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    28 February 2018, Volume 22 Issue 6 Previous Issue    Next Issue
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    Physicochemical properties of hydroxyapatite/dicalcium phosphate dehydrate bone cement
    Peng Lei, Ding Xiu-ming, Chen Ke-wei, Liu Jian-li, Gu Yun-tao, Bian Yang-yang, Meng Zhu-long, Yao Jiang-ling,
    2018, 22 (6):  821-826.  doi: 10.3969/j.issn.2095-4344.0053
    Abstract ( 493 )   PDF (949KB) ( 638 )   Save
    BACKGROUND: β-tricalcium phosphate (β-TCP) and monocalciumphosphate monohydrate (MCPM) are traditionally considered as reactants for dicalcium phosphate dehydrate (DCPD) bone cement, but little is reported on the hydroxyapatite (HA) as a reactant.
    OBJECTIVE: To verify whether HA and MCPM can be used to prepare DCPD bone cement and to explore the physicochemical properties.
    METHODS: The HA and β-TCP were prepared by wet chemical precipitation method, and mixed with appropriate proportion of MCPM. Then, the HA-DCPD and β-TCP-DCPD were obtained by adding a proper amount of curing water. The composition and structure of the two materials were analyzed by X-ray diffraction, the morphology was observed by scanning electron microscope, and the mechanical strength was tested by Instron5567 universal material test machine. These two kinds of materials were placed in simulated body fluid for detecting the weight loss ratio, soaked for 14 days and taken out for X-ray diffraction and scanning electron microscope detection.
    RESULTS AND CONCLUSION: X-ray diffraction findings indicated that these two kinds of materials both belonged to high-purity DCPD bone cement. Under the scanning electron microscope, β-TCP-DCPD bone cement had dense crystal structure, with less pore number; however, the HA-DCPD bone cement presented with finer grains, loose structure, and higher pore number. With the increase of curing time, the mechanical strength of two kinds of bone cements was correspondingly increased, but the compressive strength of β-TCP-DCPD bone cement was significantly higher than that of HA-DCPD bone cement (P < 0.05). In the simulated body fluid, the weight loss ratio of β-TCP-DCPD bone cement was significantly lower than that of HA-DCPD bone cement (P < 0.05). At 14 days after soaking in the simulated body fluid, a layer of spherical particles that was formed on the surface of both materials was identified as hydroxyapatite by scanning electron microscope observation and X-ray diffraction analysis. In summary, HA-DCPD bone cement has good biodegradability, excellent bioactivity and bone conductivity, but poor mechanical properties.
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    Preparation and characterization of printed magnesium scaffolds for bone tissue engineering
    Li Ying, Wu Quan, Tang Geng, Li Hong, Shang Li-yan
    2018, 22 (6):  827-832.  doi: 10.3969/j.issn.2095-4344.0054
    Abstract ( 390 )   PDF (1171KB) ( 561 )   Save
    BACKGROUND: The traditional methods for preparing magnesium scaffolds include casting, powder metallurgy and laser processing technology. But these methods have some defects in pore connectivity, structure complexity, and personalization. Therefore, it is of great importance to explore a new method for the preparation of porous magnesium scaffolds.
    OBJECTIVE: To investigate the preparation and characterization of porous magnesium scaffolds fabricated by three-dimensional (3D) printing technology.
    METHODS: A magnesium porous scaffold was prepared by 3D printing. The high-stability magnesium paste (consisting of magnesium powder, 2-hydroxyethyl cellulose, polyethylene glycol, glycerol trioleate, ammonia, deionized water and absolute ethanol) was extruded from the pneumatic extrusion printing system to construct the scaffold, which was then sintered under protective atmosphere. The scaffold microstructure was observed by scanning electron microscope. The phase composition of scaffold was observed by X-ray diffraction. The porosity was measured by drainage method. The compressive strength was measured by universal testing machine. The degradation was studied by immersing the scaffold in saline for 30 days, and the degradation rate and the pH value of soak solution were measured at regular intervals.
    RESULTS AND CONCLUSION: (1) The magnesium scaffold was piled up by cylindrical filaments, and both the sizes of filaments and the pores were (450±50) μm. Also, there were many micropores in the filaments that formed the secondary pores. The porosity of the scaffold was (65.0±2.5)% and the compressive strength was (0.87±0.15) MPa. The principal phase of the scaffold was magnesium. (2) The degradation of the scaffold continued with the soaking time, and the degradation rate showed a steady trend, which was (10±0.2) mm per year in average. The pH value of the soak solution increased in the first 5 days, and then the pH value was kept at 10.5±0.2. To conclude, 3D printing technology provides a new method for porous magnesium scaffold preparation and application in bone tissue engineering.
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    Influence of two different crosslinkers on physiochemical properties and bioactivity of a composite bone scaffold composed of beta-tricalcium phosphate and gelatin
    Pan Zhao-hui, Luan Zhao-xin, Gao Peng
    2018, 22 (6):  833-839.  doi: 10.3969/j.issn.2095-4344.0055
    Abstract ( 460 )   PDF (2892KB) ( 292 )   Save
    BACKGROUND: The physiochemical properties and bioactivity of composite scaffolds can be altered by different crosslinkers.
    OBJECTIVE: To compare the physiochemical properties and bioactivity of composite scaffolds composed of β-tricalcium phosphate and gelatin, which are crosslinked by 1% genipin or gluteraldehyde, respectively.
    METHODS: Porous scaffolds composed of β-tricalcium phosphate and gelatin were made by phase separation/freeze-drying technique. Crosslinking time was 72 hours when genipin acted as a crosslinker and 24 hours when glutaraldehyde as a crosslinker. Physiochemical properties including porosity, degree of cross-linking, in vitro swelling ratio, degradation rate and compressive strength were detected. Bioactivities analyses were performed through co-culturing rabbit periosteal osteoblasts with 25%, 50% and 100% scaffold extracts for 24, 48, 72 hours. The proliferation rate and cytotoxicity gradation were evaluated. In addition, bilateral 8-mm skull defects were made in 18 rabbits and repaired with scaffolds crosslinked by genipin or gluteraldehyde, respectively. Gross observation, X-ray analysis and histological observation were performed at 4, 8 and 12 postoperative weeks.
    RESULTS AND CONCLUSION: (1) The porosity, compressive strength and maximum compressive force showed no statistical difference between the two crosslinker groups. Compared with the gluteraldehyde group, higher degree of crosslinking and lower swelling ratio and degradation rate were observed in the genipin group (P < 0.05). (2) In the genipin group, less than 50% growth inhibition was observed when co-cultured with 100% scaffold extract for 24 hours. Thus, the cytotoxicity was graded as 2, and the remains were graded as 1 or 0. In the gluteraldehyde group, excessive 50% growth inhibition was observed when co-cultured with 100% scaffold extract for 24 hours, and the cytotoxicity was graded as 3. For 25% and 50% subgroups (culture for 24 hours) and 100% subgroup (culture for 48 hours), the cytotoxicity was graded as 2, and the remains were graded as 1. (3) X-ray and histological observation showed the in-growth of new bone tissues from the periphery of the defect and the scaffold degraded centripetally. New bone formation was better in the genipin group than the gluteraldehyde group at 8 and 12 postoperative weeks (P < 0.05). To conclude, both genipin and gluteraldehyde can be used as crosslinkers to prepare the composite bone scaffold composed of β-tricalcium phosphate and gelatin. Two scaffolds have similar physicochemical properties; however, the former has a superior bioactivity except for a longer time for crosslinking with genipin.
