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08 August 2024, Volume 28 Issue 22 Previous Issue    Next Issue

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Comparison of initial stability of mandibular first molar repaired with different threaded implants under immediate loading Li Xinru, Zhao Wenbo, Ji Yan, Teng Weiwei, Wang Yiming, Zhou Libo 2024, 28 (22):  3445-3450.  doi: 10.12307/2024.538 Abstract ( 227 )   PDF (2715KB) ( 197 )   Save BACKGROUND: The threaded conical implant has a good ability to control micro movements and is conducive to immediate loading. However, the effects of double-threaded conical cylindrical implants and conical cylindrical implants on stress distribution and initial stability of implant-bone interface after immediate loading have not been reported. OBJECTIVE: To investigate the impact of double-threaded conical cylindrical implants and conical cylindrical implants on the biological distribution of the implant and the surrounding bone interface during immediate loading in the mandibular molar region.  METHODS: (1) Three-dimensional finite element analysis: Conical beam CT scans of the mandible and first molar of a volunteer were used to develop a basal model of the mandible. The double-threaded conical cylindrical implants and conical cylindrical implants were assembled with the mandibular models, and an immediate-load (or delayed implantation) implant model (a total of four models) for the first mandibular molar was established. Loads in four directions (100 N): axial, lingual and buccal 45°, mesial and distal, and buccal and lingual, were applied to the central fossa of each model’s crown. Three-dimensional finite element method was used to analyze the implant displacement and the stress distribution at the implant-bone interface. (2) In vitro experiment: With the assistance of the oral implant robot, the double-threaded conical cylindrical implants and conical cylindrical implants were implanted on the same artificial bone pieces, separately, and the immediate load model of immediate implant implantation (or delayed implantation) was established in vitro (a total of four groups of models). Osstell resonance frequency analyzer and SmartPeg sensor were used to measure the implant stability coefficient in four vertical directions: front, rear, left, and right measurements, evaluate the initial stability, and verify the finite element analysis results. RESULTS AND CONCLUSION: (1) The displacement difference between double-threaded conical cylindrical implants and conical cylindrical implants was small when the immediate loading of delayed implantation was applied, but the maximum stress value of conical cylindrical implant-bone interface was greater than that of double-threaded conical cylindrical implant-bone interface. When the immediate loading of immediate implantation was applied, the maximum stress value and the maximum displacement of bone around the implant appeared when the load was applied in mesiodistal direction. The stress value of the conical cylindrical implant reached 298.84 MPa and the maximum displacement was 0.31 mm, both of which were larger than that of the double-threaded conical cylindrical implant. (2) The results of in vitro experiments showed that the stability coefficient of the double-threaded conical cylindrical implant was greater than that of the conical cylindrical implant. (3) Compared with the conical cylindrical implant, the double-threaded conical cylindrical implant has higher initial stability under immediate loading, suggesting that the use of double-threaded conical cylindrical implant should be given priority in clinical immediate loading. Figures and Tables | References | Related Articles | Metrics

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Elastase quantitative analysis of elastin effect on mechanical response of anterior cruciate ligament Zhang Wentian, Deng Yuping, Liu Xiaoyun, Li Caijuan, Wang Mian, Liang Zeyu, Xiong Liang, Huang Gang, Chen Guangxin, Li Zitao, Huang Wenhua 2024, 28 (22):  3451-3456.  doi: 10.12307/2024.473 Abstract ( 264 )   PDF (1394KB) ( 135 )   Save BACKGROUND: The anterior cruciate ligament has unique nonlinear mechanical properties under a complex physiological loading environment. Elastin is an important contributor to the mechanical properties of the anterior cruciate ligament, but its mechanical response to the anterior cruciate ligament under axial tension is not clear. OBJECTIVE: To quantitatively analyze the effect of elastin on the tensile mechanical response of the anterior cruciate ligament. METHODS: Elastase solution and control buffer were prepared. The porcine anterior cruciate ligament samples were prepared into small-size samples and randomly soaked in 0, 0.1, 1.0, 2.0, 5.0, and 10.0 U/mL elastase solution for 6 hours, and other small samples of the same size were soaked in 2 U/mL elastase solution for 0, 1, 3, 6, 9, and 12 hours. To determine suitable soaking conditions for elastin-targeted enzymes and verify the digestive effect, histological staining was used to compare the effects of enzyme treatment on tissue structure and composition. The ligament samples were randomly divided into elastase-treated group and PBS group, and immersed in 2 U/mL elastase solution and PBS buffer for 6 hours, respectively. A mechanical tensile test was performed before and after immersion. RESULTS AND CONCLUSION: (1) The biochemical results showed that being treated in 2 U/mL elastase solution for 6 hours could reduce the elastin content by 31.1%, and had no significant effect on other mechanical-related components in the tissue. (2) The histological results showed that elastase was able to penetrate the tissue, and the loose degree of tissue increased after treatment. (3) In the mechanical results before and after treatment, the mechanical properties of the PBS group decreased significantly, only the low-tension elastic modulus increased significantly and the initial length increased significantly in the elastase-treated group. (4) The intergroup comparison results showed that there was no significant difference between the two groups in pre-treatment, but the low-tension elastic modulus, initial slopes, saturated slopes, and initial length of the elastase-treated group after treatment were significantly higher than those in the PBS group. (5) These results suggest that elastin degradation significantly affects the biomechanical properties of the anterior cruciate ligament and further complements our understanding of the structure-function relationship of the anterior cruciate ligament.  Figures and Tables | References | Related Articles | Metrics

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Preparation and characterization of silk fibroin/bioactive glass composite fiber membrane Wang Lu, Xu Jie, Xia Yijing, Zhang Xinsong, Zhao Bin 2024, 28 (22):  3457-3463.  doi: 10.12307/2024.489 Abstract ( 265 )   PDF (3011KB) ( 159 )   Save BACKGROUND: In the construction of guided bone regeneration membrane with biological function, a single material cannot meet the clinical needs due to its insufficient function, so the composite of multiple materials has become a trend of tissue repair engineering.  OBJECTIVE: To prepare silk fibroin/bioactive glass composite fiber membranes by electrospinning technology, and to characterize the physicochemical properties and biocompatibility in vitro.  METHODS: The solution of electrospinning was prepared by dissolving 0.8 g silk fibroin protein in 10 mL hexafluoro-isopropanol alcohol, and the nanofiber membrane of silk fibroin protein was prepared by electrospinning technology (denoted as SF fiber membrane). 0.1, 0.3, 0.5, and 0.8 g of bioactive glass were added to the electrospinning solution, and the silk fibroin/bioactive glass composite fiber membrane was prepared by electrospinning technology (recorded as SF/1BG, SF/3BG, SF/5BG, and SF/8BG fiber membrane in turn). The physicochemical properties and biocompatibility of five groups of fiber membranes were characterized.  RESULTS AND CONCLUSION: (1) The scanning electron microscopy results showed that nanofibers of the prepared composite membrane were smooth, continuous and uniform and had no beaded structure. There was no obvious adhesion between the silk fibers, and they all showed random arrangement of disordered porous structures. The fiber diameter of the fiber membrane decreased after the addition of bioactive glass. Fourier infrared spectroscopy and X-ray diffraction detection results showed that the chemical structure of silk fibroin protein and bioactive glass in fiber membrane was stable. The water contact angles of SF, SF/1BG, SF/3BG, SF/5BG, and SF/8BG were 105.02°, 72.58°, 78.13°, 79.35°, and 72.50°, respectively. (2) Bone marrow mesenchymal stem cells were inoculated on five groups of fiber membranes. CCK-8 assay results showed that SF/1BG, SF/3BG, and SF/5BG fiber membranes could promote the proliferation of bone marrow mesenchymal stem cells compared with SF and SF/8BG. Live cell/dead cell staining showed that the cell vitality on the surface of the five groups of fiber membranes was better, and the number and distribution of cells on the surface of SF/5BG fiber membrane were more uniform. Rhodamine phalloidin staining and scanning electron microscopy exhibited that compared with SF fiber membrane, the SF/5BG fiber membrane was more favorable to the adhesion of bone marrow mesenchymal stem cells. Bone marrow mesenchymal stem cells were inoculated on the fiber membrane of the five groups for osteogenic induction differentiation, and the alkaline phosphatase activity of the SF/3BG and SF/5BG groups was higher than that of the other three groups (P < 0.05, P < 0.01, P < 0.001). Alizarin red staining showed that the formation of calcium nodules in fiber membrane increased after the addition of bioactive glass, and the formation of calcium nodules in the SF/5BG group was the most. (3) The results show that silk fibroin/bioactive glass composite fiber membrane has good biosafety and biocompatibility. Figures and Tables | References | Related Articles | Metrics

