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08 June 2023, Volume 27 Issue 16 Previous Issue    Next Issue

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Preparation and in vitro evaluation of sustained-release nanoparticles loaded with sulfasalazine Zhong Wenjing, Zhou Zihan, Wang Haoyu, Li Shangyong, Xia Yujun 2023, 27 (16):  2461-2466.  doi: 10.12307/2023.134 Abstract ( 319 )   PDF (1370KB) ( 106 )   Save BACKGROUND: Sulfasalazine has been commonly used in the treatment of ulcerative colitis. Traditional administration methods have poor absorption, low availability, and are often accompanied by serious toxic side effects. Compared with traditional drug delivery methods, colon-targeted nano-delivery can protect the drug from adverse environment and improve the local absorption and bioavailability of the drug.  OBJECTIVE: Sulfasalazine@polylactic acid-glycolic acid copolymer-chitosan-pectin-chitosan nanoparticles were prepared for characterization and vitro evaluation, and the safety of nanoparticles as drug carriers was verified at the cellular level. METHODS: The O/W emulsion method and electrostatic layer-by-layer self-assembly technique were used to prepare sulfasalazine@polylactic acid-glycolic acid copolymer-chitosan-pectin-chitosan nanoparticles. The morphology of the nanoparticles was observed using transmission electron microscopy. Laser particle sizer was used to detect nanoparticle potential and particle size. Drug loading and encapsulation rates of nanoparticles were determined by ultraviolet spectrophotometry. The nanoparticles were dissolved in PBS with different pH values (1.2, 6.8, 7.4) to detect the release of sulfasalazine by the nanoparticles. The nanoparticle solutions of different mass concentrations (10, 20, 50, 100, 200 mg/L) were co-cultured with macrophages, and after 48 hours, the cell viability was detected by CCK8 assay. The 20 mg/L nanoparticle solution was co-cultured with macrophages, and after 24 hours, rhodamine fluorescent staining was performed for the uptake of nanoparticles by cells. RESULTS AND CONCLUSION: (1) Transmission electron microscopy images showed that the nanoparticles were ellipsoidal with uniform particle size; with a particle size of 290.9 nm, a potential of 19.8 mV and a dispersion index of 0.295, with good dispersion of the individual nanoparticles. The encapsulation rate of the nanoparticles was 75.68% and the drug loading was 22.24%. (2) In vitro release experiments showed that within 36 hours, the release rate of nanoparticles increased with the increase of PBS pH. The prepared nanoparticles barely released sulfasalazine at low pH=1.2 and released slowly and continuously up to pH 7.4, indicating that the nanoparticles had pH-dependent and good slow release characteristics. (3) Different concentrations of nanoparticles had no obvious effects on the activity of macrophages and did not show cytotoxic effects. (4) Cellular uptake experiments showed that nanoparticles could be taken up by cells after 6 hours of culture. The nanoparticles entered the macrophages within 12-24 hours. (5) The sulfasalazine@polylactic acid-glycolic acid copolymer-chitosan-pectin-chitosan nanoparticles have good slow-release properties and cytocompatibility, can be taken up by macrophages with high uptake efficiency.  Figures and Tables | References | Related Articles | Metrics

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Full-thickness rotator cuff tear repair by injection of leukocyte-poor platelet-rich plasma: a comparison of low and high concentration groups Bai Xiaosong, Gao Liying, Zhang Dingding, Liu Wenlong, Zhang Tao, Shen Xiaoyang, Liang Chunyu, Sun Xiaoxin 2023, 27 (16):  2467-2472.  doi: 10.12307/2023.140 Abstract ( 335 )   PDF (1008KB) ( 96 )   Save BACKGROUND: In recent years, more and more scholars have focused on arthroscopic rotator cuff repair combined with platelet-rich plasma for the treatment of rotator cuff tears, in order to reduce the re-tear rate and improve the prognosis of patients. However, due to differences in the dosage form, activation state, frequency of use, timing of use, and concentration of platelet-rich plasma, the results of various clinical studies vary. OBJECTIVE: To evaluate the effects of different concentrations of leucocyte platelet-rich plasma on postoperative pain, functional and structural integrity outcomes in patients accepted arthroscopic rotator cuff repair.  METHODS: A total of 80 patients with full-thickness tear of the rotator cuff admitted to the Affiliated Hospital of North China University of Science and Technology and The Second Hospital of Tangshan from January to September 2020 were included. The patients were randomly divided into two groups. In the control group (n=40), cases underwent arthroscopic rotator cuff repair. In the trial group (n=40), about 3 mL of autologous leukocyte-poor platelet-rich plasma was injected under the tendon in patients undergoing arthroscopic rotator cuff repair. Among them, the platelet concentration in the low-concentration group (n=20) injected into the leukocyte-poor platelet-rich plasma was (330.20±172.65)×109 L-1, and the platelet concentration in the high-concentration group (n=20) injected into the leukocyte-poor platelet-rich plasma was (807.76±218.98)×109 L-1. Visual analog scale scores, range of motion, shoulder function score, and re-tear rate of shoulder flexion lift and abduction lift of each group were were compared.  RESULTS AND CONCLUSION: (1) Visual analog scale scores of the trial group at 12 months after surgery was lower than that of the control group (P < 0.05). The visual analog score of the high-concentration group at 14 days and 1, 3, 6, and 12 months after surgery was lower than that of the low-concentration group (P < 0.05), but it did not reach the minimum clinical significance change value. (2) There was no significant difference in the range of motion of shoulder flexion lift and abduction lift among the groups at 12 months after operation (P > 0.05). (3) The American shoulder and elbow surgeons score 12 months after the operation in the high-concentration group was higher than that in the low-concentration group (P < 0.05), but did not reach the minimum clinical significant change value. There was no significant difference in shoulder joint function American shoulder and elbow surgeons score, Constant-Murley score and University of California, Los Angeles (P > 0.05). (4) At 12 months after operation, there was no significant difference in the rotator cuff re-tear rate between the groups (P > 0.05). (5) Low and high concentrations of leukocyte-poor platelet-rich plasma cannot improve postoperative range of motion, pain, function, and re-tear rates of patients with full-thickness rotator cuff tears. Therefore, this study does not recommend arthroscopic rotator cuff repair combined with leukocyte-poor platelet-rich plasma for the treatment of rotator cuff injury. But more research will be needed to confirm this conclusion.  Figures and Tables | References | Related Articles | Metrics

