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BACKGROUND: Hydroxyapatite has been widely used in the studies on bone materials due to its good histocompatibility and bone conductivity. But pure hydroxyapatite has no antibacterial properties. Therefore, the antibacterial modification of hydroxyapatite is of great importance.OBJECTIVE: To review the research progress of the antibacterial modification of hydroxyapatite. METHODS: A computer-based retrieval of Science Direct online, PubMed, and CNKI databases was performed for the articles published before 2019. The key words were “antibacterial mechanism, hydroxyapatite, silver, gold, copper, cobalt, chitosan, strontium, zinc, gallium, magnesium, selenium, titanium” in English and Chinese, respectively. The irrelevant, repeated and old articles were excluded. RESULTS AND CONCLUSION: There are many ways to modify hydroxyapatite, but the main way is to add metal antibacterial particles. Silver, gold, copper, cobalt, chitosan, strontium, zinc, gallium, magnesium, selenium and titanium can be added into hydroxyapatite to make it have antibacterial activity. There are still some limitations in the research of antibacterial materials: the release curve of antibacterial Ions in hydroxyapatite has not been well regulated. There are few antibacterial materials, let alone used for implants in vivo. More nontoxic substances with good antibacterial properties need to be found. Due to the toxicity of antibacterial Ions, there is no uniform standard for the optimal concentration of each kind of antibacterial ion.
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Objective To construct a two-dimensional (2D) composite membrane and a three-dimensional (3D) biomimetic scaffold by silk fibroin (SF), type I collagen (Col-I) and hydroxyapatite (HA) blends in vitro, so as to study its physicochemical properties, as well as biocompatibility and explore the feasibility of its application in tissue engineering scaffold materials. Methods 2D composite membranes and 3D scaffolds were prepared by blending SF/Col-I/HA at the bottom of cell culture chamber and low temperature 3D printing combined with vacuum freeze drying. The biocompatibility was evaluated by mechanical property testing, scanning electron microscope and Micro-CT to examine the physicochemical properties of the material, and cell proliferation was detected to evaluate its biocompatibility. Results Stable 2D composite membrane and 3D porous structural scaffolds were obtained by blending and low temperature 3D printing. The mechanical properties were consistent. The pore size, water absorption, porosity and elastic modulus were all in accordance with the requirements of constructing tissue engineering bone. The scaffold was a grid-like white cube with good internal pore connectivity; HA was evenly distributed in the composite membrane, and the cells were attached to the composite membrane in a flat shape; the cells were distributed around pore walls of the scaffold. The shape of the shuttle was fusiform, and the growth and proliferation were good. Conclusions The composite membrane and 3D scaffold prepared by SF/Col-I/HA blending system had better pore connectivity and pore structure, which was beneficial to cell and tissue growth and nutrient transport. Its physicochemical properties and biocompatibility could meet the requirements of bone tissue engineering biomaterials.
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10.3969/j.issn.2095-4344.2013.25.002
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10.3969/j.issn.2095-4344.2013.25.001
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10.3969/j.issn.2095-4344.2013.25.003
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10.3969/j.issn.2095-4344.2013.25.004
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BACKGROUND:As a good candidate for bioresorbable bone graft, carbonate apatite monolith can be prepared by sintering procedure;however, sintering can cause carbonate loss and result in a much lower rate of biodegradation compared to the human bone, thereby influencing the formation of new bone. OBJECTIVE:To fabricate low-crystal inity carbonate apatite monolith as bone graft and test its properties. METHODS:Calcium carbonate monolith prepared by carbonation of Ca(OH) 2 monolith was treated in 1 mol/L RESULTS AND CONCLUSION:The calcium carbonate completely transformed into low-crystal inity B-type carbonate apatite after treated for 14 days. Diametral tensile strength of the final product was (10.27±1.08) MPa, which is adequate as a reconstruction material for bone defect. The carbonate content was (4.80±0.50)%, similar to that of the nature bone. The molar Ca/P was 1.63±0.01, indicating the Ca-deficient carbonate apatite is obtained. The present method al ows an easy fabrication of low-crystal inity B-type carbonate apatite block with adequate strength and without sintering process. ammonium dihydrogen phosphate solution at 60 ℃ up to 14 days. Diametral tensile strength was examined for biomechanical properties;X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscope observation and chemical analyses (carbonate, calcium and phosphate content) were also performed for physical and chemical properties.
