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    08 August 2020, Volume 24 Issue 22 Previous Issue    Next Issue
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    Preparation and characterization of sodium methacrylate modified photocrosslinked alginate hydrogel scaffold
    Zhao Delu, Tie Chaorong, Yang Sisi, Sun Zhen, Wang Xin, Zhu Huaian, Yin Miao
    2020, 24 (22):  3445-3451.  doi: 10.3969/j.issn.2095-4344.2276
    Abstract ( 1279 )   PDF (30754KB) ( 151 )   Save

    BACKGROUND: Photocrosslinked alginate hydrogel has been a popular bone tissue engineering material because of its excellent biocompatibility and minimally invasive injection, but there are still problems such as insufficient strength and poor cell adhesion.

    OBJECTIVE: To construct the negatively charged hydrogels by introducing sodium methacrylate into photocrosslinked alginate hydrogels, and to explore the changes in its physical performance and cell adhesion.

    METHODS: After preparation of methacrylated alginate by reacting sodium alginate with 2-aminoethyl methacrylate, methacrylated alginate, photoinitiator and sodium methacrylate (0, 20, 40, 60 mmol/L) were homogeneously mixed. The negatively charged photocrosslinked alginate hydrogels were prepared under ultraviolet light. The functional groups of the hydrogels were analyzed by fourier transform infrared spectroscopy. The surface morphology of the hydrogels was observed by scanning electron microscopy and the swelling ratio was measured. MC3T3-E1 cells were cultured with each group of hydrogels for 48 hours, and the cytotoxicity of the hydrogels was investigated by cell counting kit-8 assay. MC3T3-E1 cells were seeded on the surface of each group of hydrogels. The early adhesion of the cells was observed by live/dead staining at the 4th hour, and cell spreading was observed on the 3rd day.

    RESULTS AND CONCLUSION: (1) Fourier transform infrared spectroscopy demonstrated that the introduction of sodium methacrylate could lead to a new peak at wavenumber of about 1 600 cm-1 in the hydrogel infrared wave, which was from the sodium methacrylate. (2) Scanning electron microscope observed that the density of the negatively charged photocrosslinked alginate hydrogels increased and the pore size of the gels decreased with augment of concentrations of sodium methacrylate. (3) The swelling ratio of the hydrogel decreased with the increase of the concentration of sodium methacrylate. (4) The live/dead staining revealed that the cells grew well on the surface of each hydrogel, and the cell viability reached above 95%. The cell counting kit-8 assay results showed that the negatively charged photocrosslinked alginate hydrogels had no cytotoxicity. (5) The early cell adhesion rate increased gradually and the cell extension became better with the increase of concentration of sodium methacrylate. (6) In summary, the introduction of sodium methacryl into photocrosslinked alginate hydrogels can adjust its physical properties and significantly improve its cell adhesion.

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    Preparation and characterization of calcined bone/chitosan composite material
    Liao Jian, Huang Xiaolin, Zhou Qian, Cheng Yuting, Huo Hua, Li Fang, Wu Chao, Shi Qianhui, Liao Yunmao, Liang Xing
    2020, 24 (22):  3452-3459.  doi: 10.3969/j.issn.2095-4344.2306
    Abstract ( 568 )   PDF (35725KB) ( 58 )   Save

    BACKGROUND: Chitosan exhibits good physiochemical properties and biocompatibility, but it has poor biological activity of osseointegration. Therefore, it needs to combine with other materials for bone repair.

    OBJECTIVE: Calcined bone/chitosan composite was prepared and its physiochemical properties and biocompatibility were analyzed.

    METHODS: Calcined bone/chitosan composite was prepared at a mass ratio of 1∶2, 1∶1, 2∶1 respectively by solution blending method. The physicochemical properties of three composite materials were characterized. Passage 5 mouse L929 fibroblasts were treated with the leaching solution of three composite materials. The cytotoxicity of three composite materials was detected by the CCK-8 test.

    RESULTS AND CONCLUSION: (1) X-ray diffraction and Fourier Transform Infrared Spectroscopy showed that the essential components of three composite materials were hydroxyapatite and β-tricalcium phosphate. The characteristic diffraction peaks of hydroxyapatite/β-tricalcium phosphate increased with the increase of the proportion of calcined bone. (2) Scanning electron microscopy showed that calcined bone particles were evenly dispersed in chitosan medium. (3) With the increase of the proportion of calcined bone, the compressive strength of the composite decreased gradually. (4) After 7 days of culture, the cells in the leaching solution of three composite materials grew well without obvious change in morphology. By the ninth day, the relative proliferation rate of the cells in the leaching solution of three composite materials was over 90%. Cytotoxicity was grade 1, which meets the safety standard of biomaterials. (5) These results suggest that the calcined bone/chitosan composite has good structural characteristics, physicochemical properties and suitable compressive strength and is safe and non-toxic

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    Effects of hydrogel three-dimensional culture on the characteristics of human amniotic mesenchymal stem cells and paracrine effect
    Wang Qi, Yang Xiaoshuang, Wang Dali
    2020, 24 (22):  3460-3466.  doi: 10.3969/j.issn.2095-4344.2299
    Abstract ( 629 )   PDF (31774KB) ( 60 )   Save

    BACKGROUND: Studies have shown that mesenchymal stem cells can reduce inflammation, promote wound healing, and reduce scar formation in wound healing. However, previous two-dimensional culture environment can lead to differences in gene expression, signal transduction, and morphology because of intracellular contact inhibition. 

    OBJECTIVE: To investigate whether the ability of wound healing related factors secreted by human amniotic mesenchymal stem cells is affected by two-dimensional or three-dimensional culture environment.

    METHODS: The human amniotic mesenchymal stem cells cultured by traditional enzyme digestion method were inoculated in traditional cell culture flask (two-dimensional culture group) and ShakeGelTM 3D hydrogel (three-dimensional culture group) and induced to differentiate into adipocytes, osteoblasts, and chondrocytes, respectively. The direction of cell differentiation was determined by immunofluorescence staining. Human amniotic mesenchymal stem cells were fused to 70%-80% in two culture environments, and the growth characteristics and morphology of cells were observed under inverted phase contrast microscope and laser confocal microscope. After 24 hours of culture, relative mRNA expression of wound healing-related factors was detected by reverse transcription-quantitative polymerase chain reaction. After 48 hours of culture, the protein expression of wound healing-related factors was detected by the enzyme-linked immunosorbent assay.

    RESULTS AND CONCLUSION: (1) Human amniotic mesenchymal stem cells cultured in two-dimensional culture group were flat and spindle-shaped, which was a typical mesenchymal stem cell-like morphology. Human amniotic mesenchymal stem cells in the three-dimensional culture group were round and evenly dispersed in each layer of the hydrogel. (2) Human amniotic mesenchymal stem cells in the three-dimensional culture group exhibited the potential to differentiate into adipocytes, osteoblasts, and chondrocytes. (3) The mRNA expression of interleukin-6, interleukin-8, epidermal growth factor, basic fibroblast growth factor, hyaluronic acid, hepatocyte growth factor, and vascular endothelial growth factor in the three-dimensional culture group was significantly higher than that in the two-dimensional culture group (P < 0.001, P < 0.05). There were no significant differences in the mRNA expression of interleukin-4, interleukin-10, tissue inhibitors of metalloproteinases, matrix metalloproteinase, transforming growth factor and keratinocyte growth factor between three-dimensional and two-dimensional culture groups (P > 0.05). (4) The protein expression of interleukin-6, interleukin-8, interleukin-10, epidermal growth factor, basic fibroblast growth factor, hepatocyte growth factor, transforming growth factor β1 and vascular endothelial growth factor in the three-dimensional culture group was significantly higher than that in the two-dimensional culture (P < 0.001, P < 0.01, P < 0.05). There were no significant differences in the protein expression of interleukin-4, tissue inhibitors of metalloproteinases, matrix metalloproteinase, and keratinocyte growth factor between two-dimensional and three-dimensional culture groups (P > 0.05). (5) These findings suggest that human amniotic mesenchymal stem cells cultured in three-dimensional hydrogel show better morphology and more encouraging paracrine effect of wound healing related factors than those cultured in traditional two-dimensional culture environment. 

