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28 July 2023, Volume 27 Issue 21 Previous Issue    Next Issue

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Finite element analysis of proximal femoral nail anti-rotation for treating unstable femoral intertrochanteric fracture under different bones with bone cement augmentation Guo Hao, Chen Guangxin, Chen Xiaoqin, Lian Hongyu, Liu Xinwei, Li Zitao 2023, 27 (21):  3281-3286.  doi: 10.12307/2023.465 Abstract ( 122 )   PDF (1296KB) ( 22 )   Save BACKGROUND: For type A3.3 intertrochanteric fractures, proximal femoral nail anti-rotation is the most commonly used treatment. The stability of the fracture end after common proximal femoral nail anti-rotation surgery is not well, and bone cement can play a good stabilizing role.   OBJECTIVE: To simulate the biomechanical effects of bone cement on the treatment of unstable intertrochanteric fractures with different degrees of osteoporosis after proximal femoral nail anti-rotation using the finite element method.  METHODS: A finite element model of a normal right femur was created from CT images using related finite element analysis software. The femur was divided into the proximal femoral bone, lesser trochanter, and femoral body in SolidWorks 2017 software according to the AO31-A3.3 classification. Totally 12 types of fracture models with different degrees of osteoporosis fixed using proximal femoral nail anti-rotation were established in the experimental group. In the control group, 12 types of osteoporotic fracture models were fixed using bone cement augmented proximal femoral nail anti-rotation. The differences in the maximum displacement of the femur, proximal femoral nail anti-rotation, femoral stress, and varus angle between the two groups were observed in ANSYS software.  RESULTS AND CONCLUSION: (1) Under the same bone condition, the displacement of the femoral head, the displacement of the proximal femoral nail anti-rotation and the varus angle of the femoral neck in the control group were lower than those in the experimental group, and the maximum femoral stress value was higher in the control group than that in the experimental group. (2) The change rate of femoral head displacement, proximal femoral nail anti-rotation displacement, and varus angle decreased from 2.94% to 5.89%, 3.23% to 4.79%, and 0.41% to 8.51% with increase in the degree of femur osteoporosis. The maximum stress change rate of the femur increased from 12.2% to 5.74%. (3) These results suggest that in dealing with A3.3 femoral intertrochanteric fractures with different degrees of osteoporosis, cement augmented proximal femoral nail anti-rotation had better mechanical stability than ordinary proximal femoral nail anti-rotation, and the effect was most significant in severe osteoporosis. Moreover, the experimental analysis of bone cement augmented proximal femoral nail anti-rotation is not suitable for normal bone and mild bone loss.  Figures and Tables | References | Related Articles | Metrics

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Biomechanical characteristics of bone cement augmentation internal fixation system in patients with osteoporosis Nie Wenzhong, Jiang Guangpu, Han Xiao, Xu Wei 2023, 27 (21):  3287-3292.  doi: 10.12307/2023.456 Abstract ( 121 )   PDF (1296KB) ( 12 )   Save BACKGROUND: In patients undergoing interbody fusion surgery, the proportion of patients with osteoporosis is increasing. Osteoporosis has an impact on the fixation effect of screw rod system, such as extraction of pedicle screw, failure of interbody fusion surgery, and so on. The use of bone cement screw channel augmentation surgery has effectively improved this problem. OBJECTIVE: To compare biomechanical changes of lumbar spine strengthened with different bone cement nail channels under the condition of low bone mineral density by finite element method.  METHODS: A finite element model of L4-5 vertebral body functional unit was established according to the extracted CT images. All vertebral body bone materials were set as osteoporotic state. Models of non-cemented screw channel augmentation, all-bone cement screw channel augmentation, L4 vertebral body bone cement screw channel augmentation, unilateral bone cement screw channel augmentation, and cross bone cement screw channel augmentation were established. The lower surface of the L5 segment was fixed. The upper surface of the L4 segment was subjected to a vertical downward load of 500 N and a moment of 7.5 N•m. The von-Mises stresses of the screw rod system, vertebral body screw channel and bone cement mass were detected.  RESULTS AND CONCLUSION: (1) Compared with the non-cemented screw channel fixation group, the effect of the bone cement augmentation groups on the von-Mises stress of the screw-rod system was very small. (2) The von-Mises stress of the bone-cemented screw channel in each group was generally smaller than that of the non-cemented screw channel group; the more significant one was the all-bone cement screw channel augmentation group. All-bone cement screw channel augmentation group had a similar effect to the cross bone cement augmentation group. The decrease of von-Mises stress in the unilateral bone cement screw channel augmentation group was lower than that of the cross bone cement augmentation group. The L4 vertebral bone cement screw channel augmentation group had no obvious effect on the reduction of the screw channel von-Mises stress, and the screw channel von-Mises stress was higher than that of the non-cemented screw channel fixation group during scoliosis and rotation. (3) Under various motion states, the von-Mises stress of bone cement in all-bone cement screw channel augmentation group was the minimum value. The von-Mises stress of bone cement in the unilateral bone cement screw channel augmentation group and the cross bone cement screw channel augmentation group was slightly greater than that of the all-bone cement screw channel augmentation group. (4) These results showed that the bone cement screw channel augmentation technology effectively reduces the stress concentration effect of the screw rod fixation system on the vertebral screw channel, optimizes the stress distribution of the internal fixation system, and reduces the risk of screw loosening relative to the vertebral body. The effects of different bone cement screw channel augmentation methods are different, but the overall trend is the reduction of screw channel stress. Among them, the most effective fixation methods are all-bone cement screw channel augmentation and cross bone cement screw channel augmentation.   Figures and Tables | References | Related Articles | Metrics

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Mechanical stimulation enhances matrix formation of three-dimensional bioprinted cartilage constructs Sun Kexin, Zeng Jinshi, Li Jia, Jiang Haiyue, Liu Xia 2023, 27 (21):  3293-3299.  doi: 10.12307/2023.162 Abstract ( 120 )   PDF (2414KB) ( 7 )   Save BACKGROUND: Uneven secretion of matrix and insufficient mechanical strength are important factors affecting the formation effect of tissue engineering constructs in vivo. Mechanical stimulation is an effective means to promote the secretion of extracellular matrix. OBJECTIVE: To explore the biological performance of 3D bioprinted composite scaffolds under mechanical stimulation. METHODS: The chondrocyte-gelatin methacryloyl composite scaffold was prepared and printed by 3D bioprinting technology. Cell survival was observed by live/dead cell staining. The composite scaffolds were placed in a mechanical pressurized bioreactor for pressurized culture. The composite scaffolds cultured in a 6-well plate without pressurization were used as the control. Live/dead cell staining was used to observe the cell survival. Histological staining was used to observe the in vitro cartilage of the composite scaffolds. The relative expression levels of cartilage-related genes were detected by real-time quantitative PCR. The composite scaffolds were implanted into nude mice for 5 weeks in vitro with or without mechanical stimulation, and the cartilage formation was observed by histological staining. RESULTS AND CONCLUSION: (1) The appearance of the composite scaffolds showed a clear grid-like structure. When cultured for 1, 4, and 7 days in vitro, the scaffolds had stable morphology and clear structure, and the cell viability was above 90%. (2) After 2 weeks of culture, the cell survival rate in the composite scaffold in the pressurized group was lower than that in the unpressurized group (P < 0.05). Hematoxylin-eosin staining exhibited that composite scaffolds of the two groups had obvious cartilage lacuna structure, and the cells were distributed evenly in the materials. In the pressurized group, more new cartilage tissue was formed in the gap of the composite scaffold. Safranin O staining showed that red cartilage matrix was formed in both groups; the stained pericellular matrix was deeper in the pressurized group. Type I collagen immunohistochemical staining showed that the coloration in the pressurized group was more obvious; the mRNA expression levels of elastin and type II collagen in the pressurized group were higher than those in the unpressurized group (P < 0.05). (3) After 5 weeks of subcutaneous implantation in nude mice, hematoxylin-eosin staining showed that the formation of cartilage tissue in the pressurized group was more uniform; the size of chondrocytes was uniform; the lacuna structure was obvious. (4) The results show that although in vitro stimulation can trigger cell death in the 3D bioprinted chondrocyte-gelatin methacryloyl composite scaffold, it also promotes the ingrowth of surviving cells into the space of the scaffold and increases the expression of their cartilage matrix-related genes, to promote cartilage formation.  Figures and Tables | References | Related Articles | Metrics

