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    28 February 2017, Volume 21 Issue 6 Previous Issue    Next Issue
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    Preparation and characterization of an injectable bioactive calcium phosphate material for bone repair
    Liu Jian-xiu, Shen Ying, Chu Bin, Zeng Fei, Huang Shi-jia, Li Song-jian
    2017, 21 (6):  821-828.  doi: 10.3969/j.issn.2095-4344.2017.06.001
    Abstract ( 436 )   PDF (2612KB) ( 329 )   Save

    BACKGROUND: In view of the unavoidable problems of autogenous and allogenous bone grafts, it is an urgent need to develop biodegradable bone substitute materials, among which is calcium phosphate material that has become a hot spot in the domestic and foreign research.
    OBJECTIVE: To develop a biodegradable calcium phosphate material for bone repair based on tetracalcium phosphate (TTCP).
    METHODS: The biodegradable calcium phosphate cement made from TTCP, dicalcium phosphate anhydrous and different constituents of curing liquids was prepared under room temperature (about 25 ℃). The effects of solid components, liquid components as well as calcinations and drying temperature on the physical and biological performances were detected through X-ray diffraction test, hardness test, decay in a simulated body fluid, hemolysis and cytotoxicity tests, respectively, to select the bone repair material with excellent performances.
    RESULTS AND CONCLUSION: When the calcination temperature was lower than 1 300 ℃, TTCP was rarely available; only close to 1 400 ℃, the relatively pure TTCP was gained. A large number of pure TTCP were gained by rapid cooling because of avoidance of the moisture impact, but slow cooling made the main products to be hydroxyapatite, suggesting that rapid cooling is essential to obtain pure TTCP. With the increase of the proportion of citric acid solution in the liquid phase, the pH values and the hemolysis rate in the bone cement soak solution were increased gradually, illustrating that citric acid solution is easy to induce hemolysis. In vitro cell experiments showed that the hemolysis rate of bone cement with a solution of 2:1 NH4/Na ratio was the lowest, and the biocompatibility was the best, which was the most favorable to cell growth. Cements was made of calcined powders sieved at 1 400 ℃ and showed the shortest initial setting time, least effect on pH values, lowest disintegration rate and hemolysis rate, and slightest inhibition effect on the cell proliferation, indicating that the bone cements made of sieved powder after 1 400 ℃ calcination is more suitable for clinical application. 

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    Calcium sulfate bone cement with or without injectable polyamino acid for goat vertebral defects: a comparative experiment
    Wang Xian-di, Chen Guo, Li Zhu-hai, Jiang Hu-shan, Nie Hong-fei, Xie Tian-hang, Huang Hong-jie, Pei Fu-xing, Song Yue-ming, Zeng Jian-cheng
    2017, 21 (6):  829-835.  doi: 10.3969/j.issn.2095-4344.2017.06.002
    Abstract ( 498 )   PDF (5611KB) ( 211 )   Save

    BACKGROUND: Our previous study has proved that the novel injectable polyamino acid/calcium sulfate (PAA/CS) bone cement possesses a good safety and biocompatibility. But its repair effect on spinal defects is never reported.
    OBJECTIVE: To evaluate the degradability and osteogenesis of the PAA/CS bone cement in vertebral repair.
    METHODS: Twelve healthy adult female goats were selected. The vertebral defects of φ4 mm×15 mm were prepared through the right lumbar pedicle, and the vertebrae of each goat were then randomly divided into two groups (groups A and B), followed by filled with the injectable CS or PAA/CS, respectively. The goats were sacrificed at 4, 8, 12 and 16 weeks after surgery, and micro-CT scan, quantitative analysis and histological observation were conducted.
    RESULTS AND CONCLUSION: New trabeculae grew in the defect area from the edging to the center in the two groups. At the end of 4 weeks, no filling material was found in the two groups, and the defect region was clear. At the end of 6 weeks, there was still an irregular cavity in the bone defect of the group A and the newly-formed trabeculae were dense and arranged disorderly. In the group B, the defect region was almost filled with trabeculae that were clear and connected well. With time, the bone volume fraction, thickness and number of trabeculae were on a rise, while the trabecular separation was in decline in both two groups. Histological observation showed that there were a large number of new trabeculae in both two groups, a part of which were connected, but most of which had the similar structures to normal trabeculae at the 16th week. These results suggest that the PAA/CS bone cement can be degraded thoroughly in vivo and has better osteogenesis than the CS. Addition of 10% PAA does not significantly delay the degradation of PAA/CS bone cement.

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    Three-dimensional culture and differentiation of biological bone tissue and its in vivo repair effect in an animal model 
    Wang Yan1, Wang Han-zhong2, Zhang Ying1, Zhang Li-jun1, Tian Jian-ming2, Chen Xian-xiong3
    2017, 21 (6):  836-842.  doi: 10.3969/j.issn.2095-4344.2017.06.003
    Abstract ( 455 )   PDF (8632KB) ( 233 )   Save

    BACKGROUND: In vitro culture of tissue-engineered bone is an important method for bone repair. Three-dimensional (3D) printed bone stents combined with bioreactor culture are of significance in bone tissue engineering.
    OBJECTIVE: To study the in vivo repair effect of the 3D printed biomaterial scaffold with human mesenchymal stem cells (hMSCs) cultured in bioreactor. 
    METHODS: The scaffold was constructed by poly(lactic-co-glycollic acid)/hydroxyapatite (PLGA/HA) via 3D printing and freeze-dying techniques, and then hMSCs were seeded onto the scaffold and cultured in bioreactors. All rabbits were numbered and divided into control (No.1 and 2), experimental 1 (No. 3 and 4) and experimental 2 (No. 5 and 6) groups, and each group had two subgroups positive and negative. The rabbit left distal femur in each group was modeled into bone defect and the single PLGA/HA scaffold, PLGA/HA scaffold carrying non-induced hMSCs were implanted in the positive and negative groups of the control group, respectively; the PLGA/HA-201 405-1 and PLGA/HA-201 405-2 carrying induced hMSCs were implanted into the positive and negative subgroups of the experimental 1 and 2 groups, respectively. Additionally, the right femur in the experimental 2 group was drilled only. The osteogenesis ability and biodegradability were determined using electron microscope, the in vivo repair was observed through CT examination, and the histopathological examination was performed after bone healing. 
    RESULTS AND CONCLUSION: The scaffold with topological structure suitable for cell seeding was prepared. A large number of new calcium nodules were observed under electron microscope in the experimental groups indicating overt achievement in bone healing. These results suggest that the prepared scaffold achieves a good repair effect preliminarily.

