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08 June 2022, Volume 26 Issue 16 Previous Issue   

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Comparison of biomechanical properties of calcium phosphate/polymethyl methacrylate composite bone cement and polymethyl methacrylate bone cement Li Shengkai, Li Tao, Wei Chao, Shi Ming 2022, 26 (16):  2461-2466.  doi: 10.12307/2022.241 Abstract ( 686 )   PDF (21196KB) ( 67 )   Save BACKGROUND: Polymethyl methacrylate (PMMA) is the most widely used bone cement in vertebral body reinforcement, but it still has some defects such as excessive elastic modulus. The in vitro mechanical test of bone cement for how to reduce its elastic modulus has a certain significance for guiding clinical practice. OBJECTIVE: To measure compressive strength of PMMA bone cement and its composite bone cement after adding self-solidifying calcium phosphate artificial bone, and evaluate the effect of adding calcium phosphate artificial bone on the elastic modulus of PMMA bone cement. METHODS: PMMA (100%), calcium phosphate/PMMA (87%) and calcium phosphate/PMMA (76%) bone cement were prepared by adding calcium phosphate artificial bone (0, 4, 8 g) and PMMA (26 g) to liquid phase monomer, respectively, and injected into the standard experimental module of human cancellous bone to prepare human osteoporosis model. The ultimate compressive strength and elastic modulus of each model were measured by standard compression test. PMMA (100%), calcium phosphate/PMMA (87%) and calcium phosphate/PMMA (76%) bone cement were prepared into cylindrical standard bone cement specimens; the highest curing temperature and the time required for each sample to reach the highest curing temperature were determined; and the ultimate compressive strength and elastic modulus of each model were measured by standard compression test. RESULTS AND CONCLUSION: (1) In the bone cement standard specimen model, the maximum compressive strength and elastic modulus of calcium phosphate/PMMA (87%) group and calcium phosphate/PMMA (76%) group were lower than those of PMMA (100%) group (P < 0.05), and the compressive strength of calcium phosphate/PMMA (76%) group was lower than that of calcium phosphate/PMMA (87%) (P < 0.05). The maximum curing temperature of calcium phosphate/PMMA composite bone cement was lower than that of PMMA bone cement, and there was no significant change in solidification time. (2) In the osteoporosis model, the maximum compressive strength of calcium phosphate/PMMA (87%) group and calcium phosphate/PMMA (76%) group was lower than that of PMMA (100%) group (P < 0.05); and the elastic modulus of calcium phosphate/PMMA (76%) group was lower than that of calcium phosphate/PMMA (87%) group (P < 0.05). (3) The results show that adding calcium phosphate to PMMA bone cement can reduce the elastic modulus. In a certain range, calcium phosphate/PMMA composite bone cement has better mechanical and structural properties than PMMA bone cement, and there is no obvious change in controllability, so it can be used for vertebral body reinforcement. Figures and Tables | References | Related Articles | Metrics

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Robot-assisted percutaneous vertebroplasty in the treatment of pathological fractures of thoracolumbar multivertebra Yu Yang, Tang Liuyi, Hu Jiang, Wan Lun, Zhang Wei, Lin Shu, Wang Fei 2022, 26 (16):  2467-2472.  doi: 10.12307/2022.242 Abstract ( 482 )   PDF (19781KB) ( 78 )   Save BACKGROUND: Vertebroplasty can effectively treat spinal pathological fractures, but the side effects and bone cement leakage caused by this operation are often reported. OBJECTIVE: To investigate the clinical efficacy of robot-assisted percutaneous vertebroplasty in the treatment of pathological fractures of thoracic and lumbar vertebrae. METHODS: From June 2017 to December 2019, 25 patients with pathological fractures of thoracolumbar vertebrae in the Sichuan Provincial People’s Hospital were retrospectively analyzed, including 7 males and 18 females, aged from 57 to 80 years old. There were 10 cases of osteoporotic vertebral fracture, 15 cases of vertebral tumor, 16 cases of 3 diseased vertebrae, 6 cases of 4 diseased vertebrae, and 3 cases of more than 5 diseased vertebrae. There were 13 patients (50 vertebrae) with robot assisted vertebroplasty (robot group), and 12 patients (38 vertebrae) with freehand vertebroplasty (conventional group). The number of puncture, fluoroscopy, operation time, intraoperative blood loss, bone cement distribution, bone cement leakage and intraoperative radiation dose of the operator were recorded and compared between the two groups. Oswestry disability index and visual analogue scale scores of the patients were recorded and compared before and after operation. This study was approved by Ethics Committee of Sichuan Provincial People’s Hospital. RESULTS AND CONCLUSION: (1) The operation time, number of puncture, fluoroscopy, intraoperative blood loss, intraoperative radiation dose, and bone cement leakage in the robot group were all lower than those in the conventional group (P < 0.05). The bone cement distribution was better in the robot group than that in the conventional group (P < 0.05). (2) Oswestry disability index and visual analogue scale scores were significantly improved in the two groups at postoperative 2 days compared with those preoperatively (P < 0.05). Visual analogue scale score and Oswestry disability index of the robot group and the conventional group showed no statistical significance before and 2 days after surgery (P > 0.05). (3) For patients with multiple vertebral pathological fractures, robot-assisted vertebroplasty improves the accuracy of puncture, which can not only reduce the puncture injury of patients, obtain satisfactory bone cement dispersion and reduce bone cement leakage, but also reduce the operator’s radiation exposure and obtain satisfactory clinical efficacy. Figures and Tables | References | Related Articles | Metrics

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Preparation and properties of carboxymethylated cotton linters hemostatic gauze Liu Xiaojun, Xu Yuyin, Liu Kangbo, Zhou Jing, Han Ying, Xiong Yue, Tian Yuan 2022, 26 (16):  2473-2479.  doi: 10.12307/2022.243 Abstract ( 631 )   PDF (34172KB) ( 77 )   Save BACKGROUND: At present, cotton lint and its modified products have been widely concerned in cleaning water or oil pollution, but the preparation of cotton lint for hemostatic gauze has not been reported.  OBJECTIVE: To prepare a kind of carboxymethylated cotton linters hemostatic gauze by modifying cotton linters gauze and characterize it. METHODS:  Carboxymethylated cotton linters cotton gauze was prepared by chemical modification. Infrared spectrometer, scanning electron microscope and X-ray diffractometer were used to characterize the morphology and structure of cotton linter gauze group (raw material), carboxymethylated cotton linter hemostatic gauze (experimental group) and absorbable hemostatic gauze (control group). The physical and chemical indexes were measured by water absorption, mechanical properties, gelation rate and solubility. The hemostatic performance was tested by measuring whole blood coagulation time. At last, the cytocompatibility of gauze in the experimental group was evaluated by cytotoxicity test in vitro.   RESULTS AND CONCLUSION: (1) The result of infrared spectrum showed that carboxymethylation occurred in the gauze from experimental group, The hydrophilic carboxymethyl group was introduced into the fiber structure. X-ray diffraction results showed that compared with the raw material group, the crystal phase of the experimental and the control groups was incomplete with the crystallinity decreased. (2) Scanning electron microscope result showed that the fibers of the raw material group were straight and tightly arranged. In the experimental group, the fiber braiding mode was not changed, but the arrangement was loose, the fiber diameter was increased, and the surface roughness was increased. In the control group, the fiber had a unique weaving mode; the fiber surface was long and thin, smooth and the texture was clear. (3) There was no significant difference in porosity among the three groups (P > 0.05). The water absorption rate of the experimental group was higher than that of the raw material group (P < 0.05) and lower than that of the control group (P < 0.05). (4) Both the experimental group and the control group formed gel within 30 seconds after water absorption, and completely dissolved within 1 hour. (5) The tensile strength of the experimental group was lower than that of the raw material group (P < 0.05), but there was no significant difference between the experimental and the control groups (P > 0.05). The fracture elongation of the experimental group was higher than that of the raw material group (P < 0.05) and lower than that of the control group (P < 0.05). (6) The blood coagulation time in the experimental group was shorter than that in the raw material group (P < 0.05), while it did not differ from the control group significantly (P > 0.05), indicating that the gauze in the experimental group had good cytocompatibility. (7) The results suggested that carboxymethylated cotton linters hemostatic gauze presented good physical and chemical properties, hemostatic properties and cellular compatibility. Figures and Tables | References | Related Articles | Metrics

