title: Concentrates containing factor IX could improve haemostasis under conditions of thrombocytopenia: studies in an in vitro model.
abstract: OBJECTIVE
  We explored the effect on haemostasis of different factor IX (FIX) concentrates under thrombocytopenic conditions using an in vitro perfusion technique.
  
  
  METHODS
  A moderate experimental thrombocytopenia (25 000-30 000 platelets/microl) was induced by means of a filtration procedure in blood anticoagulated with low-molecular-weight heparin. The effects of three different FIX concentrates - a prothrombin complex concentrate (PCC), an intermediate-purity concentrate (FIX/X), and a high-purity concentrate (HPFIX) - on platelet deposition and fibrin formation on subendothelium were assessed at two different shear rates (600/second and 1200/second). Activation of the coagulation system was monitored through assessment of prothrombin activation fragment 1 + 2 (F1 + 2).
  
  
  RESULTS
  Fibrin deposition increased after addition of FIX concentrates, but only showed a significant increase in experiments performed after incubation of PCC at the lower shear rate (600/second) (64.25 +/- 9.61% vs. control 31.22 +/- 8.02%; P < 0.05). Addition of FIX concentrates caused a small increase in the percentage of platelet deposition and area of those aggregates. These differences reached levels of statistical significance in the presence of FIX/X and HPFIX in experiments performed at a shear rate of 600/second. F1 + 2 baseline values in anticoagulated thrombocytopenic blood were 1.15 +/- 0.13 nm and reached levels of 2.49 +/- 0.24 and 3.60 +/- 0.33 nm at shear rates of 600 and 1200/second, respectively. Increments in F1 + 2 observed after addition of different FIX concentrates always remained in the previous ranges.
  
  
  CONCLUSIONS
  Data from the present study provide experimental support favouring the concept that FIX concentrates containing other activated factors could improve haemostasis under conditions of moderate thrombocytopenia.
authors.affiliation: Servicio de Hemoterapia-Hemostasia, Hospital Clinic, Barcelona, Spain. agalan@clinic.ub.es
authors.forename: A M
authors.initials: AM
authors.lastname: Galán
authors.forename: J C
authors.initials: JC
authors.lastname: Reverter
authors.forename: M
authors.initials: M
authors.lastname: Pino
authors.forename: M
authors.initials: M
authors.lastname: Viñas
authors.forename: J
authors.initials: J
authors.lastname: Bozzo
authors.forename: M R
authors.initials: MR
authors.lastname: Hernández
authors.forename: J
authors.initials: J
authors.lastname: Aznar-Salatti
authors.forename: A
authors.initials: A
authors.lastname: Ordinas
authors.forename: G
authors.initials: G
authors.lastname: Escolar
mesh_terms: D000818:Animals; D001011:Aorta; D004195:Disease Models, Animal; D005164:Factor IX / Q000494:pharmacology*; D005337:Fibrin; D006487:Hemostasis / Q000187:drug effects*; D006801:Humans; D011817:Rabbits; D013921:Thrombocytopenia / Q000188:drug therapy*
chemical_list: D005164:Factor IX; D005337:Fibrin