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    Stromal vascular fraction combined with acellular bone matrix-chitosan scaffold for radical defect repair
    Shao Qing-dong, Wang Zheng, Li Yu-fei, Xu Tian-ming, Sun Jiu-yi, Jiang Feng, Lv Feng-xia
    2017, 21 (6):  843-847.  doi: 10.3969/j.issn.2095-4344.2017.06.004
    Abstract ( 391 )   PDF (4477KB) ( 245 )   Save

    BACKGROUND: Artificial tissue-engineered bone combined with acellular bone matrix has been shown to be favorable for bone repair.
    OBJECTIVE: To explore the safety and biocompatibility of the stromal vascular fraction of the adipose tissue combined with the acellular bone matrix-chitosan scaffold in the repair of rabbit radial defects.
    METHODS: A total of 38 New Zealand rabbits were selected, 3 rabbits were used to extract stromal vascular fraction of adipose tissue, 3 used to prepare acellular bone matrix and 32 divided into experimental and control groups. Models of rabbit radial defects were established using Brownlow method. The rabbits in the experimental group were treated with the SVF of adipose tissue combined with the acellular bone matrix-chitosan scaffold, while those controls received no treatment. General situation, gross observation, X-ray examination, histological observation and Lane-Sandhu scores were performed at 2 and 4 months postoperatively.
    RESULTS AND CONCLUSION: No infections occurred in both two groups at 2 and 4 months postoperatively, but the activity level and degree of healing in the experimental group were significantly better than those in the control group. In the experimental group, there were high-density shadows at 2 months postoperatively and the X-ray image of the bone defect site was the same as that of the normal one at 4 months, while bone nonunion occurred in the control group. The bone tissues in the experimental group grew significantly better than that in the control group at 2 and 4 months postoperatively, and the Lane-Sandhu histological scores in the experimental group were significantly higher than those in the control group at 2 and 4 months postoperatively (P < 0.05). These results indicate that the stromal vascular fraction combined with the acellular bone matrix-chitosan scaffold exhibits safety and biocompatibility in the repair of rabbit radical defects. 

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    Implantation of tissue-engineered bone with vascular bundles or sensory nerve tracts for large femoral defects: the middle- and long-term expression of calcitonin gene related peptide type I receptor
    Chen Si-yuan, Wang Le, Jiang Shan, Pei Guo-xian
    2017, 21 (6):  848-853.  doi: 10.3969/j.issn.2095-4344.2017.06.005
    Abstract ( 428 )   PDF (6255KB) ( 215 )   Save

    BACKGROUND: Previous study has proved that implantation of the tissue-engineering bone with vascular bundles or sensory nerve tracts can promote bone formation, which may be related to the expression of sensory neuropeptide receptors.
    OBJECTIVE: To investigate the effect of implantation of tissue-engineered bone containing vascular bundles and sensory nerve tracts on the middle- and long-term expression of calcitonin gene-related peptide type I receptor (CGRP1R) in the repair of rabbit large femoral defects.
    METHODS: Thirty-six New Zealand white rabbits were enrolled and modeled into 1.5 cm femoral defects, and then randomized into three groups. Bone marrow mesenchymal stem cells (BMSCs) were subjected to osteoblastic induction for 7 days, and then seeded onto the β-calcium phosphate scaffold to construct the tissue-engineered scaffold. In sensory nerve group, the tissue-engineered scaffold was implanted into the defect region, and autologous sensory nerve bundles were implanted into the lateral groove of the tissue-engineered bone; in vascular bundle group, the tissue-engineered scaffold was implanted, and autologous femoral blood bundles were implanted into the lateral groove of the tissue-engineered bone; in blank control group, only the tissue-engineered scaffold was implanted. X-ray examination, immunohistochemistry and real-time PCR were performed at 24 and 48 weeks postoperatively.
    RESULTS AND CONCLUSION: The X-ray scores in the sensory nerve and vascular bundle groups were significantly higher than that in the control group (P < 0.05), but no significant difference was found between sensory nerve and vascular bundle groups. Real-time PCR found that the expression level of CGRP1R mRNA in the vascular bundle group was significantly higher than that in the other two groups (P < 0.05), but showed no significant difference between sensory nerve and blank control groups. Immunohistochemistry findings showed that CGRP1R positive expression rate in the sensory nerve and vascular bundle groups was higher than that in the blank control group. These results reveal that implantation of the tissue-engineered bone containing vascular bundles can promote the CGRP1R expression. 

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    Bioactive glass modified polyethylene terephthalate promotes bone healing
    Zhai Xin-yuan1, Lin Xiao-feng2
    2017, 21 (6):  854-858.  doi: 10.3969/j.issn.2095-4344.2017.06.006
    Abstract ( 501 )   PDF (4659KB) ( 292 )   Save

    BACKGROUND: Polyethylene terephthalate (PEA) holds good mechanical properties, but its biocompatibility needs to be improved.
    OBJECTIVE: To investigate the effect of bioactive glass modified PEA on bone healing.
    METHODS: In vitro experiment: PEA (control group) and bioactive glass modified PEA (experimental group) were respectively co-cultured with MC3T3-E1 cells. The cell morphology was observed at 3 days of culture, and the cell proliferation and alkaline phosphatase activity were detected at 1, 3 and 5 days of culture. In vivo experiment: 24 New Zealand white rabbits were enrolled, modeled into unilateral knee ligament rupture, and then randomly allotted to two groups. Bioactive glass modified PEA and PEA were implanted into experimental and control groups, respectively. Biomechanics and histological changes were compared between groups at 6 and 12 weeks after transplantation.
    RESULTS AND CONCLUSION: In vitro experiment: the cell density in the experimental group was significantly higher than that in the control group after 3-day culture (P < 0.05); the cell proliferation and alkaline phosphatase activity were significantly higher than those in the control group at 3 and 5 days of culture (P < 0.05). In vivo experiment: the maximum axial pull-out strength in the experimental group was significantly greater than that in the control group at 6 and 12 weeks after implantation (P < 0.05). In the control group, the defect was obvious and there were a large number of inflammatory cells at 6 weeks after implantation; the defect region became fuzzy, abundant inflammatory cells existed and new bone formed on the surface at 12 weeks after implantation. In the experimental group, there were newly formed bones and trabeculae formed on the interface, the scar tissue became less, and the interface width was narrow at 6 weeks after implantation; numerous new tissues were observed, and only a few inflammatory cells observed in the defect region at 12 weeks after implantation. These results indicate that the modified PEA with bioactive glass possesses good biocompatibility and biomechanics, which can promote bone healing.

