Fig. 1. Schematic representation of the serum-free coculture systems. (A) Monocyte/chondrocyte coculture system. Both chondrocytes (panel A, left phase contrast micrograph) and monocytes (panel A, right phase contrast micrograph) were embedded into agarose gels, stacked and cultured up to 10 days in 35 mm dishes in serum-free DMEM containing 60 µg/ml ß-aminopropionitrile fumarate, 25 µg/ml sodium ascorbate, 1 mM cysteine and 1 mM pyruvate (complete medium). (B) Macrophage/chondrocyte coculture system. Monocyte-derived macrophages (panel B, right phase contrast micrograph) were generated as adherent monolayer in a 35 mm dish and overlayered with a chondrocyte containing agarose layer (panel B, left phase contrast micrograph) as described in Materials and Methods. The cells were cultured up to 10 days in complete medium (see panel A).