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15 October 2013, Volume 17 Issue 42 Previous Issue    Next Issue

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The microstructure of antigen-extracted heterologous bone Cui Jie, Li Zheng, He Hui-yu, Hu Yang 2013, 17 (42):  7341-7348.  doi: 10.3969/j.issn.2095-4344.2013.42.001 Abstract ( 278 )   PDF (3072KB) ( 520 )   Save BACKGROUND: Different methods to remove immunogenicity have different effects on the spatial microstructure of antigen-extracted heterologous bone. OBJECTIVE: To compare the microstructure of the antigen-extracted heterologous bone via different methods to provide experimental data for tissue engineering industrialization. METHODS: Fresh cancellous bones extracted from adult sheep vertebrae were prepared into cylinders. Their long axis direction was the same with orientation of the trabeculae. After vibration washing and different-frequency ultrasound rinsing, the cylinder samples were randomly divided into three groups: in physical calcined group, the samples were defatted, decellularized and deproteinized sequentially using methanol/chloroform and hydrogen peroxide, then bathed in sodium pyrophosphate and directly calcined at     1 000 ℃ for 3 hours; in chemical group, the samples were defatted, decellularized and deproteinized sequentially using methanol/chloroform and hydrogen peroxide; in control group, the samples were dried naturally at room temperature. Microstructure of the samples in each group was analyzed and compared through determination of porosity, scanning electron microscopy observation, X-ray diffraction analysis, X-ray atomic spectroscopy elemental analysis microscopic spatial structure. RESULTS AND CONCLUSION: The physical calcined and chemical groups maintained natural network pore  system to different extents. The size of the large pore was 50-600 μm and that of the small one was about 2 μm. The porosity was 55% to 70%. Hydroxyapatite was the main component of the physical calcined group which was determined by X-ray diffraction, and a small amount of the β-Tricalcium phosphate was also determined. In the chemical group, the main component was only hydroxyapatite. The three-dimensional spatial structures of the deproteinized cancellous bones were not damaged greatly, and they had a natural pore network system. Antigen component of xenogeneic cancellous bone can be more thoroughly removed by physical calcination step. The scaffold material made by antigen-extracted heterologous bone may satisfy the demands for bone tissue-engineering scaffolds. Figures and Tables | References | Related Articles | Metrics

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In vitro constructing artificial biomimetic periosteum Sun Rui, Chen Xiao-fei, Zhao Lin, Zhao Jian-hong, Yu Jia-jia, Ren Guang-tie, Tuo Zhen-he 2013, 17 (42):  7349-7355.  doi: 10.3969/j.issn.2095-4344.2013.42.002 Abstract ( 423 )   PDF (2074KB) ( 569 )   Save BACKGROUND: The small intestinal submucosa has good biocompatibility and biodegradability, and also contains a variety of growth factors that can significantly promote cell adhesion, proliferation and differentiation. Currently, the small intestinal submucosa has been widely used in bone and cartilage, blood vessels, skin, bladder, smooth muscle and pancreatic tissue repair, showing good performance as a tissue-engineered cell scaffold. OBJECTIVE: To investigate the in vitro feasibility of tissue engineered periosteum constructed by porcine small intestinal submucosa and osteoblasts differentiated from bone marrow mesenchymal stem cells. METHODS: Bone marrow mesenchymal stem cells were harvested from 2-week-old healthy New Zealand rabbits by using adherent method, and then cells were cultured, induced, differentiated and identified in vitro. Following induced differentiation and identification, the bone marrow mesenchymal stem cells were compounded with porcine small intestinal submucosa to fabricate tissue engineered periosteum. The adhesion, growth, and proliferation of cells on the materials were observed. RESULTS AND CONCLUSION: At 5 days after inoculation, the cells receiving osteogenic induction could quickly adhere and proliferate on the surface of porcine small intestinal submucosa and be interconnected; at 10 days, the desmosomes formed among the cells, cell processes from osteoblasts were visible and attached to the small intestine submucosa; at 15 days, cell proliferation and secretion of matrix appeared, and multi-layer  membrane-like structure formed on the surface of the small intestine submucosa. These findings indicate that after osteogenic induction, the bone marrow mesenchymal stem cells can be combined with porcine small intestinal submucosa to construct a tissue engineered periosteum, which is hoped to be an ideal scaffold for tissue engineering. Figures and Tables | References | Related Articles | Metrics

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Calcitonin gene-related peptide induces the osteogenic differentiation of adipose derived stem cells combined with calcium alginate gel Huang Chang-zhi, Yang Xiao-ning, Liu Da-cheng, Sun Yi-gong, Dai Xing-ming 2013, 17 (42):  7356-7362.  doi: 10.3969/j.issn.2095-4344.2013.42.003 Abstract ( 366 )   PDF (2359KB) ( 391 )   Save BACKGROUND: Calcitonin gene-related peptide has been confirmed to induce osteogenic differentiation, but whether it can induce the osteogenic differentiation of adipose-derived stem cells under three-dimensional culture to construct tissue-engineered bone is rarely reported. OBJECTIVE: To investigate the feasibility of exogenous calcitonin gene-related peptide to induce osteogenic differentiation of adipose-derived stem cells combined with calcium alginate gel in three-dimensional condition. METHODS: Adipose-derived stem cells were gained by collagenase I digestion of the subcutaneous adipose tissue of both inguinal regions of New Zealand rabbits. Passage 3 cells were mixed with sodium alginate to prepare calcium alginate gel, and then the cells were assigned into two groups and cultured in 24-well plates. Adipose-derived stem cells in the control group were cultured in Dulbecco’s modified Eagle’s medium/Ham’s nutrient mixture F-12 supplemented with 10-2 mol/L β-glycerophosphate sodium, 10-7 mol/L dexamethasone,   50 mg/L ascorbic acid, 10% fetal bovine serum. While, adipose-derived stem cells in the experimental group were  incubated with the same medium as above, but 1.5 µg/L calcitonin gene-related peptide was added. The cells proliferation and the mRNA expressions of collagen I and osteocalcin were detected by  3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and reverse transcription-PCR respectively, and alkaline phosphatase and calcium concentration were detected at different induction time. RESULTS AND CONCLUSION: The cell proliferation curves were S shaped. The absorbance values of the experimental group were higher than those of the control group at1, 3, 5, 7, 14, 21 days after osteogenic induction (P < 0.05). Alkaline phosphatase and alizarin red staining of adipose-derived stem cells was all positive, but golden round nodes became more and bigger in the experimental group compared with the control group after 2 weeks. At 7 and 14 days, collagen I and osteocalcin mRNA expressions were higher in the experimental group than in the control group. Alkaline phosphatase activity and calcium concentration of the experimental group were higher than those of the control group at 1, 2, 3, 4 weeks after osteogenic induction (P < 0.05). Results showed that the calcitonin gene-related peptide can induce the osteogenic differentiation of adipose-derived stem cells combined with calcium alginate gel. Figures and Tables | References | Related Articles | Metrics

