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    08 June 2021, Volume 25 Issue 16 Previous Issue    Next Issue
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    In vivo osteogenic properties of silicon-incorporated titanium dioxide nanotubes on titanium screw surface
    Zhang Xianjun, Zhao Xijiang
    2021, 25 (16):  2461-2465.  doi: 10.3969/j.issn.2095-4344.3115
    Abstract ( 161 )   PDF (950KB) ( 26 )   Save
    BACKGROUND: At present, titanium and its alloy materials are mostly used in prosthesis and bone implants. These materials have superior mechanical properties and excellent corrosion resistance, but their bioactivity is insufficient, so it is difficult to form a good chemical bond with bone tissue.
    OBJECTIVE: To prepare titanium dioxide nanotube coating containing silicon on the surface of pure titanium screw and observe its osteogenic properties in vivo.
    METHODS: Titanium dioxide nanotube layers were prepared on the surface of pure titanium screws by anodic oxidation method (positive control group). Silicon ions were deposited on the surface of titanium nanotube layers by plasma immersion ion implantation and deposition (experimental group). Pure titanium screws were used as negative control group. The morphology of each group was observed by scanning electron microscope. The three kinds of screws were implanted into the femur of SD rats. The femoral specimens were taken out at 2, 4 and 6 weeks after implantation for biomechanical test, and immunofluorescence analysis was performed at 6 weeks after implantation. The animal experiment was approved by the Ethics Committee of Experimental Animal Management and Animal Welfare of Jiangnan University. 
    RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that uniform double-layer nanotube arrays were observed in the experimental group and the positive control group, and there was no significant difference between the two groups. (2) At 2 and 4 weeks after screw implantation, the average peak pullout force of the experimental group was significantly higher than that of the positive control group and the negative control group (P < 0.05), and the positive control group was significantly higher than the negative control group (P < 0.05). At the sixth week, there was no significant difference in pullout force among the three groups (P > 0.05). (3) Immunofluorescence showed that at 6 weeks after implantation, there was almost no new bone attachment around the screw in the negative control group, and extensive new bone attachment was observed around the screw thread in the experimental group and the positive control group, among which the new bone formation was the most in the experimental group. (4) The results showed that the silicon dioxide titanium nanotube layer could significantly promote the formation of new bone around the pure titanium screw and increase the pullout force of screws.
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    Bone cement distribution of percutaneous curved vertebroplasty for the treatment of osteoporotic vertebral compression fractures
    Li Qiang, Li Jun, Luan Jian, Jin Canghai, Hao Meng, Lin Yong
    2021, 25 (16):  2466-2471.  doi: 10.3969/j.issn.2095-4344.3101
    Abstract ( 215 )   PDF (1855KB) ( 26 )   Save
    BACKGROUND: Percutaneous curved vertebroplasty is a new method for the treatment of osteoporotic vertebral compression fractures, which can achieve a good therapeutic effect, while the distribution of bone cement has not been explored thoroughly.
    OBJECTIVE: To retrospectively analyze the therapeutic effect of percutaneous curved vertebroplasty and the distribution characteristics of bone cement in the treatment of osteoporotic vertebral compression fractures.
    METHODS: A total of 28 patients with osteoporotic vertebral compression fractures of a single thoracic or lumbar vertebrate, who were admitted to Qingdao Municipal Hospital from June 2017 to February 2018, including 2 males and 26 females, aged 62-86 years old, underwent percutaneous curved vertebroplasty and were retrospectively reviewed. The bone cement was injected at the puncture side, the middle of the vertebrate and the contralateral side respectively. The change of anterior vertebral body height of the injured vertebrae and the leakage of bone cement postoperatively were observed according to X-ray images preoperatively, 48 hours and 6 months postoperatively. The bone cement distribution within the vertebrate was observed by CT scanning. Visual analogue scale score and Oswestry disability index were recorded for the evaluation of recovery. All protocols were approved by the Ethical Committee of Qingdao Municipal Hospital.
    RESULTS AND CONCLUSION: (1) There were 6 out of 28 cases of bone cement leakage, including 4 cases of paravertebral leakage and 2 cases of intervertebral space leakage, and no clinical symptoms were observed in all the 6 cases. CT scanning showed that the bone cement was mainly distributed in the anterior 2/3 of the vertebral body. The maximum distribution area of bone cement was (4.5±0.9) cm2, with the contralateral area (2.0±0.5) cm2 and the puncture side area (2.5±0.7) cm2, which makes the ratio of the puncture side area versus contralateral area 0.85±0.27. (2) The anterior vertebral body heights preoperatively showed no significant difference than those postoperatively in 28 patients (P > 0.05). (3) The visual analogue scale score and Oswestry disability index 48 hours and 6 months postoperatively were both significantly different from those before operation (P < 0.05). (4) The results showed that percutaneous curved vertebroplasty treatment of osteoporotic vertebral compression fractures has the advantages of accurate surgical effects and even distribution of bone cement.
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    Thermosensitive chitosan-collagen composite hydrogel loaded with basic fibroblast growth factor retards ventricular remodeling after myocardial infarction in mice
    Chen Siyu, Li Yannan, Xie Liying, Liu Siqi, Fan Yurong, Fang Changxing, Zhang Xin, Quan Jiayu, Zuo Lin
    2021, 25 (16):  2472-2478.  doi: 10.3969/j.issn.2095-4344.3150
    Abstract ( 247 )   PDF (1837KB) ( 42 )   Save
    BACKGROUND: Chitosan or collagen alone can improve the microvessel density in myocardial infarction area and participate in the short-term myocardial repair after myocardial infarction. Based on this research group, thermosensitive chitosan-collagen composite hydrogel was prepared, which confirmed that it had good physical and chemical properties and was suitable for myocardial tissue engineering scaffold materials.
    OBJECTIVE: To prepare the chitosan-collagen composite hydrogel loaded with basic fibroblast growth factor, and to analyze its physical and chemical properties, biocompatibility and prognosis in vivo after treatment of myocardial infarction in mice.   
    METHODS: (1) Basic fibroblast growth factor was loaded in chitosan-collagen composite hydrogel and chitosan hydrogel separately, and the release efficiency of basic fibroblast growth factor in hydrogels was detected. (2) H9C2 cardiomyocytes were seeded in two hydrogels loaded with basic fibroblast growth factor, and cell proliferation was detected by CCK8 assay. (3) C57BL/6J mice model of myocardial infarction was established and randomly divided into three groups. The blank group was injected PBS into the myocardial infarction area. The control group was injected with chitosan hydrogel loaded with basic fibroblast growth factor. The experimental group was injected with chitosan-collagen composite hydrogel loaded with basic fibroblast growth factor. Echocardiography and myocardial histology were performed 28 days after operation. The experiment was approved by Ethics Committee of Shanxi Medical University. 
