PGA‐associated heterotopic chondrocyte cocultures: implications of nasoseptal and auricular chondrocytes in articular cartilage repair

The availability of autologous articular chondrocytes remains a limiting issue in matrix assisted autologous chondrocyte transplantation. Non‐articular heterotopic chondrocytes could be an alternative autologous cell source. The aims of this study were to establish heterotopic chondrocyte cocultures to analyze cell‐cell compatibilities and to characterize the chondrogenic potential of nasoseptal chondrocytes compared to articular chondrocytes. Primary porcine and human nasoseptal and articular chondrocytes were investigated for extracellular cartilage matrix (ECM) expression in a monolayer culture. 3D polyglycolic acid‐ (PGA) associated porcine heterotopic mono‐ and cocultures were assessed for cell vitality, types II, I, and total collagen‐, and proteoglycan content. The type II collagen, lubricin, and Sox9 gene expressions were significantly higher in articular compared with nasoseptal monolayer chondrocytes, while type IX collagen expression was lower in articular chondrocytes. Only β1‐integrin gene expression was significantly inferior in humans but not in porcine nasoseptal compared with articular chondrocytes, indicating species‐dependent differences. Heterotopic chondrocytes in PGA cultures revealed high vitality with proteoglycan‐rich hyaline‐like ECM production. Similar amounts of type II collagen deposition and type II/I collagen ratios were found in heterotopic chondrocytes cultured on PGA compared to articular chondrocytes. Quantitative analyses revealed a time‐dependent increase in total collagen and proteoglycan content, whereby the differences between heterotopic and articular chondrocyte cultures were not significant. Nasoseptal and auricular chondrocytes monocultured in PGA or cocultured with articular chondrocytes revealed a comparable high chondrogenic potential in a tissue engineering setting, which created the opportunity to test them in vivo for articular cartilage repair. Copyright © 2011 John Wiley & Sons, Ltd.