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Promoting angiogenesis of platelet-derived growth factor BB modified polycaprolactone and beta-tricalcium phosphate composite scaffolds Zhao Jinlong, Liu Jichao, Yu Yang 2023, 27 (21):  3300-3306.  doi: 10.12307/2023.415 Abstract ( 146 )   PDF (1239KB) ( 6 )   Save BACKGROUND: The development of tissue engineering technology provides new ideas for the repair and reconstruction of bone defects, but the problem of vascularization restricts the clinical application of tissue engineered bone. Platelet-derived growth factor can promote the formation of blood vessels in bone tissue while promoting the formation of bone cells.  OBJECTIVE: To observe the effects of polycaprolactone /β-tricalcium phosphate/platelet-derived growth factor BB (PCL/β-TCP/PDGF BB) scaffold on osteogenic differentiation of bone marrow mesenchymal stem cells and proliferation and adhesion of human umbilical vein endothelial cells in vitro, as well as the effect of its application in animal bone defects. METHODS: (1) Polycaprolactone/β-tricalcium phosphate scaffolds were prepared by 3D rapid prototyping machine, and the scaffolds were immersed in platelet-derived growth factor BB solution to prepare PCL/β-TCP/PDGF BB scaffold. (2) In vitro experiment: Bone marrow mesenchymal stem cells and human umbilical vein endothelial cells were inoculated on two kinds of scaffolds, respectively, to detect the osteogenic differentiation of bone marrow mesenchymal stem cells, and to detect the proliferation, adhesion and angiogenic gene expression of human umbilical vein endothelial cells. (3) In vivo experiment: 21 adult rats were taken to establish a bilateral tibial defect model. The experimental group (n=7) was implanted with PCL/β-TCP/PDGF BB scaffolds; the control group (n=7) was implanted with PCL/β-TCP scaffolds; the blank group (n=7) was not implanted with scaffolds. At 12 weeks after operation, micro-CT scanning, bone histomorphological observation, and gene detection of osteogenesis and angiogenesis were performed. RESULTS AND CONCLUSION: (1) In vitro experiment: Compared with PCL/β-TCP scaffold, PCL/β-TCP/PDGF BB scaffold could promote the osteogenic differentiation of bone marrow mesenchymal stem cells, promote the proliferation and adhesion of human umbilical vein endothelial cells, and promote vascular endothelial growth factor and CD31 mRNA expression in human umbilical vein endothelial cells. (2) In vivo experiments: Micro-CT scans exhibited that bone defects were obvious in the blank group. A large amount of new bone tissue was visible in both control and experimental groups. The repair effect of the experimental group was more clear. Hematoxylin-eosin staining, Masson and safranin fast green staining displayed that there was no obvious bone tissue formation in the blank group. In the control group, a large amount of mature bone matrix and relatively less immature cartilage tissue were detectable. In the experimental group, a large amount of osteoid tissue and mature cartilage tissue were seen, and most of the medullary cavity was recanalized. RT-PCR detection showed that the mRNA expression levels of bone morphogenetic protein 2, basic fibroblast growth factor, alkaline phosphatase, osteocalcin, vascular endothelial growth factor and CD31 in the experimental group were higher than those in the control group (P < 0.05). (3) It is concluded that compared with PCL/β-TCP scaffold, PCL/β-TCP/PDGF BB scaffold promoted the osteogenic differentiation of bone marrow mesenchymal stem cells, the proliferation, adhesion and expression of angiogenic genes of human umbilical vein endothelial cells, and promoted the repair of bone defects. Figures and Tables | References | Related Articles | Metrics

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Peracetic acid-ethanol treated tendons crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide combined with N-hydroxysuccinimide: morphological features in vitro Ma Rongxing, Li Ruifeng, Zhang Haoran, Xu Mingyou, Zhang Jingyu, Hu Yongcheng 2023, 27 (21):  3307-3313.  doi: 10.12307/2023.455 Abstract ( 109 )   PDF (3171KB) ( 11 )   Save BACKGROUND: Peracetic acid has been proven to effectively inactivate potential microorganisms in allograft tendons, but disrupts intramolecular and intermolecular cross-links of collagen. Therefore, how to weaken or repair this kind of damage and improve the morphological properties of tendon while sterilizing is a problem to be solved. OBJECTIVE: To explore whether 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide can protect tendons treated peracetic acid-ethanol. METHODS: Eighteen New Zealand white rabbits were selected as model animals, and the semitendinosus tendons were cut as experimental materials (n=36). Tendons were divided into three groups (n=12). The tendons in the control group were decellularized and placed in peracetic acid-ethanol solution for sterilization. On the basis of the treatment of the control group, the tendons in the experimental group 1 were placed in MES buffer solution for 24 hours, and then placed in the ethanol cross-linking solution containing 50 mmol/L MES, 2.5 mmol/L 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and 5 mmol/L N-hydroxysuccinimide for 6 hours. On the basis of the treatment of the control group, the tendons in the experimental group 2 were placed in MES buffer solution for 24 hours, and then placed in the ethanol cross-linking solution containing 50 mmol/L MES, 5 mmol/L 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and 5 mmol/L N-hydroxysuccinimide for 6 hours. After treatment, the tendons were sterilized by gamma irradiation and observed by optical microscope, scanning electron microscope, transmission electron microscope, and polarizing microscope. RESULTS AND CONCLUSION: (1) Optical microscope and scanning electron microscope: In the blank group, the collagen fibers were more disordered; tenocytes were scattered; the connection between tendon bundles was loose and the fiber gap was wider; the fibers were entangled together; the waveform was disordered. The parallel arrangement of tendons in the two experimental groups was more uniform, regular and wavy, and the interfiber gap became smaller and the performance in the experimental group 2 was more significant. (2) Transmission electron microscope: Collagen fibril diameter and collagen fibril index in experimental group 2 were greater than those in control group and experimental group 1 (P < 0.05). The average diameter of collagen fibers in experimental group 1 and experimental group 2 was greater than that in the control group (P < 0.05). The density of collagen fibers in the control group was greater than that in the experimental group 1 and the experimental group 2 (P < 0.05). (3) Polarizing microscope: In the three groups, the proportion of type I collagen fibers was relatively large, and the proportion of type III collagen fibers was relatively small. The control group had less fiber density and loose gaps. In the experimental group 1, fiber density increased. The fiber gap of the experimental group 2 was the smallest and the density was the largest. The collagen crimp cycle in the control group was greater than that in the experimental group 1 and the experimental group 2 (P < 0.05). (4) The results showed that 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide combined with N-hydroxysuccinimide could lessen the degree of tendon damage at the microscopic level, and could protect the tendon after peracetic acid-ethanol treatment. 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide concentration of 5 mmol/L had better morphological characteristics than 2.5 mmol/L. Figures and Tables | References | Related Articles | Metrics