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Antibacterial properties of silver nanoparticle-coated stainless steel prepared via active screen plasma surface modification in vitro Wang Zhaofei, He Guoyun, Tian Fangcan, Li Guangfeng, Cao Zhonghua, Liu Xiangfei 2024, 28 (22):  3464-3471.  doi: 10.12307/2024.486 Abstract ( 299 )   PDF (2687KB) ( 183 )   Save BACKGROUND: Most of the silver coating materials prepared using active screen plasma technology in the past do not involve the nanotechnology field. The formed silver coating is in a “thin film” form, which is coated on the surface of the substrate, and the distribution of silver particles on the surface is uneven. Its long-term antibacterial ability is challenged.  OBJECTIVE: To prepare nano silver coatings capable of being “buried” within stainless steel (SS) substrates using active screen plasma surface modification (ASPSM) and to observe antibacterial activity. METHODS: The nano-silver coating was prepared by ASPSM technique on stainless steel substrate. Three groups of coating samples were prepared by adjusting the bombardment time (1, 2, and 4 hours), which were denoted as 1 h-Ag-ASPSM@SS, 2 h-Ag-ASPSM@SS and 4 h-Ag-ASPSM@SS, respectively. The antibacterial activity of the coatings was analyzed by antibacterial ring test and Gram staining. The antibiotic coating samples of gentamicin combined with vancomycin were prepared by using stainless steel as substrate and were recorded as ACNs. Stainless steel, 2 h-Ag-ASPSM@SS, and ACNs were inserted into Staphylococcus aureus or Pseudomonas aeruginosa suspension, respectively. The long-acting (84 days) antibacterial activity of the samples was analyzed by coating plate method. Bone marrow mesenchymal stem cells were co-cultured with stainless steel, 2 h-Ag-ASPSM@SS, and ACNs, respectively. CCK-8 assay, dead/alive staining, and lactate dehydrogenase activity of cell supernatant were detected. Stainless steel, 2 h-Ag-ASPSM@SS, and ACNs were taken after continuous exposure to Staphylococcus aureus suspension for 12 weeks. The amount of residual viable bacteria on the surface of the material was evaluated by spread plate method. Vancomycin drug sensitive disk method was used to evaluate the resistance of residual live bacteria on the surface of materials. RESULTS AND CONCLUSION: (1) With increasing bombardment time, the diameter of nano silver on the sample surface and the silver content in the coating gradually increased. Among them, the 2 h-Ag-ASPSM@SS exhibited the highest surface silver content while forming uniformly spherical nanoparticles. (2) Antibacterial ring test and Gram staining results demonstrated that compared with 1 h-Ag-ASPSM@SS and 4 h-Ag-ASPSM@SS, the 2 h-Ag-ASPSM@SS exhibited better inhibitory effect on Staphylococcus aureus and pseudomonas aeruginosa. After co-culturing with bacteria for 42 and 84 days, the number of viable bacteria on the spread plate method was significantly lower in the 2 h-Ag-ASPSM@SS group compared to the stainless steel and ACNs groups. After co-culturing with Staphylococcus aureus for 84 days and Pseudomonas aeruginosa for 42 days, the number of viable bacteria on the surface of the eluate from the ACNs group was higher than that of the stainless steel group. (3) CCK-8 assay, live/dead staining and lactate dehydrogenase activity of cell supernatant displayed that 2 h-Ag-ASPSM@SS did not have obvious cytotoxicity. ACNs showed obvious cytotoxicity. (4) After co-culture with Staphylococcus aureus for 12 weeks, the residual viable bacteria on the surface of 2 h-Ag-ASPSM@SS group was less than that of stainless steel group, and the residual viable bacteria on the surface of the ACNs group was more than that of stainless steel group. Compared with the stainless steel group, the sensitivity to vancomycin was significantly decreased in the ACNs group (P < 0.001), and there was no significant change in sensitivity to vancomycin in 2 h-Ag-ASPSM@SS group (P > 0.05). (5) The above results indicate that the silver nanoparticle coated stainless steel greatly improves the deposition efficiency of silver nanoparticles on the stainless steel surface and has long-lasting antibacterial properties and good cell compatibility. Figures and Tables | References | Related Articles | Metrics

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Osteogenic properties of polyacrylamide-modified gelatin methacryloyl grafted titanium alloy scaffold Chu Fuchao, Wang Zhenxin, Zhang Dazhen, Yuan Feng 2024, 28 (22):  3472-3477.  doi: 10.12307/2024.563 Abstract ( 339 )   PDF (2230KB) ( 165 )   Save BACKGROUND: Titanium and its alloys are widely used in orthopedic implants due to their excellent biocompatibility, corrosion resistance, and mechanical properties. However, it has biological inertia itself, cannot provide a good growth environment for osteoblasts, and it is difficult to form good osseointegration. OBJECTIVE: To construct a composite hydrogel material of gelatin methacryloyl and polyacrylamide on the surface of titanium alloy scaffold, and analyze its osteogenic ability in vitro. METHODS: Gelatin methacryloyl was mixed with acrylamide. Crosslinking agent and catalyst were added to synthesize gelatin methacryloyl and acrylamide (Gelma-PAAM) composite hydrogel. The titanium alloy scaffold modified by affinity silane was mixed with the Gelma hydrogel and Gelma-PAAM composite hydrogel to complete the loading (recorded as Ti-Gelma and Ti-Gelma-PAAM, respectively). The swelling ratio and degradation rate of the two hydrogels on the surface of the scaffold were compared. The bonding state between hydrogels and titanium alloy was observed by scanning electron microscope. Rat bone marrow mesenchymal stem cells were inoculated into Ti, Ti-Gelma and Ti-Gelma-PAAM scaffolds, separately. Cell proliferation, adhesion, and osteogenic differentiation were detected. RESULTS AND CONCLUSION: (1) Compared with Gelma hydrogel, Gelma-PAAM hydrogel had higher swelling rate and lower degradation rate. (2) Scanning electron microscope showed that the surface of the two kinds of hydrogels was honeycomb structure. After being combined with porous titanium alloy scaffold, the film was wrapped on the surface of scaffold and filled with pores. Among them, the Gelma-PAAM composite hydrogel coated the scaffold more fully. (3) CCK-8 assay and live/dead fluorescence staining showed that bone marrow mesenchymal stem cells proliferated well after coculture with Ti-Gelma and Ti-Gelma-PAAM scaffolds and maintained high activity. After osteogenic induction culture, alkaline phosphatase activity, calcium deposition, and osteogenic gene expression of cells of titanium alloy scaffold group were the lowest, and alkaline phosphatase activity, calcium deposition, and osteogenic gene expression of cells of Ti-Gelma-PAAM scaffold group were the highest. (4) Phalloidin cytoskeletal staining exhibited that the cells of pure titanium alloy scaffold group and Ti-Gelma scaffold group were sparse and insufficiently extended, while the cells of Ti-Gelatin-PAAM group had the most adequate stretching and the densest filamentous actin. (5) The results show that Gelma-PAAM hydrogel has good biocompatibility and osteogenic ability, and is more suitable for osteogenic modification on the surface of titanium alloy than Gelma hydrogel. Figures and Tables | References | Related Articles | Metrics

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Effect of dura mater on enhancement of cranial osteogenesis in rats An Ran, Shao Guo, Zhang Chunyang 2024, 28 (22):  3478-3483.  doi: 10.12307/2024.534 Abstract ( 230 )   PDF (1218KB) ( 73 )   Save BACKGROUND: The dura mater and skull are physically and functionally related, although there have been few investigations on primary extraction of dura mater and cranial cells, as well as co-culture of the two. The use of primary cells to investigate the influence of the dura mater on the skull is novel, and it is hoped that it may give a theoretical foundation for therapeutic therapy. OBJECTIVE: Rat dura mater and cranial bone cells were retrieved in situ to observe the influence of dura mater on cranial bone proliferation and differentiation, as well as to get a basic knowledge of the involvement of Twist1 in this process. METHODS: The enzyme digestion method was used in conjunction with the tissue block method to extract dural cells and cranial osteoblasts from rats within three days of birth. Immunofluorescence staining was used to identify the extracted cells, and alizarin red staining was used to identify and evaluate cranial osteoblasts and their mineralization ability. After co-culturing dural cells and cranial osteoblasts, real-time PCR was utilized to identify the expression of genes associated to cranial osteoblast proliferation and osteogenesis, as well as Twist1. RESULTS AND CONCLUSION: (1) Morphology: The retrieved dural cells had morphological traits similar to fibroblasts, while the osteoblasts were spindle-shaped. (2) Cell identification: immunofluorescence staining revealed that extracted dural cells expressed high levels of vimentin and cranial osteoblasts expressed high levels of alkaline phosphatase; cranial osteoblasts were stained with alizarin red 28 days after osteogenic induction, and obvious mineralized nodules were observed. (3) Real time PCR detection showed that the co-culture group had higher levels of PCNA, alkaline phosphatase, and RUNX2 mRNA expression than the control group (P < 0.01); however, Twist1 mRNA expression was lower (P < 0.01). (4) The findings showed that the primary extracted cranial osteoblasts had a high mineralization capacity, and that the dura mater was a key factor in promoting cranial growth and development and osteogenic differentiation, with Twist1 playing a key role in this process.        Figures and Tables | Related Articles | Metrics

