Incorporation of chitosan in biomimetic gelatin/chondroitin-6-sulfate/hyaluronan cryogel for cartilage tissue engineering

We prepare an elastic macroporous gelatin/chondoitin-6-sulfate/hyaluronan (GCH) cryogel scaffold mimic the composition of cartilage extracellular matrix for cartilage tissue engineering. By incorporating chitosan in the cryogel to replace 20% gelatin, a GCH-chitosan cryogel was also synthesized and compared with GCH cryogel for scaffold mechanical properties and chondrocytes response. The GCH-chitosan cryogel has larger pores, higher ultimate strain (stress) and elastic modulus, and lower stress relaxation percentage than the GCH cryogel. Both cryogels show a highly elastic property with a loss tangent around 0.1, but chitosan incorporation increases the storage modulus (elasticity). Chondrocytes proliferate and redifferentiate in cryogels; chitosan diminishes cell proliferation but up-regulates glycosaminoglycans (GAGs) and type II collagen (COL II) secretion. Implantation of a chondrocytes/GCH-chitosan cryogel construct in a full-thickness articular cartilage defect regenerates cartilage with positive stainings for GAGs and COL II and an elastic modulus similar to the native cartilage.