Photoreversible Protein Patterning to Modulate 4D Stem Cell Fate

Synthetic hydrogels have emerged as a unique class of biomaterials that enable stem cells to be cultured in three-dimensions within near-physiological, simplified microenvironments.  Recent strategies have been developed that permit bioepitopes (e.g., peptides, full-length proteins) to be introduced at any point in time and space to affect cell function spatiotemporally within user-defined subvolumes of the bulk material.  While these techniques have been successfully utilized to direct a variety of basic cellular functions, advanced platforms that permit biological cues to be both introduced and subsequently removedwould be beneficial in recapitulating the dynamic abundance of signaling biomolecules in the native, temporally-variable niche.  Moreover, as proteins provide high substrate specificity in comparison with simple chemical moieties and peptides, a system that enables dynamic presentation of full-length proteins would be of great interest for use in modulating complex cellular behavior.  In this work, we demonstrate that the combination of two bioorthogonal light-based chemistries provides for the reversible immobilization of protein cues spatially within a hydrogel.  Results further highlight the versatility of such dynamic biochemical signal presentation in better understanding basic cell physiology and in directing 4D progenitor cell fate.