    RESULTS AND CONCLUSION: (1) Compared with chitosan hydrogel, chitosan-collagen composite hydrogel could promote the release of basic fibroblast growth factor in gel. (2) Compared with the chitosan hydrogel loaded with basic fibroblast growth factor, the chitosan-collagen composite hydrogel loaded with basic fibroblast growth factor could promote the proliferation of cardiomyocytes. (3) Echocardiography showed that the left ventricular ejection fraction and the shortening rate of left ventricular short axis in the experimental group and the control group were higher than those in the blank group (P < 0.05). Left ventricular ejection fraction and the shortening rate of left ventricular short axis in the experimental group were higher than those in the control group (P < 0.05). (4) The myocardial histological observation showed that the infarct area of the experimental group and the control group was smaller than that of the blank group (P < 0.05). The infarct area wall thickness of the experimental group and the control group was larger than that of the blank group (P < 0.05). The infarct area of the experimental group was smaller than that of the control group (P < 0.05), and the infarct area wall thickness of the experimental group was larger than that of the control group (P < 0.05). (5) The results showed that the chitosan-collagen composite hydrogel loaded with basic fibroblast growth factor had good biocompatibility, and animal transplantation could significantly reduce the ventricular remodeling after myocardial infarction. 
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    Application of temperature-sensitive chitosan hydrogel encapsulated exosomes in ischemic diseases
    Liu Feng, Zhang Yu, Wang Yanli, Luo Wei, Han Chaoshan, Li Yangxin
    2021, 25 (16):  2479-2487.  doi: 10.3969/j.issn.2095-4344.3130
    Abstract ( 313 )   PDF (1355KB) ( 32 )   Save
    BACKGROUND: Exosomes derived from mesenchymal stem cells can reduce myocardial ischemia and reperfusion injury, but there are some problems such as short half-life, fast clearance and low targeting.
    OBJECTIVE: To modify and encapsulate exosomes with temperature-sensitive chitosan hydrogel to increase the retention rate of exosomes in the body, and to achieve better therapeutic effect.
    METHODS: Cell transfection method was used to knock down piR823 in exosomes derived from umbilical cord mesenchymal stem cells, and the effect of knockdown of piR823 exosomes on the proliferation and apoptosis of C2C12 cells was detected. Chitosan/β-sodium glycerophosphate temperature-sensitive hydrogel was prepared and mixed directly with exosomes to prepare chitosan/β-sodium glycerophosphate temperature-sensitive hydrogel encapsulated with exosomes. The gel-forming properties, rheology and in vitro sustained release properties of the hydrogel after encapsulation of exosomes were tested. Thirty C57BL/6J mice were taken to establish hind limb ischemia models, and randomly divided into five groups. The gastrocnemius of group A was injected with PBS; group B was injected with chitosan/β-sodium glycerophosphate temperature-sensitive hydrogel; and group C was injected with exosomes-encapsulated chitosan/β-sodium glycerophosphate temperature-sensitive hydrogel; group D was injected with exosomes; group E was injected with exosomes knocking down piR823. Limb function and recovery, blood flow, grip strength, exercise endurance and muscle regeneration were detected in each group.
    RESULTS AND CONCLUSION: (1) Exosomes knocking down piR823 inhibited the proliferation of C2C12 cells; normal exosomes inhibited hydrogen peroxide-induced apoptosis of C2C12 cells. The inhibitory effect of exosomes on apoptosis was weakened after piR823 was knocked down. (2) The hydrogel encapsulating exosomes had gel-forming properties, but the gel-forming time was shortened, and it could slowly and continuously release exosomes for more than 30 days. (3) After 28 days of hindlimb ischemia, the blood flow recovery of the left limb in group C was better than that in groups B and D (P < 0.05); it in group D was better than group E (P < 0.05); the grip strength, endurance, running time and distance of group C were better than those of groups D and B (P < 0.05), and above indexes in group D were better than in group E (P < 0.05). Muscle regeneration was better in group C than in groups B and D (P < 0.05), and it in group D was better than group E (P < 0.05). (4) The results showed that encapsulation of exosomes by chitosan/β-sodium glycerophosphate temperature-sensitive hydrogel prolonged the residence time of exosomes in vivo, significantly enhanced blood perfusion and recovery of tissue function after ischemia, and the treatment effect was more significant. 
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    Preparation and in vitro evaluation of self-assembling peptide hydrogel loaded with doxorubicin
    Zhang Xin, Lu Ying, Yao Qingqiang, Zhu Yishen
    2021, 25 (16):  2488-2493.  doi: 10.3969/j.issn.2095-4344.3114
    Abstract ( 250 )   PDF (1511KB) ( 24 )   Save
    BACKGROUND: Chemotherapy is an important method for treating osteosarcoma, but traditional small molecule therapy is not ideal for clinical efficacy and has serious adverse reactions. Therefore, it is necessary to develop a new method for osteosarcoma, which can anti-tumor at low doses and reduce adverse reactions.
    OBJECTIVE: To construct a self-assembling peptide hydrogel (SAPH) loaded with doxorubicin (DOX) and analyze its drug release performance and biocompatibility in vitro.
    METHODS: DOX was introduced into SAPH composed of FEFEFKFK (F, phenylalanine; E, glutamic acid; K, lysine), prepared to contain 20, 30, and 40 g/L DOX-SAPH of FEFEFKFK; the DOX mass concentration in this system was 2 g/L. Three kinds of DOX-SAPH were placed in PBS, and the amount of DOX released was regularly detected. Three DOX-SAPH extracts were co-cultured with rabbit bone marrow mesenchymal stem cells, and the cell survival rate was detected by CCK-8 method. The DOX solution containing different concentrations of DOX and the DOX-SAPH extract (containing FEFEFKFK 30 g/L) were co-cultured with MG63 human osteosarcoma cells, and the cell survival rate was detected by CCK-8 method. 
    RESULTS AND CONCLUSION: (1) With the increase of the concentration of FEFEFKFK in the hydrogel, the sustained release effect of DOX-SAPH was enhanced. The cumulative drug release rate of DOX-SAPH at 20, 30, and 40 g/L at the 168th hour in vitro was 88%, 83%, and 80%. (2) The cells in 20 g/L DOX-SAPH extract group proliferated faster than 30 and 40 g/L DOX-SAPH extract group at 1, 3, and 5 days in vitro (P < 0.05), in which the 40 g/L DOX-SAPH extract group had certain cytotoxicity on the first day. (3) DOX solution and DOX-SAPH extract showed concentration-dependent inhibition of MG63 cell proliferation, when the concentration of DOX in the DOX solution and the DOX-SAPH extract was lower than 12.5 mg/L, there was no significant difference in the toxicity of the two to MG63 cells (P > 0.05). When the concentration of DOX was higher than 12.5 mg/L, the cell toxicity of the DOX solution was greater than that of DOX-SAPH extract (P < 0.05). (4) The results show that DOX-SAPH has a good drug slow-release effect, which can inhibit the growth of MG63 osteosarcoma cells.
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    Effects of fish scale collagen membrane on adhesion, proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells
    Chen Liang, Meng Shu, Cheng Guoping, Ding Yi
    2021, 25 (16):  2494-2499.  doi: 10.3969/j.issn.2095-4344.3094
    Abstract ( 235 )   PDF (1316KB) ( 31 )   Save
    BACKGROUND: In recent years, fish derived collagen has been regarded as a potential substitute for mammalian collagen, and its research in biomedical materials has gradually become a hot spot. Fish scale collagen materials with preserved fish scale shape have excellent mechanical properties, and there is no research to explore whether this material has the potential of bone tissue regeneration.
    OBJECTIVE: To study the effect of fish scale collagen membrane on the adhesion, proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells. 
    METHODS: The collagen membrane was prepared from Ctenopharyngodon idellus scales. The structure of collagen membrane was observed by naked eye and scanning electron microscope. The type of collagen was identified by Fourier transform infrared spectroscopy. The denaturation temperature of collagen membrane was determined by differential scanning calorimetry. Rat bone marrow mesenchymal stem cells at passage 3 were cultured in vitro on collagen membrane as experimental group; and those received conventional cell adherent culture were used as control group. The adhesion of cells on the collagen membrane of fish scale was observed by scanning electron microscope. The proliferation activity of cells in each group was detected by CCK-8, and the osteogenic differentiation ability of cells in each group was detected by alkaline phosphatase staining. 
    RESULTS AND CONCLUSION: (1) The fish scale collagen membrane was square and round, the light transmittance was high, and the “annual ring” pattern could be seen on the surface. Scanning electron microscope showed that the fish scale collagen membrane was multi-lamellar structure, which was composed of type I collagen and hydroxyapatite, and the denaturation temperature was 50.55 ℃. (2) The adhesion of bone marrow mesenchymal stem cells on the surface of fish scale collagen membrane was good, and the cell proliferation was better than that of the control group. The alkaline phosphatase activity of the surface cells of fish scale collagen membrane was higher than that of the control group, and the difference was statistically significant. (3) Results suggested that bone marrow mesenchymal stem cells on the surface of fish scale collagen membrane have good adhesion, which can promote cell proliferation and osteoblast differentiation, and has good biocompatibility and the potential of bone tissue regeneration.
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    Effects of dispersants on aggregation, intracellular distribution and cell proliferation of nano-hydroxyapatite
    Wang Renxian, Cao Jingjing, Wang Honggang, Wan Ben, Liu Weifeng
    2021, 25 (16):  2500-2505.  doi: 10.3969/j.issn.2095-4344.3172
    Abstract ( 280 )   PDF (897KB) ( 19 )   Save
    BACKGROUND:Nano-hydroxyapatite has excellent biocompatibility, biological activity, and modifiability, but the synthesized nano-hydroxyapatite has a high specific surface energy, which makes it agglomerate in solution.
    OBJECTIVE: To compare the effects of ultrasound and different dispersants on the aggregation, cytotoxicity and intracellular distribution of nano-hydroxyapatite. 
    METHODS: Needle like nano-hydroxyapatite was prepared by chemical precipitation method, and kept for further use after high pressure sterilization. Different concentrations of dispersant sodium hexametaphosphate (0, 0.25, 0.5, 1, 2 mmol/L), sodium citrate (0, 0.25, 0.5, 1, 2 mmol/L), sodium polymethacrylate (0%, 0.0625%, 0.125%, 0.25%, 0.5%) were co-cultured with MC3T3E1 cells. Cell proliferation was detected by CCK-8 assay. The appropriate concentration of dispersant was screened for subsequent experiments. The nano-hydroxyapatite solution was divided into five groups: the control group was not dispersed; and the remaining four groups were subjected to ultrasonic dispersant, 1 mmol/L sodium hexametaphosphate dispersant, 1 mmol/L sodium citrate dispersant, and 0.125% sodium polymethacrylate dispersant. The aggregate size of nano-hydroxyapatite was detected. The hydroxyapatite was treated with ultrasound, 1 mmol/L sodium hexametaphosphate, 1 mmol/L sodium citrate, and 0.125% sodium polyacrylate dispersants and then co-cultured with MC3T3E1 cells. Undispersed nano-hydroxyapatite co-cultured with MC3T3E1 cells was considered as control. Cell proliferation was detected by CCK-8 assay. At 1 day after culture, the distribution of nano-hydroxyapatite was observed by transmission electron microscope.
    RESULTS AND CONCLUSION: (1) Sodium hexametaphosphate at a concentration of 1 mmol/L and lower had no obvious cytotoxicity. Sodium citrate at 0.25-2 mmol/L had no obvious cytotoxicity. Sodium polymethacrylate at different concentrations had certain cytotoxicity in time- and concentration-dependent manners. Subsequent experiments selected 1 mmol/L sodium hexametaphosphate, 1 mmol/L sodium citrate, and 0.125% sodium polyacrylate for dispersion treatment. (2) All three dispersants significantly reduced the agglomeration size of nano-hydroxyapatite, and sodium hexametaphosphate had the best dispersion effect. (3) The dispersion method and the addition of dispersant could significantly affect the biological function of nano-hydroxyapatite. Sodium citrate promoted the proliferation of cells co-cultured with nano-hydroxyapatite. Ultrasound and sodium polymethacrylate inhibited proliferation of cells co-cultured with nano-hydroxyapatite. (4) Transmission electron microscopy showed that in the control group and the ultrasound group, large agglomerates of nano-hydroxyapatite existed inside and outside the cell; the nano-hydroxyapatite dispersed by the three dispersants also had agglomeration, but the size of the agglomeration was significantly smaller. Among them, the nano-aggregation size of the sodium hexametaphosphate group was the smallest. Some nanoparticles were wrapped in a double-layer membrane in the cell to form a structure similar to “small vacuoles”. (5) The results show that the commonly used dispersants themselves have certain cytotoxicity, and the addition of dispersants will significantly reduce the agglomeration size of nano-hydroxyapatite and its intracellular distribution, and affect cell proliferation.
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    Antibacterial properties of Jiao Da Bio-Magnesium scaffolds in vitro
    Wang Liang, Guo Yuxing, Wu Xun, Huang Hua, Yuan Guangyin, Zhang Lei
    2021, 25 (16):  2506-2513.  doi: 10.3969/j.issn.2095-4344.3151
    Abstract ( 226 )   PDF (1451KB) ( 27 )   Save
    BACKGROUND: It has been confirmed that some biomedical magnesium alloy products have antibacterial properties, but the specific antibacterial mechanism is still unclear. 
    OBJECTIVE: To investigate the antibacterial properties of biomedical Jiao Da Bio-Magnesium scaffold in vitro and explore possible mechanism.
    METHODS: Jiao Da Bio-Magnesium porous scaffold material extract was prepared. As the most common bacteria causing orthopedic implants infection, Escherichia coli and Staphylococcus aureus were selected for testing. The bacteriostasis rate was quantitatively evaluated by contact culture of the extraction solution. The bacteriostasis performance of the material was qualitatively evaluated by observing the bacterial morphology through scanning electron microscope. The alkaline phosphatase, conductivity, potassium ion, nucleic acid and protein content in bacterial extracellular liquid environment were detected. The possible antibacterial mechanism of Jiao Da Bio-Magnesium porous scaffold material extract was preliminarily explored. 
    RESULTS AND CONCLUSION: (1) The bacteriostasis rate of Jiao Da Bio-Magnesium porous scaffold extract cultured with Escherichia coli for 12 hours ranged from 56.23% to 79.72%, while the Staphylococcus aureus group ranged from 62.34% to 76.07%. (2) Under scanning electron microscope, wizened form, smaller volume and scarcer distribution were observed. (3) The material extract had no effect on the content of alkaline phosphatase in the extracellular environment of the two bacteria, but increased the electrical conductivity and potassium ion content in the extracellular environment of the two bacteria. (4) The material extract had no effect on the content of nucleic acid and protein in the extracellular environment of Escherichia coli, and increased the content of nucleic acid and protein in the extracellular environment of Staphylococcus aureus. (5) The material extract could inhibit the nucleic acid content of the two bacteria, but had no effect on the soluble protein content of Escherichia coli cells, and inhibited the synthesis of soluble protein in Staphylococcus aureus cells. (6) Results suggested that Jiao Da Bio-Magnesium porous scaffold material has certain antibacterial properties in vitro, and the inhibitory effect on Staphylococcus aureus is stronger than that on Escherichia coli. The possible antibacterial mechanism is speculated that it can change the permeability of bacterial cell membrane and affect the synthesis of bacterial nucleic acids and proteins. 
