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    08 September 2023, Volume 27 Issue 25 Previous Issue    Next Issue
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    Ability of medical wound dressings to resist penetration of bloodborne pathogens
    Shi Guangbo, Li Xiuting, Liu Xingcui, Guo Xianhu, Li Longfei, Wang Wenqing
    2023, 27 (25):  3937-3941.  doi: 10.12307/2023.548
    Abstract ( 314 )   PDF (1041KB) ( 68 )   Save
    BACKGROUND: The methods for testing the bacterial barrier properties of medical wound dressings are available; however, the ability of medical wound dressings to resist penetration of bloodborne pathogens still needs further study.
    OBJECTIVE: To investigate the ability of four kinds of wound dressings to resist penetration of bloodborne pathogens by simulating clinical conditions.
    METHODS: The abilities of four kinds of wet-to-dry wound dressings (nonwoven, film, polyurethane foam, and hydrocolloid dressings) to resist penetration of bloodborne pathogens were tested using Phi-X174 Bacteriophage Penetration Test System. 
    RESULTS AND CONCLUSION: (1) The nonwoven dressing had plaques formed by the penetration of phage Phi-X174, however, the film, polyurethane foam, and hydrocolloid dressings did not have plaques formed by the penetration of phage Phi-X174. (2) These results suggest that the film, polyurethane foam, and hydrocolloid dressings, but not the nonwoven dressing have the ability to resist penetration of bloodborne pathogens.
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    Biomechanical analysis of implant selection for maxillary posterior teeth based on healing process simulation
    Xu Dapeng, Jing Jie, Ma Lu, Qu Aili
    2023, 27 (25):  3942-3948.  doi: 10.12307/2023.505
    Abstract ( 222 )   PDF (1858KB) ( 32 )   Save
    BACKGROUND: Clinical trials have shown that the diameter and shape of implants affect the implant effect, but effect of the length of implants on different implant types is still controversial.
    OBJECTIVE: From the perspective of healing process simulation, finite element technique was used to analyze the mechanical differences of different implants after implantation. 
    METHODS: CAD software was used to establish three kinds of implants (conventional implants, short implants and ultrashort implants) and bone meal geometric models. The loss of maxillary 16 teeth (first molar) was simulated to establish the maxillary sinus internal lift model. The finite element model was established after dividing the mesh and imposing boundary conditions. Loading was selected in the adjacent teeth from 3 to 5 months postoperatively, and loading in the implant from 6 to 9 months. Biomechanical analysis of the implant and its surrounding soft and hard tissues was performed after solving for the optimal implant to find the best implant. 
    RESULTS AND CONCLUSION: (1) The maximum displacements were concentrated in the cervical part of the implant, and the displacements of the three kinds of implants were less than 100 μm during vertical loading. The displacement change of conventional implants during the whole healing cycle was the minimum. When adjacent teeth were loaded, the maximum displacements of short and ultrashort implants were similar, and the difference between the displacements of them increased when implants were loaded. (2) During lingual loading, the displacements of the three kinds of implants were more than 100 μm. The maximum displacement occurred on the lingual side. When the adjacent teeth were loaded, the displacement of the conventional implant was the maximum; when the implant was loaded, the displacement of the ultrashort implant far exceeded that of the conventional and short implants. (3) During lingual and distal mid loading, the maximum displacements were concentrated in the cervical part of the three kinds of implants. The displacements of the implants were all larger than those during vertical and lingual loading. When adjacent teeth were loaded, the displacement of conventional implants was greater than that of short and ultrashort implants. When the implants were loaded, the displacement differences among the three kinds of implants were significantly reduced, and the maximum displacements appeared in the implant neck. (4) The stresses on the alveolar bone in the ultrashort implant group were 81.62 MPa and 73.35 MPa for lingual and distal mid loading, respectively. The stresses on the alveolar bone in the rest of the models were less than 53 MPa. (5) Results concluded that conventional implants should be preferred for implant restorations, followed by short implants and finally ultrashort implants. Inclined loading is more likely to cause implant failure than vertical loading.
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    Preparation and performance evaluation of calcium sodium carboxymethyl cellulose/ hydroxypropyltrimethyl ammonium chloride chitosan multilayer dressing
    Pan Wei, Li Shuyang, Liu Jinhui, Liang Cheng, Duan Ke, Chen Xingtao
    2023, 27 (25):  3949-3955.  doi: 10.12307/2023.171
    Abstract ( 284 )   PDF (2002KB) ( 36 )   Save
    BACKGROUND: Moist dressings have been widely accepted, but they usually lack antibacterial properties, and their hemostatic activity and moisture-retention can be further improved.
    OBJECTIVE: To construct calcium sodium carboxymethyl cellulose/hydroxypropyltrimethyl ammonium chloride chitosan multilayer dressing, and to investigate its physical-chemical properties and evaluate antibacterial, hemostatic and biocompatible performances. 
    METHODS: Calcium sodium carboxymethyl cellulose was prepared by ion exchange method, and calcium sodium carboxymethyl cellulose / hydroxypropyltrimethyl ammonium chloride chitosan multilayer dressing (calcium sodium carboxymethyl cellulose:hydroxypropyltrimethyl ammonium chloride chitosan=2:1, 1:1, 1:2) was prepared based on interfacial polyelectrolyte complexation. The water absorption and water vapor transmission of the multilayer films were determined. Fourier transform infrared spectrometry, scanning electron microscopy and energy dispersive spectroscopy were used to characterize the composition, morphology and structure of the multilayer films. The hemostatic performance, antibacterial activity and cytocompatibility of the multilayer films were evaluated by whole blood clotting, plate counting count and co-culture method, respectively.
    RESULTS AND CONCLUSION: (1) Fourier transform infrared spectrometry and energy dispersive spectroscopy revealed that multilayer film dressing was successfully constructed. Scanning electron microscopy exhibited that the multilayer film was composed of calcium sodium carboxymethyl cellulose layer, hydroxypropyltrimethyl ammonium chloride chitosan layer and polyelectrolyte complex interface layer, which was formed by interfacial complexation. (2) The three multilayer films absorbed water rapidly in the first 10 minutes, and then the water absorption rate gradually slowed down and showed a stable trend. Compared with the dissolution tendency of pure calcium sodium carboxymethyl cellulose film, the multilayer film could be stable for a long time without collapsing after absorbing water in PBS. The water vapor transmission rates of the three multilayer films were lower than those of pure calcium sodium carboxymethyl cellulose films. (3) Pure calcium sodium carboxymethyl cellulose film had no antibacterial properties. The multilayer film had antibacterial properties. With the increase of the proportion of hydroxypropyltrimethyl ammonium chloride chitosan in the multilayer films, the antibacterial rate against Staphylococcus aureus and Escherichia coli increased. (4) The procoagulant property of the multilayer film (1:2) was weaker than that of the multilayer film (2:1, 1:1) and the pure calcium sodium carboxymethyl cellulose film. (5) CCK-8 assay showed that the proliferation rate of fibroblasts on the multilayer film (1:2) was lower than that on the multilayer film (2:1, 1:1) and pure calcium sodium carboxymethyl cellulose film (P < 0.05). Under the laser confocal microscope, the fibroblasts on the membranes of each group grew well and were spindle or polygonal. (6) The results show that the calcium sodium carboxymethyl cellulose/hydroxypropyltrimethyl ammonium chloride chitosan multilayer film has good water absorption, moisturizing, hemostatic and antibacterial properties. 
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    Preparation and characterization of nano-hydroxyapatite/aspirin/polyvinyl alcohol/gelatin/sodium alginate hydrogel scaffolds
    Li Shaoping, Yang Yuqing, Xiao Wenyundeng, Yin Lulu, Liu Libo, Liu Ying, Sun Yifan, Chen Zhiyu
    2023, 27 (25):  3956-3963.  doi: 10.12307/2023.459
    Abstract ( 315 )   PDF (1998KB) ( 124 )   Save
    BACKGROUND: Aspirin is a classic non-steroidal anti-inflammatory drug. Appropriate doses of aspirin can regulate immunity and promote osteogenesis. The preparation of bone tissue engineering materials, which can release aspirin, regulate the immune microenvironment of the bone defect area and accelerate the repair of the bone defect, and is a current research focus.
