Cartilage tissue engineering using funnel-like collagen sponges prepared with embossing ice particulate templates

Three-dimensional porous scaffolds of collagen have been widely used for tissue engineering and regenerative medicine. In this study, we fabricated funnel-like collagen sponges with open surface pore structures by a freeze-drying method that used embossing ice particulates as a template. By controlling the size of the ice particulates and the temperature of freezing, collagen sponges with different pore structures were prepared. To investigate the effects of different pore structures on cartilage regeneration, the funnel-like collagen sponges were used to culture bovine articular chondrocytes. Scaffolds that were prepared with 400 μm ice particulate templates and a freezing temperature of −3 °C resulted in the best cell distribution, ECM production, and chondrogenesis. Although funnel-like collagen sponges prepared with 400 μm ice particulate templates and a freezing temperature of −1 °C and 720 μm ice particulates and a freezing temperature of −3 °C, showed even cell distribution, the cell seeding efficiencies and sGAG amount per cell were low. However, the scaffolds prepared with 400 μm ice particulate templates and a freezing temperature of −5 °C or −10 °C showed a limited effect on the improvement of cell distribution and chondrogenesis. Control collagen sponges without ice particulates failed to support the formation of homogenous cartilage-like tissue. These results indicate that funnel-like collagen sponges were superior to control collagen sponges and that scaffolds prepared with 400 μm ice particulate templates at −3 °C were optimal for cartilage tissue engineering.