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Preparation and osteoinductive properties of tricalcium phosphate ceramics with submicron topology Lu Di, Wan Xinyu, Yang Jinxin, Ding Kexin, Zhang Cheng, Duan Rongquan, Liu Zongxiang 2023, 27 (16):  2473-2479.  doi: 10.12307/2023.464 Abstract ( 336 )   PDF (2757KB) ( 30 )   Save BACKGROUND: Synthetic calcium phosphate ceramic materials are similar to the inorganic components of natural bone tissue. Functional design through surface morphology and chemical composition can endow them with excellent osteoconductive and osteoinductive properties. The development of calcium phosphate ceramic materials with osteoinductive properties is the current research hotspot. OBJECTIVE: To endow the submicron topology tricalcium phosphate ceramics with osteoinductive properties through material morphology regulation and functional design, and test their physicochemical properties and osteoinductive properties.  METHODS: Novel tricalcium phosphate ceramics were prepared by high temperature sintering method. Clinical available Bio-oss bone meal was set as the control group. The sample surface morphology, the protein adsorption capacity, and the in vitro mineralizability of the two materials were characterized. Human periodontal membrane stem cells at passage 3 were co-cultured with the extracts of the two materials. Cell proliferation was detected by CCK-8 assay. Alizarin red staining was used to detect cell mineralization performance. The human periodontal ligament stem cells at passage 3 were seeded on the surfaces of the two materials. Early osteogenesis was detected by alkaline phosphatase staining. The expression of osteogenesis-related factors was detected by qRT-PCR. RESULTS AND CONCLUSION: (1) Scanning electron microscope exhibited that both materials had microporous surfaces with granular texture. Bio-Oss particles were significantly smaller than that of tricalcium phosphate ceramics. The total porosity, macroporosity, and microporosity were similar for both materials. Tricalcium phosphate ceramics were mainly submicron pores, with a grain size of 100 nm-1.0 μm. Bio-Oss bone meal was mainly nano-scale pores. In vitro mineralization experiments displayed that the ability of the surface of tricalcium phosphate ceramics to induce bone apatite deposition was stronger than that of Bio-Oss bone meal. Compared with Bio-Oss bone meal, tricalcium phosphate ceramics could adsorb more proteins from fetal bovine serum and bovine serum albumin solution (P < 0.05). (2) CCK-8 assay demonstrated that both materials promoted cell proliferation, and there was no significant difference between the two groups (P > 0.05). (3) The alkaline phosphatase activity in the tricalcium phosphate ceramic group was higher than that in the Bio-Oss group at 4 and 7 days of culture (P < 0.05), and the number of mineralized nodules at 21 days of culture was more than that in the Bio-Oss group; the mRNA expression levels of alkaline phosphatase, osteocalcin, osteopontin and Runx-2 were higher than those in the Bio-Oss group on 7 and 14 days of culture (P < 0.05). (4) The results showed that the new calcium phosphate ceramics have superior in vitro osteoinductive properties.  Figures and Tables | References | Related Articles | Metrics

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Characterization and osteogenic ability of Mg-F membrane/icariin membrane/beta-tricalcium phosphate scaffolds fabricated by coating process combined with 3D printing Xue Peng, Du Bin, Liu Xin, Sun Guangquan, Cheng Tongfei, Chen Hao, He Shuai 2023, 27 (16):  2480-2487.  doi: 10.12307/2023.176 Abstract ( 297 )   PDF (2459KB) ( 69 )   Save BACKGROUND: Bone tissue engineering scaffolds with modified growth factors have promising applications in bone repair materials, but the rapid release of growth factors leads to composite scaffolds that can promote bone repair only at an early stage, and the coating process provides a new idea to solve this problem. OBJECTIVE: To prepare Mg-F membrane/icaritin/β-tricalcium phosphate scaffold to characterize the biological properties of the new scaffold.   METHODS: The β-tricalcium phosphate scaffold was prepared by applying 3D printing technology, and the icaritin/β-tricalcium phosphate scaffold was prepared by low energy electron beam deposition technology. Mg-F membrane/icaritin/β-tricalcium phosphate scaffolds were fabricated by pulsed laser deposition technology. The microstructure, pore diameter, porosity, wire diameter, compressive strength, and elemental composition of the scaffolds were examined, and the icaritin binding force and slow-release properties were analyzed. Rabbit bone marrow mesenchymal stem cells were co-cultured with β-tricalcium phosphate scaffold, icariin/β-tricalcium phosphate scaffold and Mg-F membrane/icariin membrane/β-tricalcium phosphate scaffold extract. Cell proliferation was measured by CCK8 assay. Rabbit bone marrow mesenchymal stem cells were co-cultured with the above three scaffolds, separately, and osteogenic induction medium was added, and the osteogenic differentiation ability was observed by alizarin red staining. RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the structure of β-tricalcium phosphate scaffold was relatively regular and the pore connectivity rate was good; the surface of the icariin membrane/β-tricalcium phosphate scaffold had relatively dense icariin membrane covering the original microscopic pores; Mg-F membrane was deposited on the surface of the icariin membrane, leaving a relatively rough and loose surface with microscopic pores. The differences in pore diameter, porosity, wire diameter, and compressive strength of three kinds of scaffolds were not statistically significant (P > 0.05). (2) The icariin binding force of Mg-F membrane /icariin membrane /β-tricalcium phosphate scaffold was better than that of icariin membrane /β-tricalcium phosphate scaffold (P < 0.05), and slow release of icariin lasted longer. (3) The results of CCK8 assay showed that the three kinds of scaffold extracts did not affect the growth of bone marrow mesenchymal stem cells. Alizarin red staining showed that at 21 days of osteogenic induction, the number of calcium nodules and the maturity of calcium nodules in the Mg-F membrane/icariin membrane/β-tricalcium phosphate scaffold group and the icariin membrane/β-tricalcium phosphate scaffold group were better than those in the β-tricalcium phosphate scaffold group. (4) The results show that the Mg-F membrane/ icariin membrane / β-tricalcium phosphate scaffold has good cytocompatibility, osteogenic ability, drug binding and sustained release properties.  Figures and Tables | References | Related Articles | Metrics

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Osteogenic effects of partially demineralized autogenous dentin particles in implant site preservation Liang Hanying, Ma Yunhao, Li Han, Li Dongyang, Zhong Weijian, Ma Guowu 2023, 27 (16):  2488-2492.  doi: 10.12307/2023.175 Abstract ( 404 )   PDF (1403KB) ( 47 )   Save BACKGROUND: Autogenous dentin particles are increasingly used in various bone augmentation surgeries. Moderate demineralization may expose collagen and growth factors on the dentin surface and promote bone regeneration, but the degree of demineralization has not been clearly reported. OBJECTIVE: To evaluate the efficacy of autogenous dentin particles demineralized with different degrees as bone graft materials on promoting bone regeneration in alveolar bone site preservation. METHODS: Six beagles were selected and the second, third and fourth premolars of bilateral mandible were extracted. After grinding, crushing, sifting, pickling, disinfection and cleaning, dentin particles with a diameter of 0.5-1.0 mm were prepared. According to the time of pickling in 2% nitric acid, the samples received undemineralized (0 minute), demineralized for 1 minute (mild), demineralized for 10 minutes (moderate) and demineralized for 40 minutes (severe). The prepared dentin particles were filled into the tooth socket respectively, and the extraction socket without implanted dentin particles was a blank control. At 6 months after surgery, the bone graft area was observed by gross inspection, radiographic examination, and histological observation. RESULTS AND CONCLUSION: (1) Gross observation: The crests of alveolar ridge in the dentin particle groups were full and discontinuous crest with depressions was found in blank control group. (2) Cone beam CT showed that continuous alveolar ridge was formed in the dentin particle groups, discontinuous alveolar ridge and low density in the center of alveolar bone in the blank control group, and uneven density in alveolar socket in the undemineralized and mild demineralized groups with scattered high density image. Uniform and higher density was displayed in alveolar sockets of the moderate demineralized group and the alveolar sockets in the severe demineralized group were empty with low density images. (3) Histological observation: A large amount of dentin particles and insect phagocytic defects in the particles of the undemineralized group were found to be surrounded by scattered new bone tissue. In the mild demineralized group, a small amount of particles remained and were surrounded by new bone. In the moderate demineralized group, there were some residual dentin particles and bone cells arranged in regular order. In the severe demineralized group, there was no residual dentin granule and bone cells were mature and arranged regularly. In the blank control group, the trabeculae in alveolar socket were arranged disorderly and bone marrow cavity was filled with abundant fibrous connective tissue. (4) It is concluded that autogenous dentin particles with different degrees of demineralization possess the potential to guide new bone formation in alveolar bone preservation. The dentin particles that are demineralized for 10 minutes demonstrated the best effects on promoting bone regeneration.  Figures and Tables | References | Related Articles | Metrics

