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08 August 2018, Volume 22 Issue 22 Previous Issue    Next Issue

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Preparation of magnesium-doped brushite by sintering method Jia Wan-ping, Dong Wei, Peng Hong-feng, Xu Yan-li, Wang Hong-mei, Liang Li-shuo, Qi Meng-chun, Liang Yong-qiang 2018, 22 (22):  3445-3450.  doi: 10.3969/j.issn.2095-4344.0781 Abstract ( 343 )   PDF (809KB) ( 133 )   Save BACKGROUND: As an absorbable calcium phosphate cement and bone substitute implant, calcium phosphate stone has become the focus of bone tissue engineering research, but some deficiencies in its properties have greatly limited its clinical application. The scholars try to add some elements to modify the calcium phosphate stone, in order to enhance the mechanical properties, prolong the curing time and improve the osteogenesis. OBJECTIVE: To make magnesium-doped brushite by adding magnesium ions to beta-tricalcium phosphate with sintering method and to detect the feasibility of magnesium-doped brushite as a bone substitute by detecting physical and chemical properties and ability of repairing bone defects. METHODS: Magnesium-doped brushite in different molar ratios of Mg/(Mg+Ca) (0%, 6.67% and 26.67%) was prepared using sintering method. Morphological structure and compressive strength of the prepared bone cement were detected using scanning electron microscope and universal material test machine, respectively. Magnesium-doped brushite extracts (0%, 6.67%, 26.67%) were added into rabbit anticoagulant to perform a hemolytic test. Twenty-four rabbits were used to make bilateral tibial bone defect models, and then rabbit models were divided into four groups: three groups were implanted with 0%, 6.67%, and 26.67% magnesium-doped brushite bone cement, and the blank group received no treatment. X-ray examinations were performed at 4 and 8 weeks after implantation. RESULTS AND CONCLUSION: Under the scanning electron microscopy, the 0% magnesium-doped brushite cement had a tightly packed plate-like shape and a small amount of granules with less pores; the 6.67% magnesium-doped brushite cement presented with irregular lumps and short rods; and the 26.67% magnesium-doped brushite cement was lumpy, spherical and granular. The magnesium-doped brushite cements (0%, 6.67%, 26.67%) had compressive strengths of 31.99, 26.38, 24.44 MPa, respectively. The hemolysis rate of all the brushite bone cements was less than 5%. X-ray results showed that at the 4th week after implantation, the defect margin in the blank group was ruled without new bone formation; in the 0% magnesium-doped brushite group, the bone cement was dissolved at the margin, and a few high-density shadows were detected at the junction between bone defects and the cement; in the 6.67% magnesium-doped brushite group, the bone cement was mostly dissolved and there were a large amount of new bone tissues; in the 26.67% magnesium-doped brushite group, the bone cement was dissolved at the margin, and there were high-density shadows in the center of the bone cement with less new bone formation. At 8 weeks after implantation, there were new bone deposits at the two ends of the blank group; the new bone was wedge-shaped in the 0% magnesium-doped brushite group; the bone defect in the 0% magnesium-doped brushite group was basically filled with new bone tissues, and the bone cortex was continuous; and in the 26.67% magnesium-doped brushite group, the new bone served as a bridge to link the broken bone ends with poor plasticity. These findings indicate that 6.67% magnesium-doped brushite cement has good mechanical properties and osteogenic effects. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Antibacterial properties of novel magnesium alloys in vivo Wang Zhan, Yang Jun, Li Jian-jun 2018, 22 (22):  3451-3455.  doi: 10.3969/j.issn.2095-4344.0785 Abstract ( 427 )   PDF (598KB) ( 128 )   Save BACKGROUND: As a new biodegradable metallic biomaterial, magnesium alloys with good bio-safety, degradability, mechanical strength and biocompatibility have been noticed in clinical practice. Recent studies mainly focus on the process and mechanism of degradation, biological safety and biocompatibility of magnesium alloys. Little is reported on the antibacterial properties of magnesium alloys. OBJECTIVE: To observe the antibacterial properties of novel magnesium alloys (Mg3Zn, Mg3Zn1Ag, Mg3Zn3Ag) in vivo. METHODS: The 12 of 15 Sprague-Dawley rats were implanted with different materials (Mg, Mg3Zn, Mg3Zn1Ag, Mg3Zn3A; three rats for each material) in the tibia of the hind limbs, respectively. Then, Staphylococcus aureus solution was injected at the incision of each rat. The remaining rats only given injection of Staphylococcus aureus solution were taken as controls. The above-mentioned treatments were repeated in another 15 Sprague-Dawley rats except injection of Escherichia coli rather than Staphylococcus aureus. The body temperature of the rats was continuously monitored within 14 rats after implantation. At post-implantation days 1, 3, 5, 10 and 14, the white blood cell count was measured. At post-implantation day 14, the rats were sacrificed and the secretions and tissues of the surgical site were taken for bacterial identification. RESULTS AND CONCLUSION: The body temperature of all the rats increased after bacterial infection, but the temperature of the rats implanted with magnesium and magnesium alloys was always lower than that in the two control groups given pure bacterial infection. Moreover, the increment in body temperature of the rats declined with the increasing Ag content in magnesium alloys. Routine blood test results showed that the number of white blood cells increased after bacterial infection, while the number of white blood cells in the magnesium and magnesium alloy groups peaked at 5 days after implantation, and then significantly reduced as compared with the control groups       (P < 0.05). Furthermore, the increment in the cell number was reduced with the increasing Ag content in magnesium alloys. Bacterial culture results showed that S.aureus(+) in the Staphylococcus aureus infection group and E.coli(+) in the Escherichia coli infection group. To conclude, novel magnesium alloys exert marked antibacterial effects on Staphylococcus aureus and Escherichia coli. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Preparation and performance evaluation of a biomimetic scaffold derived from the extracellular matrix of a native growth plate Li Wen-chao, Xu Rui-jiang, Huang Jing-xiang, Li Hao-yu, Cai Gang, Chen Hui 2018, 22 (22):  3456-3460.  doi: 10.3969/j.issn.2095-4344.0782 Abstract ( 314 )   PDF (694KB) ( 143 )   Save BACKGROUND: The extracellular matrix from the growth plate contains abundant sources of collagens, proteoglycan and signaling molecules. These components and characteristic are very similar to the natural growth plate tissue, and therefore, it is an ideal material to construct tissue-engineered growth plate. OBJECTIVE: To prepare the columnar biomimetic scaffold using native growth plate extracellular matrix and to evaluate the scaffold performance. METHODS: The knee joint of fetal bovine was separated and purified by pulverization technology in moist environment, differential centrifugation and organic solvent to obtain extracellular matrix microfilaments. Then the extracellular matrix microfilaments were treated by directed crystallization technology, freeze drying and physicochemistry crosslinking method in order to prepare the extracellular matrix biomimetic scaffold. The scaffold was evaluated by scanning electron microscope for internal structure and pore size, porosity and swelling rate of water absorption as well as by histological observation. RESULTS AND CONCLUSION: The extracellular matrix microfilaments were fibriform with the even and regular shape shown by hematoxylin-eosin staining, and were also positive for toluidine blue, Sarranine O and collagen II staining, indicating the existence of active components of the growth plate in the scaffold. (2) The scaffold under the scanning electron microscope showed porous honeycomb structure on the transverse section plane with uniform pore size and regular shape, while there was a parallel arrangement of columnar structure on the longitudinal section plane of the scaffold with well-distributed and mutual communication, and scaffold fibers on the outer wall were longitudinally arranged, which imitated the columnar structure from the native growth plate. The pore diameter of scaffold was (117.5±15.37) μm, the porosity was (92.05±1.54)% and the water absorption was (95.95±1.07)%. To conclude, the columnar scaffold from the extracellular matrix of the growth plate imitates the native growth plate in terms of components and structures.      