Repairing Osteochondral Defect of Rabbits with Nano-HA/CS Scaffold Composite with Chondrocyte by Boot-shaped Structure

【Objective】 To observe the condition of constructing the tissue engineered chondral composite constructing by co-culturing the chondrocyte which were induced from bone marrow stem cells(BMSCs) and nano-hydroxyapatite/chitosan scaffold(nano-HA/CS),under a boot-shaped structure after compositing.The effect of the composite on repairing the osteochondral defect of rabbits' knee were observed.【Methods】The technique of combining the in situ hybridization and freeze-drying was taken to fabricate nano-HA/CS scaffold.The cylindrical boot-shaped structure were made of polytetrafluoroethylene.The chondrocyte were induced from BMSCs by cultivating in the chondrogenic differentiation medium.Then they were seeded into the bottom of the nano-HA/CS scaffold whose top was coverd by the boot-shaped structure.The composite was cultivated in the chondrogenic differentiation medium for 2 weeks.The structure of nano-HA/CS scaffold and composite was observed by scanning electron microscope.The osteochondral defects in the epicondyle of femur,which was 4 mm in diameter and 8 mm in depth,were constructed in 30 New Zealand white rabbits.The rabbits were divided into three groups,experimental group(composite induced with boot-shaped structure grafted into the defect),control group(composite induced without boot-shaped structure),and blank group(with no implant).Finally the curative effect of specimens after 4 and 12 weeks were evaluated respectively.【Result】 BMSCs can be induced to chondrocyte after cultivated in the chondrogenic differentiation medium.The nano-HA/CS scaffold with 92% interstice ratio and 125 μm diameter had a good adhesion with chondrocyte.In general,cartilage-like tissue were found in experimental group and control group,while fibrous tissue were found in blank group where the defect was still obvious.The HE staining showed that the cartilage defect was repaired by chondrocyte partly and the bone defect was repaired by osteoblasts partly in the experimental group.There was a crossing area in the cartilage-bone interface.Thus the repairing effect and coupling status of cartilage-bone interface in the experimental group was superior to the control group and blank group obviously.Statistical analysis of gross specimen and chondral histology also showed that the experimental group was superior to the other two groups.【Conclusion】 BMSCs have the chondrogenic potentiality.Nano-HA/CS scaffold has good adhesion with chondrocyte.By co-culturing chondrocyte and Nano-HA/CS under a boot-shaped structure can construct the tissue engineered chondral composite,which was proved to be able to repair osteochondral defect in rabbits.