Long-term maintenance of human articular cartilage in culture for biomaterial testing

Cartilage is a tissue that derives its unique mechanical and biological properties from the combination of relatively few cells and a large amount of a complex extracellular matrix. Furthermore, cartilage tissue is comparatively slow to respond to changes or harmful influences. To date, the optimal generation and long-term maintenance of cultured human articular cartilage for in vitro testing of biomaterials, poses an experimental difficulty. Experiments using cultured isolated chondrocytes in combination with scaffolds often fail to yield results comparable to the in-vivo situation. Consequently, our aim was to develop a culture method that allows in vitro maintenance of human hyaline cartilage explants in an optimal quality over an extended period of time. Such a culture could, for example, be used to determine the long-term effect of a new scaffold on intact cartilage, as an in vitro model for repair processes and to investigate biomaterial integration. In this study we compared conventional static cultures with and without serum supplementation to a serum-free perfusion culture for the ability to maintain human articular cartilage explants in a morphologically intact and differentiated state over an extended period of time of up to 56 days. Results were evaluated and compared by morphological, histochemical and immunohistochemical methods. The experiments showed that short-term maintenance of cartilage in a differentiated state for up to 14 days is possible under all culture conditions tested. However, best long-term culture results for up to 56 days were obtained with perfusion culture under serum-free conditions. Such a perfusion culture system can be used to perform biocompatabilty tests in vitro by long-term coculture of biomaterial and intact human articular cartilage.