title: Angiopoietin-2 modulates eEOC-mediated renoprotection in AKI in a dose-dependent manner.
abstract: BACKGROUND
  Early endothelial outgrowth cells (eEOCs) significantly protect mice from acute kidney injury (AKI). Angiopoietin-2 (Ang-2) has been shown to be critically involved in vascular repair and homeostasis. The aim of this study was to investigate consequences of Ang-2 treatment of syngeneic murine eEOCs in a cell-based therapeutic approach for AKI.
  
  
  METHODS
  Male 8- to 12-week-old C57/Bl6N mice, subjected to unilateral renal ischemia (40 minutes) postuninephrectomy were systemically injected with 0.5 × 10(6) untreated or Ang-2-pretreated syngeneic murine eEOCs. Renal function and morphology were analyzed 48 hours later. Cellular consequences of eEOC treatment with Ang-2 were evaluated using different in vitro assays (direct and indirect migration, apoptosis/necrosis, ELISA studies).
  
  
  RESULTS
  Administration of untreated eEOCs did not protect mice from AKI. Ang-2 dose-dependently modulated cell effects in AKI. While incubating the cells at a concentration of 200 ng/mL (1 hour) did not have any effect on renal function, doubling the concentration (400 ng/mL) resulted in significant renoprotection of cell-injected mice. With 800 ng/mL, cell injection dramatically worsened renal function of treated animals. In vitro analysis showed significantly accelerated migration of cultured mature endothelial cells after incubation with supernatant from Ang-2-treated eEOCs (200 and 400 ng/mL). These effects were most pronounced with 400 mg/mL. In addition, Ang-2 promoted survival of eEOCs. Cellular releases of VEGF and IL-6 were decreased by Ang-2, while TGF-β levels in the medium of Ang-2-stimulated eEOCs were not different from those in untreated cells.
  
  
  CONCLUSIONS
  Ang-2 acts as modulator of eEOCs in AKI. The migration analysis indicates that the Ang-2 significantly alters indirect (paracrine) activity of eEOCs, thus promoting renoprotection in a dose-dependent manner.
authors.affiliation: Department of Nephrology and Rheumatology, University Hospital of Göttingen, Göttingen, Germany. d.patschan@gmail.com
authors.forename: Daniel
authors.initials: D
authors.lastname: Patschan
authors.forename: Rico
authors.initials: R
authors.lastname: Backhaus
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Elle
authors.forename: Katrin
authors.initials: K
authors.lastname: Schwarze
authors.forename: Elvira
authors.initials: E
authors.lastname: Henze
authors.forename: Jan Ulrich
authors.initials: JU
authors.lastname: Becker
authors.forename: Susann
authors.initials: S
authors.lastname: Patschan
authors.forename: Gerhard Anton
authors.initials: GA
authors.lastname: Müller
mesh_terms: D058186:Acute Kidney Injury / Q000188:drug therapy*; D042702:Angiopoietin-2 / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D042702:Angiopoietin-2