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Safety evaluation of electroactive hydrogel in the treatment of complete spinal cord transection in rats Jiang Shengyuan, Deng Bowen, Liu Gang, Fan Xiao, Bai Huizhong, Tao Jingwei, Zhao Yi, Ren Jingpei, Xu Lin, Mu Xiaohong 2023, 27 (21):  3314-3319.  doi: 10.12307/2023.454 Abstract ( 128 )   PDF (1757KB) ( 9 )   Save BACKGROUND: As a biological scaffold, hydrogel has been widely used in the basic research of spinal cord injury. Based on the electrical signal conduction characteristics of spinal cord tissue, electroactive hydrogel has been preliminally explored and applied, but its efficacy and mechanism are not clear yet. OBJECTIVE: To preliminatively explore the potential mechanism of electroactive hydrogel promoting axonal regeneration after spinal cord injury and evaluate the safety and feasibility of conductive hydrogel as biological scaffold for spinal cord injury repair. METHODS: On the basis of methacrylated gelatin hydrogel, conductive particle polypyrrole was added to prepare electroactive hydrogel. Thirty-six adult female SD rats were randomly divided into sham operation group, model group and electroactive hydrogel group, with 12 rats in each group. Only laminectomy was performed in sham operation group. T9 spinal cord was completely transected with 2 mm defect gap in model group and electroactive hydrogel group. The defect gap was filled with electroactive hydrogel immediately after model preparation in electroactive hydrogel group. BBB score was performed on 1, 3, 7, 14 and 28 days after operation. On day 28 after operation, serum inflammatory indexes, tissue morphology of liver, spleen, kidney and spinal cord, microvascular regeneration and axon regeneration were detected. RESULTS AND CONCLUSION: (1) BBB score of electroactive hydrogel group was better than that of model group at 28 days after operation (P < 0.05). (2) C-reactive protein levels in electroactive hydrogel group were significantly lower than those in the model group (P < 0.05). There was no significant difference in erythrocyte sedimentation rate between the two groups (P > 0.05). (3) Hematoxylin-eosin staining showed that there was no inflammatory cell infiltration in liver, spleen and kidney of rats in the three groups. Inflammatory cell infiltration was obvious at the broken end of model group; the cells were disordered and the surrounding tissues dissolved. There were fewer inflammatory cells in electroactive hydrogel group, and cells grew in the electroactive hydrogel group and arranged orderly. Masson staining indicated that a large number of collagen fibers grew into the broken end of rats in model group, while only a small amount of collagen fibers were wrapped around the electroactive hydrogel in electroactive hydrogel group. (4) Immunofluorescence staining results showed that there were fewer vascular endothelial cells and almost no mature neurons in the spinal cord defect in model group, while the vascular endothelial cells in electroactive hydrogel group were significantly more than that in model group, and there were formed vascular contours. The number of neurons was more than that in model group, but the nucleus was pyknotic compared with the sham operation group. (5) Western blot assay showed that the protein expression levels of vascular endothelial growth factor and neurofilament 200 in electroactive hydrogel group were higher than those in model group (P < 0.05). (6) Electroactive hydrogel is safe and effective as biological scaffolds to repair spinal cord injury. The mechanism of promoting axon regeneration may be related to promoting microvascular regeneration and improving microcirculation. Figures and Tables | References | Related Articles | Metrics

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Surface roughness and bacteria adhesion of full zirconia restoration after different polishing treatment Zeng Jindi, Song Jingjing, Zhang Yuhang, Yang Zhengyi, Nie Ermin, Zhang Chunyuan, Jiang Rui 2023, 27 (21):  3320-3324.  doi: 10.12307/2023.174 Abstract ( 118 )   PDF (845KB) ( 11 )   Save BACKGROUND: The polishing treatment on the surface of the crown restoration can effectively reduce pigmentation, adhesion of plaque and abrasion of the jaw teeth.   OBJECTIVE: To investigate the effects of different polishing treatments on the surface roughness and bacterial adhesion of the full zirconia restoration. METHODS: Totally 30 full zirconia specimens with sizes of 10 mm × 10 mm × 2 mm were prepared and divided into 5 groups randomly (n=6): control group (simple glazing treatment), polishing group (green silicon carbide sandstone, Shofu porcelain polishing kit, Ceramaster Polisher polishing), polishing paste group (green silicon carbide sandstone, Softcut PA, Shofu porcelain polishing kit, UltraII emery polishing paste), fine polishing group (green silicon carbide sandstone, Softcut PA, Shofu porcelain polishing kit, Ceramaster Polisher polishing), multi-step fine polishing group (green silicon carbide sandstone + white alumina sandstone, Softcut PA + Softcut PB, Shofu porcelain polishing kit, Ceramaster Polisher polishing). The surface roughness value, surface morphology of each specimens, and colony forming unit of bacteria on the surface of the specimens were detected after treatment.  RESULTS AND CONCLUSION: (1) The surface roughness values of specimens of the five groups from high to low were: polishing group, polishing paste group, multi-step fine polishing group, fine polishing group, control group. The value was higher in the polishing group than that in other four groups (P < 0.05). The value was higher in the polishing paste group than that in the control group, fine polishing group, and multi-step fine polishing group (P < 0.05). (2) Under the electron microscope, the specimens of control group, fine polishing group and multi-step fine polishing group had smooth surface without visible scratches. The specimens of polishing paste group had deep scratches and small particles on the surface. The specimens of polishing group had the roughest surface with noticeable scratches, deep grooves, and many irregular granular protrusions. (3) The colony forming unit in the five groups from high to low was: polishing group, polishing paste group, multi-step fine polishing group, fine polishing group, and control group. The colony forming unit was significantly higher in the polishing group than that in the other four groups (P < 0.01). (4) These results show that both the fine polishing and the multi-step fine polishing can effectively improve the finish and reduce the bacteria adhesion on the surface and have a comparable effect to glazing.  Figures and Tables | References | Related Articles | Metrics

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Preparation and biological evaluation of decellularized dermal matrix hydrogel Xu Xin, Liu Yaowei, Mu Yunping, Wang Jianying, Li Fanghong, Zhao Zijian 2023, 27 (21):  3325-3331.  doi: 10.12307/2023.417 Abstract ( 166 )   PDF (2707KB) ( 18 )   Save BACKGROUND: Recently, decellularized dermal matrix hydrogel has broad application prospects in tissue filling and repair because of its injectable and filling irregular space. Cytocompatibility and biocompatibility are the key to tissue repair. It is significant to explore the compatibility of decellularized dermal matrix hydrogel.  OBJECTIVE: To construct a decellularized dermal matrix hydrogel scaffold for tissue filling and repair. METHODS: An injectable decellularized dermal matrix hydrogel was prepared, and its microscopic morphology was observed under a scanning electron microscope. The decellularized dermal matrix hydrogels with a concentration of 8 and 10 g/L were co-cultured with bone marrow mesenchymal stem cells, separately, and the cell proliferation and cytocompatibility were tested. The decellularized dermal matrix hydrogels with a protein concentration of 0.25 and 0.5 g/L were injected into different subcutaneous parts of the back of the same SD rat separately, and the degradation of the hydrogels was observed 2 and 4 weeks after the operation. Decellularized dermal matrix hydrogels with protein concentrations of 1, 1.5, and 2 g/L were injected into different subcutaneous parts of the back of the same SD rat separately. At 8 and 16 weeks after the operation, the degradation of the hydrogel was observed and histological analysis was performed.  RESULTS AND CONCLUSION: (1) Scanning electron microscopy analysis showed that the decellularized dermal matrix hydrogel exhibited an irregular and randomly oriented porous fibrous structure with different pore sizes. (2) After 1, 3, and 5 days of co-culture, the hydrogels with the two concentrations had no effect on the proliferation of bone marrow mesenchymal stem cells. Live/Dead staining after 1, 2, and 3 days of co-culture showed that the hydrogels with the two concentrations had no effect on the proliferation of bone marrow mesenchymal stem cells, but the cell morphology on the hydrogel changed to some extent. (3) The hydrogel with a protein concentration of 0.25 g/L was degraded after subcutaneous injection for 2 weeks; the hydrogel with a protein concentration of 0.5 g/L was degraded after subcutaneous injection for 4 weeks; the hydrogels with a protein concentration of 1, 1.5, and 2 g/L did not degrade after subcutaneous injection for 16 weeks, and possibly even longer. Hematoxylin-eosin staining showed that after subcutaneous injection for 8 weeks, the hydrogel tissue of the three protein mass concentrations was relatively dense, with a small amount of inflammatory infiltration, and the 2 g/L group had microangiogenesis. After 16 weeks, the hydrogel tissue became loose, and the 1 g/L group was more obvious, and the inflammatory infiltration was alleviated. Immunohistochemical staining showed that the number of microvessels in the hydrogel increased with the increase of injection time. The number of microvessels in the hydrogel increased with the increase of protein concentration. (4) The results confirmed that the injectable decellularized dermal matrix hydrogel had good cytocompatibility and biocompatibility. Figures and Tables | References | Related Articles | Metrics