中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Changes in cytoskeleton proteins and mechanical properties of the cells on soft substrates Hou Tian, An Mei-wen, Wang Li 2018, 22 (22):  3461-3466.  doi: 10.3969/j.issn.2095-4344.0882 Abstract ( 360 )   PDF (664KB) ( 126 )   Save BACKGROUND: Preliminary studies have shown that substrate hardness is directly involved in cell regulation, but this effect can be hindered via suppression of myosin expression. Therefore, the effect of substrate hardness on myosin expression needs to be further quantified. OBJECTIVE: To quantify the effect of substrate hardness on the distribution and movement rate of myosin II as well as on the distribution of actin fibers. METHODS: Polyacrylamide gels were used to prepare substrates with hardness of 1, 10, 150 kPa. Cervical cancer were Hela cells stably transfected with fluorescent myosin II, and these transfected cells were incubated onto the substrates of different hardness. The fluorescence distribution of fluorescent myosin II along the long axis of Hela cells on the substrates of different hardness was measured. The movement rate of fluorescent myosin II was determined by fluorescence photobleaching recovery technique. F-actin distribution was observed using fluorescent staining. The elastic modulus of single cervical cancer cells spreading on different substrates was determined using micropipette aspiration technique. RESULTS AND CONCLUSION: For the cells growing on the 150 kPa substrate, the highest intensity of fluorescent myosin II was located on the cell edge. For the cells on the substrates of 1 and 10 kPa, there was a reduced distribution of fluorescent myosin II on the cell edge. For the cells on the 150 kPa substrate, the recovery rate of fluorescent myosin II was significantly faster than that on the substrates of 1 and    10 kPa. Actin fibers in the cells growing on the substrates of 1, 10 and 150 kPa shared similarity in the overall fluorescence intensity. The elastic modulus of Hela cells on the substrate of 150 kPa was significantly higher than that on 1 kPa and 10 kPa substrates. Experimental results show that substrate hardness can significantly alter the regional effects of cytoskeletal proteins such as myosin and actin, and affect the cell status of cancer cells in different microenvironments. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Low-temperature synthesis and stabilization of carboxymethyl chitosan stabilized amorphous calcium phosphate Wang Ping-ting, Qi Xing-ying 2018, 22 (22):  3467-3473.  doi: 10.3969/j.issn.2095-4344.0893 Abstract ( 292 )   PDF (1027KB) ( 225 )   Save BACKGROUND: Amorphous calcium phosphate can serve as a precursor phase of nano-hydroxyapatite and the storage source for calcium and phosphate. However, the stability of amorphous calcium phosphate is greatly influenced by synthetic environments, which is easy to trigger a phase transition. OBJECTIVE: To stabilize amorphous calcium phosphate by carboxymethyl chitosan (CMCS) and to investigate the lowest threshold of CMCS with stabilizing capacity and the effects of aging time on stabilization period. METHODS: CMCS-amorphous calcium phosphate precipitates in different CMCS/Ca molar ratios (1:1, 1:2, 1:3, 1:4, 1:5) were synthesized at 4 ℃. Their microstructures were observed by scanning electron microscopy (SEM) and chemical compositions were analyzed by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The lowest threshold of CMCS/Ca with stabilizing capacity was thus acquired. The stable complexes at this lowest threshold were investigated by thermogravimetric analysis and differential scanning calorimetry to determine the content of amorphous calcium phosphate. CMCS-amorphous calcium phosphate complexes with the lowest threshold of CMCS/Ca were then synthesized under different aging times (10, 30, 60, 90 minutes) and dissolved in simulated body fluid. Effects of aging time on stabilization period were discussed following the investigation on the phase transition of amorphous calcium phosphate by SEM and XRD.  RESULTS AND CONCLUSION: (1) According to the results from XRD and FTIR, CMCS-amorphous calcium phosphate precipitates were amorphous when CMCS/Ca ≥ 1:3. (2) According to the findings of SEM, plenty of evenly distributed amorphous calcium phosphate particles were found in the precipitates when CMCS/Ca ≥ 1:3. (3) The lowest threshold of CMCS/Ca used for synthesizing the stable CMCS-amorphous calcium phosphate complexes at 4 ℃ reached to 1:3, and the actual content of amorphous calcium phosphate was 63.63%. (4) According to the results from XRD and SEM, the CMCS-amorphous calcium phosphate complexes dissolved in the simulated body fluid were amorphous under 10, 30, 60 minutes of aging and the corresponding stabilization period was 2, 6, 8 hours, respectively, while the amorphous complexes became crystals under 90 minutes of aging. All these findings indicate that the lowest threshold of CMCS/Ca with the stable CMCS-amorphous calcium phosphate in a low temperature is 1:3. When synthesized with this lowest threshold of CMCS/Ca, the stabilization period of amorphous calcium phosphate is positively correlated with aging time and varies from 2 to 8 hours. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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IPS e.max ceramic veneers versus VITA VM9 porcelain laminate veneers Jin En-long, Wu Da-hong, Yan Liang, Wang Jue, Jiao Yan-jun 2018, 22 (22):  3474-3479.  doi: 10.3969/j.issn.2095-4344.0779 Abstract ( 913 )   PDF (711KB) ( 441 )   Save BACKGROUND: Porcelain veneer is a minimally invasive method for tooth aesthetics, but repairing effects of various porcelain veneers have yet to be compared. OBJECTIVE: To compare the therapeutic effects of IPS e.max and VITA VM9 porcelain laminate veneers within 3 years． METHODS: Thirty IPS e.max veneers were made for 22 patients (30 affected teeth) and 29 VITA VM9 porcelain laminate veneers were made for 28 patients (29 affected teeth). Three years after restoration, color match, surface texture, marginal discoloration, and marginal integrity of two veneer systems were clinically examined following modified CDA/Ryge criteria. Clinical success rates were compared between two groups and patient satisfaction was assessed by visual analog scale. RESULTS AND CONCLUSION: Three years after restoration, there was one case of failure in the group of IPS e.max veneers, with the presence of gaps and dentin exposure, and one case of failure in the group of VITA VM9 porcelain laminate veneers, with the presence of insufficient margins and exposure of base materials. The success rate was 97% for both IPS e.max veneers and VITA VM9 porcelain laminate veneers, and there was no significant difference between the two kinds of veneers (P > 0.05). The patient satisfaction was scored as (86.38±7.83) points for IPS e.max veneers and (88.63±6.83) points for VITA VM9 porcelain laminate veneers, and no difference existed between the two kinds of veneers. To conclude, both IPS e.max and VITA VM9 porcelain laminate veneers are successful methods for veneer restorations． 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Therapeutic benefit of resin ball filling method for restoration of posterior approximal caries and its influence on periodontal health Liang Fei-zhao, Han Yue, Zhou Yan-ping, Liang Jian-mei, Li Gang 2018, 22 (22):  3480-3484.  