ABSTRACT
The ECM of cartilage is primarily composed of aggrecan and collagen type II. Aggrecan is a huge proteoglycan consisting of over 100 polysaccharide chains, called glycosaminoglycans (GAGs), attached to a protein core (Alberts et al. 2007). The speci¦c GAG chains found in aggrecan are chondroitin sulfate and keratan sulfate (Alberts et al. 2007). Individual aggrecan monomers are immobilized within cartilage on a backbone of hyaluronan, creating huge aggregates that contribute to the compressive properties of the tissue (Figure 14.1) (Mow and Huiskes 2005). Collagen II forms an extensive ¦brillar network throughout the ECM to provide the tissue’s tensile strength (Mow and Huiskes 2005). Chondrocytes are specialized cells that sparsely populate articular cartilage and maintain tissue homeostasis through synthesis, organization, and remodeling of these and other ECM components.