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    Combination of magnesium ion with mineralized collagen intervenes osteogenic differentiation of mouse preosteoblasts
    Sun Xirao, Sun Baozhai, Zhang Zhenbao
    2020, 24 (22):  3467-3473.  doi: 10.3969/j.issn.2095-4344.2266
    Abstract ( 558 )   PDF (27239KB) ( 269 )   Save

    BACKGROUND: Preliminary study has shown that the composite materials composed of magnesium-based materials and mineralized collagen have a good supporting effect on repairing the critical defects, which can improve the mechanical strength of mineralized collagen and premature collapse during bone healing to some extent. However, magnesium-based metals degrade fast in chloride-containing solutions (including human body fluids or plasma), and the effects of releasing magnesium ions on the proliferation and differentiation of osteoblasts are unknown.

    OBJECTIVVE: To investigate the effects of magnesium ion combined with mineralized collagen on osteogenic differentiation of mouse preosteoblasts in vitro.

    METHODS: Mineralized collagen extracts were prepared from complete medium with magnesium ion concentration of 0, 5, 10, and 20 mmol/L. Mouse preosteoblasts were cultured with four mineralized collagen extracts, respectively, which were divided into mineralized collagen group, and 5, 10 and 20 mmol/L Mg2++mineralized collagen groups. The mouse preosteoblasts cultured in complete medium were used as control group. The cell morphology, proliferation, apoptosis, intracellular microfilament actin, and the activity of alkaline phosphatase and expression level of the osteogenic gene Runx2 after osteogenic differentiation were detected.

    RESULTS AND CONCLUSION: (1) After 24 hours of culture, the cells in the mineralized collagen group, and 5 and 10 mmol/L Mg2++ mineralized collagen groups adhered well, which showed no significant difference from the blank control group, and the elongated spindle cells with many synapses linked to the adjacent cells were observed. The cells in the 20 mmol/L Mg2++mineralized collagen group showed obvious pyknosis. (2) After 1, 3 and 5 days of culture, the cell viability in the 10 mmol/L Mg2++mineralized collagen group was significantly higher than that in the other four groups (P < 0.05). There was no significant difference among mineralized collagen, 5 mmol/L Mg2++ mineralized collagen and blank control groups (P > 0.05). The cell viability in the 20 mmol/L Mg2++mineralized collagen group was significantly lower than that in the mineralized collagen group (P < 0.05). (3) After 3 days of culture, DAPI staining showed that 20 mmol/L Mg2++mineralized collagen group had obvious nuclear disintegration, the other four groups had no obvious nuclear disintegration. (4) After 24 hours of culture, phalloidin staining showed that except the blank control and 20 mmol/L Mg2++mineralized collagen groups, the other three groups showed completely extended cell structure, and clear actin microfilaments, especially the 10 mmol/L Mg2++mineralized collagen group. (5) After 7 days of osteogenic differentiation, except for 20 mmol/L Mg2++mineralized collagen group, the activity of alkaline phosphatase and the expression level of Runx2 gene in the other three groups were significantly higher than those in the blank control group (P < 0.05), and those in the 10 mmol/L Mg2++mineralized collagen group was significantly higher than those in the 5 mmol/L Mg2++mineralized collagen and mineralized collagen groups (P < 0.05). (6) These results suggest that the combination of magnesium ion with mineralized collagen should be applied with appropriate concentration range of magnesium ion (≤ 10 mmol/L).

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    Three-dimensional printed collagen/chitosan scaffold improves neurological recovery after spinal cord injury in rats
    Shi Xinyu, Li Xiaohong, Ye Yichao, Wang Jingjing, Sun Xiaozhe, Zhang Yanlong, Duan Jinghao, Wei Mengguang, Zhang Sai
    2020, 24 (22):  3474-3479.  doi: 10.3969/j.issn.2095-4344.2279
    Abstract ( 742 )   PDF (26309KB) ( 76 )   Save

    BACKGROUND: Three-dimensional (3D) printing technology can be used to prepare bioscaffolds to meet the requirements of shape, size and surface morphology of spinal cord implantation.

    OBJECTIVE: To investigate the effect of 3D printed collagen/chitosan scaffolds on the recovery of neurological function in rats with spinal cord injury.

    METHODS: The collagen/chitosan scaffolds were prepared by freeze-drying method with a mass ratio of 2∶1. The 3D printed collagen/chitosan scaffolds were prepared by 3D printer. The porosity and elastic modulus of the scaffolds were measured, and the morphology of the scaffolds was observed by electron microscope. Neural stem cells were co-cultured with 3D printed collagen/chitosan scaffold, and common collagen/chitosan scaffold, respectively, for scanning electron microscope and cell counting kit-8 assay. Forty female Sprague-Dawley rats (provided by Academy of Military Sciences of PLA) were randomly divided into four groups: sham-operated, spinal cord injury, common collagen/chitosan scaffold, and 3D printed collagen/chitosan scaffold groups. The rats in the latter three groups were used to prepare complete spinal cord transected injury model, followed by filled with the corresponding scaffold materials. Basso, Beattie, Bresnahan scores of the posterior limb, slope test, neuroelectrophysiological detection and MRI were conducted at each time point after surgery. The study was approved by the Animal Ethics Committee of Tianjin Key Laboratory of Traumatic Brain Injury.

    RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that 3D printed collagen/chitosan scaffolds had interconnected porous structure, and the internal structure of common collagen/chitosan scaffolds was disordered. (2) Neural stem cells grew well on the surface of scaffolds and fully extended. The activity of neural stem cells on the surface of 3D printed collagen/chitosan scaffolds was significantly higher than that of the common collagen/chitosan scaffold group (P < 0.05). (3) The porosity and modulus of elasticity in the 3D printed collagen/chitosan scaffold group were higher than those in the common collagen/chitosan scaffold group (P < 0.05). (4) The Basso, Beattie, Bresnahan score in the 3D printed collagen/chitosan scaffold group was higher than that in the spinal cord injury and common collagen/chitosan scaffold groups (P < 0.05) at 3-8 weeks after surgery, and the angle of slope experiment at 4, 6 and 8 weeks after surgery was higher than that in the spinal cord injury and common collagen/chitosan scaffold groups (P < 0.05). (5) The amplitude of motor evoked potential and somatosensory evoked potential in the 3D printed collagen/chitosan scaffold group were higher than those in the spinal cord injury and common collagen/chitosan scaffold groups (P < 0.05), and the latency of motor evoked potential and somatosensory evoked potential were shorter than those in the spinal cord injury and common collagen/chitosan scaffold groups (P < 0.05). (6) MRI plain scan showed that the amplitude of motor evoked potential and somatosensory evoked potential in the 3D printed collagen/chitosan scaffold group were higher than those in the spinal cord injury and common collagen/chitosan scaffold groups (P < 0.05). 3D printed collagen/chitosan scaffold group had good continuity and more nerve fiber bundles passing through the injury site. (7) The results imply that 3D printed collagen/chitosan scaffolds can promote the repair of nerve function in the spinal cord injury rats.

