title: Transforming growth factor-beta1 stimulates chondrogenic differentiation of posterofrontal suture-derived mesenchymal cells in vitro.
abstract: BACKGROUND
  Evidence from animal studies has associated transforming growth factor (TGF)-beta signaling with both normal and premature cranial suture fusion. However, the mechanisms whereby this pleiotropic cytokine mediates suture fusion remain uncertain. The authors established cultures of suture-derived mesenchymal cells from normally fusing (posterofrontal) and patent (sagittal) sutures and examined the in vitro effects of TGF-beta1 on these distinct cell populations.
  
  
  METHODS
  Skulls were harvested from 80 5-day-old mice. Posterofrontal and sagittal sutures were dissected, and cultures of suture-derived mesenchymal cells were established. The mitogenic, osteogenic, and chondrogenic effects of recombinant TGF-beta1 were then assessed on posterofrontal and sagittal suture-derived mesenchymal cells (1 to 10 ng/ml). Quantitative real-time polymerase chain reaction was used to examine the effects of TGF-beta1 on gene expression.
  
  
  RESULTS
  TGF-beta1 significantly decreased proliferation of both posterofrontal and sagittal suture-derived mesenchymal cells, by bromodeoxyuridine incorporation assays (n = 6). TGF-beta1 also inhibited osteogenesis in both suture-derived mesenchymal cells determined by alkaline phosphatase activity and mineralization (n = 3 for all assays). During chondrogenic differentiation, TGF-beta1 markedly increased expression of chondrocyte-specific gene markers in posterofrontal suture-derived mesenchymal cells (Sox9, Col II, Aggrecan, and Col X) (p <or= 0.05). In contrast, TGF-beta1 did not increase chondrocyte-specific gene expression in sagittal suture-derived mesenchymal cells (n = 3).
  
  
  CONCLUSIONS
  Posterofrontal suture-derived mesenchymal cells retain significant capability for both osteogenic and chondrogenic differentiation in vitro. TGF-beta1 induces in vitro chondrogenesis in posterofrontal but not sagittal suture-derived mesenchymal cells. Future studies will focus on elucidating the mechanisms whereby TGF-beta signaling mediates chondrogenesis in posterofrontal suture-derived mesenchymal cells.
authors.affiliation: Stanford, Calif. From the Hagey Pediatric Regenerative Research Laboratory and the Department of Surgery, Plastic and Reconstructive Surgery Division, Stanford University School of Medicine.
authors.forename: Yue
authors.initials: Y
authors.lastname: Xu
authors.forename: Aaron W
authors.initials: AW
authors.lastname: James
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology*; D020219:Chondrogenesis / Q000187:drug effects / Q000502:physiology; D003393:Cranial Sutures / Q000166:cytology*; D004388:Dura Mater / Q000166:cytology / Q000502:physiology; D005624:Frontal Bone / Q000166:cytology*; D015870:Gene Expression / Q000502:physiology; D066298:In Vitro Techniques; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D053773:Transforming Growth Factor beta1