doi: 10.3969/j.issn.2095-4344.0783 Abstract ( 597 )   PDF (629KB) ( 231 )   Save BACKGROUND: Resin has been widely used in the treatment of missing tooth tissue, but there are few reports about the application of resin in the repair of posterior approximal caries. OBJECTIVE: To investigate the therapeutic effect of resin ball filling on posterior approximal caries and its influence on periodontal health. METHODS: A patient population scheduled for the restorative treatment of posterior approximal caries consisted of 100 patients, 57 males and 43 females, 18-60 years of age. All the patients were randomized into a study group receiving resin ball filling and a control group given traditional filling. Periodontal probing depth, periodontal probing bleeding index, plaque index, proximal contact tightness and food impaction were detected at 6 months after restoration, and then the success rate of filling repair was statistically calculated. RESULTS AND CONCLUSION: (1) There was no significant difference in the success rate of filling between the study group and the control group (93.0% vs. 90.0%, P=0.447). (2) The clinical satisfaction rate of the study group was higher than that of the control group (94.0% vs. 46.0%, P < 0.001). (3) The rate of food impaction was lower in the study group than the control group (4.0% vs. 16.0%, P=0.024). (4) After 6 months of repair, the periodontal probing depth, periodontal probing bleeding index and plaque index of the two groups were significantly lowered (P < 0.05), but there was no significant difference between the two groups. In conclusion, compared with the traditional resin filling method, the resin ball filling for posterior approximal caries gets a better contact between the proximal surfaces, but no significant difference between the effects of the two filling methods on periodontal health. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Clinical effects of glass-fiber posts with different surface treatments on the restoration of tooth defects Shen Lin, Wang Ting-ting, Yu Shu-ling, Zhang Fang 2018, 22 (22):  3485-3490.  doi: 10.3969/j.issn.2095-4344.0750 Abstract ( 345 )   PDF (682KB) ( 105 )   Save BACKGROUND: Most current studies on the surface treatment of fiber posts are in vitro experiments aiming to simulate oral conditions, but it is impossible to simulate the actual conditions of oral environment. Therefore, clinical studies on the adhesion effects of fiber posts with various surface treatments are of great importance. OBJECTIVE: To evaluate the clinical effect of four different surface treatments of glass-fiber posts on the restoration of tooth defects. METHODS: A total of 178 patients (201 teeth) with dental defect who were treated by root canal treatment and scheduled for crown repair were randomly divided into four groups according to the surface treatment of fiber posts: no surface treatment in group A (n=51) was performed before bonding; group B (n=51) was restored with glass-fiber posts sandblasted before bonding; group C (n=53) was treated with hydrogen peroxide solution on the surface of the fiber post before bonding; and group D (n=46) was treated with silane coupling agent on the surface of the fiber post before bonding. Clinical follow-up to observe the restorative effect was done for 3 months to 2 years after restoration． RESULTS AND CONCLUSION: The success rate of dental restoration in groups B and C was significantly higher than that in groups A and D (P < 0.05), but there was no significant difference between groups B and C as well as between groups A and D (P > 0.05). The failure in dental restoration mainly resulted from root fracture, loosening and fracture of the post core. The incidence of root fracture, post core loosening and fracture, however, showed no difference among the four groups (P > 0.05). The survival rate of the patient’s restorative effect in groups B and C was better than that in group A (P < 0.05), and there was no significant difference in the survival rate of the patient's restorative effect between groups A and D as well as between groups B and C (P > 0.05). Overall findings indicate that the surface treatment of fiber posts with sandblasting or hydrogen peroxide solution significantly improves the clinical restoration of tooth defects and reduces the failure rate of glass-fiber posts. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Frictional force of different ligations with NiTi archwires of different sizes Ma Xiao-zhou, Li Hong-fa, Zhao Yan-hong, Wu Jie, Zhang Ming-can, Zhao Wei 2018, 22 (22):  3491-3497.  doi: 10.3969/j.issn.2095-4344.0916 Abstract ( 498 )   PDF (890KB) ( 227 )   Save BACKGROUND: Clinical evidence has proved that loose ligation can shorten the initial alignment time of the tooth compared with traditional ligation, but little is reported on the difference among loose ligation with NiTi archwires, self-ligation and traditional ligation. OBJECTIVE: To explore the frictional force of different orthodontic technologies by comparing the sliding frictional force of different ligations, brackets, and NiTi wires. METHODS: A plaster model with moderately crowded teeth was randomly and the bonding bracket was labeled using a cross mark. A corresponding dentition model was then copied by three-dimensional scanning and three-dimensional printing techniques. Different brackets, ceramic self-ligating brackets (Damon Clear, Habit), metal self-ligating brackets (Damon 3MX, AO), metal conventional bracket (3M) and ceramic conventional bracket (Habit) were bonded to the cross mark of the model. For each bracket, there were TiNi wires with four sizes, 0.012 (A) and 0.014 inch (B) hyperelastic NiTi, 0.014 inch thermally activated NiTi (C), and 0.014 inch Cu-NiTi (D). Tight and loose ligations were performed using two conventional brackets, and the sliding frictional force between the wire and the bracket was detected using a microcomputer servo dynamometer. RESULTS AND CONCLUSION: (1) For the loose ligation using the 3M conventional bracket, the sliding frictional force of different NiTi was ranked as A < C < B < D (P < 0.01); for the loose ligation using the Habit conventional bracket, the sliding frictional force of different NiTi was ranked as C < A < B < D (P < 0.01). (2) When using wire A or B, the sliding frictional force of 3M conventional bracket with loose ligation was higher than that of 3M self-ligating bracket and AO self-ligating bracket (P < 0.01) and was lower than that of 3M convention bracket with tight ligation (P < 0.01). When using wire C or D, the sliding frictional force of 3M conventional bracket with loose ligation was higher than that of AO self-ligating bracket (P < 0.01), but lower than that of 3M conventional bracket with tight ligation (P < 0.01). (3) When using any wire, the sliding frictional force of Habit conventional bracket with loose ligation was higher than that of Damon Clear self-ligating bracket and Habit self-ligating bracket (P < 0.01), and lower than that of Habit conventional bracket with tight ligation (P < 0.01). These experimental results reveal that loose ligation can reduce the frictional force of conventional brackets compared to traditional ligation, but it is still inferior to self-ligating brackets. Therefore, small-size and low-friction wires are recommended to further reduce the frictional force.  中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Sodium alginate/podophyllotoxin drug delivery system: preparation, release and anti-colon cancer effects Wang Jiang, Wang Qing-feng, Jiang Yi-xin, Chen Na, Chu Zheng 2018, 22 (22):  3498-3505.  