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.
ObjectiveTo summarize the latest research progress of graphene and its derivatives (GDs) in bone repair. MethodsThe relevant research literature at home and abroad in recent years was extensively accessed. The properties of GDs in bone repair materials, including mechanical properties, electrical conductivity, and antibacterial properties, were systematically summarized, and the unique advantages of GDs in material preparation, functionalization, and application, as well as the contributions and challenges to bone tissue engineering, were discussed. ResultsThe application of GDs in bone repair materials has broad prospects, and the functionalization and modification technology effectively improve the osteogenic activity and material properties of GDs. GDs can induce osteogenic differentiation of stem cells through specific signaling pathways and promote osteogenic activity through immunomodulatory mechanisms. In addition, the parameters of GDs have significant effects on the cytotoxicity and degradation behavior.ConclusionGDs has great potential in the field of bone repair because of its excellent physical and chemical properties and biological properties. However, the cytotoxicity, biodegradability, and functionalization strategies of GDs still need to be further studied in order to achieve a wider application in the field of bone tissue engineering.
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 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.