Comparison of gene expression profile between human chondrons and chondrocytes: a cDNA microarray study.
OBJECTIVE
The chondron is a basic unit of articular cartilage that includes the chondrocyte and its pericellular matrix (PCM). This current study was designed to investigate the effects of the chondron PCM on the gene expression profile of chondrocytes.


METHODS
Chondrons and chondrocytes were enzymatically isolated from human articular cartilage, and maintained in pellet culture. Pellets of chondrons or chondrocytes were collected at days 1, 3 and 5 for cDNA microarray analysis.


RESULTS
In comparison with chondrocytes alone, chondrons had 258 genes, in a broad range of functional categories, either up- or downregulated at the three time points tested. At day 1, 26 genes were significantly upregulated in chondrons and four downregulated in comparison to chondrocytes. At day 3, the number of upregulated chondron genes was 97 and the number downregulated was 43. By day 5, there were more downregulated genes (56) than upregulated genes (32) in chondrons. Upregulation of a group of heat shock proteins (HSPA1A, HSPA2 and HSPA8) in chondrons was validated by real time reverse transcription polymerase chain reaction (RT-PCR). Genes related to chondrocyte hypertrophy and dedifferentiation such as SSP1 and DCN were downregulated in chondrons as compared to the expression in chondrocytes.


CONCLUSIONS
The presence of the PCM in chondrons has a profound influence on chondrocyte gene expression. Upregulation of the heat shock protein 70 may contribute to the robustness and active matrix production of chondrons. The intact PCM may further stabilize the phenotype of chondrocytes within chondrons.
Zhang
Z
Z
Department of Biomedical Engineering, Johns Hopkins University, 3400 N. Charles Street, Clark Hall 102, Baltimore, MD 21218, USA. zhangzj@jhu.edu
Fan
J
J
Becker
K G
KG
Graff
R D
RD
Lee
G M
GM
Francomano
C A
CA
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000328:Adult; D051017:Apoptosis Regulatory Proteins; D002358:Cartilage, Articular / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000502:physiology*; D004270:DNA, Circular / Q000235:genetics; D058575:Decorin; D015536:Down-Regulation / Q000235:genetics; D005109:Extracellular Matrix / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D020869:Gene Expression Profiling / Q000379:methods*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020370:Osteoarthritis, Knee / Q000235:genetics*; D053495:Osteopontin; D011509:Proteoglycans / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012795:Sialoglycoproteins / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C414431:BAG3 protein, human; C546878:DCN protein, human; D004270:DNA, Circular; D058575:Decorin; D016326:Extracellular Matrix Proteins; D018840:HSP70 Heat-Shock Proteins; D011509:Proteoglycans; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D053495:Osteopontin