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Fabrication and biocompatibility of injectable gelatin-methacryloyl/cartilage-derived matrix particles composite hydrogel scaffold Huang Bo, Chen Mingxue, Peng Liqing, Luo Xujiang, Li Huo, Wang Hao, Tian Qinyu, Lu Xiaobo, Liu Shuyun, Guo Quanyi 2022, 26 (16):  2480-2486.  doi: 10.12307/2022.244 Abstract ( 569 )   PDF (1362KB) ( 270 )   Save BACKGROUND: Articular cartilage regeneration and repair is still a challenging medical problem. The injectable hydrogel scaffold that constructs a biomimetic microenvironment for cell growth is of great significance for the regeneration of articular cartilage.   OBJECTIVE: To prepare injectable gelatin-methacryloyl/cartilage-derived matrix particles (GelMA/CDMPs) composite hydrogel scaffold, and evaluate its biocompatibility. METHODS:  (1) CDMPs were prepared by physical pulverization and chemical enzymatic methods, and GelMA was prepared by the reaction of methacrylic anhydride grafted gelatin. The two were used as raw materials to prepare five different GelMA/CDMP composite hydrogel scaffolds (where the CDMP mass concentrations were 0, 5, 10, 20, and 30 g/L), and the mass concentration of CDMPs with the best mechanical properties was determined through mechanical tests. (2) Rabbit bone marrow mesenchymal stem cells were encapsulated in the GelMA/CDMPs composite hydrogel scaffolds (as the experimental group); bone marrow mesenchymal stem cells were encapsulated in GelMA hydrogel scaffolds (as the control group); both of which were cultured in the chondrogenic medium. The cell viability and cell proliferation of the two groups of stents were evaluated through cell live/dead staining and CCK-8 cell proliferation experiments. The morphology and spreading ability of cells in the scaffolds were observed by cytoskeleton fluorescence staining. The secretion of cartilage matrix of bone marrow mesenchymal stem cells in the scaffolds was evaluated by histological staining and quantitative glycosaminoglycan test.   RESULTS AND CONCLUSION: (1) Mechanical tests showed that compressive modulus of GelMA/CDMPs 10 g/L composite hydrogel scaffolds was significantly higher than that of other groups (P < 0.05). And this concentration was selected for the subsequent experiments. (2) The cell live/dead staining demonstrated that cell viability of bone marrow mesenchymal stem cells in the two groups of scaffolds was above 90% after 1 and 5 days of culture. After 3- and 5-day culture, the cell proliferation of the experimental group was faster than that of the control group (P < 0.05). (3) Fluorescence staining of the cytoskeleton after culture for 7 days showed that the cell morphology in the control group was spherical; and only a small part of the cells formed filopodia. The cell morphology in the experimental group was stretched and showed irregular polygons. (4) After 21 days of culture, histological and immunohistochemical staining showed that the cell morphology of bone marrow mesenchymal stem cells in the two groups of scaffolds was similar to chondrocytes morphology; and more cartilage matrix was secreted by bone marrow mesenchymal stem cells in the experimental group. (5) After 7- and 21-day culture, the content of glycosaminoglycan was significantly higher in the experimental group than that in the control group (P < 0.05). (6) These results suggest that GelMA/CDMPs composite hydrogel scaffold can better mimic the microenvironment of chondrocyte growth, and then promote the growth, proliferation and chondrogenesis of bone marrow mesenchymal stem cells. Figures and Tables | References | Related Articles | Metrics

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Preparation and properties of biodegradable plant polysaccharide hemostatic microspheres Yang Xue, Wang Baoqun, Jiang Xiaowen, Zou Shengcan, Ming Jinfa, Lin Shasha 2022, 26 (16):  2487-2491.  doi: 10.12307/2022.245 Abstract ( 815 )   PDF (847KB) ( 621 )   Save BACKGROUND: Hemostasis is an important part of clinical treatment. Fast and effective hemostasis is necessary to ensure the safety of surgical patients. OBJECTIVE: To prepare a kind of plant polysaccharide hemostatic microsphere with porous structure and its performance evaluation.  METHODS: Porous hemostatic microspheres were prepared from potato starch by gelatinization, emulsification crosslinking, cleaning, and drying technique. The hemostatic performance of the hemostatic microspheres was improved by improving the gelatinization and crosslinking processes of the starches, setting the grouping: group A (gelatinization for 1 hour, crosslinking for 6 hours, group B (gelatinization for 1 hour, crosslinking for 12 hours), group C (gelatinization for        1 hour, crosslinking for 18 hours), group D (gelatinization for 2 hours, crosslinking for 6 hours), group E (gelatinization for 2 hours, crosslinking for 12 hours), and  group F (gelatinization for 2 hours and crosslinking for 18 hours). The listed absorbable hemostatic microspheres were used as controls to examine the microtopography, pH, porosity and in vitro degradation of microspheres in each group. According to the above experimental results, suitable microspheres were selected for hemostasis of liver and spleen in New Zealand rabbits, comparing the sample dosage, hemostasis amount with hemostasis time. RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that group B and group E formed porous microspheres with a stable structure of 50-200 μm in diameter, and the spherical morphology and porosity were better than those of the control group. Except for groups C and E, the pH values of the other samples were in the range of 6.5-7.5, which met the pH requirements. The same quality of samples, the cross-linking time growth and degradation time increased significantly (P < 0.01). Based on the examination of morphological structure, porosity, pH and in vitro degradation in the previous stage, groups A, B, E and the control group were selected for hemostasis experiments. (2) Under the same hemostatic effect, the hemostatic time of microspheres in group E was shorter and less used compared with that in the control group, and the hemostatic effect in group B was not significantly different from that in the control group. (3) The results showed that the porous starch microspheres prepared after gelatinization at 60 °C for 2 hours, emulsification for 45 minutes, and cross-linking for 12 hours had the best hemostatic effect and its degradation time was also relatively short, and its performance was superior to that of listed products.  Figures and Tables | References | Related Articles | Metrics

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Influence of lay-down angles on mechanical properties of three-dimensional printed polycaprolactone scaffolds Liu Jiali, Suo Hairui, Yang Han, Wang Ling, Xu Mingen 2022, 26 (16):  2492-2497.  doi: 10.12307/2022.246 Abstract ( 533 )   PDF (1714KB) ( 127 )   Save BACKGROUND: Three-dimensional (3D) printed polycaprolactone scaffold is one of the hotspots in recent years. It is difficult to prepare porous scaffolds with appropriate materials and excellent mechanical properties in current studies.   OBJECTIVE: To manufacture 3D porous polycaprolactone scaffolds with different lay-down angles and study their mechanical properties. METHODS:   3D porous polycaprolactone scaffolds with different lay-down angles (0°/90°, 0°/60°, 0°/60°/120°, 0°/45° and 0°/45°/90°/135°) were designed and prepared using 3D printer. The porosity, compression and tensile properties of the scaffold were measured.   RESULTS AND CONCLUSION: (1) There was no significant difference in the porosity of the five scaffolds (P > 0.05). (2) In Z direction compression, there was little difference for polycaprolactone scaffolds with different lay-down angles. (3) In Y direction, the compression of the 0°/45°, 0°/60°, and 0°/90° scaffolds increased with the increase of the filling angle. The compressive modulus and strength of 0°/45°/90°/135° were higher than those of 0°/45°. The compressive modulus and strength of 0°/60°/120° scaffolds were stronger than those of 0°/60°. (4) When the three scaffolds were compressed in X direction, the law of the compression modulus and strength of the scaffold was opposite to those of the compression in the Y direction. Among the five types of scaffolds, the tensile modulus and strength of the 0°/45°/90°/135° scaffolds were the largest, and the tensile modulus and strength of the 0°/90° scaffold were the smallest; the tensile strength and modulus of the 0°/45°, 0°/60°, and 0°/90° scaffolds decreased with the increase of the angle. (5) The results show that the 0°/90° and 0°/60°/120° scaffolds can meet the requirements of the physiological environment with isotropic mechanical properties, and the other three structures can meet the requirements of the anisotropic growth environment of human tissues. Figures and Tables | References | Related Articles | Metrics