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Corrosion behavior of Ti-Cu coating on the surface of bone magnesium alloy Zang Zhi-hai, Yin Dong-song, Xu Xiao-jing, Yin Qing-wei, Wang Li-gang, Liu Wen-jun 2013, 17 (42):  7363-7368.  doi: 10.3969/j.issn.2095-4344.2013.42.004 Abstract ( 288 )   PDF (1994KB) ( 428 )   Save BACKGROUND: Magnesium alloy as a fracture fixation material has mechanical properties similar to the bone, good biocompatibility and biodegradability, but its rapid degradation rate in body fluids becomes a clinical bottleneck. Therefore, the use of surface treatments to improve its corrosion resistance is important. OBJECTIVE: To use magnetron sputtering technology and alkali heat treatment technology in the preparation of coating characterized as both corrosion resistance and biological activity. METHODS: First, we prepared Mg-Zn-Mn alloy using the smelting technology, and prepared a dense coating on the alloy surface by the magnetron sputtering technique. Then, we processed the coating surface using an alkaline solution, and studied the corrosion behavior of the coating by use of simulated body fluid experiments. We speculated the biological activity of the coating by measuring the content of calcium and phosphorus from the surface products. RESULTS AND CONCLUSION: We prepared the coating, which had both corrosion resistance and biological activity, on the surface of magnesium alloy by use of magnetron sputtering and alkali heat treatment technology. After soaking in the simulated body fluid for 24 hours and 168 hours, the deposition of the coating surface contained Ca, P products. Ca/P ratios were 1.54 and 2.11, respectively, closed to the bone-phosphate Ca/P ratio. The coating surface formed 5-10 μm pitting after 24 hours of immersion, and the pitting grew up with the immersion time. The pitting was enlarged to 100-800 μm after 168 hours. Figures and Tables | References | Related Articles | Metrics

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Attachment and proliferation of bone marrow mesenchymal stem cells cultured on porous tantalum rod Zhao Zhen-hua, Zhao De-wei, Fu Wei-min, Wang Ben-jie, Wei Xiao-wei, Wang Wei, Liu Bao-yi 2013, 17 (42):  7369-7374.  doi: 10.3969/j.issn.2095-4344.2013.42.005 Abstract ( 227 )   PDF (1992KB) ( 472 )   Save BACKGROUND: Porous tantalum rods, possessing high porosity and highly similar elastic modulus to the trabecular bone, not only can provide effective mechanical support for the femoral head, but also can enhance revascularization in the areas of necrosis, reduce stress shielding, and provide guarantee for bone ingrowth in necrotic area. OBJECTIVE: To investigate the attachment and proliferation of bone marrow mesenchymal stem cells on the surface of porous tantalum rod. METHODS: The purified bone marrow mesenchymal stem cells which were separated from canines were seeded on the surface of porous tantalum rod by the cell density of 1.5×109/L. Cell attachment and proliferation was observed under phase microscope and scanning electron microscope at 5, 10 and 15 days under co-cultured condition. RESULTS AND CONCLUSION: (1) Inverted microscope: Within 1-5 days after co-culture, the cells began to proliferate, and less cells were found near the tantalum rod, but more cells far from the rod. At 6-10 days after co-culture, the cells increased significantly and gradually migrated to the rod, and even some cells attached to the edges of the rod. After 14 days, the cells were interconnected to form a film, packing the surrounding and dents of the tantalum rod. Cells were visible to agglomerate and cell calcification occurred. (2) Scanning electron microscope: At 5 days after co-culture, no cell adhesion appeared on the the tantalum rod surface. At 10 days after co-culture, the cells scattered on the surface of tantalum rod, but there was no interconnection between them. After 15 days, cells were polygon shaped and connected into pieces. It could be seen that the cells secreted large amounts of collagen fibers, and the cells that were fusiform and polygon shaped were surrounded by a great amount of extracellular matrice. Bone marrow mesenchymal stem cells appear to have good adhesion and proliferation capability on the surface of tantalum rod. Figures and Tables | References | Related Articles | Metrics

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Insight into nano chitosan effects on MC3T3-E1 cell growth Wang Li-ting, Zhou Gang, Fan Yu-bo 2013, 17 (42):  7375-7381.  doi: 10.3969/j.issn.2095-4344.2013.42.006 Abstract ( 457 )   PDF (2204KB) ( 548 )   Save BACKGROUND: Acute toxicity in vivo experiments in previous studies has been confirmed that the median lethal dose of chitosan microcapsules is higher than 2 000 mg/kg, but the specific pathogenic mechanism is unclear. OBJECTIVE: To explore the influence of nano chitosan on MC3T3-E1 cell growth as a bone substitute material, as well as the physiological function of rats. METHODS: MC3T3-E1 cells were respectively cultured in Dulbecco’s modified Eagle’s medium with different concentrations of chitosan nanoparticles (0, 10 mg/L, 100 mg/L, 1 g/L, 10 g/L). The absorbance values were determined. Changes in MC3T3-E1 cell morphology were observed by scanning electron microscope after 24 hours culture. 10 g/L nano chitosan suspension was prepared using PBS. Two different doses of nano chitosan suspension (166.67 and 16.67 mg/kg body weight) with PBS were injected intraperitoneally into Sprague-Dawley rats, three times a week, for 4 weeks. The control group was injected with equal volume of physiologic saline. Serum biochemical markers were detected to analyze the functions of liver and kidney of rats. Moreover, histopathology slices were observed to evaluate the morphological changes of tissue and inflammatory infiltration. RESULTS AND CONCLUSION: 10 mg/L, 100 mg/L, 1 g/L, 10 g/L nano chitosan suspensions were found growth inhibition in MC3T3-E1 cells as compared with the control group (P < 0.05). The reunion of chitosan was observed in the cytoplasm of MC3T3-E1 cells by transmission electron microscopy. On the cell surface, pseudopodia formed, wavy undulating membrane, nucleus degeneration, fragmentation and condensation were found. Compared with the control group, blood urea nitrogen, Na+ levels were significantly increased in rats injected with nano chitosan suspension at two dosages, but the K+ level in the high concentration group was decreased significantly (P < 0.05). Cell apoptosis was found in the liver and renal tissue in a dose-dependent manner. It suggests that apoptosis may be the possible mechanism of nano chitosan toxicity, and normal physiological function may be impacted over a certain dose. Figures and Tables | References | Related Articles | Metrics

