A cryopreservable cell-laden GelMa-based scaffold fabricated using a 3D printing process supplemented with an in situ photo-crosslinking

Scaffolds consisting of cylindrical struts are one of the high-potential tissue engineering materials because the highly porous structure can easily induce cell infiltration/migration and efficiently deliver nutrients to the cells. In addition, cryopreservable scaffolds have attracted much interest in tissue engineering because they can be prospective ready-to-use "living" biomaterials consisting of a patient's own cells. In this study, we investigated a cryopreservable cell-printed scaffold consisting of microscale cylindrical struts. To fabricate the scaffold, we developed a 3D cell-printing system supplemented with microfluidic channels, a core-shell nozzle, UV treatment system, and low-temperature working plate. The scaffold consisted of a cell-laden collagen/dimethyl sulfoxide (DMSO) mixture in the core region and a methacrylate gelatin (GelMA)/DMSO mixture in the shell region. After cryopreservation, the preosteoblasts (MC3T3-E1) loaded in the scaffold showed reasonable cell viability (∼85%). Moreover, no significant difference was observed in the cell proliferations and ALP activities of the cryopreserved scaffold and non-cryopreserved scaffold. Based on these results, we believe that the fabrication process can be one of the potential techniques for fabricating cryopreservable scaffolds consisting of cylindrical struts.