OBJECTIVETo observe osteoclasts on the resorbing surface of human deciduous teeth.

METHODSAfter fixing the collected deciduous teeth, we prepared the tooth slices without decalcification, treated them with HE and TRAP dyestuff, and observed the osteoclasts under light and scanning electron microscope.

RESULTSThere were large quantity of various forms of overlapping and huge osteoclasts with many nuclei and silk-like protuberances on the resorbing surface of deciduous teeth. The multinucleated osteoclasts align on the surface of coarse dentin.

CONCLUSIONOn the resorbing surface of human deciduous teeth there are large amount of osteoclasts which can be used as a source of studying human osteoclast.

Humans ; In Vitro Techniques ; Osteoclasts ; cytology ; Tooth Resorption ; Tooth Root ; cytology ; Tooth, Deciduous ; cytology

Osteoclasts and osteoblasts are not exist alone,while communicating with each other through direct contact, diffusible paracrine factors and cell-bone matrix interaction. Co-culture system of osteoblast with osteoclast,including direct co-culture and indirect co-culture. It should be according to the ratio of osteoclasts and osteoblasts under the pathology, choosing the same species. Compared with lonely culture of osteoblasts or osteoclasts,co-culture system is much closer to the microenvironment in vivo. It benefits to explain the interactions between osteoblasts and osteoclasts, exploring molecular communication in bone diseases. It was mainly used to investigate the pharmacological mechanism of herbal and western medicine in bone remodeling. Some osteoporosis drugs (such as epimedium,sanchi, fructus psoraleae, ranelate strontium) not only promoted osteoblastic bone formation, but also inhibited osteoclastic bone resorption in the system,so as to balance bone homeostasis. At the same time,it has been used to study medical physics and assess biomedical materials in recent years. Considerably,the co-cultrue system will be used to study the subchondral bone remodeling and its pharmacological mechanism of herbal and western medicine in osteoarthritis.
Animals ; Bone Remodeling ; Cell Communication ; Coculture Techniques ; Humans ; Osteoblasts ; cytology ; Osteoclasts ; cytology

OBJECTIVETo compare between MLO-Y4 osteocyte and osteoblast to support osteoclast formation in co-culture system.

METHODSMLO-Y4 cells and murine osteoblast cells were co-cultured with bone marrow cells with or without vitamin D₃ presence.Bone marrow cells were as control group. Tartrat resistant acid phosphatase (TRAP)+ giant cells with three or more nuclei were counted and compared under a microscope at day 9.

RESULTSIn the absence of vitamin D₃, (1963.3 ± 93.1)/plate osteoclasts were observed when MLO-Y4 cells co-cultured with bone marrow cells in 24-well plate.While only (12.7 ± 5.5)/plate osteoclasts were found in the osteoblast group, and (6.0 ± 1.0)/plate in control group. The statistical difference occurs for any two groups (P < 0.05). Vitamin D₃ could significantly increase osteoclast formation in the three groups.

CONCLUSIONSOsteocytes could induce osteoclastogenesis without the presence of vitamin D₃ and vitamin D₃ could enhance the induction effects of MLO-Y4 and osteoblast cells.

Animals ; Cell Line ; Cholecalciferol ; chemistry ; Coculture Techniques ; Culture Media ; chemistry ; Mice ; Osteoblasts ; cytology ; Osteoclasts ; cytology ; Osteocytes ; cytology

BACKGROUNDBisphosphonates (BPs) have been reported to reduce local recurrence in giant cell tumor (GCT) of bone because of their osteoclast-suppressing effect; however, the optimal mode of delivery and the dose and duration of treatment of BPs remain to be established. To address these issues, it is first necessary to clarify the manner of action of BPs on osteoclasts. We herein evaluated the osteoclast-suppressing effect of sodium ibandronate in vitro.