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Improved performance of glass ionomer cement with nano-hydroxyapatite Feng Yao, Feng Si-cong, Wang Jian-ping, Yang Yu-juan 2013, 17 (42):  7382-7388.  doi: 10.3969/j.issn.2095-4344.2013.42.007 Abstract ( 312 )   PDF (2250KB) ( 410 )   Save BACKGROUND: The glass ionomer cement has good biological stability and can sustain the release of fluoride, which has been used as dental repair materials. But because of its low mechanical strength, the glass ionomer cement is confined to the front teeth and other parts with smaller force. OBJECTIVE: To analyze the compressive strength, microleakage and other physical performances of Fuji IX glass ionomer cement after the addition of 8% modified nano-hydroxyapatite. METHODS: (1) Universal testing machine was applied to detect the compressive strength of Fuji IX glass ionomer cement, Fuji IX glass ionomer cement added with 8% modified nano-hydroxyapatite, and super glass ionomer to fill the stainless steel cylinder. (2) Fuji IX glass ionomer cement, Fuji IX glass ionomer cement with 8% modified nano-hydroxyapatite and super glass ionomer were used to fill the tooth cavity; then, the microleakage was detected. (3) Fuji IX glass ionomer cement, Fuji IX glass ionomer cement added with 8% modified nano-hydroxyapatite, and super glass ionomer were used to fill stainless steel rectangular specimens. Then, universal material testing machine was applied to detect the bending strength value.   RESULTS AND CONCLUSION: The compressive strength, microleakage, and bending strength of specimens filled with Fuji IX glass ionomer cement the addition of 8% modified nano-hydroxyapatite were better than the other two groups, and Fuji IX glass ionomer cement was superior to the super glass ionomer in the compressive strength, microleakage and bending strength of filled specimens. It is shown that Fuji IX glass ionomer cement after addition of 8% improved nano-hydroxyapatite can improve the compressive strength and microleakage. Figures and Tables | References | Related Articles | Metrics

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Constructing a tissue-engineered dental root by seeding dental papilla cells into poly(lactic-co-glycolic acid)/sodium alginate hydrogel Guo Hong-yan, Wang Xiao-ling, Xu Peng, Zhu Xiao-ying, Yang Cheng 2013, 17 (42):  7389-7395.  doi: 10.3969/j.issn.2095-4344.2013.42.008 Abstract ( 289 )   PDF (2353KB) ( 457 )   Save BACKGROUND: Studies addressing reconstruction of tooth tissue engineering have shown that tooth structure can be constructed using tissue engineering technology. Tooth root and its periodontal attachment are critical for tooth survival and functions, based on which, whether we can target root tissues with simple structure for tissue engineering construction by bypassing a complex dental tissue engineering concept with the structural integrity? OBJECTIVE: To construct a tissue-engineered dental root by seeding dental papilla cells, as seed cells, into poly(lactic-co-glycolic acid)/sodium alginate hydrogel. METHODS: Rabbit dental papilla cells were isolated and cultured. The cells were then mixed with 1% sodium alginate hydrogel at a final density of 6×109/L. The cell suspension was seeded into a poly(lactic-co-glycolic acid) scaffold with predetermined shape of human tooth and solidified with calcium chloride. Finally, the cell-scaffold composites were subcutaneously implanted into the back of nude mice. The specimens were harvested after 4 and 8 weeks respectively and processed for gross inspection, X-ray and CT examination and histological observation. RESULTS AND CONCLUSION: The newly formed tissue kept the original shape of human dental root 4 and    8 weeks post-implantation. After 4 weeks of implantation, the specimen density was low; the root implants appeared to be incompletely mineralized, alginate hydrogels were degraded, but the copolymer scaffold was not degraded; a number of dentin-like structure appeared, and a fibrous membrane structure was visible on the surface of specimens parallel to the root surface, but the structure was not continuous, and no pulp cavity formed. After 8 weeks, the newly formed tissue was highly mineralized close to root tissue of the nature tooth; the copolymer scaffold was mostly degraded; specimens appeared to have a large number of mature dentin-like structure, and form continuous fibers membrane on the surface parallel to the root surface, below which, cementum-like structure formed. Artificial dental root with biologically similar structures of human dental roots can be constructed using the method of tissue engineering. Figures and Tables | References | Related Articles | Metrics

