Low‐Defect Thiol‐Michael Addition Hydrogels as Matrigel Substitutes for Epithelial Organoid Derivation

Due to their selective crosslinking chemistry and well‐defined mechano‐biochemical characteristics, hydrogels crosslinked by thiol‐Michael addition reactions have garnered immense interest for 3D cell culture applications. These hydrogels are typically formed via end‐linking of bis‐cysteine oligopeptides and branched f‐functional ( f ≥ 3) poly(ethylene glycol) (PEG). Unfortunately, this gel design accumulates excessive structural defects at a solid content below ≈10% (w/v) due to diluted bifunctional components reacting intramolecularly to form primary loops that compromise the gels' mechanical integrity and lead to excessive swelling. These limitations restrict the suitability of the gels for challenging cell culture applications, such as the growth of organoids. Here, low‐defect thiol‐Michael addition (LDTM) hydrogels based on novel building blocks designed toward minimizing structural defects are reported. Compared to the conventional gels, LDTM gels can be generated at an at least 2‐fold lower solid content, while still incorporating high concentrations of bioactive ligands (≈3 × 10 ‐3 m ). LDTM gels promote the efficient development of fully patterned mouse intestinal organoids as well as human intestinal organoids, the latter in the absence of any animal‐derived components. Powerful alternatives are thus provided to the gold‐standard Matrigel, which is expensive and too variable for robust organoid development, facilitating translational applications of organoids.