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    Rehabilitation training combined with neurotrophin 3-chitosan scaffolds enhanced skeletal muscle morphology and functional recovery in rats with spinal cord injury
    Chen Xingying, Hao Fei, Gao Yudan, Zhao Wen, Duan Hongmei, Yang Chaoyang, Li Xiaoguang
    2021, 25 (16):  2514-2520.  doi: 10.3969/j.issn.2095-4344.3116
    Abstract ( 230 )   PDF (1412KB) ( 39 )   Save
    BACKGROUND: Previous studies have shown that neurotrophin 3 (NT3)-chitosan can induce endogenous neurogenesis and axon regeneration in rats with spinal cord injury, and promote recovery of motor and sensory functions in rats. 
    OBJECTIVE: To observe the effect of rehabilitation training combined with NT3-chitosan biomaterial scaffold on skeletal muscle morphological changes and functional recovery in rats with complete spinal cord injury.
    METHODS: Fifty adult female Wistar rats were randomly divided into five groups, 10 in each group. The sham group was not modeled; the remaining four groups were prepared with T7-T8 complete 5-mm spinal cord injury model, and the lesion control was not performed any intervention after modeling. The other three groups were given rehabilitation training, NT3-chitosan active biomaterial scaffold, NT3- chitosan active biomaterial scaffold combined with rehabilitation training intervention. Rehabilitation training started 2 weeks after modeling. Before operation, 2, 4, 6, 8, 10, and 12 weeks after operation, all of rats were subjected to double-blind open-field BBB scores. After 12 weeks, the skeletal muscles of the hind limbs (tibialis anterior muscle, gastrocnemius muscle, and soleus muscle) were taken for hematoxylin-eosin staining and acetylcholinesterase staining. The changes in muscle atrophy and motor endplates were assessed in each group. The experimental plan was approved by the Animal Experiment Committee of Capital Medical University (approval No. AEEI-2018-105).
    RESULTS AND CONCLUSION: (1) The BBB score at each time point in the sham group was higher than that in the other four groups (P < 0.05); and the scores at 8, 10, and 12 weeks after the NT3-chitosan combined rehabilitation training group were higher than the lesion control group, the lesion control combined rehabilitation training group, and NT3-chitosan group (P < 0.05). (2) At 12 weeks after operation, hematoxylin-eosin staining showed that the cross-sectional area and diameter of muscle fibers of each skeletal muscle were smaller in the other four groups than that in the sham group (P < 0.05). The cross-sectional area and diameter of muscle fibers of each skeletal muscle in the NT3-chitosan combined rehabilitation training group were higher than the lesion control group, the lesion control combined rehabilitation training group, and NT3-chitosan group (P < 0.05). (3) At 12 weeks after operation, the acetylcholinesterase staining showed that the average optical density of the acetylcholinesterase on motor endplate of the muscle was lower in the other four groups than that in the sham group (P < 0.05); the average optical density of the acetylcholinesterase of the motor endplate in the NT3-chitosan combined rehabilitation training was significantly higher than that in the lesion control, lesion control combined rehabilitation training, and NT3-chitosan groups (P < 0.05). (4) The results show that NT3-chitosan combined with rehabilitation training can effectively prevent muscular atrophy of hind limb skeletal muscles in rats with complete spinal cord injury, improve the average optical density of the acetylcholinesterase of the motor endplate, reduce neuromuscular joint degeneration, and improve rat hindlimb motor function. 
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    Preparation and properties of porous nitrogen oxygen bioglass scaffold for bone repair
    Wang Hongyuan, Wang Wei, Yang Shuqing, Dou Lixin, Liu Lijun
    2021, 25 (16):  2521-2527.  doi: 10.3969/j.issn.2095-4344.3161
    Abstract ( 218 )   PDF (1462KB) ( 24 )   Save
    BACKGROUND: Bioglass has high brittleness and poor mechanical strength, which limits its application in bone defect of bearing part. Nitrogen oxide glass has higher strength and hardness. Therefore, nitriding treatment is expected to improve the mechanical strength of bioglass. 
    OBJECTIVE: To analyze the effects of nitridation on the porosity, compressive strength, bending strength, degradation performance and mineralization activity of porous bioglass scaffolds. 
    METHODS: This experiment was based on silicate glass (SiO2-CaO-P2O5-Na2O-ZnO), and nitriding it (SiO2 was replaced by 0%, 2%, 4%, 6% Si3N4, respectively). The basic glass (SiO2-CaO-P2O5-Na2O-ZnO-Si3N4) was prepared by melting method. The polyurethane foam was used as template and organic foam impregnation method was used to prepare porous bioglass scaffolds. The porosity, compressive strength, bending strength, and degradation performance in vitro of the porous bioglass scaffolds were measured in four groups. Four groups of scaffolds were immersed in simulated body fluid for 7 days. The surface morphology of the scaffold was observed with the scanning electron microscope.  
    RESULTS AND CONCLUSION: (1) The porosity of the four groups had no statistical difference (P > 0.05). (2) With increased Si3N4 content, compressive strength and bending strength of porus bioglass scaffold increased, and there was statistical difference between each group (P < 0.05). (3) With increased Si3N4 content, the degradation performance of porous bioglass scaffolds decreased gradually in vitro. (4) Scanning electron microscope revealed that typical hydroxyapatite membrane was formed on the surface of porous bioglass scaffold without nitriding treatment and porous bioglass scaffold containing 2% Si3N4, but no hydroxyapatite membrane was formed in the other two groups. (5) Nitriding treatment can significantly enhance the mechanical strength of bioglass, but can reduce its degradation performance and mineralization activity in vitro. 

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    Preparation and performance evaluation of carboxymethyl chitosan/oxidized glucomannan/Panax notoginseng compound sponge dressing for chronic wound
    Li Jie, Xu Jianzhen, Hu Ping, Lei Qiqi, Zhang Wenning, Ao Ningjian
    2021, 25 (16):  2528-2534.  doi: 10.3969/j.issn.2095-4344.3147
    Abstract ( 208 )   PDF (1826KB) ( 34 )   Save
    BACKGROUND: Previous studies have shown that carboxymethyl chitosan/oxidized glucomannan composite sponge can be used as an excellent substrate for drug-loaded chronic wound dressings.
    OBJECTIVE: To prepare carboxymethyl chitosan/oxidized glucomannan/Panax notoginseng composite sponge and evaluate its physical and chemical properties and biocompatibility.
    METHODS: Oxidized glucomannan was prepared by sodium periodate oxidation. Panax notoginseng saponins were extracted from Panax notoginseng powder. Carboxymethyl chitosan and oxidized glucomannan were first added as mixed raw materials, and then added separately to account for mixing system 2%, 6%, 10% of Panax notoginseng saponins. Freeze-drying method was used to prepare carboxymethyl chitosan/oxidized glucomannan/Panax notoginseng composite sponge. Scanning electron microscope was utilized to observe the microstructure of the composite sponge. Porosity, steam permeability, total saponin release rate of Panax notoginseng, cell compatibility, antibacterial properties and acute systemic toxicity were detected.
    RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that there were many pores in the composite sponge that were full and evenly distributed. The total saponins of Panax notoginseng were stably and evenly attached to the inner walls and joints of the pores of the sponge. (2) As the proportion of total saponins of Panax notoginseng increased, the water absorption rate, porosity, and steam permeability gradually increased. (3) The vast majority of the total saponins of Panax notoginseng in the three kinds of composite sponges could be efficiently released in 13 hours in vitro. (4) Within 3 days after in vitro culture, the proliferation rate of fibroblasts was more than 95%. (5) Three kinds of compound sponges have an inhibitory effect on E. coli and Staphylococcus aureus, but do not have acute systemic toxicity. (6) The results show that carboxymethyl chitosan/oxidized glucomannan/Panax notoginseng composite sponge is expected to be an excellent medical chronic wound dressing.
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    Porous tantalum coated with RGD polypeptide can activate the integrin/focal adhesion kinase signaling pathway of MG63 cells
    Zhang Hui, Wang Shaohua, Wang Qian, Wang Hui, Gan Hongquan, Cui Yishuang, Li Qijia, Wang Zhiqiang
    2021, 25 (16):  2535-2540.  doi: 10.3969/j.issn.2095-4344.3117
    Abstract ( 195 )   PDF (1536KB) ( 19 )   Save
    BACKGROUND: The compounding of RGD polypeptide on the surface of the material can induce the expression of osteoblast integrin gene, promote the adhesion of osteoblasts to the surface of biomaterials and differentiate into mature cells, and promote the formation of new bone.
    OBJECTIVE: To analyze the effect of domestic porous tantalum modified by RGD polypeptide on integrin/focal adhesion kinase signaling pathway in MG63 cells.
    METHODS: Porous tantalum material modified by RGD polypeptide was prepared. MG63 cells were inoculated on the surface of porous tantalum and porous tantalum materials modified with RGD polypeptide. MG63 cells cultured alone were used as the blank group. When cultured for 1, 3, 5, and 7 days, the cell proliferation was detected by the CCK-8 method. At 1, 3, and 5 days, the cell growth status was observed under an inverted microscope. At 3, 5 days of culture, cell adhesion was observed with scanning electron microscope. At 5 days of culture, RT-PCR and western blot assay were used to detect type I collagen and integrin β1 and focal adhesion kinase expression.
    RESULTS AND CONCLUSION: (1) The cell proliferation of the RGD modified group cultured at 3, 5, and 7 days was faster than that of the porous tantalum group and the blank group (P < 0.05). There was no significant difference in cell proliferation between the porous tantalum group and the blank group at each time point (P > 0.05). (2) Observation by an inverted phase contrast microscope showed that the cells of the porous tantalum group and the RGD modified group were attached to the edge of the material when cultured for 1 day, and the number of cells gradually increased with the extension of the culture time. The number and density of cells in the RGD modified group were better than that of the porous tantalum group. (3) Observation by scanning electron microscope showed that cells adhered to the surface of the porous tantalum group and RGD modified group after 3 days of culture. The cells adhered to the material pore walls and pores, and protruded pseudopods into the pores. When cultured for 5 days, the cells secreted a large amount of extracellular matrix, and the cells were connected to each other through the matrix and gradually covered the surface of the material. The cell growth state, matrix secretion and cell coverage area of the RGD modified group were better than those of the porous tantalum group. (4) Western blot detection results showed that the expressions of type I collagen and integrin β1 protein in the RGD modified group were higher than those in the porous tantalum group and the blank group (P < 0.05). The expression levels of type I collagen, integrin β1, and focal adhesion kinase protein in the porous tantalum group were higher than those in the blank group (P < 0.05). (5) RT-PCR detection showed that the expressions of type I collagen, integrin β1, and focal adhesion kinase mRNA in the RGD modified group were higher than those of the porous tantalum group and the blank group (P < 0.05), and the expression of the porous tantalum group was higher than that of the blank group (P < 0.05). (6) The results showed that porous tantalum modified with RGD polypeptide can up-regulate the expression of type I collagen and integrin β1 on the cell membrane, activate the integrin/focal adhesion kinase signaling pathway, and promote cell adhesion and growth.

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    Establishment and functional in vitro characteristics of three-dimensional collagen HepaRG microsphere
    Li Shao, Liang Yongkang, Gao Yi, Peng Qing
    2021, 25 (16):  2541-2547.  doi: 10.3969/j.issn.2095-4344.3149
    Abstract ( 268 )   PDF (2155KB) ( 43 )   Save
    BACKGROUND: Some recent studies have shown that the three-dimensional (3D) model of HepaRG cells can better mimic the in vivo microenvironment and show better liver differentiation and function compared with two-dimensional culture. 
    OBJECTIVE: HepaRG was selected to prepare 3D collagen microspheres, and the adaptive culture and functional expression of cells in the collagen microspheres were evaluated. 
    METHODS: Collagen hydrogel was used as the scaffold for 3D HepaRG and HepG2 microspheres. Stable cell spheres were formed. HepaRG microspheres, HepG2 microspheres, HepaRG two-dimensional culture and HepG2 two-dimensional culture were used as controls. At 1, 6, and 12 days of culture, cell survival was detected by the Live/Dead assay staining. After 1, 6, 12, and 16 days of culture, the urea synthesis and CYP3A4 secretion of the supernatant were detected in each group. After 12 days of culture, relative expression of CYP3A4, CYP1A2, UGT1A1, and CPS1 mRNA was detected by qPCR. The expression levels of hepatocyte marker albumin and CYP3A4 protein were determined using western blot assay. 
    RESULTS AND CONCLUSION: (1) In 12 days of culture, Live/Dead assay staining showed that the cell viability in the 3D collagen microsphere was well-maintained and the amount of central necrotic cells was small, with high cell viability. In the 3D collagen microsphere, especially HepaRG cells, multiple cellular clusters formed and adjacent clusters were connected closely, which created a cross-linked structure. (2) After 1, 6, and 12 days of culture, the urea content of HepaRG 3D collagen microspheres was higher than that of HepaRG two-dimensional culture (P < 0.05). After 1, 6, 12, and 16 days of culture, the urea content of HepG2 3D collagen microspheres was higher than that of HepG2 two-dimensional culture (P < 0.05). After 1, 6, and 12 days of culture, the secretion of CYP3A4 in HepaRG 3D collagen microspheres was higher than that in HepaRG two-dimensional culture (P < 0.05). After 6 and 12 days of culture, the secretion of CYP3A4 in HepG2 3D collagen microspheres was higher than that in HepG2 two-dimensional culture (P < 0.05). (3) The relative expression of CYP3A4, CYP1A2, UGT1A1, and CPS1 mRNA in HepaRG 3D collagen microspheres was higher than that in HepaRG two-dimensional cells (P < 0.05), and the relative expression of CYP1A2 in HepG2 3D collagen microspheres was higher than that in HepG2 two-dimensional culture (P < 0.05). (4) The expression levels of albumin and CYP3A4 protein in HepaRG 3D collagen microspheres were higher than those of HepG2 3D collagen microspheres, ordinary microspheres, and two-dimensional culture (P < 0.05). (5) These results indicated the high-level expression of hepatocyte functions in 3D collagen HepaRG microsphere, which could be taken as a reference in drug metabolism evaluation in vitro and tissue engineering application. 
