Immobilized articular chondrocytes: in vitro production of extracellular matrix compounds

Primary cultivated rabbit articular chondrocytes were immobilized in calcium alginate beads. Both free and entrapped cells were allowed to grow under normal conditions. After bead lysis, harvested cells showed normal growth patterns when resuspended in culture medium. After long-term immobilization, the morphology and the viability of immobilized rabbit articular chondrocytes were preserved: cells remained viable and were able to grow and divide for several days inside the alginate beads in a culture incubator. The percentage of viable cells did not significantly decrease when immobilized cells were stored at 4 degrees C for 30 days. The basic metabolic properties (glucose consumption) and characteristic activities (proteoglycan secretion) were similar to those of free adherent cells with a time-dependent increase. A large scale bioproduction of extracellular matrix components may be considered of great interest for the ready-to-use complete culture systems of mammalian cells with high densities. Moreover immobilized forms also facilitate the use of cells in a bioreactor or in some unusual conditions (parabolic flights).