title: Keratinocytes modulate fetal and postnatal fibroblast transforming growth factor-beta and Smad expression in co-culture.
abstract: BACKGROUND
  The mechanism of fetal scarless wound repair is poorly understood but is thought to involve unique characteristics and behavior patterns of the fetal dermal fibroblast. The authors hypothesized that keratinocytes may differentially modulate expression of key growth factors expressed during wound healing in fetal and postnatal fibroblasts.
  
  
  METHODS
  Murine E17 fetal (n = 12 animals) and newborn (n = 8 animals) fibroblasts were grown in isolation and co-culture with newborn keratinocytes (n = 12 animals). Quantitative real-time polymerase chain reaction was performed for transforming growth factor (TGF)-beta isoform, receptor, and signaling molecule (Smad) gene expression in each group under both conditions.
  
  
  RESULTS
  At baseline, fetal fibroblasts have 1.8-fold greater TGF-beta3 expression than postnatal fibroblasts (p < 0.01). Keratinocytes induce a further increase of TGF-beta3 expression (p < 0.01) but decreased TGF-beta1, TGF-beta2, TGF-beta receptor (R)-I, and TGF-betaR-II expression in fetal fibroblasts. Keratinocytes also induce an increase in TGF-beta3 (p < 0.01) and a decrease TGF-beta2, TGF-betaR-I, and TGF-betaR-II expression in postnatal fibroblasts; however, TGF-beta1 expression is unchanged. Fetal fibroblasts have lower baseline expression of Smad3 and Smad4 than postnatal fibroblasts (p < 0.05). Keratinocytes decrease Smad3 and increase Smad7 expression in both fetal and postnatal fibroblasts (p < 0.01). In contrast, keratinocytes decrease Smad2 only in fetal fibroblasts (p < 0.05).
  
  
  CONCLUSIONS
  Keratinocytes have an overall antifibrotic influence on both fetal and postnatal fibroblasts in co-culture conditions. These data further characterize intrinsic differences between fetal and postnatal fibroblasts.
authors.affiliation: Stanford, Calif. From the Department of Surgery, Division of Plastic Surgery, Children's Surgical Research Program, Tissue Regeneration Laboratory.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Colwell
authors.forename: Rui
authors.initials: R
authors.lastname: Yun
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Krummel
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
authors.forename: H Peter
authors.initials: HP
authors.lastname: Lorenz
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D018920:Coculture Techniques; D005333:Fetus / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism*; D015603:Keratinocytes / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D051785:Smad Proteins / Q000096:biosynthesis*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*
chemical_list: D051785:Smad Proteins; D016212:Transforming Growth Factor beta