An innovative cell-laden α-TCP/collagen scaffold fabricated using a two-step printing process for potential application in regenerating hard tissues

Cell-laden scaffolds are widely investigated in tissue engineering because they can provide homogenous cell distribution after long culture periods, and deposit multiple types of cells into a designed region. However, producing a bioceramic 3D cell-laden scaffold is difficult because of the low processability of cell-loaded bioceramics. Therefore, designing a 3D bioceramic cell-laden scaffold is important for ceramic-based tissue regeneration. Here, we propose a new strategy to fabricate an alpha-tricalcium-phosphate (α-TCP)/collagen cell-laden scaffold, using preosteoblasts (MC3T3-E1), in which the volume fraction of the ceramic exceeded 70% and was fabricated using a two-step printing process. To fabricate a multi-layered cell-laden scaffold, we manipulated processing parameters, such as the diameter of the printing nozzle, pneumatic pressure, and volume fraction of α-TCP, to attain a stable processing region. A cell-laden pure collagen scaffold and an α-TCP/collagen scaffold loaded with cells via a simple dipping method were used as controls. Their pore geometry was similar to that of the experimental scaffold. Physical properties and bioactivities showed that the designed scaffold demonstrated significantly higher cellular activities, including metabolic activity and mineralization, compared with those of the controls. Our results indicate that the proposed cell-laden ceramic scaffold can potentially be used for bone regeneration.