Application Of Chondroitin Sulfate In Cartilage Tissue Engineering

Background:There are three types of articular cartilage defects:partial-thickness, full-thickness and osteochondral defects. Currently, several surgical methods have been employed for the treatment of cartilage defects, including microfracture, osteochondral grafts and prosthetic joint replacement, etc. Tissue engineering is a new integrated discipline, covering biology, medicine, materials science and engineering, etc. and is proved as a promising approach of tissue repair. Chondroitin sulphate (CS) is a glycosaminoglycan (GAG) present in the natural cartilage extracellular matrix (ECM) and has many biological properties. In this study, we designed two scaffolds based on chondroitin sulfate for the repair of articular cartilage defects, and explored new application of chondroitin sulfate in cartilage tissue engineering. This study includes two parts:(1) Investigation of the repair of full-thickness cartilage defects with silk-CS scaffold;(2) Investigation of the repair of partial-thickness cartilage defects with CS-dopamine coating. Part I Silk-CS scaffold for the repair of full-thickness cartilage defectsObjective:In this part, we investigated the effects of the silk-CS scaffold on full-thickness cartilage defects regeneration.Methods:Silk and silk-CS scaffolds were fabricated. The microstructure, chondroitin sulfate content and mechanical properties were characterized. Human chondrocytes were seeded in silk and silk-CS scaffolds, and cell adhesion, proliferation and migration were evaluated. The anti-inflammatory activity of silk-CS scaffold was assessed by real time RT-PCR after IL-1β stimulation. Full-thickness cartilage defects were made in the New Zealand rabbits. At6and12weeks after surgery, the rabbits were sacrificed. Histology was used to verify the repair capacity of implants in vivo.Results:Compared with silk scaffold, silk-CS scaffold exhibits better mechanical properties, stronger ability to promote cell migration and higher anti-inflammatory activity. The rabbit joint cartilage showed more neo-tissue formation in the silk-CS scaffold group.Conclusion:Silk-CS scaffold was favorable for the full-thickness cartilage defects regeneration.Part Ⅱ CS-dopamine coating for the surface modification of cartilageObjective:In this part, we investigated the physiological functions of CS-dopamine (CS-D) coating to discuss the feasibility of applying to partial-thickness cartilage defects regeneration.Methods:Synthesis of CS-D complex, and using’H-NMR spectrum to characterize its structure. The CS-D coating on cartilage surface was prepared, and the morphology of the deposited coating was observed in term of atomic force microscope (AFM). Cell culture was performed with human chondrocytes, and the cytotoxicity, cell proliferation and cell adhesion were assessed.Results:The surface structure and roughness of CS-D coated cartilage have no significant change. The CS-D coating has no cytotoxicity, can promote the proliferation of chondrocytes and enhance the adhesion of chondrocytes on cartilage surface.Conclusion:CS-D is a promising material for cartilage tissue engineering with excellent Cytocompatibility and bioactivities.