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    Polylactic acid/polyglycolic acid copolymer scaffolds carrying bone morphogenetic protein 2 gene enhanced adipose-derived stem cells promote cartilage defect repair
    Ruan Shi-qiang, Deng Jiang, Yan Ling, Huang Wen-liang
    2018, 22 (6):  840-845.  doi: 10.3969/j.issn.2095-4344.0056
    Abstract ( 338 )   PDF (1239KB) ( 325 )   Save
    BACKGROUND: Gene-enhanced tissue engineering can promote the proliferation and differentiation of seed cells, reduce allogeneic immunity, promote vascularization, and facilitate the repair of osteochondral defects.
    OBJECTIVE: To observe the effect of lentivirus-mediated human bone morphogenetic protein-2 (BMP-2) transfected rabbit adipose-derived stem cells (ADSCs) cultured on polylactic acid/polyglycolic acid copolymer scaffold (PLGA) on osteochondral defect repair.
    METHODS: Thirty male New Zealand rabbits were randomly divided into control group (n=15) and experimental group (n=15). Animal models of bilateral femoral cartilage defects were made in all rabbits. The experimental group was implanted with BMP-2-enhanced ADSCs/PLGA copolymer scaffold, and the control group was implanted with ADSCs/PLGA copolymer scaffold. In both groups, autologous osteochondral mosaicplasty was then performed. After 3 months of implantation, bone tissues at defect region were taken for biomechanical and proteoglycans detection. Histological observation was done at 3, 6, 12 months after implantation.
    RESULTS AND CONCLUSION: (1) The compressive modulus and proteoglycan content of the experimental group were significantly higher than those of the control group at 3 months after implantation (P < 0.01). (2) At 3, 6 and 12 months after implantation, with the increase of postoperative time, the joint surface in the experimental group became more and more smooth, the color became more and more shallow, and the healing degree of the defect increased to different extent. However, there were no obvious changes in the joint surface, color, morphology and histomorphology in the control group. To conclude, BMP-2-enhanced ADSCs/PLGA copolymer scaffold could significantly promote the repair of osteochondral defects.
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    Implanting two kinds of bone substitutes into the sockets after wisdom tooth extraction to recover alveolar bone height
    Li Yi-dan, Xu Nuo, Li Yue-ling, Yu Ming, Chen Jie, Li Xiao-jie
    2018, 22 (6):  846-851.  doi: 10.3969/j.issn.2095-4344.0057
    Abstract ( 683 )   PDF (998KB) ( 538 )   Save
    BACKGROUND: Bio-Oss bone substitutes have been shown to prevent bone resorption by slowing bone resorption, reducing bone resorption, and restoring the height of the alveolar ridge. However, most clinical studies focus on the efficacy within 1-3 months.
    OBJECTIVE: To compare the effects of two kinds of bone substitutes on the height of alveolar ridge and the periodontal tissue health status after implantation into the extraction socket of the wisdom tooth.
    METHODS: Forty patients with impacted mandibular teeth were randomly divided into two groups: Bio-Oss Collagen material was implanted in experimental group (n=20), and Bio-Oss bone replacement materials in control group (n=20). Cone-beam CT was retrospectively reviewed at 1, 3 and 12 months after implantation. Alveolar bone height, bone changes and the second molars mobility were examined. Meanwhile, healing status of tooth extraction and gingival mucosa as well as the material spills were observed.
    RESULTS AND CONCLUSION: (1) At 1 month after implantation, the gingival mucosa of both groups healed well without swelling. There was no spillover in the experimental group, while there were two cases of bone material spill in the control group. No tissues generated in the extraction socket and tooth loosening was observed in both groups. (2) At 3 months after implantation, the materials gradually degraded with no swelling and with generation of partial bone tissues in the experimental group, and the tooth mobility was improved. In the control group, there was also no swelling in the gums, and the materials degraded partially, but there was no presence of new bone and no improvement in the tooth mobility. (3) At 12 months after implantation, there was no swelling in the gums of the experimental group, obvious new bone tissues formed in the second molar with the presence of bone trabecula. The new bone tissues were integrated with the surrounding bone tissues. The crest of the alveolar ridge was located about 3 mm below the enamel cementum, the tooth mobility was restored to the level before extraction, and the chewing function recovered. In the control group, there was no swelling in the gums, and new bone tissues formed in the distal part of the molar, but the trabecular arrangement was not aligned. The crest of the alveolar was located about 3 mm below the enamel cementum, the tooth mobility returned to the pre-extraction level, and the chewing function was normal. (4) The height of the alveolar bone at 1 and 3 months after implantation was significantly higher in the experimental group than the control group (P < 0.01), while there was no significant difference between the two groups at 12 months after implantation. To conclude, implantation of Bio-Oss Collagen immediately after removal of the impacted wisdom tooth of the mandible is beneficial to alveolar bone height and bone quality recovery, and significantly improves the periodontal health of the second molar, but the long-term effect needs further observation.
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    Minocycline hydrochloride ointment is available for the treatment of peri-implantitis
    Liu Ou, Gao Zhu, Li Tao, Zhou Bo
    2018, 22 (6):  852-857.  doi: 10.3969/j.issn.2095-4344.0058
    Abstract ( 442 )   PDF (877KB) ( 255 )   Save
    BACKGROUND: In recent years, the topical use of antibiotics in periodontal pockets has become a new regimen for the prevention and treatment of peri-implantitis.
    OBJECTIVE: To analyze the effectiveness of minocycline hydrochloride ointment in the treatment of peri-implantitis.
    METHODS: Eighty cases of peri-implantitis, 38 males and 42 females, aged 20-32 years, were divided into two groups: experimental group (n=40) was given minocycline hydrochloride ointment into the bottom of periodontal pockets, once a week; and control group (n=40) was injected iodine glycerol into the bottom of periodontal pockets, once a week. Meanwhile, patients without peri-implantitis were selected as normal control group (n=40). After 4 weeks of treatment, we detected probing index, bleeding index, plaque index, detection of Prevotella melaninogenica and Streptococcus oralis in the two groups, and then statistically analyzed the clinical efficacy.
    RESULTS AND CONCLUSION: (1) Before the treatment, probing index, bleeding index, plaque index, and detection rates of Prevotella melaninogenica and Streptococcus oralis were all higher in the experimental group than the normal control group (P < 0.05), but there was no significant difference between the experimental group and the control group. (2) After 4 weeks of treatment, probing index, bleeding index, plaque index, and detection rates of Prevotella melaninogenica and Streptococcus oralis in the experimental and control groups were significantly lowered (P < 0.05), but still higher than those in the normal control group (P < 0.05). In addition, these indices were also significantly lower in the experimental group than the control group (P < 0.05). (3) The clinical efficiency of the experimental group after treatment was significantly higher than that of the control group (98% vs. 75%, P < 0.05). Taken together, minocycline hydrochloride ointment as an effective treatment for peri-implantitis can inhibit the colonization of Prevotella melaninogenica and Streptococcus oralis.