doi: 10.3969/j.issn.2095-4344.0917 Abstract ( 375 )   PDF (846KB) ( 181 )   Save BACKGROUND: Podophyllotoxin has the function of inhibiting cancer cell proliferation, antiviral and pest resistance, but its use alone causes great adverse reactions and has low bioavailability. OBJECTIVE: To prepare sodium alginate/podophyllotoxin gel beads aiming to achieve the control release or targeted drug delivery that can improve effectiveness and reduce biotoxicity and adverse events. METHODS: External ion gel preparation of sodium alginate/podophyllotoxin gel beads was performed. Drug load efficiency of the gel beads with podophyllotoxin mass concentrations of 25, 50, and 75 g/L was detected, and swelling and release performance of the gel beads at different pH values (pH=2.1, 4.6, 7.4) was also measured. Colon cancer cells SW480 and intestinal epithelial cells NCM460 were cultured in the medium containing 5, 10, 20, 40 mg/L sodium alginate/podophyllotoxin gel beads, sodium alginate or podophyllotoxin alone. After 48 hours of culture, survival rate of NDM460 cells and inhibition rate of SW480 cells were detected. RESULTS AND CONCLUSION: The drug loading rate of the gel beads was 8.97%, 17.02% and 19.16% respectively, when the mass concentration of podophyllotoxin was 25, 50 and 75 g/L. When the mass concentration of podophyllotoxin was 25, 50 and 75 g/L, the gel beads were almost insoluble in the pH=2.1 and pH=4.6 environment. In the environment of pH=7.4, the swelling rate of gel beads increased with the increase of the mass concentration of podophyllotoxin. In the environment of pH=7.4, there was a slow release of podophyllotoxin, (69.5±9.1)%, from the gel beads in 24 hours. In the environment of pH=2.1 and 4.6, only (2.0±0.2)% and (2.1±0.6)% podophyllotoxin was released from the gel beads in 24 hours, respectively. With the increase of drug mass concentration, the survival rate of NCM460 cells in each group declined gradually. Sodium alginate had no cytotoxicity, but podophyllotoxin exhibited obvious cytotoxicity. Moreover, the gel beads could reduce the cytotoxicity of podophyllotoxin. With the increase of drug mass concentration, the inhibition rate of SW480 cells in each group increased gradually, and the inhibitory effect of the gel beads was stronger than that of sodium alginate and podophyllotoxin. These experimental findings indicate that the sodium alginate/podophyllotoxin gel bead is a promising pH sensitive slow-release colorectal cancer drug delivery system. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Topical usage of nerve growth factor-insulin gel on deep II scald wound increases microvessel density and proliferating cell nuclear antigen expression Xu Hai-tao, Wang Min, Xiang Xi-juan 2018, 22 (22):  3506-3512.  doi: 10.3969/j.issn.2095-4344.0847 Abstract ( 363 )   PDF (978KB) ( 180 )   Save BACKGROUND: Researches have shown that nerve growth factor can promote wound healing, but there are few reports on the topical application of nerve growth factor combined with medication on diabetic scald wound. OBJECTIVE: To explore the changes of microvessel density and proliferating cell nuclear antigen expression after topical application of nerve growth factor-insulin gel on deep II scald wound in diabetic rats. METHODS: Seventy-five Wistar rats were randomly divided into five groups. Deep II scald models were made on the back of rats in normal control group followed by topical application of Carbopol 980. Diabetic models and deep II scald models were both made in the remaining rats with an interval of 3 days. Then, the rats in the latter four groups were subjected to topical application of Carbopol 980 alone, or Carbopol 980 containing nerve growth factor, insulin and combination of nerve growth factor and insulin, respectively. The wound in each rat was redressed once a day, for 21 consecutive days. Wound healing rate, microvessel density and proliferating cell nuclear antigen expression in rats were detected at 3, 7, 11, 15, 21 days after scald. RESULTS AND CONCLUSION: Wound healing rate, microvessel density and proliferating cell nuclear antigen expression were higher in the combination group than the other four groups at different time after scald (P < 0.05). Results from hematoxylin-eosin staining showed that different structure damages, angiectasis and inflammatory cell infiltration were observed in different groups at 1 day after scald. A small amount of new capillaries were visible in each group, especially in the combination group at 3 days after scald. The number of capillary vessels and inflammatory cells increased gradually at 7-11 days after scald. Marked re-epithelialization and regular arrangement of collagen fibers were observed in the combination group at 15 days after scald. Meanwhile, compared with the normal control group and model group, the number of new vessels was increased in the nerve growth factor and insulin groups, but collagen fibers arranged disorderly. The wound in the combination group was covered with epithelial cells and collagen fibers arranged orderly at 21 days after scald, while there are different levels of epithelization in the other four groups. Higher level of epithelization was found in the nerve growth factor and insulin groups than the normal control and model groups. To conclude, topical application of nerve growth factor-insulin gel on deep II scald wound can promote wound healing by increasing microvessel density and proliferating cell nuclear antigen expression. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Mandibular defect repair by modified platelet-rich plasma combined with nanomaterials Xie Li-na, Zhao Bo, Chen Yuan, Jing Xiang-dong 2018, 22 (22):  3513-3519.  doi: 10.3969/j.issn.2095-4344.0918 Abstract ( 423 )   PDF (939KB) ( 184 )   Save BACKGROUND: With the help of bone tissue engineering, osteogenitor cells from the periosteum taken as “seed cells” are combined with nano-scaffold materials and growth factors to repair bone defects. OBJECTIVE: To explore the feasibility of reproducing platelet-rich plasma (PRP) using secondary centrifugation method through detecting platelet content, and to compare the osteogenic effects of different materials in different periods in order to explore new ways to repair bone defects with autologous periosteum and autologous active factors. METHODS: Eighteen New Zealand white rabbits were randomly divided into blank group, pure material group and active material group (n=6 per group). The PRP was prepared 1 day before operation, and the active materials were prepared with nano-hydroxyapatite/collagen/bone morphogenetic proteins (nHAC/BMPs). A rectangular penetrating bone defect animal model was made in the right mandibular body of each New Zealand white rabbit followed by implantation of pure materials, nHAC/BMPs/PRP and nothing in the pure material group, active material group and blank group, respectively. Experimental animals were executed at 4, 8 and 12 weeks after surgery. The mandible specimens were taken and compared among groups through radiography, scanning electron microscopy, and histological observations as well as new bone area calculation in the defect area. RESULTS AND CONCLUSION: The animal model of penetrating bone defect was successfully constructed and PRP was extracted effectively. The profile and imaging observations of the defect area showed better results in the pure material and active material groups than the blank group at each time. Under the scanning electron microscope, the boundary area of the blank group was mainly surrounded by fibrous tissues; there was a small amount of new bone in the boundary area of the material group; and the fibrous tissue of the active material group was dense and the flaky distribution of new bone was observed. The histological observation showed that the new bone formation in the bone defect area was superior in the material groups than that in the blank group, and there were more new bone and blood vessels in the active material group. Over time, the degraded material was surrounded and replaced by an active bone tissue. The area of new bone at 4 weeks after implantation was ranked as follows: blank group < pure material group < active material group, and there were significant differences between groups. The area of new bone in the blank group was significantly lower than that in the material groups at 8 and 12 weeks after implantation (P < 0.05), while there was no difference between two material groups (P > 0.05). To conclude, the nHAC/BMPs has good biocompatibility and osteoinduction activity in vivo, and it can be used as a scaffold material to guide the growth of regenerated bone tissue to the defect. PRP helps to induce and promote the osteogenesis of active materials and promote bone defect repair. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Preparation of N-hexane chitosan and its cytotoxicity and coagulation property Liu Meng-yuan, Jing Miao-lei, Guan Jing, Huang Shu-jie, Yang Jian, Li Zhi-hong 2018, 22 (22):  3520-3526.  doi: 10.3969/j.issn.2095-4344.0775 Abstract ( 367 )   PDF (1055KB) ( 125 )   Save BACKGROUND: Chitosan is a natural hemostatic material, but its hemostatic effect is limited and needs to be improved. Introducing alkyl groups into chitosan can modify its coagulation property. However, the coagulation mechanism of short alkyl groups that are grafted on chitosan powder is unclear until now. OBJECTIVE: To study the cytotoxicity and coagulation property of the prepared N-hexane chitosan. METHODS: N-hexane chitosan was prepared by reductive reaction and characterized by Fourier transform infrared spectroscopy and elemental analysis. Cytotoxicity of N-hexane chitosan was tested by MTT and fluorescence microscopy. Whole blood coagulation time, rheological properties and blood plasma coagulation time were evaluated for its coagulation effects. RESULTS AND CONCLUSION: (1) A series of N-hexane chitosans with substitution degree of 8.67%, 18.06%, and 32.88% were synthesized successfully. (2) MTT results showed that the toxicity of N-hexane chitosan was graded 0 and 1. Fluorescence staining results showed that L929 cells grew well on the materials and dead cells were scarcely visible, indicating the low toxicity of the materials.  (3) N-hexane chitosan could promote blood clotting, and its blood coagulation efficiency was increased with its substitution degree. No significant difference was found in activated partial thromboplastin time, prothrombin time and thrombin time of N-hexane chitosans with different substitution degrees. N-hexane chitosan could not promote activation of clotting factors. Its mechanism for accelerating coagulation needs in-depth investigations. N-hexane chitosan, compared with pure chitosan, shows better clotting effect, and this effect is enhanced with the increasing of the substitution degree. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Oxidized dextran/aminated carboxymethyl chitosan two-component hydrogel adhesive based on Schiff base reaction Li Dan-dan, Mo Xiu-mei 2018, 22 (22):  3527-3532.  doi: 10.3969/j.issn.2095-4344.0846 Abstract ( 602 )   PDF (792KB) ( 293 )   Save BACKGROUND: Dual-crosslinked hydrogel adhesives based on Schiff base reaction have certain network structure, good biocompatibility and high bond strength, which have good application prospects in tissue engineering and clinical medicine. OBJECTIVE: To prepare and characterize oxidized dextran/aminated carboxymethyl chitosan two-component hydrogel adhesives through a Schiff base reaction. METHODS: Dextran was oxidized with sodium periodate and carboxymethyl chitosan was aminated with ethylenediamine. Oxidized dextran/aminated carboxymethyl chitosan hydrogel adhesives were prepared by Schiff base reaction at room temperature. The structures of oxidized dextran and aminated carboxymethyl chitosan were characterized by infrared absorption spectroscopy. The iodine residue of oxidized dextran was measured by spectrophotometer, and the ethylenediamine residue of aminated carboxymethyl chitosan was determined by gas chromatography. The lap-shear tensile load strength, T-peel tensile load strength and tensile strength of oxidized dextran/carboxymethyl chitosan and oxidized dextran/aminated carboxymethyl chitosan hydrogel adhesives were tested using a universal testing machine according to industry standards. RESULTS AND CONCLUSION: (1) IR spectra showed that the peak intensity of oxidized dextran decreased compared with that of dextran, with a new absorption peak appearing at 1 733 cm-1, corresponding to the hemiacetal structure. The carboxymethyl chitosan itself had broad peak at 3 358 cm-1, corresponding to the stretching vibration of the amine and hydroxyl groups, and the absorption peak at 3 358 cm-1 of aminated carboxymethyl chitosan increased significantly. (2) The oxidation degree of dextran was 73.42%, and the iodine residue was  138.58 μg/g. The amino group content of aminated carboxymethyl chitosan was 0.636 9 mmol/L and no ethylenediamine resided. (3) The lap-shear tensile load strength, T-peel tensile load strength and tensile strength of oxidized dextran/aminated carboxymethyl chitosan hydrogel adhesives increased by 47.48%, 17.54% and 76.42%, respectively, with a significant increase compared with oxidized dextran/ carboxymethyl chitosan hydrogel adhesives. These results show that the oxidized dextran/aminated carboxymethyl chitosan hydrogel adhesive has higher lap-shear tensile load strength, T-peel tensile load strength and tensile strength. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Polypropylene versus polyester patches for inguinal hernia repair: pain relief and changes in plasma superoxide dismutase and malondialdehyde levels Zheng Bing, Wang Wei, Ren Rui, Zhu Tao, Lu Ling-jun, Lu Chang-you 2018, 22 (22):  3533-3538.  doi: 10.3969/j.issn.2095-4344.0774 Abstract ( 427 )   PDF (623KB) ( 148 )   Save BACKGROUND: Polyester and polypropylene patches are commonly used patch materials for inguinal hernia repair. Both of them have their own characteristics. OBJECTIVE: To observe and compare the effects of different patches on plasma superoxide dismutase and malondialdehyde levels as well as pain relief in male inguinal hernia patients. METHODS: One hundred and twenty male patients with inguinal hernia were divided into three groups (n=40 per group): a control group treated with traditional hernia repair surgery, a polypropylene patch group and a polyester patch group treated with tension-free hernia repair using polypropylene or polyester patches. Operation time, hospitalization time, patch fixation time, time for urinary catheter removal, and bed time were recorded. Visual Analogue Scale was used for pain assessment before and 12, 24, 48, 72 hours after repair. Plasma levels of superoxide dismutase and malondialdehyde were detected before and 1, 2, 7 days after repair. RESULTS AND CONCLUSION: Compared with the control group, the operation time, hospitalization time and bed time were shorter in the polyester and polypropylene patch groups (P < 0.05), but there was no significant difference in the time for removal of urinary catheters among the three groups. Moreover, there was also no significant difference in the patch fixation time between the two patch groups. The Visual Analog Scale scores in the three groups were all significantly decreased at 12, 24, 48, 72 hours after repair with the baseline data (P < 0.05), while there was no significant difference among the three groups. At postoperative 1, 2, 7 days, the plasma level of superoxide dismutase was significantly lower in the polyester patch group than the polypropylene patch group (P < 0.05), while the level of malondialdehyde was ranked as follows: polyester patch group > polypropylene patch group > control group (P < 0.05). These findings indicate that both traditional hernia repair and tension-free hernia repair can significantly relieve the pain of male inguinal hernia patients. Patch implantation can change the plasma levels of superoxide dismutase and malondialdehyde in patients with inguinal hernia; in contrast, the polypropylene patch only results in a little effect on the levels. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Porcine decellular endplate cartilage matrix: biocompatibility assessment and establishment of a cytotoxicity evaluation system Wang Xiao, Xu Hong-guang, Xiao Liang, Liu Chen, Jin Zhong-xing, Shen Yang 2018, 22 (22):  3539-3544.  