title: Activated neutrophils and platelet microaggregates impede blood filterability through microchannels during simulated extracorporeal circulation.
abstract: BACKGROUND
  Neutrophil sequestration and platelet microaggregates in organ capillaries have been implicated in the inflammatory response associated with cardiopulmonary bypass. We examined the filterability of neutrophils and platelet microaggregates through silicon microchannels during simulated extracorporeal circulation. We hypothesize that blood contact with artificial surfaces over time decreases the ability of neutrophils, platelets, and their aggregates to pass through microchannels.
  
  
  METHODS
  Fresh human blood from donors (n = 9) was recirculated for 120 minutes in a simulated extracorporeal circuit. Blood samples were obtained from a donor at 0, 30, 60, and 120 minutes of recirculation. The microchannel transit time and the flow behavior of blood cells were evaluated by a silicon microchannel array flow analyzer. CD11b, L-selectin, and F-actin of neutrophils were measured by flow cytometry. Neutrophil and platelet counts and platelet aggregation to adenosine diphosphate were measured.
  
  
  RESULTS
  The microchannel transit time was prolonged during recirculation, reaching 185.9% +/- 25.6% of baseline at 120 minutes. The video microscope showed that neutrophils and platelet microaggregates plugged the microchannels. CD11b, L-selectin, and F-actin levels changed significantly by 120 minutes. Platelet counts decreased and platelet aggregability was attenuated.
  
  
  CONCLUSIONS
  Simulated extracorporeal circulation caused a progressive loss in the ability of neutrophils, platelets, and their aggregates to pass through the microchannels independent of neutrophil adhesion molecule expression.
authors.affiliation: Department of Cardiovascular Surgery, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hiramatsu
authors.forename: Yukio
authors.initials: Y
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Homma
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Enomoto
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kikuchi
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Sakakibara
mesh_terms: D000199:Actins / Q000097:blood; D000244:Adenosine Diphosphate / Q000494:pharmacology; D039481:CD11b Antigen / Q000097:blood; D005112:Extracorporeal Circulation; D005374:Filtration; D006801:Humans; D019041:L-Selectin / Q000097:blood; D007958:Leukocyte Count; D008833:Microcirculation / Q000502:physiology; D018715:Microscopy, Video; D008954:Models, Biological; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils / Q000502:physiology; D010974:Platelet Aggregation / Q000502:physiology*; D010976:Platelet Count; D012825:Silicon
chemical_list: D000199:Actins; D039481:CD11b Antigen; D019041:L-Selectin; D000244:Adenosine Diphosphate; D012825:Silicon