title: Clinical CVVH model removes endothelium-derived microparticles from circulation.
abstract: BACKGROUND
  Endothelium-derived microparticles (EMPs) are submicron vesicles released from the plasma membrane of endothelial cells in response to injury, apoptosis or activation. We have previously demonstrated EMP-induced acute lung injury (ALI) in animal models and endothelial barrier dysfunction in vitro. Current treatment options for ALI are limited and consist of supportive therapies. We hypothesize that standard clinical continuous venovenous hemofiltration (CVVH) reduces serum EMP levels and may be adapted as a potential therapeutic intervention.
  
  
  METHODS
  EMPs were generated from plasminogen activation inhibitor-1 (PAI-1)-stimulated human umbilical vein endothelial cells (HUVECs). Flow cytometric analysis was used to characterize EMPs as CD31- and annexin V-positive events in a submicron size gate. Enumeration was completed against a known concentration of latex beads. Ultimately, a concentration of ~650,000 EMP/mL perfusate fluid (total 470 mL) was circulated through a standard CVVH filter (pore size 200 μm, flow rate 250 mL/hr) for a period of 70 minutes. 0.5 mL aliquots were removed at 5- to 10-minute intervals for flow cytometric analysis. EMP concentration in the dialysate was measured at the end of 4 hours to better understand the fate of EMPs.
  
  
  RESULTS
  A progressive decrease in circulating EMP concentration was noted using standard CVVH at 250 mL/hr (a clinical standard rate) from a 470 mL volume modelling a patient's circulation. A 50% reduction was noted within the first 30 minutes. EMPs entering the dialysate after 4 hours were 5.7% of the EMP original concentration.
  
  
  CONCLUSIONS
  These data demonstrate that standard CVVH can remove EMPs from circulation in a circuit modelling a patient. An animal model of hemofiltration with induction of EMP release is required to test the therapeutic potential of this finding and potential of application in early treatment of ALI.
authors.affiliation: Children's Research Institute, Milwaukee, WI, USA ; Division of Pediatric Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA ; Clinical and Translational Science Institute of Southeast Wisconsin, Milwaukee, WI, USA.
authors.forename: Abdelhafeez H
authors.initials: AH
authors.lastname: Abdelhafeez
authors.affiliation: Children's Research Institute, Milwaukee, WI, USA ; Division of Pediatric Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Jeziorczak
authors.affiliation: Children's Research Institute, Milwaukee, WI, USA ; Division of Pediatric Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Terry R
authors.initials: TR
authors.lastname: Schaid
authors.affiliation: Clinical and Translational Science Institute of Southeast Wisconsin, Milwaukee, WI, USA.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hoefs
authors.affiliation: Children's Research Institute, Milwaukee, WI, USA ; Division of Pediatric Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Sushma
authors.initials: S
authors.lastname: Kaul
authors.affiliation: Clinical and Translational Science Institute of Southeast Wisconsin, Milwaukee, WI, USA ; Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA ; Froedtert Hospital, Milwaukee, WI, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Nanchal
authors.affiliation: Clinical and Translational Science Institute of Southeast Wisconsin, Milwaukee, WI, USA ; Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA ; Froedtert Hospital, Milwaukee, WI, USA.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Jacobs
authors.affiliation: Children's Research Institute, Milwaukee, WI, USA ; Division of Pediatric Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA ; Clinical and Translational Science Institute of Southeast Wisconsin, Milwaukee, WI, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Densmore
keywords: acute lung injury; dialysis; endothelium; microparticles