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    In vitro anti-tuberculosis effect of chitosan-gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogel
    Zhang Helong, Wang Huiyan, Li Zhuo, Gao Jianguo, Zhai Qian
    2020, 24 (22):  3480-3485.  doi: 10.3969/j.issn.2095-4344.2280
    Abstract ( 777 )   PDF (27146KB) ( 78 )   Save

    BACKGROUND: Anti-tuberculous chemotherapy is the main method for treating bone and joint tuberculosis. However, systemic administration hardly maintains the effective drug concentration in the focus area, and the therapeutic efficacy is unsatisfactory.

    OBJECTIVE: To prepare a chitosan-gelatin/poly(lactic-co-glycolic acid) combined with drug-loaded hydrogel, which can release anti-tuberculosis drugs in situ for a long time and promote osteogenesis.

    METHODS: Isoniazid, a hydrophilic anti-tuberculosis drug, and a hydrophobic stromal cell derived factor-1 were loaded into poly(lactic-co-glycolic acid) by double emulsion method to prepare drug-loaded poly(lactic acid co-glycolic acid) microspheres, which were then mixed into chitosan gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogel. The ability of drug delivery and anti-tuberculosis of poly(lactic acid co-glycolic acid) microspheres and chitosan gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogels in vitro were tested. MC3T3-E1 cells were inoculated on the surface of microspheres and hydrogel respectively. The biocompatibility was detected by cell counting kit-8 assay. The osteogenetic activity was detected by alkaline phosphatase activity.

    RESULTS AND CONCLUSION: (1) The burst release of isoniazid in the microspheres was about 23.3% in 1 hour, 42.6% in 2 days, and then it entered the sustained-release stage in the later 25 days. The burst release of stromal cell derived factor was about 19.8% in 1 hour, 44.7% in 2 days, and then it entered the sustained-release stage in the next 25 days. The release of isoniazid and stromal cell-derived factor in the combined drug-loaded hydrogel was 8.3% and 8.5% in the first hour, respectively. The cumulative release rates on the second day were 15.2% and 17.6%, respectively, which were much lower than that of poly(lactic acid co-glycolic acid) microspheres. (2) After 4 weeks in vitro, the antibacterial diameter of the combined drug-loaded hydrogel was much larger than that of the drug-loaded microspheres, and the antibacterial rate was higher than that of the drug-loaded microspheres (P < 0.05). (3) The combined drug-loaded hydrogel and the drug-loaded microspheres had good cytocompatibility and cell viability was about 100%. (4) After 5 and 10 days of culture, there was no significant difference in the activity of alkaline phosphatase on the surface of drug-loaded hydrogel and drug-loaded microspheres. (5) These results show that the in situ chitosan-gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogel can be used for treating tuberculosis and other bone and joint infections.       

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    Micro-arc oxidation and osteoblast proliferation and osteogenic differentiation ability on titanium surface
    Wang Yanling, Shao Zhe, He Wei
    2020, 24 (22):  3486-3490.  doi: 10.3969/j.issn.2095-4344.2290
    Abstract ( 451 )   PDF (20186KB) ( 152 )   Save

    BACKGROUND: Electrochemical method based nanoscale hydroxyapatite coating has slow degradation speed (8-12 weeks). Micro-arc oxidation based method could form homogeneous coating on complex surfaces, and this coating promotes cell adhesion and ingrowth in bone tissues.

    OBJECTIVE: To explore the effect of micro-arc oxidation hydroxyapatite coating titanium alloy on osteoblast proliferation and osteogenic differentiation ability.

    METHODS: Hydroxyapatite coating titanium alloy materials were prepared by electrochemical method and micro-arc oxidation method. The contact angles of the two materials were detected. Osteoblasts (hFOB1.19) were incubated on the hydroxyapatite coating titanium alloy materials for 48 hours. The morphological changes of osteoblasts on the materials were observed under scanning electron microscope. The cell proliferation was detected by MTT method at 1, 12, 24, 48 and 72 hours. The cell count and alkaline phosphatase activity were detected at 1, 3 and 5 days of culture. At 5 days, the expression levels of bone morphogenetic proteins 2 and 4 were detected by western blot assay.

    RESULTS AND CONCLUSION: (1) The contact angle in the micro-arc oxidation group was smaller than that in the electrochemical group [(66.5±2.2)°, (52.8±2.1)°, P=0.001 5)]. (2) Scanning electron microscope revealed that the osteoblasts in the electrochemical group had an irregular and shrunken shape, and adhered loosely to the material surface. The osteoblasts in the micro-arc oxidation had a fully outstretched and flat shape, and adhered tightly to the material surface. (3) From 12 to 72 hours, the cell proliferation in the micro-arc oxidation group was faster than that in the electrochemical group (P < 0.05). At 3 and 5 days after culture, the cell proliferation in the micro-arc oxidation group was faster than that in the electrochemical group (P < 0.05). (4) At 1, 3 and 5 days, the alkaline phosphatase activity of osteoblasts in the micro-arc oxidation group was higher than that in the electrochemical group (P < 0.05). (5) The expression levels of bone morphogenetic proteins 2 and 4 were significantly up-regulated in the micro-arc oxidation group compared with the electrochemical group (P < 0.05). (6) These results indicate that micro-arc oxidation hydroxyapatite coated titanium alloy increases osteoblast proliferation and osteogenic differentiation ability.

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    Tensile properties of three-dimensional printed porous titanium alloy trabecular bone
    Zhang Lan, Wang Xiang, Liu Jun, Zhang Chunqiu, Ye Jinduo, Liu Lu
    2020, 24 (22):  3498-3503.  doi: 10.3969/j.issn.2095-4344.2274
    Abstract ( 657 )   PDF (23830KB) ( 51 )   Save

    BACKGROUND: The three-dimensional printed titanium alloy porous structure has been developed rapidly in orthopedic implant design and clinical application due to its good mechanical properties and biocompatibility. Compared with coated prosthesis, the porous structure of titanium alloy trabecular bone has the advantages of fast and good bone growth. In order to ensure the safety of orthopedic implants, the tensile, shear and flexural fatigue strength of trabecular bone structures are determined by experimental methods.

    OBJECTIVE: To investigate the mechanical properties of trabecular bone porous structure by mechanical experiments and finite element numerical simulation.

    METHODS: (1) Tensile test of three-dimensional printed titanium alloy trabecular bone: three-dimensional printed titanium alloy trabecular bone was designed and fabricated. The wire diameter was 0.28-0.35 mm, the pore size was 0.71 mm, and the porosity was 73%. The tensile strength was detected, and the failure mechanism was analyzed. The effect of different printed parts on the tensile strength of trabecular bone was analyzed. (2) Numeric simulation test: a solid model of the tensile specimens including the theoretical structure of the trabecular bone was established to simulate the tensile failure process of trabecular bone specimens.

