Preparation of silk fibroin/nano-hydroxypatite composite scaffold and its treatment outcomes in spinal fusion / 中国组织工程研究

ABSTRACT

BACKGROUND:Silk fibroin, as an inorganic mineralization template, can induce hydroxyapatite crystal growth, and combined with nano-hydroxyapatite can simulate the inorganic and organic components of natural bone, which is expected to become the most ideal bone graft material. OBJECTIVE:To prepare the silk fibroin/nano-hydroxyapatite composite material and investigate its treatment outcomes in spinal fusion. METHODS:Silk fibroin/nano-hydroxyapatite composite was synthesized by the co precipitation method with silk fibroin and calcium phosphate as raw materials, to simulate the structure and composition of the bone tissue. The crystal phase composition and microstructure of the composite scaffold were analyzed by X-ray diffraction and transmission electron microscope. Osteoblasts were seeded onto the composite, and the cel adhesion and proliferation were observed under inverted microscope. The lumbar posterolateral spinal fusion models were established in the New Zealand rabbits, fol owed by treated with autologous bone graft (control group) and composite (composite group), respectively. The gross, radiological and histological observations of bone fusion were compared between groups. RESULTS AND CONCLUSION:Silk fibroin/nano-hydroxyapatite composite appeared to be fascicular under electron microscope, the length was 200-500 nm and width was 20-30 nm. And the hydroxyapatite was about 200 nm in length and 50 nm in width. X-ray diffraction showed that the bottom of diffraction peak was wide, and the peak was not sharp. Transmission electron microscope found that cel s adhered wel onto the composite scaffold at 2 days. Scanning electron microscope showed that the polygonal, oval or conical cel s covered most of the composite scaffold holes, presented obvious mitotic phase at 5 days. The third generation of MC3T3-E cel s tended to rise at first 3 days, and then decreased. The fusion site of L5-6 transverse process was strong, and non-bony fusion occurred. At the same time, numerous new bones were visible in the composite group. Hematoxylin-eosin staining showed a large number of cel aggregation, abundant osteoblasts surrounding cartilage, and the bone tissues were in a regular arrangement in the composite group. Moreover, irregular trabecular bone with medul ary cavity was found in the composite material. These results suggest that the silk fibroin/nano-hydroxyapatite composite with the similar structure and composition of natural bone can achieve satisfactory fusion effect in the rabbit lumbar posterolateral fusion.