Augmenting in vitro osteogenesis of a glycine–arginine–glycine–aspartic-conjugated oxidized alginate–gelatin–biphasic calcium phosphate hydrogel composite and in vivo bone biogenesis through stem cell delivery

A functionally modified peptide-conjugated hydrogel system was fabricated with oxidized alginate/gelatin loaded with biphasic calcium phosphate to improve its biocompatibility and functionality. Sodium alginate was treated by controlled oxidation to transform the cis-diol group into an aldehyde group in a controlled manner, which was then conjugated to the amine terminus of glycine–arginine–glycine–aspartic. Oxidized alginate glycine–arginine–glycine–aspartic was then combined with gelatin-loaded biphasic calcium phosphate to form a hydrogel of composite oxidized alginate/gelatin/biphasic calcium phosphate that displayed enhanced human adipose stem cell adhesion, spreading and differentiation. ¹H nuclear magnetic resonance and electron spectroscopy for chemical analysis confirmed that the glycine–arginine–glycine–aspartic was successfully grafted to the oxidized alginate. Co-delivery of glycine–arginine–glycine–aspartic and human adipose stem cell in a hydrogel matrix was studied with the results indicating that hydrogel incorporated modified with glycine–arginine–glycine–aspartic and seeded with human adipose stem cell enhanced osteogenesis in vitro and bone formation in vivo.