    RESULTS AND CONCLUSION: (1) The ultimate load of the three-dimensional printed titanium alloy trabecular bone was 39.55-47.11 kN, and an equivalent ultimate tensile stress was 62.79-74.53 MPa. The result of tensile failure was fracture of the network structure, suggesting that titanium alloy trabecular bone had higher tensile strength. (2) Results of tensile test and numeric simulation test showed that the failure location of trabecular bone was mainly on the wire diameter, but not on the interface between trabecular bone and titanium alloy solid. (3) The tensile failure load obtained by numerical simulation was lower than that of experimental results. The main reason is that the wire diameter of the three-dimensional printed trabecular bone (280-350 μm) was larger than that of the theoretical size (142 μm), and the pore size (75% porosity) was smaller than the theoretical value (96% porosity).

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    Biological behaviors of fibroblasts on the surface of TiO2 nanotubes with different diameters after annealing treatment
    Li Hongcai, Ma Zhuang, Guo Youling
    2020, 24 (22):  3504-3509.  doi: 10.3969/j.issn.2095-4344.2295
    Abstract ( 389 )   PDF (29056KB) ( 265 )   Save

    BACKGROUND: Previous studies have shown that titanium nanotubes with different diameters affect the adhesion and growth of cells on the implant surface.

    OBJECTIVE: To investigate the effects of annealing treatment on the biological behaviors of fibroblasts on the surface of TiO2 nanotubes with different diameters.

    METHODS: TiO2 nanotubes were prepared by polishing pure titanium samples through anodizing at 5 V and 20 V respectively, and then annealed. The pure titanium samples were divided into six groups: P (polishing titanium), NT5 (TiO2 nanotubes prepared at 5 V), NT20 (TiO2 nanotubes prepared at 20 V), A-P (annealing treatment and polishing titanium), A-NT5 (TiO2 nanotubes prepared at 5V and annealed) and A-NT20 (TiO2 nanotubes formed at 20 V and annealed). Field emission scanning electron microscopy was used to obsesrve the surface topography. Fibroblasts were inoculated on the surface of each group of samples. After 60 and 120 minutes of culture, the number of cells adhering to titanium sample surface was counted using cell nucleus staining method. On day 1 of culture, cell morphology was observed using scanning electron microscopy. On days 1, 3 and 5 of culture, cell proliferation was detected by MTT method. On day 3 of culture, the secretion of collagen fiber was detected by picro-sirius red staining method.

    RESULTS AND CONCLUSION: (1) The annealing treatment had no significant effect on the morphology and diameter of the nanotubes. (2) The number of adherent cells in the NT5 and NT20 groups was significantly lower than that in the P group. The annealing treatment increased the number of fibroblasts on the surface of polished pure titanium and decreased the number of fibroblasts in the NT5 and NT20 groups. (3) Annealing enhanced the viability of fibroblasts on the surface of polished pure titanium and decreased the viability of cells on the surface of nanotubes prepared at 5 and 20 V. (4) Cell viability in the NT5 and NT20 groups was lower than that in the P group. Annealing treatment increased the viability of cells on the surface of polished pure titanium and decreased the viability of cells on the surface of nanotubes prepared at 5 and 20 V. (5) The level of collagen on the surface of nanotubes in the NT5 and NT20 groups was higher than that in the P group. Annealing treatment increased the level of collagen on the surface of polished pure titanium and decreased the level of collagen in the NT5 and NT20 groups. These findings suggest that TiO2 nanotubes inhibit the adhesion, spreading and proliferation of fibroblasts to different degrees; annealing treatment can enhance this inhibitory effect; TiO2 nanotubes enhance collagen secretion by fibroblasts to different degrees, and annealing treatment inhibits the enhancement.

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    A comparative study on the effect of nano-pearl powder ground with different dispersion media
    Mao Qiuhua, Xu Pu, Cheng Yanan, Liao Jun, Chen Ling, Li Muyuan
    2020, 24 (22):  3510-3514.  doi: 10.3969/j.issn.2095-4344.2301
    Abstract ( 475 )   PDF (24503KB) ( 172 )   Save

    BACKGROUND: To retain more biological activity of organic matter and materials, it is necessary to grind and refine the pearl powder by physical method. The ball grinding method can retain the organic matter in the pearl powder and its activity to the greatest extent. The nanomaterials prepared by ball milling in different dispersion media exhibit different effects.

    OBJECTIVE: To compare nano-pearl powder milled with distilled water and anhydrous ethanol. 

    METHODS: Nano-pearl powder was prepared by grinding with anhydrous ethanol and water as dispersion medium respectively. The prepared nano-pearl powder was compared by scanning electron microscope, transmission electron microscope, X-ray diffraction, Kjeldahl method and by determining amino acid content in foods.

    RESULTS AND CONCLUSION: (1) The nano-pearl powder prepared with anhydrous ethanol as dispersion medium was mainly round particles of different sizes (range, 30-50 nm), with the average grain size of 20 nm. The relative percentage of calcite calcium carbonate increased to 7%. The contents of protein and amino acid did not change obviously. (2) The nano-pearl powder prepared with distilled water as dispersion medium was mainly round particles of different sizes with the average grain size of 30 nm. There were irregular grain-like or block-like particles. The relative percentage of calcite calcium carbonate increased to 10%. The contents of protein and amino acid decreased. (3) These results showed that there was a significant difference in the particle size of the pearl powder ground with distilled water and anhydrous ethanol. The pearl powder prepared with anhydrous ethanol as the dispersion medium had a finer more uniform particle size.

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    Stress relaxation and creep test of modified glass ionomer cement
    Ding Jie, Li Xinying, Li Peng
    2020, 24 (22):  3515-3520.  doi: 10.3969/j.issn.2095-4344.2263
    Abstract ( 489 )   PDF (28353KB) ( 65 )   Save

    BACKGROUND: Most of studies on the mechanical properties of modified glass ionomer cement mainly focus on the compression and bending experiments, but there are few reports on the stress relaxation and creep experiments of glass ionomer cement after adding strontium hydroxyapatite.

    OBJECTIVE: To compare the stress relaxation and creep characteristics of traditional glass ionomer cement, composite resin enamel adhesive and modified glass ionomer cement.

    METHODS: Strontium doped hydroxyapatite was added into glass ionomer cement according to the mass ratio of 15%, and then the modified glass ionomer cement was prepared. Samples of modified glass ionomer cement, composite resin enamel adhesive and traditional glass ionomer cement were maded. Ten samples from each group were taken for stress relaxation test and another 10 samples for creep test.

    RESULTS AND CONCLUSION: (1) At 7 200 s in the stress relaxation test, the stress in the traditional group was decreased by 1.18 MPa, decreased by 1.39 MPa in the composite group, and decreased by 1.38 MPa in the modified group. The decreased value in the traditional group was significantly less than that in the composite and modified groups (P < 0.05). There was no significant difference between composite and modified groups (P > 0.05). (2) At 7 200 s in the creep test, the stress in the traditional group was increased by 0.24%, increased by 0.33% in the composite group, and increased by 0.32% in the modified group. The increased value in the traditional group was significantly less than that in the composite and modified groups (P < 0.05). There was no significant difference between composite and modified groups (P > 0.05). (3) The viscoelastic properties of glass ionomer cement are improved by compounding 15% strontium-doped hydroxyapatite with glass ionomer cement. The increase of viscoelasticity is beneficial to the adhesion and bulk bond strength of glass ionomer cement.

