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    22 July 2013, Volume 17 Issue 29 Previous Issue    Next Issue
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    Ectopic bone formation in adipose-derived mesenchymal stem cell-seeded osteoinductive calcium phosphate scaffolds
    Yao Jin-feng, Zhang Xiao-wei, Zhou Qi, Zheng Cang-shang, Liang Zhi-gang, Bao Chong-yun
    2013, 17 (29):  5261-5268.  doi: 10.3969/j.issn.2095-4344.2013.29.001
    Abstract ( 264 )   PDF (2574KB) ( 641 )   Save

    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. All 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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    Silk fibroin/chitosan/nano hydroxyapatite complicated scaffolds for bone tissue engineering
    Ye Peng, Tian Ren-yuan, Huang Wen-liang, Ma Li-kun, Deng Jiang
    2013, 17 (29):  5269-5274.  doi: 10.3969/j.issn.2095-4344.2013.29.002
    Abstract ( 505 )   PDF (2292KB) ( 518 )   Save

    BACKGROUND: Silk fibroin, chitosan, and nano hydroxyapatite are natural materials, and they all 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 smell, 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 10 μm.

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    Comparison of the biocompatibility of three kinds of antigen-extracted xenogeneic cancellous bone matrices
    Yin Xiao-peng, Xu Hui-fen, He Hui-yu
    2013, 17 (29):  5275-5281.  doi: 10.3969/j.issn.2095-4344.2013.29.003
    Abstract ( 356 )   PDF (2207KB) ( 614 )   Save

    BACKGROUND: The form and structure of antigen-extracted xenogeneic cancellous bone through series of physical and chemical treatment are similar to human tissue.
    OBJECTIVE: To detect the biocompatibility of antigen-extracted xenogeneic cancellous bone matrix prepared by three different ways.
    METHODS: The antigen-extracted xenogeneic cancellous 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 cancellous 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. Cell 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 basically, 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 still existed, suggesting that the xenogeneic bone materials prepared through physical and physical-chemical combined methods exhibited good histocompatibility. A small amount of orderly osteoblasts existed around hydroxy apatite biological ceramic materials and physical-chemical prepared materials, with a small amount of bone. These suggested that there was a tendency for ectopic bone formation. The xenogeneic cancellous 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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    Chondrocyte differentiation of dog bone marrow mesenchymal stem cells co-cultured with Bio-gide collagen membrane in vitro
    Xie Hui, Yang Fei, Zhao De-wei, Wang Ben-jie, Cui Da-ping, Wang Wei, Huang Shi-bo
    2013, 17 (29):  5282-5289.  doi: 10.3969/j.issn.2095-4344.2013.29.004
    Abstract ( 401 )   PDF (2571KB) ( 658 )   Save

    BACKGROUND: Seed cells and scaffold are two key factors for cartilage defects after osteonecrosis of femoral head using tissue-engineered method.
    OBJECTIVE: To explore the feasibility of Bio-gide collagen membrane combined with dog bone marrow mesenchymal stem cells into chondrocytes.
    METHODS: Bone marrow mesenchymal stem cells were isolated from beagle dogs by whole bone marrow blood centrifugation method and adherence screening method in vitro and cultured. Morphological changes in cells were observed, and identification was done using cell surface antigens. Bone marrow mesenchymal stem cells of passage 3 were induced by chondrocyte induction medium to differentiate into chondrocytes (experimental group). Cells cultured in normal medium were considered as control group. 3-(4, 5-Dimethylthiazol-2-yl) 2, 5-diphenyl tetrazolium bromide assay was used to measure growth curve of chondrocytes. Cells underwent type Ⅱ collagen immunohistochemistry and toluidine blue staining. The coculture of bone marrow mesenchymal stem cells at passage 3 and Bio-gide collagen membrane were observed under an inverted phase contrast microscope and scanning electron microscope.
    RESULTS AND CONCLUSION: Bone marrow mesenchymal stem cells with high purity and high viability were obtained by whole bone marrow blood centrifugation method and adherence screening method. Cells grew well  
    and had strong amplified ability, and successfully differentiated into chondrocytes. Numerous bone marrow mesenchymal stem cells adhered on the Bio-gide collagen membrane, showing a tendency of multi-layer growth. Cells and Bio-gide collagen membrane seem to blend into an integrant part. Cell processes appeared and connected each other and gradually wrapped the Bio-gide collagen membrane, with the presence of obvious cell matrix secretion. These results suggested that bone marrow mesenchymal stem cells can grow and differentiate into chondrocytes on the Bio-gide collagen membrane.