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3D-printed methacrylated gelatin scaffold loaded with fibroblasts promoting angiogenesis in vitro Sun Hui, , Wang Lijun, Cui Aixin, Li Pingping, , Liu Zhiyi 2024, 28 (22):  3484-3489.  doi: 10.12307/2024.536 Abstract ( 328 )   PDF (1779KB) ( 357 )   Save BACKGROUND: Combining seed cells with 3D bioprinting technology enables the specific construction of various tissues and organs to meet the demands of tissue repair. However, further research is needed on the promotion of angiogenesis in damaged tissues.  OBJECTIVE: By cultivating a 3D scaffold structure of methacrylated gelatin loaded with fibroblasts, obtaining the supernatant, and mixing it in different proportions with a complete culture medium to simulate the cellular microenvironment during tissue repair, this study aimed to explore the role of various cellular microenvironments in promoting angiogenesis in endothelial cells.  METHODS: A methacrylated gelatin scaffold structure loaded with fibroblasts was prepared using an extrusion-based 3D bioprinting process. Hydrogel scaffold extract was prepared and mixed with a complete culture medium in ratios of 1:1, 1:2, and 1:4 to obtain conditioned medium. Mouse embryonic fibroblasts BALB3T3 and human umbilical vein endothelial cells were co-cultured with complete medium (control group) and hydrogel scaffold extract, respectively. Cell proliferation was assessed using the CCK-8 assay and cell viability was analyzed using live/dead staining. Three kinds of conditioned medium and complete medium (control group) were used to co-culture with human umbilical vein endothelial cells for tube formulation assay, vascular genetic testing, and immunofluorescence staining of CD31.  RESULTS AND CONCLUSION: (1) Scanning electron microscopy revealed that the methacrylated gelatin scaffold exhibited a porous structure, and rheological results demonstrated excellent mechanical properties of the hydrogel. CCK-8 assay and live/dead cell staining showed that the hydrogel scaffold extract had no obvious cytotoxicity. (2) Tube formulation assay indicated that the hydrogel showed the total length of cell tubules in 1:1 conditioned medium group was smaller than that in the control group (P < 0.05). There were no statistical differences among the four groups in the number of vascular branches formed by endothelial cells (P > 0.05). (3) qRT-PCR results showed that for vascular endothelial growth factor mRNA expression, the 1:2 conditioned medium group was lower than the 1:1 conditioned medium group on day 1 (P < 0.01). On day 3, the expression level of vascular endothelial growth factor in the 1:2 conditioned medium group was higher than that in the control group (P < 0.01). On day 5, the cytokine expression level in the 1:2 conditioned medium group was significantly higher than that in the other three groups (P < 0.01 or P < 0.000 1). The expression in the 1:1 conditioned medium group was significantly lower than that in the other three groups (P < 0.05 or P < 0.01). On day 1, the expression level of basic fibroblast growth factor in the 1:1 conditioned medium group was significantly higher than that in the control group and 1:4 conditioned medium group (P < 0.01, P < 0.05). The expression was higher in the 1:2 conditioned medium group than that in the control group (P < 0.05). On day 3, the expression levels of cytokines in the 1:4 conditioned medium group was higher than that in the control group (P < 0.05). (4) On day 3, the expression of CD31 in the 1:2 conditioned medium group was higher than that in the control group and the 1:4 conditioned medium group (P < 0.05). (5) The results indicate that the resulting conditioned media can simulate the microenvironment of vascular regeneration after tissue damage, promoting the vascularization process of endothelial cells. The best promotion of vascularization in endothelial cells was observed when the ratio of supernatant to complete culture medium was 1:2. References | Related Articles | Metrics

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Hot spots in study of vascular stent effect and problems in medical quality management: health economics evaluation Li Jialu, Li Xiaomeng 2024, 28 (22):  3490-3495.  doi: 10.12307/2024.443 Abstract ( 226 )   PDF (1394KB) ( 192 )   Save BACKGROUND: Clinical use of vascular stents involves high medical costs, but it may also bring long-term benefits in reducing cardiovascular events and improving the quality of life in patients. Economics evaluation can help decision makers better understand the balance between the cost and benefit of treatment. OBJECTIVE: To analyze the related articles of health economics and discuss the hot spots in the study of the effect and problems of vascular stents in medical quality management. METHODS: The articles concerning health economics evaluation of vascular stents were retrieved from the core set of the Web of Science. The VOSviewer_1.6.19 software was used to make a visualization analysis of the annual publication volume, institutions, countries, keywords, etc. Finally, the research hot spots on the effects and problems of vascular stents were analyzed from the perspective of health economics and medical quality management. RESULTS AND CONCLUSION: (1) 120 articles in English were finally included. In the past 10 years, the highest number of articles published in this field was in 2019, with 10 articles. The institution with the largest number of articles published was Harvard University in the United States with 20 articles, and the country with the largest number of articles published was the United States with 58 articles. (2) Keyword cluster analysis demonstrated that the cost-effectiveness analysis of bare metal stents and drug-eluting stents in coronary disease, the cost-effectiveness analysis of angioplasty stent intervention, and the effect of coronary stents in percutaneous coronary intervention are the research hot spots in the field of health economics evaluation of vascular stent research. (3) In the context of medical quality management, the paper further summarized the research hot spots on the therapeutic effect of vascular stents as follows: long-term effect of vascular stents, safety, drug release mechanism research, personalized therapy, restenosis problems, and stent insertion technology. (4) The results of highly cited literature analysis exhibited that drug-eluting stents release drugs to reduce the risk of vascular restenosis, and the restenosis rate is lower than that of bare metal stents, but the cost is usually higher. Biodegradable stents combine the advantages of bare metal stents and drug-eluting stents, that is, avoiding long-term stent existence and reducing the risk of restenosis, but their cost may be higher, and there may be some complications in the short term, and they are not widely used at present. (5) In addition to the direct stent cost, factors that need to be considered when comparing the cost-effectiveness of vascular stents include the risk and cost of stent re-intervention, the risk and cost of complications, the duration and cost of drug therapy, and the quality of life of patients. Therefore, while the initial cost of drug-eluting and biodegradable stents may be higher than bare metal stents, they may lead to better clinical outcomes in the long term, resulting in a more favorable cost effect. (6) Future research directions should focus on making personalized vascular stent treatment decisions, observing the long-term effect of stent treatment, the impact of the stent on patients’ quality of life, formulating health policies, rational allocation of medical resources, and the establishment of long-term follow-up mechanisms. Figures and Tables | References | Related Articles | Metrics

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Antibacterial performance of cerium oxide nanoenzyme against Escherichia coli Zheng Heishu, Zhang Yingjuan, Wei Yanhua, Huang Hui, Ma Xiangyu, Liao Hongbing 2024, 28 (22):  3496-3501.  doi: 10.12307/2024.485 Abstract ( 519 )   PDF (1196KB) ( 192 )   Save BACKGROUND: The increase in multi-drug resistant bacterial infections has become a major problem in modern healthcare due to the development of bacterial resistance to antibiotics and the development of new antibacterial alternative drug materials is of great importance. OBJECTIVE: To synthesize and perform a series of characterization of a CeO2 nanoenzyme to investigate its biocompatibility and antibacterial properties against Escherichia coli. METHODS: CeO2 nanoenzymes were synthesized using a hydrothermal method. The morphology, product composition, and chemical composition were analyzed using characterization methods such as X-ray diffraction, X-ray photoelectron spectroscopy, Fourier infrared analysis, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The peroxide-mimetic enzyme activity of CeO2 nanoenzymes was characterized using TMB color development assay. The toxic effect of CeO2 nanoenzymes at different concentrations (10, 25, and 50 μg/mL) on mouse fibroblast L929 cells was evaluated using the CCK-8 assay. The antibacterial properties of CeO2 nanoenzymes against Escherichia coli under different conditions were evaluated using the plate coating method. Changes in intra-bacterial reactive oxygen species after treatment with different conditions were detected using a reactive oxygen species detection kit. RESULTS AND CONCLUSION: (1) The morphology of the synthesized CeO2 nanoparticles was rod-shaped, with Ce3+ accounting for 29.87% of the total Ce3+/Ce4+ and an average grain size of 7.4 nm. In a slightly acidic environment containing TMB and pH=5.5, CeO2 nanoenzymes mixed with H2O2 showed excellent peroxidase activity, but did not show peroxidase simulated activity at pH=7.4. (2) There was no statistically significant difference in the toxic effects of CeO2 nanoparticles at various mass concentrations on mouse fibroblast L929 cells. (3) In a slightly acidic environment at pH 5.5, Escherichia coli was inhibited to a certain extent in the presence of CeO2 nanoenzyme alone at a concentration of 10 μg/mL, with a decrease in CFU results of about 0.5 log (P < 0.01); in a slightly acidic environment containing 50 μmol/L H2O2, CeO2 nanoenzyme showed excellent antibacterial effects against Escherichia coli, with a decrease in Escherichia coli CFU results of by about 1.5 log (P < 0.001). After CeO2 nanoenzymes interacted with Escherichia coli, the level of reactive oxygen species in Escherichia coli increased (P < 0.05); after CeO2 nanoenzymes interacted with Escherichia coli together with H2O2, the level of reactive oxygen species in Escherichia coli increased significantly (P < 0.001). (4) The results show that the CeO2 nanoenzymes have good biocompatibility, are inherently antibacterial, and can exhibit peroxidase activity in a slightly acidic environment containing low concentrations of H2O2, and generate reactive oxygen species to kill bacteria, thus showing excellent antibacterial effects. Figures and Tables | References | Related Articles | Metrics

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Physicochemical properties and cytocompatibility of biomimetically precipitated nanocrystalline calcium phosphate granules Chen Mingxue, Niu Jianhua, Lin Haiyan, Wu Gang, Wan Ben 2024, 28 (22):  3502-3508.  doi: 10.12307/2024.487 Abstract ( 313 )   PDF (1756KB) ( 184 )   Save BACKGROUND: Artificially synthesized hydroxyapatite ceramic granules are widely used in clinical practice to repair large-volume bone defects. However, the osteogenic effect of hydroxyapatite ceramic granules prepared by high-temperature sintering is limited by their low degradability and bioactivity.   OBJECTIVE: To prepare biomimetically precipitated nanocrystalline calcium phosphate granules by a novel low-temperature deposition technique, and to characterize their physicochemical properties and cytocompatibility.  METHODS: Biomimetically precipitated nanocrystalline calcium phosphate granules were prepared using a modified supersaturated calcium phosphate mineralization solution and a repeated settling and decantation washing method. Hydroxyapatite bioceramic granules were used as the control. The morphology and phase composition of the granules were characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The specific surface area, porosity distribution, hardness and hydrophilicity of the granules were characterized by BET-N2 method, hardness test, and contact angle test. The adsorption properties of the granules for bovine serum albumin and fetal bovine serum protein were determined by bicinchoninic acid assay. The two kinds of granules or granule extracts were co-cultured with human umbilical cord mesenchymal stem cells, and the cell proliferation was detected by MTT assay.  RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that the surface of the two kinds of particles was slightly rough and accompanied by tiny particles, the surface of the hydroxyapatite bioceramic particles was dense and smooth, and the biomimetically precipitated nanocrystalline calcium phosphate granules were mainly composed of needle/plate crystals with non-uniform nanometer size, and formed a nanopore structure between the crystals. X-ray diffraction and Fourier transform infrared spectroscopy exhibited that compared with hydroxyapatite bioceramic granules, biomimetically precipitated nanocrystalline calcium phosphate granules had smaller crystalline particles, lower crystallinity, and more binding water and carbonic acid groups. Compared with hydroxyapatite bioceramic granules, biomimetically precipitated nanocrystalline calcium phosphate granules had higher specific surface area, better hydrophilicity, lower hardness, and higher protein adsorption capacity. (2) The results of MTT assay showed that the two kinds of granule extracts had no cytotoxicity, human umbilical cord mesenchymal stem cells survived well on the surface of the two kinds of granules, and the biomimetically precipitated nanocrystalline calcium phosphate granules had stronger cell proliferation activity. (3) These findings indicate that compared with hydroxyapatite bioceramic granules, biomimetically precipitated nanocrystalline calcium phosphate granules have better physicochemical properties and cytocompatibility.  Figures and Tables | References | Related Articles | Metrics

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Repair of infected osteochondral defect with sustained release vancomycin three-dimensional scaffold in rabbits Li Xingyu, Zhou Jie, Li Shasha, Zhang Tianxi, Guo Guoning, Yu Anyong, Deng Jiang, Ye Peng 2024, 28 (22):  3509-3516.  doi: 10.12307/2024.488 Abstract ( 267 )   PDF (2353KB) ( 307 )   Save BACKGROUND: A large number of studies have confirmed that tissue engineering scaffolds can almost completely repair osteochondral defects. However, when osteochondral defects are complicated with infection, even after thorough debridement in the early stage, the repair effect of simple osteochondral tissue engineering scaffolds is often unsatisfactory. OBJECTIVE: To prepare fibroin/chitosan/nano-hydroxyapatite scaffold loaded with vancomycin hydrochloride sustained release microspheres, and to investigate the repair effect on infected osteochondral defect in distal femur of rabbit.  METHODS: (1) Vancomycin hydrochloride sustained release microspheres were prepared by emulsified solvent evaporation method. The sustained-release microspheres of different weights (7.5, 10, and 12.5 mg) were mixed with fibroin protein-chitosan nanohydroxyapatite solution, and the scaffolds of fibroin protein/chitosan/nano-hydroxyapatite were prepared by chemical crosslinking method. The porosity, water absorption and expansion rate, hot water loss rate of the scaffolds, and drug sustained-release in vitro were characterized. (2) Forty-five New Zealand white rabbits were randomly divided into blank group, control group, and experimental group, with 15 rabbits in each group. The osteochondral defect and infection model of the distal femur of the right hind limb was established in both groups. The blank group was not treated, and the control group was implanted with fibroin protein-chitosan-nano-hydroxyapatite scaffold. Vancomycin hydrochloride sustained-release microspheres (10 mg) of fibroin/chitosan/nano-hydroxyapatite scaffold were implanted in the defect of the experimental group. The levels of C-reactive protein and leukocytes in blood samples were detected 1 week after operation. At 4, 8 and 12 weeks after operation, the tissue of the operative area was taken for gross observation and pathological observation.  RESULTS AND CONCLUSION: (1) With the increase of sustained-release microspheres content, the porosity of scaffolds decreased, and there was significant difference among groups (P < 0.05). There were no significant differences in the pore size, water absorption expansion rate and hot water loss rate among the three groups (P > 0.05). Vancomycin hydrochloride was released sustainably in vitro for more than 30 days in all three groups of scaffolds. (2) The levels of C-reactive protein and leukocytes in blood samples of the experimental group were lower than those of the blank group and control group (P < 0.05). The repair of gross cartilage in the experimental group was significantly better than that in the blank group and the control group. Hematoxylin-eosin, Masson, Alcian blue and type II collagen immunohistochemical stainings showed that the osteochondral repair effect of the experimental group was significantly better than that of the blank group and the control group at each time point. (3) The results showed that fibroin/chitosan/nano-hydroxyapatite scaffolds loaded with vancomycin hydrochloride sustained-release microspheres could effectively promote the repair of open osteochondral defects. Figures and Tables | References | Related Articles | Metrics

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Preparation and characterization of methacryloylated hyaluronic acid/acellular Wharton’s jelly composite hydrogel scaffold Yuan Xun, Ding Zhengang, Fu Liwei, Wu Jiang, Zheng Yazhe, Zhang Zhichao, Tian Guangzhao, Sui Xiang, Liu Shuyun, Guo Quanyi 2024, 28 (22):  3517-3523.  doi: 10.12307/2024.531 Abstract ( 363 )   PDF (1947KB) ( 270 )   Save BACKGROUND: As tissue engineering brings new hope to the worldwide problem of articular cartilage repair, the construction of light-curing 3D printed hydrogel scaffolds with biomimetic composition is of great significance for cartilage tissue engineering.  OBJECTIVE: To construct a biomimetic methacryloylated hyaluronic acid/acellular Wharton’s jelly composite hydrogel scaffold by digital light processing 3D printing technology, and to evaluate its biocompatibility.  METHODS: Wharton’s jelly was isolated and extracted from human umbilical cord, then decellulated, freeze-dried, ground into powder, and dissolved in PBS to prepare 50 g/L acellular Wharton’s jelly solution. Methylallylated hyaluronic acid was prepared, lyophilized and dissolved in PBS to prepare 50 g/L methylallylated hyaluronic acid solution. Acellular Wharton’s jelly solution was mixed with methacrylyacylated hyaluronic acid solution at a volume ratio of 1:1, and was used as bio-ink after adding photoinitiator. Methylacrylylated hyaluronic acid hydrogel scaffolds (labeled as HAMA hydrogel scaffolds) and methylacrylylated hyaluronic acid/acellular Wharton’s jelly gel scaffolds (labeled as HAMA/WJ hydrogel scaffolds) were prepared by digital light processing 3D printing technology, and the microstructure, swelling performance, biocompatibility, and cartilage differentiation performance of the scaffolds were characterized.  RESULTS AND CONCLUSION: (1) Under scanning electron microscope, the two groups of scaffolds showed a three-dimensional network structure, and the fiber connection of HAMA/WJ hydrogel scaffold was more uniform. Both groups achieved swelling equilibrium within 10 hours, and the equilibrium swelling ratio of HAMA/WJ hydrogel scaffold was lower than that of HAMA hydrogel scaffold (P < 0.05). (2) CCK-8 assay showed that HAMA/WJ hydrogel scaffold could promote the proliferation of bone marrow mesenchymal stem cells compared with HAMA hydrogel scaffold. Dead/live staining showed that bone marrow mesenchymal stem cells grew well on the two groups of scaffolds, and the cells on the HAMA/WJ hydrogel scaffolds were evenly distributed and more cells were found. Phalloidine staining showed better adhesion and spread of bone marrow mesenchymal stem cells in HAMA/WJ hydrogel scaffold than in HAMA. (3) Bone marrow mesenchymal stem cells were inoculated into the two groups for chondrogenic induction culture. The results of qRT-PCR showed that the mRNA expressions of agglutinoglycan, SOX9 and type II collagen in the HAMA/WJ hydrogel scaffold group were higher than those in the HAMA hydrogel scaffold group  (P < 0.05, P < 0.01). (4) These findings indicate that the digital light processing 3D bioprinting HAMA/WJ hydrogel scaffold can promote the proliferation, adhesion, and chondrogenic differentiation of bone marrow mesenchymal stem cells.  Figures and Tables | References | Related Articles | Metrics

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Liposome gel loaded oleic acid promotes the repair of chronic burn wounds Wang Maomao, Zhang Qing, Wu Bowen, Xie Yan 2024, 28 (22):  3524-3531.  doi: 10.12307/2024.524 Abstract ( 310 )   PDF (4328KB) ( 199 )   Save BACKGROUND: Oleic acid can regulate inflammation and immune responses, and has the potential to repair skin wounds. Oleic acid has a short retention time at the lesion. It is prone to self oxidation and deterioration in the air, and suitable drug carriers are needed to fully exert the therapeutic effect of oleic acid.  OBJECTIVE: To investigate the efficacy of oleic acid-liposome gel in the treatment of chronic burn wounds.   METHODS: Oleic acid liposome solution was prepared by thin film dispersion method, and then dissolved in Poloxamer gel matrix to prepare oleic acid-liposome gel. (1) In vitro experiment: Oleic acid-liposome gel solution was prepared by adding different volumes of oleic acid-liposome gel into cell medium (volume ratio: 1:3, 1:9, 1:27, respectively). Alma-blue reagent was used to detect the effects of different concentrations of oleic acid-liposome gel on the proliferation of human keratinocytes and human fibroblasts. Crystal violet staining was used to observe cell morphology. (2) In vivo experiment: The animal model of chronic burn wounds was established by using full-thickness burn of SD rat back skin combined with local subcutaneous injection of epirubicin. The 30 successfully modeled rats were randomly divided into five groups with six rats in each group. The wounds of oleic acid liposome gel group, oleic acid group, liposome gel group, positive control group and negative control group were applied with gauze of oleic acid liposome gel, oleic acid, liposome gel, recombinant human epidermal growth factor gel and normal saline. The dressing was changed once every other day. A total of 16 doses were administered. The wound healing was observed. RESULTS AND CONCLUSION: (1) In vitro experiments: Alma-blue reagent detection and crystal violet staining showed that oleic acid liposome gel solution with volume ratio of 1:9 could promote the proliferation of human keratinocytes and human fibroblasts. (2) In vivo experiment: The wound healing time of the oleic acid liposome gel group was shorter than that of the other four groups (P < 0.01), and the wound healing rate at 4, 8, 12, 16, and 20 days was higher than that of the other four groups (P < 0.01). After administration, hematoxylin-eosin staining showed epithelialization and healing of wounds in all five groups, and the epidermal thickness of oleic acid liposome gel group was the closest to normal skin and better than the other four groups. Immunohistochemical staining showed that the expressions of cytokeratin 10, tumor protein 63, α-smooth muscle actin, collagen I, tumor necrosis factor α, interleukin 6, malonaldehyde, and superoxide dismutase in oleic acid liposome gel group were closest to those in normal skin, and superior to those in other four groups. On days 12 and 32 of administration, the expressions of tumor necrosis factor α, interleukin 6, malondialdehyde, and superoxide dismutase in wound homogenate supernatant in oleic acid liposome gel group were closest to those in normal skin, and superior to those in other four groups. (3) The results showed that oleic acid liposome gel could promote the proliferation of keratinocytes and fibroblasts, reduce inflammation and oxidative stress injury, and promote the healing of chronic burn wounds.  Figures and Tables | References | Related Articles | Metrics

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Performance of 3D-printed polylactic acid-nano-hydroxyapatite/chitosan/doxycycline antibacterial scaffold Liu Yan, Zheng Xuexin 2024, 28 (22):  3532-3538.  doi: 10.12307/2024.529 Abstract ( 398 )   PDF (1348KB) ( 216 )   Save BACKGROUND: Polylactic acid has good biocompatibility and biodegradability, and has become a new orthopedic fixation material. However, the lack of cell recognition signal of this material is not conducive to cell adhesion and osteogenic differentiation, which limits its application in biomaterials.  OBJECTIVE: 3D-printed polylactic acid-nano-hydroxyapatite (nHA)/chitosan (CS) scaffold to evaluate its drug sustained-release and biological properties. METHODS: The porous polylactic acid scaffold (recorded as PLA scaffold) with interporous pores was printed by fused deposition modeling technique, and the scaffold was soaked in dopamine solution to prepare polylactic acid-dopamine scaffold (recorded as PLA-DA scaffold). Nano-hydroxyapatite was immersed in chitosan solution, and then the PLA-DA scaffold was immersed in it to prepare polylactic acid-nano-hydroxyapatite/chitosan scaffold (recorded as PLA-nHA/CS scaffold). The micro-morphology, porosity, water contact angle, and compressive strength of the three scaffolds were characterized. PLA-nHA/CS scaffold loaded with doxycycline (recorded as PLA-nHA/CS-DOX scaffold) was prepared by freeze-drying method, and its drug release was characterized. PLA, PLA-DA, PLA-nHA/CS, and PLA-nHA/CS-DOX scaffolds were co-cultured with MC3T3-E1 cells, separately, to detect cell proliferation and osteogenic differentiation. Staphylococcus aureus suspensions of different concentrations were co-cultured with four groups of scaffolds. The antibacterial performance of scaffolds was detected by inhibition zone test.   RESULTS AND CONCLUSION: (1) Under scanning electron microscopy, the surfaces of PLA and PLA-DA scaffolders were dense and smooth, and nHA particles were observed on PLA-nHA/CS scaffolders. The porosity of PLA, PLA-DA and PLA-nHA/CS scaffolds decreased gradually, and the compressive strength increased gradually. The elastic modulus of PLA-nHA/CS scaffolds met the requirements of cancelous bone. The water contact angle of PLA-DA and PLA-nHA /CS brackets was smaller than that of PLA scaffolds. The PLA-nHA/CS scaffold sustainably released drugs in vitro for 8 days. (2) CCK-8 assay showed that the proliferation of MC3T3-E1 cells was not significantly affected by the four groups of scaffolds. The activity of alkaline phosphatase in PLA-DA group, PLA-nHA /CS group, and PLA-nHA/CS-DOX group was higher than that in PLA group. Alizarin red staining showed that compared with PLA group, the cells in PLA-nHA/CS group and PLA-nHA/CS-DOX group showed higher mineralized water level. (3) Inhibition zone test exhibited that PLA and PLA-DA scaffolds had no antibacterial properties. PLA-nHA/CS scaffolds had certain antibacterial properties. PLA-nHA/CS-DOX scaffolds had super antibacterial properties. (4) The results showed that the PLA-nHA/CS-DOX scaffold had good drug release performance, cell compatibility, osteogenic properties, and antibacterial properties. Figures and Tables | References | Related Articles | Metrics