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Mechanical properties of cobalt-chromium alloys containing different proportion of once-used alloys after recasts Xiao Yue, Ren Dan-dan, Wang Dan 2013, 17 (42):  7396-7401.  doi: 10.3969/j.issn.2095-4344.2013.42.009 Abstract ( 493 )   PDF (2074KB) ( 484 )   Save BACKGROUND: There are numerous studies about mechanical changes of recast cobalt-chromium ceramic alloys. However, little is reported on the mechanical properties of cobalt-chromium ceramic alloys containing once-used alloys after recasts. OBJECTIVE: To study the effects of different proportion of once-used alloys to recasting cobalt-chromium alloys on their mechanical properties, including tensile strength, yield strength, elongation and hardness. METHODS: Cobalt-chromium alloys cast samples were prepared and recast for three times (40% once-used alloys were added per time). The tensile strength, 0.2% yield strength, percentage of elongation, flexural strength and Vickers hardness of each specimen were measured. In addition, microscopic metallographic observation was done. RESULTS AND CONCLUSION: Being recast for three times, cobalt-chromiun alloys showed no significant differences on their tensile strength, 0.2% yield strength, percentage of elongation, flexural strength and Vickers hardness. GenerationⅠalloy samples had uniform size, small diameter and small carbide size distributing along the grain boundary, mainly exhibiting spherical and irregular wormlike forms. Generations Ⅱ and Ⅲ samples were uniform in shape, but crystal grains were coarsened a little. Carbide from Generation IV samples began to be coarsened, irregular wormlike carbides were increased in amount, and a few of non-metallic inclusions could be found in grains. Cobalt-chromium alloys can be recast after addition of 40% once-used alloys for three times at least in air environment, without decrease of the mechanical properties. Figures and Tables | References | Related Articles | Metrics

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Effect of high-pressure steam sterilization on two kinds of orthodontic distal end cutters Wang Jing, Cao Shuai, Wang Pu, Zhang Kai-liang, Cao Bao-cheng 2013, 17 (42):  7402-7407.  doi: 10.3969/j.issn.2095-4344.2013.42.010 Abstract ( 371 )   PDF (754KB) ( 519 )   Save BACKGROUND: Steam sterilization is a commonly used oral clinical method of disinfection, but whether it would produce more significant impact on equipments waiting for sterilization has been controversial. OBJECTIVE: To investigate the effect of autoclave on two kinds of orthodontic distal end cutters by comparing shearing force and corrosion after sterilization. METHODS: Tiantian (n=15) and 3M (n=15) distal end cutters commonly used in orthodontic treatment were chosen for testing and divided into three groups, respectively. Three groups for each kind of cutter were treated with high-pressure steam sterilization, steam sterilization+extraoral shear, and steam sterilization+intraoral shear, respectively. The shearing force and metallography of the distal end cutters were recorded after 0, 20, 40, and 60 cycles of sterilization. An energy dispersive spectrometer was used to scan the surfaces of the working edges of the distal end cutters after 60 cycles. RESULTS AND CONCLUSION: It was found that with an increase in the number of sterilization cycles, the shear force and extent of corrosion increased in all six groups of distal end cutters, but the situation was worse for Tiantian cutters than for 3M cutters. It was found that the difference of shear force between the Tiantian autoclave group and 3M autoclave group was statistically significant (P < 0.05) after 20, 40, and 60 sterilization cycles. Meanwhile, the metallography showed that different degrees of discoloration and rust spots appeared on the work edges of the two brands of distal end cutters with an increase in the number of sterilization cycles, but the corrosion of the Tiantian distal-end cutter was more widespread, and even work-edge defects appeared. The carbon content of the Tiantian distal-end cutter was higher than that of the 3M cutter (P < 0.05), but the chromium content was higher in the 3M cutter (P < 0.05). In addition, aluminum and titanium elements only existed in the 3M cutter. The use of the autoclave affected the distal end cutters in terms of shearing force and corrosion, but the effect on 3M distal end cutters was obviously less than that on Tiantian cutters. Figures and Tables | References | Related Articles | Metrics

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Hero642 nickel-titanium rotary instrument for single-visit root canal treatment Zhang Wei-wei, Jin Fang, Su Yi 2013, 17 (42):  7408-7413.  doi: 10.3969/j.issn.2095-4344.2013.42.011 Abstract ( 814 )   PDF (2205KB) ( 631 )   Save BACKGROUND: Several studies have shown that Hero642 is a rotary nickel-titanium file with high safe performance, and its ability of root canal shaping is good. OBJECTIVE: To observe the clinical effect of single-visit root canal treatment using Hero642 nickel-titanium rotary instrument on teeth with chronic pulpitis and apical periodontitis.   METHODS: Totally 400 teeth with chronic pulpitis and apical periodontitis were operated by Hero642 nickel-titanium rotary instrument and nickel-titanium hand file, respectively. The efficiency of root canal preparation was taken. Pain reactions were recorded 1 week after operation and curative effects were evaluated 2 years after root canal treatment. Rates of pain and success were calculated at 1 week and 2 years after treatment, respectively.  RESULTS AND CONCLUSION: The average time for root canal preparation was (3.57±0.76) minutes in the Hero642 group and (7.62±0.25) minutes in the hand file group, and there was a significant difference between the two groups (P < 0.01). After 1 week of treatment, the pain rates were 3.5% and 22.8% in the two groups, respectively, showing a significant difference (P < 0.01). Two-year follow-up was performed, and ratios of success were 94.4% in the Hero642 group and 92.4% in the hand file group, but there was no difference between the two groups. Hero642 nickel-titanium rotary instrument for single-visit root canal treatment showed excellent efficiency on clinical treatment, reduced treatment period and had less postoperative reactions. Figures and Tables | References | Related Articles | Metrics

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Biocompatibility of magnetic chitosan microspheres Wang Zi-yu, Dong Ju, Zhang Dong-sheng 2013, 17 (42):  7414-7419.  doi: 10.3969/j.issn.2095-4344.2013.42.012 Abstract ( 225 )   PDF (2158KB) ( 497 )   Save BACKGROUND: Chitosan modification for magnetic iron oxide nanoparticles can improve the agglomeration and stability of magnetic iron oxide nanoparticles, and in addition, it can be used for tumor hyperthermia and gene therapy in the future. OBJECTIVE: To explore the biocompatibility of magnetic chitosan microspheres which have the potential application in tumor hyperthermia and gene therapy. METHODS: Magnetic iron oxide nanoparticles were prepared using the modified chemical precipitation. Phacoemulsification method was used to add chitosan into magnetic iron oxide nanoparticles in the preparation of magnetic chitosan microspheres. Then, the following tests were performed. (1) Cytotoxicity test: L-929 cells were cultured in 1640 medium, polyacrylamide monomer solution, 100%, 75%, 50%, 25% of magnetic chitosan microsphere extracts. (2) Hemolysis test: Magnetic chitosan microspheres leaching solution, saline and distilled water were added. (3) Micronucleus test: Kunming mice were intraperitoneally injected with magnetic chitosan microspheres suspension containing 5, 3.75, 2.5, 1.25 g/kg iron oxide magnetic fluid, cyclophosphamide and saline, respectively. RESULTS AND CONCLUSION: Magnetic chitosan microspheres of 200-300 nm in diameter had an increased dispersion effect. The result of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that the toxicity of the material on L-929 cell lines belonged to no cytotoxicity. In the hemolysis test, the hemolysis rate of magnetic chitosan microspheres was 0.69% far less than 5%. In the micronucleus test, magnetic chitosan microspheres suspension did not cause DNA fragmentation and aneuploidy, and did not result in genetic toxicological effects produced by micronuclei. The magnetic chitosan microspheres did not appear with cacogenesis and mutagenesis. From the results, magnetic chitosan microspheres are a kind of high biocompatibility material. Figures and Tables | References | Related Articles | Metrics

