Influence of Various Alginate Brands on the Redifferentiation of Dedifferentiated Bovine Articular Chondrocytes in Alginate Bead Culture under High and Low Oxygen Tension

Abstract

We examined the influence of various alginates on the redifferentiation of dedifferentiated articular chondrocytes in alginate bead culture under low (5%) and (21%) high oxygen supply. Isolated bovine articular chondrocytes were dedifferentiated and multiplied by 2-week monolayer culture under 21% oxygen. They were subcultured at a density of 10⁷ cells/mL in six different commercially available sodium alginates (1.2%, w/v) and held under 21 or 5% oxygen for 3 weeks. Proliferation (DNA measurement on days 0 and 21 of culture), collagen type II production (immunocytochemistry and Western blotting), and [³H]proline and [³⁵S]sulfate incorporation were monitored. Collagen type II production was significantly stronger under 5% oxygen compared with 21% oxygen in two alginates (three other alginates nearly reached the significance level). However, alginatebased differences proved not to be significant. [³H]Proline incorporation was not influenced by alginate but showed strong oxygen dependency (up to 3-fold higher under 5% oxygen). For [³⁵S]sulfate incorporation oxygen dependency was even stronger (up to 8-fold higher under 5% oxygen) and significant alginate-dependent differences were found for several alginates. The effects of the different alginates did not correlate with their pH, viscosity, or guluronic:mannuronic acid ratio. Thus, the type of alginate and even more, the oxygen supply, influence the redifferentiation and matrix production of dedifferentiated bovine articular chondrocytes.