title: Molecular phenotyping of human chondrocyte cell lines T/C-28a2, T/C-28a4, and C-28/I2.
abstract: OBJECTIVE
  Because the immortalized chondrocyte cell lines C-28/I2, T/C-28a2, and T/C-28a4 have become a common tool in cartilage research, permitting investigations in a largely unlimited and standardized manner, we investigated the molecular phenotype of these cell lines by gene expression profiling.
  
  
  METHODS
  Complementary DNA-array analysis as well as online quantitative polymerase chain reaction were used to identify the gene expression profiles of the 3 cell lines cultured in monolayer and alginate beads, as compared with the expression profiles of cultured human adult primary chondrocytes.
  
  
  RESULTS
  A similar, but not identical, gene expression profile was established for all 3 cell lines. SOX9 was expressed at a significant level in all 3 cell lines. Extracellular matrix proteins and matrix-degrading proteases were rarely expressed. In contrast, genes involved in the cell cycle were strongly up-regulated, as compared with the expression levels in physiologic chondrocytes.
  
  
  CONCLUSIONS
  The expression of SOX9, the master gene of chondrocytic cell differentiation, reflects the basically chondrocytic phenotype of these cells. However, the major issue appears to be that these cell lines mainly proliferate and show less expression of genes involved in matrix synthesis and turnover. In this respect, C-28/I2 cells display the highest levels of matrix-anabolic and matrix-catabolic genes and thus are presumably preferable for use in investigating chondrocyte anabolic and catabolic activity and its regulation. None of the 3 cell lines appears to be a direct substitute for primary chondrocytes. A successful approach will have to validate the findings obtained with chondrocyte cell lines by using primary chondrocytes or cartilage-tissue cultures. This would permit the establishment of reproducible in vitro models and subsequently allow investigators to relate the findings to the physiologic situation.
authors.affiliation: University of Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Finger
authors.forename: C
authors.initials: C
authors.lastname: Schörle
authors.forename: A
authors.initials: A
authors.lastname: Zien
authors.forename: P
authors.initials: P
authors.lastname: Gebhard
authors.forename: M B
authors.initials: MB
authors.lastname: Goldring
authors.forename: T
authors.initials: T
authors.lastname: Aigner
mesh_terms: D000328:Adult; D000464:Alginates; D002358:Cartilage, Articular / Q000166:cytology; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002461:Cell Line, Transformed; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology*; D010450:Endopeptidases / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005819:Genetic Markers; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006609:High Mobility Group Proteins / Q000235:genetics; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D008863:Microspheres; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D055758:SOX9 Transcription Factor; D014157:Transcription Factors / Q000235:genetics
chemical_list: D000464:Alginates; D005819:Genetic Markers; D006603:Hexuronic Acids; D006609:High Mobility Group Proteins; D007375:Interleukin-1; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D014157:Transcription Factors; D020723:Glucuronic Acid; D010450:Endopeptidases