Glycan-Functionalized Collagen Hydrogels Modulate the Glycoenvironment of a Neuronal Primary Culture

Glycans play a central role in the development and homeostasis of the central nervous system (CNS), so changes in the glycosylation profile of the cell surface and extracellular matrix (ECM) components are evident in CNS disorders. Regenerative medicine-based strategies using biomaterial platforms are being increasingly used to target these diseases and to study the glyco-signature of the physiological and pathological conditions, particularly through the use of biomaterials able to recapitulate natural components and physical organization of the ECM. Collagen hydrogels have shown potential as a vehicle for the delivery of cells into the brain, and their therapeutic effect can be expanded by functionalizing them to address the glycosylation patterns altered with specific brain disorders. The goal of this study is to develop and optimize a glycan-functionalized tridimensional collagen-based hydrogel that will make contact with and modulate the differentiation of a primary neuronal culture. The developed system would provide more information on how a glyco-engineered material can influence the native glyco-signature profile during the process of cell differentiation by a differential modulation of glycan expression at the tissue level. To this purpose, collagen polymers underwent one step reductive amination with maltose (Glc(α1-4)α-Glc) and lactose (Gal(β1-4)β-Glc) so that the pyranosidic structure of the reducing sugar could be sacrificed (acting as a linker) and the α-Glc and β-Gal residues exposed, respectively. The glycoconjugate biopolymers were used to formulate hydrogels that were chemically and biologically characterized, and the glyco-signature profile of a neuronal culture after hydrogel treatment was analyzed by lectin staining. The hydrogel conjugated with glucose limited the astrocytic proliferation for up to 2 weeks and promoted the increase in sialylation while decreasing fucosylation by 2-fold. These results indicate the differential influence of glycan residues present in the matrix on cellular sugar expression and thus have potential to enhance cell delivery systems in the central nervous system.