Intestinal mucosa-mimetic double-layer gelatin hydrogel for recapitulation of 3D immune microenvironment

The intestinal immune microenvironment plays a crucial role in regulating systemic immune responses and is implicated in various diseases. Nevertheless, no existing model simultaneously replicates the three-dimensional (3D) immune microenvironment and the mucosal barrier. This study presents a novel mucosa-mimic model that consists of a cell-laden hydrogel matrix and a pseudo-mucus layer that emulate the intestinal lamina propria and mucosal barrier, respectively. The model was used to evaluate the response of 3D-cultured dendritic cells (DCs) to antigens infiltrating the native mucus-like barrier, and to simulate the role played by mucus in modulating DC activity. To mimic the intestinal tissue and residing DCs, monocytes were encapsulated in photo-crosslinked gelatin-methacrylate hydrogels and differentiated into DCs. In this 3D system, monocyte differentiation into DCs was more effective than in a two-dimensional system. The pseudo-mucus layer of gelatin and mucin exhibited molecular size-dependent permeability and enhanced the immune activity of monocyte-derived DCs. When exposed to a model antigen, DC maturation within the mucosa-mimetic hydrogel was confirmed by measuring the levels of mRNAs encoding DC maturation markers. The results emphasize that the hydrogel-based mucosal platform serves as a robust tool for assessment of intestinal immune reactions.