title: Intermittent flow increases endotoxin-induced adhesion of human erythrocytes to vascular endothelial cells.
abstract: OBJECTIVE
  To investigate the effects of different conditions of flow on endotoxin induced adhesion of human red blood cells (RBC) to human umbilical vein endothelial cells (HUVEC).
  
  
  METHODS
  Prospective, randomized, controlled in vitro study in a university-affiliated cell biology laboratory. SUBJECTS. Human erythrocytes, human vascular endothelial cells.
  
  
  METHODS
  Superfusion of HUVEC monolayers with human erythrocytes incubated with either saline (CON) or endotoxin (ETX) with different flow pattern (basic flow rates of 0.65 or 1.3 ml/min; intermittent flow, IMF). The CON/0.6, CON/1.3, CON-IMF/1.3 ( n=7/group) groups served as control, and in test groups ETX/0.6, ETX/1.3, ETX-IMF/0.6, and ETX-IMF/1.3 ( n=7/group) both RBC and HUVECs were incubated with ETX and flow pattern and rates varied. In the IMF experiments flow rates of 0.65 and 1.3 ml/min were combined with stop-and-go flow pattern.
  
  
  RESULTS
  At continuous flow of 0.65 ml/min erythrocyte adhesion was 61+/-5 cells/mm(2) in CON and 172+/-25 cells/mm(2) after ETX. When flow rate was increased to 1.3 ml/min, adhesion decreased to 27+/-4 cells/mm(2) in CON and 93+/-18 cells/mm(2) after ETX. IMF conditions had no effect on RBC adhesion of naive RBC but increased the number of adhesive erythrocytes after incubation with ETX both at 0.65 ml/min (287+/-33 cells/mm(2)) and at 1.3 ml/min (148+/-13 cells/mm(2)).
  
  
  CONCLUSIONS
  RBC adhesion to vascular endothelium is affected by rate and pattern of blood flow. Higher flow rates or shear forces reduce RBC adhesion while stop-and-go flow pattern favored adhesion of ETX-treated erythrocytes to HUVECs. These findings suggest that altered RBCs interact with altered flow patterns potentially contributing to the microcirculatory injury observed in sepsis.
authors.affiliation: A.C. Burton Vascular Biology Laboratory, London Health Sciences Centre, University of Western Ontario, 800 Commissoners Road East, London, Ontario N6A 4G5, Canada.
authors.forename: Otto
authors.initials: O
authors.lastname: Eichelbrönner
authors.forename: William J
authors.initials: WJ
authors.lastname: Sibbald
authors.forename: Ian H
authors.initials: IH
authors.lastname: Chin-Yee
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D004730:Endothelium, Vascular; D004731:Endotoxins / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects*; D006801:Humans; D014471:Umbilical Veins
chemical_list: D004731:Endotoxins