In vitro and in vivo biocompatibility evaluation of a 3D bioprinted gelatin-sodium alginate/rat Schwann-cell scaffold

Peripheral nerve injuries often cause different degrees of sensory and motor function loss. Currently, the repair effect of the "gold standard", autologous nerve transplantation, is unsatisfactory. Tissue engineering has the potential to tissue manipulation, regeneration, and growth, but achieving personalization and precision remains a challenge. In this study, we used 3D bioprinting to construct a nerve scaffold composed of gelatin/alginate hydrogel containing rat Schwann cells. On day 1 after printing, the Schwann cell survival rate was 91.87 +/- 0.55%. Cells could be cultured in the hydrogel for 7 days, and were well attached to the surface of the scaffold. On days 4 and 7, the 3D bioprinted scaffold released higher levels of nerve growth factor (NGF) than 2D culture group. Further, the mRNA levels of NGF, brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), and platelet-derived growth factor (PDGF) expressed on day 4 by Schwann cells were higher in the 3D bioprinted scaffold culture than in 2D culture. After 4 weeks of implantation, the cell-containing scaffold still showed partial lattice structure and positive S-100 beta immunofluorescence. These results indicated that the 3D bioprinted gelatin-sodium alginate/Schwann-cell composite scaffold improved cell adhesion and related factor expression. This 3D bioprinted composite scaffold showed good biocompatibility and could be a promising candidate in neural tissue engineering in the future.