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    Canine femoral artery displacement with the chitosan-sulfated silk fibroin artificial blood vessel: the formation of vascular endothelial cells, vascular smooth muscle cells and fibroblasts
    Ma Li, Xie Yi-xu, Chang Yu, Ma Li
    2017, 21 (6):  859-863.  doi: 10.3969/j.issn.2095-4344.2017.06.007
    Abstract ( 362 )   PDF (5083KB) ( 284 )   Save

    BACKGROUND: The chitosan-sulfated silk fibroin artificial blood vessel was obtained in our previous study.
    OBJECTIVE: To investigate the biocompatibility and function of the chitosan-sulfated silk fibroin artificial blood vessel replacement into the canine femoral artery.
    METHODS: Eight Beagles were randomly allotted to two groups, and chitosan-sulfated silk fibroin artificial blood vessel was implanted into the femoral artery (experimental group), but animalsin control group received no intervention. Six months after implantation, the coagulation function was detected, the vascular formation, including endothelial, smooth muscle and fibroblast layers were observed through hematoxylin-eosin staining under electron microscope.
    RESULTS AND CONCLUSION: (1) Hematoxylin-eosin staining showed that vascular endothelial cells, vascular smooth muscle cells and fibroblasts were found in the experimental group, which were similar with the normal vascular structures. (2) Immunohistochemistry: in the experimental group, there was a deeply stained band at the tissue edege through Factor VIII staining, suggesting the formation of the endothelium; there were abundant brown particles precipitated in á-SMA staining, suggesting the vascular smooth muscle cell formation; Vimentin staining showed various brown particle precipitations indicating the fibroblast formation, and all were close to the normal vascular structures. (3) Electron microscope observed that the inner surface and section of the artificial vessel were similar with the normal one, and the three-layer structures formed in the section arranged irregularly. (4) There were no differences in the prothrombin time, activated partial thromboplastin time, thrombin time and fibrinogen between groups. To conclude, these results suggest that the chitosan-sulfated silk fibroin artificial blood vessel holds good biocompatibility and performances.

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    Degradation rate of collagen-chitosan composite scaffold implanted into different rat tissues
    Fu Feng, Qin Zhe, Li Xiao-hong, Chen Chong, Wang Li-na, Xu Chao, Tu Yue, Zhang Sai
    2017, 21 (6):  864-870.  doi: 10.3969/j.issn.2095-4344.2017.06.008
    Abstract ( 406 )   PDF (6538KB) ( 324 )   Save

    BACKGROUND: Biological scaffolds should be gradually degraded with the formation of new tissues, so the degradation rate is an important index for evaluating scaffold materials. Conventional testing methods make an impact on the assessment of the scaffold degradation rate at different sites due to some limitations.
    OBJECTIVE: To evaluate the degradation rate of collagen-chitosan (CG-CS) composite implanted into the subcutaneous, spinal cord and brain tissues of Sprague-Dawley rats and to explore the underlying mechanism.
    METHODS: A 3 mm×3 mm disc-shaped CG-CS composite scaffold was prepared, and its microstructure was observed under scanning electron microscope. Nerve stem cells were co-cultured with CG-CS scaffold, and then the cell viability was detected through cell counting kit-8 assay to assess the biocompatibility. Sprague-Dawley rats were randomly divided into three groups: cortex, spinal cord, and subcutaneous groups. The CG-CS scaffold was implanted into cortex, spinal cord T9, or back T9, respectively. The rats were sacrificed at different time points, and three rats in each group were subjected to the scaffold removal to evaluate the scaffold degradation rate. The resting rats were used to prepare the tissue sections for histological observation of the scaffold and the surrounding tissues.
    RESULTS AND CONCLUSION: Scanning electron microscope revealed that the CG-CS composite scaffold had a three-dimensional porous structure with a pore size that met the biological requirements of in vivo transplantation. The in vivo experiments showed that no graft rejection occurred, suggesting that the scaffold has good biocompatibility. The degradation rate was fastest in the subcutaneous group, and the scaffold was degraded completely with 12 days, which was significantly higher than that in the spinal cord and brain groups (P < 0.05). The degradation rate in the spinal cord group was significantly higher than that in the brain group since the 3rd week (P < 0.05); the scaffold degraded completely in the spinal cord group, while the partial scaffold could still be found in the brain group. The number of blood vessels and the scores of macrophage infiltration were as follows: subcutaneous group > spinal cord group > brain group (P < 0.05). Our findings suggest that the CG-CS scaffold holds a good biocompatibility and its degradation rate differs significantly among groups. In the field of tissue engineering, the complex microenvironment of target tissues and the host response after stent implantation should have effects on the balance between the biodegradation rate and reconstitution rate of the organism.

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    Collagen type II-modified acellular dermal membrane promotes the repair of cartilage defects
    Zhang Bai-qing, Zhang Zhong-wen, Sun Lei, Jiang Jian, Wu Xia
    2017, 21 (6):  871-876.  doi: 10.3969/j.issn.2095-4344.2017.06.009
    Abstract ( 409 )   PDF (6520KB) ( 391 )   Save

    BACKGROUND: Previous study has observed that the calf acellular dermal membrane exhibits slow repair efficiency, fast degradability speed and other shortcomings in the repair of cartilage defects.
    OBJECTIVE: To investigate the repair effect of the collagen type II-modified acellular dermal membrane on cartilage defects in rabbits.
    METHODS: The fetal rabbit chondrocytes were seeded onto the collagen type II-modified acellular dermal membrane, and the composite was then observed under scanning electron microscope at 3, 7 and 14 days. Cartilage defect models were established on the bilateral femoral condyles of 24 New Zealand white rabbits, and these model rabbits were randomly allocated to three groups. The cartilage-acellular dermal membrane and cartilage-collagen type II-modified acellular dermal membrane were implanted into the defect regions of control and experimental groups, respectively. Those received no intervention were as blank control group. Collagen type II immunohistochemical staining and Wakitani scoring system were performed at 6 and 12 weeks postoperatively.
    RESULTS AND CONCLUSION: Chondrocytes grew and adhered well in the scaffold. The Wakitani scores in the experimental group were significantly lower than those in the control and blank control groups at postoperative 6 and 12 weeks (P < 0.05). At 6 and 12 weeks postoperatively, collagen type II immunohistochemical staining was the strongest in the experimental group, with yellow and brown particles in the cytoplasm; the control group was positive for collagen type II immunohistochemical staining, while the blank control group was negative for the staining. Our findings suggest that the collagen type II-modified acellular dermal membrane is beneficial for the repair of cartilage defects.

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    Basic fibroblast growth factor-chitosan carrier induces neural stem cells to differentiate into neurons followed by co-culture with myocytes
    Zhai Jing-yan, Duan Hong-mei, Shang Jun-kui, Yang Zhao-yang, Li Xiao-guang
    2017, 21 (6):  877-882.  doi: 10.3969/j.issn.2095-4344.2017.06.010
    Abstract ( 418 )   PDF (4258KB) ( 303 )   Save

    BACKGROUND: Neural stem cells (NSCs) hold self-renewal and multi-directional differentiation potential. NSCs differentiation into neurons in high proportion under induction conditions exhibits broad application prospect.
    OBJECTIVE: To explore the effect of basic fibroblast growth factor (bFGF)-chitosan carrier on the NSCs differentiation into neurons in vitro, and whether the differentiated neurons could form synaptic-like connection with myocytes.
    METHODS: After purification, the NSCs were co-cultured with chitosan, soluble bFGF or bFGF-chitosan carrier. After 7-day induction, the NSCs differentiation into neurons was observed by immunofluorescence staining of beta tubulin III. The NSCs differentiation into cholinergic neurons was observed through double immunofluorescence staining of ChaT and beta tubulin III. The synaptic-like connection between the neurons and myocytes was observed by triple staining of beta tubulin III and MHC.
    RESULTS AND CONCLUSION: The percentage of differentiated neurons in the bFGF-chitosan carrier group was 74%, which was significantly higher than that in the other two groups. Additionally, the synaptic-like connection formed between the differentiated neurons and myocytes. To conclude, the bFGF-chitosan carrier promotes the NSCs differentiation into neurons to form synaptic-like connection with the co-cultured myocytes.