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    Application of three-dimensional printed digital surgical guide in the anterior maxillary dental implant
    Zhang Bin, Li Jun, Zhang Junhua, Sun Lihua, Liu Yusan, Cui Caiyun
    2020, 24 (22):  3521-3526.  doi: 10.3969/j.issn.2095-4344.2278
    Abstract ( 482 )   PDF (30280KB) ( 195 )   Save

    BACKGROUND: Conventional implantation at anterior aesthetic region is difficult to achieve ideal three-dimensional position, and needs high implantation accuracy.

    OBJECTIVE: To evaluate the clinical application effect of three-dimensional printed digital guide technology in anterior dental implant.

    METHODS: Eighty-six cases of dental implants were divided into two groups. Control group (n=43, 52 implants) received conventional dental implantation. Trial group (n=43, 52 implants) received implantation under three-dimensional printed digital guides. The accuracy of the three-dimensional position of the implants was measured. The modified plaque index, modified bleeding index, probing depth and the satisfaction of patients with implant denture were measured at 6 months after implantation.

    RESULTS AND CONCLUSION: (1) The errors of vertical and horizontal directions at the top and the root after implantation in the trial group were significantly fewer than those in the control group (P < 0.05). (2) The modified plaque index, modified bleeding index, and probing depth in the trial group were significantly lower than those in the control group (P < 0.05). (3) The satisfaction of patients in the trial group was 98% (42/43), which was higher than 86% (37/43) in the control group. (4) In summary, three-dimensional printed digital guide plate used in dental implant dentures can improve the three-dimensional position accuracy after implantation and improve the postoperative clinical effect.

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    Changes in three physical indicators of the muscle after far-infrared ceramic microsphere intervention
    He Jianwei, Zheng Hanshan, Xu Jian, Zhang Ying
    2020, 24 (22):  3527-3533.  doi: 10.3969/j.issn.2095-4344.2287
    Abstract ( 430 )   PDF (745KB) ( 120 )   Save

    BACKGROUND: Far-infrared wave therapy can accelerate blood flow rapidly, strengthen the exchange of substance and energy among tissues, and promote the rapid recovery of musculoskeletal micro-injury. The far-infrared ceramic microsphere is a new functional rehabilitation material in the field of physical therapy and rehabilitation in recent years.

    OBJECTIVE: To verify the therapeutic effectiveness of far-infrared ceramic microsphere intervention on muscle extensibility, stiffness, and elasticity after musculoskeletal injury.

    METHODS: Male students aged 18-21 years who were diagnosed with posterior femoral muscle injury in each sports specialty were selected as test subjects. Twenty subjects were selected and randomly divided into two groups (n=10/group), and then underwent far-infrared therapeutic apparatus (control group) and far-infrared ceramic microsphere intervention treatment (trial group) for 2 consecutive weeks. A non-invasive muscle detection system was used to collect muscle extensibility, muscle stiffness, and muscle elasticity data before and 3, 7, and 14 days after treatment.

    RESULTS AND CONCLUSION: (1) The muscle extensibility in the trial group at 3, 7, and 14 days after treatment was higher than that before treatment (P < 0.05, P < 0.01), and it had returned to the level of the healthy side at 14 days after treatment (P > 0.05). In the control group, the muscle extensibility at 14 days after treatment was higher than that before treatment (P < 0.05), but it was still lower than that of the healthy side (P < 0.05). The muscle extensibility at different time points in the trial group was higher than that in the control group (P < 0.05, P < 0.01). (2) The muscle stiffness in the trial group at 3, 7, and 14 days after treatment was higher than that before treatment (P < 0.05, P < 0.01), and at 14 days after treatment, it had returned to the level of the healthy side (P > 0.05). In the control group, the muscle stiffness at 14 days after treatment was higher than that before treatment (P < 0.05), but it was still lower than that of the healthy side (P < 0.05). The muscle stiffness at different time points in the trial group was higher than that in the control group (P < 0.05, P < 0.01). (3) The muscle elasticity in the trial group at 3, 7, and 14 days after treatment was higher than that before treatment (P < 0.05, P < 0.01), and at 14 days after treatment it had returned to the level of the healthy side (P > 0.05). In the control group, the muscle elasticity at 14 days after treatment was higher than that before treatment (P < 0.05), but it was still lower than that of the healthy side (P < 0.05). The muscle elasticity at different time points in the trial group was higher than that in the control group (P < 0.05, P < 0.01). (4) In summary, far-infrared ceramic microspheres can improve muscle extensibility and elasticity, reduce muscle stiffness and promote the recovery of muscle damage.

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    In vitro antibacterial activity and biocompatibility of a porous scaffold containing magnesium
    Ma Rui, Wang Jialin, Li Yongwei, Wang Wei
    2020, 24 (22):  3534-3539.  doi: 10.3969/j.issn.2095-4344.2272
    Abstract ( 412 )   PDF (26054KB) ( 57 )   Save

    BACKGROUND: The three-dimensional organic/inorganic scaffold materials using polymer/bioceramic composites can endow the necessary physical and chemical properties and enhance the mechanical properties of the materials. However, most bone substitution materials cannot prevent infection at the defect site. It has been found that the degradation of magnesium can produce local alkaline environment, so that magnesium has certain antibacterial activity.

    OBJECTIVE: To investigate the in vitro antibacterial activity and cytocompatibility of magnesium-containing scaffolds.

    METHODS: Polylactic acid/β-tricalcium phosphate/magnesium porous scaffolds were prepared by low-temperature rapid prototyping technology. The PTM (2∶1) and PTM (1∶2) groups referred to two mixing mass ratios (β-tricalcium phosphate∶magnesium = 2∶1 and 1∶2), respectively. Two scaffolds of polylactic acid (P group) and polylactic acid/β-tricalcium phosphate (PT group) were also prepared by low-temperature rapid prototyping technology. The surface morphology, pore size, porosity and compression modulus of the scaffolds were measured. Staphylococcus aureus (ATCC 35923) was seeded on the scaffolds of each group for 24 hours. The antibacterial activity of the scaffolds was observed through spread plate method and confocal laser scanning microscopy. Mouse preosteoblasts MC3T3-E1 were co-cultured with the scaffolds of each group. The cell attachment and proliferation were evaluated by cell counting kit-8 assay.

    RESULTS AND CONCLUSION: (1) A relatively uniform porous structure was found on the scaffold surfaces in each group. There were no significant differences in the pore size and porosity among groups (P > 0.05). (2) The compression modulus in the PTM (2∶1) and PTM (1∶2) groups were significantly higher than those in the P and PT groups (P < 0.05), and those in the PTM (1∶2) group were significantly higher than those in the PTM (2∶1) group (P < 0.05). (3) The results of the spread plate method showed that the bacterial colony formation unit in the PTM (2∶1) and PTM (1∶2) groups was significantly lower than that in the P and the PT groups (P < 0.05), and the difference among the other groups was insignificant (P > 0.05). (4) After 6 hours of culture, the number of attached cells in the PT, PTM (2∶1) and PTM (1∶2) groups was greater than that in the P group (P < 0.05), and there was no significant difference between PTM (2∶1) and PTM (1∶2) groups (P > 0.05). (5) At 1 day of culture, the cell proliferation in the PT group was superior to that in the P group (P < 0.05). At 4 and 7 days, the cell proliferation in the PT, PTM (2∶1) and PTM (1∶2) groups was superior to that in the P group (P < 0.05), and there was no significant difference between PTM (2∶1) and PTM (1∶2) groups (P > 0.05). (6) These results indicate that the polylactic acid/β-tricalcium phosphate/magnesium scaffold not only possesses good antibacterial activity, but also exhibits excellent cytocompatibility and certain anti-compressive ability.

