(108e) Modular Hydrogels Based On Click Chemistry for 3D Stem Cell Encapsulation and Transplantation

Synthetic biomaterials that mimic the native extracellular matrix (ECM) provide an excellent platform to study the effect of microenvironmental cues on cell behavior. However, the complexity and heterogeneity of the ECM make it difficult to recapitulate essential cues from the native microenvironment while retaining independent control of essential matrix parameters such as stiffness and biochemical functionality. Here we present a versatile platform based on hyaluronic acid (HA) that is functionalized and crosslinked using click chemistry for the creation of designer three-dimensional (3D) ECMs. We synthesized HA-dibenzocyclooctyne (HA-DBCO) as a biocompatible backbone and functionalized it with ECM-derived peptide ligands using the Strain-Promoted Azide-Alkyne Cycloaddition (SPAAC) click reaction. Further, heparin-DBCO was synthesized and incorporated into the network to leverage the native growth-factor binding ability of heparin. SPAAC was then used to crosslink the polymers using bifunctional PEG-azides to form hydrogel networks with independently tunable shear modulus in the range of interest for soft tissue engineering applications (50 Pa to 2000 Pa). Importantly, the crosslinking was extremely rapid leading to gelation within 1-3 min, allowing for fully three-dimensional cell encapsulation. We encapsulated human embryonic stem cell-derived neural progenitors (NPCs) in RGD peptide-functionalized ECMs, demonstrating excellent suitability of the hydrogels for stem cell culture. Further, NPCs could be differentiated into mature neurons in the click ECMs, leading to potential applications in cell-based therapy for Parkinson’s Disease. Click HA ECMs are thus a versatile platform for in vitro studies of microenvironmental regulation of cell behavior as well as for transplantation of therapeutic cells in vivo.