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    Periodontal ligament cells from miniature swine grow on a hydroxyapatite scaffold
    Ma Lu-ping, Zhong Liang-jun, Zhang Yuan-ming, Zhang Yuan, Zhang Peng-tao
    2013, 17 (29):  5290-5295.  doi: 10.3969/j.issn.2095-4344.2013.29.005
    Abstract ( 332 )   PDF (2018KB) ( 351 )   Save

    BACKGROUND: Periodontal tissue engineering technology provides new ideas and new ways for periodontitis-induced bone defect repair.
    OBJECTIVE: To develop a culture model for the periodontal ligament cells of miniature swine, which was constructed with hydroxyapatite, to investigate the biocompatibility with hydroxyapatite.
    METHODS: Periodontal ligament cells from miniature swine were harvested by using tissue explant method. Immunofluorescence was used to detect the expression of stromal cell antigen 1 in the periodontal ligament cells of miniature swine. The third passage cells were co-cultured with a three-dimension hydroxyapatite scaffold, and the biological characteristics of the cells were observed under a scanning electron microscope at days 1, 3, 7 of co-culture.
    RESULTS AND CONCLUSION: The pirmary miniature swine periodontal ligament cells grew well, and they were positive for stromal cell antigen 1. Under the scanning electron microscope, the periodontal ligament cells of miniature swine grew well on the hydroxyapatite scaffold at days 1, 3, 7 of co-culture. These prove that the miniature swine periodontal ligament cells, which can be separated using tissue explant method and cultured successfully in vitro, can grow well on the hydroxyapatite scaffold.

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    Zinc ions improve the stability of titanium implants under the condition of osteoporosis
    Lin Wei, Li Xu-dong, Tang Kuang-yun, Hu Jing
    2013, 17 (29):  5296-5302.  doi: 10.3969/j.issn.2095-4344.2013.29.006
    Abstract ( 367 )   PDF (2136KB) ( 477 )   Save

    BACKGROUND: Zinc can improve bone reaction to titanium implants through regulation of osteoblast activity under the condition of osteoporosis.
    OBJECTIVE: To study the zinc ions effect on improving the stability of titanium implants under the condition of osteoporosis.
    METHODS: After removal of the ovary, 28 female Sprague-Dawley rats presented with osteoporosis symptoms for 12 weeks and then, they were randomly divided into two groups. Two kinds of titanium implants with (experimental group) or without zinc (control group) were inserted into the bilateral femoral metaphysis longitudinally in the ovariectomized rats, separately. Three rats were selected from each group for double fluorescence labeling examination. Mineral apposition rate was calculated at postoperatively 6 weeks. Another four rats were selected from each group for histomorphometry analysis at postoperatively 12 weeks. Biomechanical test was in the remaining rats in the two groups to calculate the maximum push-out force and maximum shear force at 12 weeks postoperatively.
    RESULTS AND CONCLUSION: The double fluorescence labeling examination revealed that the mineral apposition rate was improved in the experimental group as compared with the control group (P < 0.05). New bone formation occurred in the two groups. However, larger new bone amount, higher bone area ratio and bone-to-implant contact were detected in the experimental group (P < 0.05 or P < 0.01). The maximum push-out force and maximum shear force were also superior in the experimental group to the control group (P < 0.05 or P < 0.01). These findings indicate that zinc ions are capable of promoting bone formation and improving implant fixation in ovariectomized rats.

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    Efficiency of resin infiltration versus fluride varnish for treatment of post-orthodontic white spot lesions
    Wang Lu, Jian Jie, Lu Hui-fang
    2013, 17 (29):  5303-5308.  doi: 10.3969/j.issn.2095-4344.2013.29.007
    Abstract ( 494 )   PDF (729KB) ( 798 )   Save

    BACKGROUND: White spot lesions caused by enamel demineralization are a common side effect of orthodontic treatment. Resin infiltration treatment for white spot lesions has obtained favorable effects, but there is no report on the difference between resin infiltration and fluoride varnish treatment for post-orthodontic white spot lesions.
    OBJECTIVE: To compare the efficiency of resin infiltration and fluride varnish for treatment of post-orthodontic white spot lesions.
    METHODS: Twenty-nine patients with post-orthodontic white spot lesions were randomly divided into two groups: one group accepted the resin infiltration treatment and the other group accepted fluoride varnish treatment. Frontal intraoral photos before treatment and 6 months after treatment were collected for study. The difference in efficiency of resin infiltration and fluride varnish for treatment of post-orthodontic white spot lesion was analyzed and evaluated by both dentists and college students who were not engaged in oral medicine.
    RESULTS AND CONCLUSION: Except one patient treated with fluride varnish, all the patients completed the referral on schedule. There was significant improvement in the two groups after treatment (P < 0.05). Resin infiltration treatment was better than fluoride varnish treatment in post-orthodontic white spot lesions. Thus, resin infiltration that requires fewer referrals and has better effects is an ideal therapy for post-orthodontic white spot lesions.

