Large bone defect repair is a difficult problem to be solved urgently in orthopaedic field, and the application of bone repair materials is a feasible method to solve this problem. Therefore, bone repair materials have been continuously developed, and have evolved from autogenous bone grafts, allograft bone grafts, and inert materials to highly active and multifunctional bone tissue engineering scaffold materials. In this paper, the related mechanism of bone repair materials, the application of bone repair materials, and the exploration of new bone repair materials are introduced to present the research status and advance of the bone repair materials, and the development direction is also prospected.
Objective To evaluate the effect of methylation determination about the peripheral plasma DNA in diagnose of hepatocellular carcinoma （HCC） and select the highly sensitive and specific methylated cancer suppressor genes. Methods Methylation-specific PCR （MSP） was used to detect the degree of methylation about SLIT2 and DAPK genes in peripheral plasma and associated cancer tissues of 34 patients with HCC confirmed by pathology, then analyzed their relationship to clinicopathologic feature. Results The positive rate of the promoter methylation of SLIT2 and DAPK genes in cancer tissues in 34 cases were 70.6% （24/34） and 79.4% （27/34）, while the relevant promoter methylation rate in plasma were 44.1% （15/34） and 50.0% （17/34） correspondingly. The sensitivity of detection of DNA methylation about SLIT2 and DAPK genes in plasma was 62.5% and 63.0%, respectively；both of the specificity for them were 100%. The negative predicted value was 52.6% and 41.2%, respectively；while both of the positive predicted value were 100%. There were no significant correlation between the clinicopathologic features and the methylation rate in cancer tissues and plasma （P＞0.05）. In plasma of patients whose AFP＜400 μg/L, the positive rate of combined detection of DNA methylation of SLIT2 and DAPK was 61.1% （11/18）. Conclusions The detection rate of DNA methylation of SLIT2 and DAPK genes in plasma is higher, and there is a significant correlation between the DNA methylation in HCC tissue and plasma, based on MSP method. DNA methylation in plasma, as an non-invasive method, could be used to diagnose HCC, especially for the patients whose AFP is negative. HBV infection may be only associate with DNA methylation of part gene.
With the in-depth research on bone repair process, and the progress in bone repair materials preparation and characterization, a variety of artificial bone substitutes have been fully developed in the treatment of bone related diseases such as bone defects. However, the current various natural or synthetic biomaterials are still unable to achieve the structure and properties of natural bone. Carbon nanotubes (CNTs) have provided a new direction for the development of new materials in the field of bone repair due to their excellent structural stability, mechanical properties, and functional group modifiability. Moreover, CNTs and their composites have broad prospects in the design of bone repair materials and as drug delivery carriers. This paper describes the advantages of CNTs related to bone tissue regeneration from the aspects of morphology, chemistry, mechanics, electromagnetism, and biosafety, as well as the application of CNTs in drug delivery carriers and reinforcement components of scaffold materials. In addition, the potential problems and prospects of CNTs in bone regenerative medicine are discussed.
ObjectiveTo explore the effects of silencing the expression of ubiquitin-conjugating enzyme E2T (UBE2T) gene on proliferation, apoptosis, migration and invasion abilities of A549 cells.MethodsA549 cells were cultured in vitro. Three sets of shRNA-UBE2T plasmid vectors (UBE2T-shRNA1 group, UBE2T-shRNA2 group, UBE2T-shRNA3 group) and shRNA-NC (shRNA-NC group) were constructed, respectively. A549 cells were transfected with lipofection transfection. The cells transfected with empty vector were enrolled as control (control group). The transfection efficiency was detected by RT-PCR. The effects of silencing the expression of UBE2T gene on biological behaviors (proliferation, apoptosis, migration, and invasion) of lung cancer A549 cells were detected by clone formation assay, flow cytometry, Transwell assay and scratch test. The expression of proliferation and apoptosis related proteins, and expression of PI3K/AKT signaling pathway proteins were detected by Western blot. ResultsAfter transfection, expression level of UBE2T mRNA in UBE2T-shRNA1 group, UBE2T-shRNA2 group and UBE2T-shRNA3 group was significantly down-regulated (all P<0.05), whose down-regulation was the most significant in UBE2T-shRNA3 group (P<0.05). Compared with control group and shRNA-NC group, clone formation rate, number of invasion A549 cells, scratch healing rate, Ki67 expression, PCNA expression, p-PI3K/PI3K ratio and p-AKT/AKT ratio were significantly decreased in UBE2T-shRNA3 group (P<0.05), while A549 apoptosis rate, Bax/Bcl-2 ratio and cleaved caspase-3/caspase-3 ratio were significantly increased (P<0.05). There were no significant differences in the above indexes between control group and shRNA-NC group (P>0.05). ConclusionsThe shRNA interfering with UBE2T is reliable to construct the model of A549 cells with stable low-expression UBE2T. Down-regulation of UBE2T expression can promote apoptosis of A549 cells, inhibit their proliferation, invasion and migration abilities. The mechanism may be related to inhibiting the activation of PI3K/AKT signaling pathway.
