The effect of agarose and dexamethasone on the nature and production of extracellular matrix components by elastic cartilage chondrocytes.
Chondrocytes isolated enzymatically from rabbit ear cartilage, were cultivated in vitro in the presence of 2% agarose or 0.1 mumol/l dexamethasone. Freshly-isolated chondrocytes suspended in either Eagle's medium or 2% agarose were auto-transplanted intramuscularly. Samples were then examined by light microscopy and transmission electron microscopy. The cells cultivated in vitro rapidly formed confluent multiple overlapping layers filled with a loose matrix consisting of single collagen fibres, proteoglycans and scarce elastic fibres. The number and maturity of the elastic fibres increased substantially after dexamethasone was added. The chondrocytes in intramuscular transplants produced a larger amount of intercellular matrix with many elastic fibres than those cultured in vitro. Addition of agarose to in vitro and in vivo systems selectively suppressed the elastin production but did not diminish the production of elastic fibre microfibrils and other matrix components. This made cultures and transplants of elastic chondrocytes resemble rather hyaline cartilage than the original tissue. It seems that the lack of elastin in the matrix does not result simply from inhibition of elastin secretion or increased elastolysis. It may be related to a reversible change of genetic expression of elastic cartilage chondrocytes under the influence of agarose.
D000818:Animals; D002356:Cartilage / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D004423:Ear; D004548:Elasticity; D005109:Extracellular Matrix / Q000187:drug effects / Q000502:physiology*; D008854:Microscopy, Electron; D011817:Rabbits; D012685:Sepharose / Q000494:pharmacology*
D003907:Dexamethasone; D012685:Sepharose