title: Elevated endothelial progenitor cells during painful sickle cell crisis.
abstract: OBJECTIVE
  Circulating endothelial progenitor cells (EPCs) counts were determined in patients with sickle cell disease (SCD) to elucidate their role in SCD-related ischemia-induced angiogenesis and reendothelialization.
  
  
  METHODS
  Circulating EPC counts (KDR(+)/CD34(+)/Cd45(dim) cells) and their relation to serum levels of EPC mobilizing growth factors erythropoietin, vascular endothelial growth factor, and interleukin-8 were investigated in SCD patients during asymptomatic state (n=66) and painful crisis (n=36) and compared to healthy controls (n=13).
  
  
  RESULTS
  EPC counts were comparable between controls (0; range, 0-1.1 cells/mL) and patients (0; range, 0-0 cells/mL) in asymptomatic state, but were significantly higher during painful crisis (41.7; range, 0-186 cells/mL; p<0.05). Also in a paired analysis of 12 patients who were included both during asymptomatic state and painful crisis, EPC counts increased significantly during painful crisis (from 0 [range, 0-0] to 26 [range, 0-149 cell/mL; p<0.05). EPC counts were not related to any of the measured growth factors.
  
  
  CONCLUSIONS
  The higher EPC counts during painful crisis might indicate a role for EPC mobilization in reendothelialization. As a relationship of EPCs with the established mobilizing growth factors, measured in this study was not observed, the mechanism of EPC mobilization in SCD remains to be elucidated.
authors.affiliation: Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam, The Netherlands.
authors.forename: Rachel T
authors.initials: RT
authors.lastname: van Beem
authors.forename: Erfan
authors.initials: E
authors.lastname: Nur
authors.forename: Jaap Jan
authors.initials: JJ
authors.lastname: Zwaginga
authors.forename: Precious P
authors.initials: PP
authors.lastname: Landburg
authors.forename: Eduard J
authors.initials: EJ
authors.lastname: van Beers
authors.forename: Ashley J
authors.initials: AJ
authors.lastname: Duits
authors.forename: Dees P
authors.initials: DP
authors.lastname: Brandjes
authors.forename: Ingrid
authors.initials: I
authors.lastname: Lommerse
authors.forename: Hetty C
authors.initials: HC
authors.lastname: de Boer
authors.forename: C Ellen
authors.initials: CE
authors.lastname: van der Schoot
authors.forename: John-John B
authors.initials: JJ
authors.lastname: Schnog
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Biemond
mesh_terms: D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood*; D042783:Endothelial Cells; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000097:blood*; D007511:Ischemia / Q000097:blood; D007958:Leukocyte Count; D008297:Male; D009389:Neovascularization, Pathologic / Q000097:blood*; D010146:Pain; D013234:Stem Cells; D042461:Vascular Endothelial Growth Factor A / Q000097:blood*
chemical_list: C508606:CXCL8 protein, human; D016209:Interleukin-8; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D004921:Erythropoietin