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    Core decompression combined with beta-tricalcium phosphate bioceramics for early non-traumatic osteonecrosis of the femoral head
    He Sheng-mao, Lin Li-jun, Wang Cheng-qiang, Li Qi
    2017, 21 (6):  883-887.  doi: 10.3969/j.issn.2095-4344.2017.06.011
    Abstract ( 354 )   PDF (1092KB) ( 239 )   Save

    BACKGROUND: There are numerous laboratory reports concerning β-tricalcium phosphate (β-TCP)
    bioceramics; however, its application in the treatment of osteonecrosis of the femoral head (ONFH) is rarely reported.
    OBJECTIVE: To analyze the short-term efficacy of core decompression combined with β-TCP bioceramics in the treatment of ARCO I/II /IIIA non-traumatic ONFH.
    METHODS: Twelve patients (16 hips) suffered from ARCO I/II /IIIA non-traumatic ONFH were treated by core decompression combined with β-TCP implantation. The Harris hip scores (HHS) and radiological observation were performed before and after treatment. The HHS at the last follow-up or the HHS prior to the radiographs showing deterioration or severe complication occurrence was recorded.
    RESULTS AND CONCLUSION: All patients were followed up for 19 months averagely (11-30 months) and no fracture, infection and other complications occurred. The HHS significantly increased from (73.61±3.70) to (84.88±7.11) points after treatment (P < 0.001). The postoperative outcome was excellent in five cases with five hips, good in five cases with nine hips, mild in one case with one hip, poor in one case with one hip, and the excellent and good rate was 87.5% (14/16). The radiographs of only one case of ARCO IIC and one case of ARCO IIIA showed deterioration, and the latter was given the total hip arthroplasty. These results indicate that the core decompression combined with β-TCP implantation achieve short-term efficacy for ARCO I/II /IIIA non-traumatic ONFH.

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    Influence of different surface treatments on color of chairside porcelain veneer made of CEREC Blocs
    Sun Jia-qi, Gu Wei-ping, Chen Zhi-fei, Li Lin
    2017, 21 (6):  888-892.  doi: 10.3969/j.issn.2095-4344.2017.06.012
    Abstract ( 463 )   PDF (964KB) ( 275 )   Save

    BACKGROUND: It is convenient to fabricate porcelain veeners using chairside computer aided design/computer aided manufacture (CAD/CAM) system. However, the color of the restorations is not ideal when the veener is cemented immediately, so different surface treatments are needed.
    OBJECTIVE: To investigate the influence of different surface treatments on the color of chairside porcelain veneers made of CEREC Blocs and the color match between the porcelain veneers and teeth.
    METHODS: Five fresh extracted maxillary central incisors were selected and prepared. Twenty-five 0.6 mm porcelain veneer specimens were fabricated with Sirona CEREC Blocs by chairside CAD/CAM system, and then randomized into five groups. Untreated specimens served as control group. The other four groups were treated respectively by polishing, glazing, glazing after polishing or staining. The color parameters of specimens and the teeth were measured with ShadeEye NCC on the middle 1/3 region of labial surfaces, and color differences (ΔE) between the specimens and teeth were calculated. Data were analyzed by SPSS 19.0 software.
    RESULTS AND CONCLUSION: Compared with the control group, the L* value of the glazing, glazing after polishing and staining groups were significantly decreased (P < 0.05). The L* value of the staining group was the lowest. The a* and b* values had no significant differences between groups (P > 0.05). Compared with the control group, the ?E values of glazing, glazing after polishing and staining groups were significantly decreased (P < 0.05), and the ?E value of the staining group was the lowest. The ?L* values of glazing, glazing after polishing and staining groups were significantly lower than those of the control group (P < 0.05), and the ?L* value of the staining group was the lowest. Compared with the control group, only the ?b* value of staining group was decreased significantly (P < 0.05). The ?a* values did not differ significantly between groups (P > 0.05). These results suggest that the chairside porcelain veneers made of CEREC Blocs can obtain satisfactory aesthetic appearance by glazing and staining.

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    Clinical evaluation of nickel-titanium mechanical instruments in three different movement patterns combined with warm vertical compaction in the single-visit endodontic treatment
    Wan Na, Wang Xin-ying, Qi Lu, Yan Lei, Ma Jun-yue, Yin Yan-jiao, Gao Wen-hui, Wu Pei-ling
    2017, 21 (6):  893-898.  doi: 10.3969/j.issn.2095-4344.2017.06.013
    Abstract ( 437 )   PDF (1157KB) ( 321 )   Save

    BACKGROUND: One-visit root treatment has been widely acknowledged by clinicians. The novel nickel-titanium instruments can improve the work efficiency, treatment efficacy and comfort, which not only meet the patients’ psychological requirements, but also alleviate the doctors’ workload.
    OBJECTIVE: To evaluate the clinical evaluation of the nickel-titanium mechanical instruments in three different movement patterns combined with warm vertical compaction in the single-visit endodontic treatment.
    METHODS: 375 affected teeth from 375 patients with pulp necrosis and periapical periodontitis were randomly allotted to three groups: WaveOne reciprocating, ProTaper rotary and Twisted File Adaptive groups. All the canals of teeth were instrumented with a crown-down technique combined with ultrasonic irrigation, and then subjected to the root canal filling using warm vertical compaction.
    RESULTS AND CONCLUSION: The root canal preparation time differed significantly among groups (P < 0.001), which was the shortest in the WaveOne group, and longest in the ProTaper group. There was no significant difference in the canal obturation among groups (P > 0.05). The postoperative pain showed significant difference among groups at 24 and 72 hours (P < 0.05). At 7 days postoperatively, there was no significant difference in pain among groups (P > 0.05). These results indicate that the WaveOne can significantly improve the canal preparation and shows good molding effect; while the Twisted File Adaptive significantly reduces postoperative pain. 

