Self-crosslinking and injectable chondroitin sulfate/pullulan hydrogel for cartilage tissue engineering

Abstract Injectable hydrogels derived from natural polysaccharides have great application prospects in cartilage tissue engineering (CTE). In this study, chondroitin sulfate was functionalized with adipic dihydrazide (CS-ADH), and pullulan was oxidized (oxPL). We fabricated a self-crosslink, biodegradable, in situ forming, injectable hydrogel by covalent hydrazone crosslinking of polysaccharides, without using extra cross-linking agents and releasing harmful byproducts under physiological conditions. The gelation time, equilibrium swelling, degradation behavior, network morphology and mechanical properties of CS-ADH/oxPL hydrogels were well manipulated by varying the weight ratio and concentration of CS-ADH and oxPL. In addition, encapsulation of rabbit articular chondrocytes in CS-ADH/oxPL hydrogels was observed after 14 days culture. Live/Dead staining assay demonstrated that the hydrogel system possessed good cytocompatibility. Sulfated glycosaminoglycan (sGAG) contents indicated that the hydrogel system favored cartilaginous extracellular matrix (ECM) deposition. Furthermore, the hydrogel system could maintain the chondrocyte phenotype and enhance chondrogenesis, which was evaluated in terms of their protein and gene expression. These features support that CS-ADH/oxPL hydrogels have a potential as an injectable cell delivery carrier scaffold in CTE.