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Neuron-like differentiation of mesenchymal stem cells induced by quaternary chitosan thermosensitive hydrogel scaffolds combined with glial cell line-derived neurotrophic factor Huang Cheng, Yang Jian-dong, Feng Xin-min, Li Guang-feng, Li Yi-nan, Xiao Hai-xiang, Sun Yu 2013, 17 (42):  7420-7426.  doi: 10.3969/j.issn.2095-4344.2013.42.013 Abstract ( 263 )   PDF (2250KB) ( 534 )   Save BACKGROUND: In recent years, chitosan-based thermosensitive hydrogel, as scaffold materials, have received more and more attentions in the field of tissue repair because of good biocompatibility, biodegradability and drug-sustained release. OBJECTIVE: To explore the directed differentiation and growth of rat bone marrow mesenchymal stem cells on the quaternary chitosan thermosensitive hydrogel scaffold and to look for more ideal tissue engineering materials for the treatment of nervous system damage. METHODS: The thermosensitive hygrogel scaffold was prepared using hydroxypropyltrimethyl ammonium chloride chitosan (HACC) and β-glycerophosphate (β-GP). The spatial structure of scaffold was observed by scanning electronic microscope. Effect of leaching liquor from the HACC/β-GP scaffold on the viability of bone marrow mesenchymal stem cells was detected by (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The albumin from bovine serum was combined with the scaffold, and the slow-release effect of the scaffold was detected by ultraviolet absorption spectrometry. Bone marrow mesenchymal stem cells were incubated onto the compound scaffold at 3 passages. The adhesion, growth and differentiation of bone marrow mesenchymal stem cells on the compound scaffold were observed by the scanning electron microscope. Neuron-specific enolase was detected by immunofluorescence. RESULTS AND CONCLUSION: The porosity and thermal sensitivity of HACC/β-GP scaffold and slow-release effect of glial cell line-derived neurotrophic factor were apparent. The results of MTT showed that the compound scaffold cannot take apparent negative effects to the proliferation of bone marrow mesenchymal stem cells. After inoculation, bone marrow mesenchymal stem cells permeated the porous structure of the scaffold and adhered to the scaffold. Under the role of glial cell line-derived neurotrophic factor, bone marrow mesenchymal stem cells showed neuron-like cell morphology and cells co-cultured with the compound scaffold expressed the marker of neurons, neuron-specific enolase. Under the role of slow-release glial cell line-derived neurotrophic factor, bone marrow mesenchymal stem cells can grow well in vitro and differentiate into neuron-like cells on the HACC/β-GP scaffold. Figures and Tables | References | Related Articles | Metrics

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Co-transplantation of controlled release glial cell line-derived neurotrophic factor and bone marrow mesenchymal stem cells-derived neuron-like cells reduces glial scars after spinal cord injury Liu Xiao-gang, Deng Yu-bin, Cai Hui, Zhang Xin-peng, Ma Yu-lin, Wei Ke-xin 2013, 17 (42):  7427-7434.  doi: 10.3969/j.issn.2095-4344.2013.42.014 Abstract ( 244 )   PDF (2447KB) ( 500 )   Save BACKGROUND: Previous studies have demonstrated that transplantation of controlled release glial cell line-derived neurotrophic factor and bone marrow mesenchymal stem cells-derived neuron-like cells can effectively promote the motor function and sensory function recovery of rhesus monkeys with spinal cord injury. OBJECTIVE: To validate whether co-transplantation of controlled release glial cell line-derived neurotrophic factor and bone marrow mesenchymal stem cells-derived neuron-like cells exhibits better protective effects on spinal cord glial scar of rhesus monkeys with spinal cord injury than cell transplantation alone. METHODS: Twelve rhesus monkeys were collected to prepare animal models of acute severe spinal cord injury using modified Allen’s method, and then randomly divided into three groups: experimental group, co-transplantation of controlled release glial cell line-derived neurotrophic factor and bone marrow mesenchymal stem cells-derived neuron-like cells; control group, simple transplantation of bone marrow mesenchymal stem cells-derived neuron-like cells; blank control group, PBS. After 5 months, paraffin specimens of the spinal cord were made for detection of morphological and compositional characteristics of glial scar, regeneration of nerve fibers in the scar, glial scar area, and average absorbance of glial fibrillary acidic protein. RESULTS AND CONCLUSION: Glial scar in the injured spinal cord was composed of astrocytes and histocytes. Less spinal cord glial scar area and lower absorbance value could be observed in the experimental and control groups as compared with the blank control group (P < 0.05). In addition, in the blank control group, neurofilament negative fibers could be observed in the glial scar, and astrocytes proliferated obviously. The experimental and control groups showed less fibers passed through the scar area. The glial scar area and average absorbance in the experimental group was lower than that in the control group (P< 0.05). These findings suggest that compared with simple transplantation of bone marrow mesenchymal stem cells-derived neuron-like cells, co-transplantation of controlled release glial cell line-derived neurotrophic factor and bone marrow mesenchymal stem cells-derived neuron-like cells shows better protective effects spinal tissue structure after spinal cord injury, which may be one of mechanisms by which the number of glial scars is reduced to a greater extent. Figures and Tables | References | Related Articles | Metrics