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BACKGROUND:Adipose-derived stem cells discovered recently are a new kind of adult stem cells, and have a strong multi-differentiation capacity. However, there are rare studies concerning in vivo osteogenic capacity of adipose-derived stem cells. OBJECTIVE:To investigate the effect of adipose-derived stem cells combined with gelatin sponge on repairing bone defects. METHODS:Adipose-derived stem cells from rabbit inguinal fat pads were isolated and cultured, and then induced using an osteogenic medium containing bone morphogenetic protein 2 fol owed by injection of gelatin sponge. Radial defect models of rabbits were prepared. Compound of adipose-derived stem cel s and gelatin sponge was implanted into the lesion side, while gelatin sponge alone was implanted into the contralateral side. Rabbits were kil ed at weeks 6 and 12 after bone defect repair for X-ray examination, CT scan, and hematoxylin-eosin staining. RESULTS AND CONCLUSION:Lane-Sandhu X-ray and Lane-Sandhu histological scores after compound implantation were significantly higher than those after repair with gelatin sponge alone. It indicates that adipose-derived stem cel s combined with gelatin sponge can promote bone defect healing of rabbits, showing an obvious osteogenic capacity in vivo.
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BACKGROUND:As a bone scaffold material,β-tricalcium phosphate has good biocompatibility, osteoinductive, and biomechanical properties. OBJECTIVE:To study the effect of al ogeneic osteoblasts compounded withβ-tricalcium phosphate in repairing rabbit radial defects. METHODS:A total of 45 rabbit radial defect models were made and divided into three groups in random. Experimental group was repaired with the compound of al ogeneic osteoblasts andβ-tricalcium phosphate; control group withβ-tricalcium phosphate;and blank control group with nothing. The new bone formation of each group was observed and assessed by X-ray and histopathological analysis at weeks 4, 8, 16 after implantation for evaluation of the bone repairing effect. RESULTS AND CONCLUSION:With the repair time, the experimental group appeared to complete bone defect repair gradual y. By the end of 16 weeks, the X-ray showed that the bone cal us between the scaffold and the host was completely ossified, and bone defects were completely repaired in the experimental group. Histopathological observation showed continuous cortical bone formed in the defect area, and canal recanalization realized in the experimental group. Additional y, the repair effect in the experimental group was better than that in the control and blank control group at different time points (P<0.01). It is suggested that the al ogenic osteoblasts/β-tricalcium phosphate compound has the better effects on guiding bone regeneration and preventing from nonunion.
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BACKGROUND:Currently, limb salvage therapy has become the standard treatment of malignant bone tumors way, but improper treatments wil result in tumor recurrence, secondary infection, internal fixation or prosthesis loosening. OBJECTIVE:Based on the traditional surgical principle for metastatic bone tumors of the limbs, this study designed a user-friendly, individualized, simplistic pal iative treatment regimen from the actual conditions of patients to observe the reasonability, clinical efficacy and prognosis of bone cement fil ing combined with internal fixation in the treatment of metastatic malignant bone tumors. METHODS:Thirty-one patients with metastatic malignant bone tumors who required salvage treatment were screened from the Department of Orthopedics, the 421 Hospital of Chinese PLA, and their clinical data were retrospectively analyzed. Al the 31 patients were divided into two groups:tumor removal+internal fixation group (non-chemoradiotherapy group, n=11) treated with bone cement fil ing plus plate internal fixation (pal iative treatment);tumor removal+internal fixation+chemoradiotherapy group (chemoradiotherapy group, n=20), treated with radiotherapy before internal fixation plus plate internal fixation with limb salvage. The fol ow-up period was 4-38 months, averagely 18 months. RESULTS AND CONCLUSION:The fol ow-up results showed that in the non-chemoradiotherapy group, al the 11 patients survived, who could live independently and have good motor functions;in the chemoradiotherapy group, 17 of the 20 patients survived and the rest three patients died of tumor metastasis, their poor conditions and complications at 9 and 13 months after internal fixation. In patients undergoing tumor removal+plate internal fixation with limb salvage, the integrated scores for nerve and motor functions were increased by more than level 1. These findings confirm that a simple pal iative therapy of bone cement fil ing and internal fixation without chemoradiotherapy is better for metastatic malignant bone tumors patients who require limb salvage.
