Research on the subchondral bone architecture and bone remodeling related genes change in the initial stage of osteoarthritis in rat / 重庆医学

Objective To investigate the changes of microarchitecture and gene expression of subchondral bone in the initial stage of traumatic arthritis ,to explore the characteristics of subchondral bone remodeling and its role in the articular cartilage de‐generation .Methods The medial meniscal tear (MMT) was performed on the right knees of 13 SD rats to simulate the traumatic osteoarthritis ,while sham operation on the control group .Three weeks later ,all the rats were executed and dissected ,with proximal tibiae being kept and distributed into the two groups ,10 respectively .Micro‐computed tomography (micro‐CT) was adopted to re‐construct and analyze the subchondral bone .After being fixed by 4% paraformaldehyde ,all the samples were decalcified until six weeks passed ,followed by paraffin‐sectioning ,safranin O and fast green staining ,and examining and photographing under an ordina‐ry optical microscope .The RNA of another 3 SD rats′subchondral bone was extracted ,and a real‐time PCR test was carried out to illuminate the expression variation of bone‐formation marker genes (ALP ,RUNX2 ,and OCN) ,and bone‐resorption marker genes (TRAP ,CTSK and MMP9) ,between the two groups .Results Three weeks after MMT surgery ,subchondral bone disorders were observed among the experimental samples through micro‐CT scanning .There was lesser BV/TV ,Conn .D and Tb .Th(P<0 .05) and more Tb .Sp(P<0 .05) in the experimental group compared with the control group .In the pathological section ,arthritic degen‐eration was not spotted in both groups ,but trabeculae of the experimental group were found to be sparse .Compared with control group ,the level of mRNA expression of the bone‐formation marker genes of the experimental group was decreased(P<0 .05) ,while bone‐resorption related genes increased(P<0 .05) .Conclusion The model of initial traumatic osteoarthritis induced by MMT in rats′knees showed an active bone remodeling ,more bone absorbing than bone formation ,lowered bone volume ,and microarchitec‐ture changing of the subchondral bone .

Expression of CXCR4 and CXCR7 receptors in bone marrow mesenchymal stem cells and role of these receptors in bone repair / 中华创伤杂志

Objective To investigate the function of CXCR4 and CXCR7 receptors expressed in bone marrow mesenchymal stem cells (BMSCs) membrane surface in process of cell migration,in order to provide a theoretical basis for bone trauma repair.Methods C57BL/6 mice were selected to collect BMSCs of second passage after using the adherence culture method.Expressions of CXCR4 and CXCR7 receptors on BMSCs membrane surface were detected using immunofluorescent staining and flow cytometry.In CXCL12-induced chemotaxis of BMSCs,the assay was divided into control group (cells were seeded in serum-free medium),CXCL12 group and (cells were seeded in serum-free medium containing CXCL12),and CXCR4-blocked group (cells were seeded in serum-free medium containing CXCL12 after the blockade of CXCR4).Migration of BMSCs was qualified and used to determine the chemotaxis role of CXCR4 and CXCR7.After the blockade of CXCR4,expression of CXCR7 was detected using the Western blot method.Results lmmunofluorescence showed overexpressions of CXCR4 and CXCR7 receptors on BMSCs membrane surface.Flow cytometry showed the positive rate of CXCR4 and CXCR7 on BMSCs membrane surface was 96.4％ and 97.3％ respectively.Cell migration assay showed amount of MBSCs migration was the highest in CXCL12 group,relative higher in CXCR4-blocked group and the lowest in control group (P ＜ 0.01).In CXCR4-blocked group,expression of CXCR7 increased.Conclusion CXCR4 and CXCR7 Receptors are expressed in BMSCs membrane surface,but CXCR4 play the major role in CXCL12-induced BMSCs migration to traumatic bone wounds.

Comparative study of root canal morphology of mandibular first premolar by micro-CT and radio visio graphy / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the consistency of root canal configuration types of mandibular first premolar by using micro-CT and radio visio graphy (RVG).</p><p><b>METHODS</b>One hundred extracted mandibular first premolars with complete dental root and apex which received no endodontic treatment were randomly selected. Each tooth was radiographed with RVG through a buccolingual and mesiodistal direction, and then scanned with micro-CT and reconstructed. The classifications of the root canal types according to Vertucci's type with the two methods were compared.</p><p><b>RESULTS</b>The canal patterns were classified as type I (67%), type III (3%), type V (18%), type VII (2%), additional type (10%) with micro-CT and canal patterns as type I (71%), type III (2%), type V (23%), type VII (1%), additional type (3%) with RVG. 63% of teeth showed one canal in both micro-CT and RVG. Only 25% of teeth were diagnosed as complex canal by the same canal type in both micro-CT and RVG. The Kappa value between micro-CT and RVG was 0.541 which suggested that the two kinds of methods had intermediate consistency. 82.8% of the premolars with root groove had two or more than two canals.</p><p><b>CONCLUSION</b>Although RVG can basically reflect the root canal system type of the mandibular first premolars in vitro, it offers poor accuracy images to complex root canals. Micro-CT three-dimensional images could clearly and precisely display the root canal system morphology of the mandibular first pre-molars in vitro.</p>

The observation of surface morphology of enamal and temperature of dental pulp cavity in vitro after irradiated by Er:YAG laser / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the changes of surface morphology and temperature of dental pulp cavity in vitro after irradiated by Er:YAG laser with different energy and irradiation time.</p><p><b>METHODS</b>All of the 96 samples from 24 teeth in vitro were collected from dental clinical departments then divided into two groups (group A and group B) randomly. We chose the energy of 20 Hz, and 1, 2, 3, 4, 5, 6 W to treat the samples in group A and group B and the irradiation time was 10s or 20s. We recorded the temperature changes of dental pulp cavity by digital thermometer and observe the morphology of tooth enamel by scanning electron microscope (SEM).</p><p><b>RESULTS</b>With the extension of irradiation time and increasing of energy, the temperatures of dental pulp cavity were significantly increased after the treatment of Er: YAG laser. The two groups of tooth enamel surface morphology were changed after irradiated by Er: YAG laser with different energy and irradiation time. However, there was no melting and carbonation on the surface of tooth enamel after the treatment of Er:YAG laser in two groups.</p><p><b>CONCLUSION</b>The temperatures of dental pulp cavity were increased after irradiated by increasing laser energy density fom 1 W to 6 W. No melting or carbonized phenomenon was found in enamel within the energy of 1 W to 6 W. All the data would provide evidences for clinical treatment of cavity.</p>

The effect of leukemia inhibitory factor on the proliferation and differentiation of ectomesenchymal cells of mandibular process in Balb/c fetal mice / 实用口腔医学杂志

Objective: To investigate the effect of leukemia inhibitory factor (LIF) on the of proliferation and differentiation of ectomesenchymal cells of mandibular process in Balb/c fetal mice . Methods: Ectomesenchymal cells from the E12.5 mice mandibular process were cultured in DMEM/F12 with 10 6u/L LIF (experimental group) or without LIF (control). The proliferation effect was detected by MTT assay, Brdu test and flow cytometry. Immunohistochemistry were used to identify the differentiation state. Results: By day 7 the A value of the experimental group was 0.38?0.03,that of the control 0.30?0.02 (P

Tissue engineering of dentin-pulp complex-like structures by rat first branchial arch cells / 第三军医大学学报

Objective To evaluate the odontogenetic ability of first branchial arch cells of E12.5 rats. Methods First branchial arch cells (mandibular process) of E12.5 SD rats were isolated enzymatically and collected. After combined with gelatin sponge, the cells were transplanted into the renal capsule of a rat. The specimen was taken out and evaluated by histological and immunohistochemical methods in 4 weeks after growth in renal capsule. Results The first branchial arch cells with gelatin sponge developed dentin-pulp complex-like structure. Dentin sialoprotein (DSP) was expressed in the newly formed dentin-like structure. The green mineralized matrix was further identified with Masson’s trichrome staining. Conclusion Cells from first branchial arch of E12.5 rats can partially keep genetic signal of tooth growth and form dentin-pulp complex-like structure in renal capsule.