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Preparation of a thermosensitive hydrogel scaffold combined with bone marrow mesenchymal stem cells Li Yi-nan, Li Guang-feng, Feng Xin-min, Huang Cheng, Xiao Hai-xiang, Yang Jian-dong 2013, 17 (42):  7435-7441.  doi: 10.3969/j.issn.2095-4344.2013.42.015 Abstract ( 298 )   PDF (2365KB) ( 544 )   Save BACKGROUND: Scaffolds made of chitosan and its derivatives play an important role in cell migration and axonal regeneration. Chitosan and its derivatives have good histocompatibility, which is easy to make stem cells grow on the surface, thereby having a more broad application prospect in the nerve tissue engineering. OBJECTIVE: To fabricate a thermosensitive hydrogel scaffold using chitosan/hydroxypropyltrimethyl ammonium chloride chitosan/sodium glycerophosphate (CS/HACC/GP), which is suitable for cell growth, and then, to observe the growth and proliferation of bone marrow mesenchymal stem cells on the scaffold. METHODS: Chitosan was modified using quaternary ammonium salt and confirmed by Fourier transform infrared spectroscopy. The chitosan and quaternary ammonium salt of chitosan was mixed at a ratio of 8:1 to successfully prepare stable CS/HACC/GP thermosensitive hydrogel scaffold. Then, the gelling was observed, and biosafety test was conducted. RESULTS AND CONCLUSION: Fourier transform infrared spectroscopy showed the characteristic peak of quaternary ammonium groups. Cytotoxicity test showed that rat bone marrow mesenchymal stem cells cultured in hydrogel extracts had no toxicity. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test showed that hydrogel extracts exerted no significant effect on the increase in body weight, and the biological safety of the scaffold  was good. Under the scanning electron microscopy, bone marrow-derived mesenchymal stem cells grew and proliferated normally in the scaffold. The results confirmed that the CS/HACC/GP thermosensitive hydrogel scaffold was successfully prepared in the experiment, which is suitable for the growth and proliferation of bone marrow mesenchymal stem cells. Figures and Tables | References | Related Articles | Metrics

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Interaction among a three-dimensional scaffold, vessels and cells in the culture of tumor cells Hu Xue-feng, Zheng Li, Zhao Jin-min 2013, 17 (42):  7442-7448.  doi: 10.3969/j.issn.2095-4344.2013.42.016 Abstract ( 377 )   PDF (2572KB) ( 629 )   Save BACKGROUND: The tumor tissue engineering can build an integrated culture model to fully simulate the in vivo microenvironment of tumor growth, which can be used to study tumor developmental dynamics and related treatment strategies. OBJECTIVE: To review the three-dimensional culture of tumor cells using tumor engineering technology. METHODS: PubMed database was retrieved for articles related to tumor engineering, three-dimensional culture of tumor cells, biological scaffold materials and tumor microenvironment published from January 1992 to March 2013. RESULTS AND CONCLUSION: Three-dimensional culture, because of its reproducible tissue and cell growth in vivo, has become an important platform for study of tumor resistance, invasiveness and tumor microenvironment. The three-dimensional culture has showed a trend to gradually replace the flat culture technique in many fields, and provides a research platform which is very close to in vivo environment. In recent years, with the development of tumor engineering, a variety of new polymer materials have been used in the three-dimensional culture of tumor cells. Three-dimensional culture technology is becoming a hotspot in the field of tumor biology, in which, using a variety of methods and materials, the cells show a growth in the spatial manner to form a biological support or matrix similar to in vivo growth environment. Biomaterials have become the soil on which seed cells can grow well, and plays an alternative to the extracellular matrix or the matrix of tissues and organs in the tumor engineering. Therefore, the three-dimensional cell culture has been widely used in cancer research, which has become a powerful tool to tumor drug resistance, angiogenesis, cell-cell interaction, signal transduction, stem cells and other research. Figures and Tables | References | Related Articles | Metrics

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Membrane guided bone regeneration technology for treatment of bone defects: How better to be used in clinic?  Wang Lei, Yu De-tao 2013, 17 (42):  7449-7454.  doi: 10.3969/j.issn.2095-4344.2013.42.017 Abstract ( 328 )   PDF (610KB) ( 455 )   Save BACKGROUND: Membrane guided bone regeneration technology has become an important method in repairing bone defects. With the deepening of the research, related concept and the mechanism of membrane guided bone regeneration have been gradually confirmed, but there are still some unresolved issues. OBJECTIVE: To review the classification of membrane tubes, performance, disadvantages and advantages in membrane guided bone regeneration, as well as some unresolved issues in application and research. METHODS: The first author searched PubMed and CNKI databases to retrieve articles about the discovery of membrane guided bone regeneration and the concepts, classification of membrane tubes, performance, disadvantages and advantages during bone defect treatment, which were published from 1963 to 2013. The key words were “guided bone regeneration, guided tissue regeneration, bone defect treatment” in English and Chinese, respectively. RESULTS AND CONCLUSION: Membrane guided bone regeneration technique is a most promising treatment for bone defects, but for the treatment of long tubular bone defects, it is still in the experimental stage. Currently, there is no membrane tube for long-segment bone defects. According to the material sources, the membrane tubes can be divided into: non-biological material, such as polytetrafluoroethylene, polylactic acid, silica gel, titanium film; biological materials, such as collagen membrane, chitin membrane, polyhydroxybutyrate. The membrane tubes can also be classified into nondegradable materials and biodegradable materials. Biodegradable materials have good histocompatibility and no cytotoxicity, which can degrade in a certain period after implantation; part of the membrane can also allow free exchange of tissue fluid and nutritional substances. But there are still some shortcomings that the degradation time is difficult to control and the volume is difficultly maintained under the membrane tube. New bone formation in non-biodegradable materials is complete. In the process of osteogenesis, the membrane tube cannot be absorbed and has to be removed secondarily, though it has good histocompatibility and better therapeutic outcomes. In the future, we should further improve membrane performance, so that the membrane tube can play a dual role, fixation and guided bone regeneration; a series of animal studies should be conducted to study the effect of stress on the membrane tube and osseointegration within the membrane tube, to master the law of osseointegration of membrane tubes, thereby providing evidence for repair of long tubular bone defects. Figures and Tables | References | Related Articles | Metrics