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    Restoration of maxillary premolars: a finite element analysis of three repair methods and four kinds of dental restoration materials
    Fu Hong-yu, Feng Guang-zhi
    2018, 22 (6):  858-864.  doi: 10.3969/j.issn.2095-4344.0059
    Abstract ( 500 )   PDF (919KB) ( 432 )   Save
    BACKGROUND: Prognosis in tooth restoration is affected by different repair methods due to the different biomechanical effects.
    OBJECTIVE: To analyze three kinds of repair methods and four kinds of repair materials by using three-dimensional finite element analysis.
    METHODS: Tomographic images of isolated human maxillary first premolars were obtained by Micro CT scanning with a thickness of 0.019 mm. The Mimics output point cloud was used to generate the surface in Geomagic studio and the tooth model was generated respectively. The model was introduced into ABAQUS 6.13 software for Boolean operation, to simulate Inlay, Onlay of the medullary cavity retention type, and Core & Crown repair model. After the grid was divided into four ways of mechanical loading, six-point vertical loading or two-point loading at an angle of 0o, 45o, 90o with the long tooth shaft was done. The loading force was 75 N at each point. Four repair materials, cobalt-chrome, pure titanium, zirconia, IPS e.MAX, were used in this study.
    RESULTS AND CONCLUSION: (1) Under the four loading conditions of the same material, the maximum principal stress in the remaining dentin after Inlay restoration was the highest, followed by the Onlay repair and Core&Crown group. (2) Under the four loading conditions via the same approach, the maximum principal stress of the cobalt-chrome alloy in the enamel was the largest, and that of the IPS e.MAX porcelain was the smallest after repair. (3) The stress distribution of the parts was uniform after tooth restoration with the Core & Crown and the Onlay. To conclude, from the stress distribution, the Core&Crown and the Onlay are two ideal methods. Moreover, from the aspects of stress distribution and dentin preservation, Onlay is a more rational and safer way for large-area tooth defects. 
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    Preparation of a controlled-release icariin/beta-tricalcium phosphate composite scaffold
    Xue Peng, Du Bin, Wang Li-ning, Cao Liang-quan, Sun Guang-quan, Liu Xin, Yu Heng-heng
    2018, 22 (6):  865-870.  doi: 10.3969/j.issn.2095-4344.0060
    Abstract ( 418 )   PDF (2539KB) ( 304 )   Save
    BACKGROUND: Icariin can promote bone formation and inhibit bone resorption, but it is difficult to dissolve in water, and its bioavailability is very low in vivo. Therefore, a suitable carrier is essential to fully utilize the biological activity of icariin.
    OBJECTIVE: To prepare an icariin/β-tricalcium phosphate (β-TCP) composite scaffold and to characterize its biological characteristics.
    METHODS: Three-dimensional printing technology was utilized to prepare porous β-TCP scaffolds carrying nano zinc oxide, and the compressive strength of porous β-TCP scaffolds was detected before and after addition of nano zinc oxide. Water absorption and porosity of the porous β-TCP scaffolds were also measured. Ultrasonic emulsification solvent dialysis was performed to prepare icariin/   poly(lactic-co-glycolic acid) (PLGA) microspheres, followed by the detection of water absorption and porosity. The porous β-TCP scaffolds and icariin/PLGA microsphere suspension were mixed to prepare icariin/β-TCP composite scaffolds. Microstructure observation of the composite scaffolds was done by scanning electron microscope, and meanwhile, water absorption and porosity were detected. The composite scaffold was then immersed into PBS, and icariin concentration in the supernatant was measured at corresponding time points, based on which Icariin cumulative release curve was drawn.
    RESULTS AND CONCLUSION: (1) The porous microstructure of the porous β-TCP scaffold was regular, well distributed, and the connectivity was good. The pore spacing was about 600 μm. After addition of nano zinc oxide particles, the surface structure of the scaffold was more compact and the crystallinity was higher. (2) PLGA microspheres were spherical with a diameter of 1-4 μm, and the microspheres were uniform in size. (3) The maximum compressive strength of the porous beta tricalcium phosphate scaffold was (2.98±0.78) MPa, and increased to (8.95±0.29) MPa after addition of nano zinc oxide. (4) The water absorption rate and porosity were (25.09±0.96)% and (66.93±2.84)% for the porous β-TCP scaffold, (28.46±1.85)% and (32.65±3.32)% for the icariin/β-TCP composite scaffold, respectively. (5) The average encapsulation efficiency of the PLGA microspheres was (78.87±2.31)%, and the drug loading was (6.04±1)%. (6) The release amount of icariin could reach 52% of the total amount at 16 days and 60% of the total amount at 32 days. These findings indicate that the icariin/β-TCP composite scaffold has good mechanical properties and sustained-release performance.
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    Application of microsutures with vascular endothelial growth factor to improve vascular endothelial regeneration after small vessel anastomosis in the rats
    Zhang Tie-hui, Liang Wu, Ren Yuan-fei, Dong Yu-jin, Yang Wen-feng, Shang Yao-hua, Li Ju-tao, Zhong Sheng
    2018, 22 (6):  877-882.  doi: 10.3969/j.issn.2095-4344.0062
    Abstract ( 681 )   PDF (2550KB) ( 295 )   Save
    BACKGROUND: The vascular endothelial growth factor (VEGF) plays an important role in the development and formation of blood vessels. Up to now, there are few reports about the treatment of postoperative complications of vascular anastomosis surgery by mcrosutures with VEGF in China.
    OBJECTIVE: To synthesiize microsutures with VEGF and to evaluate its effect in revascularization following small vessel anastomosis.
    METHODS: The method of emulsification-diffusion was use to produce biodegradable polymer polylactic acid/glycolic acid (PLGA) copolymer microparticles containing VEGF, and then, the microparticles were added into microsutures to prepare microsutures with VEGF. Ninety Sprague-Dawley rats were enrolled to make animal models of caudal artery anastomosis using microsutures with VEGF in experimental group and microsutures alone in control group. Complications and VEGF level in the peripheral blood were detected and hematoxylin-eosin staining at the anastomotic site was performed at 2, 12 hours, 1, 3, 7 days after anastomosis.
    RESULTS AND CONCLUSION: (1) Postoperative complications: The postoperative incidence of skin necrosis was significantly lower in the experimental group than the control group (P < 0.05). (2) VEGF level: Compared with the control group, the peripheral blood VEGF level was significantly higher in the experimental group at each time point after operation (P < 0.05). (3) Hematoxylin-eosin staining: In the experimental group, proliferated endothelial cells were seen near the anastomotic site at 1 day after anastomosis; there were a large number of proliferated endothelial cells and subcutaneous tissues covering the sutures completely at 3 days after anastomosis; and endothelial cells and internal elastic lamina were completely repaired, smooth muscle cells proliferated further, and the outer membrane returned to normal at 1 week after anastomosis. In the control group, cell degeneration and necrosis were seen near the anastomotic suture, and only adventitial cells infiltrated and exhibited a traumatic proliferative response at 1 day after anastomosis; neonatal endothelial cells appeared in the exfoliated area of the endothelial cells, grew and migrated, and there was a few endothelial cells covering the anastomotic site at 3 days after anastomosis; and newborn endothelial cells got over the anastomotic crack and covered the suture. To conclude, microsutures with sustained-release VEGF microparticles can promote endothelial cell regeneration in rats at the anastomotic site.  