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Preparation and properties of porous hydroxyapatite scaffolds with biphase calcium phosphate coating Li Jingna, Zeng Qingfeng, Yu Shuyin, Qin Yue, Ai Zizheng, Dong Xieping 2023, 27 (16):  2493-2500.  doi: 10.12307/2023.074 Abstract ( 406 )   PDF (1774KB) ( 82 )   Save BACKGROUND: At present, the majority of artificial bone can only be prepared into small-volume filling materials. Large sections of load-bearing bone and large-scale structural bone graft materials still face two major problems: lack of ideal bone defect repair materials and difficulty in material processing and regulating process.  OBJECTIVE: To prepare the hydroxyapatite porous bone tissue scaffold with biphase calcium phosphate coating, which is similar to the morphology and structure of human large weight-bearing bone and has certain mechanical properties, excellent biocompatibility and partial degradability and assess its property.    METHODS: Two different morphologies of hydroxyapatite (powder and whisker) and β-tricalcium phosphate powder were prepared by hydrothermal synthesis method combined with spray drying technology to evaluate the cytotoxicity of hydroxyapatite powder and β-tricalcium phosphate powder extract. Using 3D printing technology, the mixture of hydroxyapatite powder and whiskers (5%, 10%, and 15%) was prepared into a porous bone embryo scaffold. Different sintering processes were set, and the optimal combination of whisker content and sintering process, such as mechanical properties and porosity, was screened through orthogonal experiments. The hydrodynamics of the optimal combination scaffold was tested. The biphase calcium phosphate coating was coated on the porous scaffold by dipping and pulling method to in vitro assess the degradation performance of β-tricalcium phosphate powder in biphase calcium phosphate coating.  RESULTS AND CONCLUSION: (1) MTT assay showed that hydroxyapatite powder and β-tricalcium phosphate powder did not have apparent cytotoxicity. (2) Orthogonal experiment results exhibited that sintering temperature, whisker content, and sintering time were the most important factors affecting the mechanical properties of the scaffold. The optimal parameters of the prepared scaffold were explored: sintering temperature of 1 300 ℃, whisker content of 10%, sintering time of 3 hours. At this time, the compressive strength of the scaffold was 8.13 MPa and the porosity was 64.07%. (3) The simulation of fluid mechanics showed that the way of inflow and outflow of cell nutrient solution perpendicular to the cross-sectional direction of artificial bone was more conducive to the effect of the scaffold in the human body. (4) In the optical mode of the Phenom electron microscope, the pore size of the porous scaffold was 400 μm before impregnation and 250 μm after impregnation. The thickness of the coating was approximately 75 μm. β-Tricalcium phosphate in composite coating exhibited good in vitro degradation properties. (5) These results confirm that the prepared hydroxyapatite/biphase calcium phosphate coating composite scaffold is a kind of bioactive ceramic scaffold with certain high porosity and mechanical properties, excellent biocompatibility and partial degradability.  Figures and Tables | References | Related Articles | Metrics

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Properties of surface coatings for 3D printed high density polyethylene scaffolds Wang Jiejie, Yin Junfeiyang, Zhong Jing, Gong Haihuan, Wang Yilin, Zhao Yanyan, Li Yanbing, Huang Wenhua 2023, 27 (16):  2501-2509.  doi: 10.12307/2023.451 Abstract ( 292 )   PDF (1373KB) ( 159 )   Save BACKGROUND: High density polyethylene has been widely used as a repair material for cranial and maxillofacial bone defects, but its preparation method and surface activity still need further improvement. OBJECTIVE: To optimize the preparation method of high density polyethylene and improve the surface activity of high density polyethylene.  METHODS: The high density polyethylene scaffolds were prepared by extrusion 3D printing technology, and the scaffolds were immersed in dopamine solution and simulated body fluid successively to be coated with polydopamine and hydroxyapatite. The microstructure, hydrophilicity and compression modulus of the scaffolds before and after coating were characterized. Mouse embryonic osteogenic precursor cells (MC3T3-E1) and human umbilical vein endothelial cells were inoculated on the surface of the scaffold to evaluate the cytocompatibility and early osteogenic and angiogenic differentiation of the scaffold before and after coating.  RESULTS AND CONCLUSION: (1) The 3D printed high density polyethylene scaffold’s fibers were arranged regularly and pores were uniform. Characterization results showed that polydopamine and hydroxyapatite coatings were successful on the surface of the scaffolds. Compared with the unmodified scaffold, the surface water contact angle of the scaffold modified with polydopamine coating and polydopamine + hydroxyapatite coating decreased significantly (P < 0.05), and the compressive modulus did not change significantly. (2) Compared with the unmodified scaffold, the modified scaffold with polydopamine coating and polydopamine + hydroxyapatite coating could promote the adhesion of MC3T3-E1 cells and human umbilical vein endothelial cells (P < 0.05). The cell adhesion promoting effect of double coating modified group was better than that of single coating modified group (P < 0.05). Compared with the unmodified scaffold, the modified scaffold with polydopamine coating and polydopamine + hydroxyapatite coating could promote the proliferation of MC3T3-E1 cells and human umbilical vein endothelial cells (P < 0.05). The proliferation promoting effect of double coating modified group was better than that of single coating modified group (P < 0.05). Compared with unmodified scaffolds, the scaffolds modified with polydopamine coating and polydopamine + hydroxyapatite coating could promote the osteogenic differentiation of MC3T3-E1 cells (P < 0.05), and increase the expression of angiogenic factor CD31 in human umbilical vein endothelial cells. The double-coating modified group was more obvious. (3) The results showed that the high density polyethylene scaffolds coated with polydopamine and hydroxyapatite based on 3D printing technology have good cytocompatibility and early osteogenic and angiogenic differentiation ability.  Figures and Tables | References | Related Articles | Metrics