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    Glass fiber post versus metal post in the restoration of endodontically treated teeth
    Chang Zhi-ming
    2013, 17 (29):  5309-5315.  doi: 10.3969/j.issn.2095-4344.2013.29.008
    Abstract ( 922 )   PDF (664KB) ( 652 )   Save

    BACKGROUND: The post and core system for residual roots and crowns can achieve satisfactory effects, when filling restoration, full crowns or inlay has poor effects.
    OBJECTIVE: To evaluate the clinical use of glass fiber post and metal post in the restoration of endodontically treated teeth.
    METHODS: A total of 106 patients with 160 endodontically treated teeth were selected and restored with glass fiber post (n=80 teeth) and metal post (n=80 teeth) followed by porcelain-fused-mental crown. The restorations were evaluated clinically for 9 to 33 months.
    RESULTS AND CONCLUSION: Glass fiber post treatment for 78 teeth was effective and that for two teeth were failed, with a successful rate of 98%. Metal post restoration was effective in 71 teeth and failed in nine teeth including one tooth of crown fracture, four of root fracture and four of post loss, with a successful rate of 89%. There was statistically significant difference between two groups (P < 0.05). Glass fiber post is better in convenient handling and good color and reduced probability leading to root broken for dental restoration compared with metal post.

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    Biocompatibility of olfactory ensheathing cells and poly-L-lactic acid reinforced by chitosan in vitro
    Li Wei-dong, Cui Zhi-ming, Xu Guan-hua, Fan Jian-bo, Bao Guo-feng, Sun Yu-yu, Wang Ling-ling
    2013, 17 (29):  5316-5322.  doi: 10.3969/j.issn.2095-4344.2013.29.009
    Abstract ( 312 )   PDF (2124KB) ( 418 )   Save

    BACKGROUND: Previous studies have shown that composite scaffold of chitosan and poly-L-lactic acid has good biocompatibility with some cells.
    OBJECTIVE: To study the biocompatibility of poly-L-lactic acid reinforced by chitosan and olfactory ensheathing cells.
    METHODS: In experimental group, olfactory ensheathing cells from Sprague-Dawley rats aged 1-3 days were incubated onto chitosan-reinforced poly-L-lactic acid film. And in control group, olfactory ensheathing cells were co-cultured with poly-L-lysine. The proliferative ability of olfactory ensheathing cells was detected and the cells were observed with immunofluorescence histochemical staining at 1, 3, 5, 7 days after culture.
    RESULTS AND CONCLUSION: Olfactory ensheathing cells could survive on the chitosan-reinforced poly-L-lactic acid film, and the cytotoxic grade was Ⅰ. Morphology of the cells in the experimental group was round or oval, with little processes and the cells aggregated into groups. One day after implantation, the periphery cells of the mass extended short projections and gradually spread outward; 3 days after implantation, the cells spread and most of the cells generated projections, most of which were bipolar or tri-polar; 5 days after implantation, cell processes significantly extended, most cells were bipolar and tri-polar cells, while some were oval cells and irregular triangular cells; 7 days after implantation, the cell density increased, and cell processes extended. Cell morphology of the control group had similar characteristics as the experimental group. There was no obvious difference between the control and the experimental group in number, perimeter or area of the cells (P > 0.05). It showed that chitosan-reinforced poly-L-lactic acid had good biocompatibility with olfactory ensheathing cells.

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    In vitro establishment of a three-dimensional hepatocyte culture system using collagen hydrogel as scaffolds
    Wang Min, Lan Ya, Hu Hao, Shi Yong-quan, Han Ying, Zhou Xin-min
    2013, 17 (29):  5323-5330.  doi: 10.3969/j.issn.2095-4344.2013.29.010
    Abstract ( 727 )   PDF (2155KB) ( 898 )   Save

