Light-based 3D printing of gelatin-based biomaterial inks to create a physiologically relevant in vitro fish intestinal model

To provide prominent accessibility of fishmeal to the European population, the currently available, time- and cost-extensive feeding trials, which evaluate fish feed, should be replaced. The current paper reports on the development of a novel 3D culture platform, mimicking the microenvironment of the intestinal mucosa in vitro. The key requirements of the model include sufficient permeability for nutrients and medium size marker molecules (equilibrium within 24 hours), suitable mechanical properties (G’ < 10 kPa), and a close morphological similarity to the intestinal architecture. To enable processability with light-based 3D-printing, a gelatin-methacryloyl-aminoethyl-methacrylate (gel-MA-AEMA)-based biomaterial ink was developed and combined with Tween®20 as porogen to ensure sufficient permeability. To assess the permeability properties of the hydrogels, a static diffusion setup was utilized, indicating that the hydrogel constructs are permeable for a medium size marker molecule (FITC-dextran 4 kg·mol−1). Moreover, the mechanical evaluation through rheology evidenced a physiologically relevant scaffold stiffness (G’ = 4.83±0.78 kPa). Digital light processing (DLP)-based 3D printing of porogen-containing hydrogels resulted in the creation of constructs exhibiting a physiologically relevant microarchitecture as evidenced through cryo-scanning electron microscopy. Finally, the combination of the scaffolds with a novel Rainbow Trout (Oncorhynchus mykiss) intestinal epithelial cell line (RTdi-MI) evidenced scaffold biocompatibility.