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Polypeptide modified coating, a bone tissue engineering material, is used for treatment of osteoporosis Wang Cong, Yuan Wen, Wu Xiao-dong, Ao Hai-yong 2013, 17 (42):  7455-7461.  doi: 10.3969/j.issn.2095-4344.2013.42.018 Abstract ( 341 )   PDF (677KB) ( 705 )   Save BACKGROUND: The biological substances fixed onto the implant surface, including specific proteins, enzymes, polypeptides, could promote the proliferation and differentiation of osteogenic cells in order to achieve a good osteogenic effect. OBJECTIVE: To introduce the biological characteristics of the arginine-glycine-aspartic acid (RGD) peptides, cell biological behavior and implant osseointegration in osteoporosis. METHODS: Authors retrieved the relevant articles in PubMed database (January 1984 to January 2013), Wanfang database (January 2002 to December 2012) and CHKD database (January 2002 to December 2012) using the key words “RGD peptides, osteoporosis, bone marrow mesenchymal stem cells, osseointegration, osteoblast, induced differentiation”. Papers were included concerning the biological characteristics of RGD peptides, the biological behavior of cells and the bone-implant integration in osteoporosis. RESULTS AND CONCLUSION: Osseointegration on the surface between implant and bone tissue can be further  improved by grafting biologically active substance. Bionics modification, to simulate the extracellular matrix environment in vivo, can promote cell adhesion and growth, which is an effective way to improve osseointegration and is also an important direction of research in the field of tissue engineering recently. The future research is focused on designing specific and efficient polypeptides and simple and effective fixation methods. Figures and Tables | References | Related Articles | Metrics

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Clinical application of bioabsorbable polymer interbody fusion cage Wang Le, Liu Shao-yu 2013, 17 (42):  7462-7468.  doi: 10.3969/j.issn.2095-4344.2013.42.019 Abstract ( 225 )   PDF (772KB) ( 425 )   Save BACKGROUND: Bioabsorbable polymer materials used in interbody fusion are currently a hot research, and there is still no consensus. OBJECTIVE: To summarize the basic research and clinical application of bioabsorbable polymer interbody fusion cages. METHODS: A search of literatures in the database of Wanfang, VIP and PubMed databases from January 1989 to June 2012 was performed with the key words of “intervertebral fusion; bioabsorbable; spine; animal experiment; clinical research” in Chinese and English, respectively. All the literatures concerning bioabsorbable polymer interbody fusion cage were extensively reviewed, and current developments in the basic research and the clinical application of bioabsorbable polymer interbody fusion cage were investigated. RESULTS AND CONCLUSION: Basic researches show that bioabsorbable polymer cage can effectively promote interbody fusion, the main defect is the delayed inflammatory response and bulk erosion, and the degradation and fusion speed, mechanical strength and porosity need further studies. At present, the hybrid copolymer of polylactic acid and its derivatives is used in clinic and relevant research is being carried out. The main advantage of the material is that it is of flexibility to change parameters when used in fusion for different needs, but a good blood supply to tissues around the fusion cage and the osteogenesis effect are very important. Scaffold porosity and other key parameters can affect the mechanical properties of fusion cage to provide sufficient space to meet the requirement of cell migration, angiogenesis, thereby promoting bone fusion, under the necessary pressure load. So, to find the optimal combination of parameters in the field of bone tissue engineering is still a challenge. Figures and Tables | References | Related Articles | Metrics

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Fluorouracil sustained release agent in the treatment of advanced gastric cancer Zhang Bin, Wang Bing-ji, Li Zeng-cai, Liu Xian-zhong, Wang Xuan 2013, 17 (42):  7469-7474.  doi: 10.3969/j.issn.2095-4344.2013.42.020 Abstract ( 245 )   PDF (729KB) ( 413 )   Save BACKGROUND: Fluorouracil sustained-release agent is a commonly used anti-cancer sustained-release drug, which has a good anti-tumor effect. OBJECTIVE: To explore the effect of fluorouracil sustained-release agent in the treatment of gastric cancer. METHODS: Literatures concerning the effect of fluorouracil sustained-release agent in the treatment of gastric cancer were retrieved and analyzed. In the paper, we investigated the preventive effect of fluorouracil sustained-release agent against tumor recurrence and metastasis after radical resection, and followed up the patients who underwent clinical peritoneal implantation of fluorouracil sustained-release agent. We could determine the effect of fluorouracil sustained-release agent in the treatment of advanced gastric cancer by observing the patient’s symptoms and signs, expression of tumor markers, tumor size and survival rate. RESULTS AND CONCLUSION: After combination therapy of fluorouracil sustained-release agent and arterial infusion chemotherapy adjuvant therapy, the patient’s symptoms and tumor resection rate were significantly improved. The levels of CEA, CA19-9, CA72-4 in the serum of patients significantly reduced, while the apoptosis and necrosis of tumor cells significantly increased. Fluorouracil sustained-release agent could also reduce tumor metastasis and local recurrence, and improve patient survival. Figures and Tables | References | Related Articles | Metrics

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Different types of orthoses in stroke patients with hemiplegia: Functional effects Wang Yan, Xiong Jie 2013, 17 (42):  7475-7480.  doi: 10.3969/j.issn.2095-4344.2013.42.021 Abstract ( 844 )   PDF (788KB) ( 580 )   Save BACKGROUND: The appropriate choice of orthoses based on hemiplegic patient’s condition can improve motor function recovery in stroke patients. OBJECTIVE: To review the motor function recovery of stroke patients with hemiplegia wearing different types of orthoses. METHODS: Application of different types of orthoses in hemiplegic patients was reviewed through access to literature, as well as effects of a variety of orthoses on the recovery of motor functions in hemiplegic patients. RESULTS AND CONCLUSION: Orthoses can reduce limb muscle tension and muscle spasms, and  improve motor function and overall daily living skills in stroke patients with hemiplegia, which play a variety of roles, including stable support, fixed protection, correction of deformity and functional compensation. However, the long-term therapeutic effect of orthoses cannot be verified because of fewer cases, shorter time for therapeutic observation, and the lack of long-term follow-up. It is necessary to perform long-term follow-up for the verification of long-term efficacy of orthoses. Meanwhile, the appropriate timing for removal of orthoses needs further study. Figures and Tables | References | Related Articles | Metrics

