Construction Of APC/HA/COL/PCL Composite Scaffold And Evaluation Of Its Osteogenic Properties

BackgroundIn clinic, bone defects are very common due to trauma, tumor, infection, surgical debridement and congenital diseases. Bone transplantation is the only method for the repairment of bone defects. However, traditional bone transplantation has some disadvantages. Bone tissue engineering can achieve the purpose of repairing or reconstructing bone, and brings a new choice for the treatment of patients with bone defects. Palygorskite(APC) is a new type of clay mineral containing Na+, Ca2+, Fe3+, and Al3+ with colloidal properties of unique dispersion, high temperature resistance, and salt resistance, it also has high adsorption and decolorization ability, certain plasticity and cohesive force, and good bioactivity and compatibility. Preliminary studies show that APC has the function of bone repairing. ObjectivesThe objectives of this study were to build new composite scaffold material with APC/hydroxyapatite(HA)/collagen(COL)/polycaprolactone(PCL) by synthesizing HA with different calcium(Ca)/phosphorus(P) ratios, and to evaluate its effects on bone repairing so as to provide experimental evidence for its clinical application in the repairment of bone defects.MethodsHA with different Ca/P ratios was prepared by chemical precipitation and microwave irradiation. APC/HA/COL/PCL composite scaffold was prepared by solution perfusion and solvent evaporation and ion leaching methods. Ca/P ratios and compositions of HA were detected by X-ray energy dispersive spectroscopy and Fourier transform infrared spectrometer. The characterization, active ingredients, and hydrophilic and mechanical properties of the composite scaffold were respectively evaluated by scanning electron microscopy, Fourier transform infrared spectrometer, surface contact measuring instrument, and universal testing machine. Tissue compatibility, degradability and osteogenic effects of the composite scaffold were appraised by animal experiments.ResultsHA with different ratios of Ca/P was successfully synthesized by accurately controlling the p H value of the reactants. The mechanical properties, permeability and hydrophilicity of the constructed APC/HA/COL/PCL composite scaffold were significantly enhanced when compared with the composite scaffold only containing APC(P < 0.05). The porosity and swelling ratio of water absorption of the constructed APC/HA/COL/PCL composite scaffold were significantly lower when compared with the composite scaffold without APC(P < 0.05). Animal experiments showed that the constructed scaffold had no host-rejection and immune inflammatory reactions and had good histocompatibility. Micro-CT displayed that the new bone area was the largest in 1.50 group, and there were significant differences in new bone area between 1.50 group and other groups(P < 0.05). Tissue mineral density was the largest in 0.00 group, but there was no significant difference between 0.00 group and 1.50 group(P > 0.05). Animal experiments also showed that all three kinds of composite scaffolds could promote the repairment bone defects, and composite scaffold constructed with calcium-deficient hydroxyapatite and APC showed the best effects. Histological staining showed that the new bone area was significantly higher in 1.50 group than that of the other groups. Immunohistochemical staining(alkaline phosphatase, collagen type â… , collagen type â…¡, and osteopontin) displayed that 1.50 group manifested the best effect on the repairment of bone defects.ConclusionsAPC combined with calcium-deficient HA, bioactive COL, and PCL providing mechanical properties can be constructed to form a bone-repairing composite scaffold similar to the components of natural bone with good bioactivity, histocompatibility and osteoinductivity.