Molecular phenotyping of HCS-2/8 cells as an in vitro model of human chondrocytes.
OBJECTIVE
Cultures of primary articular chondrocytes for studying chondrocyte biology are notoriously difficult to handle. One alternative is the use of chondrocytic cell lines. Because the HCS-2/8 cells are the most widely used cell line in cartilage research, we investigated the molecular phenotype of these cells by mRNA-expression profiling.


METHODS
Monolayers of HCS-2/8 cells were cultured to sub-confluence, confluence and over-confluence; primary human chondrocytes were grown in monolayer culture and alginate-bead cultures and several other chondrocytic cell lines were cultured as monolayers. RNA was isolated and analyzed by cDNA array profiling using Affymetrix GeneChips (U95A/U95Av2) and quantitative PCR.


RESULTS
Important similarities, but also remarkable differences between the HCS-2/8 cells and adult human articular chondrocytes were detected: Aggrecan and several cartilage typical collagens as well as SOX9 transcripts were strongly expressed in HCS-2/8 cells, whereas HCS-2/8 cells expressed hardly any chondrocyte-typical cartilage matrix degrading enzymes. Of all culturing conditions, clustering analysis showed that HCS-2/8 cultured at confluence are most closely related to primary chondrocytes.


CONCLUSIONS
Our study confirms how careful one needs to be in choosing in vitro model systems for investigating effects of interest. The major issue of chondrocyte cell lines appears to be that they mainly proliferate and show less expression of genes of matrix synthesis and turnover. A successful approach will have to select suitable chondrocyte cell lines and to validate findings obtained using primary chondrocytes. This allows to establish a reproducible in vitro model showing the property of interest and subsequently to relate back the obtained results to the physiologic situation.
Saas
J
J
Aventis Pharma Deutschland GmbH, Disease Group Osteoarthritis and Department of Bioinformatics Frankfurt, Germany.
Lindauer
K
K
Bau
B
B
Takigawa
M
M
Aigner
T
T
D000328:Adult; D053674:Aggrecans; D002358:Cartilage, Articular / Q000502:physiology*; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000502:physiology*; D003094:Collagen / Q000032:analysis; D017364:Collagenases / Q000032:analysis; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000032:analysis; D015870:Gene Expression / Q000235:genetics; D006609:High Mobility Group Proteins / Q000032:analysis; D006801:Humans; D037181:Lectins, C-Type; D046228:Microarray Analysis / Q000379:methods; D008954:Models, Biological; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D011509:Proteoglycans / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D055758:SOX9 Transcription Factor; D014157:Transcription Factors / Q000032:analysis
D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D006609:High Mobility Group Proteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D014157:Transcription Factors; D003094:Collagen; D017364:Collagenases