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Effect of polymethyl methacrylate/mineralized collagen/Mg-Ca composite material on osteogenic differentiation of mouse preosteoblasts Zhang Hongmei, Sun Xirao, Wang Chengyue 2022, 26 (16):  2498-2503.  doi: 10.12307/2022.247 Abstract ( 438 )   PDF (26021KB) ( 145 )   Save BACKGROUND: The structure of mineralized collagen/Mg-Ca composite prepared by freeze-drying method is loose, and the structural stability of the composite can be enhanced by using polymethyl methacrylate bone cement as the outer strengthening layer. OBJECTIVE: To investigate the effects of polymethyl methacrylate/mineralized collagen/Mg-Ca composite on osteogenic differentiation of MC3T3-E1 cells.   METHODS: The polymethyl methacrylate/mineralized collagen/Mg-Ca and polymethyl methacrylate/mineralized collagen composites were prepared respectively. The MC3T3-E1 cells were directly inoculated on the surface of polymethyl methacrylate/mineralized collagen/Mg-Ca composite (group A), polymethyl methacrylate/mineralized collagen composite (group B) and Mg-Ca alloy (group C). Cells cultured alone were blank controls (group D). The cell adhesion morphology on the material surface was observed under the scanning electron microscope. CCK-8, alkaline phosphatase activity, enzyme linked immunosorbent assay, RT-PCR, and western blot assay were used to analyze the effects of three materials on MC3T3-E1 cell proliferation and osteogenic differentiation.   RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the largest adhesion number of MC3T3-E1 cells on the surface of polymethyl methacrylate/mineralized collagen/Mg-Ca composite, grew well, stretched obviously, pseudopodia extended more, and connected with each other to form a network structure. (2) CCK-8 assay showed that compared with the group D, the three materials could promote the proliferation of MC3T3-E1 cells (P < 0.05), and the composite had the most significant effect in group A (P < 0.05). (3) Compared with the group D, the three materials could promote the alkaline phosphatase activity in MC3T3-E1 cells (P < 0.05), and the group A was the most significant (P < 0.05). (4) Enzyme linked immunosorbent assay showed that the three materials could promote the secretion of osteocalcin and type I collagen in MC3T3-E1 cells, and the promotion effect of group A was the most significant (P < 0.05). (5) RT-PCR showed that the three materials could increase the mRNA expression of RUNX2, OSX, alkaline phosphatase and osteocalcin, especially in group A (P < 0.05). (6) Western blot assay showed that the three materials could increase the protein expression of RUNX2, OSX, alkaline phosphatase and osteocalcin, and the group A had the most significant increase (P < 0.05). (7) The results showed that polymethyl methacrylate/mineralized collagen/Mg-Ca composite could promote the expression of osteogenic differentiation related proteins and genes in MC3T3-E1 cells, and had a positive effect on the osteogenic differentiation.   Figures and Tables | References | Related Articles | Metrics

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Transforming growth factor beta 3 and alginate hydrogel complex on the repair of articular cartilage defects of the knee Liu Yingsong, Guo Xiaopeng, Wei Mingzhu 2022, 26 (16):  2504-2509.  doi: 10.12307/2022.248 Abstract ( 628 )   PDF (983KB) ( 373 )   Save BACKGROUND: Numerous studies have reported that transforming growth factor beta 3 combined with alginate and mesenchymal stem cells can repair cartilage defects in animal experiments. However, there is little research about the effect of transforming growth factor beta 3 and sodium alginate hydrogel combined with mesenchymal stem cells on repairing cartilage injury.  OBJECTIVE: To compare effects of sodium alginate hydrogel and sodium alginate hydrogel loaded with transforming growth factor beta 3 on bone defect with bone marrow mesenchymal stem cells. METHODS: Rabbit bone marrow mesenchymal stem cells were isolated and cultured in vitro. A suitable amount of transforming growth factor beta 3 was added into sodium alginate solution. Before transplantation, bone marrow mesenchymal stem cell suspension was mixed with the hydrogel in equal volumes. Totally 48 New Zealand white rabbits were used to prepare unilateral articular cartilage defects and randomly divided into three groups. The injury group did not take any treatment; the control group was implanted with alginate hydrogel and bone marrow mesenchymal stem cell suspension; and the observation group was implanted with transforming growth factor beta 3-sodium alginate hydrogel complex and bone marrow mesenchymal stem cell suspension. At 12 weeks after operation, the samples were taken for gross and histological observation and type II collagen immunohistochemical staining and RT-PCR.  RESULTS AND CONCLUSION: (1) General observation: At 12 weeks, the defect site of the injury group was filled with a large number of granulation tissue; the control group was filled with translucent cartilage like tissue; and the observation group was filled with new tissue. (2) Histological observation: At 12 weeks after operation, hematoxylin-eosin staining and safranin O staining showed that the defect site in the injury group was filled with more fibrous tissue, and there was a large gap in the central part. In the control group, there were more cartilage like tissue and fibroblast tissue; the surface was irregular; most of the material was degraded; and the material was surrounded by a large number of bone trabeculae. In the observation group, there was a large number of cartilage like tissue, with smooth surface and dense structure, similar to the surrounding normal cartilage tissue. (3) Immunohistochemical staining of type II collagen: only very weak positive staining was found in the injury group, while positive staining was found in the control group and the observation group, and the degree of positive staining in the observation group was significantly stronger than that in the control group. (4) RT-PCR detection: mRNA expression of type II collagen, Sox9 and glycosaminoglycan in the regenerated cartilage of the control group was lower than that of the observation group (P < 0.05). (5) The results suggest that transforming growth factor beta 3-sodium alginate hydrogel complex with bone marrow mesenchymal stem cells can promote the repair of articular cartilage defects and enhance the expression of articular cartilage genes.  Figures and Tables | References | Related Articles | Metrics

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Gelatin collagen composite hydrogel and inducible factor regulate differentiation of rat bone marrow mesenchymal stem cells into hepatocyte-like cells Yuan Yihang, Xu Menghan, Niu Xufeng 2022, 26 (16):  2510-2515.  doi: 10.12307/2022.249 Abstract ( 507 )   PDF (876KB) ( 114 )   Save BACKGROUND: In vitro artificial liver system has become a very effective and practical treatment for liver failure, but there are still some problems such as limited source of cells and limited function of cells. OBJECTIVE: To optimize and screen gelatin collagen composite hydrogel that meet the needs of cell growth, the hydrogel was used as the basal cell growth material to explore the scheme of inducing hepatic differentiation of bone marrow mesenchymal stem cells.  METHODS: Gelatin collagen composite hydrogel with gelatin concentration of 50, 100, 150, 200 g/L was prepared by mixing gelatin solution and collagen solution at different volume ratios (1:1, 2:1, 4:1). The volume ratio of the solution and the gelatin concentration were selected for subsequent experiments by melting point, microstructure, water absorption and porosity. Rat bone marrow mesenchymal stem cells seeded in composite hydrogel were used as experimental group; rat bone marrow mesenchymal stem cells cultured alone were used as controls. Cell proliferation was detected by CCK-8 assay. The two-step induction regimen was used to induce the hepatic differentiation of two groups of rat bone marrow mesenchymal stem cells. The levels of albumin production and urea secretion in the supernatant were tested at 3, 7, 14, and 21 days after induced culture. RESULTS AND CONCLUSION: (1) After testing the melting point, microscopic morphology, water absorption and porosity of the experimental groups with different ratios, the composite gel was most suitable for cell culture when the 150 g/L gelatin solution was mixed with collagen solution at 4:1 volume ratio. (2) CCK-8 assay showed that the proliferation activity of the experimental group was lower than that of the control group at 1, 3 and 5 days, and the difference between the two groups gradually decreased, and there was no difference at 10 days. (3) Experiment of hepatic differentiation showed that with the extension of induction time, the amount of albumin secretion in the two groups increased gradually, and the amount of albumin in the experimental group was higher than that in the control group at 14 and 21 days (P < 0.05). The amount of urea secretion in the two groups increased significantly within 3-7 days of induction, and stabilized after 7 days. The amount of urea secretion in the experimental group was slightly higher than that in the control group at 14 and 21 days, but the difference was not significant (P > 0.05). (4) The results showed that gelatin collagen composite hydrogel could induce rat bone marrow mesenchymal stem cells to differentiate into hepatocyte-like cells. Figures and Tables | References | Related Articles | Metrics