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Optimization of the preparation process of vancomycin-poly(propylene fumarate)/poly(lactic-co-glycolic acid) microspheres by star point design-response surface method#br# Wang Jianghua, Yin Dongfeng, Teng Yong, Wurikaixi·Aiyiti, Wang Xiaofeng, Mareyanmu·Aini, Jiang Houfeng, Patiguli·Aihemaiti, Wang Jing 2023, 27 (16):  2510-2517.  doi: 10.12307/2023.161 Abstract ( 384 )   PDF (1655KB) ( 52 )   Save BACKGROUND: Vancomycin is one of the first-choice antibiotics for osteomyelitis. Local administration can not only exert its antibacterial effect, but also greatly reduce systemic adverse reactions.  OBJECTIVE: To optimize the preparation process of hydrochloric acid vancomycin-poly(propylene fumarate)/poly(lactic-co-glycolic acid) microspheres, and examine its in vitro release behavior and cytotoxicity.  METHODS: The hydrochloric acid vancomycin-poly(propylene fumarate)/poly(lactic-co-glycolic acid) microspheres were prepared by the double emulsion solvent evaporation method (W1/O/W2). The encapsulation efficiency and drug loading capacity of microspheres were used as evaluation indicators. The effects of mass ratio of poly(propylene fumarate) and poly(lactic-co-glycolic acid), mass ratio of poly(propylene fumarate) and poly(lactic-co-glycolic acid) to vancomycin and dichloromethane concentration of oil phase poly(propylene fumarate) and poly(lactic-co-glycolic acid) on the preparation process were investigated by star point design-response surface method. The results were analyzed by multiple linear regression and binomial fitting. The effect surface method was used to optimize the optimal process conditions. The particle size of microspheres, the ζ potential, in vitro release behavior, and the cytotoxicity were measured.  RESULTS AND CONCLUSION: (1) The hydrochloric acid vancomycin-poly(propylene fumarate)/poly(lactic-co-glycolic acid) microspheres were successfully prepared, and the optimal preparation process of the polymer microspheres was as follows: poly(propylene fumarate): poly(lactic-co-glycolic acid) mass ratio=2.41; poly(propylene fumarate)/poly(lactic-co-glycolic acid):pharmaceutical mass ratio=3.56; CH2Cl2 concentration of poly(propylene fumarate)/poly(lactic-co-glycolic acid)=129.73 g/L; the measured average encapsulation efficiency was 83.38%; deviation of 0.63% compared to predicted value; the measured average drug loading was 18.19%; deviation of 0.55% compared to predicted value. (2) The average particle size of the microspheres was 103.902 μm. The ζ potential was -21.5 mV. The cumulative release of the microspheres prepared with the optimal formulation was (22.90±0.55)% after 3 days, and the cumulative drug release reached (43.57±1.02)% after 28 days. After 28 days, the drug release of microspheres increased significantly, and the cumulative release amount was (97.89±1.39)% at 42 days. CTS classification was grade 1. (3) The microsphere preparation process optimized by the star point design-response surface method has good predictability. The optimized preparation process has good reproducibility, is simple and easy to implement, and the prepared microspheres have good in vitro sustained-release properties and biocompatibility.  Figures and Tables | References | Related Articles | Metrics

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Repair effect of poly(lactic-co-glycolic acid) nanospheres with sustained-release of neurotrophin-3 and ganglioside GD1a on spinal cord injury in rats Xia Yu, Sun Jia, Qi Zhengyan, Ma Lin, Ma Wenqian, Niu Jianguo, Wen Yujun 2023, 27 (16):  2518-2524.  doi: 10.12307/2023.168 Abstract ( 277 )   PDF (2430KB) ( 66 )   Save BACKGROUND: Non-invasive treatment of spinal cord injury needs to be developed urgently. Nanomaterials have obvious advantages, which can deliver drugs and improve the therapeutic effect. OBJECTIVE: To fabricate sustained-release nanospheres containing neurotrophin-3 and ganglioside GD1a by poly(lactic-co-glycolic acid) and investigate their effects on the repair of spinal cord injury in rats. METHODS: Poly(lactic-co-glycolic acid) nanospheres encapsulated with neurotrophin-3 and ganglioside GD1a were prepared using oil-water emulsion volatile organic solvent method. The sustained release properties of microspheres were tested. Sixty female adult SD rats were randomly divided into five groups with 12 rats in each group. In the sham operation group, the lamina was opened and sutured directly. In the spinal cord injury group, a spinal cord T9 impingement injury model was established. In the neurotrophin group, the nanosphere suspension of slow-release neurotrophin-3 was injected into the injured area of spinal cord T9. In the ganglioside GD1a group, the sustained-release ganglioside GD1a nanosphere suspension was injected into the spinal cord T9 injury area. The experimental group was injected with nanosphere suspension of sustained-release neurotrophin-3 and ganglioside GD1a in the injured area of spinal cord T9. Open field test and BBB scoring were conducted weekly after operation. The sections were taken 4 and 8 weeks after surgery for morphological observation. RESULTS AND CONCLUSION: (1) After soaking in PBS for 14 days in vitro, the sustained-release nanospheres could continuously release neurotrophin-3 and ganglioside GD1a. (2) At 7 and 8 weeks after surgery, compared with the spinal cord injury group, the BBB score and the total open field distance of the rats increased in the neurotrophin group and the experimental group (P < 0.05). The results of Nissl staining showed that at 4 and 8 weeks after surgery, the number of motor neurons increased in the anterior horn of caudal gray matter in the experimental group compared with the spinal cord injury group (P < 0.05). At 8 weeks after surgery, the number of motor neurons increased in the anterior horn of caudal gray matter in the neurotrophin group compared with the spinal cord injury group (P < 0.05). The results of immunofluorescence staining showed that compared with the spinal cord injury group, the neurotrophin group at 8 weeks and the experimental group at 4 and 8 weeks had increased spinal white matter ventral nerve fibers (P < 0.05); the expression of myelin basic protein on the ventral side of the spinal cord white matter increased at 4 and 8 weeks in the ganglioside GD1a and experimental groups (P < 0.05); the expression of myelin basic protein in the neurotrophin group increased at 8 weeks after operation (P < 0.05); the descending propriospinal tract increased in the neurotrophin group and the experimental group at 8 weeks (P < 0.05). (3) The results showed that neurotrophin-3 microspheres alone or in combination with ganglioside GD1a microspheres could promote the survival of motor neurons and nerve fibers around the spinal cord injury site and improve the motor function of the hind limbs of rats. Figures and Tables | References | Related Articles | Metrics

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Antibacterial and hemostatic properties of chitosan collagen sponge Zhu Hong, Lin Ziheng, He Rouye, Pan Jinbin, Liu Xiaochuan, He Xiaoling, Zhang Jingying 2023, 27 (16):  2525-2533.  doi: 10.12307/2023.463 Abstract ( 555 )   PDF (3337KB) ( 132 )   Save BACKGROUND: Collagen, which has good biocompatibility and degradability, is commonly used to promote wound healing, but it is not effective in preventing wound infection because of its non-antibacterial properties. OBJECTIVE: To prepare chitosan collagen sponge by freeze-drying method, which has good antibacterial and hemostatic effects. METHODS: Chitosan solution and sodium bicarbonate solution became gel at 37 ℃. Chitosan/sodium bicarbonate/type I collagen composite sponge was prepared by freeze-drying method as the experimental group, and chitosan sponge and chitosan/sodium bicarbonate sponge were used as the control group. Scanning electron microscopy was used to observe the micro-morphology of the sponge and determine its pH value, porosity, water absorption, degradation rate and antimicrobial activity against Staphylococcus aureus and Escherichia coli. The cytotoxicity of the sponges was detected by CCK-8 assay and Live/Dead staining. The hemostatic effect of the sponges was detected by the rat model of amputation bleeding. The rat model of skin trauma was established. The tissue healing was observed by hematoxylin-eosin staining and Masson staining 7 days after sponge implantation.  RESULTS AND CONCLUSION: (1) Compared with the other sponge groups, the chitosan/sodium bicarbonate/type I collagen composite sponge had larger porosity, rougher outer wall, stronger water absorption, greater porosity and water absorption multiple, and the porosity was greater than the other sponge groups (P < 0.01). The average water absorption multiple was greater than chitosan sponge (P < 0.000 1) and chitosan/sodium bicarbonate sponge (P < 0.05). (2) Anti-Escherichia coli test results showed that Escherichia coli resistance rate was chitosan sponge > chitosan/sodium bicarbonate sponge (P < 0.001) > chitosan/sodium bicarbonate/type I collagen composite sponge (P < 0.000 1). (3) Anti-Staphylococcus aureus rate test results showed that anti-Staphylococcus aureus rate was chitosan sponge > chitosan/sodium bicarbonate sponge > chitosan/sodium bicarbonate/type I collagen composite sponge (P < 0.01). (4) Chitosan/sodium bicarbonate/type I collagen composite sponge was non-cytotoxic and could promote the proliferation of mouse fibroblasts (L929), and the pro-proliferation effect was better than that of the blank group (P < 0.05), the chitosan sponge group (P < 0.000 1) and the chitosan/sodium bicarbonate sponge group (P < 0.05). (5) Chitosan/sodium bicarbonate/type I collagen composite sponge had a good hemostasis effect, which was better than the other three groups. (6) Chitosan/sodium bicarbonate/type I collagen composite sponge was implanted into the wound on the back of rats for one week without obvious inflammation in the surrounding skin, and the contents of capillary and collagen were significantly higher than those of chitosan sponge and chitosan/sodium bicarbonate sponge. The skin tissue recovered best. (7) It is concluded that chitosan/sodium bicarbonate/type I collagen composite sponge has excellent biocompatibility, antibacterial hemostasis and tissue healing properties.  Figures and Tables | References | Related Articles | Metrics

