Repair of radius bone defect with the nano-hydroxyapatite/collagen/calcium alginate / 中国医学科学院学报

<p><b>OBJECTIVE</b>To explore the osteogenic potential of the nano-hydroxyapatite/collagen/calcium alginate composite implanted in animals.</p><p><b>METHODS</b>Eighteen 3-month-old New Zealand white rabbits were adopted to prepare 15 mm segmental defect model at the middle part of radius. Rabbit models were randomly divided into experimental group and blank control group. Nano-hydroxyapatite/collagen/calcium alginate was implanted into the defects of experimental group. Four, 8, and 12 weeks after operation, all specimens were examined by X-ray and histological methods.</p><p><b>RESULTS</b>All the 18 rabbit models entered the final analysis. X-ray showed that osteotylus was seen in the whole defect area in the experimental group 12 weeks after operation, during which osteogenesis was more obvious than in weeks 4 and 8 and the bridge grafting of defect area was obviously visible. In the blank control group, osteotylus was only observed at the two ends of the defects, and no osteogenesis was found in the central part of the defect area. Histological examination showed that new osteoid formation was seen in internal porous zone in the experimental group in weeks 4 and 8; in week 12, more woven bone-like tissues were visible and trabecular-like structure was formed.</p><p><b>CONCLUSION</b>The nano-hydroxyapatite/ collagen/calcium alginate has good osteogenic potential.</p>

Preparation and characterization of a new injectable bone substitute-carrageenan/nano-hydroxyapatite/collagen / 中国医学科学院学报

<p><b>OBJECTIVE</b>To develop a new injectable biomaterial carrageenan/nano-hydroxyapatite/collagen (nHAC/Carr) for bone surgery and characterize it.</p><p><b>METHODS</b>nHAC/Carr was developed by filling carrageenan with nano-hydroxyapatite/collagen (nHAC) granules.</p><p><b>RESULTS</b>It was found that nHAC/Carr had similar X-ray diffraction patterns with that of nHAC. Fourier transform infrared spectroscopy showed that carrageenan did not change its structure in nHAC/Carr. The rheological behavior of nHAC/Carr was the same as carrageenan. The scanning electron microscopy and porosity analysis showed that nHAC/Carr had porous structure and its porosity was about 90%.</p><p><b>CONCLUSION</b>The biomaterial nHAC/Carr may be used as an injectable bone substitute.</p>

Nano-hydroxyapatite/collagen composite for bone repair / 中国医学科学院学报

<p><b>OBJECTIVE</b>To develop nano-hydroxyapatite/collagen (NHAC) composite and test its ability in bone repairing.</p><p><b>METHODS</b>NHAC composite was developed by biomimetic method.</p><p><b>RESULTS</b>The composite showed some features of natural bone in both composition and microstructure. The minerals could contribute to 50% by weight of the composites in sheet form. The inorganic phase in the composite was carbonate-substituted hydroxyapatite (HA) with low crystallinity and nanometer size. HA precipitates were uniformly distributed on the type I collagen matrix without preferential orientation. The composite exhibited an isotropic mechanical behavior. However, the resistance of the composite to localized pressure could reach the lower limit of that of femur compacta. The tissue response to the NHAC composite implanted in marrow cavity was investigated. Knoop micro-hardness test was performed to compare the mechanical behavior of the composite and bone. At the interface of the implant and marrow tissue, solution-mediated dissolution and macrophage-mediated resorption led to the degradation of the composite, followed by interfacial bone formation by osteoblasts. The process of implant degradation and bone substitution was reminiscent of bone remodeling.</p><p><b>CONCLUSION</b>The composite can be incorporated into bone metabolism instead of being a permanent implant.</p>