title: Soluble factors secreted by differentiating embryonic stem cells stimulate exogenous cell proliferation and migration.
abstract: BACKGROUND
  Stem cells are being investigated as catalysts of tissue regeneration to either directly replace or promote cellularity lost as a result of traumatic injury or degenerative disease. In many reports, despite low numbers of stably integrated cells, the transient presence of cells delivered or recruited to sites of tissue remodeling globally benefits functional recovery. Such findings have motivated the need to determine how paracrine factors secreted from transplanted cells may be capable of positively impacting endogenous repair processes and somatic cell responses.
  
  
  METHODS
  Embryonic stem cells were differentiated as embryoid bodies (EBs) in vitro and media conditioned by EBs were collected at different intervals of time. Gene and protein expression analysis of several different growth factors secreted by EBs were examined by polymerase chain reaction and enzyme-linked immunosorbent assay analysis, respectively, as a function of time. The proliferation and migration of fibroblasts and endothelial cells treated with EB conditioned media was examined compared with unconditioned and growth media controls.
  
  
  RESULTS
  The expression of several growth factors, including bone morphogenic protein-4, insulin-like growth factors and vascular endothelial growth factor-A, increased during the course of embryonic stem cell (ESC) differentiation as EBs. Conditioned media collected from EBs at different stages of differentiation stimulated proliferation and migration of both fibroblasts and endothelial cells, based on 5-bromo-2'-deoxyuridine incorporation and transwell assays, respectively.
  
  
  CONCLUSIONS
  Overall, these results demonstrate that differentiating ESCs express increasing amounts of various growth factors over time that altogether are capable of stimulating mitogenic and motogenic activity of exogenous cell populations.
authors.forename: Alyssa V
authors.initials: AV
authors.lastname: Ngangan
authors.forename: James C
authors.initials: JC
authors.lastname: Waring
authors.forename: Marissa T
authors.initials: MT
authors.lastname: Cooke
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Mandrycky
authors.forename: Todd C
authors.initials: TC
authors.lastname: McDevitt
mesh_terms: D016475:3T3 Cells; D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D002465:Cell Movement; D049109:Cell Proliferation; D017077:Culture Media, Conditioned / Q000494:pharmacology; D058732:Embryoid Bodies / Q000166:cytology / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D051379:Mice; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D017077:Culture Media, Conditioned; D042461:Vascular Endothelial Growth Factor A; D004815:Epidermal Growth Factor