BACKGROUND:Cytoskeleton plays an important role in the transduction of mechanical signal, and intermittent tensile stress can promote osteogenic differentiation. However, there is no relevant study about the change of cytoskeleton in osteoporosis rat bone marrow mesenchymal stem cells under intermittent tensile stress. OBJECTIVE:To investigate the effects of intermittent tensile stress on the cytoskeleton of osteoporosis rat bone marrow mesenchymal stem cells during osteogenic differentiation. METHODS:Bone marrow mesenchymal stem cells were obtained from osteoporosis rats and cultured in vitro. The 5%, 10%and 15%tensile stress were strained on the bone marrow mesenchymal stem cells through FX-4000T Flexcell. No stress was in the control group. Osteogenic differentiation of bone marrow mesenchymal stem cells was observed through alkaline phosphatase staining, while the change of cytoskeleton was observed by confocal laser scanning microscopy with figures col ected for analysis by Image-ProPlus 6.0 software. The area of cells, ratio of length to width and integrated fluorescence intensity of cytoskeleton protein F-actin were measured. RESULTS AND CONCLUSION:Under tensile stress, bone marrow mesenchymal stem cells from osteoporosis rats arranged in the direction vertical to mechanical stimulation. cells under different tensile stress differentiated towards osteoblasts. The result of alkaline phosphatase staining showed the most significant difference in 10%group, and quite an amount of cells lining lost succession in the 15%group. Under stress, the F-actin filaments were rearranged in paral el accordingly, which showed a reconstruction of cytoskeleton. Imaging analysis indicated that the area of bone marrow mesenchymal stem cells was decreased in 10%and 15%groups (P<0.05) with the increased ratio of length to width (P<0.05), and expression of F-actin increased in5%, 10%, 15%groups (P<0.05) after tensile stress. Under mechanical stimulation, the cytoskeleton of bone marrow mesenchymal stem cells from osteoporosis rats is shown to have corresponding alterations during osteogenic differentiation.

BACKGROUND:Adenovirus, expressing within a limited period, can limit the expression time and amount of target genes that is not conducive to ongoing experiments. Here, we select adenovirus as vectors for genetic recombination with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (Trail) gene fragment.
OBJECTIVE:To explore the construction of recombinant lentiviral vector carrying Trail in rats
METHODS:The Trail gene was obtained:according to GenBank in rat Trail gene sequence (NM_145681.1), we designed the gene specific primers of Trail-Age I-F and Trail-AgeI-R, and used AgeI as enzyme cutting site. PCR was applied to amplify Trail gene from rat cDNA Library and construct recombinant plasmids after cutting Trail gene to be cloned into expression vector GV218 by AgeI. Recombinant plasmids were transfected into 293T cells by Lipofeetamine2000 encapsulated recombinant plasmid and auxiliary packaging carrier. The Trail protein of lentiviral plasmids was expressed. Fol owing virus col ection, we identified virus titer and extracted protein from cells to detect Trail expression by western blot assay.
RESULTS AND CONCLUSION:Screened positive Escherichia coli DH5a competent cells were sequenced with 861 bp, which was consistent with Trail nucleotide sequence in GenBank. After transfection 2 days, virus liquid was col ected and confirmed as recombinant plasmid including Trail gene by PCR and Trail proteins expressed in 293T cells by western blot assay. Hole dilution method and real-time fluorescent quantitative PCR determination showed that the virus titer was 2×109 TU/mL. In this study, recombinant lentiviral vector carrying Trail is successful y constructed by homologous recombination in Escherichia coli.

Orthodontic treatment is more complicated when both soft and hard tissues must be considered because an impacted maxillary canine has important effects on function and esthetics. Compared with extraction of impacted maxillary canines, exposure followed by orthodontic traction can improve esthetics and better protect the patient's teeth and alveolar bone. Therefore, in order to achieve desirable tooth movement with minimal unexpected complications, a precise diagnosis is indispensable to establish an effective and efficient force system. In this report, we describe the case of a 31-year-old patient who had a labio-palatal horizontally impacted maxillary left canine with a severe occlusal alveolar bone defect and a missing maxillary left first premolar. Herein, with the aid of three-dimensional imaging, sequential traction was performed with a three-directional force device that finally achieved acceptable occlusion by bringing the horizontally impacted maxillary left canine into alignment. The maxillary left canine had normal gingival contours and was surrounded by a substantial amount of regenerated alveolar bone. The 1-year follow-up stability assessment demonstrated that the esthetic and functional outcomes were successful.

Cells are exposed to mechanical stress, such as fluid shear stress (FSS), mechanical strain, hydrostatic pressure in vivo. FSS is considered to be the most important stress during bone homeostasis and remodeling. At present, most studies are mainly about the FSS effect on osteocytes and osteoblasts. However, the effects of FSS on bone mesenchymal stem cell (BMSCs) are not fully understood. BMSCs are of great significance in bone reconstruction and clinical treatment, so researchers increasingly focus on the response of BMSCs to FSS. The response of BMSCs to FSS depends on the alteration of cytoskeleton, matrix stiffness and elasticity, osteogenic signaling pathways and so on. In this review paper, the recent researches about the mechanotransduction mechanism of FSS, and its effect on differentiation and function of BMSCs are summarized, so as to provide new insights for studying construction of tissue engineered bone and treatment of bone diseases.