METHODSMouse osteoclasts (OCLs) were generated in vitro using mouse bone marrow mononuclear cells. First, various concentrations of sodium ibandronate and equal amounts of phosphate-buffered saline were added to cell culture media. The number of multinucleated cells (over three nuclei) was recorded in each group, OCL formation was compared, and the most effective concentration of sodium ibandronate was determined. Then, high concentrations of sodium ibandronate were added to the experimental cell culture media; no ibandronate was given in the control group. Comparisons were made between the two groups in terms of OCL adhesion, migration, and bone resorption.

RESULTSOCL formation was suppressed by sodium ibandronate in vitro; the most pronounced effect was observed at the concentration of 10(-5) mol/L. OCL migration and bone resorption were significantly suppressed at this concentration, though there was no effect on OCL adhesion.

CONCLUSIONSSodium ibandronate was effective in suppressing OCLs and decreasing resorption in GCT. The strong anti-OCL effectiveness at a high concentration in vitro indicates a topical mode of application.

Animals ; Bone Resorption ; Cell Movement ; drug effects ; Cells, Cultured ; Diphosphonates ; pharmacology ; Mice ; Osteoclasts ; cytology ; drug effects

On the basis of the well-established principles and techniques about flow chamber, we have designed and made a kind of parallel plate system to apply steady fluid shear stress to osteoclast-like cells etc. in vitro. Biocompatible rubber and metal clamping apparatus made of aluminium alloy are used to seal the flow chamber without changing its even height designed beforehand. The influence of hydrostatic pressure on cells is minimized by adjusting the glass slide and the fluid surface in the upper reservoir to the same horizontal plane. This system can be used to investigate the responses of osteoclast-like cells etc. to fluid shear force in terms of morphology, physiology or biochemistry.
Biomechanical Phenomena ; Cell Culture Techniques ; instrumentation ; Humans ; Osteoclasts ; cytology ; Pulsatile Flow ; Stress, Mechanical

OBJECTIVETo study the role of osteocyte in bone remodeling due to mechanical loading in vitro.

METHODSMLO-Y4 osteocyte-like cells were exposed to fluid flow-induced shear stress(12dyn/cm(2))for 0, 1, 2, 4, 6, 12, and 24 hours. Osteocyte exposed to shear stress at different time points were used in co-culture system for 9 days, and then the cells were stained with tartrate-resistant acid phosphatase on the 9(th) day and the amount of positively stained osteoclasts were counted and compared. The expressions of osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa (RANKL) were detected by semi-quantitative reverse transcription polymerase chain reaction (semi-quantitative RT-PCR).

RESULTSCompared with bone cells without stimulation with fluid flow-induced shear stress, the amount of osteocytes significantly decreased at all time points after the application of fluid flow-induced shear stress (all P<0.05). The OPG expression at mRNA levels was significantly up-regulated in the first 12 hours (P<0.001), the RANKL mRNA expression was significantly down-regulated in the first 4 hours (P<0.05), and the RANKL/OPG ratio significantly decreased within 12 hours (P<0.01). However, all these indicators showed no significant difference at 24 hours when compared with the pre-stimulation level.

CONCLUSIONOsteocytes may act as mechanosensors that are able to inhibit bone resorption after mechanical loading; however, such effect shows certain adaptation ability to shear stress as time goes.

Animals ; Cell Differentiation ; Cells, Cultured ; Coculture Techniques ; Male ; Mice ; Osteoclasts ; cytology ; Osteocytes ; cytology ; Osteoprotegerin ; metabolism ; RANK Ligand ; metabolism ; Stress, Mechanical

Bidirectional Eph-Ephrin signaling as a focal point of research in cell-cell communications is critical for generation of nerves and vesssels as well as invation and metastasis of tumor cells. The roles for Ephrin-Eph bidirectional signaling in bone remodeling were important. EphrinB2 is expressed on osteoblasts and EphB4 is expressed on osteoclasts. Forward signaling through the EphB4 receptor into mesenchymal precursors promotes osteoblast differentiation, while reverse signaling through the EphrinB2 ligand into osteoclast suppresses differentiation. Signaling between the ligand EphrinB2 and the receptors EphB4 explains bidirectional signaling between osteoblasts and osteoclasts,bone absorption and remodeling, which may lay a theoretical foundation for identifying drug targeting and preventing and treating bone loss.
Animals ; Bone Remodeling ; physiology ; Ephrin-B2 ; physiology ; Humans ; Osteoblasts ; cytology ; Osteoclasts ; cytology ; Receptor, EphB4 ; physiology ; Signal Transduction ; physiology

