Properties of cultured chondrocytes obtained from histologically distinct zones of the chick embryo tibiotarsus.

Abstract. Chondrocytes at different stages of cellular differentiation were isolated from the tarsal element (immature chondrocytes) and zones 2 and 3 (mature chondrocytes) of 12-d chick embryo tibiotarsus. The chondrocytes from the two sources differed in their cell morphologies, growth rate and production of type X collagen . In 24 h, zone 2 and 3 chondrocytes synthesized 800 times more type X collagen than tarsal chondrocytes . The effect of exogenous CaC12 (5 and 10 mM) on the synthesis of type X collagen by both mature and immature chondrocytes was tested.

Section: Induction Of Type X Collagen Synthesis In Tarsal Chondrocytesmentioning

confidence: 92%

Elevated extracellular calcium concentrations induce type X collagen synthesis in chondrocyte cultures.

Bonen

Schmid

1991

“…Cartilages were dissected from 14-or 20-d-old chicken embryos (Spafas Inc., Norwich, CT). Hypertrophic chondrocytes were from the hypertrophic zone three (Kim and Conrad, 1977;Stocum et al, 1979;Schmid and Conrad, 1982 a ) of the tibia. Non-hypertrophic chondrocytes were from the caudal one-third of the sternum.…”

Section: Chondrocyte Culturementioning

confidence: 99%

Plasma Transglutaminase in Hypertrophic Chondrocytes: Expression and Cell-specific Intracellular Activation Produce Cell Death and Externalization

Nurminskaya

Magee

Nurminsky

et al. 1998

We previously used subtractive hybridization to isolate cDNAs for genes upregulated in chick hypertrophic chondrocytes (Nurminskaya, M., and T.F. Linsenmayer. 1996. Dev. Dyn. 206:260–271). Certain of these showed homology with the “A” subunit of human plasma transglutaminase (factor XIIIA), a member of a family of enzymes that cross-link a variety of intracellular and matrix molecules. We now have isolated a full-length cDNA for this molecule, and confirmed that it is avian factor XIIIA. Northern and enzymatic analyses confirm that the molecule is upregulated in hypertrophic chondrocytes (as much as eightfold). The enzymatic analyses also show that appreciable transglutaminase activity in the hypertrophic zone becomes externalized into the extracellular matrix. This externalization most likely is effected by cell death and subsequent lysis—effected by the transglutaminase itself. When hypertrophic chondrocytes are transfected with a cDNA construct encoding the zymogen of factor XIIIA, the cells convert the translated protein to a lower molecular weight form, and they initiate cell death, become permeable to macromolecules and eventually undergo lysis. Non-hypertrophic cells transfected with the same construct do not show these degenerative changes. These results suggest that hypertrophic chondrocytes have a novel, tissue-specific cascade of mechanisms that upregulate the synthesis of plasma transglutaminase and activate its zymogen. This produces autocatalytic cell death, externalization of the enzyme, and presumably cross-linking of components within the hypertrophic matrix. These changes may in turn regulate the removal and/or calcification of this hypertrophic matrix, which are its ultimate fates.

“…Embryonic chick chondrocytes were released from stage 38 tibiae (Hamburger and Hamilton, 1951), zone II cartilage segments (Kim and Conrad, 1977), by trypsin (type II)/collagenase (type II; Wbrthington, Freehold, NJ) treatment (Knudson and Toole, 1985). Rat chondrosareoma chondrocytes from long-term continuous cell cultures were obtained from Dr. James H.…”

Section: Chondrocytes and Culture Conditionsmentioning

confidence: 99%

Hyaluronan receptor-directed assembly of chondrocyte pericellular matrix.

Knudson

1993

269

250

Abstract. Initial assembly of extracellular matrix occurs within a zone immediately adjacent to the chondrocyte cell surface termed the cell-associated or periceUular matrix. Assembly within the periceUular matrix compartment requires specific cell-matrix interactions to occur, that are mediated via membrane receptors. The focus of this study is to elucidate the mechanisms of assembly and retention of the cartilage pericellular matrix proteoglycan aggregates important for matrix organization. Assembly of newly synthesized chondrocyte pericellular matrices was inhibited by the addition to hyaluronan hexasaccharides, competitive inhibitors of the binding of hyaluronan to its cell surface receptor. Fully assembled chondrocyte pericellular matrices were displaced using hyaluronan hexasaccharides as well.When exogenous hyaluronan was added to matrixfree chondrocytes in combination with aggrecan, a pericellular matrix equivalent in size to an endogenous matrix formed within 30 min of incubation. Addition of hyaluronan and aggrecan to glutaraldehyde-fixed chondrocytes resulted in matrix assembly comparable to live chondrocytes. These matrices could be inhibited from assembling by the addition of excess hyaluronan hexasaccharides or displaced once assembled by subsequent incubation with hyaluronan hexasaccharides. The results indicate that the aggrecanrich chondrocyte pericellular matrix is not only on a scaffolding of hyaluronan, but actually anchored to the cell surface via the interaction between hyaluronan and hyaluronan receptors.