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    Efficacy of cutting balloon versus semi-compliant balloon for predilation of coronary bifurcation lesions
    Jin Hui, Qiu Cuiting, Sun Yachao, Zeng Hui, Zheng Haijun, Liu Jing, Han Fengjie
    2020, 24 (22):  3540-3546.  doi: 10.3969/j.issn.2095-4344.2283
    Abstract ( 858 )   PDF (735KB) ( 133 )   Save

    BACKGROUND: There is no efficient and unified optimal scheme for treating coronary bifurcation diseases. Simple strategies such as drug-eluting stent implantation in the main branch and drug-coated balloon dilation in the sub-branches are mostly adopted. However, direct drug-coated balloon dilation cannot overcome the problem of elastic retraction of vascular wall, and there is still a risk of branch loss in the long term.

    OBJECTIVE: To investigate the efficacy and safety of a cutting balloon versus a semi-compliant balloon for predilation of coronary bifurcation lesions.

    METHODS: From August 2016 to May 2018, 110 patients with coronary bifurcation lesions admitted at Jiaozuo People’s Hospital were selected, including 83 males and 27 females, aged 18-88 years. The patients were randomized into observation and control groups (n=55/group) and received percutaneous coronary intervention. The main branch in the observation group was predilated by a cutting balloon prior to drug-eluting stent implantation, and the sub-branches were predilated by a cutting balloon prior to drug-coated balloon dilation. The main branch in the control group was predilated by a semi-compliant balloon prior to drug-eluting stent implantation, and the sub-branches were predilated by a semi-compliant balloon prior to drug-coated balloon dilation. Immediate postoperative angiography was performed to determine the forward blood flow TIMI grading of main branches and sub-branches and whether vascular dissection occurred. Coronary angiography quantitative analysis was used to detect the reference diameter, minimum inner diameter and stenosis degree of main and sub-branches before, immediately, 6 and 12 months after surgery. Major cardiovascular adverse events within 12 months after surgery were recorded in both groups. The study was approved by the Ethics Committee of Jiaozuo People’s Hospital.

    RESULTS AND CONCLUSION: (1) Immediate postoperative angiography showed that the TIMI level 3 rate of the main branches and sub-branches in the observation group was higher than that in the control group (P=0.007, 0.015), the incidence of vascular dissection was lower than that in the control group (P=0.023, 0.012), and the emergency target vessel reconstruction rate was lower than that in the control group (P=0.006, 0.026). (2) The success rate of coronary artery maintenance immediately and at 6 and 12 months after surgery in the observation group was higher than that in the control group (all P < 0.001). (3) The minimum inner diameter of main branches and sub-branches in the observation group was larger than that in the control group immediately and at 6 and 12 months after surgery (all P < 0.01). The degree of inner diameter stenosis was smaller than that in the control group (all P < 0.01). (4) The target vessel restenosis rate of main branch and sub-branches in the observation group was lower than that in the control group within 12 months after surgery (P=0.038, 0.043). The incidence of major cardiovascular adverse events was lower than that in the control group (P=0.025). (5) These results indicate that in coronary bifurcation lesions, drug-eluting stent implantation is suitable for main branch lesions and drug coated balloon is suitable for sub-branch lesion. Cutting balloon predilation is safer and more effective than semi-compliant balloon predilation. Cutting balloon predilation can also reduce the rate of target restenosis and the incidence of major cardiovascular adverse events.

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    Bioactivity of the peptide P17-bone morphogenetic protein-2/nano-hydroxyapatite-mineralized collagen composite
    Zhang Xue, Zhang Yang, Cui Fuzhai
    2020, 24 (22):  3547-3552.  doi: 10.3969/j.issn.2095-4344.2300
    Abstract ( 493 )   PDF (25459KB) ( 144 )   Save

    BACKGROUND: A mineralized collagen composite, i.e. nano-hydroxyapatite/collagen (nHAC) has biomimetic three-dimensional structure and good bioactive properties. As a bone tissue engineering material, it is widely used in bone defect repair. A newly designed P17-bone morphogenetic protein-2 (P17-BMP2) has good biocompatibility and osteogenic capacity. Therefore, the composite scaffold material was prepared by combining the new P17-BMP-2 and nHAC, which might be used for the enhancement of osteogenic capacity in the treatment of bone defects.

    OBJECTIVE: To investigate the bioactivity of the P17-BMP-2/nHAC composite.

    METHODS: Rabbit bone marrow mesenchymal stem cells were seed on the P17-BMP-2/nHAC composite and nHAC. After 3 and 7 days of culture, the relative expression level of alkaline phosphatase was detected by RT-PCR. The subcutaneous implantation of P17-BMP-2/nHAC (experimental group) and nHAC (control group) into Sprague-Dawley rats was performed. Masson staining was performed for histological analysis at 12 and 35 days of implantation. P17-BMP-2/nHAC (experimental group) and nHAC (control group) were implanted into the white rabbit mandibular box-shaped bone defect, respectively. At 5 and 15 weeks, gross observation and X-ray were performed. The study was approved by the Medical Ethics Committee of China Medical University School & Hospital of Stomatology.

    RESULTS AND CONCLUSION: (1) The relative expression level of alkaline phosphatase in the P17-BMP-2/nHAC group was significantly higher than that in the nHAC group (P < 0.05). (2) The result of subcutaneous implantation showed that the acute inflammatory response initiated by the P17-BMP-2/nHAC or nHAC was not found. More activated fibroblasts growing into the implants could be found on the sections of P17-BMP-2/nHAC compared to that of nHAC at 35 days after implantation. (3) In the bone defect repair test, gross observation showed that both materials held good defect repair ability, the defect area began to reduce at 5 weeks after implantation, and the defect surface became flat at 15 weeks after implantation. X-ray examination showed that compared with the control group, the defect area was more significantly reduced in the experimental group. (4) These results indicate that P17-BMP-2/nHAC composite scaffold has higher bioactivity and a stronger ability to repair bone defect.

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    Optimization of the coaxial cell printing performance of bioink and printing of tissue-engineered scaffolds with vascular-like structure
    Zhang Yifan, Zhang Jiaying, Xu Mingen, Wang Ling, Zhang He
    2020, 24 (22):  3553-3558.  doi: 10.3969/j.issn.2095-4344.2281
    Abstract ( 510 )   PDF (870KB) ( 415 )   Save

    BACKGROUND: Cells cannot survive in the area 200 μm away from nutrients in vitro. Vascular network construction is crucial for thick tissue and organ regeneration in tissue engineering. Coaxial cell printing provides a new way to construct vascular-like channels in vitro.

    OBJECTIVE: To optimize the coaxial cell printing performance of bioink and to build the tissue-engineered scaffolds with vascular-like structure.