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    A targeting photodynamic drug vehicle composed of neural stem cells and mesoporous silica nanoparticles for tumor therapy
    Zhang Wei-jia, Chen Jia-shu
    2018, 22 (6):  883-888.  doi: 10.3969/j.issn.2095-4344.0063
    Abstract ( 518 )   PDF (1044KB) ( 470 )   Save
    BACKGROUND: Neural stem cells (NSCs), which exert no promoting effect on tumor growth and break through the blood brain barrier to deliver drugs into tumor tissues, are considered as a promising tumor targeted drug delivery vehicle.
    OBJECTIVE: To develop a hybrid delivery system composed of NSCs and moseporous silica nanoparticles for photosensitizer delivery, and to test if the system can be used for tumor therapy.
    METHODS: The photosensitizer, zinc phthalocyanine, was encapsulated in mesoporous silica nanoparticles. (1) Cytophagy experiment: NSCs were incubated with mesoporous silica nanoparticles (0, 10, 50, 100, 200 mg/L) loaded with zinc phthalocyanine for 6 hours, and fluorescence microscope was employed to observe the nanoparticles inside the cells. (2) Cytotoxicity test: NSCs incubated with mesoporous silica nanoparticles at various concentrations (0, 10, 50, 100, 200 mg/L) which loaded with or without zinc phthalocyanine for 6 hours, followed by 3 days of normal culture. Then, the cells were harvested for MTT assay. (3) Retention of nanoparticles within the NSCs: 100 mg/L mesoporous silica nanoparticles loaded with zinc phthalocyanine were co-cultured with NSCs for 6 hours. Then, the cells were normally cultured for 12, 24, and 72 hours, and observed with fluorescence microscope. (4) Zinc phthalocyanine excitation in vitro: 100 mg/L mesoporous silica nanoparticles loaded with or without zinc phthalocyanine were co-cultured with NSCs for 6 hours. The cells were then normally cultured for 12 hours and irradiated with laser. Microscope was employed to observe cell morphology. (5)Tumor cell killing experiment: NSCs cells were cultured with 100 mg/L mesoporous silica nanoparticles loaded with zinc phthalocyanine, then mixed with MCF7 cells for 12 hours, and irradiated with laser. After that, the cells were cultured for another 12 hours and cell death was observed under fluorescence microscopy.
    RESULTS AND CONCLUSION: (1) After co-cultured with the cells for 6 hours, nanoparticles could be found in the cytoplasm and the number was increased with the concentration of nanoparticles. (2) The nanoparticles with or without zinc phthalocyanine loaded at the concentration of < 100 mg/L showed no toxicity to NSCs. (3) After 72 hours of co-culture, the nanoparticles in the cytoplasm was decreased in number, but still could be found. (4) Laser irradiation could damage the cell membrane of NSCs co-cultured with mesoporous silica nanoparticles loaded with zinc phthalocyanine. (5) A large number of MCF7 cells died after tumor cells were co-cultured with NSCs that were cultured with mesoporous silica. To conclude, the hybrid system composed of NSCs and mesoporous silica nanoparticles loaded with zinc phthalocyanine can serve as a great potential tumor-targeted delivery vehicle for photodynamic therapy. 
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    Preparation and performance properties of functionalized multi-walled carbon nanotubes/chitosan-zinc composite scaffolds
    Yang Ben, He Dong-ning, Qin Bo-heng, Zhang Bao-ping
    2018, 22 (6):  889-895.  doi: 10.3969/j.issn.2095-4344.0064
    Abstract ( 399 )   PDF (1083KB) ( 237 )   Save
    BACKGROUND: A pure chitosan (CS) scaffold has poor mechanical properties, and cannot play a load-bearing role in the bone defect region. Therefore, many scholars attempt to develop multi-walled carbon nanotube (MWCNT)/chitosan (MWCNT/CS) bone tissue scaffolds.
    OBJECTIVE: To develop the functionalized MWCNT/CS composite scaffolds carrying zinc (f-MWCNT/CS-Zn) and to test its mechanical properties, antibacterial activity and biocompatibility.
    METHODS: (1) F-MWCNT composite scaffolds were prepared by the acid mixture method, and f-MWCNT/CS-Zn composite scaffolds were prepared through mixing CS, f-MWCNT (0.5%) with different concentrations of ZnSO4•7H2O (the concentrations of Zn in the composite scaffolds were 0.2%, 1%, 2%, respectively). The surface hardness and tensile strength of the pure CS scaffold and the f-MWCNT/CS-Zn composite scaffolds were measured. (2) The inhibitory effect on Staphylococcus aureus or Escherichia coli of the pure CS scaffold and f-MWCNT/CS-Zn scaffolds was tested by inhibition zone test. (3) The osteoblasts MC3T3-El were cultured with the leaching solution of f-MWCNT/CS-Zn composite scaffolds. The cell proliferation was detected by MTT assay at 1, 2, 3 days after culture, then the relative proliferation rate was calculated and the cytotoxicity was evaluated.
    RESULTS AND CONCLUSION: (1) The surface hardness and tensile strength of the f-MWCNT/CS-Zn composite scaffolds were higher than those of the pure CS scaffold (P < 0.05), and there was no significant difference in the surface hardness and tensile strength between the different zinc-containing composite scaffolds. (2) The antibacterial properties of the three f-MWCNT/CS-Zn composite scaffolds against Staphylococcus aureus and Escherichia coli were higher than those of the pure CS scaffold (P < 0.05), and the antibacterial activity was enhanced with the increase of zinc mass fraction. (3) The f-MWCNT/CS-0.2%Zn and f-MWCNT/CS-1%Zn composite scaffolds had no cytotoxicity. To conclude, the f-MWCNT/CS-1%Zn composite scaffold has good mechanical properties, antibacterial activity and biocompatibility.
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    Effect of mixed acid reflux time on purification and biocompatibility of large-inner-diameter multi-walled carbon nanotubes
    Meng Ai, Wang Jian, Sui Lei
    2018, 22 (6):  896-901.  doi: 10.3969/j.issn.2095-4344.0065
    Abstract ( 381 )   PDF (1133KB) ( 453 )   Save
    BACKGROUND: A mass of debris particles that can lead to cytotoxicity exist in commercial large-inner-diameter multi-walled carbon nanotubes (LID-MWCNTs). Because of the high hydrophobicity on the surface of the tube wall, the carbon tubes can be twisted and agglomerated, resulting in the low dispersion and poor biocompatibility. Therefore, to explore the effective methods of purifying and modifying LID-MWCNTs is the primary problem to develop its potency in the biomedical application.
    OBJECTIVE: To explore the effects of different mixed acid reflux time on LID-MWCNTs purification and biocompatibility.
    METHODS: After pretreatment with high temperature calcinations and hydrochloric acid pickling, LID-MWCNTs were purified under different time of mixed acid reflux time (1, 2, 4 hours). The mixed acid reflux time for best purification was chosen based on surface morphology and dispersibility, so as to optimize preparation technology and observe the characterization. The L929 cells and CAL-27 cells were treated with different concentrations of raw LID-MWCNTs (5, 10, 20, 40, 80 mg/L) and purified LID-MWCNTs by mixed acid reflux (5, 10, 20, 40, 80 mg/L). After 72 hours, cell counting kit-8 assay was employed to test the proliferation of L929 cells and CAL-27 cells.