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Light-cured resin materials fill the oversized interdental space between maxillary anterior teeth Zhang Yan-jun, Liu Ke-li 2013, 17 (42):  7481-7486.  doi: 10.3969/j.issn.2095-4344.2013.42.022 Abstract ( 636 )   PDF (566KB) ( 401 )   Save BACKGROUND: Light-cured resin is a new kind of material with beautiful color, high strength, wide range of applications, easy-to-use and inexpensive features. Patients are willing to accept it because of less or no grinding of the teeth. OBJECTIVE: To observe the effect of light-cured resin to fill the interdental space between maxillary anterior teeth. METHODS: A total of 32 patients aged 21-52 years were enrolled, 107 teeth with 75 oversized maxillary spaces, including 15 males and 17 females. One space between bilateral central incisors was found in 14 cases; three spaces between bilateral central incisors, left lateral incisor, and left canine were found in three cases; three spaces between bilateral central incisors, right lateral incisor, and right canine were found in two cases; four spaces between left central incisor, left lateral incisor, left canine, right central incisor, and right lateral incisor were found in three cases; three spaces between bilateral central incisors and lateral incisors were found in six cases; four spaces between left central incisor, left lateral incisor, right central incisor, right lateral incisor, and right canine were found in four cases. All the oversized maxillary spaces were filled with light-cured resin. Then, crown morphology, adaptation, color, degree of wear and loosening were observed during follow-up. RESULTS AND CONCLUSION: After 3-year follow-up, 17 of 32 cases were successful in tooth repair: the crown morphology and tooth adaptation were good, and there was no prosthesis loosening or detachment and discoloration. The tooth space was repaired basically in another nine cases: the crown morphology and tooth adaptation were not good enough, no prosthesis loosening or detachment was found, but there were some defects at the gingival margin and contact surface of teeth as well as mild discoloration. Tooth repair failed in the other six cases with worse crown morphology and adaptation, prosthesis loosening or detachment, and severe discoloration, which need to be repaired again. Figures and Tables | References | Related Articles | Metrics

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Two tooth preparation methods to make glass fiber splints for stabilizing loose front teeth: A 5-year clinical observation Han Li-na, Yang De-sheng 2013, 17 (42):  7487-7493.  doi: 10.3969/j.issn.2095-4344.2013.42.023 Abstract ( 318 )   PDF (756KB) ( 551 )   Save BACKGROUND: Studies have found that the glass fiber splint which is embedded into the groove on the lingual surface of the affected tooth plus fluid resin fixation between the gap of mobile teeth can achieve more satisfactory clinical effects on the stabilization of loose front teeth. OBJECTIVE: To observe the clinical effects of glass fiber splints prepared using two tooth preparation methods on splinting loose front teeth and their debonding rate through a 5-year follow-up visit. METHODS: Ninety-four chronic periodontal disease patients, who had received periodontal treatment, were enrolled in this study for their loose front teeth of degree II-III. All the enrolled patients were good candidates for periodontal splinting strictly in accordance with the indications for periodontal splinting. According to whether the fluid resin was used to seal the gap between the mobile teeth, the 96 patients were divided into two groups: patients undergoing glass fiber splint + fluid resin between the mobile teeth served as experimental group, and those only undergoing glass fiber splint as control group. All the patients were followed by regular clinical referral or telephone follow-up for 5 year, to evaluate the fixed effects. RESULTS AND CONCLUSION: During the 5 years of regular clinical referral or telephone follow-up, seven of the 76 cases and 12 of the 18 cases were found in the experimental and control groups, respectively, to have debonding between the abutment and the splint. Compared with the control group, the probing depth and attachment loss of affected teeth were improved significantly (P < 0.05), and the percentage of alveolar bone height accounting for the root length increased significantly in the experimental group (P < 0.05) after 5 years of follow-up. Patients in the experimental group felt comfortable without foreign body sensation. The results confirmed that the glass fiber splinting plus fluid resin fixation between the gap of mobile teeth was a better treatment for loose front teeth during the 5-year follow-up. Figures and Tables | References | Related Articles | Metrics

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Silver ion dressing effects on healing of chronic wound Liu Tao, Xu Hai-dong 2013, 17 (42):  7494-7500.  doi: 10.3969/j.issn.2095-4344.2013.42.024 Abstract ( 695 )   PDF (890KB) ( 1022 )   Save BACKGROUND: Silver ion dressing can reduce tissue necrosis, accelerate the epithelial formation, relieve the patient’s pain during the treatment, and strengthen various growth factors for wound repair, which is based on the theory of wet healing theory. It has obvious advantages for chronic wound healing, such as anti-infection and promoting wound granulation and epithelial hyperplasia. OBJECTIVE: To observe the efficacy of silver ion dressing used in healing of chronic wound. METHODS: A total of 40 patients who had chronic wounds were selected from Tangshan Branch Hospital of Nanjing General Hospital of Nanjing Military Command. All cases were divided into two groups. The treatment group was treated with silver ion dressing, and the control group was treated with routine dressing. Secretions extracted from wound were used for bacterial culture prior to and 7, 14, and 21 days after treatment. Healing condition and velocity were observed and wound pain was assessed using visual analog scale. RESULTS AND CONCLUSION: The detection rate of wound bacteria in the treatment group was significantly lower than that of the control group (P < 0.05). And the time of healing was shorter in the treatment group than the control group (P < 0.05). Wound pain during dressing change was relieved (P < 0.05). Medical costs showed no difference between the two groups (P > 0.05). No adverse reaction occurred in the two groups. These findings indicate that silver ion dressing used in chronic wound healing can prevent infection and promote wound granulation or epithelial hyperplasia. It can effectively promote wound healing and has no bad reaction. Figures and Tables | References | Related Articles | Metrics