Vibration represents a micro reciprocating motion of a particle or object along a line or arc relative to a reference position, while the effect of low-magnitude high-frequency vibration (LMHFV) on skeletal system cells is similar to the mechanical stimulation of muscle movement. Bone mesenchymal stem cells (BMSCs), which have been identified as force-sensitive cells, exist in the bone marrows and have the potential of multi-lineage differentiation. Their biological characteristics can change functionally according to the appropriate stimulation in vitro, in order to reach the optimal demand of the stimulation. LMHFV can promote the osteogenic differentiation of BMSCs, therefore, the research on its mechanism can contribute to the application of vibration in the treatment of diseases such as osteoporosis, fracture, osteogenesis imperfecta, obesity as well as the promotion of orthodontic tooth movement. This paper summarizes the recent progress about the effects of vibration on BMSCs stem cells in osteogenesis and the possible mechanisms, so as to provide research ideas and methods for studying the mechanical as well as biological changes of BMSCs under vibration stimulation.

Objective:To explore the application effect of disease-oriented digitalized teaching model in the undergraduate teaching of stomatology.Methods:A total of 34 undergraduate students in clinical medicine from Batch 2018 were selected as the control group 1, 24 undergraduate students in stomatology from Batch 2015 were selected as the control group 2, and 23 undergraduate students in stomatology from Batch 2018 were collected as the experimental group. The two control groups all accepted the traditional teaching mode, and the experimental group accepted the disease-oriented digitalized teaching model. Finally, the teaching effect was evaluated through questionnaire surveys and less difficult oral professional tests. The SPSS 24.0 was used to conduct t test. Results:After accepting this teaching model, students improved their understanding of the concept of "organism" and "disease" ( P<0.05), and they had a positive evaluation of this teaching model. It was found that the tests scores of the experimental group (42.17±1.21) were significantly higher than those of non-dental major students of the same Batch (24.71±1.42) ( P<0.05), with significant differences, while without significant difference between the tests scores of the senior stemmatological students (43.33±1.30) ( P>0.05). Conclusion:This teaching model enables students to establish the concept of "organism" and form a disease-oriented knowledge framework before entering the decentralized professional courses, which may further stimulates the interest of junior students in their majors, and enhances their professional awareness compared with traditional teaching model. It's also a useful exploration for teaching hospitals to conduct teaching activities of junior undergraduates outside the classroom.

Extracellular matrix is the main element to provide mechanical clues for cells. The response of stem cells to mechanical signals is mainly achieved through the cytoskeleton. After mechanical signal is transmitted, cytoskeleton can form contractile microfilaments that actively generate tension through reorganization induced by microenvironment changes. The mechanical signals can regulate gene expression through either coupling with the nuclear skeleton directly or being transformed by the second message. Recent studies have proven that cytoskeleton tension has a series of impact on lineage specification, proliferation, differentiation and apoptosis of bone mesenchymal stem cells (BMSCs). BMSCs are of great significance in bone reconstruction and clinical treatment. The possible mechanisms about mechanotransduction and its effects of cytoskeleton tension on osteogenesis of BMSCs after micro-environmental changes were summarized.

Bone homeostasis is a relative balance between bone formation and resorption. Signal transducer and activator of transcription 3 (STAT3), which is closely related to bone homeostasis, takes part in multiple intracellular and extracellular signal pathways. STAT3 participates in the process of osteoblast differentiation regulated by several factors. It can also maintain bone homeostasis by regulating the recruitment, differentiation and activation of osteoclasts. In addition, STAT3 is involved in the interaction between osteoblasts and osteoclasts. Patients with STAT3 mutations can have several inherited bone metabolism diseases. Furthermore, STAT3 plays a critical role in load-driven bone remodeling. Mechanical stimulation promotes osteoblast differentiation and bone formation through activating or enhancing STAT3 expression during bone remodeling process. This review summarizes the participation of STAT3 in maintaining bone homeostasis together with its possible mechanisms and discusses the connection between STAT3 and mechanical stimulation in bone remodeling, so as to provide a potential pharmacological target for the treatment of bone diseases.

External apical root resorption is among the most common risks of orthodontic treatment, and it cannot be completely avoided and predicted. Risk factors causing orthodontic root resorption can generally be divided into patient- and treatment-related factors. Root resorption that occurs during orthodontic treatment is usually detected by radiographical examination. Mild or moderate root absorption usually does no obvious harm, but close attention is required. When severe root resorption occurs, it is generally recommended to suspend the treatment for 3 months for the cementum to be restored. To unify the risk factors of orthodontic root resorption and its clinical suggestions, we summarized the theoretical knowledge and clinical experience of more than 20 authoritative experts in orthodontics and related fields in China. After discussion and summarization, this consensus was made to provide reference for orthodontic clinical practice.
Humans ; Tooth Movement Techniques/adverse effects* ; Root Resorption/etiology* ; Consensus ; Dental Cementum ; Risk Factors