Articular cartilage and changes in arthritis. An introduction: cell biology of osteoarthritis.
The reaction patterns of chondrocytes in osteoarthritis can be summarized in five categories: (1) proliferation and cell death (apoptosis); changes in (2) synthetic activity and (3) degradation; (4) phenotypic modulation of the articular chondrocytes; and (5) formation of osteophytes. In osteoarthritis, the primary responses are reinitiation of synthesis of cartilage macromolecules, the initiation of synthesis of types IIA and III procollagens as markers of a more primitive phenotype, and synthesis of active proteolytic enzymes. Reversion to a fibroblast-like phenotype, known as "dedifferentiation", does not appear to be an important component. Proliferation plays a role in forming characteristic chondrocyte clusters near the surface, while apoptosis probably occurs primarily in the calcified cartilage.
Sandell
L J
LJ
Department of Orthopaedic Surgery, Washington University School of Medicine, 216 South Kingshighway, St Louis, MO 63110, USA. sandelll@msnotes.wustl.edu
Aigner
T
T
D000818:Animals; D002358:Cartilage, Articular / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology*; D019902:Chondrocytes / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D010003:Osteoarthritis / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology*