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28 October 2023, Volume 27 Issue 30 Previous Issue    Next Issue

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Correlation between CT value of vertebral body partition and bone cement distribution after percutaneous vertebroplasty Guan Jianbin, Feng Ningning, Yu Xing, Liu Tao, Jiang Guozheng, Yang Yongdong, Zhao He 2023, 27 (30):  4757-4762.  doi: 10.12307/2023.809 Abstract ( 245 )   PDF (1024KB) ( 40 )   Save BACKGROUND: The ideal distribution in percutaneous vertebroplasty is to make the bone cement diffuse and evenly distributed in the vertebral body as much as possible, to avoid local agglomeration and cause uneven stress distribution in the injured vertebra and fracture again. The difficulty of clinical practice is determining how to distribute bone cement to achieve the most ideal state. OBJECTIVE: To investigate the clinical significance and distribution characteristics of CT values in the compression fracture vertebra and L1 in patients with osteoporotic vertebral compression fractures.  METHODS: From February 2021 to February 2022, 47 patients with osteoporotic vertebral compression fractures were selected at Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, 22 males and 25 females, aged (71.3±8.8) years. All patients received percutaneous vertebroplasty. CT values of different regions in injured vertebra and L1 vertebra were measured before operation. Patients were divided into high CT value injection group (n=24) and low CT value injection group (n=23) according to the relative high or low CT value of the area where the puncture needle tip was located during the operation. After percutaneous vertebroplasty, the distribution of bone cement, Cobb angle of kyphosis, anterior edge and middle height of injured vertebral body were measured.  RESULTS AND CONCLUSION: (1) Eight of the 47 patients affected L1 osteoporotic vertebral compression fractures. The CT value of the L1 vertebral body region in the middle 1/3 area was significantly higher than that of the upper and lower 1/3 areas in 47 patients (P < 0.05). The CT value of the anterior half of the vertebral body was lower than that of the posterior half (P < 0.05). The CT value of the upper 1/3 areas of the compression fractures vertebra was significantly higher than that of the middle and lower 1/3 areas (P < 0.05), and the CT value of the anterior half of the vertebral body was lower than that of the posterior half (P < 0.05). (2) Cobb angle of kyphosis, anterior edge and middle height of injured vertebral body in high CT value injection group and low CT value injection group after operation were significantly improved compared with those before operation (P < 0.05); there was no significant difference between the two groups (P > 0.05). (3) The distribution of bone cement in 24 cases of high CT value injection group was diffuse type, while in 23 cases of low CT value injection group, the distribution of bone cement was diffuse type in 2 cases and non-diffuse type in 21 cases. There was a difference in the distribution of bone cement between the two groups (P < 0.05). The point biserial correlation analysis showed that there was a significant positive correlation between the type of bone cement dispersion and the relative CT value of the injection area (r=0.918, P < 0.05). (4) These findings confirm that CT values in the L1 vertebra and the injured vertebra have a specific regional distribution pattern in patients with osteoporotic vertebral compression fractures. There is a correlation between the CT value in the region where the needle tip is located and the type of bone cement distribution in percutaneous vertebroplasty. The tip of the puncture needle is placed in an area with a high CT value, which promotes the uniform diffusion of bone cement throughout the vertebral body.  Figures and Tables | References | Related Articles | Metrics

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Finite element analysis of biomechanical effects of bone cement dispersion type on the reinforced vertebrae Wu Zhihua, Li Ren, Pan Huiling, Fan Fengjie, Jiang Xiaobing, Tang Fuyu 2023, 27 (30):  4763-4768.  doi: 10.12307/2023.831 Abstract ( 273 )   PDF (1438KB) ( 102 )   Save BACKGROUND: When percutaneous vertebral augmentation is performed for osteoporotic vertebral compression fractures, the four main types of cement dispersion type on the reinforced vertebrae are central separation, central integration, anterior separation, and uneven separation. At present, no relevant biomechanical studies have been found to compare the biomechanical effects of four cement dispersion types on the reinforced vertebrae.  OBJECTIVE: To analyze the effects of cement dispersion types on biomechanical characteristics of the reinforced vertebrae using the three-dimensional finite element analysis method.  METHODS: A three-dimensional finite element model of the thoracolumbar segment of thoracic 12 osteoporotic vertebral compression fracture was constructed, and then four models were obtained by simulating four cement dispersion types: central separation, central integration, anterior separation and uneven separation. The material property parameters, and boundary conditions were set, and loads (a vertical downward load of 260 N continuously on the T10 upper-end plate, and simultaneously, 10 N • m moments of flexion, extension, left and right bending, and left and right rotation) were applied, and data were imported to LS-DYNA software for a solution. RESULTS AND CONCLUSION: (1) Under all loading conditions, the stress of the uneven separation model was the largest. The maximum stress of bone cement in the uneven separation model was 4.4, 8.6 and 4.8 times higher than that in the central separation model, the central integration model and the anterior separation model respectively. The maximum Von Mises stress of bone cement was the largest in the left flexion model with central separation, anterior separation and uneven separation. The maximum Von Mises stress of bone cement in the right flexion of the central integration model was the largest. The maximum Von Mises stress of bone cement was the smallest when all models were rotated left and right. (2) The maximum Von Mises stress at the cancellous bone cement interface of the uneven separation model was smaller than that of the other models when rotated from left to right. The maximum Von Mises stress at the cancellous bone cement interface of each model was similar under other working conditions. The maximum Von Mises stress at the cancellous bone cement interface was the largest during the left and right flexion of the four models. (3) The maximum Von Mises stress trends of upper endplates and lower endplates of T12 models were similar, and there was no significant difference under the same working conditions. Under all loading conditions, there was no significant difference in the maximum Von Mises stress of the T12 upper endplate and lower endplate between models. Under all loading conditions, there was no significant difference in the maximum Von Mises stress of T11/12 and T12/L1 intervertebral discs among the models. (4) When the displacement was 3.5 mm, the load of the central separation model was the minimum, which was 40 N. The load of the central integration and anterior separation models was 50 N. The load of the uneven separation model was the largest, which was twice that of the central separation model. (5) The results show that the uneven cement separation significantly increases cement stress, so percutaneous vertebral augmentation should be performed with the adequate and symmetrical distribution of cement in the vertebral fracture area and appropriately increased in the area of contact between the cement and cancellous bone interface.  Figures and Tables | References | Related Articles | Metrics

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Preparation of calcium silicate microspheres loaded with epigallocatechin gallate and investigation on its antibacterial performance Fan Haomei, Xiao Dongqin, Shi Feng, Luo Xuwei, Wei Jianlin, Zhuang Huadi, Liu Jinhui, Zhao Juhua 2023, 27 (30):  4769-4775.  doi: 10.12307/2023.553 Abstract ( 275 )   PDF (1580KB) ( 83 )   Save BACKGROUND: The main active component of tea polyphenols is epigallocatechin gallate, which has various biological functions such as antioxidation, antibacteria, anti-apoptosis, and anti-inflammation. To realize the controllable release of tea polyphenols and improve their bioavailability, it is urgent to develop bioactive carriers for tea polyphenols.  OBJECTIVE: To prepare microspheres loaded with high-efficiency epigallocatechin gallate, and measure its antibacterial performance and biocompatibility.  METHODS: Calcium silicate microspheres were prepared by chemical precipitation method. X-ray photoelectron spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, surface area measurement and laser particle size analyzer were used to characterize the performance of the microspheres. The two kinds of microspheres were immersed in epigallocatechin gallate solution respectively to prepare calcium silicate microspheres and silica microspheres loaded with epigallocatechin gallate (named as CSM-EGCG and SM-EGCG, respectively). The drug loading rate and encapsulation rate of the microspheres, as well as the release of epigallocatechin gallate in vitro were detected. The unloaded calcium silicate microspheres, silica microspheres, CSM-EGCG and SM-EGCG were co-cultured with Staphylococcus aureus and Escherichia coli, respectively, to detect the antibacterial capacity. The above four kinds of microspheres were co-cultured with human skin fibroblasts respectively, and the cell viability was evaluated by CCK-8 assay.  RESULTS AND CONCLUSION: (1) The characterization experiment results showed that the prepared calcium silicate spheres and silica spheres were mesoporous microspheres, and the specific surface area, total pore volume and average pore size of calcium silicate spheres were larger than those of silica spheres. (2) The encapsulation rate and drug loading rate of CSM-EGCG were (72.0±0.5)% and (58.4±0.4)%, respectively. The encapsulation rate and drug loading rate of SM-EGCG were (41.6±0.7)% and (45.0±1.3)%, respectively. CSM-EGCG microspheres had better drug loading capacity than SM-EGCG microspheres, and the drug release time in vitro lasted for more than 19 days, and the cumulative release reached (88.1±3.0)%. (3) Silica microspheres had no antibacterial activity. The antibacterial rates of calcium silicate microspheres, SM-EGCG, and CSM-EGCG against Staphylococcus aureus were (28.0±4.2)%, (63.9±1.0)%, and (95.6±0.5)%, respectively. The antibacterial rates against Escherichia coli were (27.5±7.0)%, (51.9±1.4)%, and (93.4±1.0)%, respectively. (4) CCK-8 assay results showed that the calcium silicate spheres and CSM-EGCG had good cell biocompatibility and showed enhanced proliferation of human skin fibroblasts. (5) These results verified that the epigallocatechin gallate-loaded calcium silicate spheres have good antibacterial activity and cytocompatibility. Figures and Tables | References | Related Articles | Metrics

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Preparation of hierarchical porous cartilage composite scaffolds loaded with stromal cell-derived factor-1 using low-temperature deposition 3D printing Wu Jiang, Yin Han, Yan Zineng, Tian Guangzhao, Ding Zhengang, Yuan Xun, Fu Liwei, Tian Zhuang, Sui Xiang, Liu Shuyun, Guo Quanyi 2023, 27 (30):  4776-4782.  doi: 10.12307/2023.543 Abstract ( 281 )   PDF (2216KB) ( 78 )   Save BACKGROUND: The treatment regimen based on the promotion of stem cell recruitment to achieve in situ regeneration and repair of cartilage damage is a new strategy in cartilage tissue engineering. OBJECTIVE: To prepare hierarchical porous cartilage composite scaffolds loaded with stromal cell-derived factor-1 (SDF-1) using low-temperature deposition 3D printing. METHODS: The cartilage was decellularized by a chemical method. The bioink was prepared with the addition of SDF-1 to decellularized cartilage extracellular matrix homogenate. The graded porous extracellular matrix scaffolds were constructed using low-temperature deposition 3D printing. The microstructure of scaffolds was observed by scanning electron microscopy. The biocompatibility of the scaffolds was evaluated by CCK-8, live-dead cell staining, and ghost pen peptide cell skeleton staining. The in vitro sustained release of the scaffolds was tested, and the effects of the scaffolds on the migration of bone marrow mesenchymal stem cells were detected by Transwell assay.  RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that the printed extracellular matrix scaffolds had a hierarchical porous structure, with fibers staggered and interconnected between pores. (2) The CCK-8 results indicated that the prepared extracellular matrix scaffolds had no obvious cytotoxicity. Live-dead cell staining showed that bone marrow mesenchymal stem cells were able to grow well on the extracellular matrix scaffolds; ghost pen peptide cell skeleton staining showed that bone marrow mesenchymal stem cells were able to spread well on the extracellular matrix scaffold in a shuttle shape. (3) The extracellular matrix scaffold had a good sustained release property. SDF-1 was released rapidly during the initial 7 days, with a cumulative release rate of about 60%. The release rate of SDF-1 gradually slowed down during 1-4 weeks, and the release pattern during 4-6 weeks was similar to the zero-order release kinetics, and the cumulative release rate reached about 80% at 42 days, and there was still a trend of slow release. (4) The results of Transwell migration assay showed that SDF-1 improved the ability of extracellular matrix scaffolds to recruit stem cells. (5) These findings suggest that SDF-1 can improve the ability of low-temperature deposited 3D printed extracellular matrix scaffolds to recruit bone marrow mesenchymal stem cells. Figures and Tables | References | Related Articles | Metrics

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Effect of silane coupling agent composite graphene oxide coating on biological behavior of Schwann cells on pure titanium Xu Xingxing, Wen Chaoju, Li Ying, Meng Maohua, Wang Qinying, Chen Jingqiao, Dong Qiang 2023, 27 (30):  4783-4789.  doi: 10.12307/2023.555 Abstract ( 305 )   PDF (1339KB) ( 143 )   Save BACKGROUND: The study of implant surface treatment pays more attention to whether it can improve the efficiency of implant osseointegration, while the study of oral implant bone perception function is relatively less.  OBJECTIVE: To investigate the effect of silane coupling agent covalently bonded graphene oxide coating on the biological behavior of Schwann cells in vitro.  METHODS: Different mass concentrations of graphene oxide coating (0.25, 0.5, 0.75, and 1.0 mg/mL, named as 0.25-Ti-APTES-GO group, 0.5-Ti-APTES-GO group, 0.75-Ti-APTES-GO, and 1.0-Ti-APTES-GO group) were prepared on the surface of TA4 titanium sheet by covalent bonding of amino groups of silane coupling agent. The microstructure, composition and contact angle of the coating were characterized by scanning electron microscopy, Raman spectroscopy and contact instrument. Rat Schwann cells were cultured on smooth titanium sheet, silane coupling modified titanium sheet and graphene oxide coating modified titanium sheet with different mass concentrations. The proliferation activity of Schwann cells in each group was detected by CCK-8 cell proliferation assay. RT-qPCR and western blot assay were used to detect the ability of Schwann cells to secrete nerve growth factor and glial cell-derived neurotrophic factor on titanium sheets.  RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that silane coupling agent composite with different concentrations of graphene oxide coatings were cloudy, and high concentration of graphene oxide coating appeared more dense cloudy protrusions. (2) Compared with the smooth titanium sheet group, the contact angle of the silane coupling agent film titanium group was smaller (P < 0.05). The contact angle of silane coupling agent composite graphene oxide coating became small with the increase of graphene oxide concentration. Among them, the contact angle of 0.75-Ti-APTES-GO group and 1.0-Ti-APTES-GO group was smaller than that of smooth titanium sheet group (P < 0.05). (3) In the CCK-8 cell proliferation assay, compared with the smooth titanium sheet group, there was no significant change in cell proliferation in silane coupling modified titanium sheet group, 0.25-Ti-APTES-GO group and 0.5-Ti-APTES-GO group (P > 0.05). Cell proliferation was inhibited in 0.75-Ti-APTES-GO group and 1.0-Ti-APTES-GO group (P < 0.05), so 0.25-Ti-APTES-GO group and 0.5-Ti-APTES-GO group were selected for subsequent experiments. (4) RT-qPCR exhibited that the expression of nerve growth factor mRNA in 0.5-Ti-APTES-GO group was higher than that in the other three groups (P < 0.05). The expression of glial cell-derived neurotrophic factor mRNA in 0.25-Ti-APTES-GO group was lower than that in other three groups (P < 0.05). The expression of glial cell-derived neurotrophic factor mRNA in 0.5-Ti-APTES-GO group was higher than that in smooth titanium sheet group and silane coupling modified titanium sheet group (P < 0.05). (5) Western blot assay exhibited that the expression level of nerve growth factor protein in the 0.5-Ti-APTES-GO group was higher than that in the smooth titanium sheet group and 0.25-Ti-APTES-GO group (P < 0.05), and the expression level of glial cell-derived neurotrophic factor protein was higher than that in the other three groups (P < 0.05). (6) The results indicated that silane coupling agent combined with 0.5 mg/mL graphene oxide coating had good biocompatibility and could promote the expression of Schwann cell nerve growth factor and glial cell-derived neurotrophic factor on pure titanium surface. Figures and Tables | References | Related Articles | Metrics

