Confocal analysis of cytoskeletal organisation within isolated chondrocytesub-populations cultured in agarose

This study reports the cytoskeletal organisation within chondrocytes, isola ted from the superficial and deep zones of articular cartilage and seeded i nto agarose constructs. At day 0, marked organisation of actin microfilamen ts was not observed in cells from both zones. Partial or clearly organised microtubules and vimentin intermediate filaments cytoskeletal components we re present, however, in a proportion of cells. Staining for microtubules an d vimentin intermediate filaments was less marked after 1 day in culture ho wever than on initial seeding. For all three cytoskeletal components there was a dramatic increase in organisation between days 3 and 14 and, in gener al, organisation was greater within deep zone cells. Clear organisation for actin microfilaments was characterised by a cortical network and punctate staining around the periphery of the cell, while microtubules and vimentin intermediate filaments formed an extensive fibrous network. Cytoskeletal or ganisation within chondrocytes in agarose appears, therefore, to be broadly similar to that described in situ. Variations in the organisation of actin microfilaments between chondrocytes cultured in agarose and in monolayer a re consistent with a role in phenotypic modulation. Vimentin intermediate f ilaments and microtubules form a link between the plasma membrane and the n ucleus and may play a role in the mechanotransduction process.