Expression of sclerostin in alveolar bone remodeling of ovariectomized rats / 口腔疾病防治

Objective@# To investigate the expression and distribution of sclerostin in the alveolar bone of rat in the absence of estrogen, and to provide evidence for the analysis of the histological correlation between sclerostin and alveolar bone remodeling in rats. @*Methods @#The experimental subjects of this study were 32 8-week-old female Wistar rats. Among them, 16 rats were ovariectomized (OVX), and 16 rats were subjected to a sham operation (Sham). These rats were sacrificed 1, 2, 3, and 4 weeks after the operation, and the mandibles were removed and embedded. The mesial and distal sections of the rat,s mandibular first molars were selected and stained with anti-tartrate phosphatase (TRAP), sclerostin immunostaining, multiple immunostainings, RANKL and TRAP double staining, and silver-plated multiple staining. @*Results @#As the postoperative time in rats increased, the TRAP-positive osteoclasts counts in the OVX group in the interalveolar septum of mandibular first molar increased significantly, and statistical difference was noted between the groups (P ＜ 0.05). The OVX 2w, 3w, and 4w groups exhibited more TRAP-positive osteoclasts compared with the Sham group at the corresponding time point, and the results were statistically different (P ＜ 0.05). Sclerostin immunostaining revealed that the proportion of positive bone cells in the mesial side of the periodontal ligament area of mandibular first molar in the OVX group gradually decreased. Statistical differences were noted between the OVX 3w group and the OVX 4w group as well as the OVX 1w group and, the OVX 2w group (P ＜ 0.05). In the comparison between the area near the periodontal ligament and the central area of the alveolar bone septum of the mandibular first molar in the same group, the positive expression ratio of sclerostin in the OVX 3w and OVX 4w groups in the area near the periodontal ligament was reduced compared with that in the central area of the alveolar bone septum. The results were statistically significant (P ＜ 0.05). A larger number of osteoblasts was noted around the osteoclasts in the OVX 4w group compared with the Sham 4w group based on ALP/ TRAP /sclerostin multiple staining, whereas less sclerostin-positive osteoblasts were noted in the OVX 4w group. Sclerostin/TRAP/silver plating staining showed that the bone tubules around the sclerostin positive bone cells mostly exhibited a parallel and neat arrangement, and the bone tubules around sclerostin negative bone cells were more irregular and disorderly arranged in the OVX 4w group@*Conclusion@#Sclerostin protein is involved in alveolar bone remodeling in estrogen-deficient rats.

A Review: Mechanistic Insights Into The Effect Of Thyroid Disorders On Estrogen Level And Bone Mineral Density

Thyroid hormone serves as an indispensable component for the optimum functioning of various biological systems. They curb body’s metabolism, regulates the estrogen level, regulates bone turnover, essential for skeletal development and mineralization. Within the scope of knowledge, it is intimately familiar that thyroid disorders have widespread systemic manifestations, among which in hypothyroidism, even though elevated TSH (thyroid-stimulating hormone) may reduce estrogen level which in turn stimulates osteoclasts and thus cause osteoporosis, while hyperthyroidism accelerates bone turnover. Hypothyroidism does not directly interfere with the skeletal integrity, but treatment with levothyroxine for the suppression of TSH to bring the hypothyroid patient to euthyroid state for a long haul; lead to simultaneous reduction in bone mass and in (bone mineral density) BMD. After the initial relevation of the correlation between thyroid disorders and osteoporosis in numerous studies have emphasized that both hypo and hyperthyroidism either directly or indirectly affects the bone mineral density or leads to the progression of osteoporosis. Therefore the present study is aimed and so designed to review all the possible associations between them and the impact of thyroid disorders on estrogen level and bone mineral density. The main findings of this review indicate that both excesses as well as deficiency of thyroid hormone can be potentially deleterious for bone tissue.