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Effects of co-stimulation of material surface chemistry and fluid shear stress on human umbilical vein endothelial cells Qin Zhongjie, Chen Siqi, Wu Yimin, Yang Jiaojiao, Xia Delin 2022, 26 (16):  2516-2521.  doi: 10.12307/2022.250 Abstract ( 473 )   PDF (1033KB) ( 270 )   Save BACKGROUND: There is a lack of perfect vascular system in tissue-engineered bone, among which vascularization is the key to limit its wide application. Appropriate matrix chemistry and fluid shear stress stimulation can promote the proliferation, differentiation and function of vascular endothelial cells, and guide the design and fabrication of scaffold materials. OBJECTIVE: To explore the effects of different chemical functional groups and fluid shear stress (FSS) on human umbilical vein endothelial cells, in order to find an efficient combination of material chemistry and fluid shear stress on human umbilical vein endothelial cells.  METHODS: Self assembled monolayers with OH, CH3 and NH2 as end functional groups were prepared as matrix materials and blank glass as control. Human umbilical vein endothelial cells were seeded on the surface of four groups of glasses. The release of ATP within 15 minutes after culture and NO within 1 hour after culture was detected. The expression of endothelial nitric oxide synthase protein was detected by western blotting. The formation of focal adhesion and F-actin was observed by laser confocal microscopy. Human umbilical vein endothelial cells were seeded on the surface of four groups of glasses. When the cells fused to 80%, they were loaded with 1.5 N/m2 FSS for 1 hour. ATP release was detected within 15 minutes after loading, and NO release was detected within 1 hour after loading. The expression of endothelial nitric oxide synthase was detected by western blotting after loading for 1 hour. RESULTS AND CONCLUSION: (1) Chemical stimulation had no effect on the release of ATP or NO, but FSS could increase the release of ATP and NO, and the expression of endothelial nitric oxide synthase. When FSS and material chemistry acted simultaneously, the expression of ATP and NO was closely related to material chemistry. The release of ATP and NO and the expression of endothelial nitric oxide synthase were highest in NH2-FSS group, followed by FSS group, and those in the CH3-FSS and OH-FSS groups were lowest. (2) Laser confocal microscope showed that a large number of focal adhesions and cytoskeleton protein F-actin could be detected in the NH2 group, followed by control group; those were least in the CH3 and OH groups. (3) The results showed that the combination of NH2 functional group and FSS produced high-efficiency response to shear stress, and the mechanism may be the formation of optimal focal adhesion and F-actin on NH2 surface.  Figures and Tables | References | Related Articles | Metrics

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Reasons for failure of silica gel and titanium mesh in cranioplasty Zhao Haifeng, Dai Yiping, Zhu Wenyu, Yan Ke, Wang Yu, Wu Jie, Gu Donghua, Xu Xiaofeng, Cao Longxing, Huang Qiang 2022, 26 (16):  2522-2525.  doi: 10.12307/2022.251 Abstract ( 516 )   PDF (728KB) ( 105 )   Save BACKGROUND: Cranioplasty has a long history, but the choice of implant materials has been inconclusive, although constantly updated, ideal implant materials remain unavailable.   OBJECTIVE: To analyze the reasons for the failure of silica gel and titanium mesh for cranioplasty. METHODS:  Five patients with complete long-term follow-up data were selected, including two males and three females, with an average age of 53 years. After cranioplasty, a total of eight operations were performed, including three times of silica gel removal, three times of titanium mesh removal, twice of incision resuture and retaining titanium mesh. The shortest interval duration from cranioplasty was 2 months, and the longest was 20 years. The first symptom was implant exposure or infection. The implant material was mainly silica gel, and the other was incision doubling, and most were titanium mesh. All cases were scanned by CT before and after operation. Combined with clinical symptoms, patients who were considered impossible to be cured without removal of implant materials were surgically removed, and tissues removed by debridement were analyzed by pathology.   RESULTS AND CONCLUSION: (1) Three cases of silicone and titanium mesh implants were removed respectively, besides rejection reaction, incidental folliculitis and external force impact were also contributing factors to the failure of cranioplasty; the latency period of onset was 2 months to 20 years, mainly manifested as infection in the surgical area and exposure of implant materials. (2) In addition to the common leukocyte infiltration, integrin-X subunit (CD11c) and bone morphogenetic protein were also expressed in inflammatory tissues in cases with inflammation on CT imaging. (3) The results show that the sustained rejection reaction lasting for months, years or even decades was the root cause of the failure of silicone and titanium mesh implantation. Occasional scalp folliculitis and external force impact were the triggers. The newly discovered osteogenic reaction on pathological sections remains to be further verified. Figures and Tables | References | Related Articles | Metrics

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Heating palladium-silver alloys under various reduced air pressures and ceramic bond strength Qu Yan, Li Jieyin, Zhuang Xiumei, Ye Jiantao, Ye Xiuhua 2022, 26 (16):  2526-2531.  doi: 10.12307/2022.252 Abstract ( 569 )   PDF (1357KB) ( 172 )   Save BACKGROUND: The effect of heating under different reduced air pressures on the internal oxidation and metal-ceramic bond strength of palladium-silver alloys requires further research, and controversy exists with respect to the bonding mechanism between palladium-silver alloys and porcelain.  OBJECTIVE: To assess the effect of heating under different reduced atmospheric pressure on the metal-ceramic bond strength of palladium-silver alloys.   METHODS: Palladium-silver metallic specimens (25 mm× 3 mm× 0.5 mm) were prepared using a cast method. Specimens were randomly assigned to seven groups, and subjected to heat treatments under six different reduced air pressures of 0.001 8, 0.002 3, 0.003 6, 0.004 6, 0.005 4, and 0.007 1 MPa and under normal atmospheric pressure (0.1 MPa). Scanning electron microscopy and energy-dispersive spectroscopy were used to study the specimens’ microstructure and elemental composition. After treatment, alloys in the seven groups were subjected to a simulated opaque porcelain sintering procedure to analyze the alloying element composition. The palladium-silver alloy-ceramic specimens were prepared and the microscopic morphology of the specimens was observed with scanning electron microscope. The metal-ceramic bond strength was evaluated using a three-point bending test.  RESULTS AND CONCLUSION: (1) Scanning electron microscope displayed that nodules-like protrusions appeared on the surface of the heat-treated alloy. As the oxygen partial pressure increased, the number and volume of nodules on the surface of the alloy increased rapidly. When the oxygen partial pressure increased to 0.007 1 MPa, the nodules on the surface of the alloy were fused and connected into a cord or mesh, and finally almost covered the surface of the alloy, which was similar to the coverage of nodules on the surface of the normal pressure heat treatment alloy. Compared with that before heat treatment, the oxide content on the alloy surface increased significantly after heat treatment. As the oxygen partial pressure increased, the oxide content on the alloy surface showed a decreasing trend. (2) Scanning electron microscopy showed that the microstructure of the metal-porcelain interface was similar in each group. The porcelain was tightly bonded to the alloy. The cord-like structure was visible under the surface of the alloy. As the oxygen partial pressure increased, the cord-like structure increased, and the depth of its penetration into the metal increased. After the simulated opaque porcelain was sintered, the oxide content on the alloy surface continued to decrease. (3) The group with heating under 0.001 8, 0.002 3, and 0.003 6 MPa had significantly higher bond strength than those of heating under 0.004 6, 0.005 4, 0.007 1 MPa, and 0.1 MPa groups (P < 0.05). No statistical differences were observed in the bond strengths between the other groups (P > 0.05). (4) The results show that heating palladium-silver alloys under a lower reduced air pressure (≤ 0.003 6 MPa) effectively improved its bonding strength with porcelain. The internal oxidation and the content of external oxides on the metal surface of palladium-silver alloys were closely related with air pressure in the heat treatment. Figures and Tables | References | Related Articles | Metrics

