title: Isolation and characterization of murine mandibular condylar cartilage cell populations.
abstract: OBJECTIVE
  The mandibular condylar cartilage is a heterogeneous tissue containing cells at various stages of chondrocyte maturation organized into 4 zones: superficial, polymorphic, flattened, and hypertrophic. The goal of this study was to use transgenic mice containing chondrocyte maturation markers fused to fluorescent protein transgenes to isolate and characterize homogenous cell populations of the mandibular condylar cartilage.
  
  
  METHODS
  Fluorescent reporter expression in the mandibular condylar cartilage of transgenic mice containing the 3.6-kb fragment of the rat collagen type 1 promoter fused to a topaz-fluorescent protein (Col3.6-tpz), collagen type 2 promoter fused to a cyan-fluorescent protein (Col2-cyan), and/or collagen type 10 promoter fused to cherry-fluorescent protein (Col10-cherry) was examined. Mandibular condylar cartilage cells were analyzed by fluorescence-activated cell sorting (FACS) and either used for gene expression analysis or plated in cell cultures and exposed to adipogenic, osteogenic, or chondrogenic conditions. To determine cell fate, transgenic mice containing the Col3.6-cre recombinase were bred with cre reporter mice.
  
  
  RESULTS
  Localization and analysis of gene expression revealed that Col3.6-tpz-positive cells corresponded to the polymorphic/flattened zones and Col2-cyan-positive cells corresponded to the flattened/hypertrophic zones of the mandibular condylar cartilage. Mandibular condylar cartilage FACS-sorted Col3.6-tpz-positive cells have the potential to differentiate into bone, cartilage, and fat. Cell fate mapping revealed that Col3.6 cells are precursors of some of the hypertrophic chondrocytes in the mandibular condylar cartilage.
  
  
  CONCLUSIONS
  Col3.6-tpz cells represent an earlier stage of the mandibular condylar cartilage maturation pathway.
authors.affiliation: Division of Orthodontics, Department of Craniofacial Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: A
authors.initials: A
authors.lastname: Utreja
authors.forename: Z
authors.initials: Z
authors.lastname: Kalajzic
authors.forename: T
authors.initials: T
authors.lastname: Sobue
authors.forename: D
authors.initials: D
authors.lastname: Rowe
authors.forename: S
authors.initials: S
authors.lastname: Wadhwa
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism; D018929:Cell Culture Techniques; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D008335:Mandibular Condyle / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D051381:Rats; D013704:Temporomandibular Joint / Q000166:cytology / Q000378:metabolism