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Small-sized attached transcutaneous nerve electrical stimulation in the treatment of chronic cervical pain Yao Yuan, Xu Yuanjing, Ren Fuchao, Miao Weiqiang, Wang Jinwu 2023, 27 (21):  3332-3336.  doi: 10.12307/2023.009 Abstract ( 147 )   PDF (772KB) ( 11 )   Save BACKGROUND: Transcutaneous nerve electrical stimulation has the advantages of non-invasiveness and convenience, and is one of the commonly used physical factors for the treatment of chronic neck pain. However, the current clinical use of percutaneous nerve electrical stimulation equipment has high cost and specific site requirements. It is necessary to actively explore economic, convenient and effective methods for the treatment of cervical pain.  OBJECTIVE: To investigate the clinical effect of small-sized attached transcutaneous nerve electrical stimulation combined with cervical health education on chronic cervical pain. METHODS: From November 2020 to July 2021, 22 patients with chronic cervical pain were recruited in the Department of Rehabilitation Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, including 5 males and 17 females, at the age of 18-60 years. On the basis of cervical posture education and cervical muscle home stretching training, a small-sized attached transcutaneous electrical nerve stimulator was used every day for 15 minutes lasting for 2 weeks. The changes of pain visual analogue scale score, muscle pressure pain threshold, and neck disability index were evaluated before treatment, immediately after the first treatment, 1 and 2 weeks after treatment. RESULTS AND CONCLUSION: (1) Compared with baseline score, the pain score evaluated immediately after the first treatment, 1 and 2 weeks after treatment decreased significantly in 22 patients (P < 0.05). The left cervical pain scores decreased immediately and 2 weeks after treatment (P < 0.05). (2) Compared with baseline data, the pressure pain threshold of the left and right trapezius muscles in 22 patients increased significantly 2 weeks after treatment (P < 0.05). Pressure pain threshold at 1 cm from left and right C5C6 spinous process increased significantly 2 weeks after treatment (P < 0.05). (3) Compared with baseline, neck disability index decreased 2 weeks after treatment in 22 patients (P < 0.05). (4) The results showed that small-sized attached transcutaneous nerve electrical stimulation combined with home exercise could remarkably reduce cervical pain immediately and in the short term. The muscle pressure pain threshold and cervical function were also improved in the short term. Figures and Tables | References | Related Articles | Metrics

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Effect of osteoclast TRPV5 channel on in vitro degradation of biological coral artificial bone Cui Hongwang, Wang Liangsheng, Wen Peng, Meng Zhibin 2023, 27 (21):  3337-3342.  doi: 10.12307/2023.413 Abstract ( 129 )   PDF (1413KB) ( 13 )   Save BACKGROUND: Biological coral artificial bone is a good alternative material for repairing long bone defects. However, the degradation and absorption rate of biological coral artificial bone in the human body does not match the growth rate of new bone, which leads to the limitation of its clinical application.  OBJECTIVE: To explore the effect of osteoclast TRPV5 on the degradation of biological coral artificial bone. METHODS: Monocyte macrophage strain RAW264.7 from mouse was inoculated on biological coral artificial bone slices, which were co-cultured with osteoclasts. After the appearance of osteoclasts was observed, the osteoclast-induced differentiation medium containing 0, 50, 500, 5 000 µmol/L ruthenium red (TRPV5 channel inhibitor) was added separately. After culturing for a certain period of time, the expression of TRPV5 channel protein was observed under a laser confocal microscope. The absorption lacuna on the biological coral artificial bone slice was observed under a scanning electron microscope. The expression of TRPV5 channel protein in cells was detected by western blot assay.  RESULTS AND CONCLUSION: (1) Laser scanning confocal microscope: TRPV5 could be expressed on the cytoplasm and membrane of osteoclasts. With the increase of ruthenium red concentration, the expression of TRPV5 on osteoclasts decreased. (2) Scanning electron microscope: Large continuous bone resorption lacuna was seen on the bone slices in the 0 nmol/L ruthenium red group. The bone resorption lacuna on the bone slices in other concentrations of ruthenium red decreased and was scattered, and with the increase of the concentration of ruthenium red, the area of the bone lacuna gradually decreased. (3) Western blot assay: Compared with 0 nmol/L ruthenium red group, the expression of TRPV5 channel protein in other concentrations of ruthenium red groups was significantly decreased (P < 0.05 or P < 0.01). (4) The results confirm that osteoclasts grow well on biological coral artificial bone, and TRPV5 can be used as a target to regulate the degradation rate of biological coral artificial bone. Figures and Tables | References | Related Articles | Metrics

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Repair effects of two kinds of bone repair materials on rabbit femoral defects compared using synchrotron-radiation-based micro-computed tomography Sun Lianlian, Liu Yongchao, Wang Zhixing 2023, 27 (21):  3343-3348.  doi: 10.12307/2023.460 Abstract ( 144 )   PDF (1582KB) ( 12 )   Save BACKGROUND: Bio-oss bone powder and Aobang repair materials are commonly used bone repair materials, but there are few reports on their systematic evaluation of the repair effect of rabbit femoral defect. OBJECTIVE: To systematically evaluate the repair effects of Bio-oss bone powder and Aobang repair materials on femoral defects by using synchrotron-radiation-based micro-computed tomography and histopathological staining.  METHODS: Thirty-two rabbits were randomly divided into the control group (n=12) and the experimental group (n=20) by the random number table method. Two holes with a size of 4 mm (the diameter of the cavity) × 6 mm (hole depth) of penetrating periosteal bone defect were established on the lateral surface of one side of the femoral body. The control group was filled with normal saline. In the experimental group, Bio-oss bone powder was implanted in one of the bone defects, and Aobang repair material was implanted in the other bone defect. After 8 weeks, the effects of the two kinds of bone repair materials were evaluated by visual observation, imaging analysis and histopathological examination.  RESULTS AND CONCLUSION: (1) General view: 8 weeks after the operation, the wounds in the repaired area of bone injury in the experimental group healed well; no infection, suppuration or other symptoms were found, and the animal mobility was significantly better than that of the control group. (2) Imaging examination: synchrotron-radiation-based micro-computed tomography 8 weeks after the operation exhibited that after the implantation of Bio-oss bone powder, there was a large amount of new bone tissue around the bone powder, and the cavity of the bone defect was large, which was not completely filled by the new bone tissue. After the implantation of the Aobang repair material, a large amount of new bone tissue at the bone defect cavity was formed around the repair material. 3D reconstruction showed that both bone filling materials could contact with local bone wound tissue, promote the surrounding osteogenesis to differentiate into new bone tissue and blood vessel formation, and achieve bone repair effect. The new bone around the Aobang repair material was more closely connected with the surrounding bone tissue. 256 iCT scan showed that the CT value of the Aobang repair material side at 8 weeks after operation was higher than that of the Bio-oss bone powder side (P < 0.05). (3) Histopathology: At 8 weeks after operation, hematoxylin-eosin staining showed that new bone tissue could be seen around the side of the Bio-oss bone powder. Bone tissue formed by bone matrix could be seen around the Aobang repair material; the new bone tissue was complete and coherent, and some of the new bone had invaded into the Aobang repair material. (4) These results suggest that Aobang repair material can promote the formation of new bone and damage repair; synchrotron-radiation-based micro-computed tomography echoes the traditional hematoxylin-eosin staining, and it is a good method to evaluate the effect of bone powder repair. Figures and Tables | References | Related Articles | Metrics

