No abstract

Three-dimensional (3D) liver bioprinting is a promising technique for creating 3D liver models that can be used for in vitro drug testing, hepatotoxicity studies, and transplantation. The functional performance of 3D bioprinted liver constructs are limited by the lack of cell-cell interactions, which calls for the creation of bioprinted tissue constructs with high cell densities. This study reports the fabrication of 3D bioprinted liver constructs using a novel photocrosslinkable Gelatin Methacrylamide (GelMA)-based bioink formulation. However, the formation of excess free radicals during photoinitiation poses a challenge, particularly during photocrosslinking of large constructs with high cell densities. Hence, we designed a bioink formulation comprising the base polymer GelMA loaded with an antioxidant cocktail containing vitamin C (L-ascorbic acid) and vitamin E (α-tocopherol). We confirmed that the combination of antioxidants loaded in GelMA enhanced the ability to scavenge intracellular Reactive Oxygen Species (iROS) formed during photocrosslinking. The GelMA formulation was evaluated for biocompatibility in vitro and in vivo. These results demonstrated that the bioink had adequate rheological characteristics and was biocompatible. Furthermore, constructs with high-density primary rat hepatocytes were 3D bioprinted and showed improved cell-cell interactions and liver specific functions such as albumin and urea secretion were increased 5-fold and 2.5-fold respectively when compared with bioprinted constructs with lower cell concentrations.