Influence of pore size on the redifferentiation potential of human articular chondrocytes in poly(urethane urea) scaffolds.

The chemical and physical properties of scaffolds affect cellular behaviour, which ultimately determines the performance and outcome of tissue-engineered cartilage constructs. The objective of this study was to assess whether a degradable porous poly(urethane urea) scaffold could be a suitable material for cartilage tissue engineering. We also investigated whether the post-expansion redifferentiation and cartilage tissue formation of in vitro expanded adult human chondrocytes could be regulated by controlled modifications of the scaffold architecture. Scaffolds with different pore sizes, < 150 µm, 150-300 µm and 300-500 µm, were seeded with chondrocytes and subjected to chondrogenic and osteogenic induction in vitro. The poly(urethane urea) scaffold with the smaller pore size enhanced the hyaline-like extracellular matrix and thus neocartilage formation. Conversely, the chondrocytes differentiated to a greater extent into the osteogenic pathway in the scaffold with the larger pore size. In conclusion, our results demonstrate that poly(urethane urea) may be useful as a scaffold material in cartilage tissue engineering. Furthermore, the chondrogenic and the osteogenic differentiation capacity of in vitro expanded human articular chondrocytes can be influenced by the scaffold architecture. By tailoring the pore sizes, the performance of the tissue-engineered cartilage constructs might be influenced and thus also the clinical outcome in the long run.