Effects of Fluid Shear Stress on Gene Expression of Piezo1 in the Cells During Osteogenic Differentiation / 医用生物力学

Objective To investigate the gene expression of Piezo1 in four types of bone cells at different stages of osteogenic differentiation under fluid shear stress (FSS). Methods The mouse-derived mesenchymal stem cells (MSC), osteoblast-like cells MC3T3-E1, post-osteoblasts MLO-A5 and osteocytes MLO-Y4 were exposed to FSS at different magnitude (0.1, 1.1 Pa) with a custom-made cone-plate flow chamber for 0.5, 1, 3, 6, 12 h, respectively. The expression of Piezo1 mRNA was assessed by quantitative real-time polymerase chain reaction. Results Both Piezo1 and Piezo2 were expressed in four types of bone cells. The expression of Piezo1 was significantly up-regulated in all cells under FSS stimulation, and the expression level under 1.1 Pa FSS was significantly higher than that under 0.1 Pa FSS. In addition, the expression of Piezo1 in MSC, MC3T3-E1 and MLO-A5 cells increased to the highest level at 1 h under FSS stimulation. The expression of Piezo1 in MC3T3-E1 cells was much higher than that in the other three types of cells. Conclusions The expression of Piezo1 was related to the process of osteogenic differentiation, FSS level and loading time, and this research finding is of great significance to reveal the mechanism of mechanotransduction in bone tissues and to establish clinical treatment for bone diseases.

The role of under-investigated connexins in musculoskeletal tissue: a brief review with emphasis on bone tissue / El papel de las escasamente investigadas conexinas en el tejido músculo-esquelético: una breve revisión con énfasis en el tejido óseo

Connexins (Cxs) are a family of transmembrane proteins that form gap junctions and hemi-channels, which mediate cell-cell communication between neighboring cells and the respective extracellular milieu in different tissues. Most tissues and cell types throughout the body express one or more Cx proteins, highlighting its importance in regulating cell growth, differentiation, adhesion, migration, cell death and others. Moreover, Cx can propagate intracellular signals through its C-terminus domain, and thus function beyond a mere channel. Cx43 is the most highly expressed and most well studied Cx in bone and musculoskeletal tissues, although Cx40, Cx45, Cx46 and more recently, the Cx37 have been described in bone tissue, along with Cx26, Cx32 and Cx39 in other musculoskeletal tissues. Here, we discuss the basic structure of gap junctions and the role of the Cxs in musculoskeletal tissue, with special focus on Cx37. (AU)

Las conexinas (Cxs) son una familia de proteínas transmembrana que forman uniones en hendidura y hemicanales encargados de mediar la comunicación entre células vecinas y el respectivo medio extracelular en diferentes tejidos. La mayoría de los tejidos y células expresan una o más proteínas conexina, jugando un papel importante en la regulación de la proliferación celular, diferenciación, adhesión, migración y muerte celular, entre otras funciones. Además de actuar como un canal, las conexinas pueden propagar señales intracelulares a través del dominio C-terminal. La Cx43 es la conexina mas expresada y mejor estudiada en el tejido óseo y el músculo, aunque las Cx40, Cx45, Cx46, y mas recientemente Cx37, son también detectadas en el hueso. A su vez la expresión de la Cx26, Cx32 y Cx39 ha sido observada en otros tejidos músculoesqueléticos. En este manuscrito describimos la estructura básica de las uniones tipo gap y el papel que las Cxs, y en especial la Cx37, tienen en tejidos músculo-esqueléticos. (AU)

Potential to differentiation of human dermis-derived fibroblast-like cells into mesenchymal stem cells in vitro / 吉林大学学报(医学版)

Objective:To study the differentiation capacity of the fibroblast-like cells isolated from human skin dermis into mesenchymal stem cells, and to explore the feasibility to use these cells as alternative cell source of autologus bone marrow mesenchymal stem cells (BMSCs ) for regeneration of tissue inj uries and defects. Methods:Full thickness skin samples were obtained from the abdomen of surgical patients, then digested with dispase and collagenase Ⅰ subsequently. Thereafter, the digested cells were collected and cultured, followed by suspension with serum free medium containing N2,B27,basic fibroblast growth factor (bFGF),and epidermal growth factor (EGF).The skin dermis derived spheroids (SDDSs)were collected and monolayer cultured in serum-containing medium.Finally,the cells were characterized by immunofluorescence staining and differentiation assays.Results:The dermis derived cells proliferated and formed SDDSs in the suspension of serum-free medium. After monolayer cultivation in serum-containing medium, the cells from spheroids were successfully expanded to large number. The cells expressed mesenchymal stem cells markers CD90, CD105 and vimentin. Under osteogenic,chondrogenic and adipogenic differentiation conditions,these cells were differentiated into the alizarin red,safranin O, and oil red O staining positive cells, displayed similar differentiation traits with BMSCs. However,safranin O staining was weaker in the dermis derived cells than BMSCs. Conclusion:A kind of fibroblast-like cells exist in human skin dermis, and have osteocytic, chondrogenic and adipogenic differentiation potentials,demonstrating that these cells will be utilized as a novel cell source for repairing the tissue injury and defect in clinic.

Effects of nanoparticles to bone cells and potential applications in orthopedics / 国际生物医学工程杂志

Biomaterials are commonly applied in regenerative therapy and tissue engineering in bone.Generally,nanoparticles interact distinctively with bone cells and tissue,depending on their com-position,size,and shape.Therefore,detailed analyses of nanoparticle effects on cellular functions have been performed to select the most suitable candidates for supporting bone regeneration.This review will highlight potential nanoparticle applications in bone.We found that mesenchymal stem cells (MSCs) display exceptional regenerative potential.The delivery of genetic material with nanoparticulate carriers offers the possibility of overcoming certain disadvantages of standard protein delivery approaches.Moreover,nanoparticles are already clinically applied in cancer treatment.Thus,corresponding efforts could lead to new therapeutic strategies to improve bone regeneration or to treat bone disorders.

An overview of bone cells and their regulating factors of differentiation

Bone is a specialised connective tissue and together with cartilage forms the strong and rigid endoskeleton. These tissues serve three main functions: scaffold for muscle attachment for locomotion, protection for vital organs and soft tissues and reservoir of ions for the entire organism especially calcium and phosphate. One of the most unique and important properties of bone is its ability to constantly undergo remodelling even after growth and modelling of the skeleton have been completed. Remodelling processes enable the bone to respond and adapt to changing functional situations. Bone is composed of various types of cells and collagenous extracellular organic matrix, which is predominantly type I collagen (85-95%) called osteoid that becomes mineralised by the deposition of calcium hydroxyapatite. The noncollagenous constituents are composed of proteins and proteoglycans, which are specific to bone and the dental hard connective tissues. Maintenance of appropriate bone mass depends upon the precise balance of bone formation and bone resorption which is facilitated by the ability of osteoblastic cells to regulate the rate of both differentiation and activity of osteoclasts as well as to form new bone. An overview of genetics and molecular mechanisms that involved in the differentiation of osteoblast and osteoclast is discussed.

A HISTOCHEMICAL OBSERVATION ON ISOLATED BONE CELLS FROM CALVARIUM OF RAT EMBRYOS CULTURED IN VITRO / 解剖学报

An experimental study was carried out on the isolated bone cells, from the embryonic calvarium of Sprague-Dawley rats which were taken out in vitro culture in the later period of gestation. Observation of the early stage of culture was carried out with phase contrast microscope, H. E. staining and AcP and AlP technique. It was found that both the osteogenic cells of the cambium layer of the periosteum and the undifferentiated cells from the bone marrow could develop into large squamous-shaped cells. These cells possessed many processes connected with the adjacent cells and stained light red color with Sirius Red but revealed no birefringency under polarized microscope. This indicates that these cells are precursors of collagen formation. The negative reaction with the alkaline phosphatase staining pointed out that these cells still belong to the osteogenic cells.