    BACKGROUND: Rapid loss of liver-specific functions of the cultured hepatocytes limits the development of hepatocyte-based therapies.
    OBJECTIVE: To establish a three-dimensional culture system based on collagen hydrogel that enables to enhance liver-specific functions for a long period during culture of hepatocytes.
    METHODS: Hepatocytes were isolated from Sprague-Dawley rats and then encapsulated into liquid type Ⅰcollagen solution that was premixed with hepatocyte growth factor and Dulbecco's modified Eagle’s medium to create hepatocyte/collagen hydrogel compounds. The compounds were inoculated into a 96-well plate. After gelation, culture medium was added. Light microscope, hematoxylin-eosin staining and transmission electron microscopy were used to examine the morphological characteristics and ultrastructure of the cultured hepatocytes. The cell supernatant was collected and tested for albumin secretion and urea synthesis. Periodic acid-schiff staining, immunofluorescence staining and quantitative real-time PCR were also used to further clarify liver-specific phenotype or function of the hepatocytes.
    RESULTS AND CONCLUSION: (1) Light microscope revealed that hepatocytes were round shape and distributed uniformly in collagen hydrogel. The three-dimensional hepatocyte culture system exhibited similarities to liver-like structure and tight junction were formed between hepatocytes after 14 days of culture. (2) Within the three-dimensional culture system, hepatocytes remained positive for periodic acid-schiff staining, albumin and hepatocyte nuclear factor-4α positive after 14-day culture, which provided the convincing evidence of highly differentiated primary hepatocytes with functions of glycogen and albumin synthesis. (3) The albumin and urea productions in the three-dimensional culture system had a significantly higher level than in the two-dimensional culture, and could remain at a high level at least for 15 days. (4) The expression levels of hepatocyte-specific genes including Albumin, HNF-4α, Claudin-3, CYP1A1, CYP3A1 and G6P were significantly improved in the three-dimensional culture as compared with the two-dimensional culture. The collagen hydrogel based three-dimensional culture system provides a valuable model to enhance the hepatocyte functional maintenance and lay the foundation for the development of hepatocyte-based therapy for liver disease.

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    Biological characteristics of glucose-responsive microcapsules carrying beta-TC3 cells
    Zhang Shao-min, Wu Zhong-ming, Yu De-min
    2013, 17 (29):  5331-5336.  doi: 10.3969/j.issn.2095-4344.2013.29.011
    Abstract ( 320 )   PDF (2278KB) ( 561 )   Save

    BACKGROUND: To prepare glucose-responsive microcapsules which can control insulin release as changing the glucose concentration in the medium is of great significance to control the occurrence and development of diabetes mellitus.
    OBJECTIVE: To study the performance of glucose-responsive alginate/modified-chitosan/alginate microcapsules carrying β-TC3 cells.
    METHODS: Glucose-responsive alginate/modified-chitosan/alginate microcapsules were prepared by layer-by-layer self-assembly method to evaluate the performance. And the glucose-responsive microcapsules carrying β-TC3 cells were prepared to observe the cell proliferation within the microcapsules.
    RESULTS AND CONCLUSION: The integrity rate of glucose-responsive alginate/modified-chitosan/alginate microcapsules could be 95% after 48 hours oscillation, and the hardness of microcapsules lowered, but the elasticity increased. The permeability test showed that microcapsules intercepted macromolecular substances such as bovine serum albumin and immuno-globulin G. The microcapsules could release more insulin with the increase of glucose concentration. As described above, the glucose-responsive alginate/modified-chitosan/ alginate microcapsules had good mechanical strength, immunoisolation effect and glucose sensitivity. The β-TC3 cells entrapped in the glucose-responsive microcapsules could grow well and the peak of cell proliferation lagged behind as compared with non-microencapsulated cells, indicating the glucose-responsive microcapsules had good biocompatibility.

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    Preparation and properties for magnetic/pH double sensitive hydrogel beads carrying carbamazepine
    Xie Ming-quan, Liu Hui-juan, Li Ping, Li Yu-min
    2013, 17 (29):  5337-5344.  doi: 10.3969/j.issn.2095-4344.2013.29.012
    Abstract ( 324 )   PDF (1281KB) ( 549 )   Save

    BACKGROUND: The faults or defects in pharmaceutical dosage form designed for carbamazepine may lead to irregular drug absorption, great individual differences between the pharmacokinetics, narrow therapeutic concentration range, and the therapeutic drug monitoring for this drug.
    OBJECTIVE: To prepare a magnetic/pH double sensitive hydrogel beads carrying carbamazepine and to evaluate its properties.
    METHODS: Using chitosan, alginate and Fe3O4 nanoparticle as carrier materials, the magnetic/pH double sensitive hydrogel beads carrying anti-epileptic carbamazepine were prepared, and the composition and preparation technology were optimized by orthogonal test of L9(34). The surface morphology and structure of the hydrogel beads were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy respectively. Also, the superparamagnetism, swelling and release in vitro of hydrogel beads were determined.
    RESULTS AND CONCLUSION: The optimized preparation technology were described as: 0.5% (w/v) chitosan, 1.5% (w/v) alginate, 2.0% (w/v) calcium chloride, and 1:2 ratio for magnetic versus carrier materials. The hydrogel beads under the optimal preparation conditions showed a round shape and smooth surface, and average encapsulation efficiency, loading efficiency and hydrogel beads diameter were 94.36%, 25.05% and 1-2 mm respectively. The hydrogel beads appeared to have superparamagnetism, the swelling degrees were associated with pH value of medium, and the sequential release amount of carbamazepine from the hydrogel beads in simulated gastric fluid was 22.77% for 2 hours. Then, the beads were moved to the simulated intestinal fluid, and this value approached 91.63% for 24 hours. Experimental findings indicate that, the composition and preparation technology of magnetic/pH double sensitive hydrogel beads carrying carbamazepine was rational and feasible, and hydrogel beads show obvious pH sensitivity and magnetic sensitivety. The controlled-release effect of hydrogel beads in vitro is also good.

