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BACKGROUND: Preliminary study has shown that the composite materials composed of magnesium-based materials and mineralized collagen have a good supporting effect on repairing the critical defects, which can improve the mechanical strength of mineralized collagen and premature collapse during bone healing to some extent. However, magnesium-based metals degrade fast in chloride-containing solutions (including human body fluids or plasma), and the effects of releasing magnesium ions on the proliferation and differentiation of osteoblasts are unknown. OBJECTIVVE: To investigate the effects of magnesium ion combined with mineralized collagen on osteogenic differentiation of mouse preosteoblasts in vitro. METHODS: Mineralized collagen extracts were prepared from complete medium with magnesium ion concentration of 0, 5, 10, and 20 mmol/L. Mouse preosteoblasts were cultured with four mineralized collagen extracts, respectively, which were divided into mineralized collagen group, and 5, 10 and 20 mmol/L Mg2++mineralized collagen groups. The mouse preosteoblasts cultured in complete medium were used as control group. The cell morphology, proliferation, apoptosis, intracellular microfilament actin, and the activity of alkaline phosphatase and expression level of the osteogenic gene Runx2 after osteogenic differentiation were detected. RESULTS AND CONCLUSION: (1) After 24 hours of culture, the cells in the mineralized collagen group, and 5 and 10 mmol/L Mg2++ mineralized collagen groups adhered well, which showed no significant difference from the blank control group, and the elongated spindle cells with many synapses linked to the adjacent cells were observed. The cells in the 20 mmol/L Mg2++mineralized collagen group showed obvious pyknosis. (2) After 1, 3 and 5 days of culture, the cell viability in the 10 mmol/L Mg2++mineralized collagen group was significantly higher than that in the other four groups (P 0.05). The cell viability in the 20 mmol/L Mg2++mineralized collagen group was significantly lower than that in the mineralized collagen group (P < 0.05). (3) After 3 days of culture, DAPI staining showed that 20 mmol/L Mg2++mineralized collagen group had obvious nuclear disintegration, the other four groups had no obvious nuclear disintegration. (4) After 24 hours of culture, phalloidin staining showed that except the blank control and 20 mmol/L Mg2++mineralized collagen groups, the other three groups showed completely extended cell structure, and clear actin microfilaments, especially the 10 mmol/L Mg2++mineralized collagen group. (5) After 7 days of osteogenic differentiation, except for 20 mmol/L Mg2++mineralized collagen group, the activity of alkaline phosphatase and the expression level of Runx2 gene in the other three groups were significantly higher than those in the blank control group (P < 0.05), and those in the 10 mmol/L Mg2++mineralized collagen group was significantly higher than those in the 5 mmol/L Mg2++mineralized collagen and mineralized collagen groups (P < 0.05). (6) These results suggest that the combination of magnesium ion with mineralized collagen should be applied with appropriate concentration range of magnesium ion (≤ 10 mmol/L).