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Application of strontium polyphosphate with both radiopaque and osteogenic functions in calcium phosphate cement Tang Ziniu, Chu Fengcheng, Wu Kang, Zhang Lin, Bai Yanjie, Lin Xiao, Yang Huilin, Zhou Huan, Liu Huiling, Yang Lei 2024, 28 (22):  3539-3547.  doi: 10.12307/2024.522 Abstract ( 171 )   PDF (2614KB) ( 321 )   Save BACKGROUND: Our previous studies found that adding barium sulfate could improve the mechanical and radiopaque properties of calcium phosphate cement. However, with the degradation of calcium phosphate, the remaining radiopaque agent is difficult to degrade, and the space-occupying and osteoclast effects at the implantation site affect the bone repair process. Therefore, it is necessary to develop a new biodegradable radiopaque material. OBJECTIVE: To discuss the radiopaque ability of bioactive degradable material strontium polyphosphate (SrPP) and its impact on the physicochemical properties and osteogenic effect of calcium phosphate cement. METHODS: (1) Calcium phosphate cement (CPC), starch modified calcium phosphate cement (CPS) and starch modified calcium phosphate cement (20% SrPP-CPN) containing SrPP (20% mass fraction of bone cement powder) were prepared respectively, and the physicochemical properties of the three groups of bone cements were characterized. (2) The three groups of bone cement extracts were co-cultured with rat bone marrow mesenchymal stem cells, respectively, to detect cell proliferation, energy metabolism, and osteogenic differentiation. (3) Bone defects with a diameter of 5 mm were made on each side of the top of the skull of 24 SD rats, and they were randomly divided into control group (without any intervention), CPC group, CPS group, and 20% SrPP-CPN group for intervention, with 6 rats in each group. Relevant tests were performed after 4 and 12 weeks of intervention. RESULTS AND CONCLUSION: (1) Compared with the other two groups of bone cement, 20% SrPP-CPN had enhanced radiopaque ability, increased compressive strength and degradation rate, and prolonged curing time, and 20% SrPP-CPN could release Sr2+ stably during degradation. (2) CCK-8 assay showed that 20% SrPP-CPN did not affect the proliferation of bone marrow mesenchymal stem cells. Cell starvation test (serum-free culture) showed that 20% SrPP-CPN could promote the proliferation of bone marrow mesenchymal stem cells compared with the other two groups of bone cement. Compared with the other two groups of bone cements, 20% SrPP-CPN increased adenosine triphosphate concentration in bone marrow mesenchymal stem cells. Alkaline phosphatase and alizarin red staining showed that 20% SrPP-CPN could promote osteogenic differentiation of bone marrow mesenchymal stem cells compared with the other two groups of bone cement. (3) In the rat skull defect experiment, Micro-CT scanning and histological observation (hematoxylin-eosin and Masson stainings) showed that bone cement in 20% SrPP-CPN group was significantly degraded compared with that in CPC and CPS groups, and a large number of new bone tissues were dispersed in degraded bone cement. Immunohistochemical staining showed that Runx2 protein expression was increased in 20% SrPP-CPN group compared with CPC group and CPS group (P < 0.01). (4) These results show that 20% SrPP-CPN has good radiopaque ability and osteogenic properties.  Figures and Tables | References | Related Articles | Metrics

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Effect of bone cement with different elastic moduli injected into intervertebral space on stress of adjacent upper and lower vertebrae Wang Jianxin, Huo Wentao, Yu Ze 2024, 28 (22):  3548-3554.  doi: 10.12307/2024.527 Abstract ( 225 )   PDF (4086KB) ( 101 )   Save BACKGROUND: In recent years, the treatment method of injecting bone cement into the intervertebral space has been introduced from abroad for the treatment of lumbar recurrent pain caused by lumbar disc degeneration and intervertebral space narrowing; however, some patients had vertebral fractures after treatment; the fracture may occur because the bone cement injected into the intervertebral space has a poor elastic modulus. OBJECTIVE: To analyze the effect of bone cement with different elastic moduli injected into the intervertebral space on the maximum stress of upper and lower vertebrae using a three-dimensional finite element model.  METHODS: A volunteer with normal spine was recruited to obtain CT data. The finite element model of L2-L5 lumbar spine was established using Mimics, Geomagic, SolidWorks, and Ansys. Subsequently, a L3-L4 intervertebral space injection model with different doses (1 mL and 4 mL) of bone cement was established. Four different elastic moduli (1 000, 2 000, 4 000, and 8 000 MPa) were assigned to bone cement at each dose. Pressure and bending moment were applied on the surface of the L2 vertebral body to analyze the stress on the lower surface of the L3 vertebral body and the upper surface of the L4 vertebral body.  RESULTS AND CONCLUSION: (1) In the case of the same amount of bone cement injection, as the elastic modulus of bone cement increased, the stress on the lower surface of L3 vertebral body and the upper surface of L4 vertebral body increased. Among them, the bone cement with an elastic modulus of 1 000 MPa had the least effect on the lower surface of L3 vertebral body and the upper surface of L4 vertebral body. Bone cement with elastic modulus of 8 000 MPa had the greatest effect on the lower surface of L3 vertebral body and the upper surface of L4 vertebral body. Bone cement with different elastic moduli had little effect on the motion range of the whole lumbar spine. (2) The results indicate that injecting bone cement with lower elastic modulus while meeting treatment requirements can reduce the risk of postoperative fractures.  Figures and Tables | References | Related Articles | Metrics

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Preparation and performance of gelatin modified by methacrylic anhydride/treated dentin matrix bioactive scaffolds Cheng Mengke, Yang Dujuan, Liu Jia 2024, 28 (22):  3555-3560.  doi: 10.12307/2024.537 Abstract ( 239 )   PDF (1796KB) ( 180 )   Save BACKGROUND: Pulp regeneration has been a hot and difficult research topic in recent years, and the construction of composite bio-scaffolding materials provides new ideas and methods for pulp regeneration.  OBJECTIVE: To observe the effect of freeze-dried gelatin modified by methacrylic anhydride/treated dentin matrix bioactive scaffolds on proliferation, migration, and osteogenic differentiation of human dental pulp stem cells.  METHODS: The mass ratios of gelatin modified by methacrylic anhydride and treated dentin matrix at 2:1, 1:1 and 1:2 were obtained by dispersing different masses of treated dentin matrix into gelatin modified by methacrylic anhydride solution. The gelatin modified by methacrylic anhydride/treated dentin matrix bioactive scaffolds were prepared by vacuum freeze-drying. The microstructure, water absorption, and mechanical properties of the scaffolds were measured. Human dental pulp stem cells were cultured with different mass ratios of scaffold extract and DMEM (control group) to detect cell proliferation and migration. Human dental pulp stem cells were cultured with different mass ratios of scaffold extract + osteogenic induction solution and DMEM + osteogenic induction solution (control group), and their osteogenic ability was analyzed by alkaline phosphatase staining. RESULTS AND CONCLUSION: (1) Under scanning electron microscopy, the scaffolds of the three groups all had porous structures. The porosity of the scaffolds increased with the increase of treated dentin matrix quality, and there was significant difference between the two groups (P < 0.05). The water absorption of scaffolds increased with the increase of treated dentin matrix mass, and there was significant difference between groups (P < 0.05). The compressive strength and shear strength of the scaffold increased with the increase of the mass of treated dentin matrix. (2) CCK-8 assay showed that after 3, 5, and 7 days of culture, the cell proliferation absorbance values in the 2:1, 1:1, and 1:2 scaffold groups were higher than those in the control group (P < 0.05). The cell proliferation absorbance values increased with the increase of treated dentin matrix mass in the scaffold (P < 0.05). The cell scratch test showed that the cell migration rate in the 2:1, 1:1, and 1:2 scaffold groups was higher than that in the control group (P < 0.05), and the cell migration rate increased with the increase of treated dentin matrix mass in the scaffold (P < 0.05). (3) Alkaline phosphatase staining showed that the osteogenic differentiation ability of cells in the 2:1, 1:1, and 1:2 scaffold groups was stronger than that in the control group, and the osteogenic ability of cells was enhanced with the increase of treated dentin matrix mass in the scaffold. (4) The results showed that the scaffold with a mass ratio of 1:2 between gelatin modified by methacrylic anhydride and treated dentin matrix was the most suitable for the proliferation and differentiation of dental pulp stem cells.  Figures and Tables | References | Related Articles | Metrics