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    Dual-drug sustained-release carrier: Preparation and performance
    Bao Yu-cheng, Zhang Wen-long, Wang Yong, Zhang Jie, Wang Yong-mei
    2013, 17 (29):  5345-5350.  doi: 10.3969/j.issn.2095-4344.2013.29.013
    Abstract ( 364 )   PDF (867KB) ( 545 )   Save

    BACKGROUND: During conventional treatment for bone tuberculosis, there is a low effective concentration of anti-tuberculosis drugs, and the therapeutic effect is poor.
    OBJECTIVE: To develop a new biomaterial as a slow-release artificial carrier that can be directly implanted into the surrounding tissue of bone tuberculosis, maintain a certain anti-tuberculosis drug concentration for a long time, thereby playing an effective therapeutic action.
    METHODS: Rifampicin/polylactic acid/glycolic acid microspheres and isoniazid/polylactic acid/glycolic acid microspheres were prepared using the emulsion-solvent evaporation method. Using α-cyanoacrylate, a biological adhesive, two kinds of microspheres were processed into a long-term slow-release bicomponent drug carrier. Then, in vitro release characteristics of the dual-drug sustained-release carrier were observed. After that, the dual-drug sustained-release carrier was implanted into rabbit intertrochanteric femur bone defects for observing drug release concentrations, histocompatibility and bone defect healing at different time points after drug delivery carrier implantation.
    RESULTS AND CONCLUSION: For rifampicin/polylactic acid/glycolic acid microspheres, the mean particle size was (240±13) μm, and the drug loading load rate was (26±1.5)%. For isoniazid/polylactic acid/glycolic acid microspheres, the mean particle size was (250±10) μm, and drug loading rate was (28±1.8)%. The in vitro cumulative release rate could reach 80% for rifampicin and 90% for isoniazid at day 90. The in vivo released concentration of rifampicin and isoniazid within 90 days was (0.5±0.4) and (0.6±0.3) μg/g, respectively. There were a small amount of infiltrated neutrophils between the fascia and muscle fibers after the drug delivery carrier was implanted, and the amount of neutrophils in the muscle were reduced significantly at day 59. X-ray plain film showed that bone defects decreased obviously in size. These findings indicate that this dual-drug sustained-release carrier can maintain a certain anti-tuberculosis drug concentration in the surrounding tissues of bone tuberculosis, which is expected to provide a new type of dual-drug delivery carrier in the surgical treatment of bone tuberculosis.

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    Drug release characteristics of gatifloxacin-poly sebacic anhydride local controlled release system
    Lu Feng, Zhang Hong-tu, Ma Shu-you
    2013, 17 (29):  5351-5356.  doi: 10.3969/j.issn.2095-4344.2013.29.014
    Abstract ( 425 )   PDF (907KB) ( 421 )   Save

    BACKGROUND: High-dose antibiotics for bone infection have many adverse reactions, and its outcomes are not perfect. Thus, to explore a degradable material as a vector to prevent bone infection is valuable.
    OBJECTIVE: To study drug release characteristics of gatifloxa-poly sebacic anhydride local controlled release system in vivo.
    METHODS: A 3 mm × 6 mm bone window was made at right knee joint of New Zealand rabbits. The gatifloxacin-poly sebacic anhydride sustained release preparation was implanted. Heart blood, bone tissue and myeloid tissue specimens were obtained at 1, 2, 3, 6, 9, 12, 15, 18, 25 and 30 days after surgery. High-performance liquid chromatography was utilized to determine gatifloxacin concentration. Scanning electron microscope was employed to observe the structural changes before and after implantation of gatifloxacin-poly sebacic anhydride sustained release preparation.
    RESULTS AND CONCLUSION: After implantation of gatifloxacin-poly sebacic anhydride sustained release preparation, drug concentration gradually decreased in the myeloid tissue, peaked at 1 day, stabilized at 3-15 days, gradually reduced at 15-30 days. However, the drug concentration was still higher than the minimal inhibitory concentration 0.1 mg/L against Staphylococcus aureus at 30 days. The peak of drug concentration in the bone tissue occurred at 3 days, and stabilized at other days, which was higher than 0.1 mg/L. At the same time point, drug concentration in the blood specimen was lower than that in the myeloid tissue and bone tissue. The degradation of gatifloxacin-poly sebacic anhydride sustained release preparation was surface erosion, and the shape of the degradation residue is small globular. The change of the internal structure of gatifloxacin-poly sebacic anhydride sustained release preparation was not found. In the drug release procedure, gatifloxacin-poly sebacic anhydride sustained release preparation did not show disintegration or fragmentation. These results indicated that gatifloxacin-poly sebacic anhydride local sustained release preparation has good abilities of drug load and drug release.