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BACKGROUND: A mineralized collagen composite, i.e. nano-hydroxyapatite/collagen (nHAC) has biomimetic three-dimensional structure and good bioactive properties. As a bone tissue engineering material, it is widely used in bone defect repair. A newly designed P17-bone morphogenetic protein-2 (P17-BMP2) has good biocompatibility and osteogenic capacity. Therefore, the composite scaffold material was prepared by combining the new P17-BMP-2 and nHAC, which might be used for the enhancement of osteogenic capacity in the treatment of bone defects. OBJECTIVE: To investigate the bioactivity of the P17-BMP-2/nHAC composite. METHODS: Rabbit bone marrow mesenchymal stem cells were seed on the P17-BMP-2/nHAC composite and nHAC. After 3 and 7 days of culture, the relative expression level of alkaline phosphatase was detected by RT-PCR. The subcutaneous implantation of P17-BMP-2/nHAC (experimental group) and nHAC (control group) into Sprague-Dawley rats was performed. Masson staining was performed for histological analysis at 12 and 35 days of implantation. P17-BMP-2/nHAC (experimental group) and nHAC (control group) were implanted into the white rabbit mandibular box-shaped bone defect, respectively. At 5 and 15 weeks, gross observation and X-ray were performed. The study was approved by the Medical Ethics Committee of China Medical University School & Hospital of Stomatology. RESULTS AND CONCLUSION: (1) The relative expression level of alkaline phosphatase in the P17-BMP-2/nHAC group was significantly higher than that in the nHAC group (P < 0.05). (2) The result of subcutaneous implantation showed that the acute inflammatory response initiated by the P17-BMP-2/nHAC or nHAC was not found. More activated fibroblasts growing into the implants could be found on the sections of P17-BMP-2/nHAC compared to that of nHAC at 35 days after implantation. (3) In the bone defect repair test, gross observation showed that both materials held good defect repair ability, the defect area began to reduce at 5 weeks after implantation, and the defect surface became flat at 15 weeks after implantation. X-ray examination showed that compared with the control group, the defect area was more significantly reduced in the experimental group. (4) These results indicate that P17-BMP-2/nHAC composite scaffold has higher bioactivity and a stronger ability to repair bone defect.
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Objective To evaluate the clinical outcome associated with the core decompression in combination with the nano-hydroxyapatite/collagen composite rod combined with decalcified bone matrix in a consecutive series of patients with osteonecrosis of femoral head,especially the prevention of collapse of femoral head and its predisposing factors.Methods From August,2012 to May,2013,46 pationts (50 hips) who had undergone core decompression in combination with nano-hydroxyapatite/collagen composite rod insertion in corporated with decalcified bone matrix in our hospital were involved in this study.Postoperative care consisted of prophylactic intravenous antibiotic and anticoagulation therapy.Patients were instructed to be non-weight-bearing for 3 weeks,to partial weight-bear for the next 3 weeks,and to weight bear as tolerated thereafter.All patients were evaluated both clinically and radiographically.The primary clinical outcome of this study was functional improvement assessed with the Harris hip score.Serial radiograms of the pelvis were taken at 1,3,6,12 months post-operatively to analyze the process of osteonecrosis.Results All patients followed up for 12 months,no one suffer complications.The mean Harris score pre-operation was 65.6 ± 10.6,post-operation score was 87.5 ± 15.3,with a mean improvement of 21.8 ± 13.2 (P ＜ 0.05).According to Harris hip score system,excellent for 30 hips,good for 14 hips,fair for 2 hip and poor for 4 hips.Refer to the Kaplan-Meier survivorship curve,the success rate at 12 months post-operatively was 92％.Radiological changes coincided with clinical changes.Conclusion Core decompressionin combination with nano-hydroxyapatite/ collagen composite rod insertion in corporated with decalcified bone matrix provided a minimally invasive surgical treatment option to treat early stage osteonecrotic hips(stage Ⅰ and Ⅱ) and to prevent femoral heads from collapsing,with clinical outcomes and success rates priorto other commonly used surgical procedures.
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Objective:To study the bone-conductivity and absorbability of nano-hydroxyapatite/collagen(nHAC) composite implanted under the calvarial periosteum in rabbits.Methods:24 nHAC samples and 24 HA samples were prepaired in the shape of round disk with the diameter of 8 mm and thickness of 3 mm.nHAC samples were implanted under calvarial periosteum on the left side and HA samples on the right of 24 rabbits.The bone-conductivity and absorbability of the samples were examined by new bone height measuring and residual implant materia measuring 2,4,8 and 12 weeks after operation. Results:2,4,8 and 12 weeks after implantation new bone height(mm) in nHAC group was 0.54?0.09,0.72?0.12,1.83?0.14 and 2.63?0.07,that in HA group 0.13?0.11,0.31?0.12,1.23?0.05 and 1.75?0.14,respectively(P