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Cell-carrying porous methacrylate anhydride gelatin three-dimensional scaffolds and their effects on cell behavior Li Mingxin, Li Jun, Wang Wenchao, Song Ping, Lei Haoyuan, Gui Xingyu, Zhang Chengyun, Zhou Changchun, Liu Lei 2022, 26 (16):  2532-2539.  doi: 10.12307/2022.253 Abstract ( 518 )   PDF (2586KB) ( 200 )   Save BACKGROUND: Hydrogel scaffolds are one of the ideal materials for three-dimensional cell culture. However, the dense network structure in the hydrogel can significantly inhibit the proliferation and extension of cells, and the porous structure in the hydrogel scaffolds can alleviate these problems. OBJECTIVE: To investigate the method of constructing three-dimensional cellular porous hydrogel scaffold with methacrylate anhydride gelatin as scaffold material and polyethylene oxide solution as pore-forming agent, and the effect of porous hydrogel scaffolds on cellular behavior. METHODS: Methacrylate anhydride gelatin hydrogel solution and polyethylene oxide solution were prepared, and mixed in a volume ratio of 4:1, 3:1, 2:1, and 1:1, separately. After adding bone marrow mesenchymal stem cells, a three-dimensional porous hydrogel scaffold that could carry cells were designed and constructed to characterize the microscopic morphology and mechanical properties of the scaffold. The live/dead staining was utilized to observe cell compatibility, and cytoskeleton staining was applied to observe cell morphology. RESULTS AND CONCLUSION: (1) The scanning electron microscope showed that the cross-sections of scaffolds of each group displayed uniformly distributed porous structures, and the pores were connected to each other. The pores were oval-like or round-like. As the proportion of polyethylene oxide solution increased, the pore size of the scaffolds and porosity increased. (2) Multi-frequency strain curves showed that the strain of scaffolds of each group could reach more than 40%, among which the strain of the scaffold with a volume ratio of 1:1 could reach 60%. As the proportion of polyethylene oxide solution increased, the storage modulus of the scaffold decreased, and the mechanical strength of the volume ratio 1:1 scaffold was poor, and it could barely maintain the shape of the scaffold. (3) The live/dead staining of 14 days in vitro culture showed that the survival rate of cells of scaffolds in each group was >85%. (4) Staining of the cytoskeleton cultured for 14 days in vitro showed that most of the cells in the scaffold with a volume ratio of 3:1 were short spindle-shaped, and the cells in the scaffold with a volume ratio of 2:1 and 1:1 were star-shaped or long spindle-shaped. A wide range of connections was established among cells. (5) Three-dimensional cell-carrying porous hydrogel scaffold can significantly promote the spreading and proliferation of bone marrow mesenchymal stem cells. Porous hydrogels with a volume ratio of 2:1 have both mechanical strength and biological properties and can be a good platform for three-dimensional cell culture.  Figures and Tables | References | Related Articles | Metrics

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Three-dimensional finite element analysis of stress distributions in osteoporosis and normal mandibular dental implant-supported overdentures with flat-type and cushion-type magnetic attachments Li Yuan, Song Liang, Zhang Jianguo, Hu Fengling 2022, 26 (16):  2540-2544.  doi: 10.12307/2022.254 Abstract ( 487 )   PDF (742KB) ( 148 )   Save BACKGROUND: Implanting magnetic overdentures use implants, magnetic attachments, and oral mucosa to provide retention, support, and stability for the denture. Therefore, implanting magnetic overdentures are particularly suitable for edentulous patients, especially those with unsatisfactory jaw conditions.  OBJECTIVE: To compare the biomechanical response of normal mandible and osteoporosis mandible in two implants supported with flat-type and cushion-type magnetic attachments.  METHODS: The CT data of mandible and overdenture of one patient with edentulous jaw that met the requirements were selected. A three-dimensional finite element model of a two-implant-retained mandibular overdenture with flat-type and cushion-type magnetic attachments was developed and two types of bone quality (normal and osteoporosis) were prepared. Four types of load were applied to the overdenture in each model: 100 N vertical and oblique (buccal lingual inclination 45°) loads on the right first molar and a 100 N vertical load on the right canine and the lower incisors. The maximum equivalent stresses in cortical bone and cancellous bone of the models were analyzed. RESULTS AND CONCLUSION: (1) Under the same magnetic attachment and loading force, the maximum equivalent stress in normal cortical bone and cancellous bone was greater than in osteoporotic bone. When the lower right first molar was loaded with oblique loading force, the stress value of the cortical bone around the implant was more than twice that of the vertical loading. When the loading conditions were the same, whether it was normal jaw or osteoporotic jaw, the stress value of the flat-type magnetic attachment was higher than that of the cushion-type magnetic attachment. (2) Under the same magnetic attachment and loading force, the maximum stress of the cancellous bone around the normal jaw implant was greater than that of the cancellous bone in the osteoporotic state. When the right lower first molar was inclined to the loading force, the stress value of the cancellous bone around the implant was more than twice that of the vertical load. The maximum stress of the cancellous bone around the normal jaw implant was greater than that of the cancellous bone in the osteoporotic state under the vertical force of the two magnetic attachments. When the loading conditions were the same, whether it was a normal jaw or an osteoporotic jaw, the stress value of the flat-type magnetic attachment was significantly higher than that of the cushion-type magnetic attachment. (3) The results show that in the state of osteoporosis, the low stress on the jaw bone comes from greater elastic deformation of the bone tissue, which is not conducive to osseointegration, and lateral force will cause greater stress around the implant, which is not conducive to the stability of the implant.   Figures and Tables | References | Related Articles | Metrics

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Selection of conditions for fabricated porous scaffolds in bone tissue engineering by silk fibroin protein Yang Xinghua, Zhang Jing, Chen Daiyun, Xiong Shijiang 2022, 26 (16):  2545-2550.  doi: 10.12307/2022.255 Abstract ( 450 )   PDF (2023KB) ( 116 )   Save BACKGROUND: The pore-forming technology of silk fibroin scaffolds is mostly prepared by freezing or freeze-drying methods, but different concentrations and temperatures have an impact on the physical and biological properties of the scaffold. There is no clear study on which freezing method or concentration is used for the preparation of the bone tissue scaffold.   OBJECTIVE: To study the effects of concentration, freezing condition and 10 g/L polyethylene glycol on the properties of silk fibroin scaffolds under the condition of pore-induced water, and to select the suitable production conditions for the fabrication of bone tissue engineering scaffolds. METHODS: The silk fibroin protein solutions of 30, 60, 90 g/L were prepared. After pre-frozen at -20 ℃, the silk fibroin solution of each mass concentration was divided into four groups to prepare porous scaffolds: -20 ℃ freezing treatment group, -60 ℃ freezing treatment group, -20 ℃ lyophilization treatment group, and -60 ℃ lyophilization treatment group. The pore size, hydrophilicity, porosity and compression strength of the scaffolds and cell compatibility were determined in each group. The surface morphology of the material was observed by scanning electron microscope. Based on the above results, the optimal freezing conditions and the mass concentration of silk fibroin solution for preparing porous scaffolds were obtained. Polyethylene glycol and 60 g/L silk fibroin solution were mixed uniformly, and lyophilized method at -60 ℃ was used to prepare silk fibroin porous scaffolds. The compressive strength, tensile strength and cell compatibility of the composite scaffold were tested.   RESULTS AND CONCLUSION: (1) The pore size, porosity, hydrophilicity, compressive strength and cell compatibility results showed that 60 g/L silk fibroin solution was pre-frozen at -20℃ and then lyophilized at -60 ℃ to obtain the best porous scaffold. The scaffold had a pore size of (213.07±37.89) µm and a porosity rate of 85%, which could promote the proliferation of bone marrow mesenchymal stem cells. (2) The addition of polyethylene glycol could increase the compressive and tensile strength of the silk fibroin scaffold (P < 0.05). (3) Bone marrow mesenchymal stem cells were seeded on a polyethylene glycol-silk fibroin composite scaffold. Scanning electron microscopy for 7 days of co-cultivation showed that the cells adhered to the scaffold sufficiently and the synapses on the cell surface were fully stretched. Hematoxylin-eosin staining at 2 weeks of co-cultivation showed that the cells adhered to the stent wall and the nuclei were deeply stained. At 4 weeks, the cells adhered tightly in the channel of the stent hole, filled the entire channel, and proliferated faster. Immunohistochemical staining for 2 weeks of co-culture showed that type I collagen, RUNX2, and osteocalcin were negatively expressed. RT-PCR detection of co-culture for 3 weeks showed that the composite scaffold had no effect on the differentiation of bone marrow mesenchymal stem cells. (4) It is concluded that at -60℃, 60 g/L silk fibroin freeze-dried porous scaffold is suitable for bone tissue engineering. 10 g/L polyethylene glycol can increase the tensile and compressive strength of the material. Silk fibroin scaffold has no induction effect on cell differentiation. Figures and Tables | References | Related Articles | Metrics

