Patient-specific Scaffolds with a Biomimetic Gradient Environment for Articular Cartilage-Subchondral Bone Regeneration.

Functional articular repair is known to be hampered by tissue degradation, which occurs in the defective local inflammatory environment that is also characterized by disrupted angiogenesis. The advanced fabrication of scaffolds with designed chemical and physical cues, which provide a biomimetic environment for tissue regeneration, holds considerable promise to circumvent the problem and thus allows functional articular repair. Herein, we developed scaffolds with controllable shapes with hydroxybutyl chitosan (HBC) and oxidized chondroitin sulfate (OCS) hydrogels, whose chemical composition was similar to that of the cartilage extracellular matrix (ECM). By optimizing the concentration of OCS, the functional cross-linker, we achieved a hydrogel promoting proliferation, adhesion, and ECM formation of chondrocytes and inhibiting tube formation of endothelial cells. Using a hydration procedure and bioactivation of mesenchymal stem cells (MSCs), we obtained mesoporous silicate-doped calcium phosphate cement (MS/CPC) scaffolds with a bioactive surface similar to that of bones, with improved osteogenesis and vascularization properties. Personalized cartilage-subchondral repair scaffolds with stable combination were successfully fabricated based on the self-cross-linking properties of the Schiff-based HBC/OCS hydrogel and the macroporous structure of MS/CPC scaffolds with the aid of a 3D printing technique. This study proposes a strategy to design individualized tissue repair biomimetic gradient scaffolds. Further assessments of their osteochondral defect repair properties should be performed.