title: Uremia causes endothelial progenitor cell deficiency.
abstract: BACKGROUND
  Circulating bone marrow-derived endothelial progenitor cells (EPCs) promote vascular repair. Their number in peripheral blood correlates with endothelial function and cardiovascular risk in humans. We explored whether uremia influences the number of EPCs.
  
  
  METHODS
  We assessed circulating CD34+ hematopoietic progenitor cells in whole blood using flow cytometry and EPCs (in vitro assay) in 46 patients with advanced renal failure and in 46 age- and gender-matched healthy subjects. Further, the effect of uremia on EPC differentiation was studied in vitro and in vivo.
  
  
  RESULTS
  Both in renal patients (r= 0.34, P < 0.02) and in healthy subjects (r= 0.32, P= 0.04) the number of EPCs was significantly correlated to the absolute number of CD34+ hematopoietic progenitor cells. Renal patients had significantly fewer EPCs than healthy subjects, however (167 +/- 15 cells/high power field vs. 235 +/- 17 cells/high power field; P < 0.05). Uremic serum significantly (P < 0.05) inhibited EPC differentiation and functional activity in vitro. Amelioration of uremia after institution of renal replacement therapy in patients with terminal renal failure also significantly (P < 0.05) increased the number of EPCs.
  
  
  CONCLUSIONS
  Uremia inhibits differentiation of EPCs. This may impair cardiovascular repair mechanisms in patients with renal failure.
authors.affiliation: Division of Nephrology, Department of Internal Medicine Hannover Medical School, Hannover, Germany. groot.kirsten.de@mh-hannover.de
authors.forename: Kirsten
authors.initials: K
authors.lastname: de Groot
authors.forename: Ferdinand Hermann
authors.initials: FH
authors.lastname: Bahlmann
authors.forename: Johanna
authors.initials: J
authors.lastname: Sowa
authors.forename: Jana
authors.initials: J
authors.lastname: Koenig
authors.forename: Jan
authors.initials: J
authors.lastname: Menne
authors.forename: Hermann
authors.initials: H
authors.lastname: Haller
authors.forename: Danilo
authors.initials: D
authors.lastname: Fliser
mesh_terms: D002452:Cell Count; D002454:Cell Differentiation; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000473:pathology*; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000473:pathology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D017582:Renal Replacement Therapy; D014511:Uremia / Q000473:pathology*