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Alginate hydrogel, Dual crosslinking, In vivo tissue infiltration, Patterned biophysical properties, Patterned biochemical properties, Tissue engineering
Abstract:
Hydrogels with patterned biophysical and biochemical properties have found increasing attention in the biomaterials community. In this work, we explore alginate-based materials with two orthogonal crosslinking mechanisms: the spontaneous Diels-Alder reaction and the ultraviolet light-initiated thiol-ene reaction. Combining these mechanisms in one material and spatially restricting the location of the latter using photomasks, enables the formation of dual crosslinked hydrogels with patterns in stiffness, biomolecule presentation, and degradation, granting local control over cell behavior. Patterns in stiffness are characterized morphologically by confocal microscopy and mechanically by uniaxial compression and microindentation measurement. Mouse embryonic fibroblasts seeded on stiffness-patterned substrates attach preferably and attain a spread morphology on stiff compared to soft regions. Human mesenchymal stem cells demonstrate preferential adipogenic differentiation on soft and osteogenic differentiation on stiff surfaces. Patterns in biomolecule presentation reveal favored attachment of mouse pre-osteoblasts on stripe regions where thiolated cell-adhesive biomolecules have been coupled. Patterns in degradation are visualized by microindentation measurement following collagenase exposure and patterned tissue infiltration into degradable regions on the surface is discernible in n=5/12 samples when these materials are implanted subcutaneously into the backs of mice. Taken together, these results demonstrate that our hydrogel system with patterns in biophysical and biochemical properties enables the study of how environmental cues affect multiple cell behaviors in vitro and could be applied to guide endogenous tissue growth in diverse healing scenarios in vivo.