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    Analysis of liquid-solid interaction during three-dimensional printing of medical amorphous calcium phosphate
    Nie Jianhua, Cheng Jiang, Mo Jiaqi
    2021, 25 (16):  2548-2553.  doi: 10.3969/j.issn.2095-4344.3099
    Abstract ( 244 )   PDF (1082KB) ( 23 )   Save
    BACKGROUND: Based on excellent hydration ability, the materials for repairing bone defects could be fabricated by three-dimensional printing from amorphous calcium phosphate simply with pure water as adhesive solution; and more importantly, the printed products could be directly used in clinical medicine without high temperature sintering, so amorphous calcium phosphate fits well with technical features of three-dimensional printing.
    OBJECTIVE: To prepare bone repair materials of amorphous calcium phosphate with mechanical property and printing accuracy to meet practical application requirements by three-dimensional printing.
    METHODS: Amorphous calcium phosphate used as prototyping powder was prepared by coprecipitation method, and then the viscosity and surface tension of the deionized water as adhesive solution were adjusted by thickening agent and leveling agent, respectively. Afterwards, the three-dimensional printing productions for repairing bone defects were fabricated, and the effects of the viscosity and surface tension of adhesive solution on the forming of droplet, liquid-solid interaction and the mechanical property as well as printing accuracy of three-dimensional printing productions were investigated.
    RESULTS AND CONCLUSION: By investigating the forming of droplet and liquid-solid interaction, the optimal physicochemical parameters of the adhesive solution were obtained. The viscosity and surface tension of the optimal adhesive solution were 8.0 × 10-3 Pa•s and 40.0 × 10-3 N/m separately, and at this point, not only droplet could form stably and controllably (Z=5.06), but also it smoothly struck the powder layer during spraying (K=14.29), and then it infiltrated into the powder layer uniformly and spread in time (We=36.86). The corresponding three-dimensional printing production has good mechanical properties (compressive strength is 30.4 MPa), high printing accuracy (forming error is 0.9 mm), and a large number of pores indicating good bone conductivity, which partially meets clinical demands of repairing bone defects. 
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    Evaluation of silk fibroin/curcumin composite film for promoting wound healing
    Chen Zhenyu, Zhang Xiaoning, Luo Yuxin, Liang Jianwei, Yan Chi
    2021, 25 (16):  2554-2561.  doi: 10.3969/j.issn.2095-4344.3118
    Abstract ( 344 )   PDF (1412KB) ( 48 )   Save
    BACKGROUND: In the previous study, we have successfully prepared a silk fibroin/curcumin composite film, which possesses good physicochemical properties, sustained-release properties, antibacterial activity and biocompatibility.
    OBJECTIVE: To further observe the effect of the prepared silk fibroin/curcumin composite film, as the wound dressing, in the field of wound healing.
    METHODS: The silk fibroin/curcumin composite film was prepared by referring to the previously established methods. The mechanical properties and light transmittance of the prepared composite film were then investigated. Escherichia coli and Staphylococcus aureus were used as strains. The plate-counting technique was applied to evaluate the antibacterial activity of the light illuminated silk fibroin/curcumin composite film, silk fibroin/curcumin composite film without light exposure, and silk fibroin film without light exposure. The full-thickness excisional lesions were created on the dorsum of 20 Kunming mice. The wounds of 10 mice were covered with silk fibroin/curcumin composite film, and the wounds of other 10 mice were dressed with sterile gauze. The healing status and histological morphology of the wound sites were observed at 3, 7, and 14 days post operation. The animal experimental design and the protocols were approved by the Laboratory Animal Ethics Committee of Southwest University (approval number: IACUC-2019011).
    RESULTS AND CONCLUSION: (1) Compared to silk fibroin film, the fracture strength of silk fibroin/curcumin composite film increased significantly (P < 0.05), while the Young’s modulus of silk fibroin/curcumin composite film decreased significantly (P < 0.01). (2) Both silk fibroin film and the silk fibroin/curcumin composite film exhibited excellent transparency, but the silk fibroin/curcumin composite film showed a stronger absorption in visible light region at a wavelength of 400-450 nm. (3) Without light illumination, the silk fibroin/curcumin composite film exhibited stronger antibacterial activity than that of silk fibroin film. While, the silk fibroin/curcumin composite film with light illumination demonstrated stronger antibacterial activity than that of silk fibroin/curcumin composite film without light illumination. (4) The wound healing rate of the experimental group was higher than that of the control group at each time point (P < 0.05). Analysis on histological morphology reveals that the length of regenerated epithelia of dermal tissue and the thickness of granulation tissue in the experimental group were greater than those in the control group at 3 and 7 days post operation (P < 0.01). While, the thickness of granulation tissue was smaller than that in the control group at 14 days post operation (P < 0.01). (5) The results indicated that the silk fibroin/curcumin composite film can facilitate skin wound healing.

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    Enzyme-responsive nanoparticles in tumor therapy: superiority of nanoparticles in accumulation and drug release 
    Gan Zhoujie, Pei Xibo
    2021, 25 (16):  2562-2568.  doi: 10.3969/j.issn.2095-4344.3131
    Abstract ( 240 )   PDF (1010KB) ( 28 )   Save
    BACKGROUND: Based on enhanced permeability and retention effect of nanoscale drug delivery systems in tumors, intelligent design of anti-tumor drug delivery vehicles has recently become a major direction in the development of tumor treatment strategies. Among them, the enzyme-responsive nano-delivery system has played a relatively important role, taking tumor-specific and highly expressed enzymes as precise targets so as to greatly improve targeting performance. 
    OBJECTIVE: To summarize researches on the protocol, targeting efficiency and anti-tumor effects of enzyme-responsive nanoparticles in cancer treatment in recent years.
    METHODS: PubMed, Web of Science, CNKI and Wanfang databases were searched for the articles concerning the enzyme-responsive nanoparticles related to tumor treatment, with the search terms of “nanoparticles; neoplasms; enzymes; drug carriers; responsive” in English and Chinese, respectively. After initial screening of all articles according to inclusion and exclusion criteria, those with higher relevance were retained for the successive review. 
    RESULTS AND CONCLUSION: Currently, enzyme-responsive nanoparticles are classified into two basic types in the article: drug-releasing type and functional type. Both are further divided into several sub-categories. Different designs target at corresponding tumors and their microenvironment characteristics. Among them, drug-releasing enzyme-responsive nanoparticles are designed to achieve controlled release of drugs at specific sites in tumors by enzyme response, while functional enzyme-responsive nanoparticles focus on improving the targeting efficiency and accumulation of nanoparticles in tumors. Both main types achieved specific release of drugs in tumors due to corresponding enzyme response, thereby reducing systemic toxicity and improving anti-tumor effects. According to current research trends, enzyme responsiveness is gradually turning into a part of the design of multiple responsive nanoparticle antitumor drugs in coming years. More tumor-specific enzymes and response mechanisms will be discovered to cope with complex tumor types and their microenvironment as well. 
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    New strategies and problems of affinity peptide in cartilage tissue engineering
    Fu Liwei, Yang Zhen, Li Hao, Gao Cangjian, Sui Xiang, Liu Shuyun, Guo Quanyi
    2021, 25 (16):  2569-2574.  doi: 10.3969/j.issn.2095-4344.3154
    Abstract ( 244 )   PDF (750KB) ( 27 )   Save
    BACKGROUND: With the development of cartilage tissue engineering, affinity peptides have attracted some attention because of their special affinity to some key factors of cartilage tissue engineering.