    OBJECTIVE: To prepare a novel hydrogel scaffold that can modulate the immune microenvironment and quickly repair the bone defect area.
    METHODS: Hydrogel scaffolds containing 0%, 10% and 20% of nano-hydroxyapatite/aspirin/polyvinyl alcohol/gelatin/sodium alginate were prepared. The microstructure, porosity, chemical composition, crystal structure, drug release properties, mechanical properties, swelling properties and degradation properties of the hydrogel scaffolds were characterized. The biocompatibility of the hydrogel scaffolds was evaluated by cell proliferation and cytotoxicity experiments. 
    RESULTS AND CONCLUSION: (1) Scanning electron microscope and porosity results showed that hydrogel scaffolds in the 0% nano-hydroxyapatite group and 10% nano-hydroxyapatite group had better biomimetic hierarchical porous structure, pore connectivity, and porosity. (2) The results of Fourier transform infrared spectroscopy and X-ray diffraction showed that the raw materials in the hydrogel scaffold were combined by physical and chemical double cross-linking, and the crystal phase structure of nano-hydroxyapatite was not be destroyed. (3) The results of mechanical properties showed that the 10% nano-hydroxyapatite group had the best compressive modulus and compressive strength. (4) The results of drug release properties showed that the cumulative release rate of aspirin decreased with the increase of nano-hydroxyapatite, but the drug burst release rate decreased and the sustained release time prolonged. (5) The results of swelling properties and degradation properties showed that with the increase of nano-hydroxyapatite, the swelling rate and degradation rate of hydrogel scaffolds of each group decreased. (6) Using the hydrogel scaffold extract to culture mouse pre-osteoblasts, the results of cell proliferation and cytotoxicity experiments showed that the hydrogel scaffold extract could promote cell proliferation, without cytotoxicity. (7) It is concluded that 10% nano-hydroxyapatite hydrogel scaffolds have better bionic characterization and biocompatibility, and are expected to be used as bone tissue engineering scaffolds for further studies of osteogenesis and immunomodulatory potential.
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    Sealing effect of nano hydroxyapatite on dentinal tubules
    Yu Lanning, Wang Qian, Jin Youshi, Fei Xiaowen, Wang Qingshan
    2023, 27 (25):  3964-3970.  doi: 10.12307/2023.418
    Abstract ( 317 )   PDF (1091KB) ( 77 )   Save
    BACKGROUND: Nano hydroxyapatite is an excellent bioactive material, which has a certain protective effect on demineralized enamel and dentin, but the effect and mechanism of its solution on remineralization of demineralized dentin are not clear. 
    OBJECTIVE: To explore the feasibility of nano hydroxyapatite in the prevention and treatment of dentin sensitivity and dentin caries. 
    METHODS: Abandoned human bicuspid specimens were collected, and 72 dentin slice samples were prepared from isolated bicuspids. The samples were randomly divided into 6 groups, with 12 samples per group: After demineralization, each group was immersed in 10% nano hydroxyapatite solution (group A), 6% bioactive glass solution (group B), 10% nano hydroxyapatite and 6% bioactive glass composite solution (group C), 0.05% sodium fluoride (group D), artificial saliva (group E), and deionized water (group F). After 14 days of treatment, working surfaces of samples were observed by scanning electron microscope. The surface composition was detected with energy spectrum analyzer. Dentin Rhodamine B staining was detected under a confocal laser microscope. 
    RESULTS AND CONCLUSION: (1) Scanning electron microscopy: The dentinal tubules orifice in group A was completely sealed, and the surface of the dentin was uniformly covered by a layer of tightly connected granular material. The dentinal tubules in group C were partially sealed. A small amount of scattered particles were found on the dentin surface and in the dentinal tubules of group B, group D and group E, and the dentinal tubules were open. In group F, there was no particulate matter deposition on the dentin surface or in the dentinal tubules, and the dentinal tubules were open. (2) X-ray energy dispersive spectrocopy results: The Ca/P ratio of group A was 1.61, which was closest to the theoretical value of healthy dentin; the Ca/P ratio was higher in group A than that in the groups B, E, and F (P < 0.05). There was no significant difference in Ca/P ratio between group A and group C (P > 0.05). (3) Laser confocal microscopy test results showed that the fluorescence intensity and fluorescence area of group A were the smallest, and the mean fluorescence intensity was smaller in group A than that in other five groups (P < 0.05). The mean fluorescence intensity of group C was lower than that of groups B, D, E and F (P < 0.05). (4) It is indicated that nano hydroxyapatite has a good remineralization effect on demineralized dentin. The combination of nano hydroxyapatite and bioactive glass can also deposit on the dentin surface, but there is no synergistic effect. The sealing effect is not as good as that of nano hydroxyapatite alone. 
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    Silk fibroin collagen composite scaffold combined with platelet-rich plasma for repairing skin injury
    Liu Jichao, Zhao Jinlong, Yu Yang
    2023, 27 (25):  3971-3976.  doi: 10.12307/2023.416
    Abstract ( 262 )   PDF (1165KB) ( 41 )   Save
    BACKGROUND: Tissue engineering scaffolds constructed by collagen and silk fibroin are widely used in tissue engineering fields such as skin, nerves, blood vessels, bone, and cartilage. Platelet-rich plasma is a platelet concentrate obtained by centrifuging blood twice. It contains a variety of growth factors required for tissue repair and can promote tissue regeneration and wound healing. 
    OBJECTIVE: To observe the effect of silk fibroin collagen scaffold combined with platelet-rich plasma on skin wound healing. 
    METHODS: Silk fibroin collagen scaffolds and SD rat platelet-rich plasma were prepared separately. Totally 48 8-week-old SD rats were selected, and 2 full-thickness skin defect wounds with a diameter of 2 cm were made on the back of each rat. They were randomly divided into four groups (n=12). In the blank group, normal saline was injected into the defect site. Silk fibroin-collagen composite scaffolds were implanted in the defects of the simple scaffold group. The platelet-rich plasma group was injected with allogeneic platelet-rich plasma at the wound margin. In the combined group, silk fibroin-collagen composite scaffolds were implanted in the defect site and allogeneic platelet-rich plasma was injected into the wound margin. Wound healing rate, wound inflammatory factor level, wound histological morphology and related protein expression were detected after model establishment.
    RESULTS AND CONCLUSION: (1) The wound healing rate of the combined group on days 7 and 14 after modeling was higher than that of the blank group, the simple scaffold group, and the platelet-rich plasma group (P < 0.05). (2) The levels of tumor necrosis factor α and interleukin-6 in the combined group on days 7 and 14 days after modeling were lower than those in the blank group, the simple scaffold group, and the platelet-rich plasma group (P < 0.05). (3) On day 14 after modeling, hematoxylin-eosin staining and Masson staining showed that only a few new capillaries and disordered collagen fiber tissue were seen at the defect site of the blank group. A large number of new capillaries and glandular tissue were observed in the other three groups. Collagen fibers were arranged more regularly, among which the combined group had the most new blood vessels, the glandular tissue layers were clearer, and the collagen fibers were arranged more regularly. Immunohistochemical staining displayed that the density of CD31+ cells in blank group, simple scaffold group and platelet-rich plasma group was lower than that in combined group (P < 0.05). (4) Western blot assay results showed that, compared with the blank group, the simple scaffold group, and the platelet-rich plasma group, the protein expression levels of type I collagen, type III collagen, and matrix metalloproteinase inhibitor 1 in the wound were increased in the combined group (P < 0.05), and the protein expression levels of matrix metalloproteinase 3 and matrix metalloproteinase 9 decreased (P < 0.05). (5) It is concluded that fibroin collagen scaffold combined with platelet-rich plasma can promote wound healing by inhibiting inflammatory response, increasing microvascular density and regulating the metabolic balance of extracellular matrix.