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Physical and chemical properties of porcine dermis matrix affected by process integration for decellularization, viral inactivation and sterilization Huang Senli, Sun Haigang, Sun Wenquan 2023, 27 (21):  3349-3355.  doi: 10.12307/2023.170 Abstract ( 119 )   PDF (1181KB) ( 11 )   Save BACKGROUND: Process integration of decellularization, antigen removal, viral inactivation and sterilization is essential for producing regenerative biomaterials that meet clinical requirements.  OBJECTIVE: To systematically compare the effects of two combined processes of decellularization, antigen removal, virus inactivation and sterilization on the physicochemical properties of porcine dermal matrix.  METHODS: Fresh porcine dermis was obtained and processed by two processes into acellular matrices. (1) Method A: 1% Triton X-100, DNase and RNase, and 1% tributyl phosphate were applied for decellularization, 1% peracetic acid and 25% ethanol for viral inactivation, and gamma-irradiation for terminal sterilization. (2) Method B: Dispase II, 0.5% Triton X-100 and DNase were used for decellularization, α-galactosidase for the antigen removal, 0.1% peracetic acid for viral inactivation and gamma-irradiation terminal sterilization. Porcine dermal matrices prepared by two methods were characterized.  RESULTS AND CONCLUSION: (1) The collagen content of group A was lower than that of group B. The contents of elastin and sugar of group A were higher than those of group B. The material hardness value of group A was higher than that of group B. The drapability of the matrix material in group A was poor and the flexibility of the matrix material in group B was better. (2) The decellularization of group A did not affect the thermal stability of the matrix material. In group B, decellularization slightly reduced the thermal stability of the matrix material. After gamma ray sterilization, the thermal stability of the matrix material in group A decreased greatly and the thermal stability of the matrix material in group B decreased very little. (3) Compared with group B, the tensile strength and elasticity of the matrix material in group A were smaller. In vitro enzymatic degradation experiments showed that the matrix materials in group A had strong resistance to collagenase degradation, were sensitive to trypsin and were easily degraded; the matrix materials in group B were the opposite. (4) Scanning electron microscope showed that after sterilization by gamma rays, the three-dimensional structure of collagen could not be seen in the matrix material of group A; the collagen fibers were densely arranged, and there was a non-fibrous structural gel-like substance between the collagen fibers. In group B, the structure of collagen fibers in the matrix material was clear, and there was no non-fibrous structural glue-like substance between the collagen fibers. Hematoxylin-eosin staining and trichrome staining showed that after sterilization by gamma rays, a few nuclei were visible in the matrix material of group A; the collagen fibers were closely arranged, and the material was dense. The matrix material in group B had no nucleus and retained a good three-dimensional spatial structure of collagen fibers. (5) The results suggest that different processes have great influences on the physical and chemical properties of derived acellular matrices. Method B is effective in decellularizing and de-antigening and retains intact natural tissue matrix. Method A is more destructive to the material and results in lower collagen content, scratchability, thermal stability and poorer biomechanical properties compared with the Method B.  Figures and Tables | References | Related Articles | Metrics

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Design and manufacturing error and implant accuracy of tooth-supported surgical template Xu Liangwei, Zhang Kunling 2023, 27 (21):  3356-3360.  doi: 10.12307/2023.466 Abstract ( 108 )   PDF (1200KB) ( 15 )   Save BACKGROUND: The implant template can effectively transfer the implant designed position to the patient’s jaw. It helps implant avoid important anatomical structures such as nerve and maxillary sinus, and effectively reduces the risk of surgery. Therefore, the accuracy of implant template surgery is particularly important.  OBJECTIVE: To assess the design and manufacturing error of the tooth-supported surgical template and its implant accuracy in the fully positioned state.  METHODS: A patient with missing teeth underwent a cone beam CT and a plaster model was established. According to the patien’s oral situation, implant plan with special positioning surface tooth-supported template was designed and implant template was made. Stereo Lithography Apparatus rapid prototyping technology was used to fabricate 10 templates and three-dimensional laser scanning was performed. After matching the scanning data with designed template model data, manufacturing error analysis was carried out. In addition, the 10 manufactured templates were worn on the patient’s plaster model to simulate implant position, and the simulated implant positions were matched with initial implant positions in the design plan for accuracy analysis. RESULTS AND CONCLUSION: (1) The mean positive deviation of the template was 0.093 mm; the mean negative deviation was 0.092 mm, and the mean standard deviation was 0.169 mm. (2) The simulated implant accuracy results showed that the neck center deviation of implant 12 was (1.172±0.283) mm; the top center deviation was (1.339±0.283) mm; the central axis angle deviation was (0.365±0.228)°; the neck center deviation of implant 21 was (1.274±0.379) mm; the top center deviation was (1.461±0.404) mm, and the center axis angle deviation was (0.643±0.276)°. (3) These results indicate that the design and manufacturing error of tooth-supported template with a specific positioning surface has a significant impact on implant accuracy.  Figures and Tables | References | Related Articles | Metrics

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Role of chitosan and its derivatives in the field of oral antibacterial Liu Zhuoran, Li Yumei, Liu Junyan, Yin Tong, Jiang Ming, Li Yourui 2023, 27 (21):  3361-3367.  doi: 10.12307/2023.136 Abstract ( 168 )   PDF (936KB) ( 27 )   Save BACKGROUND: There are many kinds of microorganisms in the mouth, forming a complex microenvironment, and microflora disorders can cause a series of oral diseases. At present, the use of antibacterial drugs is mainly oral or topical, but due to the rapid decomposition and release of antibiotics, the resistance of pathogenic microorganisms to antibiotics continues to increase, often resulting in poor clinical efficacy. In recent years, studies have found that chitosan and its derivatives have good antibacterial activity. With the development of nanotechnology, chitosan and its derivatives in different forms are widely studied in the field of antibacterial. OBJECTIVE: To review the main antibacterial mechanisms of chitosan and its derivatives and their application in the field of oral antimicrobials in different forms.  METHODS: The computer was applied to search articles related to chitosan and its derivatives in the field of oral antimicrobials on PubMed, Web of Science and CNKI databases. The search terms were “chitosan, chitosan derivative, antibacterial activity, antibacterial mechanism, oral” in Chinese and English. The retrieval time was from the establishment of the database to April 2022.  RESULTS AND CONCLUSION: (1) Chitosan, also known as deacetylacetyl chitin, is the primary derivative of chitin after deacetyl group, and is the only cationic alkaline polysaccharide found so far. Chitosan and its derivatives have been widely studied in the field of oral antibacterial as nano-antibacterial agents. (2) The antibacterial mechanism most recognized by chitosan and its derivatives at present is electrostatic action, that is, the interaction between the positive charge carried by the chitosan molecule and the negative charge carried by the microbial cell membrane, which changes the permeability of the cell and thus achieves the antibacterial purpose. (3) The antibacterial properties of chitosan are related to a variety of factors. These factors mainly include: microbial origin, chitosan intrinsic factors (including: deacetylity and concentration, molecular weight, and polymerization degree). Different sources of chitosan and irregular specific environmental factors (such as temperature and pH value) will also greatly affect the antibacterial ability of chitosan. (4) Chitosan and its derivatives can be used as carriers of antibacterial drugs on the one hand to promote the healing of mouth ulcers; on the other hand, polymer composite scaffolds can be formed as greener oral antibacterial preparations, enhancing the antibacterial properties of oral materials in the form of nano-antibacterial fillers. In addition, it can also be used as nano-composite films and coatings to inhibit the production of biofilms of common oral strains. (5) In addition, the antibacterial application of chitosan and its derivatives is still in the experimental stage, and its antibacterial mechanism is not yet fully understood, so further research is needed to confirm the biosafety of chitosan and its derivatives.  Figures and Tables | References | Related Articles | Metrics

