Biocompatibility of coralline hydroxyapatite/bone morphogenic protein composite for bone tissue engineering / 中国组织工程研究

ABSTRACT

BACKGROUND: Besides good biocompatibility, ideal scaffold for bone tissue engineering should possess the characters of promoting cell proliferation and differentiation inducing the regeneration of bone tissue. However, the osteogenetic ability is limited when the materials of scaffold is used alone.OBJECTIVE: To observe the biocompatibility of coralline hydroxyapafite (CHA)/bone morphogenic protein (BMP) composite and osteoblasts.DESIGN: A comparative observation.SETTING: Department of Orthopaedics, Guangzhou General Hospital of Guangzhou Military Area Command of Chinese PLA.MATERIALS: Composite of CHA/BMP (CCHA) and CHA were cut into blocks of 4 mm×4 mm×3 mm and 10 mm×10 mm ×3 mm respectively, immersed in complete medium for 4 days after autoclaving.HETHODS: The experiments were carried out in the Central Laboratory of the Guangzhou General Hospital of Military Area Command of Chinese PLA from March to August in 2005. ① The bone marrow of New Zealand rabbits were extracted to culture osteoblasts. ② The osteoblasts were co-cultured with CCHA (CCHA group) and CHA (CHA group) respectively, and the blank control group was untouched. ③ The proliferative indexof osteoblasts and activity of alkaline phosphatase were measured at 2, 4, 6 and 8 days after co-cultureMAIN OUTCOME MEASURES: ① Results of osteoblasts observed under phase contrast microscope;② Results of CCHA material observed under scanning electron microscope; ③ Activity of alkaline phosphatase; ④ Proliferative index of osteoblasts.RESULTS: ① Osteobtasts observed under phase contrast microscope: The cell appearance was fusiform, oblate and multi-angles with processes of various number and size, and the cells connected with each other by the processes. ② CCHA observed under scanning electron microscope: The CCHA surfacewas granule-like with micropores. The osteoblasts attached to the surface of the materials and grew in monolayer at first, then overlapped as the cells further differentiation and proliferation High-density granules appeared around the cells,most of them tended to a certain direction, and finally formed bone nod as the crystals of calcium salt increased. The cells were embedded in matrixes. ③ Activities of alkaline phosphatase: The activities of alkaline phosphatase [absorbance (A) value] at 2, 4 6 and 8 days after co-culture in the CCHA group were significantly higher than those in the CHA group and blank control group (4 days: 101.6±7.7, 93.7±6.8, 94.4±5.0; 8 days: 120.1±8.2, 108.3±8.8, 110.4±7.5;P ＜ 0.01 or 0.05＝, and there was no obvious difference between the CHA group and blank control group. ④ Proliferative index: The proliferative indexes were increased as the culture time prolonged in the groups, but there was no obvious difference CONCLUSION: The inside of CHA is coral-like with many micropores, cells can well attach to its surface, and has good biocompatibility. Besides, the combined bone morphogenesis protein can obviously enhance the activity of alkaline phosphatase, which may play a certain role in bone induction.