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Preparation and property analysis of electrospinning composite sustained-release antibacterial microspheres Yang Yong, Xu Shunen, Gu Xianyang, Hua Dawei, Teng Jianxiang, Wang Zhen, Ye Chuan 2023, 27 (16):  2534-2541.  doi: 10.12307/2023.462 Abstract ( 328 )   PDF (2699KB) ( 61 )   Save BACKGROUND: Due to poor bone blood supply, intravenous antibiotics administration for treating osteomyelitis, it is difficult to achieve effective drug concentration in the focal area of osteomyelitis, poor treatment effect has been clinical bottlenecks.  OBJECTIVE: To develop a biodegradable biomaterial implant with local sustained release of vancomycin and osteogenic effect, which can promote local bone tissue repair as much as possible while treating osteomyelitis. METHODS: Vancomycin sodium alginate solutions with concentrations of 6, 12 and 18 g/L were prepared into microspheres by electrospraying; and then the microspheres were vacuum freeze-dried. Poly3-hydroxybutyrate 4-hydroxybutyrate was prepared into electrospinning solution. While electrospinning, vancomycin microspheres were added to the receiving device to wrap them in nanofibers. The electrospinning composites of vancomycin-loaded microspheres with concentrations of 6, 12, and 18 g/L were prepared respectively (denoted as P@VancoMs6, P@VancoMs12, P@VancoMs18). (1) In vitro test: MC3T3-E1 cells were seeded on three kinds of scaffolds, and cell adhesion and proliferation were detected, and the appropriate concentration of vancomycin hydrochloride was screened for subsequent experiments. MC3T3-E1 cells were seeded on P@VancoMs6 and P@VancoMs12, and osteogenic induction medium was added. The in vitro osteogenic properties of the scaffolds were evaluated by immunofluorescence staining of type I collagen and osteocalcin. P@VancoMs6 and P@VancoMs12 were co-cultured with Staphylococcus aureus, respectively, and the antibacterial properties of the complexes were analyzed by the inhibition zone test. (2) The poly-3-hydroxybutyrate 4-hydroxybutyrate scaffolds, P@VancoMs6 and P@VancoMs12 were implanted subcutaneously in SD rats separately, and the biocompatibility of the scaffolds was observed by histological sections. RESULTS AND CONCLUSION: (1) In vitro experiments: cell adhesion and proliferation experiments showed that P@VancoMs6 and P@VancoMs12 had no effect on cell proliferation and could be used in subsequent experiments. P@VancoMs6 and P@VancoMs12 could inhibit the growth of Staphylococcus aureus, and the inhibitory effect of P@VancoMs12 was more obvious. Immunofluorescence staining showed that P@VancoMs6 and P@VancoMs12 could promote cells to secrete type I collagen and osteocalcin. (2) In vivo experiment: After 4 days of subcutaneous implantation, inflammatory cell infiltration was observed in the three groups of implants, but no necrosis was found. (3) The results showed that the electrospinning scaffolds containing 6 and 12 g/L vancomycin hydrochloride-loaded microspheres played good antibacterial and osteogenic effects. Figures and Tables | References | Related Articles | Metrics

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Optimal perfusion volume of low-temperature bone cement for treatment of osteoporotic vertebral compression fractures Guo Ersong, Ma Pengpeng, Zhang Xin, Zhang Chunlin, Cai Ming, Su Feng, Liu Su, Li Wei, Hu Zhenshun, Zhang Zhimin 2023, 27 (16):  2542-2547.  doi: 10.12307/2023.419 Abstract ( 259 )   PDF (1114KB) ( 97 )   Save BACKGROUND: Previous studies reported the volume of bone cement needed to restore the strength or stiffness of the fractured vertebral body, and the data varied widely. Considering this difference may be due to the volume difference of vertebral body in different regions and individuals, the volume difference before and after fracture, and the unequal volume and distribution of bone cement. Objective: To explore the amount of bone cement needed for the treatment of vertebral fractures using biomechanical study.  Methods: Eight adult sheep were selected and 50 vertebrae were finally obtained after screening T8-L2 vertebrae. Osteoporotic compression fractures were created through experiments, and the initial strength and stiffness of the vertebral body and the height of the anterior edge of the vertebral body after the fracture were recorded. The post-fracture volume of each vertebral body was accurately calculated by finite element technique to derive the cement injection volume. According to the finite element analysis results, using Latin square design, the 50 osteoporotic vertebral compression fracture specimens were divided into the first stage and the second stage. In the first stage, 5%, 10%, 15%, and 20% polymethyl methacrylate bone cement was injected by volume of percutaneous kyphoplasty, 5 specimens per volume. In the second stage, 15%, 16%, 17%, 18%, 19%, and 20% of bone cement were injected by volume, 5 specimens per volume. The two-stage specimens were placed on a universal testing machine for compression experiments. Results and Conclusion: (1) There was no significant difference in preoperative height, width and depth, bone mineral density, strength and stiffness before and after decalcification (P > 0.05). (2) The first stage: Compared with preoperative data, postoperative vertebral strength decreased in 5%, 10%, and 15% groups (P < 0.05), and postoperative vertebral strength increased in 20% group (P < 0.05). Postoperative vertebral stiffness in all four groups decreased (P < 0.05); postoperative vertebral strength and stiffness were greater in 15% and 20% groups than those in 5% and 10% groups. (3) The second stage: Compared with preoperative data, postoperative vertebral strength decreased in 15%, 16%, and 17% groups (P < 0.05), and postoperative vertebral strength increased in 18%, 19%, and 20% groups (P < 0.05). Postoperative vertebral strength was higher in 18%, 19%, and 20% groups than that in the 15% group (P < 0.05). Compared with preoperative data, postoperative vertebral stiffness in each group decreased (P < 0.05). There was no significant difference in postoperative vertebral stiffness among the six groups (P > 0.05). (4) The results show that in a certain range, under the premise of ensuring that there is no leakage of bone cement, the biomechanics and height of the fracture vertebral body can be restored to the best by using 16% bone cement combined with bilateral percutaneous kyphoplasty.  Figures and Tables | References | Related Articles | Metrics