    METHODS: The aseptic sodium alginate solution was prepared by intermittent pasteurization and then frozen. Freeze-dried powder of aseptic silk fibroin was prepared from degummed silk and sealed. The thawed sodium alginate solution was added to the silk fibroin protein freeze-dried powder and human umbilical vein endothelial cells were added to prepare the bioink. The outer axis of the biological three-dimensional printer was connected with the bioink, and the inner axis was connected with the crosslinking agent. The scaffolds were prepared by coaxial printing, and performed by optical coherence tomography, scanning electron microscopy observation and tensile test. Coaxial scaffolds were made by freeze-preserved sodium alginate solution for 7 days with human umbilical vein endothelial cells. Coaxial scaffolds were also made by freeze-dried sodium alginate solution for 7 days with human umbilical vein endothelial cells and silk fibroin protein sealed for 6 months. The cell survival rate was detected by dead and alive staining after 24 hours of culture in vitro. Vascular-like scaffolds with series and parallel structures were designed and printed. The cell proliferation was detected after 1, 3, 7, 10, and 14 days of culture.

    RESULTS AND CONCLUSIONS: (1) The optical coherence tomography showed that the maximum printing height of the bioink was 9 layers and the overall thickness was about 4.4 mm. Scanning electron microscopy showed that the outer wall of hollow fiber-filament of vascular-like scaffolds presented irregular strip-shaped crimp with micron-scale internal connected pore structure, while the inner wall of hollow fiber-filament had denser pore structure. (2) The elastic modulus of silk protein freeze-dried scaffold was higher than that of sodium alginate solution (P < 0.05). (3) The cell survival rate of scaffolds treated with sodium alginate solution for 7 days was (86.7±3.4)%, and that of scaffolds treated with silk protein freeze-dried powder for 7 days was (98.1±1.2)%, indicating that the sodium alginate solution freeze- preserved for 7 days was free of bacteria and the shelf-life of silk protein could be up to 6 months. (4) The proliferation activity of cells cultured with parallel structure for 7, 10, and 14 days was higher than that with series structure (P < 0.05). (5) These results imply that the scaffolds have good biocompatibility and mechanical properties.

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    Polyisobutylene and its thermoplastic elastomers: how to transform from industry to medical treatment
    Jiang Li, Fang Xiaojuan, Pan Banglun, Lin Hanchao, Li Wei
    2020, 24 (22):  3559-3565.  doi: 10.3969/j.issn.2095-4344.2258
    Abstract ( 683 )   PDF (926KB) ( 1119 )   Save

    BACKGROUND: Polyisobutylene and block copolymer and its crosslinked product are a kind of novel thermoplastic elastomer. They have unique properties and excellent biocompatibility, which is a promising medical biomaterial and applied extensively.

    OBJECTIVE: To review the research progress and applications of polyisobutylene and its thermoplastic elastomers, and to discuss the application prospect of polyisobutylene-based polymers as medical implant materials.

    METHODS: A computer-based retrieval of PubMed, Web of Science, CNKI and WanFang databases was conducted for the articles about polyisobutylene published from 1958 to 2019. The key words were “polyisobutylene and block copolymer, polyisobutylene and thermoplastic elastomer, polyisobutylene and biomaterials, polyisobutylene and modification, polyisobutylene and medical application” in English and Chinese, respectively. In accordance with the inclusion and exclusion criteria, 65 eligible articles were included for review.

    RESULTS AND CONCLUSION: Polyisobutylene and block copolymer and its crosslinked products have favorable biocompatibility and stability. By making full use of polyisobutylene-based materials’ advantages, with the combination of other biomaterials and usage of new technology for surface modification, the copolymer will be more competitive in the field of medical implant in the future, including eye implant materials, soft biomaterials and drug delivery systems.

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    Research progress of intervertebral disc repair with decellularized matrix materials
    Jin Xiaoyu, Deng Rongrong, Rong Weihao, Xie Lin, Kang Ran
    2020, 24 (22):  3566-3572.  doi: 10.3969/j.issn.2095-4344.2273
    Abstract ( 581 )   PDF (835KB) ( 266 )   Save

    BACKGROUND: With the development of tissue engineering, the repair and regeneration of disc becomes possible. Decellularized extracellular matrix is an important means for disc regeneration.

    OBJECTIVE: To review and summarize the processing, quality control and application of decellularized matrix materials applied in intervertebral disc regeneration in recent years and put forward the prospect.

    METHODS: PubMed, Web of Science and CNKI databases were searched for the articles concerning decellularized methods and decellularized matrix repairing intervertebral disc with the search terms of “intervertebral disc, decellularization, extracellular matrix, scaffold material, tissue engineering” in English and Chinese, respectively. After screening based on the inclusion and exclusion criteria, the articles with high relevance were included for review.

    RESULTS AND CONCLUSION: The decellularized tissue-engineered intervertebral disc aims to maintain the physiologically relevant bioactivators to a great extent, improve mechanical properties and biocompatibility, and reduce immunogenicity. The decellularized matrix material can simulate the microenvironment of the extracellular matrix in the intervertebral disc. As a cell carrier, it can well induce the differentiation of seed cells, which has achieved certain progress in the repair of intervertebral discs. However, further studies need to address the following issues: proper porosity of decellularized matrix materials, immunological rejection, implant ways in vivo and repair effect.

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    Surface modification of bone tissue engineering implants
    Fang Xu, Dong Junfeng
    2020, 24 (22):  3573-3578.  doi: 10.3969/j.issn.2095-4344.2294
    Abstract ( 595 )   PDF (676KB) ( 118 )   Save

    BACKGROUND: Biomedical implants have been widely used in various orthopedic treatments. However, the existing bone implants often have the disadvantages of poor mechanical properties, immune response, microbial infection, poor healing and so on. Different surface modification techniques can effectively make up for these shortcomings.

    OBJECTIVE: To summarize the surface modification techniques of the current bone tissue engineering implants.

    METHODS: The first author searched the PubMed, CNKI, and VIP databases to retrieve the articles regarding repair of tuberculous bone defect published during 2000-2009 with the search terms “bone tissue engineering; bone implant; surface modification; coating” in Chinese and English, respectively. The articles published recently or in high-impact journals were included in this study.

    RESULTS AND CONCLUSION: The surface of bone tissue engineering implants was modified by inorganic and organic components or by changing the surface topography of the implants. This improves the osteogenesis, bone conductivity, bacteriostasis, and biocompatibility of bone implant to different degrees. However, we need to solve some problems before this new implant is applied to the clinic: how to determine the optimal concentration of different surface modification components, maximize bone healing, inhibit bacterial activity, and avoid other adverse reactions; how to avoid foreign body reaction and immune response caused by particles generated by surface abrasion of these bone tissue engineering implants over time; how to incorporate various growth factors, proteins and other biological molecules into the coating without damaging their respective chemical structures and functions; how to guide the release of growth factors and molecules in a coordinated and controllable way.

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    Small-caliber tissue-engineered vascular stent: how to produce a material with physiological remodeling activity
    Yang Lei, Li Xiafei, Dong Yuzhen, Ma Xianfen, Zhang Qiqing, Zhao Liang
    2020, 24 (22):  3579-3586.  doi: 10.3969/j.issn.2095-4344.2265
    Abstract ( 464 )   PDF (46561KB) ( 49 )   Save

    BACKGROUND: The common clinical treatment methods of cardiovascular disease are vascular reconstruction, including stent interventional therapy, coronary artery bypass grafting and angioplasty.