doi: 10.3969/j.issn.2095-4344.0920 Abstract ( 451 )   PDF (895KB) ( 136 )   Save BACKGROUND: Compared to other high-molecular compounds used for scaffold materials, the decellular endplate cartilage matrix (DEPM) can simulate the extracellular environment closer to the original physiological state, and the elastic modulus of the intervertebral disc scaffold made of DEPM therefore is closer to that of the cartilage tissue. OBJECTIVE: To prepare DEPM and explore its biocompatibility at cellular level and in vivo.   METHODS: Porcine endplate cartilage samples were crushed and digested with Trypsin combined with ribozyme and TritonX-100 to obtain DEPM. (1) Cytotoxicity test: After dissolved in acetic acid, the DEPM was prepared into the acellular matrix membrane. Cartilage stem cells from the lumbar endplate of Sprague-Dawley rats were seeded onto the acellular matrix membrane, and cell proliferation was detected using cell counting kit-8 after 1-5 days of culture. Then cytotoxicity of the cells was graded. (2) Toxicity test in vivo: Acetic acid containing DEPM (experimental) or not (control) was subcutaneously injected into the back of Sprague-Dawley rats to form a bump. Rat body temperature and bump’s size were observed within 36 hours after injection. RESULTS AND CONCLUSION: (1) Cytotoxicity test: Under the inverted microscope, cartilage stem cells from the lumbar endplate were adherent within 2 days after implantation, and grew in a fusiform shape. The relative cell growth rate was over 80% within 5 days after implantation, and the cell toxicity grade was level 0 to 1. (2) Toxicity test in vivo: A bump was formed on the rat back in the two groups immediately after injection, and completely disappeared within 36 hours after injection. Moreover, the absorption rate in the control group was faster than that in the experimental group. No red and swelling bump occurred in the two groups. the body temperature of the rats in the two groups did not exceed 37.5 ℃ within 36 hours after injection. To conclude, the DEPM has good biocompatibility, which is in line with the selection criteria of biological scaffolds. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Vascular endothelial growth factor-modified bladder acellular collagen matrix for repair of urethral defects Li Gui-li, Zhao Qi-lin 2018, 22 (22):  3545-3549.  doi: 10.3969/j.issn.2095-4344.0921 Abstract ( 384 )   PDF (638KB) ( 108 )   Save BACKGROUND: Modification by vascular endothelial growth factors (VEGF) contributes to the repair of urethral defects using bladder acellular collagen matrix scaffolds. However, there is a dispute in different experimental results. OBJECTIVE: To investigate the effect of VEGF-modified bladder acellular collagen matrix in the repair of rabbit urethral defects. METHODS: Forty-eight rabbits were randomized into four groups (n=12 per group): no intervention was done in normal group; an animal model of urethral defect was made in the model, control and experimental groups, followed by implantation of nothing, bladder acellular collagen matrix and VEGF-modified bladder acellular collagen matrix, respectively. Rabbit urinary flow rate and maximal urethral pressure were measured. Hematoxylin-eosin staining was performed on the urethral defects to observe the urethral tissue repair and to detect the number of microvessels at 1 month after modeling. RESULTS AND CONCLUSION: (1) At 1 month after modeling, the urinary flow rate and maximal urethral pressure in the experimental group had no statistical significance compared with the normal group (P > 0.05), but were significantly higher than those in the model and control groups (P < 0.05). The urinary flow rate and maximal urethral pressure in the model group were significantly lower than those in the normal and control groups (P < 0.05). (2) At 1 month after modeling, the urethral tissue in the normal group was clear with the epithelial cells being arranged regularly. The urethral tissues in the model group were relatively ambiguous shown by hematoxylin-eosin staining, the epithelial cells were arranged disorderly, and a large amount of inflammatory cells in the repair tissue were infiltrative. The epithelium in the experimental group was well repaired, incompletely degraded collagen matrix and new blood vessels were detected, and no inflammatory cell infiltration was observed. The mucosal epithelium in the control group was generally repaired, but no obvious neovascularization was visible, with a few inflammatory cell infiltrations. (1) At 1 month after modeling, the number of microvessels in the experimental group was significantly higher than that in the other three groups (P < 0.05), and the number of microvessels in the control group was also higher than that in the model group (P < 0.05). Overall, the use of VEGF-modified bladder acellular collagen matrix in the repair of rabbit urethral defects can promote local neovascularization and improve the environment for promoting urethral regeneration. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Preparation and inflammation suppression of pH sensitive chitosan/dexamethasone sodium phosphate nano-drug delivery system Chen Na, Xie Tie-min, Zhang Yi-fan, Wang Jiang, Wang Qing-feng 2018, 22 (22):  3550-3556.  doi: 10.3969/j.issn.2095-4344.0919 Abstract ( 473 )   PDF (902KB) ( 224 )   Save BACKGROUND: The clinical utilization of dexamethasone sodium phosphate in the treatment of asthma is limited due to its toxicity and short metabolic time, which means, a slow-release preparation of dexamethasone sodium phosphate is a good solution. OBJECTIVE: To prepare a pH sensitive chitosan/dexamethasone sodium phosphate nanoparticle, and to investigate its drug loading, microstructure, particle size distribution, in vitro release characteristics, and anti-inflammatory effect. METHODS: Chitosan as raw material was used to prepare pH sensitive chitosan/dexamethasone sodium phosphate nanoparticles by ionic gelation method. Drug-polymer interactions, morphology, particle size distribution and in vitro release characteristics of the nanoparticles were then detected. Thirty-two Sprague-Dawley rats were randomly divided into four groups: the normal group was subcutaneously injected 1 mL of normal saline at days 0 and 7, and inhaled 1 mL of atomized saline, 30 minutes per day, from day 14 to day 21. The asthma group was subcutaneously injected 1 mL of sensitization solution at days 0 and 7, and inhaled 1 mL of atomized saline solution containing 1% ovalbumin, 30 minutes per day, from day 14 to day 21. The control group was intraperitoneally injected dexamethasone sodium phosphate (0.25 mg/kg) at 30 minutes before induction of asthma, and the other procedures were the same as those used in the asthma group. The experimental group was intraperitoneally injected chitosan/dexamethasone sodium phosphate nanoparticles (0.25 mg/kg dexamethasone sodium phosphate) at 30 minutes before induction of asthma, and the other procedures were the same as those used in the asthma group. Lung tissue samples from each rat were taken at day 14 for histological observation using hematoxylin-eosin staining. RESULTS AND CONCLUSION: (1) With the increase of dexamethasone sodium phosphate concentration, the drug-loading rate of chitosan/dexamethasone sodium phosphate nanoparticles increased gradually. (2) The chitosan/dexamethasone sodium phosphate nanoparticles obtained were white oval, 95% of which had a diameter of 40-70 nm, with the average diameter being 53.2 nm. (3) In the simulated intestine solution (pH=7.4), sodium dexamethasone phosphate was gradually released from the nanoparticles and completely released within 120 minutes. In the simulated gastric juice (pH=2.1 and pH=4.6), no sodium dexamethasone phosphate was released within 120 minutes. (4) Hematoxylin-eosin staining results showed that the bronchial smooth muscle in the asthma group was hypertrophic accompanied by mucosal hyperemia and edema and infiltration of plenty inflammatory cells. Bronchial inflammation was relieved in the control group, and considerably alleviated in the experimental group, where only a small number of inflammatory cells were infiltrated around the bronchial wall. We make a conclusion from these findings that pH-sensitive chitosan/dexamethasone sodium phosphate nanoparticles exhibit a slow-release potential, which can be used to inhibit the production of inflammatory cells in asthmatic rats given broncho-alveolar lavage 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Preparation and biocompatibility of an electroactive polyaniline/poly(lactic-acid) scaffold Wang Ling-ling, Cui Zhi-ming, Xu Guan-hua, Li Wei-dong, Bao Guo-feng, Sun Yu-yu, Chen Jia-jia, Zhang Jin-long 2018, 22 (22):  3557-3562.  