RESUMO
OBJECTIVE: To explore the feasibility of chitosan/allogeneic bone powder composite porous scaffold as scaffold material of bone tissue engineering in repairing bone defect. METHODS: The composite porous scaffolds were prepared with chitosan and decalcified allogeneic bone powder at a ratio of 1 : 5 by vacuum freeze-drying technique. Chitosan scaffold served as control. Ethanol alternative method was used to measure its porosity, and scanning electron microscopy (SEM) to measure pore size. The hole of 3.5 mm in diameter was made on the bilateral femoral condyles of 40 adult Sprague Dawley rats. The composite porous scaffolds and chitosan scaffolds were implanted into the hole of the left femoral condyle (experimental group) and the hole of the right femoral condyle (control group), respectively. At 2, 4, 8, and 12 weeks after implantation, the tissues were harvested for gross observation, histological observation, and immunohistochemical staining. RESULTS: The composite porous scaffold prepared by vacuum freeze-drying technique had yellowish color, and brittle and easily broken texture; pore size was mostly 200-300 µm; and the porosity was 76.8% ± 1.1%, showing no significant difference when compared with the porosity of pure chitosan scaffold (78.4% ± 1.4%) (t = -2.10, P = 0.09). The gross observation and histological observation showed that the defect area was filled with new bone with time, and new bone of the experimental group was significantly more than that of the control group. At 4, 8, and 12 weeks after implantation, the bone forming area of the experimental group was significantly larger than that of the control group (P < 0.05). The immunohistochemical staining results showed that osteoprotegerin (OPG) positive expression was found in the experimental group at different time points, and the positive expression level was significantly higher than that in the control group (P < 0.05). CONCLUSION: Chitosan/allogeneic bone powder composite porous scaffold has suitable porosity and good osteogenic activity, so it is a good material for repairing bone defect, and its bone forming volume and bone formation rate are better than those of pure chitosan scaffold.