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Topical application of mycophenolate mofetil prevents epidural fibrosis by inhibiting the proliferation and migration of fibroblasts Zhu Dongming, Zhang Zhen, Zhang Jie, Yan Lianqi 2022, 26 (16):  2551-2556.  doi: 10.12307/2022.256 Abstract ( 502 )   PDF (980KB) ( 224 )   Save BACKGROUND: Studies have shown that epidural fibrosis after laminectomy is mainly caused by the proliferation and migration of fibroblasts, and mycophenolate mofetil can inhibit the proliferation and migration of fibroblasts.   OBJECTIVE: To explore the effect of topical application of mycophenolate mofetil in preventing epidural fibrosis after laminectomy and its possible mechanism. METHODS:  (1) Cell test: Fibroblasts were separately treated with 0, 0.01, 0.1, 1, 10, and 100 μmol/L mycophenolate mofetil solution for 24 hours. Cell viability was detected by CCK-8 assay, and the appropriate treatment concentration was selected for subsequent cell experiments. Fibroblasts were separately treated with 0, 0.1, 1, 10 μmol/L mycophenolate mofetil solution for 24 hours. EdU assay and cell cycle assay were used to detect cell proliferation. Wound scratch assay and transwell assay were used to detect cell migration. Western blot assay was used to detect the expression of cell proliferation-related proteins (nuclear proliferation antigen, Cyclin D1) and migration-related proteins (α-tubulin, vinculin). (2) Animal test: Forty-eight adult SD rats were selected to construct rat laminectomy model and randomly divided into four groups. In the control group, cotton pads soaked with normal saline were placed on the postoperative bone defect area. In the low, medium, and high concentration groups, cotton pads soaked with 2.5, 5, and 10 g/L mycophenolate mofetil solution were placed on the postoperative bone defect area. Four weeks after the operation, the vertebral body of the operative area was taken for histological analysis.   RESULTS AND CONCLUSION: (1) Cell test results: CCK-8 assay showed that mycophenolate mofetil inhibited the viability of fibroblasts in a concentration-dependent manner. EdU assay showed that mycophenolate mofetil inhibited the proliferation of fibroblasts in a concentration-dependent manner. Flow cytometry showed that 0.1 μmol/L mycophenolate mofetil solution blocked the cell cycle in G0/G1 phase. Wound scratch assay and transwell assay showed that mycophenolate mofetil inhibited the migration of fibroblasts in a concentration-dependent manner. Western blot assay showed that mycophenolate mofetil inhibited the expression of fibroblast proliferation-related protein and migration-related protein in a concentration-dependent manner. (2) Animal test results: Histological observation showed that with the increase of mycophenolate mofetil concentration, the number of fibroblasts and collagen production in the fibrotic tissue of the surgical area gradually decreased. (3) The results showed that the topical application of mycophenolate mofetil after laminectomy can effectively prevent the occurrence of epidural fibrosis, possibly by inhibiting the proliferation and migration of fibroblasts. Figures and Tables | References | Related Articles | Metrics

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Evaluation on the preparation and performance of lysine modified polylactic acid nanofiber stent Li Yu, Pan Yuancheng, Lin Ran, Chen Shunyou 2022, 26 (16):  2557-2561.  doi: 10.12307/2022.257 Abstract ( 645 )   PDF (958KB) ( 164 )   Save BACKGROUND: Polylactic acid as a biodegradable polymer has been made into nanofiber stent, widely used in tissue regeneration. However, as a scaffold material, polylactic acid has some limitations, such as slow degradation rate and poor biocompatibility.  OBJECTIVE: To prepare lysine-polylactic acid stents to study the structure and properties of stents by controlling different lysine concentrations.   METHODS: With 1, 4-dioxane as solvent system and lysine as an ammonia solution, thermally induced phase separation technology was used to prepare the lysine-polylactic acid stents. Lysine concentrations were 5%, 10%, 15%, 30%, respectively. The detection of Fourier transform infrared spectrometer, scanning electron microscope, differential scanner thermal analyzer, contact angle and mechanical performance analysis were carried out with the unaltered polylactic acid bracket as the control.  RESULTS AND CONCLUSION: (1) Fourier transform infrared spectral analysis showed that the polylactic acid stent was successfully modified by lysine ammonia. (2) The scanning electron microscope showed that when the non-solvent phase was deuterium depleted water, the fiber mesh structure of the bracket was poor and no three-dimensional structure was formed. When the concentration of lysine was 5%, the stent was flaky, ribbon or a large number of reunion phenomenon, and no good three-dimensional fiber network structure was formed. With the increase of lysine concentration, the nanofiber structure of the stent gradually formed. When the concentration of lysine was 10%, the prepared stent still had flaky and reunion phenomenon. When the concentration of lysine was 15%, the stent had a relatively uniform distribution of nanofiber structure. However, when the concentration of lysine was 30%, the structure of stent fiber collapsed and large areas reunited. (3) With the increase of lysine concentration, the water contact angle of the stent was reduced and the strength of pressure was reduced. (4) With the increase of lysine concentration, the melting temperature of the stent decreased slightly, but there was no obvious change, and the crystallization increased. (5) The results show that the introduction of lysine improves the mesh fiber structure, hydrophobicity and crystallization of polylactic acid stent and reduces the mechanical properties of the bracket.  Figures and Tables | References | Related Articles | Metrics

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Surface treatment of iron oxide nanoparticles in bone defect repair Ma Ziyu, Zhang Yuntao, Ma Xiangrui, Qiao Luhui, Guo Haoyu, Hou Yudong 2022, 26 (16):  2570-2575.  doi: 10.12307/2022.259 Abstract ( 578 )   PDF (716KB) ( 1354 )   Save BACKGROUND: With the progress and development of nanotechnology, nano-particles have attracted extensive attention due to their nanomaterial properties, among which ferric oxide nanoparticles can be used in electronics, chemistry, biomedicine and other fields. OBJECTIVE: To discuss the progress of surface treatment of iron oxide nanoparticles in bone defect repair. METHODS: A computer-based search of PubMed, Wanfang, CNKI, and VIP database was performed for retrieving articles published from 2005 to 2020, and the Chinese search terms were “magnetic nanoparticles, iron oxide nanoparticles, surface modification, surface treatment, surface modification, bone defect, bone repair, bone regeneration”. The English search terms were “IONPS, iron oxide nanoparticles, surface treatment, surface modification, bone repair, bone regeneration, osteogenesis”.  RESULTS AND CONCLUSION: In recent years, iron oxide nanoparticles have been increasingly studied in the medical field, from the initial magnetic resonance imaging, to later drug delivery, stem cell therapy, tissue repair and hyperthermia. For different research purposes, the emphasis of iron oxide nanoparticles is also slightly different, which requires different surface treatments of nanoparticles. For bone defect repair, materials for surface treatment of iron oxide nanoparticles  mainly include organic and inorganic materials. Some breakthroughs have been made, but how to control the size of the nanoparticles, increase its stability, and under the additional magnetic field environment, biology mechanism between nanoparticles and cells still need further exploration. Figures and Tables | References | Related Articles | Metrics