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    Local injection of ginsenoside Rg1 nanoparticles in the treatment of myocardial infarction in rats
    Cao Congcong, Ling Gengfei, Yang Chunhua
    2023, 27 (25):  3977-3983.  doi: 10.12307/2023.506
    Abstract ( 296 )   PDF (1131KB) ( 68 )   Save
    BACKGROUND: Ginsenoside Rg1 can reduce myocardial cell apoptosis and inflammatory response in mice with myocardial infarction, and improve cardiac function in mice. However, most previous studies used intraperitoneal injection. There are few related studies on the application of ginsenoside Rg1 in nanoparticles for myocardial infarction.
    OBJECTIVE: Ginsenoside Rg1 was coated with nanoparticles to observe the effect of local application on myocardial infarction in rats.
    METHODS: Ginsenoside Rg1 nanoparticles were prepared by double emulsion method. The particle size, morphology, potential, sealing rate and drug loading of the nanoparticles, as well as the sustained drug release effect in vitro were detected. Sixty-four male Sprague-Dawley rats were randomly divided into four groups (n=16). In sham operation group, only laparotomy was performed without ligation of the left anterior descending coronary artery. In the model group, ligation of left anterior descending coronary artery was conducted to make myocardial infarction model. In the medicine group, after myocardial infarction model was established, ginsenoside Rg1 was intraperitoneally injected. In the nanoparticle group, ginsenoside Rg1 nanoparticle suspension was injected into the peri-infarct area after replicating the myocardial infarction model. Echocardiogram, myocardial histology and RT-qPCR were conducted 28 days after operation. 
    RESULTS AND CONCLUSION: (1) The average particle size of the ginsenoside Rg1 nanoparticles was (231.28±3.66) nm and the Zeta potential was (-24.31±3.65) mV. Transmission electron microscopy showed that the nanoparticles were spherical with a particle size of about 198 nm. The nanoparticles were evenly dispersed without agglomeration and the encapsulation efficiency of the nanoparticles was (69.82±3.21)%. The drug load was (6.05±0.02)%. The nanoparticles could release ginsenoside Rg1 for more than 30 days. (2) Echocardiogram demonstrated that compared with the sham operation group, the left ventricular function and structure of the model group were abnormal. Compared with the model group, the left ventricular function and structure were significantly improved in the medicine group and nanoparticle group; the improvement was more obvious in the nanoparticle group. (3) Hematoxylin-eosin staining and Masson staining showed that the myocardial tissue fibers of the rats in the model group were loosely arranged and irregular; the interstitial edema was accompanied by obvious congestion and inflammatory cell infiltration, and a large amount of collagen deposition was seen in and around the ischemic center. The fibers of the myocardial tissue of the rats in the medicine and nanoparticle groups were slightly loose, and the arrangement was more regular than that in the model group. The interstitial edema and inflammatory cell infiltration were less common, and the collagen deposition in and around the ischemic center was significantly reduced. Among them, the pathological improvement in the nanoparticle group was more obvious. (4) RT-qPCR detection exhibited that compared with the model group, the mRNA expression of hypoxia-inducible factor 1α, von Willebrand factor, vascular endothelial growth factor A, angiopoietin 1, connexin 43, and cadherin increased in the medicine group and nanoparticle group (P < 0.05), and the mRNA expression of tumor necrosis factor α, interleukin-1β, and interferon γ decreased (P < 0.05), and the improvement was more obvious in the nanoparticle group. (5) Local administration of ginsenoside Rg1 nanoparticles can inhibit the inflammatory response and ventricular remodeling of infarcted myocardial tissue, improve cardiac function, and promote the repair of myocardial tissue. This effect may be associated with the expression of myocardium functional proteins and genes that inhibit inflammatory factors through the promotion of vascular-related genes.
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    Biocompatibility and in vitro osteogenic differentiation of alginates/chitosan/58S bioglass composite membrane for guided bone regeneration
    He Fan, Shan Xianfeng, Xiong Xiuli, Wang Xuejin
    2023, 27 (25):  3984-3991.  doi: 10.12307/2023.508
    Abstract ( 262 )   PDF (1431KB) ( 67 )   Save
    BACKGROUND: Natural biopolymers have excellent biodegradability. Their structures are similar to natural extracellular matrix, which is conducive to tissue repair. Natural biopolymers have a great potential in developing new absorbable membranes. 
    OBJECTIVE: To develop a new absorbable membrane for guided bone regeneration by incorporating 58S bioglass powders into alginate/chitosan composites and study the physical, chemical and biological properties. 
    METHODS: Alginate/chitosan/bioglass composite membranes were prepared according to the concentration gradient of 0, 5, 7.5 and 10 g/L 58S bioglass. The groups were recorded as 0BG, 0.5BG, 0.75BG and 1BG composite membranes according to the concentration gradient. The morphology of each group of composite membranes was characterized by metallurgical microscope and scanning electron microscope. The physiochemical properties of the resultant polymers were assessed via Fourier transform infrared spectroscopy and swelling ratio in each group. The biological properties of the composite membranes were compared by in vitro degradation experiments, protein adsorption experiments, cell adhesion experiments, cell proliferation experiments and alkaline phosphatase activity tests in each group. 
    RESULTS AND CONCLUSION: (1) Metallurgical microscope and scanning electron microscope showed that samples of each group had the typical porous structure of hydrogel, and the bioglass particles were embedded in the pores of the composite membrane. The porosity of all composite membranes was greater than 90%. The sequence was: 0BG > 0.5BG > 0.75BG > 1BG. (2) Fourier transform infrared spectroscopy exhibited the characteristic peaks of the polymer formed by alginate and chitosan and the evidence of the existence of bioglass in the polymer. The composite membranes with 58S bioglass powders showed certain advantages in swelling ratio, in vitro degradation and biological activity, and this advantage was more obvious with the increase of bioglass content. In particular, 0.75BG and 1BG composite membranes could exhibit a high level of osteogenic differentiation over a long period of time. (3) These results suggested that in the experimental research range, when the mass concentration of 58S bioglass was 7.5 and 10 g/L, the alginate/chitosan/bioglass composite membranes can achieve relatively excellent biological activity, and it has the potential to be applied in the study of guided bone regeneration.
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    Effects of icariin combined with injectable chitosan/collagen composite hydrogel on angiogenesis in rats with myocardial infarction
    He Wenfeng, Xue Cheng, Zheng Jiankang, Shuai Zhuang, Yue Rongchuan
    2023, 27 (25):  3992-3998.  doi: 10.12307/2023.550
    Abstract ( 247 )   PDF (1610KB) ( 26 )   Save
    BACKGROUND: Icariin can be used in the treatment of cardiovascular diseases, however, its high lipid solubility, poor water solubility, and obvious hepatic first-pass effect result in low bioavailability, which limits its clinical application.
    OBJECTIVE: To observe the effects of icariin combined with injectable chitosan/collagen composite hydrogel on myocardial infarction in rats.
    METHODS: Chitosan/collagen composite hydrogels loaded with different concentrations (0.4, 0.8, and 1.6 mg/mL) of icariin were prepared and marked as CS/COI/ICA0.4, CS/COI/ICA0.8, and CS/COI/ICA1.6, respectively. The cytocompatibility and sustained release performance of the hydrogels were tested. The left anterior descending artery of adult SD rats was ligated to establish a myocardial infarction model. Ninety-six myocardial infarction rat models were randomly divided into four groups (24 rats in each group): model, CS/COI/ICA0.4, CS/COI/ICA0.8, and CS/COI/ICA1.6 groups, and the infarct area, peri-infarct area and posterior wall area of rats in these four groups were injected with PBS or hydrogels. Normal rats were selected as normal controls. The experimental parameters were measured after 28 days of treatment.
    RESULTS AND CONCLUSION: (1) In vitro cell experiments showed that chitosan/collagen composite hydrogels loaded with different concentrations of icariin had good cytocompatibility, which was beneficial to the proliferation and survival of cardiomyocytes. The release of icariin from all the three hydrogels kept for more than 32 days. (2) The animal experiments showed that the cardiac structure of rats in the model group was severely remodeled and the cardiac function was significantly decreased compared with the normal control group (P < 0.01). The CS/COI/ICA0.4, CS/COI/ICA0.8, and CS/COI/ICA1.6 groups had a significant improvement in cardiac structure and cardiac function compared with the model control group (P < 0.05), with the most significant improvement in the CS/COI/ICA1.6 group (P < 0.05). Masson staining showed that the degree of myocardial fibrosis in the CS/COI/ICA0.4, CS/COI/ICA0.8, and CS/COI/ICA1.6 groups was significantly less (P < 0.05), while the thickness of ventricular wall was significantly greater compared with that in the model group (P < 0.05). Immunohistochemical staining and quantitative reverse transcription-polymerase chain reaction showed that the immunoreactivities of CD31 and α-smooth muscle actin and mRNA expression of vascular endothelial growth factor and basic fibroblast growth factor were significantly decreased compared with the normal control group (all P < 0.05), while those were significantly increased in the CS/COI/ICA0.4, CS/COI/ICA0.8, and CS/COI/ICA1.6 groups compared with the model group (all P < 0.05). (3) These findings suggest that chitosan/collagen/icaricin composite hydrogels can stimulate angiogenesis by increasing the expression of vascular endothelial growth factor and basic fibroblast growth factor in myocardial tissues in infracted areas to improve the local microenvironment of myocardial tissue due to insufficient perfusion, thereby inhibiting ventricular remodeling and improving cardiac function.
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    Physicochemical properties of chitosan/bone powder/cellulose nanocrystals scaffold loaded with antimicrobial peptides for jaw repair
    Yu Aimin, Xu Ting, Zhu Yunying, Liang Jianqiang, Wu Donghui
    2023, 27 (25):  3999-4005.  doi: 10.12307/2023.412
    Abstract ( 315 )   PDF (1771KB) ( 67 )   Save
    BACKGROUND: It is difficult for a single biomaterial to reach the standard of an ideal scaffold material for bone tissue engineering. It is an effective way to construct an ideal scaffold by compounding and complementing the advantages of multiple biomaterials. 
    OBJECTIVE: To construct a new type of mandibular scaffold, and test the key physicochemical properties of the scaffold.
    METHODS: Antimicrobial peptide-loaded carboxymethyl chitosan/bone powder/cellulose nanocrystals scaffold was prepared by freeze-drying method. The microstructure of the scaffold was observed and analyzed, and the tensile strength and elongation at break of the scaffold were measured. The water absorption, degradation rate in vitro, thermal stability and release of antimicrobial peptide of the scaffold were evaluated. 
    RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the scaffolds had a uniform porous network structure with an average pore size of 114. 9 μm. The water absorption rate of the scaffold was 698.8±53.8%. The fracture elongation of the scaffold was 8%-10%. The tensile strength was 0.7-0.9 MPa, and the stress-strain relationship was similar to that of natural cartilage tissue. (2) Thermogravimetric curve displayed that the weight loss of the stent was very slight below 200 °C, obvious between 200-400 °C, and severe above 600 °C. (3) The results of drug release in vitro showed that (58.40±1.79)% of antibacterial peptide was released from the scaffold within the first 12 hours, and the drug release rate decreased after 12 hours, and nearly 20% of antibacterial peptide was not released after 6 days, which was beneficial to the sustained and stable drug effect. (4) The scaffolds were separately soaked in PBS and PBS containing lysozyme. At 28 days, the degradation rates of scaffolds without lysozyme and with lysozyme were 70% and 85%, respectively. (5) These results exhibited that the carboxymethyl chitosan/bone powder/cellulose nanocrystals scaffold had good water absorption performance, thermal stability, degradation performance and mechanical property. 
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    Terpinen-4-ol with antibacterial properties promotes osteogenic differentiation of MC3T3-E1 cells
    Guo Pengda, Liu Keke, Duan Xin, Liu Zhaohui, Zhang Yuntao
    2023, 27 (25):  4006-4012.  doi: 10.12307/2023.545
    Abstract ( 246 )   PDF (1887KB) ( 87 )   Save
    BACKGROUND: Terpinen-4-ol has been found to have a significant antibacterial activity against pathogenic bacteria associated with peri-implantitis and can reduce the formation of surface biofilm and the occurrence of peri-implantitis when applied to the surface of titanium implants; however, the studies regarding its biosafety are lacking.
    OBJECTIVE: To explore the antibacterial effects of terpinen-4-ol on Staphylococcus aureus and Streptococcus mutans and its effect on the growth and osteogenic differentiation of MC3T3-E1 cells.
    METHODS: Different concentrations of terpinen-4-ol were dissolved in dimethyl sulfoxide. The minimum inhibitory concentration and minimum bactericidal concentration of pineolene 4 alcohol solution against Staphylococcus aureus and Streptococcus mutans were tested. The 1/2 minimum inhibitory concentration, minimum inhibitory concentration, and minimum bactericidal concentration of pineolene 4 alcohol were tested by bacteriostatic zone test. MC3T3-E1 cells were treated with different concentrations (0%, 0.3%, 0.2%, 0.1%, v/v) of terpinen-4-ol in medium or calcification-inducing solution. The proliferation activity of cells was detected by CCK-8 assay. Cells were stained with rhodamine-phalloidin to observe cytoskeleton. Differentiation ability of cells was detected by alkaline phosphatase activity assay. The formation of mineralized nodules was observed by alizarin red staining. The mRNA expression of Runx2 and osteocalcin was detected by real-time reverse transcription-polymerase chain reaction.
    RESULTS AND CONCLUSION: (1) Minimum inhibitory concentration and minimum bactericidal concentration of terpinen-4-ol against Streptococcus mutans were 0.1% (v/v) and 0.4% (v/v) respectively and against Staphylococcus aureus were 0.03% (v/v) and 0.125% (v/v) respectively. With the increase of the concentration of terpinen-4-ol, the diameter of bacteriostatic zone was significantly increased (P < 0.05). (2) CCK-8 assay showed that terpinen-4-ol promoted the proliferation of MC3T3-E1 cells, with the most obvious effects in the 0.2% group. (3) Rhodamine-phalloidin staining showed that terpinen-4-ol promoted the adhesion of MC3T3-E1 cells. (4) Alkaline phosphatase activity assay and alizarin red staining showed that terpinen-4-ol promoted the early differentiation and mineralization of MC3T3-E1 cells, with the most obvious effects in the 0.2% group. (5) Real-time reverse transcription-polymerase chain reaction showed that the mRNA expression of Runx2 was significantly higher in the 0.3%, 0.2%, and 0.1% groups than in the 0% group at 1 day of calcification induction (P < 0.05), and the mRNA expression of Runx2 and osteocalcin was significantly higher in the 0.2% and 0.1% groups than in the 0.3% and 0% groups at 7 and 14 days of calcification induction (P < 0.05). (6) These results indicate that terpinen-4-ol can inhibit the growth of Staphylococcus aureus and Streptococcus mutans and promote the proliferation, differentiation and mineralization of MC3T3-E1 cells.
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    Preparation and in vitro validation of nanotransmission system for accurate targeting of CD24 high-expression triple negative breast cancer cells
    Zhou Yuqing, Li Jinsui, Chen Yu, Chen Maoshan, Hou Lingmi, Wang Dongsheng, Pu Lulan, Deng Shishan, Zhou Fangfang
    2023, 27 (25):  4013-4019.  doi: 10.12307/2023.452
    Abstract ( 307 )   PDF (1251KB) ( 33 )   Save
    BACKGROUND: The combination of nanotechnology and medicine has opened up a new path in the field of selective targeting and tumor treatment. Through the application of nano carriers, the targeted delivery and stability of loaded drugs are ensured, and the cell uptake and biocompatibility are enhanced.
    OBJECTIVE: To prepare a glutathione and pH double-responsive CD24 aptamer-modified nanodrug delivery system PC (coBP) Ca for ferroptosis agonists Erastin and biplasmids and to investigate its precise targeting and feasibility of CD24 highly expressed cells in triple negative breast cancer in vitro. 
    METHODS: PEG-CAPDB underwent multiple polymerization reactions to form a nanosphere skeleton called: COOH-PEG-CPADB-[co BMA co PDSMA], and then PC (coBP) formation by self-assembling synthesis of the internally loaded ferroptosis agonist Erastin, 1-2M2ge compound, NF2 knockout plasmid and YAP overexpressed plasmid. SELEX technology was used to screen CD24 aptamers to further modify PC (CoBP). Nano-drug delivery system PC (coBP) Ca was eventually formed. The effects of CD24 aptamer modification on the surface of PC(coBP)Ca, sensitivity to glutathione and pH, phagocytosis and targeting properties of immune cells escaping, lysosomal escaping phagocytosis and drug burst release properties, and phagocytosis of phagocytes were detected. 
    RESULTS AND CONCLUSION: The average particle size of PC (coBP) Ca was (141.11±13.43) nm. The average polydispersity index was (0.353±0.074). The average Zeta potential showed good dispersibility. The average drug loading of Erastin was (23.34±2.45)%. The encapsulation rate of PC (coBP) Ca was (90.24±3.11)%, and the 4-hour release was about 90% under the dual response system of glutathione and pH, which could effectively evade immune cell phagocytosis to accurately target CD24 highly expressed triple negative breast cancer, escape lysosomes, then achieve drug release, which activates the ferroptosis pathway and promotes phagocyte phagocytosis. The successful synthesis of nano-delivery system PC (coBP) Ca has the characteristics of precision, effectiveness, safety and low toxicity, and is expected to become a CD24 high-expression cell-targeted nano-delivery system in triple negative breast cancer.
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    Neurotrophic factor 3-chitosan carrier induces neural stem cells to differentiate into neuronal subtypes and their electrophysiological properties
    Zhang Boya, Duan Hongmei, Bai Tianyu, Hao Fei, Hao Peng, Zhao Wen, Gao Yudan, Li Xiaoguang, Yang Zhaoyang
    2023, 27 (25):  4020-4027.  doi: 10.12307/2023.081
    Abstract ( 286 )   PDF (3596KB) ( 49 )   Save
    BACKGROUND: Previous studies have confirmed that the neurotrophic factor 3-chitosan carrier can support the survival and proliferation of neural stem cells, and can efficiently induce neural stem cells to differentiate into neurons. 
    OBJECTIVE: To observe the effects of neurotrophic factor 3-chitosan carrier on neuronal development and its electrophysiological properties at various stages of development and the subtypes of mature neurons. 
    METHODS: Passage 3 spinal cord neural stem cells of neonatal rats were collected and cultured in four groups. The blank control group was added with neural stem cell culture medium. Chitosan group was added with neural stem cell culture medium containing chitosan. Neurotrophic factor 3 group was added with neural stem cell medium containing neurotrophic factor 3. Neurotrophic factor 3-chitosan group was added with neural stem cell medium containing neurotrophic factor 3-chitosan carrier. Immunofluorescence staining was performed to observe the development of neurons at various stages. The changes in electrophysiological properties during neural stem cell development were evaluated by whole-cell patch-clamp technology. Interneuron subtypes were visualized by immunofluorescence staining 21 days after neural stem cell differentiation. 
    RESULTS AND CONCLUSION: (1) Immunofluorescence staining for Nestin, DCX, Tuj1 and MAP2 showed that the neurotrophic factor 3-chitosan carrier maintained the homeostasis of the neural stem cell pool and promoted neuronal maturation by accelerating the developmental process of neuroblasts. (2) Whole-cell patch-clamp technology results demonstrated that the neurotrophic factor 3 and neurotrophic factor 3-chitosan promoted cell membrane function and the maturation of ion channels on the cell membrane early in development. However, only neurotrophic factor 3-chitosan can maintain this advantage to the middle and late stages of development, that is, 7-14 days after differentiation. (3) Immunofluorescence staining exhibited that after 21 days of neural stem cell differentiation, mature neurons in the neurotrophic factor 3-chitosan group could express the motor neuron specific marker HB9, V1 type interneuron FOXP1, V2 type interneuron specific marker LHX3, and regulate a specific marker VGLUT3 that regulates mechanical pain sensory interneurons. (4) These results have verified that the neurotrophic factor 3-chitosan carrier can promote the development of neural stem cells to neuroblasts, and the function of the cell membrane and the maturation of ion channels on the cell membrane in the early stage of development to a certain degree, and can induce the diversification of mature neuronal subtypes.
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    In vitro experiment of composite nanofibrous periosteum to promote vascularization and osteogenic mineralization
    Wang Wenbo, Xu Jingzhi, Wu Liang, Xi Kun, Xin Tianwen, Tang Jincheng, Gu Yong, Chen Liang
    2023, 27 (25):  4028-4037.  doi: 10.12307/2023.163
    Abstract ( 255 )   PDF (3221KB) ( 39 )   Save
    BACKGROUND: Periosteum is essential for the development, remodelling and integrity of bone. Therefore, designing a biomimetic periosteum with high biocompatibility, biodegradability and strong osteogenic ability from the perspective of structure and function is of great significance to the research and development of bone defects.
    OBJECTIVE: To investigate the physicochemical characteristics, biocompatibility and in vitro pro-vascularisation and bone differentiation capabilities of fibrous bone membranes using composite nanofibrous bone membranes loaded with black phosphorus nanosheets and vascular endothelial growth factor (VEGF).
    METHODS: Black phosphorus (BP) was stripped into black phosphorus nanosheets by liquid phase exfoliation. VEGF and black phosphorus nanosheets were encapsulated in aqueous solution of sodium hyaluronate to form BP@VEGF to form microsoluble particles, which were added to dichloromethane solution containing L-polylactic acid and mixed well. N,N-dimethylformamide was added to form a mixed solution to obtain nanocomposite artificial fibrous bone membrane by electrostatic spinning technique (denoted as PLLA-BP@VEGF). In the same way, simple L-polylactic acid fibrous periosteum (denoted as PLLA), L-polylactic acid-black phosphorus fibrous periosteum (denoted as PLLA-BP), and L-polylactic acid-VEGF fibrous periosteum (denoted as PLLA-VEGF) were prepared. Bone marrow mesenchymal stem cells were co-cultured with the above four groups of fibrous periosteum. The cell biocompatibility of fibrous periosteum was detected by live-dead fluorescent staining, CCK-8 assay and cell morphological adhesion experiments. The osteogenic properties of fibrous periosteum were detected by alkaline phosphatase staining, alizarin red staining, osteocalcin immunofluorescence staining and osteogenesis-related gene PCR. Taking human umbilical vein endothelial cells as the experimental object, the angiogenic ability of the fibrous periosteum of the four groups was detected by angiogenic experiment.
    RESULTS AND CONCLUSION: (1) Live/dead fluorescent staining and CCK-8 assay showed that bone marrow mesenchymal stem cells could proliferate and survive well on the fibrous periosteum of the four groups, among which the PLLA-BP@VEGF group had the largest number of living cells. The cell morphological adhesion experiment showed that the bone marrow mesenchymal stem cells on each fibrous periosteum adhered well and spread well. (2) Alkaline phosphatase staining, alizarin red staining, osteocalcin immunofluorescence staining and osteogenesis-related gene detection showed that the fibrous periosteum of PLLA-BP@VEGF group and PLLA-BP group could promote the osteogenic differentiation of bone marrow mesenchymal stem cells. Angiogenesis experiments showed that compared with the PLLA group and the PLLA-BP group, the blood vessels in the PLLA-VEGF group and the PLLA-BP@VEGF group were longer in length; the vessel-like staining structure was network-like; and there were more crossing nodes. (3) The results show that the composite nanofibrous periosteum loaded with black phosphorus nanosheets and VEGF has good biocompatibility, and can promote the osteogenic differentiation ability of bone marrow mesenchymal stem cells and the angiogenic ability of vascular endothelial cells in vitro. 
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    Carbon dot Prussian blue nanoenzyme antioxidative stress delays intervertebral disc degeneration
    Cao Zhipeng, Shi Yu, Li Ke, Lin Wenzheng, Jiang Letao, Bu Wenzhen, Zhu Hai, Du Jianwei, Wang Huihui, Chen Hao
    2023, 27 (25):  4038-4044.  doi: 10.12307/2023.177
    Abstract ( 390 )   PDF (1962KB) ( 63 )   Save
    BACKGROUND: In recent years, oxidative stress has been found to be an important activation mechanism of intervertebral disc degeneration. Nanoparticles with enzyme-like activity have attracted a lot of attention in the study of anti-oxidant stress, but there is little research on delaying intervertebral disc degeneration.
    OBJECTIVE: To construct carbon dot Prussian blue nanoparticles (PEI-600-Fe C-dots Prussian Blue Nanoparticles, CD-PBs), to verify that CD-PBs can eliminate excessive reactive oxygen species, regulate oxidative stress and delay intervertebral disc degeneration in rats by in vitro and in vivo experiments. 
    METHODS: Based on the hydrothermal method, polyethyleneimine was used as carbon source to prepare carbon dots by mixing with citric acid and FeCl3•6H2O, and then Prussian blue was synthesized in situ on its surface to construct CD-PBs. (1) In vitro experiment: SD rat nucleus pulposus cells were extracted and cultured for three generations. Then, H2O2 solution (control group) and CD-PBs +H2O2 solution (experimental group) were added for co-culture, and the cells cultured alone were used as blank controls. After the cells were treated for 24 hours, the level of intracellular reactive oxygen species and mitochondrial membrane potential were detected by fluorescent probes. The mRNA expression levels of type II collagen, aggrecan, matrix metalloproteinase 3 and tumor necrosis factor α were analyzed by real-time quantitative PCR. (2) In vivo experiment: 30 SD rats were randomly divided into three groups. The blank control group did not do any treatment. In the control group, a model of coccygeal intervertebral disc degeneration was established. In the experimental group, CD-PBs solution was injected into the degenerated intervertebral disc space. At 8 weeks after operation, the morphology of intervertebral disc was observed by pathological section. 
    RESULTS AND CONCLUSION: (1) In vitro experiments: The intracellular reactive oxygen species level in the control group was higher than that in the blank control group (P < 0.05). The level of intracellular reactive oxygen species in the experimental group was lower than that in the control group (P < 0.05). The mitochondrial fluorescence intensity of the control group was lower than that of the blank control group (P < 0.05). The mitochondrial fluorescence intensity of the experimental group was higher than that of the control group (P < 0.05). Compared with the blank control group, the mRNA expression of type II collagen and aggrecan decreased in the control group (P < 0.05); the mRNA expression of matrix metalloproteinase 3 and tumor necrosis factor α increased (P < 0.05). Compared with the control group, the mRNA expression of collagen type II and aggrecan in the experimental group increased (P < 0.05); the mRNA expression of matrix metalloproteinase 3 and tumor necrosis factor α decreased (P < 0.05). (2) In vivo experiment: Hematoxylin-eosin staining showed that the height of the intervertebral disc space in the control group was significantly reduced; the arrangement of the annulus fibrosus was disordered; the structure of the nucleus pulposus was destroyed, and the cells and matrix were lost in large quantities. In the experimental group, the height of the intervertebral disc space did not decrease significantly; the nucleus pulposus was partially lost, and the structure of the annulus fibrosus was slightly disordered, which was significantly improved compared with the control group. (3) The results showed that CD-PBs could prevent oxidative stress by removing intracellular reactive oxygen species and delay intervertebral disc degeneration.
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    Application of intraosseous magnesium alloy distractor in vertical bone augmentation of dog alveolar bone
    Wang Shu, Zhao Guiran, Wang Ru, Yao Yusheng, Qu Zhi
    2023, 27 (25):  4045-4050.  doi: 10.12307/2023.461
    Abstract ( 152 )   PDF (1520KB) ( 120 )   Save
    BACKGROUND: Long course of treatment and second operation limit the extensive application of alveolar distraction osteogenesis, and the distractor made by magnesium alloy as a biodegradable metal material can solve the problem of soft and hard tissue defects of alveolar bone. 
    Objective: To explore the feasibility of establishing an experimental dog model of vertical alveolar distraction osteogenesis using the custom-made intraosseous distractor made by magnesium alloy. 
    Methods: Nine adult mongrel dogs were provided. The bilateral mandibular premolars were extracted from experimental dogs to form models of atrophic alveolar ridge. The right mandible was selected as the experimental side and the left side as the control side. After 3 months, an alveolar segmental osteotomy was carried out in the right mandible and one intraosseous vertical distractor was placed. After a 7-day latency period, the alveolar bone was augmented at a rate of 0.5 mm per times, twice a day for 6 days. After a consolidation of 3 months, the dogs were sacrificed to dissect the mandibles for clinical, X-ray, micro-CT and histological examination. The experimental side was compared with the control side.
    Results AND CONCLUSION: (1) Of the nine dogs, one dog died and was replaced. The rest of the experimental dogs obtained the predicted height and the average alveolar ridge was vertically increased for 4.94 mm measured by a vernier caliper as compared with the control side. (2) The X-ray showed that the distraction gap disappeared and the bone density increased. There were obvious cracks on surfaces of the distractor. (3) Histological examination revealed active osteoblasts and trabecular bone structures, as well as partially mature bone tissue. (4) Micro-CT showed that most of trabecular bone had the same distraction direction (P < 0.05); the trabecular thickness and trabecular number slightly increased (P > 0.05), trabecular separation decreased (P < 0.05) and percentage of bone volume (P < 0.05) and bone mineral density increased (P > 0.05) in the experimental side compared with the control side. (5) It is concluded that the custom-made intraosseous distractor made by magnesium alloy can increase the height of atrophy alveolar and obtain a mature new bone, which provides a good theoretical reference for development of alveolar distractor and clinical practice of the technique.
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    Finite element analysis on overerupted maxillary first molar intrusion using clear aligner
    Wang Biqi, Zhang Miaomiao
    2023, 27 (25):  4051-4056.  doi: 10.12307/2023.504
    Abstract ( 330 )   PDF (1242KB) ( 64 )   Save
    BACKGROUND: Intrusion of overerupted posterior teeth with clear aligner for adult patients with different bone densities, orthodontists mostly choose the diaphragm thickness by subjective experience, and finite element analysis is expected to provide a theoretical basis for choosing the appropriate thickness of diaphragms for patients with different bone densities. 
    OBJECTIVE: To analyze the effects of diaphragm thickness and bone density on the intrusion of overerupted maxillary first molar in adult patients using clear aligners using finite element analysis. 
    METHODS: Four groups of finite element models were created based on four bone densities (cancellous bone types I, II, III, and IV) and assembled with three clear aligner models with diaphragm thicknesses of 0.5, 0.75, and 1 mm, respectively. Finite element analysis was then performed using Ansys 2021 software. Clear aligners applied a 0.2 mm intrusion displacement to the maxillary first molar was simulated in each group. The von Mises stress and tooth displacement trends of root, periodontal ligament, alveolar bone of first molar and its adjacent teeth were compared between groups. 
    RESULTS AND CONCLUSION: (1) The von Mises stress distribution of the first molar was the same in all groups, mainly at the root furcation; the second premolar was distributed in the proximal mid-cervical 1/3; the second molar was distributed at the buccal root furcation. (2) The displacement of the first molar and adjacent teeth was close to mesial displacement; the first molar displayed a buccal displacement trend, whereas adjacent teeth displayed a palatal displacement trend. At class II density of alveolar bone, the first molar X- and Y-axis displacement was the smallest, and the Z-axis displacement was the greatest; displacement of adjacent teeth increased with decreasing bone density. In the Z-axis direction, the displacement of the first molar and adjacent teeth was proportional to the thickness of the diaphragm. The smallest displacement was observed in the second premolar 1 mm and second molar 0.5 mm groups in the X- and Y-axis directions. (3) These results concluded that the use of clear aligners to lower the overerupted molars is less likely to cause pericemental fibrosis and root resorption. Decreased bone density does not increase the risk of root resorption. Class II bone density is optimal for molar intrusion. The maximum equivalent stress of the periodontal ligament and alveolar bone is proportional to the thickness of the diaphragm.
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    Expression and significance of pyroptosis associated protein in peripheral tissues with tantalum cage loosening
    Long Zhisheng, Fu Liuxiang, Gong Feipeng, Wen Jiabin, Deng Ying, Min Huan, Deng Zhuan, Chen Gang
    2023, 27 (25):  4057-4062.  doi: 10.12307/2023.414
    Abstract ( 209 )   PDF (1584KB) ( 134 )   Save
    BACKGROUND: The mechanism of how the fusion cage affects its surrounding cells and eventually leads to osteolysis with aseptic loosening after implantation of the tantalum (Ta) fusion device into the intervertebral space remains to be elucidated.
    OBJECTIVE: To explore the effect of pyroptosis in tantalum (Ta) induced intervertebral osteolysis. 
    METHODS: Patients admitted to the Department of Orthopedics, Jiangxi Provincial People’s Hospital from January 2015 to December 2021 were selected in this study. The observation group (n=19) contained the cases of lumbar fusion tantalum cage loosening and revision. The control group (n=11) consisted of autologous bone graft lumbar fusion, internal fixation removal after fusion of other material cages, and degeneration of adjacent segments implanted with tantalum cages requiring extended fixation of the fusion segment. During the operation, the limiting membrane tissue around the cage and around the fusion segment of the two groups was collected for scanning electron microscopy, immunofluorescence staining and qRT-PCR detection. 
    RESULTS AND CONCLUSION: (1) Electron microscopy showed that a large amount of fibrous tissue proliferation was observed around the tantalum (Ta) fusion vessel and within the boundary membrane tissue of the fused segment in the observation group. Meanwhile, irregular particles on tantalum shedding could be observed partially, but fibrous tissue proliferation was not obvious in the control group, and no irregular particles were found. (2) Hematoxylin and eosin staining showed that a large amount of fibrous tissue proliferation with indistinct osteoblasts was observed in the boundary membrane tissue around the fusions and in the fused segments, and osteoblasts were not obvious in the observation group. Fibrous tissue proliferation was not obvious in the limiting membrane tissue of the control group, and osteoblasts were seen distributed around the bone tissue. (3) Immunofluorescence examination showed that the expression of pyroptosis-related proteins GSDMD, NLRP3 and Caspase 1 in the limiting membrane tissue in the observation group was higher than that in the control group (P < 0.05). (4) qRT-PCR assay showed that mRNA expression levels of GSDMD, Caspase 1 and NLRP3 in the observation group were higher than those in the control group (P < 0.05). (5) These results showed that the expression of pyroptosis related proteins (GSDMD, NLRP3, and Caspase 1) was remarkably increased in tantalum (Ta) fusion loosening cases, indicating that pyroptosis was involved in the pathophysiology of tantalum (Ta) induced intervertebral osteolysis.
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    Effect of different retention forms and resins on reattachment stress of anterior teeth with fractured crown based on finite element analysis
    Gao Jian, Liu Dayong
    2023, 27 (25):  4063-4068.  doi: 10.12307/2023.453
    Abstract ( 259 )   PDF (1855KB) ( 37 )   Save
    BACKGROUND: The factors that affect the effect of fractured crown reattachment include the preservation of fractured crown, adhesive resin and retention form, etc. There is no comprehensive study on the effect of retention form and elastic modulus of resin on fractured crown reattachment stress. 
    OBJECTIVE: To study the effect of different retention forms and resins on the central incisor reattachment by three-dimensional finite element analysis.
    METHODS: Based on CT scan data, Mimics software and Geomagic software were used to generate 3D digital model of anterior teeth. SolidWorks software was used to establish four types of retention forms, including direct reattachment, internal dentin groove, overcontour and internal groove. Five types of resins were used to generate 20 ANSYS finite element models. The adhesive shear force, shear stress and resin equivalent stress, and the first principal stress were selected as evaluation indicators through material mechanics analysis.  
    RESULTS AND CONCLUSION: (1) The shear stress distributions of the direct reconnection and the lip-covering retention were similar, and the shear stress peaks were distributed at the junction of dentin and enamel, and concentrated on the left and right sides. The shear stress peak distribution of the dentin internal groove retention was on the left and right sides of the junction between the dentin groove and the section. The shear stress peaks of the internal groove retention form were distributed on the left and right sides of the junction between the groove and the section. (2) The equivalent stress peaks of resin Von Mises of various retention forms were distributed equally in the middle part of the lingual side. The lip surface covering the retention form was filled with resin with less stress, and the farther away from the cross-section, the less stress. (3) The first principal stress peaks of various retention forms were at the boundary of the dentin and enamel where the resin bore greater tensile stress here, and the resin bore greater compressive stress on the lingual side. (4) The retention form had a great influence on the shear force and shear stress of the adhesive, and the elastic modulus only affected the shear stress of adhesive. The retention form had a great influence on the Von Mises stress peak and the first principal stress peak of the resin, and the elastic modulus only affects the first principal stress of the resin. (5) The evaluation indexes of the dentin internal groove retention form are the best, so it is recommended to use the dentin internal groove retention form in clinical practice.
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    Theaflavin-3,3'-digallate alleviates osteogenesis inhibition induced by wear particles in artificial prostheses
    Hou Zhenyang, Sun Yiling, Su Changzheng, Li Zhen, Xu Zhengwen, Li Wenming, Bai Jiaxiang
    2023, 27 (25):  4069-4074.  doi: 10.12307/2023.411
    Abstract ( 242 )   PDF (1735KB) ( 60 )   Save
    BACKGROUND: Theaflavin-3,3'-digallate has shown a good therapeutic effect in animal models of osteoporosis by inhibiting osteoclast formation, but there are few studies on osteogenesis.
    OBJECTIVE: To investigate the effect of theaflavin-3,3'-digallate on periprosthetic osteolysis. 
    METHODS: (1) In vitro test: The MC3T3-E1 cells with good growth status were selected and cultured in four groups. The control group was added with osteogenic differentiation medium; the titanium particle group was added with titanium particles + osteogenic differentiation medium; the low-dose group was added with titanium particles + theaflavin-3,3'-digallate (1 mg/L) + osteogenic differentiation medium; high-dose group was added with titanium particles + theaflavin-3,3'-digallate (10 mg/L) + osteogenic differentiation medium. After 2 weeks of osteogenic induction, alkaline phosphatase staining was performed; after 3 weeks of osteogenic induction, alizarin red staining was performed. (2) In vivo experiment: 32 C57BL/6J mice were randomly divided into 4 groups. The blank control group did not receive any treatment. In the model group, sterile titanium particles were evenly placed on the surface of the skull to establish an osteolysis model. The low-dose group and high-dose group were injected intraperitoneally with 1, 10 mg/(kg·d) theaflavin-3,3'-digallate into osteolysis model mice. The mouse skull was analyzed by micro-CT 2 weeks after operation.
    RESULTS AND CONCLUSION: (1) In vitro experiments: alkaline phosphatase and alizarin red staining showed that titanium particles could inhibit alkaline phosphatase activity and mineralized nodule formation in MC3T3-E1 cells, and theaflavins-3,3'-bisgallate could inhibit the effect of titanium particles and was dose-dependent. (2) In vivo experiments: micro-CT scans showed that titanium particles could induce osteolysis around the skull, and high-dose theaflavin-3,3'-digallate could inhibit the osteolysis caused by titanium particles. (3) The results showed that theaflavin-3,3'-digallate could promote the osteogenic differentiation of MC3T3-E1 and inhibit periprosthetic osteolysis.