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    Preparation of gelatin-magnetic micro-capsules by condensation method
    Xian Yuan-fang, Wang Wen-ting, Yu Wei, Tu Li-hui, Wang Sheng-hai, Zou Cheng, Min Xiao-feng
    2013, 17 (29):  5357-5363.  doi: 10.3969/j.issn.2095-4344.2013.29.015
    Abstract ( 533 )   PDF (840KB) ( 538 )   Save

    BACKGROUND: Compared with conventional medications, drug micro-capsule system can control the release of drugs and have well target properties and biocompatibility. The drugs can be concentrated at the focus and play an important role in clinic.
    OBJECTIVE: To prepare dacarbazine magnetic micro-capsules with different capsule materials and gelatin complex by coacervation, and to optimize capsule materials and preparation process.
    METHODS: Fe3O4 magnetic materials were prepared with chemical coprecipitation method. With the solution complex coacervation, we prepared the gelatin-Arabic gum magnetic micro-capsule, gelatin-sodium alginate magnetic micro-capsules, gelatin-sodium carboxymethyl cellulose magnetic micro-capsules, and gelatin-chitosan magnetic micro-capsules. With the emulsion complex coacervation method, we further prepared the gelatin-Arabic gum magnetic micro-capsule, gelatin-sodium alginate magnetic micro-capsules, gelatin-sodium carboxymethyl cellulose magnetic micro-capsules, and gelatin-chitosan magnetic micro-capsules. The magnetic gelatin micro-capsules and magnetic chitosan micro-capsules were prepared with single coagulation method. The micro-capsules were determined for the embedding rate, the magnetic susceptibility, the micro-capsule size and the release performance, to define the optimal preparation technology of dacarbazine magnetic micro-capsules.
    RESULTS AND CONCLUSION: The solution complex coacervation method was better than the emulsion coacervation method. As for the solution complex coacervation method, the optimal capsule material was gelatin-sodium alginate, with drug embedding rate 37.90%, the yield rate 72.31%, and the average magnetization intensity 8.53 emu/g. The second material was gelatin-chitosan. As a capsule material, the gelatin was better than chitosan with single coagulation method. Drug embedding rate was 51.58%, the yield rate was 64.50%, and the average magnetization was 6.93 emu/g. Single coagulation method was better than coacervation method.

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    Three-dimensional printing of titanium/hydroxyapatite composite and functionally graded materials
    Qian Chao, Fan Ying-zi, Sun Jian
    2013, 17 (29):  5364-5370.  doi: 10.3969/j.issn.2095-4344.2013.29.016
    Abstract ( 327 )   PDF (947KB) ( 672 )   Save

    BACKGROUND: Preparation of titanium/hydroxyapatite composite by conventional methods has the deficiency of simple structure, low degree of automation and difficulty in porosity and pore size control, which limits the diverse process and manufacture.
    OBJECTIVE: To evaluate the feasibility of three-dimensional printing technology for the preparation of titanium/hydroxyapatite composite and titanium/hydroxyapatite functionally graded material molding.
    METHODS: A CAD model of titanium/hydroxyapatite composite was designed to be the cylinder (diameter     25 mm, height 20 mm), while the titanium/hydroxyapatite functionally graded implant designed as a CAD model of the cylinder with 25 mm in diameter asnd 10 mm in height with two layers, the upper layer with titanium powder and the lower layer with titanium/hydroxyapatite powder. The composite and functionally graded implant were processed by the three-dimensional printing and sintered. The sintered titanium/hydroxyapatite composite and titanium/hydroxyapatite functionally graded implant were observed for their microstructures, and the X-ray diffraction analysis and compressive strength testing were performed.
    RESULTS AND CONCLUSION: The sintered titanium/hydroxyapatite composite and titanium/hydroxyapatite functionally graded implant had uniform contraction and no obvious distortion. The sintered titanium/ hydroxyapatite composite had the aperture size from 50 to 150 μm. There occurred a chemical reaction between titanium and hydroxyapatite during the sintering process, obtaining the new creations of Ca3(PO4)2, CaTiO3, TiO2 and CaO. Its compressive strength was (184.3±27.1) MPa. The microstructure of titanium/hydroxyapatite functionally graded implant had graded structures with a visible line between the two layers. The results of the microstructure and mechanical properties of titanium/hydroxyapatite composite and titanium/hydroxyapatite functionally graded implant can meet the requirements of medical biological implant materials.

