Zonal and topographical differences in articular cartilage gene expression

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