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Preparation and release property of norfloxacin sustained-release microspheres Yuan Jialu, Liu Mei, Qin Xiaolong, Qiu Yang, Li Jing 2023, 27 (30):  4790-4795.  doi: 10.12307/2023.509 Abstract ( 336 )   PDF (1259KB) ( 161 )   Save BACKGROUND: Norfloxacin is widely used in clinical practice. When it is used as the sustained-release microspheres, it can play a role in a long time, largely improve the bioavailability and elevate the compliance of patient’s medication, and also can decrease the adverse reaction, discomfort and medication dosage during the treatment period. It has important research significance and application value.  OBJECTIVE: To prepare norfloxacin-loaded microspheres and investigate and analyze its preparation conditions, release properties and structure with chitosan, nano-SiO2 and sodium alginate as the raw materials.  METHODS: Norfloxacin microspheres were prepared by extrusion-exogenous gel method. The effects of norfloxacin concentration, m(SiO2):m(norfloxacin) and crosslinking time on the encapsulation rate of norfloxacin microspheres were investigated by single factor experiment. The optimal preparation conditions were determined and two types of norfloxacin sustained release microspheres, calcium alginate/chitosan and SiO2-calcium alginate/chitosan, were prepared under the optimal preparation conditions. The microspheres were characterized and released in vitro.   RESULTS AND CONCLUSION: (1) The single factor experiment results showed that the encapsulation rate of microspheres was better when the concentration of norfloxacin was 1.5 g/L, the concentration of m(SiO2):m(norfloxacin) was 4:10, and the crosslinking time was 20 minutes. (2) Through the characterization of the microspheres by Fourier Transform Infrared Spectroscopy, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis, it can be concluded that the microspheres prepared under the above conditions tended to be amorphous materials, with uniform appearance size and regular shape, and SiO2 had good compatibility with calcium alginate and chitosan, forming a new complex. The addition of SiO2 had no effect on the morphology of the microspheres. The thermal stability of SiO2 microspheres was better. (3) The sustained release performance of the prepared microspheres showed that the microspheres had a certain sustained release effect, no sudden release phenomenon occurred during the release, and the addition of SiO2 microspheres had better salt resistance.   Figures and Tables | References | Related Articles | Metrics

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Design and three-dimensional finite element analysis of 3D printed individualized titanium mesh with a bionic porous spider web-shaped structure Zhang Liang, Han Zekui, Zang Yixin, Han Zhenjia, Wang Xinyu 2023, 27 (30):  4796-4801.  doi: 10.12307/2023.544 Abstract ( 363 )   PDF (2104KB) ( 82 )   Save BACKGROUND: The spider web-shaped structure has an inherent capability to dissipate energy to withstand large concentrated loads, which is applied to the design of 3D printed individualized titanium mesh to reduce local fractures caused by stress concentration.  OBJECTIVE: To explore the design method of a novel 3D printed individualized titanium mesh with a bionic porous spider web-shaped structure and analyze the biomechanical characteristics of the titanium mesh using 3D finite element method. METHODS: The CBCT, Mimics, Geomagic Wrap, 3-matic Research and ANSYS Workbench softwares were used to establish individualized titanium mesh finite element models with bionic porous spider web-shaped, circular pore, square pore, and hexagonal pore structures with a thickness of 0.3 mm, respectively. A load of 100 N was applied to the titanium mesh corresponding to the alveolar crest for mechanical finite element analysis. RESULTS AND CONCLUSION: (1) The maximum deformation values of the individualized titanium mesh for square pore, circular pore, hexagonal pore structures, and bionic porous spider web-shaped structures were 0.064, 0.103, 0.107, and 0.070 mm, respectively, and the maximum equivalent stress values were 1 633.5, 1 611.3, 2 131.2, and 1 104.8 MPa, respectively. (2) The stress distribution of retaining screws in the titanium mesh in each group was similar, mainly concentrated in the contact area between the screw neck and the titanium mesh, and the maximum equivalent stress values of the retaining screws in the square pore, circular pore, hexagonal pore structures, and bionic porous spider web-shaped structure groups were 149.13, 200.32, 178.73, and 163.30 MPa, respectively, and the stress of retaining screws in each group was within the safe range. (3) These findings suggest that the individualized titanium mesh with a bionic porous spider web-shaped structure can well disperse the stress of the titanium mesh and reduce stress concentration. In addition, 0.3 mm thickness of the individualized titanium mesh with a bionic porous spider web-shaped structure meet the requirements of mechanical strength for reconstruction of large-area jaw defects.  Figures and Tables | References | Related Articles | Metrics

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Effects of hydrogels loaded with hepatocyte growth factor on myocardial infarction Wang Nanfeng, Shen Shengmei, Zhang Peisheng, Teng Wei 2023, 27 (30):  4802-4808.  doi: 10.12307/2023.547 Abstract ( 237 )   PDF (1221KB) ( 57 )   Save BACKGROUND: Hepatocyte growth factor (HGF) has been shown to reduce cardiomyocyte apoptosis and improve cardiac function after myocardial infarction in diabetic rats. Intravenous injection or gene transfection is common methods of drug delivery in many previous studies; however, a sustained release system was used in very few studies. OBJECTIVE: To investigate the effects of intramyocardial injection of hydrogels loaded with HGF on myocardial infarction. METHODS: The sodium glycerophosphate/chitosan/sodium alginate/HGF composite hydrogel was prepared, and the compatibility of the hydrogel with cardiomyocytes and the release characteristics of growth factors in vitro were detected. A total of 54 male Sprage-Dawley rats (3 months old) were used for the establishment of myocardial infarction models by ligating the left anterior descending branch of the coronary artery and equally and randomly divided into three groups: untreated (multi-point injection of PBS at the edge of myocardial infarction), hydrogel without HGF (multi-point injection of sodium glycerophosphate/chitosan/sodium alginate composite hydrogel at the edge of myocardial infarction), and hydrogel with HGF (multi-point injection of sodium glycerophosphate/chitosan/sodium alginate/HGF composite hydrogel at the edge of myocardial infarction) groups. RESULTS AND CONCLUSION: (1) Live-dead cell staining and CCK-8 assay showed that sodium glycerophosphate/chitosan/sodium alginate/hepatocyte growth factor hydrogel had good cytocompatibility and promoted the proliferation and survival of cardiomyocytes and could sustainably release HGF for more than 42 days. (2) The left ventricular volume and left ventricular volume at the end of diastole were significantly decreased in the hydrogel with HGF groups (P < 0.05), while the left ventricular ejection fraction and left ventricular short-axis shortening rate were significantly increased (P < 0.05) compared with the other two groups at 7, 14, 35 days after surgery. (3) Hemotoxylin-eosin and Masson stainings showed that the myocardial histopathology of rats in both treatment groups was significantly improved compared with the untreated group, and the most obvious improvement was found in the hydrogel with HGF group at 35 days after surgery. (4) TUNEL staining and α-smooth muscle actin immunofluorescence staining showed that the number of cardiomyocyte apoptosis was significantly decreased, while microvessel density was significantly increased in the hydrogel with HGF group compared with the other groups (P < 0.05). (5) These findings exhibit that intramyocardial injection of sodium glycerophosphate/chitosan/sodium alginate/hepatocyte growth factor composite hydrogel can inhibit cardiomyocyte apoptosis and myocardial fibrosis, promote revascularization, and delay left ventricular remodeling, improving cardiac function. Figures and Tables | References | Related Articles | Metrics