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    Degradable properties of biodegradable composite stents in the trachea
    Ma Yong-fu, Liu Yang, Guo Jun-tang, Zhang Tao, Liang Chao-yang
    2013, 17 (29):  5371-5378.  doi: 10.3969/j.issn.2095-4344.2013.29.017
    Abstract ( 330 )   PDF (894KB) ( 649 )   Save

    BACKGROUND: Through a full 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 (M150 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.
    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.

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    Structural characteristics and advantages of a self-assembling peptide nanofiber scaffold
    Yuan Liang-liang, Liang Peng
    2013, 17 (29):  5379-5386.  doi: 10.3969/j.issn.2095-4344.2013.29.018
    Abstract ( 1153 )   PDF (894KB) ( 1610 )   Save

    BACKGROUND: Three-dimensional self-assembling peptide nanofiber hydrogel scaffold can simulate the in vivo microenvironment and provide a structural model for cells, which promotes the right composition of extracellular matrix and cell growth, as well as improves the cell functions.
    OBJECTIVE: To review the fundamental research and the experimental study of the self-assembling peptide nanofiber scaffold in the nerve tissue engineering. 
    METHODS: Literatures concerning basic and experimental studies on the self-assembling peptide nanofiber scaffold in the nerve tissue engineering were reviewed via searching PubMed and VIP databases (2000/2013) using the key words of “self-assembling peptide, nanofiber scaffold, RADA16, nerve tissue engineering, neural stem cell.
    RESULTS AND CONCLUSION: Self-assembling peptide nanofiber scaffold is a novel and ideal tissue engineering material which provides new method for nerve injury repairing, for it not only solves the problem of poor compatibility between the material and cells, but also plays a much more pivotal role in maintaining three-dimensional properties, promoting cell activities and mimicking the extracellular matrix, which is superior to other materials. However, there still exist some challenges in the area of self-assembling peptides, including short-term issues such as integrating of self-assembling peptide with bio-macromolecular material or relatively developed traditional transplant; and long-term issues such as adapting immune system in vivo, treating targets within cells and anticipating the future fate of highly integrated scaffolds.

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    A new vascular tissue engineering material: Electrospun small-diameter nanofibous scaffolds
    Wu Tong, Huang Chen, Mo Xiu-mei
    2013, 17 (29):  5387-5394.  doi: 10.3969/j.issn.2095-4344.2013.29.019
    Abstract ( 558 )   PDF (514KB) ( 965 )   Save

    BACKGROUND: Due to the much higher requirement of biocompatibility and anticoagulant of small-diameter vascular grafts than those of large-diameter ones, in situ blood vessel regeneration occurs as a new research direction.
    OBJECTIVE: To summarize the recent research development of electrospun small-diameter scaffolds and to explore the application of in situ blood vessel regeneration and the development tendency.
    METHODS: The first author retrieved China National Knowledge Infrastructure database, Wanfang data and ISI Web of Knowledge foreign database to retrieve literatures addressing the fabrication of electrospun small-diameter nanofibrous vascular grafts, surface modification and mimicking extracellular matrix, as well as the evaluation of biocompatibility and security after grafting.
    RESULTS AND CONCLUSION: Electrospun small-diameter nanofibrous vascular grafts have emerged as promising candidates in vascular tissue engineering. By using both natural and synthetic polymers, the scaffolds can achieve a good balance between mechanical property and biocompatibility. Meanwhile, the fabrication of multi-layered vascular scaffolds, functional surface modification and mimicking extracellular matrix structurally and functionally are now becoming attractive research directions. However, at current stage, electrospun vascular scaffolds used clinically are basically formed by synthetic materials, which have limited biocompatibility and anticoagulant activity. In this case, more efforts should be paid to find an optimal ratio between natural and synthetic materials for the improvement of biocompatibility and anticoagulant ability of small-diameter vascular grafts.

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    Titanium implants: Strategies on surface modification and effect on osseointegration
    Li Ying, Li Chang-yi
    2013, 17 (29):  5395-5402.  doi: 10.3969/j.issn.2095-4344.2013.29.020
    Abstract ( 536 )   PDF (724KB) ( 950 )   Save

    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 cell and the tissue in order to use better surface modification technology to fulfill the early and more stable osseointegration between the implant and bone tissue.