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BACKGROUND:The phenomenon of osteoinduction by biomaterials has been proven in animal experiments. OBJECTIVE:To investigate whether the ability of a biomaterial to initiate bone formation in ectopic implantation sites improves the performance of osteoinductive biomaterial as a scaffold for tissue-engineered bone. METHODS:We compared ectopic bone formation by combining autologous adipose-derived stromal cells with an osteoinductive and a nonosteoinductive biphasic calcium phosphate ceramic to create a tissue engineering construction in the muscle of dogs. Al implants were implanted in the back muscle of 10 adult dogs for 8 weeks and 12 weeks, including osteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (osteoinductive complex group), osteoinductive biphasic calcium phosphate ceramic (osteoinductive broup), nonosteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (nonosteoinductive complex group), and nonosteoinductive biphasic calcium phosphate ceramic (nonosteoinductive group). Micro-CT analysis and histomorphometry were performed to evaluate and quantify ectopic bone formation. RESULTS AND CONCLUSION:Ectopic bone formation was visible in the osteoinductive complex group and osteoinductive group, and the former group was superior to the latter one in quality of new bone (P<0.05). However, there was no ectopic bone formation in the other two groups. Micro-CT results were consistent with the histomorphological detection. These findings indicate that osteoinductive biphasic calcium phosphate ceramic, as a kind of bone tissue engineering scaffold material, has a better osteogenic capacity, while adipose-derived mesenchymal stem cells serve as seed cells to promote the ectopic bone formation.
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BACKGROUND:Silk fibroin, chitosan, and nano hydroxyapatite are natural materials, and they al have good biological activity and physical or chemical properties. As tissue engineering materials, they have been already widely used in clinic or research work, but there are some defects in the application of these three kinds of materials. OBJECTIVE:To discuss the preparation and characteristics of silk fibroin/chitosan/nano hydroxyapatite complicated scaffolds which could be used in bone tissue engineering. METHODS:Silk fibroin, chitosan, and nano hydroxyapatite were separately prepared into 2%solution, and then mixed at the ratio of 1:1:0.5, 1:1:1, 1:1:1.5 respectively. The three-dimensional complicated scaffolds were prepared by those mixed liquids through repeated freeze drying and chemical crosslinking technology. Scanning electron microscope was used to detect the pore size of the scaffolds. Porosity, water absorption rate, and hot-water loss rate were determined. Mechanical tester was used to measure the tensile and compressive modulus of dried three-dimensional scaffolds. RESULTS AND CONCLUSION:The silk fibroin/chitosan/nano hydroxyapatite complicated scaffold in the dry state had no special smel , appeared to be a stabilized solid cylinder, and exhibited clear resiliency and flexibility with a touch. With the increased content of nano hydroxyapatite, the porosity, water absorption rate and average pore size of the scaffolds appeared to be decreased, while the hot-water loss rate and compressive strength were increased. The scaffold prepared at 1:1:1 was better for bone tissue engineering, and the average pore size, water absorption rate and hot-water loss rate were 85.67 μm, (135.65±4.56)%and (22.84±1.06)%, respectively, closer to the needs of the bone tissue engineering. Uniform pores were found within the scaffold at 1:1:1, showing the network structure, developed transport among pores, and the network structure was approximately 10μm.