Objective To investigate the improvement effects and mechanisms of composite chitosan (CS) hydrogel on traditional polypropylene (PP) mesh for repairing abdominal wall defects. Methods CS hydrogel was prepared via physical cross-linking and then combined with PP mesh to create a CS hydrogel/PP mesh composite. The internal structure and hydrophilicity of the composite were characterized using macroscopic observation, upright metallographic microscope, scanning electron microscopy, and water contact angle measurements. The performance of the composite (experimental group) in resisting cell adhesion and supporting cell infiltration was assessed through fibroblast (NIH-3T3) infiltration experiments and human umbilical vein endothelial cells (HUVECs) tube formation assays, and simple cells were used as control group. Finally, a bilateral abdominal wall defect model (1.5 cm×1.0 cm) was established in 18 Sprague Dawley rats aged 8-10 weeks, with the composite used on one side (experimental group) and PP mesh on the other side (control group). The effects on promoting wound healing, preventing adhesion, angiogenesis, and anti-inflammation were investigated through macroscopic observation, histological staining (HE and Masson staining), and immunohistochemical staining (CD31, CD68). Results The composite appeared as a pale yellow, transparent solid with a thickness of 2-3 mm, with the PP mesh securely encapsulated within the hydrogel. Scanning electron microscopy revealed that the hydrogel contained interconnected pores measuring 100-300 μm, forming a porous structure. Contact angle measurements indicated that CS hydrogel exhibited good hydrophilicity, while PP mesh was highly hydrophobic. In vitro cell culture experiments showed that DAPI staining indicated fewer positive cells in the experimental group after 1 day of culture, while the cells in control group covered the entire well plate. After 3 days of culture, the cells in experimental group were spherical and displayed uneven fluorescence, suggesting that the material could reduce cell adhesion while supporting cell infiltration. HUVECs tube formation experiments demonstrated an increase in cell numbers in experimental group with a trend towards tube formation, while cells in control group were sparsely distributed and showed no migration. In the rat abdominal wall defect repair experiment, results showed that after 1 week post-surgery, the experimental group had tissue and blood vessels infiltrating, and by 4 weeks, the integrity was well restored with significant regeneration of muscle and blood vessels, while the control group exhibited adhesions and incomplete healing. HE staining results indicated weaker cell infiltration in the experimental group, with cell density significantly higher than that of the control group at 2 and 4 weeks post-surgery (P<0.05). Masson staining revealed that collagen fibers in the experimental group were arranged neatly, with significantly increased collagen content at 2 weeks post-surgery (P<0.05), while collagen content was similar in both groups at 4 weeks (P>0.05). Immunohistochemical staining showed that CD31-positive cells were evenly distributed between muscle layers in the experimental group, whereas the control group exhibited notable defects. At 2 weeks after operation, the CD31-positive cell ratio was significantly higher than that in the control group (P<0.05); at 2 and 4 weeks after operation, the CD68-positive cell ratio in the experimental group was significantly lower than that in the control group (P<0.05). Conclusion CS hydrogel has a positive effect on preventing adhesions and promoting wound healing, exhibiting anti-inflammatory and pro-angiogenic properties during the healing process. This provides a promising strategy to address challenges related to abdominal adhesions and reconstruction.