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Biological and physicochemical properties of bioactive ion modified brushite cements Zeng Cheng, Yu Huanhuan, Gong Yukang, Wang Chenhao, Zhang Yinen, Gao Wenshan 2024, 28 (22):  3561-3568.  doi: 10.12307/2024.490 Abstract ( 414 )   PDF (2434KB) ( 186 )   Save BACKGROUND: As a bone replacement and filling material, calcium phosphate stone bone cement has good biocompatibility, bone conductivity, and other advantages, especially its better biodegradability compared to other calcium phosphate bone cements. It has important application value in bone repair. However, due to its limitations such as insufficient mechanical properties, fast solidification reaction, and poor injection performance, it is currently only suitable for the repair of non weight-bearing bone. OBJECTIVE: To explore the modification of brushite cements with bioactive ions (metal and non metal ions) to expand its application range. METHODS: The author used PubMed, ScienceDirect, CNKI, and WanFang to search the literature published between 2018 and 2023 with the search terms “metal ion, iron, copper, strontium, magnesium, zinc, non-metal ion, modification, bone, brushite cements” in Chinese and “metal ion, iron, Fe, copper, Cu, strontium, Sr, magnesium, Mg, zinc, Zn, non-metal ion, modification, bone, brushite cements” in English. After reading titles and abstracts, the articles were initially screened, and irrelevant and duplicate articles were excluded. Finally, 64 articles were included for review. RESULTS AND CONCLUSION: (1) Bioactive ions affect the hydration process of calcium phosphate bone cement. Different ions are substituted by ions and incorporated into the crystal structure of calcium phosphate bone cement, changing the crystal morphology of the cement and causing changes in physical and chemical properties such as setting time, injectability, and compressive strength. (2) Ionic modified calcium phosphate bone cement produces different ion release effects due to different crystal structures. Different types of ions have properties such as promoting angiogenesis/osteogenesis, antibacterial, anti-tumor, etc. In addition, calcium phosphate bone cement has good biodegradability, which has great advantages for the performance of various ions. (3) The physicochemical properties of calcium phosphate bone cement modified with different ions are as follows: iron, copper, strontium, magnesium, zinc, silver, and cobalt can prolong the setting time. Strontium, and magnesium can improve injection performance. Copper, strontium, magnesium, silver and silicon can enhance compressive strength. The ions that can simultaneously improve the three physical and chemical properties of calcium phosphate bone cement include strontium and magnesium. Good physical and chemical properties are a prerequisite for clinical application, so improving the setting time, injectability, compressive strength, and other properties of calcium phosphate bone cement with ions is of great significance for the research and application of bone cement. (4) The biological properties of calcium phosphate bone cement modified with different ions are as follows: copper, strontium, magnesium, zinc, cobalt, lithium, selenium, and silicon have promoting angiogenesis/osteogenic effects. Iron, copper, magnesium, zinc, and silver have antibacterial properties. Magnesium ions have anti-inflammatory properties. Copper and selenium have anti-tumor properties. (5) In summary, magnesium ions can improve the setting time, injectability, and compressive strength of calcium phosphate bone cement, while also promoting neovascularization/osteogenesis, antibacterial properties, and have good application prospects for the treatment of bone defects with concurrent infections. In addition, copper also has anti-tumor properties, so copper ions have great potential in the treatment of bone defects caused by infections and tumors. However, relevant research is still in the basic research stage, and the effects of different ion doping concentrations and synthesis conditions on the physicochemical properties of calcium phosphate bone cement need to be further explored. At the same time, the impact of biological properties also needs to be studied and observed for a longer period of time.  Figures and Tables | References | Related Articles | Metrics

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Application of bioelectric effect materials in design of bone tissue engineering scaffolds Xi Hongzhong, Liu Xin, Sun Guangquan, Du Bin, Yuan Xinwei, Huang Yixuan, Guo Mingbin, Mai Jianbin 2024, 28 (22):  3569-3575.  doi: 10.12307/2024.521 Abstract ( 360 )   PDF (1201KB) ( 436 )   Save BACKGROUND: Bone has bioelectric effects. However, bone defects can lead to loss of endogenous bioelectricity in bone. The implantation of bone tissue engineering scaffolds with bioelectric effect into bone defects will replenish the missing electrical signals and accelerate the repair of bone defects. OBJECTIVE: To introduce the bioelectric effect of bone tissue and expound the repair effect of electrical stimulation on bone defects, summarize the research progress of bioelectric effect applied to bone tissue engineering, in order to provide new ideas for the research of bone tissue engineering.  METHODS: Relevant articles were searched on CNKI, WanFang, PubMed, Web of Science and ScienceDirect databases, using “bioelectrical effect, bioelectrical materials, electrical stimulation, bone tissue engineering, bone scaffold, bone defect, bone repair, osteogenesis” as the English and Chinese search terms. Finally, 87 articles were included for analysis. RESULTS AND CONCLUSION: (1) Bioelectrical effect combined with ex vivo electrical stimulation to design bone tissue engineering scaffolds is an ideal and feasible approach, and the main materials involved include metallic materials, graphene materials, natural bio-derived materials, and synthetic biomaterial. At present, the most widely used conductive material is graphene material, which benefits from its super conductivity, large specific surface area, good biocompatibility with cells and bones, and excellent mechanical properties. (2) Graphene materials are mainly introduced into the scaffold as modified materials to enhance the conductivity of the overall scaffold, while its large surface area and rich functional groups can promote the loading and release of bioactive substances. (3) However, there are still some major challenges to overcome for bioelectrically effective bone tissue engineering scaffolds: not only electrical conductivity but also the overall performance of the bracket needs to be considered; lack of uniform, standardized preparation of bioelectrically effective bone tissue engineering scaffolds; extracorporeal electrical stimulation intervention systems are not yet mature enough; lack of individualized guidance on stent selection to enable the selection and design of the most appropriate stent for patients with different pathologies. (4) When designing conductive scaffolds, researchers have to deeply consider the comprehensive effects of the scaffolds, such as biocompatibility, mechanical properties, and biodegradability. This combination of properties can be achieved by combining multiple materials. (5) Beyond that, clinical translation should be the ultimate consideration for conductive stent design. On the basis of evaluating the safe current threshold for electrical stimulation to act on the human body and facilitate the repair of bone defects, animal experiments as well as basic experiments are designed and then applied to the clinic to achieve the ultimate goal of applying bioelectrical effect bone tissue engineering scaffolds in the clinic. Figures and Tables | References | Related Articles | Metrics

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Application of gelatin methacryloyl as a three-dimensional cell culture scaffold in bone tissue engineering Wang Sainan, Wang Xiaofei, Zhang Li 2024, 28 (22):  3576-3482.  doi: 10.12307/2024.525 Abstract ( 526 )   PDF (1107KB) ( 349 )   Save BACKGROUND: The treatment of bone defects has always been a pressing clinical challenge for medical practitioners. The use of gelatin methacryloyl for three-dimensional extracellular cultivation offers a promising direction for the treatment of extensive bone defects. OBJECTIVE: To review the research progress of gelatin methacryloyl as a three-dimensional cell culture scaffold in bone tissue engineering, aiming to provide further references for clinical bone defect repair. METHODS: Computerized searches were conducted on the CNKI and PubMed databases for articles published from January 1986 to August 2023. The search terms in Chinese and English were “bone defect, bone tissue engineering, biomaterial scaffold, hydrogel, photocrosslinked hydrogel, gelatin methacryloyl, three-dimensional culture, cell culture” and “bone defect, bone tissue engineering, biomaterial scaffold, hydrogel, gelatin methacryloyl, three-dimensional culture, cell culture”, respectively. Finally, 68 articles were included for review and analysis. RESULTS AND CONCLUSION: (1) When compared to two-dimensional culture techniques, three-dimensional culture can construct a three-dimensional space under aseptic conditions, more effectively simulating the in vivo environment. It provides cells with the appropriate temperature, pH, and sufficient nutrients, allowing cells to grow and proliferate normally outside the body while maintaining their regular structure and function, offering unique advantages. (2) In the realm of bone tissue engineering, hydrogels stand out as the preferred choice for biomaterial scaffolds. Their excellent biocompatibility, degradability, and inherent three-dimensional network structure make them invaluable in bone regeneration studies. (3) The physical and biological properties of gelatin methacryloyl are influenced by factors such as concentration, light exposure duration, type of photoinitiator, and the overall reaction system. These properties can affect cell adhesion, growth, and proliferation, and even the morphology and function of cells. (4) Gelatin methacryloyl, recognized for its excellent biocompatibility, tunable physical properties, injectability, and photosensitivity, has been extensively used in three-dimensional cell encapsulation, three-dimensional bioprinting, and stereolithography techniques based on digital light processing in three-dimensional cell culture systems. (5) Utilizing a range of composite gelatin methacryloyl in three-dimensional cell culture can significantly promote vascularization and bone regeneration, paving the way for enhanced clinical solutions to bone defects. (6) At present, there is a noticeable gap in standardized guidelines concerning the sources, synthesis methods, and safety of gelatin methacryloyl. It is crucial to intensify research efforts to optimize gelatin methacryloyl’s application in the three-dimensional cell culture field. Figures and Tables | References | Related Articles | Metrics