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Repair effect of different hydroxyapatite/beta-tricalcium phosphate coated scaffolds on bone defects Song Meiling, Li Zhengyu, Ai Zizheng, Li Jingna, Zeng Qingfeng, Han Qianqian, Dong Xieping 2023, 27 (30):  4809-4816.  doi: 10.12307/2023.507 Abstract ( 710 )   PDF (1797KB) ( 175 )   Save BACKGROUND: Hydroxyapatite/β-tricalcium phosphate biphasic calcium phosphate ceramics have good biocompatibility and osteoconductivity. They can be used as a coating material for supercritical bone defect repair, but the optimal mass ratio of hydroxyapatite/β-tricalcium phosphate coating has not been reported.  OBJECTIVE: Porous bioceramic scaffolds with different ratios of hydroxyapatite/β-tricalcium phosphate coating were implanted into the supercritical bone defect site of rabbit radius to assess its repairing effects in order to obtain the best coating ratio. METHODS: Hydroxyapatite porous bioceramic scaffolds were prepared by 3D printing technology, and coated with different mass ratios of hydroxyapatite/β-tricalcium phosphate (mass ratio: 3:7, 5:5, 7:3, respectively) on their surfaces. Cytotoxicity, porosity, mechanical strength, coating thickness, and other parameters were tested. The 15.0 mm rabbit radial supercritical bone defects were established in the right forelimbs of 36 New Zealand white rabbits. They were randomly divided into four groups (n=9). In the blank group, no material was implanted. In the 3:7 coating group, 5:5 coating group, and 7:3 coating group, hydroxyapatite porous bioceramic scaffolds were implanted with corresponding mass ratio coatings. X-ray, Micro-CT, Van-Gieson staining, hematoxylin-eosin staining, and immunohistochemistry for type I collagen were performed at 4, 8, and 12 weeks after operation.  RESULTS AND CONCLUSION: (1) The scaffold cytotoxicity of 3:7, 5:5, and 7:3 coating was grade 0. The coating thickness was (75.2±0.54) μm, and the porosity was (54.02±5.17)%, (53.28±5.05)%, and (52.82±4.55)%, respectively. The compressive strength was (11.15±0.72), (11.18±0.78), and (10.24±0.70) MPa, respectively. (2) The X-ray and Micro-CT results showed that with the increase of time, the bone defects in each group were repaired to different degrees. The 3:7 coating group had the best bone defect repair effect at 12 weeks after the operation. The volume of bone ingrowth inside the group of materials and the volume of new bone on the outer surface of the materials were the most. (3) The results of Van-Gieson staining and hematoxylin-eosin staining showed that new bone was formed in the bone defect area and inside the scaffold, and the new bone tissue was the most and the new bone structure was the densest one in the 3:7 coating group at 12 weeks after operation. The results of immunohistochemical analysis showed that the expression of type I collagen in the 3:7 coating group was higher than that in the other two groups at 12 weeks after surgery. (4) The results showed that the 3:7 coating group had the best repair effect on the supercritical bone defects of the rabbits, and the optimal mass ratio of hydroxyapatite/β-tricalcium phosphate was 3:7.  Figures and Tables | References | Related Articles | Metrics

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Optimization of specific adsorption conditions for hemoglobin in blood by graphite-phase carbon nitride Lu Tian, Tao Yuan, Yang Tuo, Sun Lulu, Pei Xinyang, Zhao Liang, Li Wenbin 2023, 27 (30):  4817-4823.  doi: 10.12307/2023.546 Abstract ( 306 )   PDF (1980KB) ( 80 )   Save BACKGROUND: Currently, there has been no effective strategy for prolonging the 6-hour safe time limit of cardiopulmonary bypass mainly due to the accumulation of free hemoglobin. OBJECTIVE: To investigate the optimum conditions and the highest adsorption efficiency of graphite-phase carbon nitride (g-C3N4) adsorbing free hemoglobin.  METHODS: Different concentrations of hemoglobin solutions were prepared to study the adsorption capacity of g-C3N4 for hemoglobin, and then the adsorption efficiency of characteristic proteins (albumin, hemoglobin, cytochrome C) in whole blood at different pH values was explored. Based on clinical application conditions, the influences of pH, g-C3N4: blood sample (mg/mL), reaction temperature (°C) and reaction time (minite) on adsorption efficiency were investigated. Using the model created by the response surface analysis software Design-Expert.8.0.6, pH (A), g-C3N4: blood sample (mg/mL) (B), reaction time (C), and reaction temperature (D) were set as independent variables, and the adsorption efficiency of free hemoglobin in whole blood as dependent variables, the experiment with four factors and three levels was designed. According to the single factor experiment results, the zero level and fluctuation zone of three factors were selected, and the absorbance was measured by ultraviolet spectrophotometer to calculate the content of free hemoglobin before and after adsorption, and then the adsorption efficiency was calculated. Finally, the specific adsorption effect of g-C3N4 on hemoglobin in whole blood was verified by electrophoresis.  RESULTS AND CONCLUSION: (1) With the increase of hemoglobin concentration in blood, the adsorption capacity of g-C3N4 to free hemoglobin increased gradually, but did not satisfy the linear relationship. (2) Single factor experiment showed that when the pH was 8.0, the adsorption efficiency of free hemoglobin in whole blood was 93.5%, and the adsorption of other proteins was few. When the pH value increases further, the adsorption efficiency for free hemoglobin initially remains stable and then gradually decreases. With the increase of g-C3N4: blood sample ratio, reaction time and reaction temperature, the adsorption efficiency of free hemoglobin in whole blood increased gradually. (3) The multiple regression equation of this experiment was calculated by Design-Expert.8.0.6 software, and the optimal action values of the four factors were obtained. The highest adsorption efficiency of free hemoglobin in whole blood was obtained by software analysis under the following experimental conditions: pH=7.5, in g-C3N4: blood sample (mg/mL) was 6.00:1, reaction temperature was 36.5 °C, reaction time was 60 minutes, and the adsorption efficiency of free hemoglobin in whole blood was 54.34%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that g-C3N4 achieved specific adsorption of hemoglobin in whole blood under the optimum adsorption conditions. (4) These results indicate that g-C3N4 can specifically adsorb free hemoglobin and improve the adsorption efficiency under the optimal adsorption conditions, which is expected to be a new biomedical material and further promote the development of tissue engineering materials. Figures and Tables | References | Related Articles | Metrics

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Three-dimensional finite element analysis of different restorative methods for ultrashort implants Reyila·Kuerban, Xiaheida·Yilaerjiang, Chen Xin, Zilala·Julaiti, Baibujiafu·Yellisi, Nijati·Turson 2023, 27 (30):  4824-4829.  doi: 10.12307/2023.833 Abstract ( 279 )   PDF (1322KB) ( 49 )   Save BACKGROUND: During the restoration of ultrashort implants, different restorative methods and occlusal forces in different directions affect the internal structure of the implant and the distribution of stresses at the implant-bone interface, which determine the longevity of the implant and the stability of the surrounding bone level. OBJECTIVE: To analyze the effects of different restorative methods on the implant and surrounding bone tissue after implantation of ultrashort implants in the first and second molar areas with severe alveolar bone resorption (insufficient distance from the mandibular nerve).   METHODS: Cone beam CT images of a patient with implant restoration in the first and second mandibular molar areas were selected from Department of Stomatology, Second Affiliated Hospital of Xinjiang Medical University. This patient met the Class II bone quality classification of the jaw. Two Φ5 mm×5 mm ultra-short implants were used. Based on cone beam CT imaging data, a three-dimensional model of the mandible was established. A joint-crown restoration model or two single-crown restoration models for the implants in the lower first and second molar areas were established. A force perpendicular to the long axis of the dentition with the long axis of the dentition was applied in the first and second molar areas at 45° obliquely (the points of action were located on the fossa of the dentition and buccal occlusal half surface, respectively) with a loading force of 150 N on the points of the first and second molars respectively. The stress distribution in the internal structures and bone tissues of the implant was analyzed using finite element software.  RESULTS AND CONCLUSION: (1) When the vertical load was applied, using single-crown restoration, the stress of the crown was concentrated at the connection between the inner wall of the crown and the abutment, and the peak stress of each component was concentrated on the central screw. When using the joint-crown restoration, the peak stress of the crown was concentrated near the gingival margin of the joint-crown connector, and the peak stress of each component was concentrated on the joint crown. The peak stress of each component of single-crown restoration was higher than that of joint-crown restoration, and the peak stress of bone tissue was also significantly higher than that of joint-crown restoration. (2) When the oblique load was applied, using single-crown restoration, the stress concentration area of the crown was located at the connection between the inner wall of the crown and the abutment, and the peak stress of each component was concentrated on the central screw. When using the joint-crown restoration, the peak stress of the crown was concentrated near the gingival margin of the joint-crown connector, and the stress distribution of the crown, central screw, abutment, and ultrashort implant was relatively concentrated. The peak stress of a single-crown prosthesis and its components was significantly lower than that of the joint-crown prosthesis, and the peak stress of the central screw, ultrashort implant and abutment was larger when the joint-crown prosthesis was performed. (3) There was no significant difference in stress distribution between the two kinds of loads when the single-crown restoration was used. When using the joint-crown restoration, the stress of the implant prosthesis was mainly distributed on the connector in the middle of the joint crown after applying two kinds of loads, and the peak stress of each component was small and uniform when applying the vertical load. (4) If only the bone stress distribution of the ultrashort implant is considered, two different repair methods can be selected. If the long-term retention rate of the ultrashort implant is considered, the single-crown restoration can be selected to avoid mechanical complications. Figures and Tables | References | Related Articles | Metrics