doi: 10.3969/j.issn.2095-4344.0755 Abstract ( 372 )   PDF (738KB) ( 140 )   Save BACKGROUND: Previous studies have confirmed that polyaniline/poly(lactic-acid) scaffold could promote the growth of neural stem cell processes in the condition of electrical stimulation. OBJECTIVE: To prepare an electroactive polyaniline/poly(lactic-acid) scaffold and to investigate its biocompatibility with rat olfactory ensheathing cells. METHODS: Olfactory ensheathing cells of Sprague-Dawley neonatal rats were inoculated onto the polyaniline/poly(lactic acid) film (experimental group) and poly lysine coating slides (control group). Cell proliferation and cell adhesion rate were detected, and the cells were observed with immunofluorescence histochemistry. RESULTS AND CONCLUSION: (1) Smooth and even polyaniline/poly(lactic acid) film was visible under electron microscopy, with a grid structure formed by fine fibers, and its conductivity was 1.5×10-5 S/cm. (2) At 1, 3, 5, 7 days after co-culture, the cell relative growth rates were all above 90%, and the cytotoxicity was graded I. (3) At 7 days after co-culture, the cell adhesion rate in the experimental group was significantly higher than that in the control group (P < 0.05). (4) At 7 days after co-culture, immunofluorescence results showed that there was no obvious difference between the two groups in the number or area of S-100 positive cells (P > 0.05), while the cell perimeter in the experimental group was significantly higher than that in the control group (P < 0.05). To conclude, the prepared polyaniline/poly(lactic acid) film has good biocompatibility with olfactory ensheathing cells.   中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Hemodynamic analysis of coronary stents in curved vessels Tang Dan, Yuan Quan, Wang Zhi-chao, Zhu Hong-wei 2018, 22 (22):  3563-3568.  doi: 10.3969/j.issn.2095-4344.0886 Abstract ( 412 )   PDF (883KB) ( 251 )   Save BACKGROUND: As shown in the hemodynamic simulation test for stent implantation, the simulated blood vessels are generally designed to be straight but not curved. In order to make the simulation results reliable, the simulation model should be very close to the actual situation. OBJECTIVE: To study the restenosis of the curved coronary artery, and to establish a model of curved blood vessels close to the actual situation of the human body so as to explain why the restenosis rate is relatively high for the curved coronary artery after stenting in clinic. METHODS: The three-dimensional coronary stent model was established by Creo5 modeling software. Blood flow models (curved vessel-stent flow field) of curved coronary arteries (30°, 45°, 60°) and corresponding stents were established by means of Boolean calculation through the use of Ansys18.0 finite element simulation software. At the same time, a blood flow model (straight vessel-stent flow field) of the straight coronary artery under the same stent was established for comparison. After the study on fluid simulation, the proportion of wall shear stress (WSS) < 0.5 Pa and the flow resistance are compared in the two cases. RESULTS AND CONCLUSION: (1) The WSS of the area with on stent in the two models was basically the same between 0.5-1.0 Pa, and the low WSS values were distributed in the lateral area of the stent strut whether in the straight vessel-stent flow field model or the curved vessel-stent flow field model. What’s more, a large low WSS area appeared at the end of the stent in the curved vessel-stent flow field model. (2) The area of WSS < 0.5 Pa accounted for 16.14% of the total area in the straight-stent flow field model, while this proportion was 25.21%, 28.65%, 26.63% in the curved vessel-stents (30°, 45°, 60°), respectively, indicating the rate of restenosis in the curved vessel stents were relatively high. (3) The distribution of WSS in all curved vessel-stent models were basically the same regardless of the curvature. (4) The flow resistance of the curved vessel-stent models (30°, 45°, 60°) [1.50, 1.82, 2.17 N•s2/(kg•m)] was higher than that of the straight vessel stent model [1.03 N•s2/(kg•m)]. To conclude, the rate of restenosis in the curved vessel stent is relatively higher than that in the straight vessel stent model.    中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Uroflowmeter calibration device: standard water flow and its stability Wang Li-xin, Ji Jun, Gao Jia-shuo, Xiao Hong 2018, 22 (22):  3569-3574.  doi: 10.3969/j.issn.2095-4344.0892 Abstract ( 351 )   PDF (782KB) ( 159 )   Save BACKGROUND: As the gear pump’s leakage and pulsation are not taken into account to the design of the uroflowmeter calibration device composed of digital signal processor (DSP) and gear pump, a wrong result will be produced if we just calibrate the urinary flow meter with the theory flow data that work out by the recorded data of the gear pump’s rotate speed. OBJECTIVE: Based on the designed uroflowmeter calibration device, using DSP timer to control the operation time of the gear pump to obtain a standard water flow with fixed rate and quantity, to measure the quantities of each standard water flow and to analyze the measurement results in order to test if the standard water flows produced by the uroflowmeter calibration device are suitable to calibrate urine flow rate in clinic. METHODS: The quantity of each standard water flow was measured by B2000S scales in different time by different experimenters. SPSS 20.0 software was then used to draw the distribution histogram of each standard water flow measurement results. We also analyzed the factors affecting the uncertainty of the measurement results, and calculated the uncertainty of the results by systematic analysis. RESULTS AND CONCLUSION: (1) The quantities of each standard water flow measured by different experimenters in different time were consistent with normal distribution. The maximum stand deviation was 0.549 mL at the flow rate of 15 mL/s, and the minimum stand deviation was 0.147 mL at the flow rate of 10 mL/s. This indicates that the standard water flow produced by the uroflowmeter calibration device has a very high stability, both in flow rate and in flow volume. Therefore, the mean value of the multiple measurement results can be used as the best estimated value of the standard water flow. (2) The uncertainty of the measurement results were calculated by systematic analysis. The uncertainty was 0.75 mL in maximum at the rate of 50 mL/s, and 0.29 mL in minimum at the rate of 10 mL/s, which meets the requirement that the maximum rate between the uncertainties of a standard device and a calibrated device is less than 1:3. Therefore, the uroflowmeter calibration device can be used to calibrate urine flow rate in clinical practice. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Hemostatic dressings for prehospital trauma care: strengths, problems and prospects Sun Guo-fei, Liu Jian-heng, Zhang Li-cheng, Zhang Li-hai, Tang Pei-fu 2018, 22 (22):  3575-3582.  