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Potential and advantages of metal organic frameworks-based hydrogel materials for repairing soft and hard tissues Zhao Zipei, Wang Xu, Zhao Weifeng, Pei Xibo 2024, 28 (22):  3583-3590.  doi: 10.12307/2024.526 Abstract ( 533 )   PDF (1377KB) ( 514 )   Save BACKGROUND: Due to the mechanical properties, unstable drug release, single function and other problems of pure hydrogel materials, in recent years, researchers have prepared a variety of metal organic frameworks-based hydrogel materials by introducing metal organic frameworks into hydrogel, and showed great potential in the field of soft and hard tissue regeneration.  OBJECTIVE: To classify the metal organic frameworks-based hydrogel materials based on how metal organic frameworks enhance the properties of hydrogel and further summarize its recent research in the field of soft and hard tissue regeneration, in order to provide ideas and theoretical supports for the subsequent in-depth research on synthesis mechanism and clinical application of the composite material. METHODS: Using “metal organic frameworks, hydrogels, tissue engineering, tissue, bone regeneration, bone, wound” as English and Chinese search terms, we searched Web of Science, PubMed, CNKI, and Wanfang databases. The search period ranged from January 2000 to August 2023. By reading the titles and abstracts, the repetitive studies and unrelated literature of Chinese and English literature were excluded. After the literature quality evaluation, 73 articles were included for review.  RESULTS AND CONCLUSION: (1) Metal organic frameworks-based hydrogel materials effectively solve the problems of poor mechanical properties, unstable drug release and single function of pure hydrogel. (2) Metal organic frameworks enhance the capacity of repair and regeneration by strengthening the cross-linking of hydrogel, the drug delivery capacity of hydrogel and the multifunction of hydrogel. (3) In terms of hard tissue repair, it has shown good repair effects in animal models of diseases such as bone defects, osteoarthritis, and cartilage defects, suggesting potential application prospects in clinical repair. (4) In terms of soft tissue regeneration, it has the capacities of hemostasis, antibacterial, inflammatory state regulation, oxidative stress state regulation, promoting angiogenesis and other functions, effectively improving the microenvironment of various complex wounds and promoting soft tissue regeneration. (5) Although metal organic frameworks-based hydrogels have many excellent properties, they are still in the initial stage and there are some urgent problems to be solved in the process of clinical transformation, such as the cytotoxicity of metal organic frameworks and large-scale synthesis of metal organic frameworks. (6) With further research, metal organic frameworks-based hydrogels have broad application prospects in the field of soft and hard tissue repair. Figures and Tables | References | Related Articles | Metrics

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Biomechanical characteristics of “All-on-4” concept analyzed by three-dimensional finite element method Lu Jing, Li Ying, Meng Maohua, Wang Huan, Shu Jiayu, Li Wenjie, Luo Yuncai, Dong Qiang 2024, 28 (22):  3591-3596.  doi: 10.12307/2024.481 Abstract ( 274 )   PDF (954KB) ( 235 )   Save BACKGROUND: With the increasing demand for edentulous jaw restoration, “All-on-4” concept is widely used. The load transfer mode of implant is different from that of natural tooth. The three-dimensional finite element analysis can study the stress distribution of implants and surrounding bone tissues under functional loading. On this basis, it provides research methods for finding suitable implant materials, optimizing implant geometry, and designing clinical surgical protocols.  OBJECTIVE: To review researches related to three-dimensional finite element analysis in “All-on-4” concept. METHODS: Relevant literature published from 2003 to 2023 was searched in CNKI and PubMed databases with the search terms of “finite element method; All-on-4; edentulous; biomechanics” in Chinese and English. Finally, 65 articles were included for review. RESULTS AND CONCLUSION: (1) In the case of insufficient horizontal bone mass, we can choose to apply narrow diameter implants, but we need to pay attention to the effect of the presence of the cantilever on the stress distribution and reduce the risk of failure. (2) The “All-on-4” concept reduces the stress distribution of bone by tilting the distal middle implant, but the ideal angle of the distal implant tilt in different jaw types requires further study. (3) The presence of cantilevers increases the risk of implant failure, and keeping the cantilever length/AP distance ratio at 0.9 helps to minimize mechanical complications. (4) When a framework is made of a material with a lower elastic modulus, the stress on the framework itself will be smaller, but it will increase the stress on the implant, prosthetic screw, abutment and peri-implant bone. On the contrary, when a material with a higher elastic modulus is used, it can reduce the stress on the prosthetic components, implants and peri-implant bone in the restoration, but the stress on the framework itself is higher. (5) The “All-on-4” concept allows for a better mechanistic balance, but requires the development of a long-term, effective treatment program that is tailored to the patient’s specific situation. (6) Proper occlusal scheme is the key to the success of implant treatment, and there is no difference between canine-guide occlusion and group function occlusion in terms of the longevity of the restoration. However, there are many factors that influence occlusal design, and further in vitro experiments as well as a number of clinical studies are needed to explore the ideal occlusal design of the “All-on-4”. Figures and Tables | References | Related Articles | Metrics

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Polymer-based antibiotic sustained-release carrier in treatment of chronic osteomyelitis Ilham • Maimaitiabudula, Huang Xiaoxia, Li Luyao, Teng Yong 2024, 28 (22):  3597-3602.  doi: 10.12307/2024.477 Abstract ( 286 )   PDF (972KB) ( 283 )   Save BACKGROUND: In the treatment strategy of chronic osteomyelitis, the local antibiotic slow-release system has attracted much attention in the clinic due to the long-term release of effective concentrations of antibiotics to control the infection, and at the same time, the ability to repair bone defects caused by debridement.  OBJECTIVE: To summarize the research status of antibiotic sustained-release carriers prepared from biodegradable polymer-based materials for the treatment of osteomyelitis, and analyze the limitations and challenges. METHODS: Chinese and English key words were “polymer, composite material, osteomyelitis, infectious bone defect, drug delivery systems, antibiotic sustained-release system, 3D printing”. Relevant articles were searched in PubMed, Web of Science, CNKI, and WanFang databases from January 2015 to August 2023. 4 351 articles were obtained in the initial examination, and 87 articles were analyzed after screening.  RESULTS AND CONCLUSION: Polymer-based materials have been widely studied in the preparation of antibiotic sustained-release carriers due to their good biocompatibility, biodegradability, thermal stability, and easy processing. However, the antibiotic slow-release carrier composed of a single polymer material cannot meet the standard of infectious bone defect repair materials due to the lack of biomechanical properties. The organic-inorganic composite material carrier, which simulates the formation of natural bone tissue structure, is expected to meet this standard. 3D printing technology can precisely control the size, geometry, and spatial distribution of the interconnecting pores of the carrier, and can load the effective concentration of antibiotics to achieve controlled release. The polymer material is the most suitable for 3D printing because of its good thermal stability and plasticity. Therefore, the author believes that on the basis of new biodegradable organic-inorganic composite materials and combined with 3D printing technology, the material-structure-function integrated composite antibiotic slow-release carrier to simulate the extracellular matrix microenvironment is expected to become a novel research direction in the treatment of chronic osteomyelitis. Figures and Tables | References | Related Articles | Metrics

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Research and development of nanoparticles with active targeting ability in nonneoplastic kidney disease Liu Chang, Li Linhua, Fu Ping 2024, 28 (22):  3603-3608.  doi: 10.12307/2024.532 Abstract ( 412 )   PDF (798KB) ( 303 )   Save BACKGROUND: Currently, there are few kinds of drugs to treat kidney diseases, and many systemic drugs have some problems, such as serious side effects, rapid degradation in the body circulation and so on. At present, active targeting of nanoparticles has become a hot spot in the field of drug delivery, and the exploration of the pathological mechanism related to active targeting of nanoparticles is becoming more and more abundant. OBJECTIVE: To summarize the active targeting strategies in common renal diseases. METHODS: The first author and the second author searched CNKI, Wanfang, VIP, and PubMed databases using “nanoparticles, active targeting, target, kidney, kidney disease” as English key words and “nanoparticles, nanoparticles, targeting, active targeting, kidney disease, kidney” as Chinese key words. All relevant articles published before July 2, 2023 were retrieved, screened, concluded, and summarized. Finally, 62 articles were included for the summary. RESULTS AND CONCLUSION: The active targeting effect of nanoparticles has been studied in many common kidney diseases. The mechanism of active targeting is mainly the binding of ligands and receptors, by modifying the ligand on the nanoparticles to specifically target the receptor on the cells in the kidney; in which way active targeting is realized. Under different renal pathological conditions, the pathological changes of specific kidney sites may become the key breakthrough point to achieve active targeting. Although kidney-targeting nanoparticles have shown promise in the treatment of nonneoplastic kidney diseases, but it is still in the experimental phase in animals, and it is still a long way from applying these results to medical work. Figures and Tables | References | Related Articles | Metrics