis, which platelet receptors are involved, and what the SP-induced thrombosis kinetics are in low-flow venules.
  
  
  OBJECTIVE
  To (1) define the role and kinetics of primary and secondary hemostasis in laser-induced thrombus formation and (2) determine which key platelet surface receptors are involved in the hemodynamic response.
  
  
  METHODS
  532-nm laser-irradiated hamster dorsal skin fold venules were studied by intravital fluorescence microscopy following fluorescent labeling of platelets with 5(6)-carboxyfluorescein. Heparin and fluorescently labeled anti-glycoprotein Ib-α (GPIbα) and anti-P-selectin antibodies were administered to investigate the role of coagulation and platelet receptors, respectively. Lesional sizes were quantified by software.
  
  
  RESULTS
  Laser irradiation consistently produced sub-occlusive thermal coagula. Thrombosis was triggered in all irradiated venules in a thermal coagulum-independent manner and peaked at 6.25min post-irradiation. Heparin decreased the maximum thrombus size and caused thrombosis to reach a maximum at 1.25min. Immunoblocking of GPIbα abated the extent of thrombosis, whereas immunoblocking of P-selectin had no effect.
  
  
  CONCLUSIONS
  The hemodynamic response ensues the photothermal response in a thermal coagulum-independent manner and involves primary and secondary hemostasis. Primary hemostasis is mediated by constitutively expressed GPIbα but not by activation-dependent P-selectin.
authors.affiliation: Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. M.Heger@amc.uva.nl
authors.forename: Michal
authors.initials: M
authors.lastname: Heger
authors.forename: Isabelle I
authors.initials: II
authors.lastname: Salles
authors.forename: Rick
authors.initials: R
authors.lastname: Bezemer
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Cloos
authors.forename: Serge R
authors.initials: SR
authors.lastname: Mordon
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bégu
authors.forename: Hans
authors.initials: H
authors.lastname: Deckmyn
authors.forename: Johan F
authors.initials: JF
authors.lastname: Beek
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000473:pathology / Q000502:physiology; D006224:Cricetinae; D004195:Disease Models, Animal; D005456:Fluorescent Dyes; D006439:Hemodynamics; D006488:Hemostasis, Surgical; D006801:Humans; D053685:Laser Therapy; D008297:Male; D008647:Mesocricetus; D008856:Microscopy, Fluorescence; D019339:Port-Wine Stain / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*
chemical_list: D005456:Fluorescent Dyes