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Application of injectable hydrogel in spinal cord injury Tao Jingwei, Fan Xiao, Jiang Shengyuan, Deng Bowen, Zhang Yaqi, Liu Gang, Zuo Xinwei, Zhou Zhuoluo, Zhao Yi, Ren Jingpei, Xu Lin, Mu Xiaohong 2023, 27 (16):  2548-2555.  doi: 10.12307/2023.173 Abstract ( 540 )   PDF (1011KB) ( 65 )   Save BACKGROUND: Injectable hydrogel has a broad application prospect and unique therapeutic plasticity in the treatment of severe spinal cord injury.  OBJECTIVE: To review the research progress of injectable hydrogels in spinal cord injury.  METHODS: PubMed, Web of Science, Embase, CNKI, Wanfang, VIP, and China Biomedical Literature Database were searched. The key words were “spinal cord injury, spinal fracture, injectable hydrogel” in Chinese and “spinal cord trauma, myelopathy, traumatic, injuries, spinal cord, spinal cord injury, spinal cord transection, spinal cord laceration, post-traumatic myelopathy, spinal cord contusion, injectable hydrogel” in English. The related studies of injectable hydrogel in the treatment of spinal cord injury were screened.  RESULTS AND CONCLUSION: Injectable hydrogel can be injected in animal and cell experiments to repair spinal cord injury. Injectable hydrogel has the characteristics of fewer traumas and can fit irregular defects. Injectable hydrogel with electrical conductivity and temperature sensitivity has a good repair function for spinal cord injury in terms of physical and chemical properties. Injectable hydrogel with stem cells or neurotrophic factors is beneficial to nerve regeneration and repair of local microenvironment of spinal cord injury. Injectable composite hydrogels have a bright future in clinical application.  Figures and Tables | References | Related Articles | Metrics

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Systematic review of the research progress of nickel-titanium arch wires for orthodontics Liu Wenwen, Cui Zhanqin, Liu Yingqi 2023, 27 (16):  2556-2562.  doi: 10.12307/2023.468 Abstract ( 445 )   PDF (1008KB) ( 177 )   Save BACKGROUND: During orthodontic treatment, the arch wire is an important part of the fixed appliance. The choice of arch wire largely determines the efficiency of tooth alignment. Among them, nickel-titanium alloys are widely used in fixed orthodontics due to their superelasticity and shape memory effect, and have become a research hotspot. OBJECTIVE: To review the development history and research progress of nickel titanium arch wires. METHODS: The literature search was performed in PubMed, Web of Science and CNKI databases. The Chinese and English keywords were “orthodontics, NiTi”. The articles were screened according to the inclusion and exclusion criteria. Finally, 77 articles were included for review.  RESULTS AND CONCLUSION: Many scholars did researches to overcome the drawbacks of the NiTi arch wire, such as improving the composition, manufacturing process and surface modification. However, the current finished nickel-titanium arch wires still have various drawbacks, such as poor aesthetic properties of the arch wires; the release of nickel ions may cause allergic reactions, and the aesthetic coating is easy to fall off. Although there are commercial products of NiTi arch wire and are widely used in clinical orthodontic treatment, due to the complexity of orthodontic process, and many researchers are still in the laboratory stage; there is no ideal NiTi arch wire to meet the needs of all aspects of orthodontic clinical treatment. The improvement of various types of NiTi arch wire is an important supplement and development to the existing NiTi arch wire, and is expected to play a huge role in clinical applications in the future.  Figures and Tables | References | Related Articles | Metrics

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Research progress and application prospect of polyethyleneimine in bone tissue engineering Huang Yixuan, Du Bin, Liu Xin, Yuan Xinwei, Xi Hongzhong, Guo Mingbin, Mai Jianbin 2023, 27 (16):  2563-2570.  doi: 10.12307/2023.137 Abstract ( 691 )   PDF (918KB) ( 99 )   Save BACKGROUND: As a cationic polymer, polyethyleneimine has been widely studied in many fields of medicine. With its rich amino and cationic charges, it has the ability of easy modification and electrostatic adsorption, which has potential advantages and prospects for application in bone tissue engineering. OBJECTIVE: To summarize the research progress of polyethyleneimine in bone tissue engineering, and discuss and explore its development prospect in bone tissue engineering. METHODS: Relevant articles were searched on PubMed, Web of Science, CNKI, and Wanfang databases from January 2000 to March 2022 with the search terms of “polyethyleneimine, bone tissue engineering, bone tissue regeneration, bone tissue repair, regenerative medicine, drug delivery” in English and Chinese. Finally, 57 articles were included for analysis.   RESULTS AND CONCLUSION: (1) The complex formed by polyethyleneimine and osteogenic genes based on gene technology is an efficient gene carrier, which can induce seed cells to express osteogenic cytokines and promote osteogenic differentiation. Modification with different groups can reduce the toxicity to seed cells such as mesenchymal stem cells as much as possible without affecting the transfection efficiency of polyethyleneimine. However, no consensus was reached on the key parameters such as the length of DNA and polyethyleneimine chains, charge density of polyethyleneimine, structure and chemical modification, and nitrogen/phosphate. (2) Polyethyleneimine has been optimized in the aspects of biocompatibility, degradation rate, pore size and mechanical strength of the scaffold as a surface coating or a composite prepared directly with the scaffold material. Meanwhile, the application of polyethyleneimine and its derivatives in bone defect repair scaffolds can give the antibacterial activity of scaffolds and enhance the ability of promoting angiogenesis. (3) In terms of in vivo loading of osteogenic inducible factor, the osteogenic inducible factor gene carried by polyethyleneimine had efficient transfection ability in vitro cell experiments. When loaded on the scaffold and implanted into the bone defect animal model, the biocompatibility of the scaffold could be improved, and the bone defect repair effect was ideal, and no serious adverse reactions were reported. However, ectopic gene insertion and promoting ectopic expression of bone protein are still existing problems. (4) In order to achieve targeted drug bone delivery, polyethyleneimine is a “bridge” between target and drug carrier with its abundant modifiable groups. (5) The targeted drug delivery method based on bisphosphonates, stimulus response system and biotin avidin system has not been reported yet, but the current application of polyethyleneimine in the field of drug delivery provides the possibility of realizing this idea, which is worth further exploration.  Figures and Tables | References | Related Articles | Metrics