doi: 10.3969/j.issn.2095-4344.0735 Abstract ( 559 )   PDF (852KB) ( 275 )   Save BACKGROUND: When traumatic bleeding happens in the battlefield and remote areas, hemostatic dressings as an assisted hemostasis can provide a good hemostatic effect when the traditional method is failure to stop bleeding. OBJECTIVE: To analyze the characteristics, components, side effects and hemostatic mechanism of hemostatic dressings, in order to explore a safe and effective hemostatic dressing for prehospital or emergent trauma care. METHODS: PubMed, Embase and CNKI were retrieved using the MeSH words of “hemorrhage, wounds, injuries, hemostasis” in English and the keywords of “hemorrhage, blood loss, injuries, trauma, war, battle, hemostasis” in English and “hemostasis, bleeding, hemostatic agent, hemostatic dressing, wound, prehospital” in Chinese. RESULTS AND CONCLUSION: Hemostatic dressings are classified into concentrated coagulation factors, tissue adhesives and supplementary procoagulant factors according to the mechanism of action. These dressings have been greatly improved in the hemostatic effect and avoiding side effects, several of which have won FDA approval and applied on the battlefield. Up to now, there is still no ideal hemostatic dressing. Further investigations are required to determine the hemostatic effect and potential adverse reactions of the existing hemostatic dressings. More efforts will be made to discover new and safe hemostatic dressings. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Physical and chemical properties of 3D extrusive bioprinting cell-encapsulated hydrogel Gu Ya-wei, Li Mu, Fan Zi-wen, Wang Long, Li Ze-yao, Chen Chang 2018, 22 (22):  3583-3588.  doi: 10.3969/j.issn.2095-4344.0746 Abstract ( 440 )   PDF (697KB) ( 517 )   Save BACKGROUND: 3D bioprinting technology can be used to print non-cell and cell-laden materials, which provides a new pathway to solve the lack of transplanted organs or bio-patches. OBJECTIVE: To conclude the printing mechanisms, kinds, biological and mechanical characteristics of hydrogels based on the development and advance in 3D extrusive bioprinting hydrogel. METHODS: A computer-based search of PubMed database was performed to retrieve relevant articles published between 2006 and 2016, with the keywords of “3D bioprinting/three-dimensional bioprinting; extrusion/extrusive; cell-laden/cells/cellular; hydrogel”. RESULTS AND CONCLUSION: 3D bioprinting is characterized as simple principle, controlled process, and less energy production, which can manufacture personalized organs or scaffolds by rapid prototyping technology, and precisely construct tissues with controllably distributed cells to mimics the physiological circumstance. However, 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程   the following aspects are still at an initial stage, including the biological behaviors of cells in hydrogel, the interactions between cells and hydrogels and the elevation of micro-nano precision of printing. With solutions to these problems, 3D bioprinting may become another novel construction method in the tissue engineering. Figures and Tables | References | Related Articles | Metrics

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Development of surface treatments for medical magnesium alloys Zhang Yong-qiang, Zhao Jian-ning, Bao Ni-rong 2018, 22 (22):  3589-3594.  doi: 10.3969/j.issn.2095-4344.0731 Abstract ( 317 )   PDF (703KB) ( 124 )   Save BACKGROUND: Magnesium alloys with good biological properties and mechanical properties have already been used as biodegradable metals for a long time, but their clinical applications are still limited due to their excessive degradation rates. At present, there are many methods to control the corrosion rate of magnesium alloys, including alloying, surface treatments, improving the purity, use of composite materials. Among them, surface treatments have become a hot spot. OBJECTIVE: To summarize and discuss the surface treatments for medical magnesium alloys and compare their biosafety and application status. METHODS: The first author searched literature from CNKI (2007/2017) and PubMed (2007/2017). The key words were “magnesium alloy, corrosion rate, surface treatment, biosecurity” in Chinese and English, respectively. We reviewed the included articles in the aspects of surface treatments, variation of degradation rate and biosafety, and systematically introduced merits and demerits of surface treatments for medical magnesium alloys. RESULTS AND CONCLUSION: Initially, 464 papers were retrieved, and only 40 eligible ones were included in result analysis. Surface treatments for medical magnesium alloys can be divided into two main categories: coating and structural modification, which can effectively decrease the degradation rate, and change the biosafety and mechanical properties of the magnesium alloys. Future studies on the surface treatments for magnesium alloys will focus on the combination use of surface modification and surface coating technology to create a new biodegradable metal implant in line with the clinical needs. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Membrane biomaterials in tissue engineering: an outlook on guided membrane regeneration theory Li Li1, Zhang Heng2, Tang Li-bo1 2018, 22 (22):  3595-3601.  doi: 10.3969/j.issn.2095-4344.0777 Abstract ( 373 )   PDF (803KB) ( 227 )   Save BACKGROUND: Membrane biomaterials are a kind of basic materials closely related to tissue engineering and regenerative medicine, which have been widely used in tissue construction and organ regeneration. OBJECTIVE: To review a variety of film forming materials and their application in tissue regeneration. METHODS: PubMed and Chinese Journal Full-Text Database were searched by computer for articles concerning membrane biomaterials published from January 2002 to March 2017. The key words were “membrane biomaterial, scaffold, tissue engineering, regeneration medicine" in English and Chinese, respectively. Initially 133 articles were retrieved, and finally 45 articles were included in result analysis. RESULTS AND CONCLUSION: Membrane biomaterials from different origins can be divided into natural acellular matrix membrane, organic polymer membrane and synthetic macromolecular membrane. Natural organic polymer membranes, including proteins and polysaccharides, have been prepared by natural organic polymer materials using chemical or physical treatments. Synthetic organic macromolecules are various, mainly including polylactic acid, polyglycolic acid and their copolymers, polyvinyl alcohol, polycaprolactone, polyhydroxybutyrate. Until now, a membrane regeneration theory gradually forms in the basic field based on the use of membrane biomaterials in tissue engineering, which has been widely used in the bone induction. Extensive research is warranted to improve the guided membrane regeneration theory and popularize its application in tissue regeneration. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics

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Digital technology in prosthodontics: impression, shade selection, material design and processing Yu Jia-li, Nie Er-min, Jiang Rui, Zhang Chun-yuan, Huang Zhe-xun, Zhang Yu-hang, Lu Dun-lang 2018, 22 (22):  3602-3608.  doi: 10.3969/j.issn.2095-4344.0850 Abstract ( 448 )   PDF (756KB) ( 181 )   Save BACKGROUND: Digital technology has been widely used in the oral field. With the continuous development of material science and computer application science, the popularity of this technology has soared owing to its facilitation, precision, and reduction in healthcare costs. OBJECTIVE: To review the present situation and prospect of digital technology in prosthodontics. METHODS: A computer-based online research of PubMed and CNKI databases was performed for relevant  articles published from January 2012 to November 2017 using the keywords of “digital technology, CAD/CAM technology, digital impression, digital dental shade selection, 3D printing technology” in English and in Chinese, respectively. After removal of repetitive articles, finally 68 eligible articles were included in result analysis. RESULTS AND CONCLUSION: Digital technology has been widely used in the oral field, including single crown, inlays, veneer, fixed bridge, removable partial dentures and complex complete denture. Compared to traditional dental restoration methods, this technology has better timeliness, aesthetics, and economy in digital impression, digital dental shade selection, digital design and production. With the continuous development of science and technology, digital technology has great potential and future in dentistry. 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程 Figures and Tables | References | Related Articles | Metrics