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    Three-dimensional finite element analysis of prosthesis stress variation
    Zhan Liu, Xie Shu-juan, Pan Wei-hong
    2013, 17 (29):  5403-5408.  doi: 10.3969/j.issn.2095-4344.2013.29.021
    Abstract ( 548 )   PDF (811KB) ( 574 )   Save

    BACKGROUND: Based on variational principle and weighting technology of three-dimensional finite element method, human teeth with a complex morphology can be modeled, which helps to understand the stress distribution of dental hard tissue and prosthesis during the dynamic repair process.
    OBJECTIVE: To comprehensively analyze the three-dimensional finite element studies concerning biomechanics of dental prostheses, focusing on the effects of metal crown, porcelain thickness, root canal preparation and filling on the tooth stress.
    METHODS: A computer-based search of PubMed (1993-04/2012-09), China Academic Journal Network Publishing Database (2001-2008), and VIP (2001-2008) was performed by the first author to retrieve articles concerning the effects of metal crown, porcelain thickness, root canal preparation and filling on the tooth stress. The keywords were “porcelain-fused-to-metal, finite element method, stress analysis, root canal” in English and Chinese. Articles with repetitive contents or meta-analysis were ruled out. Then 40 articles were suitable for further analysis.
    RESULTS AND CONCLUSION: Finite element method has important significance to establish high-fidelity and high-accuracy models in oral medicine, thereby providing effective biomechanical information for the root canal treatment and post-treatment repair. Scholars continue to explore the stress distribution of dental prostheses during chewing. This review summarizes the stress changes of post and core crowns, supporting reference for further research. Three-dimensional finite element method can be used to build nonlinear three-dimensional finite element models with anisotropic biomechanical characteristics, and can gradually improve the transition from static analysis to a dynamic analysis, truly achieving accurate simulation of oral biology and dental morphology as well as chewing function of the teeth.

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    Antibiotic bone cement and renovation after artificial joint replacement
    Li Wen-cheng
    2013, 17 (29):  5409-5414.  doi: 10.3969/j.issn.2095-4344.2013.29.022
    Abstract ( 482 )   PDF (654KB) ( 578 )   Save

    BACKGROUND: Antibiotic bone cement is the important method for the prevention and treatment of infection after artificial hip replacement and renovation.
    OBJECTIVE: To review the research progress of antibiotic bone cement.
    METHODS: A computer-based online search was performed in PubMed database, CNKI database, Chinese Biomedical Literature database, VIP database and Wanfang database for the literatures from 1978 to 2012. The key words were “bone cement, antibiotic bone cement, infection, joint replacement” in English and Chinese.
    RESUTLS AND CONCLUSION: A total of 335 literatures were screened out. Finally, 29 literatures were included for in-depth analysis after the primary screen through reading the title, abstract and full-text. Antibiotic bone cement has been widely used in the treatment of infection after artificial joint replacement and renovation as it can reduce the risk of infection after initial joint replacement and renovation. The material properties and mechanical properties will not change after bone cement mixed with appropriate amount of antibiotic. Different antibiotics in the bone cement have different release rates, which were closely related with the porosity of bone cement. Adding the additive that used for increasing the porosity of bone cement can increase the antibiotic release.

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    Artificial dura materials in neurosurgical procedures: An analysis of 100 cases
    Wei Peng-xiang, Li Dan-qing, Zhou Yu-jia, Liu Jia-lin, Wang Lei
    2013, 17 (29):  5415-5420.  doi: 10.3969/j.issn.2095-4344.2013.29.023
    Abstract ( 893 )   PDF (711KB) ( 930 )   Save

    BACKGROUND: The meningeal defect patients can be treated with artificial dural materials combined neurosurgical techniques which can protect the integrity of brain tissue.
    OBJECTIVE: To analyze the biocompatibility and application feasibility of various artificial dura mater materials.
    METHODS: The artificial dura materials were classified according to the different sources, and the biocompatible and application feasibility of various artificial dura mater materials were analyzed, as well as the advantages and disadvantages of various materials. The anticoagulant and hemolytic properties of the materials were analyzed through recalcification test and hemolysis test. 100 patients receiving collagen membrane repair selected from Department of Neurosurgery, Dongfang Hospital of Beijing University of Chinese Medicine were observed.
    RESULTS AND CONCLUSION: The dural repair materials mainly include autologous material, allograft materials, dissimilar materials, synthetic materials and natural materials. Each kind of material has its advantages and disadvantages. Meningeal defect complications include cerebrospinal fluid leakage, pseudo meninges, infection and arachnoiditis. There are many problems of artificial dural materials to be solved, and the novel biological dural materials and absorbable materials are the direction of dural material research.

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