    RESULTS AND CONCLUSION: (1) With the time of mixed acid reflux, the length of LID-MWCNTs was decreased, and the dispersion was improved. However, the external surface of the tubes after mixed acid reflux 2 and 4 hours were destroyed obviously. Especially after mixed acid reflux 4 hours, the tubes were destroyed seriously and the diameter of tubes was not uniform. However, after mixed acid reflux 1 hour, the fundamental structure and morphology of the tubes were not changed, the debris particles were undetected on the tube wall surface, and the tubes had the good dispersion. (2) Under the same concentration, the survival rate of L929 cells in the raw LID-MWCNTs group was lower than that in the purified LID-MWCNTs group. At the concentration of 10-80 mg/L, the survival rate of L929 cells in the group of mixed acids reflux 1 hour was up to 90%, higher than that in the other groups (P < 0.05). (3) Under the same concentration, the survival rate of CAL-27 cells in the raw LID-MWCNTs group was lower than that in the purified LID-MWCNTs. At the concentration of 20-80 mg/L, the survival rate of CAL-27 cells in the group of mixed acids reflux 1 hour was up to 90%, higher than that in the other groups (P < 0.05). These results revealed that the raw LID-MWCNTs were purified effectively after mixed acid reflux 1 hour, and the cytotoxicity was decreased.
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    Mechanical properties and cytocompatibility of a new-type nano-bionic anti-adhesion hernia mesh
    Tang Xiao, Ye Xiao-long, Huang Jiang-long, Yang Xiao-feng, Zheng Zong-heng, Wei Bo, Chen Tu-feng, Huang Yong, Luo Lin-bo, Zhan Ze-feng, Wei Hong-bo
    2018, 22 (6):  902-907.  doi: 10.3969/j.issn.2095-4344.0066
    Abstract ( 375 )   PDF (1055KB) ( 425 )   Save
    BACKGROUND: A new-type nano-bionic anti-adhesion hernia mesh was developed in our previous research.
    OBJECTIVE: To investigate the mechanical properties and cytocompatibility of the new-type nano-bionic anti-adhesion hernia mesh.
    METHODS: The tensile strength of the compound hernia mesh was detected using a textile detector. Mouse fibroblasts (L929) were cultured with the compound hernia mesh, and cell structures on the mesh surface were observed under electron microscope at 1, 3, 5 days after culture. In addition, L929 cells were co-cultured with compound hernia mesh, polypropylene patch, and polyester patch, respectively. Cells cultured alone were used as negative controls. After 1, 3, 5 days of culture, MTS array was used to detect cell proliferation and evaluate cytotoxicity; after 3 days of culture, western blot was used to detect the content of type I and III collagens.
    RESULTS AND CONCLUSION: The average tensile strength of the compound hernia mesh was 31.2 N. The number of fibroblasts on the nanofibrous layer of the compound hernia mesh increased as long as cultured. The cells spread along the nanofibers and pseudopodia extended from the cells formed polygon and fusiform structures, with a good cross-linking with the mesh. A complete cell layer covered all pores of the nanofibers at 5 days. The cytotoxicity of the nanofibrous layer of the compound hernia mesh was graded 0, and the cytotoxicity was graded 1 of polypropylene and polyester patches. All the three kinds of patches fulfilled the implantation requirements, and the compound hernia mesh had better biological properties. No significant differences were found among groups in the contents of type I and III collagens at 3 days of culture. To conclude, the new-type nano-bionic anti-adhesion hernia mesh has good mechanical properties and cytocompatibility.
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    Self-fixating polypropylene/poly(lactic acid) mesh for treatment of chronic pain following tension-free repair of inguinal hernia
    Huang Liang, Yu Zhuang-ming, Li Jun, Li Chang-wei
    2018, 22 (6):  908-913.  doi: 10.3969/j.issn.2095-4344.0067
    Abstract ( 491 )   PDF (810KB) ( 405 )   Save
    BACKGROUND: Increasing clinical studies have reported the application of self-fixating mesh in the tension-free repair of inguinal hernia, but whether the self-fixating mesh is superior to the common suture mesh is still in dispute.
    OBJECTIVE: To compare the effects of self-fixating polypropylene/poly(lactic acid) mesh and polypropylene mesh on chronic pain after tension-free repair of inguinal hernia.
    METHODS: A total of 90 male patients with primary inguinal hernia were randomly divided into two groups: self-fixating mesh and control groups (n=45 per group). All patients underwent tension-free hernioplasty followed by self-fixating polypropylene/poly(lactic acid) mesh in the self-fixating mesh group and polypropylene mesh in the control group. Operation time and length of hospital stay were recorded; complications and recurrence rate in the two groups were observed at 6 months after operation; and postoperative pain and chronic pain were assessed by the visual analog scale (VAS) at postoperative 1, 10 days, 1, 3, 6 months.
    RESULTS AND CONCLUSION: (1) Compared with the control group, the operation time was shorter in the self-fixating mesh group (P < 0.05), but there was no significant difference in the length of hospital stay between the two groups. (2) The VAS scores showed no significant difference between the two groups at postoperative 1 day, but the VAS scores were significantly better in the self-fixating mesh group than the control group at 10 days, postoperative 1, 3, 6 months (P < 0.05). (3) During the 6-month follow-up, there were no urinary retention, subcutaneous hematoma, wound infection and recurrence in the two groups except five patients in the control group who complained of a foreign body sensation. To conclude, compared with the traditional polypropylene mesh, the use of self-fixating polypropylene/poly(lactic acid) mesh can shorten operation time and reduce pain and discomfort of patients with unilateral inguinal hernia undergoing tension-free hernioplasty.
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    Biocompatibility of basic fibroblast growth factor-poly(lactic-co-glycolic acid) microspheres/ hydroxyapatite/poly(l-lactic acid) porous materialsBiocompatibility of basic fibroblast growth factor-poly(lactic-co-glycolic acid) microspheres/ hydroxyapatite/poly(l-lactic acid) porous materials
    Li Zhi-yue, Zhu Zhi-bo, Zhao Qun, Xiang Si-yu, Zhao Peng, Xu Zhe-wei
    2018, 22 (6):  914-920.  doi: 10.3969/j.issn.2095-4344.0068
    Abstract ( 459 )   PDF (2342KB) ( 272 )   Save
    BACKGROUND: To date, no single material can completely meet the clinical requirements. However, the composite materials characterized by good biodegradability, biocompatibility and osteoconductivity have become a highlight of the artificial bone materials.
    OBJECTIVE: To synthesize the basic fibroblast growth factor (bFGF)-poly(lactic-co-glycolic acid) (PLGA) microspheres/hydroxyapatite (HA)/poly(l-lactic acid) (PLLA) porous bone scaffolds, and to observe the physicochemical properties and biocompatibility of the composite material.
    METHODS: The bFGF-PLGA microspheres were prepared by double emulsion method, and then six kinds of materials were made including PLLA, PLLA/HA, PLLA/PLGA, PLLA/HA/PLGA, PLLA/HA/bFGF, and bFGF-PLGA microspheres/PLLA/HA. The characterization of the materials were observed by particle size analyzer, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrometer, microcomputer differential thermal balance, and scanning electron microscope. Toxicity of these materials and proliferation of bone marrow mesechymal stem cells seeded onto these materials were analyzed and compared.