    OBJECTIVE: To review the screening and identification of various affinity peptides and their application in cartilage tissue engineering.
    METHODS: The articles related to affinity peptides in CNKI, Wanfang, and PubMed were searched by computer from January 2000 to May 2020. “Affinity peptides, cartilage tissue engineering, mesenchymal stem cell, scaffold” in English and Chinese were used as key words. Finally, 66 articles were included for analysis.
    RESULTS AND CONCLUSION: Many polypeptides with specific amino acid sequence can bind with some cells, factors and molecules, and have affinity. According to different targets, they can be divided into cell affinity peptide, factor affinity peptide and extracellular matrix molecular affinity peptide. Affinity peptides have been used in cartilage tissue engineering through screening and identification to enhance the repair effect of tissue engineering by adhering fine cells, recruitment factors and molecules. In many strategies of biomimetic cartilage multilayer scaffolds, affinity peptides that interact with specific molecules play an important role in simulating the environment of normal cartilage. At the same time, with the development of cartilage tissue engineering technology, especially the application of computer-aided technology, it provides a new strategy for the use of affinity peptides. However, the residence time, degradation rate and degradation pathway of affinity peptides in vivo are relatively few, which need to be further understood.

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    Advantages and characteristics of electrospun aligned nanofibers as scaffolds for tissue engineering
    Xie Jian, Su Jiansheng
    2021, 25 (16):  2575-2581.  doi: 10.3969/j.issn.2095-4344.3768
    Abstract ( 308 )   PDF (915KB) ( 53 )   Save
    BACKGROUND: Tissue engineering technology relies on biomaterial scaffolds as supporting structures for tissue repair and regeneration. Among these biological scaffolds, electrospun fiber scaffolds have been widely applied in regenerative medicine owing to their mimicry of the natural structure of extracellular matrix.
    OBJECTIVE: To summarize the current application of electrospun aligned nanofibers in the field of tissue engineering.
    METHODS: Relevant articles included in PubMed from January 2010 to March 2020 were searched by the first author, with key words of “electrospinning; aligned nanofibers; tissue engineering; regenerative medicine; bioactive materials” in English. Relevant articles included in CNKI and Wanfang database from January 2010 to March 2020 were searched with key words of “electrospinning; aligned nanofibers; oriented fiber; tissue engineering; tissue regeneration” in Chinese. Finally, 67 articles were included for review.
    RESULTS AND CONCLUSION: Electrospinning is a simple and effective technology for the preparation of nanomaterials. In recent years, many kinds of natural materials or polyester materials with good biocompatibility and biodegradability have been prepared into electrospun nanofiber scaffolds with different structures by electrospinning technology, which are widely used in tissue engineering, regenerative medicine and other fields. Among them, the electrospun oriented nanofiber scaffolds, inspired by the highly directional characteristics of natural extracellular matrix, have highly consistent fiber arrangement direction, which can promote cell adhesion and migration through contact guidance, and the combination with cells or growth factors can further promote cell proliferation and differentiation, and ultimately achieve tissue regeneration in nerve, myocardium, tendon and bone tissue. In the field of regeneration and wound healing, it has great potential and wide application prospect.
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    Characteristics and effects of cell-scaffold composite for periodontal soft tissue augmentation
    Bi Haoran, Luo Yaxin, Chen Xiaoxu, Yang Kun
    2021, 25 (16):  2582-2588.  doi: 10.3969/j.issn.2095-4344.3119
    Abstract ( 261 )   PDF (723KB) ( 35 )   Save
    BACKGROUND: Insufficient amount of periodontal soft tissue always brings red-and-white aesthetic problems of natural teeth and restorations, leads to gingivitis and peri-implant inflammation. Cell scaffold complexes with different cell and material combinations can promote periodontal soft tissue regeneration, which is expected to replace autogenous grafts.
    OBJECTIVE: To review the research progress and breakthrough in the application of autologous or allogeneic fibroblasts, keratinocytes, and mesenchymal stem cells in periodontal soft tissue increment.
    METHODS: Literature retrieval was conducted in PubMed, CNKI, Wanfang, Sciencedirect, and Medline databases. The key words were “gingival recession, soft tissue augmentation, root coverage, subepithelial connective graft” in English and Chinese. Abstracts were read; conclusions were preliminarily screened; and studies and experiments unrelated to the topic of this paper were excluded. Finally, 61 articles were included for result analysis.
    RESULTS AND CONCLUSION: Mesenchymal stem cells show great potential in gingival papilla increment. Transplanting only fibroblasts or keratinocytes combined with collagen, chitosan, acellular dermal matrix and other scaffolds in soft tissue could not achieve the expected keratinized gingival increment. Although the combination of two kinds of cells and collagen matrix showed more optimistic results and the current scaffold materials had good plasticity and biocompatibility, co-culture of fibroblasts and keratinocytes is time-consuming and expensive, and the conformation of scaffold material is relatively single. How to solve these problems will be a long process.
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    Intervertebral disc tissue engineering based on polymer materials: research focus and hot spots
    Yang Lin, Shi Jun, Guo Zhonghua, Wang Zhonghan, Liu He, Li Qiuju
    2021, 25 (16):  2589-2596.  doi: 10.3969/j.issn.2095-4344.3096
    Abstract ( 289 )   PDF (796KB) ( 29 )   Save
    BACKGROUND: In recent years, the rapid development of tissue engineering technology provides a new idea for the treatment of intervertebral disc degeneration; that is, biomaterials are used to reconstruct the damaged intervertebral disc structure. 
    OBJECTIVE: To summarize polymer materials which are applicable for intervertebraltissue engineering construction, and overview the advantages, disadvantages and application progress of each material.
    METHODS: We searched related articles from inception to February 2020 in PubMed, Web of Science and CNKI databases with “polymer, intervertebral disc, tissue engineering, nucleus pulposus, annulus fibrosus” as English and Chinese key words. Initially 189 related articles were searched, and 109 eligible articles were included in final analysis according to inclusion and exclusion criteria.
    RESULTS AND CONCLUSION: Intervertebral disc is composed of inner soft nucleus pulposus and outer stiff annulus fibrosus. Accordingly, it requires two components with different structures and functions to reconstruct a complete intervertebral disc with tissue engineering method. Chitosan, alginate and hyaluronic acid are considered as optimal materials for nucleus pulposus construction because of their appropriate swelling character and ability of inducing cells to secrete nucleus pulposus matrix. Silk fibroin, collagen, polyethylene glycol, polylactic acid, polyglycolic acid and polycaprolactone with high mechanical strength are suitable for annulus fibrosus construction to bear high loading burden. By further surface modification, these synthesis scaffolds wound show a better cellular compatibility and promote tissue integrity after in vivo implantation. 

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    Problems and trends of technique and clinical application of metallic biomaterials prepared by three-dimensional printing technology
    Ji Qi, Yu Zhengwen, Zhang Jian
    2021, 25 (16):  2597-2604.  doi: 10.3969/j.issn.2095-4344.3081
    Abstract ( 275 )   PDF (866KB) ( 57 )   Save
    BACKGROUND: Three-dimensional (3D) printing technology has been applied to fabricate the personalized metallic biomaterials with low elastic modulus, low cost and precision, aiming at overcoming the defects of the biomaterials fabricated by the traditional technology. 