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Effects of biochemical modification of titanium implant surface on the osseointegration Che Zhenjia, Zhu Zhengqing, Zhu Liwei, Li Youbin, Zhu Chenyi, Huang Lanfeng 2022, 26 (16):  2576-2583.  doi: 10.12307/2022.260 Abstract ( 770 )   PDF (726KB) ( 334 )   Save BACKGROUND: Titanium and titanium alloys are widely used in the field of orthopedic implantation, because of their good mechanical properties and biological inertia. OBJECTIVE: To review the effects of different biomolecules on titanium implant surface on osseointegration. METHODS: PubMed, Web of Science, VIP, Wanfang, and CNKI were searched using “titanium, osseointegration, biochemical modification, coating” as keywords in Chinese and English for relevant articles published from 1991 to 2020. Finally, 104 articles were included in result analysis after screening and summarizing. RESULTS AND CONCLUSION: The single physical and chemical modification of titanium surface is mainly affecting the cell behavior indirectly, and the biomolecular coatings can be directly involved in the biological process, which is more effective in bone formation, not only greatly improves the early osseointegration between bone and the implants, but also reduces the incidence of surgical failure and prosthesis revision due to inflammatory reaction. Although the biochemical modification of titanium implants can be directly involved in the biological process, there are still plenty of problems that need to be solved: the long-term stability, releasing rate, and mechanism between the implants and cells and tissues need to be further studied to achieve early and long-term osseointegration between bone and the implants. Figures and Tables | References | Related Articles | Metrics

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Application of inorganic nonmetallic artificial bone materials in vivo Wei Zhangao, Xu Linghan, Wu Zichen, Tang Hao, Chen Jialong 2022, 26 (16):  2584-2589.  doi: 10.12307/2022.261 Abstract ( 750 )   PDF (678KB) ( 1890 )   Save BACKGROUND: The source of autologous bone is limited, and there are the risk of disease transmission and immune rejection of allogeneic bone. As a result, artificial bone is used more and more widely in the treatment of bone defects. Inorganic nonmetal artificial bone has been paid more attention due to its good biological activity.  OBJECTIVE: To review the research progress of inorganic nonmetallic artificial bone in vivo to repair bone defects in recent years, and look forward to the development direction of this kind of materials. METHODS: The first author used computer to search articles on bone repair materials in PubMed (2015-2020), CNKI (2013-2020). The keywords were “bone repair materials, bioactive ceramics, bone cement, bone defect, artificial bone” in Chinese and English. Totally 5 420 articles were retrieved, and the articles related to the bioactive ceramics and bone cement were eventually included. According to the inclusion and exclusion criteria, 46 articles were reviewed.  RESULTS AND CONCLUSION: At present, inorganic nonmetallic artificial bone materials include bioactive ceramics and bone cement with good osteoconductivity, osteoinductivity and biological activity. However, these materials have poor mechanical properties and poor biodegradability when used alone. By mixing different bioactive materials to simulate natural bone components, exploring processing techniques to optimize the material microstructure, and modifying the surface to improve osteogenic activity, composite artificial bones with better mechanical properties, better degradation rates, and excellent biocompatibility can be prepared. The characteristics of different parts of the bone are quite different, and the performance requirements of the materials are different, so a large number of in vivo studies are still needed to evaluate the effect of composite artificial bone on the treatment of different parts of bone defects.  Figures and Tables | References | Related Articles | Metrics

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Application of self-healing hydrogels in bone tissue engineering Fu Zheng, Li Runze, Luo Haotian, Chen Jun, Wang Weicai 2022, 26 (16):  2590-2595.  doi: 10.12307/2022.262 Abstract ( 876 )   PDF (709KB) ( 2842 )   Save BACKGROUND: Self-healing hydrogels are scaffold materials with superior self-healing capability and biocompatibility, and are widely used in bone tissue engineering. OBJECTIVE: To introduce the gelatin mechanism and composition of self-healing hydrogels and summarize their applications in bone tissue engineering. METHODS: The first author searched both Chinese and English articles with key words “self-healing hydrogels; bone tissue engineering; bone regeneration” on CNKI, Wanfang, VIP, PubMed, Embase and Web of Science databases published from 2000 to 2020. Totally 69 eligible articles were selected for review. RESULTS AND CONCLUSION: The gelation mechanisms of self-healing hydrogels include dynamic covalent bonds, supramolecular bonds and multi-mechanism cross-links. Self-healing hydrogels can be composed of natural polymers, synthetic polymers and nanocomposites. Self-healing hydrogels have been found to be applied in bone tissue engineering through scaffold modification as stem cells delivery vehicle. The application of self-healing hydrogels in bone tissue engineering can be broaden by enhancing the mechanical properties of the hydrogel while maintaining its self-healing capability. Additionally, the specific mechanism for better superiority of self-repairing hydrogels over traditional hydrogels in bone tissue engineering is still unclear. Figures and Tables | References | Related Articles | Metrics

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Topical simvastatin administration in the treatment of periodontitis: effect of loading on sustained drug release system or biomaterial scaffold system Liu Xiaolin, Liu Shutai, Han Xiaoqian, Mu Xinyue 2022, 26 (16):  2596-2601.  doi: 10.12307/2022.263 Abstract ( 912 )   PDF (671KB) ( 835 )   Save BACKGROUND: Traditional periodontal therapy cannot restore periodontal soft and hard tissue. It is hoped to explore the effect of local simvastatin administration system on periodontitis, and open up a new way for clinical treatment of periodontitis.   OBJECTIVE: To review the mechanisms of simvastatin on promoting periodontal bone regeneration and on treating periodontitis, as well as the advantages, disadvantages and preparation methods of local simvastatin drug delivery system, biomaterial scaffold system and local gel drug delivery system.  METHODS: The first author retrieved the articles published from 1988 to 2020 in PubMed, Wanfang, CNKI and other literature databases. The English key words were “simvastatin; microspheres; hydrogels; periodontitis; bone tissue engineering”. The Chinese key words were “simvastatin; sustained drug release; biomaterial scaffold; gel system; periodontitis; bone tissue engineering”. A total of 50 articles that met the criteria were included for review.  RESULTS AND CONCLUSION: With the development of tissue engineering, experimental and clinical studies have mixed growth factors, scaffold materials and carriers to prepare copolymer with more biocompatibility, fluidity and promotion of bone regeneration, which is used to assist the treatment of periodontitis and has achieved good results. In recent years of research, some scholars loaded simvastatin on sustained release system; some scholars loaded simvastatin on biomaterial stent system; some scholars loaded simvastatin on the gel drug delivery system. All these methods have good slow-release drug effect, and promote the periodontal bone regeneration. Figures and Tables | References | Related Articles | Metrics

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Preparation and biological properties of zinc-doped hydroxyapatite Tang Yanan, Gao Teng, Ren Guiyun 2022, 26 (16):  2602-2607.  doi: 10.12307/2022.264 Abstract ( 797 )   PDF (638KB) ( 152 )   Save BACKGROUND: With the development of bone tissue regeneration engineering research, artificial biomaterials are widely used in bone defect repair. How to modify biomaterials to make them have better mechanical and biological properties to meet the clinical application of bone defect repair has always been the focus of biomaterials research. OBJECTIVE: To review the research progress of zinc-doped hydroxyapatite in recent years, in order to provide more references for future scientific research and clinical application. METHODS: The search terms “zinc, hydroxyapatite, zinc-doped hydroxyapatite, in vivo, in vitro, bacteriostasis, bone defect” in English and Chinese were used to retrieve articles on zinc-doped hydroxyapatite published from 2000 to 2020 on CNKI, PubMed and FMRS using computer.  RESULTS AND CONCLUSION: There are many preparation methods of zinc-doped hydroxyapatite, among which chemical precipitation method, hydrothermal synthesis method and sol-gel method are widely used. The crystal structure of hydroxyapatite does not change with the addition of zinc, but with the increase of zinc concentration, the crystal nucleus size and crystallinity gradually decrease. A small amount of zinc doping can significantly improve the biocompatibility, biological activity and antibacterial activity of hydroxyapatite, while a large amount of zinc doping can cause toxic reaction. Therefore, we should choose the appropriate preparation method and strictly control the reaction conditions in the practical research and application to prepare zinc-doped hydroxyapatite composite materials that meet the needs of clinical bone defect repair. Figures and Tables | References | Related Articles | Metrics