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Application of allograft bone materials in spinal fusion Cai Yuanqing, Liu Mozhen, Li Zhonghai 2023, 27 (16):  2571-2579.  doi: 10.12307/2023.139 Abstract ( 360 )   PDF (980KB) ( 112 )   Save BACKGROUND: It is necessary to select an effective bone graft material in spinal fusion. Autograft was considered as the “gold standard” of spinal fusion, but there are complications such as donor site morbidity. Allograft can avoid complications associated with harvesting and donor’s volume is sufficient. Different allograft bone materials exhibit its excellent osteogenic ability when using at different sites of spine in spinal fusion. OBJECTIVE: To review the application status quo of allograft material in spinal fusion in recent years.  METHODS: Relevant articles in Chinese and English published in PubMed, Web of Science and CNKI Database from 1990 to 2022 were retrieved. Search terms were “fresh frozen bone, autograft, allograft, freeze-dried bone, demineralized bone matrix, allograft spacer, spinal fusion” in English and Chinese, separately. After screening, 95 articles were included and reviewed.  RESULTS AND CONCLUSION: Fresh frozen allograft is less used clinically due to its risk of immune rejection and transmission of disease. The fusion effect of freeze-dried bone is similar to autograft bone despite its delayed union in the end. Demineralized bone matrix is a useful graft material when it is used as a graft extender in combination with autograft or to fill the cages to play its biggest fusion ability. The combination with a carrier such as calcium sulfate or hydroxyapatite results in a significant increase in its plasticity and osteogenic activity. The new anatomic allograft spacer has good osteogenic activity, high clinical fusion rate and is effective in maintaining the intervertebral space height and the normal shape of intervertebral foramen. A large number of existing clinical studies have shown that allograft bone material can achieve the same fusion efficiency as autograft bone in spinal fusion, and is as safe and effective as autograft bone. It is a good choice for surgeons and has been widely used in clinical practice. Figures and Tables | References | Related Articles | Metrics

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Selection and biological characteristics of repair materials for skull base reconstruction Huai Peng, Zhang Yipeng, Wang Xi, Wang Wei, Wang Liang, Chen Lei 2023, 27 (16):  2580-2586.  doi: 10.12307/2023.172 Abstract ( 322 )   PDF (862KB) ( 41 )   Save BACKGROUND: Transnasal-sphenoidal neuroendoscopic surgery has become the most common surgical method for anterior skull base midline and lateral skull base location due to its characteristics of minimal invasion, full exposure and quick recovery. With the continuous expansion of surgical indications, the scope of skull base opening becomes larger and larger, then the incidence of postoperative cerebrospinal fluid leakage is correspondingly increasing. Severe cerebrospinal fluid leakage can cause fatal intracranial infection. Therefore, after neuroendoscopic resection of tumors, reliable skull base reconstruction is an essential condition for successful surgery. In this paper, the principles and methods of skull base reconstruction and biological properties of different materials used in skull base reconstruction are reviewed. OBJECTIVE: To expound the principles and methods of skull base reconstruction, summarize the research progress of different reconstruction materials and the role of different biological characteristics in skull base reconstruction. METHODS: Articles were retrieved on Wanfang and PubMed databases published from January 2012 to January 2022. The Chinese and English search terms were “skull base reconstruction, neuroendoscopy, skull base bone defect, transnasal-sphenoidal operative approach, multiple repair, pedicled mucosal flap, polyether-ether-ketone (PEEK), hydroxylapatite”. Finally, 60 articles were included for review.  RESULTS AND CONCLUSION: (1) Even if the skull base defect is getting bigger and bigger, the purpose of skull base reconstruction is still to prevent cerebrospinal fluid leakage and avoid serious complications after transnasal-sphenoidal neuroendoscopic surgery. Multilayer repair is a universally accepted principle. (2) Bone-like materials such as polyether-ether-ketone and hydroxylapatite for bony support are less clinically used because of their high price and cumbersome preoperative preparation. Clinicians mostly rely on dural-like biomaterials and pedicled mucosal flaps to complete the repair. However, limited by the weak repair support and the blood supply of the mucosal flap, a small number of patients still have a certain risk of cerebrospinal fluid leakage. (3) Therefore, intraoperative dura-like and bone-like structure artificial biomaterials and pedicled mucosal flaps to repair skull base defects are in line with the restoration of the anatomical repair of the skull base, and are helpful for the regeneration of the dura and bone structures. The research and development of biomaterials integrating hydrophobic tissue + dural-like mater + bone-like structure + mucosa have great prospects for skull base reconstruction.   Figures and Tables | References | Related Articles | Metrics

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Research and application of local drug delivery system in promoting fracture healing Jia Yuanyuan, Duan Mianmian, Tang Zhenglong 2023, 27 (16):  2587-2594.  doi: 10.12307/2023.169 Abstract ( 639 )   PDF (1234KB) ( 58 )   Save BACKGROUND: Due to the unique anatomical and physiological characteristics of bone and the dose dependence of osteogenic drugs, the local drug delivery system in fracture area is still limited. In recent years, with the development of tissue engineering technology and the refinement and controllability of drug delivery system, the research of targeting drug delivery system has become a hot spot. The local system for promoting fracture healing can be loaded with a variety of bone promoting factors, and a variety of different biological compounds can also be used synergistically to accelerate fracture healing. OBJECTIVE: To describe the process of the local drug delivery system in promoting fracture healing. METHODS: The Chinese and English key words were “drug delivery, fracture”. PubMed and CNKI were used to retrieve articles published from January 1990 to February 2022 by computer. Finally, 130 articles were included and analyzed. RESULTS AND CONCLUSION: The carriers for local delivery can be divided into three dimensional porous scaffolds, hydrogels, nanoparticles and microspheres. They have the following characteristics: good biocompatibility and biodegradability, controllable particle size, high specific surface area, easy to prepare, etc. The drug delivery system can carry osteopromoting ingredients, including stem cells, growth factors, drugs and RNAi. Targeting drug delivery system has the advantages of simple dose control, noninvasive administration and less side effects, which makes this treatment method have an ideal treatment prospect. Figures and Tables | References | Related Articles | Metrics

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Application and characteristics of Super-Bond C&B in dental clinical practice for 40 years Chen Siyu, Xue Tianyuan, Wang Jianing, Wu Wei, Jin Jianing, Zhan Desong, Fu Jiale 2023, 27 (16):  2595-2601.  doi: 10.12307/2023.469 Abstract ( 380 )   PDF (1559KB) ( 125 )   Save BACKGROUND: Since Super-Bond C&B was released in 1982, it has developed a wide range of applications and markets in multiple dental field of bonding between interfaces and various materials, attributed to 40 years of clinical case examination and scientific research accumulation. OBJECTIVE: To review the development history, chemical composition, bonding mechanism, clinical indications and the differences between Super-Bond C&B and other conventional resin cements, in order to help the clinicians to choose the appropriate bonding system in cementation process of complex cases of dental treatment.  METHODS: Based on the Chinese search terms “Super-Bond C&B, Bonding mechanism; Super-Bond C&B, Chemical property; Shear bond strength” and the English search terms “Super-Bond C&B, MMA/TBB, 4-META, Resin, Bond strength, Adhesive, Ceramics’’, the relevant documents were searched and matched in Wanfang, VIP, CNKI and PubMed databases. The retrieval time was from 1962 to July 2022. The 67 articles were finally included.  RESULTS AND CONCLUSION: As a filler-free pure resin bonding system with satisfied biocompatibility and bonding performance, the Super-Bond C&B is widely used in the treatment of dental clinical diseases, such as: cementation of dental restorations, dental tissue bonding, adhesion of orthodontic brackets and periodontal loose tooth fixation. Compared with other resin cements and bonding agents, the Super-Bond C&B has excellent adhesive properties, mechanical properties, biological compatibility, stable clinical manifestations and broad clinical applicability; therefore, it has a high clinical application value. Figures and Tables | Related Articles | Metrics