    OJECTIVE: To summarize the development of metallic biomaterials fabricated by the 3D printing technology.
    METHODS: The articles were searched by using the databases of PubMed and CNKI. The key words were “metallic biomaterials, metallic 3D printing technology, surgical implants, oral application and cardiovascular devices” in Chinese and in English. As a result, 92 articles were applied after reading and analyzing the title and abstract of the articles published between June 2010 and June 2020.
    RESULTS AND CONCLUSION: In biomedical applications, metallic 3D printing technology can be divided into two categories: powder bed selective melting and directional energy deposition. Metallic 3D printing enables mass production of metal implants with complex geometric shapes and internal structures, as well as customized medical implant production that meets the needs of specific patients. Faced with many metallic printing technologies, it is necessary to choose a suitable additive manufacturing process according to the complexity and different design of materials. At present, 3D printing of metallic biomaterials such as titanium and cobalt-chromium alloys has made substantial progress, and has been used in clinical orthopedics, dentistry and vascular surgery. Research on 3D printing metal biomaterials based on magnesium and iron is still carried on.
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    Research and application of bone connection and anti-adhesion of nanomaterial artificial ligaments
    Yan Hao, Qi Zhiming
    2021, 25 (16):  2605-2611.  doi: 10.3969/j.issn.2095-4344.3051
    Abstract ( 163 )   PDF (1205KB) ( 30 )   Save
    BACKGROUND: Irregular structures on the nanometer scale mimic the structure of natural extracellular matrix molecules, and can be used as a carrier for cell adhesion or proliferation to promote tissue regeneration at the site of implantation. 
    OBJECTIVE: To review the research progress of nanomaterial artificial ligament applied in ligament reconstruction.
    METHODS: Computer was used to search CNKI, PubMed, Web of Science, Embase, Cqvip and Wanfang databases. The search terms were “tissue engineering, nanomaterials, artificial ligaments, nanometre, nanoscale, artificial ligament”. According to the standard, the research progress of nanomaterial artificial ligament was included in the literature. 
    RESULTS AND CONCLUSION: Nanomaterials have good biological compatibility. Artificial ligaments modified by nanomaterials can provide good adhesion environment for cells and promote cell proliferation. Bone marrow mesenchymal stem cells can proliferate and differentiate on the surface of artificial ligaments modified by nanomaterials and promote the extension of bone into ligaments. This effect enhances the strength of ligaments and promotes tendon and bone healing to a certain extent. Nanomaterial scaffold is a promising solution for the treatment of ligament injuries. The current nanofiber preparation technology has laid the foundation for the implementation of this solution. Currently, the prepared nanofibers can provide ideal mechanical strength, and some nanomaterials are degradable. After implantation, they can promote the proliferation of fibroblasts and gradually replace the nanofibers until ligament regeneration is achieved. The research of nanomaterial scaffold has also made some progress in bone connection and anti-adhesion.

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    Characteristics and application of bioabsorbable materials in orthopedics
    Li Yanle, Yue Xiaohua, Nie Zhen, Zhang Junwei, Li Zhaohui, Nie Weizhi, Jiang Hongjiang
    2021, 25 (16):  2612-2617.  doi: 10.3969/j.issn.2095-4344.3148
    Abstract ( 348 )   PDF (689KB) ( 44 )   Save
    BACKGROUND:  Bioabsorbable materials have shown obvious advantages in clinical application for more than ten years, and have been widely used in many biomedical fields.
    OBJECTIVE: To review characteristics of bioabsorbable materials and their application in orthopedics.
    METHODS: The articles published in Wanfang, CNKI, VIP, and PubMed databases were searched by computer. The key words were “bioabsorbable materials, bioabsorbable metal materials, bioabsorbable inorganic materials, polymer materials, biocomposites” in Chinese, and “bioabsorbable/bioabsorbable material, metal material, polymer material, biocomposites” in English. 
    RESULTS AND CONCLUSION: Absorbable metal materials have good mechanical properties. The corrosion mechanism of polymer materials is clear, which can predict the corrosion behavior and corrosion rate in vivo and in vitro, but its load-bearing performance is not as good as that of absorbable metal materials. After certain treatment, bioceramics have good biocompatibility, bone conductivity and osseointegration, but they are brittle and difficult to be formed. Biocomposites have the properties of component materials, and can also obtain new properties that single component materials do not have, so it has a wide application prospect.
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    Meta-analysis of vacuum-sealing drainage combined with antibiotic bone cement in the treatment of chronic osteomyelitis
    Tian Lin, Shi Xiaoqing, Mao Jun, Zhang Nongshan, Zhang Li, Xing Runlin, Wang Peimin
    2021, 25 (16):  2618-2624.  doi: 10.3969/j.issn.2095-4344.3171
    Abstract ( 233 )   PDF (895KB) ( 20 )   Save
    OBJECTIVE: Vacuum-sealing drainage has the effect of promoting wound healing and preventing infection. At present, a large number of studies have confirmed the significant efficacy of vacuum-sealing drainage combined with antibiotic bone cement in the treatment of chronic osteomyelitis, but the corresponding evidence is still lacking. A meta-analysis was performed on the effect of treatment of chronic osteomyelitis by vacuum-sealing drainage combined with antibiotic bone cement.
    METHODS: CNKI, VIP, Wanfang, PubMed, Cochrane Library and EMbase were searched to find randomized controlled trials of vacuum-sealing drainage combined with antibiotic bone cement for the treatment of chronic osteomyelitis. The retrieval time was from inception to February 2020. The quality of the included literature was strictly evaluated, and the RevMan 5.3 software was used for meta-analysis of the included research. 
    RESULTS: Ten randomized controlled trials involving 637 patients with chronic osteomyelitis were included, with the treatment group of 313 cases and control group of 324 cases. Due to the special wound therapy, it was difficult to implement blind method clinically, so there was partial implementation bias. (2) Meta-analysis results showed that the recurrence rate of chronic osteomyelitis treated with vacuum-sealing drainage with antibiotic bone cement was lower than that in the control group (OR=0.20, 95%CI:0.11-0.37, P < 0.000 01). In the healing rate (OR=3.44, 95%CI:2.01-5.92, P < 0.000 01), healing time (MD=-11.05, 95%CI: -18.59 to -3.52, P=0.004), duration of antibiotic use (MD=-12.36, 95%CI: -13.27 to -11.44, P < 0.000 01), visual analogue scale score (MD=-1.94, 95%CI:-2.80 to -1.08, P < 0.000 01), times of dressing change (MD=-5.78, 95%CI:-6 .64 to -5.12, P < 0.000 01), bone absorption time (MD=-0.81, 95%CI:-0.98 to -0.64, P < 0.000 01), and bone healing time (MD=-1.62, 95%CI:-2.22 to -1.03, P < 0.000 01) were all better in the vacuum-sealing drainage with antibiotic bone cement group than those in the control group. 
    CONCLUSION: The combination of vacuum-sealing drainage and antibiotic bone cement in the treatment of chronic osteomyelitis has a significant advantage over the traditional treatment, which is worthy of clinical promotion. Limited by the quantity and quality of the included studies, the above conclusions need to be verified by more high-quality clinical studies.

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