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    Lubrication mechanism in articular cartilage and tribological application of biomimetic cartilage materials
    Yi Jiafeng, Liu Yubo, Li Chao, Wang Xing, Chai Wei
    2023, 27 (25):  4075-4084.  doi: 10.12307/2023.501
    Abstract ( 310 )   PDF (1837KB) ( 136 )   Save
    BACKGROUND: Articular cartilage has the most effective lubricated surface known in nature, such as knee, hip joints and so on. Under physiological high pressure, the friction coefficient of articular cartilage is as low as 0.001. Such low friction is indeed essential for normal joint movement. Once the cartilage wears down, it can lead to osteoarthritis. Therefore, it is of great importance to understand the lubrication mechanism of articular cartilage. At the same time, with the in-depth study on the mechanism of joint lubrication, the rapid development of bionic cartilage materials also brings hope for the lubrication between articular cartilage and the treatment of cartilage damage. 
    OBJECTIVE: To investigate the latest research progress of articular cartilage lubrication and tribology of biomimetic cartilage lubrication materials. 
    METHODS: The research data on articular cartilage lubrication and tribology of biomimetic cartilage lubrication materials were searched on the databases of CNKI, PubMed, Semantic Scholar, ScienceDirect and Wiley Online Library by computer. According to the inclusion and exclusion criteria, 60 articles were finally selected for review.
    RESULTS AND CONCLUSION: (1) The lubrication of articular cartilage is not achieved by only a single mechanism, but through the joint participation of multiple mechanisms to achieve efficient lubrication. (2) At present, the main research on cartilage lubrication mechanisms mainly focuses on boundary lubrication and hydration lubrication. (3) The boundary lubrication mechanism model of cartilage lubrication mainly functions through boundary molecule such as hyaluronic acid, lubricin, phosphatidylcholine and so on. (4) Multiple molecules between cartilage promote cartilage lubrication through synergistic action, which also provides a new idea for the design of biomimetic cartilage materials. (5) Biomimetic cartilage materials used for cartilage replacement must have excellent mechanical properties and lubrication properties. At present, biomimetic cartilage materials comprehensively improve the lubrication and mechanical properties of biomedical hydrogels through surface modification and coating, so as to be applied to cartilage lubrication. (6) Biomimetic cartilage materials not only play the role of lubrication, but also can be used as the carriers to realize the purpose of drug delivery, providing a promising idea for the design of more excellent material in the future. At present, most of the biomimetic cartilage materials are at the stage of in vitro experiments or animal models, and there is still a certain distance from clinical application.
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    Role and regulation of macrophages in biomaterial-mediated fibrosis formation
    Deng Moyuan, Peng Kun
    2023, 27 (25):  4085-4092.  doi: 10.12307/2023.541
    Abstract ( 262 )   PDF (924KB) ( 49 )   Save
    BACKGROUND: The foreign body reaction induced by implanted biomaterials leads to the formation of surface fibrosis (also known as implant fibrosis), that is, biomaterials are wrapped by fibrous tissue, making them lose their functionality and producing serious clinical complications, which is a major problem in the field of tissue regeneration and repair. The key cells involved in implant fibrosis are macrophages. However, the effects and mechanism of macrophages on the process of implant fibrosis and the strategy of inhibiting fibrosis remain unclear.
    OBJECTIVE: To review the effects of macrophage polarization and differentiation events on material fibrosis, including fibrogenic signal pathways, and strategies to inhibit biomaterial fibrosis based on specific regulation of macrophages.
    METHODS: The relevant articles up to 2022 were searched on PubMed, Wiley, EBSCOhost, ScienceDirect, and Elsevier databases using English search terms “macrophages, biological materials, fibrosis, foreign body reaction, myofibroblasts, inflammation, regulation, surface topology, mechanical properties, chemical signals”, and 60 articles were finally included for the further analysis.
    RESULTS AND CONCLUSION: (1) Both M1 and M2 macrophages may participate in the formation of biomaterial fibrosis. Maybe strategies that regulate macrophage polarity alone cannot inhibit the formation of fibrosis in biomaterials. (2) As a key cellular event in the regulation of macrophage-mediated biomaterial fibrosis, the differentiation of macrophages into myofibroblasts can induce the expression of marker α-smooth muscle actin, indicating that this process has a direct effect on fibrosis. (3) In terms of the signaling pathway of macrophages promoting fibrosis, the analysis suggests that there may be differences in the signaling pathway of macrophages with different phenotypes. (4) Two main pathways are involved in the regulation of macrophage-induced inflammation using the physical properties of biomaterials. First, based on the biomaterial surface topology, the construction of patterning surface less than 100 nm or the enhancement of surface roughness of biomaterial is expected to reduce macrophage fusion and expression of inflammatory factors, reducing fibrosis caused by macrophages. Second, researchers prefer to design and prepare biomaterials with smaller modulus of elasticity to reduce the stress transfer induced by the implant to the injured tissue, reduce macrophage-induced inflammation, and improve the fibrosis during tissue repair. (5) Regarding the use of chemical signals to regulate the expression of macrophage-induced inflammation, regulatory strategies can be implemented mainly in macrophage-derived inflammatory factors, as well as chemical signals for macrophage recruitment, fusion, and differentiation; therefore, effective use of inhibitors and antioxidants can achieve reverse regulation of transforming growth factor β1, reactive oxygen species, nuclear transcription factor κB, and miRNA-21 through the above pathways, thus delaying fibrosis induced by macrophages.
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    Role and advantages of carbon nanotubes for tissue engineering
    Lyu Jiayi, Yao Qingqiang, Zhu Yishen
    2023, 27 (25):  4093-4100.  doi: 10.12307/2023.551
    Abstract ( 286 )   PDF (1046KB) ( 67 )   Save
    BACKGROUND: In recent years, carbon nanotubes have attracted much attention due to their unique structural and material properties. The researches as tissue engineering materials have gradually deepened, and good effects have been achieved in animals.
    OBJECTIVE: To summarize the characteristics of carbon nanotubes as tissue engineering materials and research progress on the application of carbon nanotubes in tissue engineering applications.
    METHODS: Literature retrieval was conducted in WanFang, CNKI, VIP, Web of Science and PubMed databases. The key words were “carbon nanotubes, composite materials, tissue engineering, tissue repair” in English and Chinese. Finally, 75 articles were included for review. 
    RESULTS AND CONCLUSION: (1) Carbon nanotubes are divided into single-walled carbon nanotubes formed from a single layer of tubular graphene and multi-walled carbon nanotubes composed of multiple concentric tubular graphene layers. By modifying carbon nanotubes and adjusting the concentration, the carbon nanotube composite scaffolds have better electrical conductivity, mechanical properties, biocompatibility and biodegradability. (2) By promoting protein adsorption, regulating electrical signal transduction pathway and mechanical transduction signal pathway, cell proliferation, differentiation, adhesion and other behaviors can be promoted and cell activity can be improved. On the basis of these properties, carbon nanotube composite scaffolds can promote bone remodeling and integration, improve nerve and myocardial function, accelerate defect repair and promote tissue regeneration, without adverse reactions in vivo. (3) Current studies have shown that carbon nanotube composite scaffolds can completely repair segmental bone defects, achieve similar nerve repair effects of autologous transplantation and restore the physiological myocardial conduction velocity of damaged myocardium. Therefore, carbon nanotubes have a great potential as new biomaterials in tissue engineering field. (4) The research of carbon nanotubes in the field of tissue repair is still under the level of in vitro experiment or animal experiments. There are still many difficulties ahead in the development of carbon nanotube composite scaffolds from experimental research to clinical practice, such as toxicological evaluation and effectiveness evaluation of carbon nanotubes, which need to be further improved. The relationships among the diameter, length, purity of carbon nanotubes, the preparation method of composite materials and tissue repair related pathways need to be further investigated. 
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