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    Preparation of porous biodegradable chitosan/berberine hydrochloride composite xerogel and its antibacterial and hemostatic properties
    Wang Fang, Chen Yun-ping, Su Xiang-ping
    2017, 21 (6):  899-905.  doi: 10.3969/j.issn.2095-4344.2017.06.014
    Abstract ( 548 )   PDF (2790KB) ( 306 )   Save

    BACKGROUND: Chitosan (CS) holding a good biocompatibility, biodegradability, antibacterial property and hemostasis effect cannot only promote wound healing and tissue repair, but also exhibit sustained-control release when carrying berberine hydrochloride (Bh). Therefore it functions as an excellent antibacterial and hemostatic material.
    OBJECTIVE: To prepare the porous CS/Bh composite xerogel and observe its antibacterial and hemostatic properties.
    METHODS: The porous CS/Bh composite xerogel was prepared using freeze-drying method, and its microstructure was characterized by scanning electron microscope and Fourier transform infrared spectrometer. The biocompatibility was detected through MTT assay and the in vitro antibacterial and hemostatic properties were observed through antibacterial test and blood clotting index.
    RESULTS AND COCNLUSION: The porosity of the CS/Bh composite xerogel was 83.1%-90.5% and almost degraded after 72 hours of immersion in PBS. The in vitro antibacterial and hemostatic properties of the composite xerogel were significantly better than those of CS, which were enhanced with the Bh content increasing. Additionally, the CS/Bh (10%) composite xerogel showed the best hemostatic and antibacterial abilities in vitro. To conclude, the CS/Bh composite xerogel possesses a good biocompatibility and strong hemostatic and antibacterial abilities, which is a promising postoperative antibacterial and hemostatic material.

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    Hemostatic property and cytotoxicity of the guanidine modified chitosan
    Yao Xin-pei, Jing Miao-lei, Guan Jing
    2017, 21 (6):  906-910.  doi: 10.3969/j.issn.2095-4344.2017.06.015
    Abstract ( 515 )   PDF (1321KB) ( 321 )   Save

    BACKGROUND: Chitosan is a kind of biomaterial with good hemostatic, antibacterial and absorption properties. The guanidine modified chitosan holding better antibacterial and absorption abilities is a commonly used chemical separation material. However, its coagulation property is still unclear.
    OBJECTIVE: To evaluate the in vitro hemostatic property and cytotoxicity of the guanidine modified chitosan, and to explore its availability as a hemostatic material.
    METHODS: The guanidine modified chitosan was synthesized with the raw materials of chitosan and arginine, and the coupling agents of EDC and NHS. The coagulation ability was evaluated preliminarily through the whole blood coagulation time, and three in vitro coagulation indexes (activated partial thromboplastin time, prothrombin time and thrombin time). The guanidine modified chitosan extracts were co-cultured with the mouse fibroblasts, and then the cell growth was observed by MTT assay and fluorescence microscope.
    RESULTS AND CONCLUSION    : The guanidine modified chitosan shortened the whole blood coagulation time, suggesting its hemostatic property. In vitro coagulation results indicated that the guanidine modified chitosan exerted the effect not through the traditional endogenous and extrinsic coagulation pathways. Guanidino group has not been proved to be hemostatic, so the chitosan may be the effective component. MTT assay showed that the cell proliferation rate was 87.8% and the toxicity level was grade 1. Fluorescent staining observed abundant live cells, and few dead cells, indicating that the guanidine modified chitosan exhibits low cytotoxicity. 

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    Comparative study of drug release in vitro of polylactic acid/polyglycolic acid coated triple anti-tuberculosis drug-loading artificial bone
    Wang Qian, Liu Hai-tao, Shi Jian-dang, Wang Zi-li, Geng Guang-qi, Niu Ning-kui, Wang Jie, Yan Jun-fa
    2017, 21 (6):  911-916.  doi: 10.3969/j.issn.2095-4344.2017.06.016
    Abstract ( 404 )   PDF (2398KB) ( 251 )   Save

    BACKGROUND: Calcium sulfate/polyamino acid artificial bone material carrying triple anti-tuberculosis drugs (isoniazide, rifampicin, pyrazinamide) has good release characteristics and antibacterial activity, but its shortcomings also exist for the phenomenon of burst, due to a faster degradation of calcium sulfate.
    OBJECTIVE: To observe the effect of polylactic acid/polyglycolic acid copolymer (PLGA) coating on drug release behavior in vitro of triple anti-tuberculosis drugs containing calcium sulfate/polyamino acid bone.
    METHODS: According to the selected optimum recipe, we prepared drug-loading artificial bones and non-drug-loading artificial bones in a dark place. After infiltrating in PLGA, drying and sterilizing, we soaked them in simulated body fluid for drug release experiments. Through high performance liquid chromatography method, the concentrations of isoniazide, rifampicin, pyrazinamide released at different times were observed.
    RESULTS AND CONCLUSION: For triple anti-tuberculosis drugs drug artificial bone with no PLGA coating, the drug release of isoniazide accounted for 91.75% of the total drug loading capacity at 7 weeks; the drug releases of rifampicin and pyrazinamide respectively accounted for 88.34% and 49.35% of their own total drug loading capacity at 8 weeks. For triple anti-tuberculosis drug artificial bone with PLGA coating, the drug release of isoniazide accounted for 43.51% of the total drug loading capacity at 17 weeks; the drug releases of rifampicin and pyrazinamide respectively accounted for 15.92% and 48.42% of their own total drug loading capacity at 16 weeks. For blank control group, the drug peak was not noticed in effective detection period. These findings indicate that PLGA coated triple anti-tuberculosis drug-loading calcium sulfate/polyamino acid artificial bone can control drug release, increase the release period and maintain a high level of drug concentration in local lesion for a long time, so as to give full play to the anti-tuberculosis function of triple anti-tuberculosis drug loading artificial bone.

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    Mechanical properties of sciatic nerve injury after repaired with poly(lactic acid-glycolic acid) scaffold
    Li Zheng-wei, Lv Xue-man, Li Xin-ying, Li Ya-jun, Luo Min
    2017, 21 (6):  917-922.  doi: 10.3969/j.issn.2095-4344.2017.06.017
    Abstract ( 409 )   PDF (1123KB) ( 292 )   Save

    BACKGROUND: The tensile and stress-relaxation mechanical properties of sciatic nerve injury after repaired with autologous nerve and poly(lactic acid-glycolic acid) (PLGA) scaffold are rarely reported.
    OBJECTIVE: To analyze the tensile and stress relaxation characteristics of sciatic nerve injury after the transplantation of autologous nerve and PLGA scaffold.
    METHODS: Sixty sciatic nerves were extracted from the fresh cadavers dead within 24 hours, processed into 35 mm samples, and were then randomly divided into three groups. The nerve samples in control group received no intervention; the nerves in artificial and autologous groups were modeled into 20 mm defects, followed by repaired with PLGA scaffold and autologous nerve, respectively. Afterwards, the tension and stress-relaxation tests were performed in each group.
    RESULTS AND CONCLUSION: The stress in each group descended fast at the first 600 seconds, then descended slowly and was closed to the horizontal level until 7 200 seconds, and the stress-relaxation curves in each group were in logarithmic decrease. The order of the elastic limit load, elastic limit stress, maximum load, maximum stress, elastic limit strain and maximum strain during tension was as follows: control group > artificial group > autologous group (P < 0.05). Our results indicate that the PLGA scaffold holds good tension and stress-relaxation properties, which meets the mechanical requirements of the biomaterials used for sciatic nerve repair.

