Human Chondrocyte Cultures as Models of Cartilage-Specific Gene Regulation

Abstract

The human adult articular chondrocyte is a unique cell type that has reached a fully differentiated state as an end point of development. Within the cartilage matrix, chondrocytes are normally quiescent and maintain the matrix constituents in a low-turnover state of equilibrium. Isolated chondrocytes in culture have provided useful models to study cellular responses to alterations in the environment such as those occurring in different forms of arthritis. However, expansion of primary chondrocytes in monolayer culture results in the loss of phenotype, particularly if high cell density is not maintained. This chapter describes strategies for maintaining or restoring differentiated phenotype by culture in suspension, gels, or scaffolds. Techniques for assessing phenotype involving primarily the analysis of synthesis of cartilage-specific matrix proteins as well as the corresponding mRNAs are also described. Approaches for studying gene regulation, including transfection of promoter-driven reporter genes with expression vectors for transcriptional and signaling regulators, chromatin immunoprecipitation, and DNA methylation are also described.

Effects of sesamin on the biosynthesis of chondroitin sulfate proteoglycans in human articular chondrocytes in primary culture

“…These morphologic alterations are accompanied by profound biochemical changes, as indicated by the reduction or total loss of aggrecan and the synthesis of type II collagen with the increased synthesis of versican CS-PG and type I collagen. However, de-differentiated chondrocytes have the capacity to re- differentiate when transferred into an environment supporting a spherical morphological formation (a pellet culture) [29]. …”

Differential limb loading in miniature pigs (Sus scrofa domesticus): a test of chondral modeling theory

“…Interestingly, a recent study demonstrated the presence of regional differences in articular chondrocyte responses to mechanical loading, suggesting the possibility that even under uniform loads different cartilage regions may not respond uniformly (Bevill et al, 2009). As chondrocytes are particularly sensitive to the three-dimensional microenvironment and differentiate in response to local signals (Lemare et al, 1998;Goldring, 2004a;Goldring, 2004b), the expression of cartilage ECM elements likely exhibit regional variation due to subtle differences in loading patterns in distinct joint regions (Bayliss et al, 1983;Nakano and Scott, 1989;Mow et al, 1990;Mizoguchi et al, 1996;Tanaka et al, 2000). It is unknown how velocity-related changes in limb posture affect load orientation.…”

Pushing the limit: masticatory stress and adaptive plasticity in mammalian craniomandibular joints

“…More recent work provides considerable support for the hypothesis that cartilage of the mandibular condyle and TMJ articular disc is affected by local biomechanical effects. Indeed, chondrocytes are highly sensitive to 3-D microenvironment and exhibit changes in differentiation status in response to environmental cues (Lemare et al, 1988;Goldring, 2004a;Goldring, 2004b), with expression of cartilage ECM elements likely reflecting regional variation due to differential loading patterns in distinct joint regions (Bayliss et al, 1983;Nakano and Scott, 1989;Mow et al, 1990;Hamrick, 1999;Tanaka et al, 2000). In this regard, it is interesting that collagen-and proteoglycan-degrading proteinases have been reported in TMJ tissues and synovial fluids (Kiyoshima et al, 1993;Kiyoshima et al, 1994;Marchetti et al, 1999;Puzas et al, 2001;Srinivas et al, 2001).…”