Highly Tunable and Cell‐Remodelable Thiol‐ene Alginate‐Peptide Crosslinked Hydrogels to Recreate Cellular and Organoid Microenvironments for Biofabrication

ABSTRACT In this study, a cell‐mediated degradable alginate hydrogel system for organoid culture and amenable to biofabrication technologies is presented. Norbornene‐functionalized alginate is crosslinked with a di‐thiolated peptide sequence cleavable by matrix metalloproteinases and decorated with cysteine‐terminated cell‐adhesion peptide RGD, upon exposure to UV. Stiffness of the hydrogels can be controlled by tuning polymer and crosslinker concentrations. Pre‐gel solutions are successfully bioprinted with a pneumatic extrusion‐based system. The hydrogels are used to encapsulate a variety of sensitive cell types. Human endometrial organoids present high cell viability, grow in size over time, present spherical morphology, and express cell–cell contacts E‐cadherin and proliferation marker Ki67. Encapsulated mouse embryonic stem cell‐derived thyroid follicles produce thyroglobulin and T4. Mouse intestinal organoids adopt a proliferative phenotype. Vascularization inside the hydrogels is achieved using endothelial cells and supporting cells (single cell suspension and spheroids). Neurite outgrowth, both small and thick bundles, from encapsulated iPSC‐derived neurospheres, demonstrates the reinnervation potential of the hydrogel. This polysaccharide hydrogel platform could be used as a defined, tunable, and ethical alternative to mouse sarcoma‐extracted basement‐membrane matrices.