A simultaneous 3D printing process for the fabrication of bioceramic and cell-laden hydrogel core/shell scaffolds with potential application in bone tissue regeneration

, during and after 3D printing, in order to obtain a stable 3D core/shell structure and high cell viability. The whole process was carried out under conditions (neutral pH and a temperature between room temperature and 37 °C) that were gentle to the cells, so the cells incorporated into the shell remained alive throughout the 3D scaffold for the entire culture period (35 days). The core/shell structured scaffold significantly enhanced the mechanical properties when compared with a hydrogel that uses a typical cell-printing process or with a ceramic scaffold, due to the co-operative effect of each material. The compressive strength of the CDHA/alginate scaffolds in the wet state was 3.2 MPa, whereas the compressive strength of alginate could not be determined in the wet state. The 3D structural morphology of CDHA/alginate scaffolds was well retained, even after a compression test, and showed less deformation because the CDHA ceramic-core was encapsulated within the elastic alginate. The process developed in this study suggests a new cell printing model that has excellent potential for application in the field of bone tissue regeneration.