ABSTRACT
This chapter describes the characteristics of chondrocyte attachment and the isolation of a chondrocyte attachment factor, chondronectin, from serum using DEAE-cellulose ion exchange chromatography followed by chromatography on Cibacron blue and affinity chromatography on wheat germ agglutinin (WGA) -Sepharose. Chondronectin is also present in serum, vitreous humor, chondrocyte-conditioned medium, and extracts of cartilage, but not in extracts of other tissues. The assays for the chondrocyte attachment factor are based on the procedure developed by Klebe. Attachment of chondrocytes to collagen is low in the absence of serum. Serum stimulates the attachment of chondrocytes in a concentration dependent manner. Chondronectin activity is found in chicken, human, and fetal bovine serum. The fractions containing chondronectin activity were pooled and applied to a column of immobilized Cibacron blue F3GA. Binding of chondronectin to collagen is slow in comparison to that of fibronectin. It is likely that other substances, such as proteoglycans, participate in enhancing or stabilizing the chondronectin-collagen interaction.