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Application of inorganic nonmetal biomaterials in the treatment of osteosarcoma and the regeneration of tumor-related bone defects Niu Lin, Mei Yukun, Zou Rui, Zhang Yuwei, Zhang Yifei, Hao Yaqi, Dong Shaojie 2023, 27 (21):  3368-3374.  doi: 10.12307/2023.110 Abstract ( 136 )   PDF (924KB) ( 14 )   Save BACKGROUND: Osteosarcoma is a common clinical disease. In recent years, the application of inorganic nonmetal biomaterials in the treatment of osteosarcoma has become a new way to overcome the bottleneck of traditional treatment. OBJECTIVE: To introduce the application of inorganic nonmetal biomaterials in the diagnosis and treatment of osteosarcoma, and to summarize its current research status and future application prospects. METHODS: A computer-based online search of Web of Science, PubMed, and CNKI was performed to retrieve articles regarding inorganic nonmetal biomaterials in the diagnosis and treatment of osteosarcoma and mainly retrieve experimental articles on the preparation, application and animal cell experiments of inorganic non-metallic biomaterials for osteosarcoma. Finally, 69 articles were included for review.  RESULTS AND CONCLUSION: (1) Inorganic nonmetal biomaterials have excellent characteristics of good biocompatibility, stable physical and chemical properties, biodegradability and promoting osteogenesis. (2) The inherent shortcomings of inorganic nonmetallic materials, such as weak anti-fracture performance, high preparation process requirements, low loading dose of drugs and bioactive molecules, limit the application in the cases of bone defects in load-bearing areas and controlling drugs releasing. (3) At present, inorganic nonmetal biomaterials such as nano drug loading platform, biological implantation scaffold and material surface coating are wildly used in the treatment of osteosarcoma, which realizing new diagnosis and treatment strategies in chemokinetic therapy, nano targeted diagnosis and treatment, catalytic therapy, immunotherapy and tumor hyperthermia through functional modification. However, these researches mostly stay in the basic experimental stage for lacking of the clinical trial data support. (4) Improving the preparation process of inorganic nonmetallic materials, exploring new functional modification strategies and further extensive clinical evaluation are the key to turn the basic research into clinical practice and promote the sustainable development of inorganic nonmetallic materials. Figures and Tables | References | Related Articles | Metrics

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Role and mechanism of polyphosphate in bone tissue regeneration Cao Jin, Wang Ansu, Huang Nijiao, Wu Fujun, Chen Ping, Li Chengmei, Wang Xin 2023, 27 (21):  3375-3381.  doi: 10.12307/2023.178 Abstract ( 139 )   PDF (1290KB) ( 14 )   Save BACKGROUND: Regenerative repair of large bone defects remains one of the great challenges for clinical orthopedic surgeons. Polyphosphates not only play an important role in osteoblast development and growth factor release, but also regulate osteogenic activity by affecting the structure of local blood clots. OBJECTIVE: To summarize the relationship between polyphosphates and bone tissue regeneration and to understand the mechanism of polyphosphates in osteogenesis.  METHODS: CNKI, Wanfang, VIP, CBM and PubMed databases were searched for articles regarding research progress of polyphosphates in bone tissue regeneration. After preliminarily screened by reading abstracts, a total of 80 articles were finally included for review.  RESULTS AND CONCLUSION: The mechanisms of action of polyphosphates in bone tissue regeneration can be classified into the following categories: (1) Polyphosphates enhance fibroblast growth factor-2-mediated cellular signaling pathways by inducing the expression of the related transcription factors Runx2, matrix metalloproteinase-1, osteopontin, osteocalcin and osteoprotegerin related genes, enhance the affinity between fibroblast growth factor-2 and the receptor, activate fibroblast growth factor-mediated cellular signaling pathways, and promote osteoblast differentiation of mesenchymal stem cells. (2) During osteoblast metabolism: polyphosphate catabolism provides a source of energy and regulation of calcitonin, osteogenesis-associated transcription factors, bone sialic acid protein, and tissue non-specific alkaline phosphatase gene expression, promoting cell mineralization. (3) Due to the presence of competitive inhibition: polyphosphate inhibits the enzymatic activity of tartrate resistant acid phosphatase in osteoclasts, contributing to the decrease in bone resorption activity of osteoclasts. (4) Polyphosphate activates the nuclear factor κB signaling pathway and upregulates the expression of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and selectin-E, enhancing monocyte adhesion to endothelial cells. (5) Polyphosphate also binds to histone 4 and high mobility group B1 with high affinity and enhances the expression of vascular permeability signaling factors, cell surface adhesion molecules, inflammatory cell migration, and apoptosis. (6) Polyphosphate regulates the inflammatory response by modulating the PI3K/AKT and PLC/PKC/Ca2+ signaling pathways and bradykinin system in endothelial cells. (7) By promoting the formation of coarse fibers of a blood clot, polyphosphates increase the pore size of the fibrous clot, promote the infiltration of relevant cells and factors, and promote local vascularization, and the repair and regeneration of bone tissue.   Figures and Tables | References | Related Articles | Metrics

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Potential of collagen peptide to improve skin and the countermeasures to improve its bioavailability Bai Lei, Wang Yang, Tian Xiaojing, Wang Wenhang 2023, 27 (21):  3382-3390.  doi: 10.12307/2023.458 Abstract ( 196 )   PDF (1591KB) ( 32 )   Save BACKGROUND: Collagen peptide is a low molecular active peptide obtained by hydrolysis of collagen. It can be digested and absorbed, and participate in protein synthesis and metabolism in the human body. It has a positive effect on skin health. However, the absorption and delivery mechanism of collagen peptides is not completely clear, and another problem is its low bioavailability. OBJECTIVE: To explore the potential measures to increase the bioavailability of collagen peptides for promoting skin health. METHODS: The articles related to the preparation, composition, digestion and bioavailability of collagen peptide, skin structure, photoaging and natural aging, transport mechanism of collagen peptide by oral in vivo, transdermal absorption mechanism of collagen peptide, and synergistic absorption of collagen peptide with other substances, were searched on ScienceDirect, PubMed, CNKI, Sci-Hub, and Baidu Academic Database from January 2009 to March 2022. The main keywords used were “collagen, collagen peptide, preparation of collagen peptide, photoaging, percutaneous absorption of collagen peptide” in Chinese and “collagen, collagen peptide, preparation of collagen peptide, photoaging, oral absorption” in English. Finally, 82 articles were included for review. RESULTS AND CONCLUSION: (1) Photoaging and natural aging cause skin tissue damage. Collagen peptides can be transported to the skin through the blood after oral gastrointestinal digestion, and build skin tissue through internal molecular mechanisms, and can also be absorbed through the skin surface to have a positive effect on the dermis. (2) At present, the bioavailability of oral collagen peptide is low, and its delivery mechanism is mainly concentrated in the gastrointestinal stage, and there is also the problem of excessive epidermal resistance in percutaneous absorption. (3) The source, amino acid composition, peptide sequence, molecular weight and dosage of collagen peptide and synergistic absorption with different substances or enzyme cofactors should be paid more attention, looking for more high-quality delivery carriers to improve the bioavailability of collagen peptides. (4) For percutaneous absorption, advanced technology or improved physical and chemical methods should be applied to reduce skin physical resistance or improve molecular penetration efficiency. (5) In future, both oral and percutaneous absorption of collagen peptide could be used to recover skin tissue problems caused by photoaging and natural aging more quickly and effectively.  Figures and Tables | References | Related Articles | Metrics

