Zonal and topographical differences in articular cartilage gene expression

Eric M. Darling, Jerry C Y Hu, Kyriacos A. Athanasiou

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


Articular cartilage is composed of phenotypically different zones. In young articular cartilage, there are only two distinct zones: superficial and growth. The zones have different mechanical properties and play specific roles within functional cartilage tissue. In small animal models, it is difficult to separate the zones quickly and efficiently using only a dissecting microscope. Surface abrasion is a method that has been developed to harvest cells from articular cartilage to produce highly purified samples in a simple, reproducible process. Using this harvesting technique, the superficial zone has been separated from the underlying growth zone. Superficial cells comprised approximately 4% of the total cells obtained. Superficial and growth zone chondrocytes from articular cartilage were analyzed using real-time RT-PCR. Expressed superficial zone protein was 3-fold greater in the superficial zone population than in the growth zone population (p<0.01). This, along with histological evidence, indicates that surface abrasion is successful as a zonal separation technique. Additionally, type II collagen was expressed 8-fold more abundantly in the growth zone than in the superficial zone (p<0.005). There was no difference in aggrecan expression between the two zones. Regional variations among the femoral groove and medial and lateral condyles were also examined. No significant variations in SZP, type II collagen, or aggrecan were found, which makes the pooling of zonal cells from different regions an acceptable option for tissue engineering studies.

Original languageEnglish (US)
Pages (from-to)1182-1187
Number of pages6
JournalJournal of Orthopaedic Research
Issue number6
StatePublished - Nov 2004
Externally publishedYes


  • Articular cartilage
  • Gene expression
  • Tissue engineering
  • Zonal separation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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