title: Cord blood mesenchymal stromal cell-conditioned medium protects endothelial cells via STAT3 signaling.
abstract: OBJECTIVE
  Cell-based therapies may be useful for treating ischemic diseases, but the underlying mechanisms are incompletely understood. We investigated the impact of cord blood mesenchymal stromal cell (CBMSC)- or fibroblast (FB)-secreted factors on starved endothelial cells and determined the relevant intracellular signaling pathways.
  
  
  METHODS
  HUVECs were subjected to glucose/serum deprivation (GSD) in hypoxia or normoxia, in presence of CBMSC- or FB-conditioned medium (CM). Viability and proliferation were determined via WST-8 conversion and BrdU incorporation. Apoptosis was quantified by annexin V/ethidium homodimer-III staining, nuclear fragmentation and cell morphology. mRNA expression and protein phosphorylation were determined by real-time qPCR and western blot. Experiments were repeated in presence of small-molecule inhibitors.
  
  
  RESULTS
  The negative impact of GSD was most pronounced at 21% O2. Here, medium of CBMSCs and FBs increased viability and proliferation and reduced apoptosis of HUVECs. This was associated with increased STAT3 and ERK1/2 phosphorylation and BCL-2 expression. Under STAT3 inhibition, the beneficial effect of CBMSC-CM on viability and BCL-2 expression was abolished.
  
  
  CONCLUSIONS
  Factors released by CBMSCs protect endothelial cells from the deleterious impact of GSD by activation of the STAT3 survival pathway. However, this phenomenon is not CBMSC-specific and can be reproduced using juvenile fibroblasts.
authors.affiliation: Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Berlin, Germany.
authors.forename: Andreas Matthaeus
authors.initials: AM
authors.lastname: Bader
authors.forename: Andreja
authors.initials: A
authors.lastname: Brodarac
authors.forename: Kristin
authors.initials: K
authors.lastname: Klose
authors.forename: Karen
authors.initials: K
authors.lastname: Bieback
authors.forename: Yeong-Hoon
authors.initials: YH
authors.lastname: Choi
authors.forename: Kyung-Sun
authors.initials: KS
authors.lastname: Kang
authors.forename: Andreas
authors.initials: A
authors.lastname: Kurtz
authors.forename: Christof
authors.initials: C
authors.lastname: Stamm
mesh_terms: D001483:Base Sequence; D017077:Culture Media, Conditioned; D017931:DNA Primers; D005312:Fetal Blood / Q000166:cytology*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D060888:Real-Time Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D017077:Culture Media, Conditioned; D017931:DNA Primers; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human