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Effects of scaffolds on angiogenic microenvironment and its mechanism Zhang Yi, Ren Sicong, Huangfu Huimin, Xu Jing, Yang Zhen, Zhou Yanmin 2023, 27 (21):  3391-3397.  doi: 10.12307/2023.420 Abstract ( 129 )   PDF (1402KB) ( 11 )   Save BACKGROUND: Angiogenesis is the key to tissue repair and regeneration, but vascularization is also a problem of tissue engineering. It is an effective way to solve the problem of angiogenesis by designing biomimetic scaffold materials and regulating the microenvironment of angiogenesis.  OBJECTIVE: To review the effects and mechanisms of scaffolds on the angiogenic microenvironment, providing ideas for the design of biomaterials in regenerative medicine. METHODS: PubMed and CNKI were searched using the Chinese keywords of “angiogenesis, scaffolds” and English keywords of “angiogenesis, scaffolds, tissue engineering, microenvironment”. The search time limit was extended for some classical literature. The abstracts and contents of the retrieved literature were analyzed, and 62 eligible articles were obtained as per inclusion and exclusion criteria. RESULTS AND CONCLUSION: (1) A complete vascular network is a key to the success of tissue engineering. To generate a complete vascularized network, the vascular niche must be simulated and reproduced. Vascular niches include the biophysical and biochemical microenvironments surrounding blood vessels. (2) The design of the scaffold is necessary to optimize the angiogenesis signaling pathway to support the attachment, proliferation, differentiation, or migration of vascular cells in tissues. (3) Adjusting the biophysical and biochemical characteristics of the scaffold, such as hardness, surface morphology, pore structure, functional biomolecules and angiogenesis factor of load, and so on, can improve the body’s growth potential, driven by endogenous cell proliferation and migration, implemented as vascular microenvironment simulation and reproduction, improving the angiogenesis. (4) Therefore, the precise regulation of the vascular microenvironment by biophysical and biochemical cues of engineered biomaterials has great prospects in the construction of tissue engineering functional vascular networks.  Figures and Tables | References | Related Articles | Metrics

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Effect of magnesium alloy biomaterial degradation on endothelialized cells Dong Shiwu, Zhou Lanxi, Shao Lu, Yu Zhengwen 2023, 27 (21):  3398-3406.  doi: 10.12307/2023.467 Abstract ( 133 )   PDF (1875KB) ( 15 )   Save BACKGROUND: Magnesium alloys have been known as the revolutionary metallic materials because of their excellent biocompatibility and degradability. The effect of its degradation on endothelialization has great research significance.  OBJECTIVE: To review the research progress of magnesium alloy materials.  METHODS: The articles were searched by using the databases of PubMed, CNKI, Web of Science, and Elsevier. The key words were “Metallic biomaterials, Magnesium alloys, Vascular stents, Endothelialization, Animal experiments, In vitro” in Chinese and English. As a result, 116 articles were applied after reading and analyzing the titles and abstracts of the articles published between 2015 and 2022. RESULTS AND CONCLUSION: Appropriate concentrations of magnesium ions can enhance the proliferation of endothelial cells and smooth muscle cells during the degradation of magnesium alloys. The effect of magnesium ions on endothelialization is basically recognized. Nevertheless, too fast degradation rate is the biggest problem of magnesium alloys. If the concentration of magnesium ions is too high, cytotoxicity will occur. Therefore, current studies mostly focus on improving its degradation and improving its biocompatibility. At present, the common methods to improve the degradation of magnesium alloys include purification, alloying and surface modification, all of which can improve their corrosion resistance. The alloying of different elements can improve magnesium alloys in different ways. In the future, different alloyed magnesium alloys can be used according to different needs to adapt to the situation of clinical patients. In addition to introducing other elements, improving the production process of magnesium alloys to solve the degradation problem may also be a method worth trying. Figures and Tables | References | Related Articles | Metrics

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Antibacterial mechanism and application of nanomaterials in oral infectious diseases Luo Tingyan, Gu Yu, Qin Xiaofei 2023, 27 (21):  3407-3414.  doi: 10.12307/2023.133 Abstract ( 147 )   PDF (1248KB) ( 19 )   Save BACKGROUND: Oral infection has always been an important factor threatening human health, and it is one of the main research contents in the field of stomatology. Nanomaterials, as an emerging antibacterial material with excellent therapeutic effect, have gradually become a popular choice for the prevention and treatment of oral bacterial infections because of their broad antibacterial spectrum, strong antibacterial effect, good stability, and not easily affected by antibiotic resistance mechanisms.  OBJECTIVE: To summarize the antibacterial mechanism of nanomaterials and the research status of oral infectious diseases, and provide new research directions and basis for the prevention and treatment of oral bacterial infection.  METHODS: In February 2022, the first author used a computer to search for relevant literature published from January 2000 to February 2022 on PubMed, Wanfang Data Knowledge Platform and CNKI database, using “nanomaterials, bacteriostatic, oral infection” as the English and Chinese search terms. Finally, 97 articles were included for analysis.  RESULTS AND CONCLUSION: (1) The main antibacterial mechanisms of nanomaterials are: surface contact, immersion-penetration, catalytic oxidation, and photothermal bacterial lysis, through which they have good antibacterial performance in oral infectious diseases. (2) Compared with traditional materials, nanomaterials have a high probability of contacting pathogenic bacteria and have strong bacteriostatic ability. These advantages make them achieve good results in the prevention and treatment of oral infections. However, in terms of clinical application, nanomaterials still have many problems, for example: metal nanoparticles have poor biocompatibility and concentration dependence; the biosafety evaluation system of systematic science is not yet mature, and the process from laboratory to clinical transformation is often accompanied by optimization of parameters and even changes in methods. There are not many types of nano-formulations that can be practically applied in clinical practice. Although there are nanomaterials such as liposomes that can be used for large-scale production, large-scale and reproducible synthesis of nanoparticles will be more difficult when multi-step modification or complex technology is involved. At present, there are still many nanomaterials whose preparation processes are not perfect, and large-scale production cannot be achieved. The application potential needs to be further explored in the future. Figures and Tables | References | Related Articles | Metrics