    OBJECTIVE: To summarize the latest research progress of tissue-engineered vascular stent materials, such as natural derivative stent materials, synthetic macromolecule materials and composite materials, so as to lay a theoretical foundation for small-caliber vascular transplantation.

    METHODS: PubMed, WanFang, and CNI databases were retrieved for the articles published from January 2008 to July 2019. The key words were “tissue engineering, biological material, scaffold material, blood vessel” in Chinese and English, respectively. The documents with old content and repeated conclusions were excluded, and 52 eligible articles were enrolled.  

    RESULTS AND CONCLUSION: Autologous vascular grafts, such as saphenous vein and internal thoracic artery, are the best alternatives to small-caliber vessels. However, restenosis of vascular lumen may be induced after transplantation, and the incidence of thrombosis, infection and transplantation failure increases, which seriously hinders the clinical application. Considering these limitations, researchers have embedded tissue-engineered vascular grafts into cells to produce a living material with physiological remodeling activity. This potential solution may bring hope for the future of vascular grafts.

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    Synthesis of poly(glycerol sebacate) and its research hotspots
    Zhou Jianpeng, Liu Jun, Zheng Zhangluwei, Bao Guangjie, Kang Hong
    2020, 24 (22):  3587-3593.  doi: 10.3969/j.issn.2095-4344.2257
    Abstract ( 660 )   PDF (50314KB) ( 231 )   Save

    BACKGROUND: Poly(glycerol sebacate) holds excellent and good biocompatibility, flexibility and degradability, which is widely used in soft tissue replacement and tissue engineering, drug delivery carrier, wound dressing, and bone-cartilage regeneration.

    OBJECTIVE: To summarize the research progress in the optimal synthesis and medical application of poly(glycerol sebacate) and its composites.

    METHODS: PubMed, Elsevier, CNKI and WanFang databases were retrieved. The key words were “poly(glycerol sebacate), synthesis, cardiac muscle, blood vessels, nerves, skin, drug delivery carrier, wound dressing, bone regeneration" in English and Chinese, respectively. Finally, 43 articles eligible for the inclusion criteria were obtained.

    RESULTS AND CONCLUSION: In recent years, poly(glycerol sebacate) has attracted much attention because of its many excellent properties. Many basic scientific studies and animal experiments have confirmed that it is suitable for tissue engineering. Conventional poly(glycerol sebacate) curing process requires high temperature, high vacuum and long duration, which prevents the polymer from binding directly to cells or temperature-sensitive molecules, resulting in some limitations in its application. The composite scaffold material synthesized with a variety of other materials can make up for the corresponding shortcomings of its application in myocardial and vascular tissue engineering, drug delivery carrier, nerve guiding materials, skin and wound dressing, and bone-cartilage tissue engineering. At present, most of the studies on poly(glycerol sebacate) composites focus on the cytobiology level, and few studies focus on the mechanism of action in vivo. Further study may develop an important material for tissue replacement.

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    Application of a digital articulator based on virtual reality technique in oral repair
    Huang Yating, Zuo Enjun
    2020, 24 (22):  3594-3601.  doi: 10.3969/j.issn.2095-4344.2277
    Abstract ( 775 )   PDF (53283KB) ( 346 )   Save

    BACKGROUND: The development of digital technology has changed the diagnosis and treatment process in traditional oral clinic. The digital workflow can improve patient’s comfort, and save time. Virtual articulator as the new development section has been used in most of the dental design software, which is to replicate the function of mechanical articulator and simulate static and dynamic occlusion. It makes treatment more convenient, accuract and efficient.

    OBJECTIVE: To review the recent progress in the field of operation and clinical application of multiple virtual articulators at home and abroad.

    METHODS: The first author searched the related literature, clinical cases and books by computer in domestic and foreign databases, and the related contents and opinions were summarized.

    RESULTS AND CONCLUSION: (1) Although it has been studied for about 20 years, virtual articulator has not been widely applied because of technical sensitivity and high cost. (2) The transfer of articulator needs to scan the mandible model and record the mandibular movement relation. To define mandibular movement relation, average mandible parameters can be used, the ultrasonic sensor, photoelectric sensor, digital face bow or cone beam computed tomography for individualized records can also be used. (3) At present, virtual articulator has been used in fields of orthognathic surgery, temporomandibular joint disease, implant, and aesthetic repair. Comparative studies have shown that accuracy can meet clinical requirements and save time. However, differences between occlusal systems need to be detected. (4) Virtual articulator can save clinical operation time, improve accuracy, make up for the limitations of mechanical articulator, and has a wide range of application prospects.

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    Effect of soft silicone silver ion dressing applied in burn wounds
    Zhong Shuxian, Shi Yuqing, Yang Yalan, Li Chun
    2020, 24 (22):  3602-3608.  doi: 10.3969/j.issn.2095-4344.2271
    Abstract ( 842 )   PDF (27435KB) ( 253 )   Save

    BACKGROUND: Soft silicone silver ion dressing, a kind of high molecular weight organic compound prepared with Safetac technology, has the characteristics of anti-infection, good permeability and good air permeability. It can provide a good moist environment for wound healing.

    OBJECTIVE: To evaluate the effectiveness of soft silicone silver ion dressings in repairing deep II degree and milder burn wounds.

    METHODS: A computer-based retrieval of CNKI, VIP, WanFang, CBM, PubMed, Embase and Web of Science databases was performed. The randomized controlled trials concerning soft silicone silver ion dressing for repairing deep II degree and milder burn wounds were selected. The treatment group was treated with a single soft silicone silver ion dressing, or a soft silicone silver ion dressing combined with conventional treatment, or combined with other treatments. The control group was treated with conventional treatment, or other treatments, or placebo. After screening, data extraction and quality evaluation, meta-analysis was performed using Review Manager 5.3 software.

    RESULTS AND CONCLUSION: (1) Eleven articles were included, involving 784 patients, 381 patients in the treatment group and 403 patients in the control group. (2) The results of meta-analysis showed that the burn wound healing rate in the treatment group was higher than that in the control group [OR=11.56, 95%CI (9.60, 13.53), P < 0.000 01; OR=13.29, 95%CI (7.54, 19.04), P < 0.000 01; OR=4.10, 95%CI (2.28, 5.93),  P < 0.000 1; OR=1.17, 95%CI (0.42, 1.93), P=0.002] at 7, 14 and 21 days, and the last measurement. The healing time of burn wounds in the treatment group was shorter than that in the control group [OR=-2.81, 95%CI (-3.49, -2.12), P < 0.000 01]. The degree of pain in burn wounds in the treatment group was lower than that in the control group [OR=-0.38, 95%CI (-0.53，-0.24), P < 0.000 01]. There was no significant difference in the positive rate of bacterial culture on wound surface [OR=1.16, 95%CI (0.47, 2.85), P=0.74], burn wound infection [OR=1.44, 95%CI (0.47, 4.41), P=0.52], dressing frequency [OR=-8.04, 95%CI (-18.82, 2.74), P=0.14], wound treatment cost [OR=-98.26, 95%CI (-272.91, 76.40), P=0.27] and adverse reaction [OR=0.61, 95%CI (0.31, 1.20), P=0.15] between treatment and control groups. (3) These results show that the application of soft silicone silver ion dressing on deep II degree and milder burn wounds can improve wound healing rate, shorten wound healing time and alleviate pain.

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