INTEGRIN EXPRESSION AND COLLAGEN TYPE II IMPLICATED IN MAINTENANCE OF CHONDROCYTE SHAPE IN MONOLAYER CULTURE: AN IMMUNOMORPHOLOGICAL STUDY

Authors


Correspondence should be addressed to: Dr Mehdi Shakibaei, Institute of Anatomy, Free University of Berlin, Königin-Luise-Strasse 15, D-14195 Berlin, Germany.

Abstract

Chondrocytes grown in monolayer culture at low density, with serum added, either dedifferentiate after several days whereby their cell shape changes or they are overgrown by fibroblast-like cells. The aim of this study was to optimize the cultivation of chondrocytes in monolayer culture and to slow down their transformation or their overgrowth by fibroblast-like cells. For this purpose freshly isolated chondrocytes of cartilage anlagen from 17-day-old mouse embryos were grown on plastic or collagen type II-coated substrates. With this model: (a) chondrocytes grown on plastic substrates had almost completely changed to fibroblast-like cells after 5 days in culture. (b) When grown on collagen type II, the chondrocytes maintained their round phenotype for more than 2 weeks in culture. (c) Immunomorphological investigations showed that chondrocytes produce collagen type II and fibronectin and express specific surface receptors (integrins of the β1-group) on the membrane from day 1 until the end of the culture period when grown on collagen type II. (d) Treatment with β1-integrin antibodies clearly reduces chondrocyte adhesion on collagen type II by about 70%. Hence, these data indicate that the most probable influence of collagen type II on cellular behaviour depends on the integrins participating in a chondrocyte—collagen type II interaction, and this model represents a pure chondrocyte culture which allows cell growth for an extended period.

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