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Characteristics and application of bone repair materials of metal ion doped hydroxyapatite Qi Junqiang, Guo Chao, Niu Dongyang, Wang Haotian, Xiao Bing, Xu Guohua 2023, 27 (21):  3415-3422.  doi: 10.12307/2023.179 Abstract ( 160 )   PDF (892KB) ( 33 )   Save BACKGROUND: Autologous and allogeneic bone currently used for bone repair has limited sources, complications in the donor area, potential risk of disease transmission, immune rejection, and high prices, which have limited clinical applications. Artificial bone repair materials have been widely studied as bone graft replacement materials. OBJECTIVE: To summarize the current status of research on metal ion-doped modified hydroxyapatite for bone tissue repair. METHODS: The articles collected in PubMed, Web of Science, CNKI and Wanfang databases were searched from January 2000 to May 2022. The Chinese and English search terms were “metal ion, hydroxyapatite, doping modification, bone repair”. Finally, 61 articles were included for review. RESULTS AND CONCLUSION: (1) Ion doped hydroxyapatite has good characteristics. Strontium can enhance the osteogenesis of osteoblasts and inhibit osteoclast mediated bone resorption. Strontium doped hydroxyapatite has unique advantages in the repair of osteoporotic bone defects. (2) Copper, zinc, silver, magnesium and iron have certain antibacterial activity, among which silver and zinc have excellent antibacterial activity. Doping modified hydroxyapatite is of great significance for the prevention and treatment of orthopedic infections. (3) Copper can promote the migration of vascular endothelial cells and increase angiogenesis. Copper doped hydroxyapatite can be used to repair bone tissue lacking blood vessels. Barium has developing property, and it can be compounded with hydroxyapatite and other materials to prepare developing bone repair materials. (4) Strontium Iron Co doped hydroxyapatite can regulate cellular immunity and promote angiogenesis and bone formation. Magnesium, zinc strontium doped hydroxyapatite can induce a weak alkaline environment conducive to osteogenesis, and has excellent osteogenic ability. (5) A certain amount of magnesium doped hydroxyapatite has the compressive strength matching with cortical bone, and is expected to be used for bone tissue repair in weight-bearing sites. Low concentration ion doping can improve the mechanical properties and osteogenic activity of hydroxyapatite, and endow it with antibacterial activity, angiogenesis promotion, immune regulation, and so on. (6) When the ion concentration is too high, it will produce toxic effects. At present, there is no final conclusion about the optimal doping concentration of each ion, which needs to be further studied in the future. (7) The mechanism of ion involvement in bone metabolism and whether it will affect other cell activities need to be explored. How to realize the slow degradation of implant materials and the slow release of metal ions to match the process of bone repair needs to be further studied. (8) Optimizing the synthesis method and ion doping technology of hydroxyapatite to prepare materials that match the mechanical properties of natural bone is a research direction in the future. Figures and Tables | References | Related Articles | Metrics

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Bioactive scaffolds in repairing osteoporotic bone defects Hou Jianming, Li Qi 2023, 27 (21):  3423-3429.  doi: 10.12307/2023.457 Abstract ( 136 )   PDF (1164KB) ( 16 )   Save BACKGROUND: With the development of chemical synthesis technology, according to the characteristics of bioactive scaffolds, the fabrication of multicomponent and multifunctional composite scaffolds by material combination and material design to repair osteoporotic bone defects has become a research hotspot. OBJECTIVE: To introduce bioactive bone tissue engineering scaffolds, discuss and summarize the application of different scaffold materials and their designs in repairing osteoporotic bone defects.  METHODS: PubMed, Web of Science, Springerlink, Medline, Wanfang and CNKI databases were retrieved with “osteoporosis, bone defect, scaffold” as Chinese and English key words for relevant articles on the repair of osteoporotic bone defects with bioactive scaffolds published from 2008 to 2022. RESULTS AND CONCLUSION: The implantation of bioactive scaffolds has brought a new method for repairing osteoporotic bone defects, such as metal materials, bioceramics, polymers and other bioactive scaffolds, which have a good role in promoting bone regeneration. However, in the case of unbalanced bone remodeling in osteoporosis, the ability of single-material scaffolds to promote bone regeneration is limited, and poor bone integration often occurs. According to the characteristics of ideal scaffolds and the advantages and disadvantages of various materials, researchers designed and made a series of functional bioactive composite materials to improve bone remodeling and enhance bone integration by incorporating bioactive substances into scaffolds through material combination and material design. With the in-depth understanding of various types of bioactive scaffold materials, their advantages, disadvantages and limitations will be clarified. Based on the idea of scaffold design, from single component to multi-component combination, through surface modification, 3D printing and other means, the bioactive scaffolds will be gradually applied in the treatment of osteoporotic bone defects in a more multifunctional and efficient manner.  Figures and Tables | References | Related Articles | Metrics

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Research progress on antibacterial properties of medical copper-containing titanium alloys Shen Yong, Liu Shizhang 2023, 27 (21):  3430-3437.  doi: 10.12307/2023.131 Abstract ( 127 )   PDF (1376KB) ( 11 )   Save BACKGROUND: As the main materials of orthopedic implants, titanium and its alloys, widely used in many medical fields including orthopedics, have also increased with the wide application of implant-related infections. Different preparation methods are used to add excellent and clear antibacterial metal copper into them, which does not affect the biomechanical properties. Simultaneously, it has a certain antibacterial ability. OBJECTIVE: To review the research progress and development trend of antibacterial properties of medical titanium alloys with copper. METHODS: Relevant articles published from January 2003 to March 2022 were searched by computer on PubMed and Web of Science databases using the search terms “titanium alloy, copper, antibacterial, surface modification, coating”. Totally 76 articles selected according to the inclusion and exclusion criteria were analyzed and discussed. RESULTS AND CONCLUSION: (1) In vitro and in vivo antibacterial experiments of titanium alloys with copper showed good antibacterial properties, and with the increase of copper content, the antibacterial properties became more obvious. (2) There are still many problems to be solved: exploring and optimizing the content and methods of adding copper. Appropriate preparation process to balance the antibacterial properties, biocompatibility and mechanical properties of the alloy requires further experiments; whether the micro-damage on the surface of the alloy by the surface modification will adversely affect the alloy; the control of the release rate of copper ions and how to avoid the sudden release of copper ions in large quantities in the early stage. Figures and Tables | References | Related Articles | Metrics

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Application of Chinese medicines of tonifying kidney and strengthening bones in the repair of segmental bone defects using bone tissue engineering scaffolds Xiong Wei, Yuan Lingmei, Qian Guowen, Huang Jinyang, Pan Bin, Guo Ling, Zeng Zhikui 2023, 27 (21):  3438-3444.  doi: 10.12307/2023.510 Abstract ( 148 )   PDF (964KB) ( 15 )   Save BACKGROUND: Segmental bone defects are a challenging orthopedic problem and the existing treatment methods are not effective. Bone tissue engineering techniques have shown great potential in the repair of segmental bone defects; however, the osteogenic properties of artificial scaffolds alone are often insufficient to meet the needs of bone defect repair and the loading of growth factors is expensive and unstable. Chinese medicines are widely available and inexpensive and those with the active ingredients of “tonifying kidney and strengthening bones” have the potential to act as exogenous growth factors. Therefore, the composite scaffolds of Chinese medicines have shown good bone tissue repair effects. OBJECTIVE: To introduce several commonly used bone tissue engineering scaffold materials as well as some representative drugs of tonifying kidney and strengthening bones, such as Rhizome Drynariae, Epimedium, and Eucommia, that are used combined with scaffold materials, and discuss the potential of Chinese medicines with the active ingredients of “tonifying kidney and strengthening bones” in the repair of segmental bone defects using bone tissue engineering scaffolds.  METHODS: The first author searched for relevant literature (published from 2007 to 2022) regarding the use of Chinese medicines of “tonifying kidney and strengthening bones” in the repair of segmental bone defects using bone tissue engineering scaffolds in CNKI, WanFang, PubMed, and Web of Science. Search terms included “Chinese medicine, Tonifying kidney, Drynariae, Epimedium, Eucommia, Bone defects, Bone repair, Bone tissue engineering, Scaffold” in Chinese and English. RESULTS AND CONCLUSION: (1) The existing bone tissue engineering scaffold materials include bioceramic materials, medical metal materials, and polymer materials, which can be used in combination to compensate for the performance deficiencies of a single material as per the difference in their properties. (2)Exogenous growth factors combined with bone tissue engineering scaffolds are highly effective in repairing segmental bone defects, but growth factors are unstable and expensive. (3) Modern pharmacology has found that Chinese medicines of tonifying kidney and strengthening bones can significantly promote the osteogenic differentiation of bone marrow mesenchymal stem cells, which can replace the role of growth factors in bone tissue engineering scaffolds. (4) The combination of Chinese medicines of tonifying kidney and strengthening bones and its active ingredients with scaffold materials to produce composite scaffolds has shown unique advantages in the repair of segmental bone defects and has great potential for application. Figures and Tables | References | Related Articles | Metrics