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Application and research strategy of all-ceramic cantilever bonded bridge for anterior teeth Hu Jiaxin, Shi Qianhui, Yang Jing, Pang Qiyuan, Bai Jingjing, Liu Jing, Luo Yi 2023, 27 (16):  2602-2608.  doi: 10.12307/2023.132 Abstract ( 505 )   PDF (1006KB) ( 83 )   Save BACKGROUND: All-ceramic cantilever bonded bridge has become a hot topic in the clinical aesthetic restoration of anterior teeth due to its advantages in treatment time, invasiveness, aesthetics and price. OBJECTIVE: To summarize the solutions to the clinical technical difficulties of all-porcelain cantilever bonded bridge and its advantages in the application of anterior teeth, and to introduce the clinical follow-up methods of the existing all-porcelain cantilever bonded bridge, in order to provide clinical and scientific guidance in the field of aesthetic repair of partial dentition defects of anterior teeth. METHODS: The articles published from 1955 to 2021 were retrieved by the first author on Web of Science, PubMed, CNKI, and Wanfang databases. The English search terms were “denture, partial, fixed, resin-bonded, resin bonded bridge, Maryland bridge, adhesive bridge, single-retainer, all-ceramic”. The Chinese search terms were “bonded bridge, Maryland bridge, adhesive bridge, all-ceramic, cantilever, single-retainer”. Totally 60 articles were summarized for review after screening. RESULTS AND CONCLUSION: (1) Effective surface pretreatment with zirconia ceramic material could prevent the occurrence of fracture. Designing the retention form of the box-shaped hole near the gap side and the nail hole at the bulge of the tongue is one of the current consensus of experts, which can effectively reduce the occurrence of bonded bridge shedding and improve the long-term retention effect. Under the condition of meeting the indications, the all-ceramic cantilever adhesive bridge has the advantages of low incidence of complications such as caries and periodontal disease, good aesthetic effect, and long retention time, and can be used as a permanent restoration. (2) For clinical studies, in addition to counting the basic success rate of retention rate, it is recommended to simultaneously use the oral health-related quality of life questionnaire, satisfaction questionnaire, and the American Public Health Association prosthesis evaluation criteria to comprehensively evaluate the repair effect. (3) It should be noted that different studies have defined the retention rate and success rate differently, which makes certain deviation for data statistics. Therefore, the actual clinical effect of all-ceramic cantilever bonded bridge is worthy of further investigation. Figures and Tables | References | Related Articles | Metrics

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Application of endovascular steerable catheter system in interventional surgery Guo Tingting, Cui Chaoqiang, Liu Baokun, Gu Hao, Zhou Dong 2023, 27 (16):  2609-2615.  doi: 10.12307/2023.109 Abstract ( 393 )   PDF (989KB) ( 105 )   Save BACKGROUND: Due to the complex and diverse shapes of blood vessels in the human body, the continuous weakening of force conduction between the handle and the tip of the steerable catheter in clinical practice often causes the tip deformation to fail the surgeon’s expectation, which makes the operation more difficult. How to achieve rapid and precise deformation of the steerable catheter tip during surgery has always attracted the attention of surgeons. In recent years, the rapid development of smart materials has made it possible to remotely control the deformation of the catheter tip outside the body. OBJECTIVE: To review research progress of steerable catheter system in recent years in order to provide a valuable reference for the future development of the steerable catheter system. METHODS: Articles were retrieved from Web of Science, PubMed, CNKI and Wanfang Database, and the retrieval time limit was from 1995 to 2021. All articles were initially screened by comparing the inclusion and exclusion criteria, and 41 articles were finally included for review. According to the deformation mechanism of the steerable catheter, the functional characteristics and clinical applications of the manually steerable catheter system, the magnetically driven catheter system and the soft material driven catheter system are summarized. RESULTS AND CONCLUSION: (1) The deformation mechanisms of the steerable catheter system are various, among which: the tip of the manually manipulated catheter is operated by the distal handle, so that the force is conducted along the joystick to achieve the deformation of the tip; the magnetically driven catheter is mainly by adding a magnet part of the current or the computer-controlled permanent magnet generates a magnetic field in the patient to achieve the deformation of the tip; the soft material is used to deform the catheter tip through some stimulation such as electricity or temperature. (2) Manually manipulated catheters and magnetically driven catheters are more common in interventional surgery, but manual manipulation of catheters increases the difficulty for surgeons due to their difficulty in good control and lack of positioning accuracy. Due to the expensive cost, surgeries of magnetically driven catheters (robot catheter system) cannot be applied to all patients. Therefore, it is necessary to develop a class of steerable catheters that are inexpensive and can be precisely deformed. (3) The shape memory polymer materials are cheap and have better biocompatibility than the previous materials used in catheters, and they can be accurately deformed under some human-friendly stimulation conditions (such as temperature, humidity, magnetic field, and light) through simple programming, which has a good prospect of medical application. Figures and Tables | References | Related Articles | Metrics

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Molecular mechanism of angiogenesis promoted by medical metal materials Zhou Lanxi, Shao Lu, Dong Shiwu, Yu Zhengwen 2023, 27 (16):  2616-2624.  doi: 10.12307/2023.107 Abstract ( 434 )   PDF (1318KB) ( 91 )   Save BACKGROUND: Angiogenesis is essential for tissue repair and regeneration. Improving the ability of medical metal materials to promote angiogenesis is a research hotspot in recent years. OBJECTIVE: To sort out and discuss the possible molecular mechanism of medical metal materials for promoting endothelial cell vascularization, so as to lay a foundation for the subsequent research and development of various medical metal materials for promoting angiogenesis. METHODS: Related articles were searched from PubMed, ScienceDirect, CNKI, and Wanfang databases with the key words of “medical metal materials OR alloy”, “stent OR scaffold”, “vascularization OR angiogenesis”, “molecular mechanism OR signaling pathway”, “endothelial cells” in English and Chinese. Finally, 76 articles were included and analyzed. RESULTS AND CONCLUSION: (1) The metal ions released during the degradation of implanted medical metal materials can affect angiogenesis by promoting the proliferation, migration, adhesion and tube formation ability of endothelial cells. (2) Magnesium, zinc, copper, strontium, cobalt and other metal ions can induce angiogenesis by activating Wnt, PI3K/Akt, MAPK, hypoxia-inducible factor-1α/vascular endothelial growth factor and other signaling pathways, up-regulating the expression of vascular endothelial growth factor, platelet derived growth factor, hypoxia-inducible factor-1α and other angiogenic factors, and promoting the production of angiogenic related cytokines. (3) The immune response induced by implantation not only affects the stability of the implant material, but also affects the effect of vascularization and osteogenesis. (4) The concentration of metal ions can affect the process of angiogenesis. The rapid degradation of metal materials and the accumulation of metal ions can lead to cytotoxicity. Determining the optimal concentration of metal ions to promote vascularization and osteogenic differentiation is the key to the development of multifunctional metal materials. (5) Improving the corrosion resistance of metal materials and regulating the release rate of metal ions by means of alloying and surface modification are beneficial to creating a good microenvironment for osteogenesis and angiogenesis and accelerating tissue repair and regeneration. (6) Although the mechanism of metal-promoting angiogenesis is abundant, the specific molecular mechanism is not completely clear and further research is still needed.  Figures and Tables | References | Related Articles | Metrics