    RESULTS AND CONCLUSION: The average particle size of bFGF-PLGA microspheres was about 250 nm, the average drug-loading capacity was (26.03±0.17)%, and the entrapment percentage was (90.65±2.68)%. The prepared bFGF-PLGA microspheres were spherical and had good dispersibility. In addition, all the six kinds of materials had a porous structure with similar pore diameter, in which the microspheres and particles exhibited a rational distribution. The toxic level of bFGF-PLGA microspheres/PLLA/HA, bFGF/HA/PLLA and HAP/PLLA was graded as 1 (with a relative survival rate ≥ 80%), indicating no obvious toxicity or slight toxicity. All these six kinds of composite materials can promote the proliferation of bone marrow mesenchymal stem cells, and the bFGF-PLGA microspheres/PLLA/HA shows the best effects on cell proliferation and has good biocompatibility. 
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    Autologous platelet-rich plasma in combination with tendon stem cells to treat tendinopathy in a rabbit model: histomorphological changes of the tendon tissue and matrix metalloproteinase 1 expression
    Xian Jie, He Ben-xiang, Wu Xiao, Tan Ya-jun
    2018, 22 (6):  921-926.  doi: 10.3969/j.issn.2095-4344.0069
    Abstract ( 396 )   PDF (2341KB) ( 288 )   Save
    BACKGROUND: The research and application of platelet-rich plasma in tissue regeneration and restoration have always been an issue of concern in the medicine and bioengineering fields.
    OBJECTIVE: To analyze the effects of platelet-rich plasma in combination with tendon stem cells on histomorphology change and matrix metalloproteinase 1 expression of the tendon tissues in a rabbit model of Achilles tendinopathy.
    METHODS: Forty New Zealand white rabbits were randomly divided into model group (n=32) and blank control group (n=8). In the model group, the animals were injected about 2 cm distant to the attachment point of the left calcaneus with prostaglandin E2 (once a week, for totally 4 weeks) to make the animal model of tendinopathy. The rabbits in the blank control group were injected the equal amount of normal saline. After 4 weeks, model rabbits were randomly divided into four subgroups: combination group, tendon stem cell group, platelet-rich plasma group and model control group, with eight rabbits in each group. Platelet-rich plasma and tendon stem cells, alone or in combination, and normal saline were injected into the corresponding group, twice with an interval of 3 weeks. At 6 weeks after injection, the tendon tissue was collected and stained for histological examination and detection of matrix metalloproteinase 1 expression.
    RESULTS AND CONCLUSION: (1) Hematoxylin-eosin staining: the tendon fibers in the combinationgroup were intact and arranged orderly; in the tendon stem cell group, the tendon fibers were almost arranged orderly despite some fractured fibers; in the platelet-rich plasma group, fiber breakage and loose fiber structure were observed; in the model control group, there were no intact tendon fibers, with the presence of inflammatory cell filtration. (2) Masson staining: The tendon fibers in the combination group had slight wave-shaped changes but the fibers were not cut off; in the tendon stem cell group, the tendon fibers were slightly in disorder, but with the intact structure, and obvious inflammatory cell filtration was observed; in the platelet-rich plasma group, fiber breakage, reduced collagen fibers and inflammatory cell filtration were obviously observed; in the model control group, there were no intact tendon fibers, and inflammatory cell filtration was clearly visible. (3) The expression of matrix metalloproteinase 1: Compared with the blank control group, the expression of matrix metalloproteinase 1 was significantly higher in the other groups except the combination group (P < 0.05). There was no significant difference in the expression of matrix metalloproteinase 1 between the combination group and blank control group (P > 0.05). To conclude, the combination of platelet-rich plasma and tendon stem cells can inhibit the vicious cycle of degeneration of collagen and extracellular matrix, reduce the expression of matrix metalloproteinase 1 in tenocytes, and delay inflammation responses and degeneration due to tendinopathy.
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    Detection of residual diphenylmethane diisocyanate monomer in a hemodialysis catheter
    Huang Yuan-li, Sun Xue, Ke Lin-nan, Wang Chun-ren
    2018, 22 (6):  927-931.  doi: 10.3969/j.issn.2095-4344.0070
    Abstract ( 617 )   PDF (727KB) ( 707 )   Save
    BACKGROUND: In the current quality control file or technical standards of the hemodialysis catheter, the indicators of the component contents and detection methods of the residual diphenylmethane diisocyanate (MDI) monomer are undefined. To ensure the safety and effectiveness of these products, we should try to establish and improve the quality standards.
    OBJECTIVE: To establish a method for determination of the residual MDI monomer in a hemodialysis catheter by gas chromatography (GC), and to analyze the bio-security of the MDI.
    METHODS: Samples collected in the hemodialysis catheter were heated to reflux with ethyl acetate and the residual MDI content was analyzed by the GC. The GC separation was performed on a DB-5 MS column (30 m×0.25 mm), the temperature of which rose by program. The initial temperature was 60 ℃, maintained for 5 minutes, rose to 280 ℃ with a rate of 15 ℃/min, and maintained for 6 minutes. The temperature of the Injector and FID detector was both 280 ℃. Carrier gas was 99.999% nitrogen.
    RESULTS AND CONCLUSION: The linearity was achieved in the range of 4.970-99.40 mg/L (r=0.999 64) for MDI. The mean recovery rate was 100.9% with the relative standard deviation of 3.2% (n=6). The residue of MDI monomer in the three batches of samples was lower than the tolerable exposure. Therefore, it is a sensitive, rapid, accurate, specific method that can be used for the quality control of the residual MDI monomer in the hemodialysis catheter. 
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    Preparation and performance detection of small-diameter tissue-engineered blood vessels
    Ma Xiao-long, Li Wen-bin, Xin Zhi-fei, Li Dian-kun, Zhou Zi-fan, Wan Ju-yi, Wang Jian-gang
    2018, 22 (6):  932-937.  doi: 10.3969/j.issn.2095-4344.0071
    Abstract ( 489 )   PDF (835KB) ( 346 )   Save
    BACKGROUND: Due to limited sources, poor hemocompatibility and poor anticoagulation performance, small-diameter tissue-engineered blood vessels cannot be applied in clinical practice.
    OBJECTIVE: To explore the physicochemical and mechanical properties of sheep carotid arteries after the decellularization in order to find appropriate materials for the preparation of tissue-engineered blood vessels.
    METHODS: Fresh carotid arteries from sheep were randomly divided into two groups: control group, in which, the sheep carotid arteries were cryopreserved for use after trimming and cleaning; experimental group, in which, after trimming and cleaning, the carotid arteries were decellularized by Triton X-100, sodium deoxycholate and EDTA for 24 hours, rinsed for 72 hours, digested with RNA/DNA enzymes for 24 hours, rinsed for 24 hours and reserved for later use. In both groups, blood samples were subjected to hematoxylin-eosin staining, collagen fiber staining, elastic fiber dyeing, and electron microscopy observation. The physical and chemical properties of the blood vessels are tested by tensile strength, wall tension and thickness.
    RESULTS AND CONCLUSION: (1) The collagen fibers in both two groups were neat and compact in alignment, with no obvious fracture.