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    Transferrin-labeled magnetolipsomes: preparation and magnetic resonance imaging in vitro
    Chen Wei-cui, Liu Shu-yi, Lin Ai-hua, Liu Xian
    2017, 21 (6):  923-927.  doi: 10.3969/j.issn.2095-4344.2017.06.018
    Abstract ( 484 )   PDF (1090KB) ( 259 )   Save

    BACKGROUND: Transferrin (Tf) is one suitable ligand to be conjugated to drug delivery systems to achieve site-specific targeting and desired therapeutic effect, due to its specific binding to transferrin receptors (TfR), and high expression on the surface of tumor cells. Contrast agents are also modified with Tf to achieve specific tumor imaging.
    OBJECTIVE: To prepare Tf-labeled magnetoliposomes (MLs), and characterize their utility as TfR targeted MR specific contrast agent in vitro.
    METHODS: MLs and Tf-MLs were prepared by lipid film hydration method and covalent coupling method, respectively. Tf-MLs were characterized by their mean size, zeta potential, polyindex, r2 relaxivity, Tf-binding efficacy and cytotoxicity. In vitro MRI contrasting properties of the suspended nanoparticles incubated with HepG2 cells were determined.
    RESULTS AND CONCLUSION: The mean diameter, polydisperisity index, zeta potential and r2 relexivity of Tf-ML were 95.1 nm, 0.21, -1.25 mv and 94.62 mmol-1/s, respectively. The coupling efficiency was calculated and the values obtained were 59.4 μg Tf/μmol phospholipid corresponding to about 27 molecules of Tf-MLs. After a 2-hour incubation with rhodamine-labeled Tf-MLs, rhodamine fluorescence was detected intensively in the plasma membrane and the cytoplasm of the TfR-overexpressing HepG2 cells. In contrast, Tf-ML showed little binding in MCF-7 cells that had low TfR level. HepG2 cells incubated with Tf-ML showed much higher intracellualar iron density than incubated with non-targeted MLs. In vitro MR T2WI of cells demonstrated the centrifuge tube containing HepG2 cells incubated with Tf-MLs produced a lower visible signal intensity than that treated with non-targeted MLs. Tf-MLs showed their potentials such as high r2 relaxivity, specific binding ability characteristics. These results suggest the availability of Tf-MLs to serve as a targeted contrast agent.  

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    Current situations of sterile and implantable medical device manufacturing in Sichuan Province: an investigation in 31 production enterprises 
    Zhou Jing, Ye Xiang, Jiang Xue-hua
    2017, 21 (6):  928-933.  doi: 10.3969/j.issn.2095-4344.2017.06.019
    Abstract ( 394 )   PDF (1065KB) ( 262 )   Save

    BACKGROUND: The Specification of Quality Management for Medical Device Production (for Trial Implementation) issued by the China Food and Drug Administration (CFDA) on December 16, 2009 was demanded to be initially implemented in medical device manufacturers with a higher risk in sterility and implant before January 1, 2011. The revised version was published on December 29, 2014 and came into effect on March 1, 2015.
    OBJECTIVE: To put forward specific suggestions through analyzing the status of 31 sterile implantable medical device manufacturers in Sichuan Province and the corresponding implementation situation of the specification for trial implementation.
    METHODS: The relevant data of these 31 manufacturers were collected through the quality management system assessment, supervision and inspection, flight inspection and questionnaire survey. And the data were analyzed statistically.
    RESULTS AND CONCLUSION: The overall size of medical device manufacturers in Sichuan Province is small. There are still some other problems, such as no advanced equipment, low quality of employees, lack of funds and inappropriate management, in these manufacturers. Considering these, we have given some guiding recommendations from the aspects of production and supervision.

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    Effect of small interfering RNA delivery using galactosylated chitosan-graft-polyethylenimine on MRE11 gene expression in drug-resistant hepatocellular carcinoma BEL7402/5-Fu cells
    Liu Yun, Pan Jie, Dong Wei, Hui Jing, Li San-hua, Fan Fang, Zhu Xin-ting
    2017, 21 (6):  934-939.  doi: 10.3969/j.issn.2095-4344.2017.06.020
    Abstract ( 442 )   PDF (1582KB) ( 236 )   Save

    BACKGROUND: Chitosan is a kind of common non-viral vector characterized by good biocompatibility, biodegradability and low toxicity. However, it usually needs structural modification via derivatization due to its weak gene delivery ability.
    OBJECTIVE: To observe the ability of galactosylated chitosan-graft-polyethylenimine (GAL-CHI-g-PEI) delivering small interfering RNA (siRNA) on drug-resistant hepatocellular carcinoma BEL7402/5-Fu and its effect on the expression of meiotic recombination 11 (MRE11).
    METHODS: BEL7402/5-Fu cells or human hepatocytes HL-7702 were co-cultured with 0, 10, 20, 40, 80 and 100 μg/mL GAL-CHI-g-PEI or chitosan-PEI for 24 hours, and then the cell viability was detected. The composite transfection particles were prepared by mixing GAL-CHI-g-PEI with siRNA-FAM at the mass ratio of 0, 2, 4, 8, 16 and 32, respectively. The next experiments were performed based on BEL7402/5-Fu cells transfected with the compound transfection particles, and the optimal mass ratio and transfection time were selected according to the efficiency of transfection at 18, 72 and 96 hours afte transfection. At 48 hours after BEL7402/5-Fu cells transfected with compound transfection particles, GAL-CHI-g-PEI and siRNA, respertively, the expressions of MRE11 mRNA and protein were detected in comparison with untransfected cells as controls.
    RESULTS AND CONCLUSION: Compared with chitosan-PEI, GAL-CHI-g-PEI demonstrated lower toxicity, and still showed low cytotoxicity when the mass concentration reached 100 μg/mL. The transfection efficiency was over 95% and the cell entry efficiency was extremely high when the mass ratio of GAL-CHI-g-PEI to siRNA-FAM was 4 and 8, respectively, with the optimal transfection effect at 48 hours after transfection. Therefore, the mass ratio in the subsequent experiments was set to 8. The expressions of MRE11 mRNA and protein in the composite transfection group were lower than those in the GAL-CHI-g-PEI, siRNA and control groups (P < 0.05). These results suggest that the effective delivery of siRNA and the silencing of the MRE11 gene in BEL7402/5-Fu cells can be achieved by GAL-CHI-g-PEI.

