Bioprinting of GelMA/PEGDA Hybrid Bioinks for SH-SY5Y Cell Encapsulation: Role of Molecular Weight and Concentration.

Current clinical interventions for large peripheral nerve gap injuries are limited. Bioprinting provides opportunities to develop tissue engineered constructs that provide a biomimetic environment to guide nerve regeneration. However, hydrogels that are cell-instructive, mechanically compliant, and have an appropriate biodegradation profile for nerve guidance conduit applications are limited. In this study, a photocrosslinkable gelatin methacryloyl (GelMA) and polyethylene glycol diacrylate (PEGDA) hybrid bioink is developed. The role of PEGDA molecular weight and concentration in tuning the hydrogel physicochemical and biological properties is evaluated. PEGDA modulated the hydrogel network structure and properties in a molecular weight and concentration dependent manner. A lower molecular weight and high concentration induced high crosslinking density thus improving compressive modulus, lower swelling, and a slower degradation profile. The bioinks showed good printability and are able to fabricate multi-layer constructs with high shape fidelity and flexibility. The SH-SY5Y cells maintained high cell viability after bioprinting in all bioinks. However, cells showed limited metabolic activity and spreading in the GelMA/PEGDA hydrogels with both high concentration and molecular weight. This preliminary study provides guidance on the use of specific molecular weights and concentrations in GelMA/PEGDA bioinks for the bioprinting of SH-SY5Y cells.