Development and potential of a biomimetic chitosan/type Ⅱ collagen scaffold for cartilage tissue engineering

Background Damaged articular cartilage has very limited capacity for spontaneous healing. Tissueengineering provides a newhope for functional cartilage repair.Creation of an appropriate cell carrier is one ofthe critical steps for successful tissue engineering.With the supposition thata biomimetic constructmightpromiseto generate better effects, we developed a novel composite scaffold and investigated its potential for cartilagetissue engineering.Methods Chitosan of88% deacetylation was prepared via a modified base reaction procedure.Afreeze-dryingprocess was employed to fabricate a three-dimensional composite scaffold consisting of chitosan and typeⅡcollagen. The scaffold was treated with 1-ethyl-3-( 3-dimethylaminopropyl ) carbodiimide and N-hydroxysuccinimide.Ultrastructure and tensile strength of the matrix were carried out to assess its physico-chemical properties.After subcutaneous implantation in rabbits, itsin vivobiocompatibility and degradability ofthe scaffold were determined.Its capacity to sustain chondrocyte growth and biosynthesis was evaluated throughcell-scaffold co-culturein vitro.Results The fabricated composite matrix was porous and sponge-like with interconnected pores measuring from100 -250μm in diameter.After cross-linking, the scaffold displayed enhanced tensile strength.Subcutaneousimplantation results indicated the composite matrix was biocompatible and biodegradable.In introcell-scaffoldculture showed the scaffold sustained chondrocyte proliferation and differentiation, and maintained the sphericchondrocytic phenotype.As indicated by immunohistochemical staining, the chondrocytes synthesized typeⅡcollagen.Conclusions Chitosan and typeⅡ collagen can be well blended and developed into a porous 3-D biomimeticmatrix.Results of physico-chemical and biological tests suggest the composite matrix satisfies the constraintsspecified for a tissue-engineered construct and may be used as a chondrocyte carrier for cartilage tissueengineering.