    (2) Hematoxylin-eosin staining showed that: in the control group, the nuclei were distributed in the inner membrane, middle lamella and outer membrane of the vessels, and the fibers ran regularly; in the experimental group, the fibers ran in order but loosely, and there were no nuclei in the inner membrane, middle lamella and outer membrane of the vessels. (3) Elastic fibers in the control group were regular in alignment and mainly distributed in the middle lamella and outer membrane of the vessels, while in the experimental group, the elastic fibers ran regularly but loosely, and mainly distributed in the middle lamella and outer membrane of the vessels. (4) Under the scanning electron microscope, the originally formed vessels were observed in the experimental group, with no cell residues, and the collagen fibers ran orderly with no fracture and with uniform pore structure. (5) The vessel thickness was lower in the experimental group than the control group (P < 0.01), but the tensile strength showed no difference between the two groups, which was 46.55 kPa in the two groups. To conclude, the decelluarized sheep carotid artery can retain the necessary mechanical properties of the blood vessels after achieving the maximum removal of antigenicity.
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    Synthesis and biological properties of strontium-substituted hydroxyapatite
    Dai Zhao, Wang Da-lin
    2018, 22 (6):  938-944.  doi: 10.3969/j.issn.2095-4344.0072
    Abstract ( 438 )   PDF (956KB) ( 427 )   Save
    BACKGROUND: Hydroxyapatite is the main mineral component of bone and teeth. It is non-immunogenic and osteoinductive and suitable for bone repair. Strontium and calcium are cognate elements in the periodic table of elements and it has been proved that strontium has dual effects, namely, osteogenic promotion and suppression of osteoclast activity.
    OBJECTIVE: To summarize the preparation of strontium-substituted hydroxyapatite and its biological properties.
    METHODS: The first author searched the PubMed database for related literature from 1990 to 2017. The key words were "strontium; substituted; doped; containing; hydroxyapatite". The literatures obtained were screened, and the irrelevant and repetitive literatures were excluded.
    RESULTS AND CONCLUSION: The preparation methods of strontium-substituted hydroxyapatite include liquid-phase method (hydrothermal method, acid-base neutralization and sol-gel method) and solid-phase method (mechanochemical method). In addition, strontium-substituted hydroxyapatite coating can be produced by electrochemical deposition and micro-arc oxidation. The introduction of strontium significantly modifies the crystal size, crystallinity, solubility and mechanical properties, and improves the biocompatibility, pro-osteogenesis and osteoclast inhibition of hydroxyapatite, but the optimal proportion of strontium needs to be further explored. Furthermore, the immune-regulation and osteogenic properties under pathological conditions of strontium-substituted hydroxyapatite need to be further improved.
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    Macromolecular crowding agents for the extracellular matrix: mechanisms and unfavorable factors to be comfirmed
    Geng Ying-nan, Wu Ding-yu, Zhang Zhi-yong, Wei Min
    2018, 22 (6):  945-951.  doi: 10.3969/j.issn.2095-4344.0073
    Abstract ( 398 )   PDF (1056KB) ( 258 )   Save
    BACKGROUND: Macromolecule crowding agents exert a certain effect on collagen, glycosaminoglycans and growth factors in the extracellular matrix.
    OBJECTIVE: To summarize the effects of macromolecule crowding agents on the extracellular matrix and their applications in various cells or tissues.
    METHODS: “Macromolecular crowding, MMC, Tissue Engineering, Collagen” were used as key words to retrieve articles addressing the application of macromolecular crowding agents in the extracellular matrix and in the tissue engineering in PubMed, NCBI, CNKI from 2001 to 2017.
    RESULTS AND CONCLUSION: Macromolecule crowding agents can increase the deposition of extracellular matrix components, such as collagen, glycosaminoglycans and growth factors, to promote osteoblast adhesion, migration, growth and differentiation, as well as to promote the development of regenerative medicine in bone tissue engineering. However, some roles and mechanisms of macromolecule crowding agents have yet to be found or confirmed, and whether they can produce toxic effects in the human body has yet to be confirmed. Therefore, further experimental research on these problems is warranted.
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    Silk fibroin/chitosan scaffolds for corneal tissue engineering: theoretical development and applications
    Wang Jia-qi, Zhang Wen-fang
    2018, 22 (6):  952-957.  doi: 10.3969/j.issn.2095-4344.0074
    Abstract ( 490 )   PDF (747KB) ( 262 )   Save
    BACKGROUND: Keratitis, chemical injury, trauma, and other diseases often lead to irreparable damage to the corneal tissue, which can cause scars and finally vision loss. Corneal transplantation is the only way for treatment, but is of limit use by the deficiency of donors. Moreover, biosynthetic implants are expensive and complex. Silk fibroin and chitosan are common materials for tissue engineering and have been widely used as bio-scaffold materials. However, the technology applied in corneal repair is still in infant stage.
    OBJECTIVE: To systemically analyze the literature regarding the application of silk fibroin/chitosan scaffold materials in corneal repair, and to offer new directions and theoretical support for further studies on corneal repair.
    METHODS: A computer-based search of CNKI, WanFang and PubMed was performed for relevant articles with the keywords of “silk fibroin, chitosan, cornea, keratoprosthesis, scaffold”. Then, we traced the development progress of silk fibroin/chitosan scaffolds in corneal repair and summarized its current applications and prospects.
    RESULTS AND CONCLUSION: In total, 178 articles were preliminarily retrieved, and finally, 52 eligible articles were reviewed. (1) The silk fibroin/chitosan scaffold for corneal repair has low cytotoxicity and good biocompatibility. (2) This kind of scaffold supplies proper pericellular environmental for corneal cells that is good for hydroelectrolyte exchange. (3) The presence of ABCG2 protein implies that the scaffold offers possibilities of limbal stem cell proliferation. (4) Increasing animal model tests have shown that the scaffold can barely cause an inflammatory reaction of corneal cells, which is highy important to remain the vitreousness of corneal tissues. (5) Because of the deficiency of corneal donors, searching for new artificial materials for corneal repair is the developing direction of corneal transplantation. Silk fibroin chitosan scaffold has huge potential in this area, and it deserves more researches for clinical use in the future.
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    Actuality and challenge of biomaterials in annulus fibrosus repair
    Zhang Lei, Zhou Song, Cheng Bao-chang
    2018, 22 (6):  958-963.  doi: 10.3969/j.issn.2095-4344.0075
    Abstract ( 365 )   PDF (846KB) ( 262 )   Save
    BACKGROUND: Recently, tissue-engineered biomaterials for annulus fibrosus repair in the treatment of intervertebral disc degeneration have aroused wide attentions.
    OBJECTIVE: To investigate the research progress in biomaterials for the repair of annulus fibrosus in intervertebral disc tissue engineering.
    METHODS: PubMed database (1991-2017) was retrieved by the first author with the key words of “intervertebral disc, annulus fibrosus, material, scaffold” to search relevant articles about the use of biomaterials in annulus fibrosus repair.
    RESULTS AND CONCLUSION: Biomaterials play important roles in annulus fibrosus repair, which mainly function to recover the physical structure and mechanical function of the annulus fibrosus by promoting extracellular matrix secretion and tissue regeneration. Current materials mainly used for the repair of annulus fibrosus include natural materials, polymer materials, and biomaterials. Natural materials have good biocompatibility, biodegradability and no cytotoxicity, but their mechanical strength is poor. Polymer materials which overcome the lack of mechanical strength have repeatability, controllability, no immunogenicity, and are easy to be processed, but they have poor biocompatibility and cell affinity, as compared with the natural materials. Therefore, the selection of composite materials by integrating the advantages of different materials becomes the main trend in the annulus fibrosus repair.