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Improvement and new development of hollow fiber membrane materials for membrane artificial lung Li Yakun, Hei Feilong 2022, 26 (16):  2608-2612.  doi: 10.12307/2022.265 Abstract ( 809 )   PDF (652KB) ( 540 )   Save BACKGROUND: With the emergence of various high-quality membrane materials, the selection of suitable membrane materials has become the key to the development of artificial lung technology. The surface modification of membrane materials by physical or chemical methods to prepare composite membranes with excellent performance such as good blood compatibility and high gas exchange rate is a hot topic in current research. OBJECTIVE: Based on the development process of artificial lung, the commonly used membrane materials were introduced, and the research results of improving the blood compatibility of membrane materials were reviewed, and the new direction of improving the hollow fiber membrane materials for artificial lung in the future was proposed. METHODS: The articles related to artificial lung membrane materials published on PubMed database, CNKI database and Wanfang database were searched, and the articles were read and screened. Key words in English and Chinese were “artificial lung; membrane artificial lung; oxygenator; hollow fiber membrane; polymer; blood compatibility”. RESULTS AND CONCLUSION: In recent years, various kinds of molecules that can improve blood compatibility have been used by researchers to improve the surface of membrane materials of membrane artificial lung. Studies on modified membrane materials such as heparin, hydrophilic molecules (such as polyethylene glycol) and amphoteric molecules (such as phosphocholine) are relatively mature and have been widely used in clinical practice. Other improvement measures (such as surface endothelialization, NO release hollow fiber) are also gradually developed. However, there are few studies on improving the gas exchange capacity of membrane materials, and there is still room for further improvement and optimization in oxygenation performance. In the future, the research of artificial lung membrane materials will develop in two directions: one is to develop the surface modified coating of mixed membrane materials to maximize blood compatibility by combining the advantages of various materials. Second, the gas exchange oxygenation performance of membrane materials can be improved and plasma leakage can be avoided by improving hemodynamics, improving membrane making process, physical or chemical modification and other methods. Figures and Tables | References | Related Articles | Metrics

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Long-circulating lipsomes: application and mechanism Cai Xiaoxuan, Lü Yingnian, Qi Yi 2022, 26 (16):  2613-2617.  doi: 10.12307/2022.266 Abstract ( 976 )   PDF (710KB) ( 3293 )   Save BACKGROUND: At present, liposomes have been used as drug carriers, in which long-circulating liposomes can further improve the bioavailability of drugs.  OBJECTIVE: To summarize the research status and development trend of long-circulating liposomes at home and abroad from the aspects of classification, application fields and action mechanism. METHODS: Wanfang, CNKI, PubMed and Web of Science were searched by entering keywords “liposomes long-circulating, hypertension, peptides” in Chinese and “PEG, antihypertensive, long-circulating liposomes, diabetes, tumour, virus, peptide” in English. Through reading the title and abstract for preliminary screening, the articles with low relevance to the topic were excluded. Finally, 57 articles were included for the result analysis. RESULTS AND CONCLUSION: (1) Long-circulating liposomes are not easily absorbed by mononuclear phagocyte system and can prolong the circulation time of drugs in vivo, so they play an important role in anti-hypertension, anti-tumor, anti-diabetes, anti-virus and other diseases. (2) Significant progress has been made in the development of various materials for surface modification of liposomes, such as polyethylene glycol. (3) The latest preparation methods of liposomes, such as microfluidic technology, supercritical fluid method and ethanol injection method, make up for the shortcomings of traditional preparation methods. Figures and Tables | References | Related Articles | Metrics

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Application and existing problems of polyethylene glycol in the field of neurological reconstruction Wei Jingjing, Li Chenyang, Wang Ping, Li Yaxuan, Ding Xiaofang, Yang Lin 2022, 26 (16):  2618-2624.  doi: 10.12307/2022.267 Abstract ( 665 )   PDF (757KB) ( 200 )   Save BACKGROUND: Autologous nerve transplantation is widely used clinically to achieve the purpose of nerve repair, but the application effect is not good. The application of polyethylene glycol ranges from cell fusion agents to hydrogel bioadhesives to new materials for promoting axon fusion nerve repair. Therefore, if it can be combined with polyethylene glycol to explore ways to speed up the reconstruction of nerve function, it can be better applied to the clinic, and it will also have important significance for nerve regeneration and functional reconstruction. OBJECTIVE: To describe the application and progress of polyethylene glycol in the field of neurological reconstruction. METHODS: PubMed and CNKI were used to retrieve articles about polyethylene glycol promoting cell fusion and polyethylene glycol acting on nerve repair. The search time was from October 2020 to March 2021. The English search terms were “PEG, polyethylene glycol, cell-fusion, nerve function reconstruction, nerve repair”. The Chinese search terms were “polyethylene glycol, cell fusion, function reconstruction, nerve repair”. All articles were initially screened according to the inclusion and exclusion criteria, and 61 articles with higher relevance were retained for review.  RESULTS AND CONCLUSION: (1) Under certain conditions, 70% polyethylene glycol was added with a small amount of adenosine 5’-triphosphate, which can accelerate the rapid growth of injured nerve axons, effectively promote membrane fusion, and realize the reconstruction of nerve cell structure and function. (2) The main factor affecting the efficiency of cell fusion is the concentration of polyethylene glycol itself. When its concentration is 35%, the relative molecular mass is 4 000, or when the concentration is 50%, the relative molecular mass is 1 000, greatest impact on cell fusion efficiency is found. The other minor influencing factors are the number of fused cells, the reaction temperature, and time. (3) In further research on different mechanisms of promoting nerve repair, polyethylene glycol can promote axon fusion, which is manifested in the restoration of the continuity of axon morphology and its electrophysiological function. However, further research is needed to prove whether the effective connection of axons can be realized before Wallerian degeneration. (4) Polyethylene glycol has a broad application prospect. In the future, it can be considered in the research and development of new bioadhesives, nerve repair stent improvement, and composite hydrogel research. However, the application of polyethylene glycol in the field of nerve function reconstruction still has many unresolved problems, such as the long-term effects of polyethylene glycol-induced neuronal fusion on the human body, and the maximum delay in treatment time, which need to be continuously improved by follow-up research.  Figures and Tables | References | Related Articles | Metrics

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A network meta-analysis of the efficacy of new medical dressings for diabetic foot ulcers Zhou Junli, Wang Xiaojun, Wang Haijiao, Li Chun 2022, 26 (16):  2562-2569.  doi: 10.12307/2022.258 Abstract ( 693 )   PDF (1055KB) ( 354 )   Save OBJECTIVE: In recent years, a variety of new medical dressings have been used in the treatment of diabetic foot ulcer, and it is not clear which dressing has the best effect. Therefore, this study used network meta-analysis technology to systematically evaluate the efficacy of different new medical dressings in the treatment of diabetic foot ulcer. METHODS: A computer search was conducted on CNKI, Wanfang Data Knowledge Service Platform, VIP, China Biomedical Literature Database, PubMed, EMbase, Cochrane Library, and Web of Science databases from the database establishment to November 2020. Randomized controlled trials of new medical dressings in the treatment of diabetic foot ulcer were included. The bias risk assessment tool of the Cochrane systematic evaluation was used to evaluate the quality of the included literature. Two researchers screened the literature and extracted relevant data. RevMan 5.3, ADDIS 1.16.6 and Stata 14.0 software were used for literature quality evaluation and data analysis. RESULTS: A total of 33 randomized controlled trials involving 2 520 patients with diabetic foot ulcers were included, 10 of which were low-risk bias, 19 of which were medium-risk bias, and 4 of which were high-risk bias. Network meta-analysis results showed that (1) regarding the cure rate, the silver ion dressings, epidermal growth factor, platelet rich plasma, and amniotic membrane were superior to traditional dressings and alginate dressings; platelet rich plasma was better than that of the silver ion dressings; honey dressing was better than traditional dressings (P < 0.05). A probability results show that the top three dressings was platelet rich plasma, amniotic membrane, and epidermal growth factor. (2) In terms of healing time, silver ion dressings, epidermal growth factor and platelet rich plasma were all better than traditional dressings and alginate dressings, and honey dressings were all better than alginate dressings (P < 0.05). The probability results showed that epidermal growth factor, platelet rich plasma and silver ion dressings ranked the third.  CONCLUSION: (1) Based on the results of 33 randomized controlled trials confirm that in many new medical dressings, platelet-rich plasma, epidermal growth factor, amniotic membrane, and silver ion dressings are superior to other dressings in the treatment of diabetic foot ulcer. In the cure rate of diabetic foot, the best dressing was platelet-rich plasma. In terms of healing time of diabetic foot ulcers, epidermal growth factor ranked best.  Figures and Tables | References | Related Articles | Metrics