title: Optimization of the Expansion and Differentiation of Rabbit Chondrocytes In Vitro.
abstract: OBJECTIVE
  To develop a tissue culture expansion method for rabbit chondrocytes that promotes robust expansion while preserving chondrogenic potential.
  
  
  METHODS
  Rabbit chondrocytes isolated from articular or auricular chondrocytes were assessed for chondrogenic differentiation potential versus population doubling using different expansion and differentiation conditions. Expansion conditions included serum alone, serum plus basic fibroblast growth factor 2 (FGF-2), and serum plus insulin-like growth factor 1 (IGF-1) and FGF-2. Differentiation conditions consisted of defined medium with and without bone morphogenetic protein 2 (BMP-2).
  
  
  RESULTS
  Nonsupplemented chondrocytes showed limited expandability, whereas supplementation with FGF-2 allowed articular chondrocytes to be expanded past 10 population doublings (PDs) and allowed auricular chondrocytes to expand past 15 population doublings. Differentiation, as measured by glycosaminoglycan production in aggregate cultures, was minimal in articular chondrocytes without BMP-2 supplementation and diminished to less than 50% maximal in auricular chondrocytes by PD 20. However, when FGF-2 was used during expansion and BMP-2 used during differentiation, both articular and auricular chondrocytes retained greater than 50% maximal differentiation for more than 25 PDs. The addition of IGF-1 to FGF-2 during expansion decreased chondrogenicity of auricular chondrocytes exposed to BMP-2, whereas for articular chondrocytes, chondrogenic expression increased.
  
  
  CONCLUSIONS
  These results demonstrate that FGF-2, for expansion, and BMP-2, for differentiation, dramatically increase the functional expansion of auricular and articular chondrocytes and provide a methodology to expand sufficient numbers of chondrocytes for tissue engineering applications.
authors.affiliation: Case Western Reserve University, Cleveland, OH, USA.
authors.forename: T
authors.initials: T
authors.lastname: Mounts
authors.affiliation: Case Western Reserve University, Cleveland, OH, USA.
authors.forename: N
authors.initials: N
authors.lastname: Ginley
authors.affiliation: Case Western Reserve University, Cleveland, OH, USA.
authors.forename: M
authors.initials: M
authors.lastname: Schluchter
authors.affiliation: Case Western Reserve University, Cleveland, OH, USA ; Benaroya Research Institute, Seattle, WA, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Dennis
keywords: cartilage; growth factors; tissue culture; tissue engineering