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    Preparation and application of cardiac decellularized matrix scaffolds
    Wu Quan-hua, Chen Xu-xiang, Wang Lei, Wu Hao, Long Hui-bao, Hou Jing-ying, Wang Tong
    2018, 22 (6):  964-970.  doi: 10.3969/j.issn.2095-4344.0076
    Abstract ( 410 )   PDF (1592KB) ( 455 )   Save
    BACKGROUND: All-natural cardiac decellularized scaffold material has macroscopic and microstructure, matrix components and vascular network distribution similar to the receptor, which is an ideal material for heart tissue engineering.
    OBJECTIVE: To summarize the preparation methods, composition characteristics, biological characteristics and the latest research progress of cardiac decellularized matrix scaffold.
    METHODS: Relevant articles published from January 2008 to April 2017 were searched in PubMed and Wanfang databases using the keywords of “heart, cardiac muscle, myocardial tissue, decellularized matrix” in English and Chinese, respectively. Finally, 50 representative articles (44 in English and 6 in Chinese) were included with the exception of the articles that were associated with cardiac valves.
    RESULTS AND CONCLUSION: Currently, the methods of preparing cardiac decellular matrix scaffolds include physical processing, chemical method and biological treatment (enzymatic method). Cardiac extracellular matrix scaffolds mainly contain I, III and IV collagen, glycosaminoglycans, fibronectin, laminin and a small amount of growth factors. At present, the application of the decellular matrix in myocardial tissue engineering includes three directions: the "band-aid" myocardial tissue engineering study based on decellular matrix lamella; the study of the myocardial tissue engineering on injectable myocardial tissue engineering based on the decellular matrix; and the study of decellularized-recellularized artificial cardiac reengineering based on the cardiac all-organ. Although some successful experience has been achieved in the stents, their use in the cardiac replantation still has many problems to be solved.
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    Application of hydroxyapatite functional graded biomaterials in human hard tissue replacement
    Wei Wei, Shu Jing-ai, Wang Jing, Zheng Li-xia, Li Lu, Wang Qing-shan
    2018, 22 (6):  971-978.  doi: 10.3969/j.issn.2095-4344.0077
    Abstract ( 378 )   PDF (873KB) ( 444 )   Save
    BACKGROUND: Functional graded biomaterials promote the development of human hard tissue replacement.
    OBJECTIVE: To review the research progress of functional graded biomaterials in human hard tissue replacement.
    METHODS: The first author retrieved the PubMed and CNKI databases for relevant articles published from January 2010 to April 2017 using the keywords of “functional graded biomaterial, hard tissue replacement implants, preparation methods, performance evaluation, dental implants, osseous tissue” in English and Chinese, respectively.
    RESULTS AND CONCLUSION: Functional graded biomaterials refer to a kind of heterogeneous composite materials with controllable and programmable gradient properties on account of continuous or quasi-continuous changes in the structure and chemical composition. Hydroxyapatite is the primary choice for the material surface. Serving as an emerging biomaterial, the functional graded biomaterial has unique structure mechanism and excellent properties. It gives full play to the performance advantages of each component and reduces internal stress interface between components. Therefore, the functional graded biomaterial will be an issue of concern in the future because of the optimization of its design, preparation and performance.   
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    Poly(lactic-co-glycolic acid)-cycloserine microsphere preparation and in vitro release properties
    Bao Yu-cheng, Zhang Wen-long, Wang Yong, Yu Mei-li, Yang Xue-chun, Shen Jing
    2018, 22 (6):  971-976.  doi: 10.3969/j.issn.2095-4344.0061
    Abstract ( 360 )   PDF (926KB) ( 409 )   Save
    BACKGROUND: Cycloserine with low hepatotoxicity exhibits no cross-resistance with the existing anti-tuberculosis drugs, and has been commonly used for the treatment of drug-resistant tuberculosis. However, its oral administration or injection leads to a certain degree of neurotoxicity.
    OBJECTIVE: To prepare poly(lactic-co-glycolic acid) (PLGA)-cycloserine sustained-release microspheres which are expected to reduce the neurotoxicity and adverse reactions, and maintain the drug concentration in the bone tuberculosis region for a long time, and to observe the in vitro drug release of the microspheres.
    METHODS: Double emulsion solvent evaporation method was used to prepare PLGA-cycloserine microspheres that were bonded into sponge implant by Bletilla striata polysaccharide extract. Then, morphology, particle size, encapsulation efficiency and in vitro performance of the microspheres were observed. The drug loading, burst release, appearance and dispersion of the microspheres were observed at 0, 1, 2 months after the microspheres were placed in room temperature (25 ℃), high temperature (60 ℃) and high humidity (93%), respectively.
    RESULTS AND CONCLUSION: The PLGA-cycloserine microspheres that were round and spherical presented with the mean particle size of (143±38) μm, the drug loading of 38.38% and the encapsulation efficiency of 67.54%. No burst release occurred, and the cumulative release of drug within 50 days was 65.62%. After being stored at room temperature, high temperature and high humidity for 1 and 2 months, the microspheres were intact in the appearance and morphology, and showed insignificant changes in drug loading and burst release. To conclude, the time of degradation and the release of drug accord with the biological requirements of bone restoration.
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    Photosensitive resin used for 3D printing and its application in dentistry
    Zhu Li-sha, Chen Yu-ming, Li He-fei, Kang Hong
    2018, 22 (6):  979-984.  doi: 10.3969/j.issn.2095-4344.0078
    Abstract ( 942 )   PDF (1153KB) ( 1396 )   Save
    BACKGROUND: Nowadays, digitalization has become a major trend in the field of dentistry. It is highly important to apply 3D printing technology with the material of photosensitive resin to orthodontics, prosthodontics and so on.
    OBJECTIVE: To review the composition of photosensitive resin for 3D printing and its main commercial series, and to discuss about applications and prospects of photosensitive resin in the field of dentistry.
    METHODS: Using "3D printing, digitalization, photosensitive resin, dentistry" as key words in English and Chinese, the authors seareched the database PubMed and CNKI, respectively, for articles addressing the development of 3D printing technology, classification and composition of photosensitive resin as well as the progress and application of photosensitive resin in the field of dentistry over the past 15 years (1991-2016).
    RESULTS AND CONCLUSION: Because of achieving the visualization of data, having advantages such as personalized design printing, fast small batch production, efficient and free molding manufacturing and being easy to manufacture complex modeling products, 3D printing technology has been developed rapidly in various areas. Light-curing rapid prototyping technology (Stereo Lithigraphy Apparatus, SLA), based on photosensitive resin, is one of the most widely used technological processes of 3D printing. Photosensitive resin for 3D printing can be classified by composition and the main commercial series. At present, the development of photosensitive resin for 3D printing meets the demand of personalized design in the field of dentistry. It has been developed rapidly in orthodontics, prosthodontics, oral implantology, and oral internal medicine. It can be used in fixed denture, implanted surgical guide, base for removable denture and fused model manufacture. With the continuous expansion of the types of materials and improvement of material performance, digital dentistry will become a major trend in the future.
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