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Effect of nano-hydroxyapatite/polyamide-66 intervertebral fusion cage shape on the efficacy of anterior cervical discectomy and fusion Xu Shicai, Ma Fei, Tang Chao, Liao Yehui, Tang Qiang, Chen Shiyu, Li Yang, Zhou Jiajun, Wang Qing, Zhong Dejun 2023, 27 (30):  4830-4835.  doi: 10.12307/2023.832 Abstract ( 282 )   PDF (1421KB) ( 105 )   Save BACKGROUND: Current studies have reported that interbody fusion materials are one of the factors affecting the postoperative efficacy of patients with cervical spondylosis, but there are few reports on the postoperative efficacy of the same materials with different geometric shapes in patients with cervical spondylosis.  OBJECTIVE: To observe the effect of nano-hydroxyapatite/polyamide-66 intervertebral fusion cage shape on the efficacy of anterior cervical discectomy and fusion.  METHODS: Clinical data of 122 patients with single-segment cervical spondylosis who were admitted to the Affiliated Hospital of Southwest Medical University from January 2016 to June 2020 were retrospectively analyzed. They were divided into a columnar group (n=60) and a horseshoe group (n=62) according to the shape of nano-hydroxyapatite/polyamide-66 intervertebral fusion (cage). The visual analog scale score, neck disability index, fusion segmental height, C2-7 angle, segmental sagittal alignment, and intervertebral fusion were compared between the two groups before and after the operation.  RESULTS AND CONCLUSION: (1) Compared with that before operation, the visual analog scale scores of the two groups at 2 days, 1 year and the last follow-up decreased (P < 0.05), and the influence of neck disability index at 6 months and the last follow-up decreased (P < 0.05). There was no significant difference between the two groups in visual analog scale score and neck disability index before and after surgery (P > 0.05). (2) The fusion rate of the horseshoe group at 6 and 12 months after surgery was significantly higher than that of the columnar group (P < 0.05). The modified Brantigan score of the horseshoe group at 6 and 12 months after operation was lower than that of the columnar group (P < 0.05). (3) The extent of cage subsidence in patients in the horseshoe group was lower than that in the columnar group (P < 0.05). There were no significant differences in the extent of cage subsidence between the two groups (P > 0.05). (4) There were no significant differences in C2-7 angle, segmental sagittal alignment, and fusion segmental height between the two groups before and after surgery (P > 0.05). (5) The results show that the horseshoe and columnar nano-hydroxyapatite/polyamide-66 intervertebral fusion cage can obtain good efficacy in the single-segment anterior cervical discectomy and fusion, but the horseshoe nano-hydroxyapatite/polyamide-66 intervertebral fusion cage can improve the early fusion rate and reduce the subsidence of the intervertebral space.  Figures and Tables | References | Related Articles | Metrics

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Degradation and drug release behavior of sirolimus-poly(trimethylene carbonate) modified magnesium alloy Zhao Zheng, Ding Wenfei, Shao Shuxin, Wang Jinyan, Jian Xigao 2023, 27 (30):  4836-4843.  doi: 10.12307/2023.558 Abstract ( 295 )   PDF (1877KB) ( 69 )   Save BACKGROUND: The control of degradation and drug release of magnesium alloy stents is an urgent issue. Biodegradable drug-polymer coatings as promising modification strategies have aroused wide attraction.  OBJECTIVE: To investigate the effect of drug-loaded biodegradable polymer coating on magnesium alloy degradation and the effect of magnesium alloy degradation on drug release of the drug-loaded biodegradable polymer coating.   METHODS: Different drug-polymer solutions, solution S1, were prepared: sirolimus 0.01 g, poly(trimethylene carbonate) 0.005 g, dichloromethane 1 mL; solution S2: sirolimus 0.01 g, poly(trimethylene carbonate) 0.01 g, dichloromethane 1 mL; S3: sirolimus 0.01 g, poly(trimethylene carbonate) 0.02 g, dichloromethane 1 mL; S2-1: sirolimus 0.01 g, poly(trimethylene carbonate) 0.01 g, 0.001 g polyethylene glycol 400, dichloromethane 1 mL; S2-2: sirolimus 0.01 g, poly(trimethylene carbonate) 0.01 g, 0.002 g polyethylene glycol 400, dichloromethane 1 mL. The coating was prepared by coating the surface of AZ31 magnesium alloy with five kinds of drug-polymer solutions. The difference in drug release behavior of the coating on the magnesium alloy substrate and the influence of each coating on the corrosion ability of magnesium alloy were compared. The influence of the substrate on sirolimus-poly(trimethylene carbonate) coating and in vitro cytocompatibility and hemocompatibility of the modified magnesium alloys were investigated.  RESULTS AND CONCLUSION: (1) The modification of the sirolimus-poly(trimethylene carbonate) coatings could significantly enhance the corrosion resistance of the magnesium alloy. With the release of the drug, the anti-corrosion ability of the coatings gradually decreased due to the water channel formation of the coatings. The alkaline microenvironment caused by the magnesium alloy degradation slightly accelerated the release of sirolimus in the later immersion. The increased proportion of sirolimus in the coating or the increased proportion of polyethylene glycol in the coating increased the drug release rate, but decreased the anti-corrosion ability. The above results indicate that there is a two-way promotion effect between the degradation of magnesium alloy and the degradation of drug coating. That is, the degradation of magnesium alloy promotes the degradation of drug coating, and the pores caused by the degradation of drug coating in turn further accelerate the degradation of magnesium alloy. (2) The five kinds of drug coatings can effectively inhibit the proliferation and adhesion of human vascular endothelial cells and human vascular smooth muscle cells, neither causing the hemolytic reaction, nor affecting the endogenous and exogenous coagulation mechanism (the effect of different coating parameters has a small difference). Figures and Tables | References | Related Articles | Metrics

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Screening and verification of differentially expressed genes in inflammatory tissues with peri-implantitis Wei Yuxing, Dong Hao, Wei Huiping, Xie Cheng, Tuo Yangjuan, Qin Hao, Cao Yong 2023, 27 (30):  4844-4849.  doi: 10.12307/2023.802 Abstract ( 999 )   PDF (2265KB) ( 133 )   Save BACKGROUND: Peri-implantitis seriously affects the success of dental implant restorations. There is still no effective cure and its pathogenesis has not yet been elucidated.  OBJECTIVE: To find key differentially expressed genes related to the occurrence of peri-implantitis and experimentally verify them.  METHODS: Differentially expressed genes between the peri-implantitis and the healthy gums were screened from the GEO database using bioinformatics technology and were analyzed by enrichment analysis. A protein interaction network was constructed using the String database. Key genes were screened by Cytoscape software. Expression of key gene C3AR1 was validated using RT-PCR and immunohistochemistry. The expression level of C3AR1 mRNA in RAW264.7 cells after osteoclast differentiation was detected by RT-PCR.  RESULTS AND CONCLUSION: (1) The gene data of peri-implantitis and the healthy gums in the GSE33774 data set were analyzed for differences. A total of 50 differentially expressed genes were obtained, including 33 upregulated genes and 17 downregulated genes. GO functional enrichment and KEGG pathway enrichment analysis showed that differentially expressed genes mainly played a role in immune receptor activity, C-C chemokine receptor activity, and the signaling pathway of osteoclast differentiation. (2) Six key target genes were identified based on the protein interaction network, including C3AR1, CD14, TLR4, CCR1, CYBB, and FCGR2A. The results of RT-PCR and immunohistochemistry experiments showed that the expression of C3AR1 at mRNA and protein levels was significantly increased in peri-implantitis tissue. Moreover, C3AR1 was upregulated after osteoclastic differentiation of macrophages. (3) It is concluded that C3AR1 showed high expression in peri-implantitis, which may be a key gene for bone destruction in peri-implantitis. Figures and Tables | References | Related Articles | Metrics