Our previous studies on the function of the osteoblasts (OBs) have shown that worn titanium particles decrease osteoblast function and promot secretion of bone resorption cytokines of OBs surrounding the synovium-like interface membrane of loosening implants. The current study was aimed to test the hypothesis that osteoclasts (OCs) bone absorption function is induced by conditioned media (CM) prepared from OBs loaded in the presence or absence of titanium particles (with three mean diameters 6.9 microm, 2.7 microm, and 0.9 microm, respectively). The effects of CM on OCs function were examined using a combination of the morphological characteristics tests, i.e., TRAP dyeing, scanning electron microscopy, F-actin immunofluorescence protocol for confocal microscopy, bone resorption lacunae assay, osteoclastic calcium tracking, with biochemical evaluation, i.e., C-terminal cross-linked telopeptides of type I collagen evaluated with ABC-ELISA method. The results showed that CM from 0.9 microm titanium particles could induce osteoclastic differentiation and formation, could partially influence the survival of the OCs; while CM of 2.7 microm and 6.9 microm titanium particles, especially the latter, could obviously augmented osteoclastic activity, survival, or differentiation. The stimulation of osteoclast function may be due to a parallel increase in the intracellular free calcium concentration. The present study provides strong support for the hypothesis that osteoclastic activity, survival, or differentiation are very important in the development of aseptic loosening. The development of therapeutic interventions to reduce osteoclastic function and optimization of biomaterials may be useful approaches for improving the performance of orthopaedic implants.
Animals ; Bone Resorption ; Cells, Cultured ; Osteoblasts ; cytology ; physiology ; Osteoclasts ; cytology ; physiology ; Particle Size ; Prosthesis Failure ; Rabbits ; Titanium ; pharmacology

Searched the articles between 2000 and 2010, found out and summarized the articles with the topic on the experiment and new techniques of traditional Chinese medicine treating to osteoporosis. The preventive and therapeutic effect to osteoporosis by traditional Chinese medicine had been developed in the past 10 years. The study on standardization of experimental drugs, and the mechanism study with modern cell culture techniques should be enhanced.
Animals ; Humans ; Medicine, Chinese Traditional ; Osteoblasts ; cytology ; drug effects ; Osteoclasts ; cytology ; drug effects ; Osteoporosis ; drug therapy ; Tissue Engineering

OBJECTIVETo investigate the osteoblast-like functional characteristics exhibited by human periodontal ligament cells (hPDLCs) under mechanical force.

METHODSHuman PDLCs cultured in vitro were stretched by mechanical force. Radioimmunoassay (RIA) was used to measure the expression of secreting alkaline phosphotase (ALP) and osteocalcin (OCN). The non-secreting ALP, OCN and osteopontin (OPN) in cells were determined by immunohistochemistry.

RESULTSIt exhibited increasing of ALP secreted into conditional media, and in the 24 hour period there were two peaks which appeared at the 2nd and 4th hour and the 24th hour (P < 0.01). While in the late of the 24 hours, expression of OCN in conditional media increased (P < 0.05).

CONCLUSIONMechanical force induces hPDLCs to differentiate into functional osteoblast-like cells and plays a role in bone remodeling.

Alkaline Phosphatase ; metabolism ; Cells, Cultured ; Humans ; Osteocalcin ; analysis ; Osteoclasts ; physiology ; Osteopontin ; Periodontal Ligament ; cytology ; Sialoglycoproteins ; analysis ; Stress, Mechanical