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    Biocompatibility of electrospun carbon nanotubes/poly(L-lactic acid) nanofiber scaffolds with mouse neural stem cells
    Lin Cheng-kai, Rong Li-min, Liu Bin
    2017, 21 (6):  940-945.  doi: 10.3969/j.issn.2095-4344.2017.06.021
    Abstract ( 379 )   PDF (2481KB) ( 318 )   Save

    BACKGROUND: Poly(L-lactic acid) (PLLA) scaffold is a kind of widely used biomaterial in tissue engineering. However, low hydrophilicity and lack of surface cell recognition site of PLLA hinder its further application.
    OBJECTIVE: To study the biocompatibility of multi-walled carbon nanotubes/PLLA (MWCNTs/PLLA) nanofiber scaffolds with mouse neural stem cells in vitro.
    METHODS: Mouse neural stem cells were isolated. Then we used electrospinning to fabricate PLLA nanofibers and modified them with multi-walled carbon nanotubes. We assessed their biocompatibility with passage 3 mouse neural stem cells in vitro.
    RESULTS AND CONCLUSION: Scanning electron microscope showed that the neural stem cells could survive on both scaffolds. No cytotoxic effects were detected on both scaffolds by Cell Counting Kit-8 detection. The adhesion and proliferation abilities of neural stem cells on the MWCNTs/PLLA scaffold were significantly greater than those on the PLLA scaffold. Neural stem cells were found grow well and have normal morphology on both scaffolds under scanning electron microscope and by Hoechst 33342 staining. Besides, immunofluorescence staining showed MWCNTs/PLLA could promote neural stem cells to differentiate into mature neurons and neurites grew along with the nanofiber scaffold. In conclusion, the MWCNTs/PLLA nanofiber scaffold has better properties than the PLLA for transplanted cells and provides a good growth carrier for neural stem cells to be induced to differentiate into neurons, which is expected to have a great potential of applications in nerve tissue engineering. 

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    Homemade sirolimus-eluting stent with biodegradable coating: feasibility and price advantage
    An Ya-fang
    2017, 21 (6):  946-951.  doi: 10.3969/j.issn.2095-4344.2017.06.022
    Abstract ( 599 )   PDF (1204KB) ( 257 )   Save

    BACKGROUND: The homemade sirolimus-eluting stent with biodegradable coating (Tivoli stent) is cheaper than the imported zotarolimus-eluting stent (Endeavor stent) by half. Tivoli stent has been widely applied in clinic gradually, and its safety and efficacy will be recognized. 
    OBJECTIVE: To explore the feasibility and price advantage of the Tivoli stent versus Endeavor stent.
    METHODS: 110 patients with coronary heart disease in Tianjin Occupational Diseases Prevention and Therapeutic Hospital (Tianjin Workers’ Hospital) from January 2006 to January 2016 were selected and randomly allotted to two groups, followed by treated with Tivoli or Endeavor stents, respectively. The procedural success rate, the serum level of C-reactive protein before and 1 week after treatment, coronary angiographic results at 8 months after treatment, as well as the incidence of major adverse cardiac and stent thrombosis events during the 270-day follow-up were observed.
    RESULTS AND CONCLUSION: The successful rate of stent implantation was 100% in both groups. The serum level of C-reactive protein in the patients subjected to Tivoli stent before and 1 week after operation showed no significant difference (P > 0.05). The rate of angiographic follow-up in the Tivoli and Endeavor groups was respectively 93% (52/56) and 93 (50/54), and the rate of in-stent stenosis was 11% (8/52) and 3% (2/50) (P=0.370) at 8 weeks postoperatively. All the patients were followed up for 270 days, and there was no death, myocardial infarction or stent thrombosis; the incidence of major adverse cardiac events due to the target lesion revascularization was 11% (6/56) in the Tivoli group and 7% (4/54) in the Endeavor group( P=1.000). These results suggest that the short- and mid-term efficacy, biocompatibility and safety of Tivoli stents are similar with those of Endeavor stents, so the price advantage stands out.

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    Biocompatibility and quantitative analysis of oral bone implant materials in vivo using synchrotron radiation-based micro-computed-tomography: study protocol for a
    randomized controlled animal experiment
    Sun Lian-lian, Wang Zhi-xing
    2017, 21 (6):  952-956.  doi: 10.3969/j.issn.2095-4344.2017.06.023
    Abstract ( 386 )   PDF (941KB) ( 240 )   Save

    BACKGROUND: At present, bone substitute filling is mainly used for bone defect repair. In order to understand the effect on bone defect repair, it is necessary to look into the microstructure changes of bone defects after bone substitute implantation. Synchrotron radiation-based micro-computed-tomography (SR-μCT) can be used to make high-resolution, high-resolution three-dimensional imaging without slicing and dyeing, and has high scientific and clinical value.
    OBJECTIVE: To explore the feasibility of SR-μCT in micron-level bone osseointegration examination in oral medicine.
    METHODS: This randomized controlled animal experiment was completed at the Fifth Central Hospital of Tianjin, Tianjin, China. A rabbit model of mandibular defect was made in 24 male New Zealand white rabbits. The model rats were randomly divided into four groups and received autologous bone, Bio-oss bone meal, β-tricalcium phosphate powder and no implantation (negative control group) in the defective area, respectively. Bone samples, including the defect area and the surrounding normal bone tissue, were taken at 2, 4, 8 weeks postoperatively for SR-μCT examination, followed by histopathological examination, in order to observe the repairing effects of different types of bone implant materials from different angles. The study protocol has been approved by the Ethics Committee of the Fifth Central Hespital of Tianjin in China. The study procedures were completed in accordance with the Guidance Suggestions for the Care and Use of Experimental Animals of China and the guidelines of the National Institutes of Health, USA.
    RESULTS AND CONCLUSION: In this study, SR-μCT could be used to observe the bone microstructure and osseointegration with no damage to samples to collect accurate quantitative data, including bone volume, number of bone trabeculae and bone mineral density. Therefore, SR-μCT can fully analyze the biocompatibility of bone implant material in vivo, give insight into the micron-level changes of different types of bone implant materials in the bone defect, thereby providing experimental evidence to improve bone defect healing.

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    Correct measurement of the posterior wall size of adult male inguinal hernia used for herniorrhaphy
    Tu Zhi-qiang, Wang Wei-xing
    2017, 21 (6):  957-961.  doi: 10.3969/j.issn.2095-4344.2017.06.024
    Abstract ( 442 )   PDF (1138KB) ( 239 )   Save

    BACKGROUND: The mesh size used for herniorrhaphy mainly depends on clinicians’ experience, which is less reliable.
    OBJECTIVE: To obtain the mesh size by measuring the posterior wall of inguinal hernia in Chinese adult men undergoing Rutkow surgery, and to assess the postoperative effect.
    METHODS: The posterior wall size of inguinal hernia in 180 Chinese adult male patients undergoing tension-free hernioplasty was measured, and then the optical mesh size was calculated. All patients were equivalently randomized into two groups, followed by subjected to Rutkow surgery according the calculated mesh size (experimental group) or subjective size (control group). Clinical indexes, the incidence of complications and recurrence rate were compared between groups.
    RESULTS AND CONCLUSION: The distance of pubic tubercle to internal oblique inguinal ligament starting point was (6.03±0.58) cm; the vertical distance of the highest point on the edge of the arcuate to inguinal ligament was (3.02±0.32) cm; therefore, the length of mesh should be larger than (13.04±0.74) cm, and width larger than (5.88±0.52) cm. The time of off-bed, dieting and hospitalization in the experimental group were significantly less than those in the control group (P < 0.05); the time of operation and recovery of normal activities showed no significant difference between groups (P > 0.05). The rates of postoperative complication and recurrence in the experimental group were significantly lower than those in the control group (P < 0.01). These results suggest that after measuring the posterior wall size of inguinal hernia, the Rutkow used for inguinal hernia repair, obtains desired treatment outcomes with low incidence of complications and recurrence.