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Effects of different taping methods on knee joint stress during drop jump landing Xiang Furong, Tang Shengxin, Ou Lizhen, Lin Xikai, Chen Jian 2023, 27 (30):  4850-4855.  doi: 10.12307/2023.810 Abstract ( 432 )   PDF (1228KB) ( 164 )   Save BACKGROUND: As an effective protection method, taping has been widely used; however, the influence of different taping methods on the internal stress of the knee joint is not clear.  OBJECTIVE: To analyze the effect of different kinds of taping on knee kinematics, dynamics and the stress distribution of cartilage, meniscus and anterior cruciate ligament during prevention of drop jump landing in female basketball players. METHODS: (1) Ten female basketball majors from Wuhan Sports University were recruited, with a height of (166.60±1.64) cm, a body mass of (57.50±2.87) kg and a mean age of (22.40±1.77) years. The knee joint kinematics and ground reaction forces data were collected in participants without taping, with kinesio taping and elastic adhesive taping during drop jump landing. (2) The stress distribution of knee joint model was analyzed, which was based on the three-dimensional finite element model of the knee joint, the kinematic data of knee joint at peak vertical ground reaction force as the boundary condition and the resultant force in the long axis direction of the femur as the load. RESULTS AND CONCLUSION: (1) Drop jump landing data exhibited that knee valgus angles in non-taping and kinesio taping groups were larger than that in the elastic adhesive taping group when hitting the ground (P < 0.05). The knee valgus angles were larger in the non-taping group than that in the kinesio taping and elastic adhesive taping groups at the peak vertical ground reaction force (P < 0.05). The knee valgus angles were larger in the non-taping group than that in the kinesio taping and elastic adhesive taping groups in the buffering period (P < 0.05). The peak knee varus angle of non-taping group was smaller than that in the kinesio taping and elastic adhesive taping groups in the buffering period (P < 0.05). The peak internal rotation angle of the knee joint was larger in the non-taping and kinesio taping groups than that in the elastic adhesive taping group (P < 0.05). (2) Finite element model analysis results displayed that stress concentration was located in the middle of lateral condyle of femoral cartilage and lateral tibial cartilage, the medial margin of anterior horn of lateral meniscus in non-taping group. The middle of lateral condyle of femoral cartilage in the kinesio taping group, medial condyle of femoral cartilage in the elastic adhesive taping group, medial lateral part of medial tibial cartilage and medial margin of medial meniscus body in the kinesio taping and elastic adhesive taping groups were the stress concentration sites. (3) These results exhibited that the kinesio taping and elastic adhesive taping can reduce the sport mode of the frontal plane of the knee joint during landing buffering and decrease the stress on the lateral cartilage of the knee joint, the meniscus, and the femoral insertion of the anterior cruciate ligament. Furthermore, the elastic adhesive taping has a certain effect on promoting the horizontal internal rotation angle of knee joint. People with poor control of the frontal plane of the joint can use taping to improve the dynamic control of the knee joint during landing buffering and prevent the knee joint from injury. Figures and Tables | References | Related Articles | Metrics

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Application of decellularized extracellular matrix composite scaffolds in tissue regeneration Yang Shun, Zhao Mingyue, Tu Xiling, Gao Li, Yang Kun, Liu Qi 2023, 27 (30):  4856-4861.  doi: 10.12307/2023.806 Abstract ( 335 )   PDF (827KB) ( 95 )   Save BACKGROUND: Current decellularization methods inevitably cause damage to decellularized extracellular matrix scaffolds. To better exploit their advantages as tissue engineering scaffolds, it is particularly important to modify decellularized extracellular matrix scaffolds to improve their performance. OBJECTIVE: To review the application of decellularized extracellular matrix composite scaffolds in tissue regeneration.  METHODS: Keywords “decellularized extracellular matrix, tissue engineering, crosslinking, electrospun nanofibers, 3D bioprinting technology, tissue regeneration” were searched on PubMed, WanFang and CNKI databases. The language of the literature was limited to Chinese and English, and the retrieval time was from 2009 to 2022.  A total of more than 142 articles were retrieved, and 79 articles were finally included for review. RESULTS AND CONCLUSION: The process of removing cells from tissues or organs by chemical, physical and biological methods inevitably leads to ultrastructural damage of decellularized extracellular matrix scaffolds, as well as adverse factors such as poor mechanical properties, and uncontrolled degradation. The composite scaffold can be modified by cross-linking, electrospinning, three-dimensional bioprinting, nanoparticles, methoxy polyethylene glycol, and growth factor, which can optimize the performance of decellularized extracellular matrix scaffold. Among them, three-dimensional bioprinting technology can print more stable and precise composite scaffolds from modified decellularized extracellular matrix bioprinks, showing a great potential for personalized and precise tissue regeneration. However, achieving functional and structural tissue regeneration and clinical transformation still needs to be explored and studied. Figures and Tables | References | Related Articles | Metrics

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Application of the nanovesicle delivery system in cardiovascular diseases Peng Fengli, Li Chaofu, Shi Bei 2023, 27 (30):  4862-4868.  doi: 10.12307/2023.470 Abstract ( 792 )   PDF (1210KB) ( 70 )   Save BACKGROUND: At present, the focus on cardiovascular disease treatment is mainly on precision treatment. As a natural nano delivery system, extracellular vesicles can deliver therapeutic drugs to the target location. In view of some characteristics of parent cells, it is expected to be used as an alternative therapy for cell therapy. OBJECTIVE: To summarize the research status and latest progress of extracellular nanovesicles delivery system in cardiovascular diseases. METHODS: The computer was used to search the related research of extracellular vesicles and use it as a nano-drug delivery system in databases such as CNKI and PubMed. Chinese and English key words were “extracellular vesicle, bionic vesicle, engineered vesicle, exosome, microvesicle, drug delivery, drug loading, nanopartical system, cardiovascular disease”. Finally, 83 articles were included for review and analysis.  RESULTS AND CONCLUSION: (1) Extracellular vesicle is a kind of nanovesicles, which can transfer bioactive molecules from donor cells to recipient cells through membrane fusion, receptor ligand interaction mode, endocytosis or phagocytosis and other mechanisms. (2) Compared with traditional nanomaterials, extracellular vesicles have the advantages of biocompatibility, biodegradability, low toxicity and low immunogenicity. They are of great research significance in nanomedicine. (3) In view of the characteristics that it can be quickly cleared by the peripheral circulating mononuclear macrophage system, the nanovesicle delivery system can be constructed by means of the change of the delivery content, the modification of the extracellular vesicle membrane, the fusion and the bioengineering modification of the extracellular vesicles, so that the extracellular vesicles can avoid epidemic clearance and improve the targeting. (4) Extracellular vesicles are considered as a potential substitute for cell therapy, and have also become a nanoplatform for drug releases. It can not only avoid the immune rejection of cell transplantation, but also increase the targeting of drugs and reduce the drug toxicity to other tissues and organs. (5) Direct drug loading into extracellular vesicles may not be able to efficiently deliver to the recipient cells, which may be due to the fact that extracellular vesicles are easily phagocytized by the peripheral circulating mononuclear macrophage system. However, the nanovesicle delivery system constructed by extracellular vesicles through certain means can achieve immune escape, thus achieving the role of targeted therapy, providing a new means for the precise treatment of cardiovascular diseases. (6) The nanovesicle delivery system has a controlled-release property, which has great prospects of improving the cardioprotective potential for drugs for patients with cardiac ischemic events. (7) How to successfully construct a nanovesicle delivery system through extracellular vesicles to effectively deliver therapeutic drugs to the heart has great research values. Figures and Tables | References | Related Articles | Metrics

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Ischemic preconditioning improves exercise performance: methods, applications and mechanisms Wang Zhou, Wu Ying 2023, 27 (30):  4869-4875.  doi: 10.12307/2023.595 Abstract ( 681 )   PDF (916KB) ( 90 )   Save BACKGROUND: The protective effect of ischemic preconditioning has been widely confirmed and applied in the medical field. However, there is no unified conclusion on the application method, intervention site, applied pressure, duration and repetition period in the field of sports. There are also some differences in the effect of different types of exercise performance among related studies. OBJECTIVE: To describe the research progress of ischemic preconditioning in improving exercise performance, and to provide the best method and theoretical support for the application of ischemic preconditioning in the field of sports. METHODS: Literature retrieval was carried out in CNKI, WanFang Data, VIP, Web of Science, EBSCO, PubMed and Cochrane databases. The keywords included “ischemic preconditioning, preconditioning, preconditioning, blood flow restriction” and “exercise, exercise performance” in Chinese as well as “remote conditioning, remote ischemic conditioning, transient limb ischemia, muscle ischemia, ischemic preconditioning” and “exercise performance, sport, exercise, athletes” in English. Finally, 69 articles were included for review. RESULTS AND CONCLUSION: (1) The intervention methods of ischemic preconditioning are divided into remote ischemic preconditioning and local ischemic preconditioning. The common application site is the upper arm or the junction of the middle and lower third of the thigh. Interventions can be performed on both sides simultaneously or alternately. The pressure is 220 mmHg (1 mmHg=0.133 kPa), and the duration of intervention is usually set to be 4×5 minutes. (2) Research on ischemic preconditioning in the field of sports science focuses on cycling, swimming, running and resistance training. Ischemic preconditioning significantly improves the performance of aerobic endurance, anaerobic endurance and strength endurance, but its effect on explosive power is still controversial. (3) The main function of ischemic preconditioning is to stimulate the endogenous protective mechanism of human body under stress conditions, promote the release of opioid, bradykinin, and adenosine, enhance mitochondrial biosynthesis, and inhibit fatigue signal transduction, thereby improving athletic performance. (4) At present, the mechanism by which ischemic preconditioning enhances exercise performance has not been thoroughly studied. It is suggested to further explore the possible mechanism of its positive effects and pay attention to whether it has negative effects, so as to provide a basis for the scientific and reasonable application of ischemic preconditioning in the future. Figures and Tables | References | Related Articles | Metrics

