(229f) Photoreversible Gel Patterning with Site-Specifically-Modified Proteins to Direct Cell Fate in 4D

As microenvironmental reconfigurations govern many important biological processes, tunable in vitro culture platforms that recapitulate such dynamic phenomena would be invaluable for fundamental studies in stem cell biology, as well as in the eventual engineering of functional human tissue¹. Preliminary efforts have exploited photochemical reactions to tether peptides spatially within hydrogels^2â??4. While such approaches have proven successful in directing 3D cell physiology, the realized biological control has been confined to relatively simple cellular functions (e.g., adhesion, proliferation). To govern more complex decisions of fate, a system that enables dynamic presentation of full-length proteins would be of great interest⁵. However, proteins are commonly recognized to be as delicate as they are powerful; careful consideration must be given to the immobilization chemistry and precise site of protein tethering to ensure sustained stability and activity. Here we present a robust synthetic strategy enabling the user-defined immobilization and subsequent release of proteins in a site-specific manner within a 3D cell culture platform, thereby preserving protein function to modulate intricate cellular behavior including stem cell differentiation, protein secretion, and cell-cell interactions.

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3. DeForest, C. A. & Anseth, K. S. Cytocompatible click-based hydrogels with dynamically tunable properties through orthogonal photoconjugation and photocleavage reactions. Nat. Chem. 3, 925â??931 (2011).

4. DeForest, C. A. & Anseth, K. S. Photoreversible Patterning of Biomolecules within Click-Based Hydrogels. Angew. Chemie Int. Ed. 51, 1816â??1819 (2011).

5. DeForest, C. A. & Tirrell, D. A. A photoreversible protein-patterning approach for guiding stem cell fate in three-dimensional gels. Nat. Mater. 14, 523â??531 (2015).