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    Peripheral nerve injury and regeneration: application and progress of novel nerve scaffolds
    Quan Qi, Chang Biao, Liu Ruo-xi, Sun Xun, Wang Yu, Lu Shi-bi, Peng Jiang, Zhao Qing
    2017, 21 (6):  962-968.  doi: 10.3969/j.issn.2095-4344.2017.06.025
    Abstract ( 509 )   PDF (1210KB) ( 772 )   Save

    BACKGROUND: Autologous nerve grafts are the gold standard for large segment peripheral nerve injury, but in view of its limitations, scientists are researching for novel nerve guidance conduits.
    OBJECTIVE: To overview the new view in peripheral nerve injury, key cells associated with axonal regeneration, and application of nerve guidance conduits.
    METHODS: The first author retrieved PubMed database for relevant articles about tissue-engineered nerve scaffold published from 2001 to 2016 using the English keywords of “peripheral nerve injury, peripheral nerve regeneration，nerve scaffold”. Finally, 76 articles were enrolled based on the inclusion and exclusion criteria.
    RESULTS AND CONCLUSION: Peripheral nerve repair mainly focuses on how to make the regenerative nerve grows “fast” and “accurate”. In the future, we should focus on not only developing better biocompatible materials, but also optimizing the design to simulate the nerve regeneration microenvironment at molecular, cell and tissue levels. The nerve scaffolds used for nerve regeneration not only exert a supporting mechanical effect, but also act as conduct electricity and sustained release of cytokine gradient. Bionics design should be further expanded from the morphology to the spatial changes of cytokines and bioelectric stimulation.

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    Research advance in the osteointegration of surface bioactive coating on titanium alloys
    Liu Guan-cong, Li Rui-yan, Liang Hao-jun, Qin Yan-guo
    2017, 21 (6):  969-974.  doi: 10.3969/j.issn.2095-4344.2017.06.026
    Abstract ( 465 )   PDF (988KB) ( 315 )   Save

    BACKGROUND: Titanium alloy, a commonly used bone biomaterial, holds good biocompatibility and proper mechanical properties, but without osteointegration ability. Surface bioactive coating of titanium alloy can overcome such problems.
    OBJECTIVE: To review the application progress of surface bioactive coating on titanium alloys, and to explore the mechanism underlying its osteogenic induction.
    METHODS: PubMed and CNKI databases were searched for literatures concerning surface bioactive coating on titanium alloys published from January 2000 to March 2016, using the keywords of “titanium, titanium alloys, coating, surface modification, bone” in English and Chinese, respectively. Through preliminary analysis, 42 eligible articles were selected.
    RESULTS AND CONCLUSION: The surface modification method has undergone the transition from surface roughening, oxidation, acidification treatment to the most widely used biomimetic coating technology. The surface biomimetic coatings of titanium alloys mainly include hydroxyapatite, bioactive glass, zeolite, which have been developed from a single coating to the composite coatings and gradient coatings. What’s more, the bioactive factor or/and metal ions in the coating can improve the osteointegration of surface coating. Surface modification for titanium alloys is a complex process, during which, both the osteogenesis ability and the bonding strength between the coating and its substrate cannot be ignored. Improving the fabrication method of existing coatings and exploring new materials of biomimetic coatings are critical to achieve a high-quality surface coating modification.

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    Implantable artificial pacemaker: materials and material-related complications
    Chen Yao, Hao Yan-li
    2017, 21 (6):  975-979.  doi: 10.3969/j.issn.2095-4344.2017.06.027
    Abstract ( 797 )   PDF (1186KB) ( 198 )   Save

    BACKGROUND: The implantable artificial pacemaker that needs long-term wear is in direct contact with human body tissue, and thus, biocompatibility of the materials is very important.
    OBJECTIVE: To investigate the material progress and material-related complications of implantable artificial pacemakers.
    METHODS: Articles related to implantable artificial pacemaker materials and related complications were searched in Wanfang database and PubMed database from 2000 to 2015. The keywords were “pacemaker; materials; pacemaker leads; pacemaker electrode; complication” in Chinese and English, respectively. Finally, 27 articles were included and summarized.
    RESULTS AND CONCLUSION: The implantable artificial pacemakers are in direct contact with the body tissues through the titanium alloy shell covering the pulser, the electrode wire covering the silicone, polyurethane, epoxy resin, and the electrode materials (including carbon, platinum-iridium alloy, Elgilog alloy). These materials have good physical and chemical properties as well as good cytocompatibility, electrophysiological compatibility and blood compatibility with the human body that have been confirmed in the past decades. However, material-related complications often occur, such as contact dermatitis, wire breakage, dislocation, cardiac perforation, venous thrombosis and tricuspid regurgitation along the wire, capsular infection and hematoma when placing the pulser. With the rapid development of today’s microelectronic technology, research on the modification of pacemaker materials and the pacing system has been ongoing and has made considerable progress. Moreover, wireless pacemaker development and clinical application may be the future direction of development.

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    Effect of expanded polytetrafluoroethylene prosthesis in rhinoplasty: study protocol for a randomized controlled clinical trial
    Li Jian-min
    2017, 21 (6):  980-984.  doi: 10.3969/j.issn.2095-4344.2017.06.028
    Abstract ( 400 )   PDF (998KB) ( 224 )   Save

    BACKGROUND: Costal cartilage, auricular cartilage, materials for teeth and silica gel have been widely applied in rhinoplasty, but consequent adverse events, such as rejection, prosthesis displacement and implanted skin redness make the outcomes far from satisfaction.
    OBJECTIVE: To explore the effect of expanded polytetrafluoroethylene prosthesis for lower dorsum with small nasal septum.
    METHODS/DESIGN: This was a prospective, single-central, randomized, and open-label study that finished in the Qinghai University Affiliated Hospital, China. 100 patients hospitalized in the Department of Otorhinolaryngology for rhinoplasty between January 2014 and June 2015 were enrolled, and randomized into experimental and control groups (n=50 per group). The experimental group was subjected to the polytetrafluoroethylene prosthesis implantation, while the control group received the silica gel implantation. All patients were followed up for 12 months. The primary outcome measure was the postoperative satisfaction at 12 months. The secondary outcome measures were the changes of the nasal internal structure indexes, ultrasonic results of the nasal internal soft tissues and the incidence of adverse events. This study was approved by the Ethics Committee of the Qinghai University Affiliated Hospital and in accordance with the Declaration of Helsinki, formulated by the World Medical Association. All participants had signed the informed consents prior to participation in the study.
    DISCUSSION: Polytetrafluoroethylene prosthesis and silica gel both exhibit high biosafety in rhinoplasty. Compared with silica gel, the polytetrafluoroethylene prosthesis can effectively adjust the nasal appearance mini-invasively and obtain satisfactory outcomes; therefore, it is expected to be a substitute of filling materials applied in nasal plastic surgery,

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