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Functional characteristics of three-dimensional biological scaffolds for repairing injured spinal cord Jiu Jingwei, Liu Haifeng, Wang Guishan, Li Dijun, Yan Lei, Zhao Bin, Wang Bin 2023, 27 (30):  4876-4882.  doi: 10.12307/2023.503 Abstract ( 488 )   PDF (984KB) ( 52 )   Save BACKGROUND: Spinal cord injury can result in irreversible tissue damage and persistent sensorimotor impairment. Treatment of spinal cord injury is a significant problem that has piqued clinical scientists’ interest. Biomimetic three-dimensional scaffolds have shown to be a viable option for nervous system repair. 3D biological scaffolds of various sizes and forms can be swiftly produced to perfectly regulate the relative spatial structure of its materials and cells, in order to better imitate the relative anatomical location of the spinal cord, using biological 3D printing. OBJECTIVE: To summarize research progress of 3D biological scaffolds in the field of tissue repair and regeneration after spinal cord injury. METHODS: Using the Chinese and English search terms “biology 3D printing, biological scaffold, three dimensional scaffold, spinal cord injury”, CNKI, WanFang, PubMed, Web of Science, Medline, and EMbase databases were searched for articles concerning 3D biological scaffolds combined with stem cell transplantation in the treatment of spinal cord injury. Totally 67 articles were eventually included. RESULTS AND CONCLUSION: (1) Biological 3D printing technology can produce 3D biological scaffolds that are more consistent with spinal cord tissue than the spatial structure and cell distribution of traditional biological scaffolds. It makes better use of the properties of each material and cell to make the synthetic spinal cord more similar to natural spinal cord tissue. However, the selection of materials and cells for bio-inks remains a challenge. (2) This paper summarizes the main role of 3D biological scaffolds loaded with different materials and cells in the treatment of spinal cord injury. Collagen has an extraordinary effect on reducing glial scar and reducing the formation of spinal cord vacuoles. Gelatin has better biocompatibility, which can better ensure the survival of transplanted cells. The anti-inflammatory effect of alginate has a good effect on the microenvironment changes after spinal cord injury. Hyaluronic acid can not only promote neural differentiation but also promote the formation of neural network. Chitosan has obvious advantages in vascular reconstruction. (3) The mechanism of effects of 3D biological scaffolds in the treatment of different types and stages of spinal cord injury remains to be further studied.  Figures and Tables | References | Related Articles | Metrics

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Application of carbon dots-based materials in bone tissue engineering Zhang Qingmei, Zhang Lupeng, Du Xiujuan, Li Bing 2023, 27 (30):  4883-4889.  doi: 10.12307/2023.801 Abstract ( 375 )   PDF (970KB) ( 173 )   Save BACKGROUND: Carbon dots show a great potential in improving the properties of materials such as polymers and bioceramics and promoting bone differentiation, so carbon dots-based bone scaffold materials are expected to be a new type of bone repair candidate.  OBJECTIVE: To provide some references for the rational design of carbon dots-based scaffold materials by introducing the application of carbon dots-based materials in bone tissue engineering.  METHODS: Articles published between 2014 and 2022 in the WanFang Data and Web of Science were searched by the first author with the search terms “carbon dots, bone tissue engineering, bone scaffold materials” in Chinese and “carbon dots, carbon-based nanomaterials, bone tissue engineering, bone scaffold materials” in English. A total of 75 articles were finally analyzed and summarized.  RESULTS AND CONCLUSION: (1) The primitive carbon dots-based materials and carbon dots-based composites have the advantages of diverse synthesis methods and simple operation, wide material sources and green environmental protection, but their ability to repair bone defects in vivo is insufficient, as well as biosafety, biodegradation and clinical adaptability need to be further evaluated. (2) Carbon dots-based fiber materials have excellent mechanical properties, thermal stability and biodegradability required for bone scaffolds, and are a new bone repair material with great advantages and application prospects. At present, the bone repair capacity applied in vivo is limited, so it is necessary to combine with bone morphogenic protein, growth factors and vascularization factors to further improve the bone repair ability. (3) Carbon dots-based hydrogel scaffold material has shown a great potential in repairing bone defects and is the best carbon dots-based scaffold material reported to repair bone defects. However, the preparation process of the material is complex and the cycle is long, so it is necessary to further explore alternative methods of synthesis that are simple and easy to make and have short cycles. (4) Primitive carbon dots-based materials, carbon dots-based composites, carbon dots-based fiber materials and carbon dots-based hydrogel materials have their advantages and disadvantages, in which the carbon dots-based hydrogels have the best effect on repairing bone defects at present. (5) The application of carbon dots-based materials to bone tissue engineering is still in the early stage of exploration, and the hemolysis, biodegradation, metabolic process and post-healing evaluation in vivo need to be further studied, and its mechanical properties, thermal stability and the ability of bone repair need to be further improved. (6) It is necessary to combine a variety of tests and characterization methods to deeply analyze the bone mechanism of carbon dots-based materials, which is the premise of designing and applying to clinical carbon dots-based bone scaffold materials.  Figures and Tables | References | Related Articles | Metrics

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Synthesis and drug loading and delivery applications of chiral mesoporous silica nanoparticles Yan Nan, Wu Xuanjing, Wang Ziqi, Wu Jing, Zhao Tongtong, Xue Yan, Zhao Weijie, Wang Lijie, Wu Zimei, Zhang Wenqing, Li Jing 2023, 27 (30):  4890-4895.  doi: 10.12307/2023.805 Abstract ( 341 )   PDF (1013KB) ( 36 )   Save BACKGROUND: In recent years, chiral mesoporous silica nanoparticle gradually becomes widely studied drug carriers. With which properties does it have unique drug delivery advantages? OBJECTIVE: To explore the key parameters that chiral mesoporous silica nanoparticles play a dominant role in drug delivery systems.  METHODS: Starting from the synthesis, molding mechanism, chiral properties, drug-carrying release properties and biosafety of chiral mesoporous silica nanoparticles, PubMed and CNKI were used to retrieve articles published from 1990 to 2022. All articles were initially screened according to the inclusion and exclusion criteria, and 49 articles with higher relevance were retained for review.  RESULTS AND CONCLUSION: In addition to the template being an important condition for the synthesis of chiral mesoporous silica nanoparticles, the surfactant, reaction temperature, pH, stirring speed, chain length of the surfactant, anions and cations and other factors also affect the structure of the synthetic materials. In the application as drug carriers, chiral mesoporous silica nanoparticles have more advantages in drug loading and delivery due to their twisted pores, such as the high pore network structure of chiral mesoporous silica nanoparticles can increase the drug loading. In general, the larger the specific surface area and pore volume of chiral mesoporous silica nanoparticles, the higher the drug loading. The pore size of chiral mesoporous silica nanoparticles can inhibit the crystal structure of drugs, and effectively change the drug crystal form to amorphous, thus significantly improving the bioavailability of drugs. How to accurately design chiral mesoporous silica nanoparticles with chiral morphology, chiral structure or molecular chirality according to drug application needs is a key problem realizing the application value of this carrier, which needs more investigation.  Figures and Tables | References | Related Articles | Metrics