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BACKGROUND:Titanium has been widely used in dental implantation because of its good biocompatibility, mechanical properties and its similar elastic modulus to the bone. OBJECTIVE:To summarize three strategies for surface modification of titanium implants:physical modification, chemical modification and biochemical modification. METHODS:PubMed and CNKI databases were searched for articles published from January 2007 to February 2013, and the key words were“titanium, implant, surface modification, osseointegration”in English and Chinese, respectively. Articles which are closely related to titanium implant surface modification and osseointegration were included, and repetitive articles were removed. RESULTS AND CONCLUSION:After preliminary search, 199 articles were found. According to the inclusion criteria and exclusion criteria, 76 articles were further analyzed. Titanium implant is a bioinert material, and thus the researchers focus on surface modification to activate the titanium implant so as to possess biological function and achieve early osseointegration. Implant surface modification strategies include three perspectives:physical modification, chemical modification and biochemical modification which can shorten the period of implant therapy and achieve early osseointegration and higher binding strength. The future research trend is to combine three strategies and to further explore the molecular basis of mechanism at the interface between implant and organism cel and the tissue in order to use better surface modification technology to fulfil the early and more stable osseointegration between the implant and bone tissue.
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BACKGROUND:The form and structure of antigen-extracted xenogeneic cancel ous bone through series of physical and chemical treatment are similar to human tissue. OBJECTIVE:To detect the biocompatibility of antigen-extracted xenogeneic cancel ous bone matrix prepared by three different ways. METHODS:The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods and hydroxy apatite biological ceramic materials were implanted into the dorsum subcutaneous tissue. Histological observation was done at 4, 8 and 12 weeks after surgery. The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods respectively was used to culture sheep bone marrow mesenchymal stem cells for 7 days. Cel adhesion, growth, proliferation and stroma secretion were observed. RESULTS AND CONCLUSION:At 4 weeks after surgery, a strong inflammatory reaction was detected around materials in four groups. At 12 weeks, the xenogeneic bone materials prepared through physical and physical-chemical combined methods and hydroxy apatite biological ceramic materials internal pore and surrounding tissue inflammation disappeared basical y, with the presence of thimbleful inflammation cells. The material degradation was more than at 8 weeks. The xenogeneic bone materials prepared through chemical methods material internal pore and surrounding tissue inflammation stil existed, suggesting that the xenogeneic bone materials prepared through physical and physical-chemical combined methods exhibited good histocompatibility. A smal amount of orderly osteoblasts existed around hydroxy apatite biological ceramic materials and physical-chemical prepared materials, with a smal amount of bone. These suggested that there was a tendency for ectopic bone formation. The xenogeneic cancel ous bone materials prepared through physical or physical-chemical combined methods have better cytocompatibility. However, scaffold materials prepared through chemical method have poor cytocompatibility and they are not qualified for the safety standards of biological materials.
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BACKGROUND:Through a ful investigation of biodegradable scaffolds, we propose a new self-expanding degradable poly-L-lactide coated endotracheal stent based on the design, production, experimental and clinical applications of nickel titanium memory alloy stent. OBJECTIVE:To design a kind of biodegradable endotracheal stent with poly-L-lactide and hydroxyapatite, and to test its mechanical properties, biocompatibility and biodegradation capacity. METHODS:With the technology of computer aided design, the stents were prepared with poly-L-lactide (Mr RESULTS AND CONCLUSION:The average radial supporting force of the tracheal stent was 7.8 kPa, the percentage of stent surface coverage was less than 20%, the stent expansion rate was≥4%, and the stent longitudinal shortening rate was≤9%, which reached the mechanical requirements for degradable endotracheal stents. After 4-16 weeks, there was no significant inflammatory response. The decline in molecular weight changes and weight loss ratio was higher for in vivo degradation than in vitro degradation at different time (P<0.05). These findings indicate that poly-L-lactide/hydroxyapatite composite stents have good mechanical properties, biocompatibility and biodegradability. 150 000) and hydroxyapatite materials, 20 mm to 26 mm in diameter. The mechanical properties were tested using a universal testing machine. These poly-L-lactide/hydroxyapatite stents were implanted into dog models of tracheal stenosis at an appropriate size. The histopathological changes of the tracheas were observed, and biodegradation property was studied via molecular weight changes and weight loss ratio after 4, 8, 12, 16 weeks.