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Application of poly(lactic-co-glycolic acid) copolymer microspheres in bone tissue engineering Zhang Xiaoyu, Chen Qi, Yang Xing, Hao Yuefeng 2023, 27 (30):  4896-4903.  doi: 10.12307/2023.559 Abstract ( 372 )   PDF (1144KB) ( 67 )   Save BACKGROUND: Poly(lactic-co-glycolic acid) copolymer microspheres have good biocompatibility, biosafety and biodegradability. They are widely used in bone tissue engineering as a carrier. However, they still have some shortcomings, such as a lack of hydrophilicity, the acidity of by-products, lack of functionalization, etc. Therefore, different modifications are needed for better application. OBJECTIVE: To review the application of poly(lactic-co-glycolic acid) copolymer microspheres in bone tissue engineering. METHODS: With “poly(lactic-co-glycolic acid) copolymer microsphere, PLGA microsphere, growth factor, drug delivery, modified, functional modification, composite scaffold, bone tissue engineering” as the search terms in English, the original articles collected from January 2000 to June 2022 in Web of Science and PubMed databases were searched, and screened and analyzed. Finally, 83 articles were selected for review.   RESULTS AND CONCLUSION: (1) The physical and chemical properties of poly(lactic-co-glycolic acid) microspheres are related to the ratio of lactic acid to glycolic acid, molecular weight and terminal groups. At present, the ratio of lactic acid to glycolic acid is 75:25, the molecular weight is 75 000-100 000, and the carboxyl terminated poly(lactic-co-glycolic acid) copolymer is widely used in the preparation of microspheres. (2) Now the commonly used preparation methods mainly include emulsification, microfluidic technology, electric spray, spray drying and supercritical fluid method. The specific preparation methods should be selected according to the application requirements and production conditions of microspheres. With the development of technology, there will be a more stable and efficient production method. (3) The modification of poly(lactic-co-glycolic acid) copolymer microspheres includes the loading of growth factors and drugs, functional modification and the construction of composite scaffolds based on microspheres. Loading growth factors can promote cell differentiation and angiogenesis, thus promoting the repair and regeneration of bone tissue. Loading drugs can treat a variety of bone diseases. Complex inorganic minerals can improve the mechanical properties of poly(lactic-co-glycolic acid) and provide trace elements for bone tissue growth, which are used in the treatment of bone defects. By increasing the ability of microspheres to regulate the secretion and activity of cells, participating in the immune regulation of diseases can provide new ideas for disease treatment. The composite scaffold based on poly(lactic-co-glycolic acid) copolymer microspheres can not only increase the original advantages of the scaffold, but also increase the ability of minimally invasive drug delivery and slow release. However, the clinical application needs to be further developed. (4) In the future, poly(lactic-co-glycolic acid) copolymer microspheres are expected to develop different modification methods according to the different needs of bone tissue engineering, so as to produce microspheres with specific functions for different diseases. Figures and Tables | References | Related Articles | Metrics

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Preparation and applications of decellularized extracellular matrix bioink in cardiovascular fields Jiang Honghui, Kong Yuanyuan, Liu Jing, Wang Zhihong 2023, 27 (30):  4904-4911.  doi: 10.12307/2023.552 Abstract ( 302 )   PDF (1153KB) ( 227 )   Save BACKGROUND: With the aid of computer-assisted technology, 3D bioprinting technology uses bioink loaded with living cells to achieve tissue organ construction, which brings new hope for cardiovascular tissue engineering construction with its high freedom of design, personalization and manufacturing flexibility. Bioinks are the key to 3D bioprinting technology and have been a hot research topic in the field of biomaterials and tissue regeneration in recent years. Decellularized matrix materials are a promising bioink with low immunogenicity, maintaining the original extracellular matrix components and fibrous structure, and facilitating the survival and expansion of tissue-specific cells. OBJECTIVE: To summarize the preparation and performance characterization methods of decellularized extracellular matrix bioink and its application in cardiovascular field, which is an important reference for the study of decellularized extracellular matrix bioink application in cardiovascular field.  METHODS: The Chinese and English search terms “decellularization, bioink, 3D print, vessel, cardiac” were used in the CNKI and PubMed databases, respectively, and 82 articles were finally included for analysis.  RESULTS AND CONCLUSION: (1) The basic preparation steps of decellularized extracellular matrix bioink include decellularization of biomaterials to obtain decellularized extracellular matrix, enzymatic digestion of decellularized extracellular matrix, adjustment of pH and osmotic pressure of digesting solution, and mixture with decellularized extracellular matrix pregel with cells. (2) The basic performance characterization of decellularized extracellular matrix bioink mainly includes decellularized matrix components, rheological properties, microstructure, bioactivity, mechanical properties, and biodegradability. (3) In terms of blood vessels, researchers have prepared decellularized extracellular matrix vessels with improved mechanical properties and obtained multilayer small-diameter vessels by using advanced printing techniques, material composites, and sacrificial layers, but these printing processes are complex, the vessels lack animal experimental validation, the culture conditions of multilayer vessels are not optimized, and important tests such as suture strength and burst pressure have not been performed to meet the required performance of medical devices. (4) In the area of myocardial repair, researchers confirmed that decellularized extracellular matrix bioinks are more advantageous in myocardial repair compared to collagen and GelMA. Meanwhile, researchers focused on the design of decellularized extracellular matrix myocardial patches by enhancing the mechanical strength and electrical conductivity of the material and building a microvascular network, and these patches showed some potentials for the treatment of myocardial infarction. However, no breakthrough has been made in the question of the influence of seed cell parameters (type, area density and number, etc.) on myocardial patches and the electrical coupling between myocardial patches and host tissues to meet the required performance of medical devices. (5) Therefore, although decellularized extracellular matrix bioinks have shown some potentials in constructing cardiovascular structures, decellularized extracellular matrix-based printed vascular and myocardial patches are still in the laboratory stage and have to overcome a series of problems before entering clinical applications.  Figures and Tables | References | Related Articles | Metrics

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Research advances in drug coatings for prevention of peri-implantitis Li Yaohua, Zeng Fengjiao, Chen Bin, Fan Qin, Bai Guohui 2023, 27 (30):  4912-4920.  doi: 10.12307/2023.549 Abstract ( 375 )   PDF (1093KB) ( 76 )   Save BACKGROUND: Pharmaceutical coating applied to the surface of an implant or an abutment can produce localized antibacterial, pro-osseointegration, and soft-tissue integration effects, reducing the risk of developing peri-implantitis and increasing implant success rates. OBJECTIVE: To review the current state and achievements in the application of various drug coatings for the management of peri-implantitis.  METHODS: A computer was used to search the relevant articles in the CNKI, Wanfang, PubMed, and VIP databases using the Chinese and English search terms “peri-implantitis, drug loading materials, coating, antibacterial, osseointegration, soft-tissue integration/soft tissue sealing”. The literature was screened using the inclusion and exclusion criteria. Finally, 79 papers were considered for evaluation and analysis.  RESULTS AND CONCLUSION: (1) Current drug carriers have good mechanical, thermochemical, and biological properties, which can improve the antibacterial functions of the implant/abutment surface, promote the formation of osseointegration and soft tissue sealing by loading and releasing drugs to achieve direct and/or indirect prevention of peri-implantitis, and provide a new research direction for the prevention of peri-implantitis. For example, an antimicrobial peptide coating on the abutment surface can inhibit microorganisms’ aggregation and adhesion, promote implant soft tissue sealing, prevent bacteria from invading the alveolar bone below, avoid inflammatory absorption of bone tissue, and thus prevent peri-implantitis. (2) Specific drug coatings, on the other hand, may have issues such as sudden drug release, simple function, and difficulty in continuous drug delivery and drug supplementation. In the future, by combining different carriers and drugs, improving drug loading methods, and improving coating technology, a drug coating that can “smart” control drug release and has multifunctional and “regenerative” properties will be developed by researchers. (3) While most current in vitro studies have demonstrated that drug coatings have the potential to prevent peri-implantitis, there are few in vivo animal studies and clinical studies, and more relevant studies are needed in the future to investigate whether other cells or substances in the implant nest affect drug release, as well as the effect of drug coatings under implant loading to promote the clinical promotion of drug coating.  Figures and Tables | Related Articles | Metrics