Clinically, there has been so far no effective way to repair the bone-missing of large extent due to gash, infection and removal of tumor. The solution of this problem can be assisted by the addition of bioactive substances to substrate materials, because the growth of peripheral tissue and the fiber tissue growing the materials can be induced to the direction of bone-tissue by these biomaterials with bioactive peptides. The peptide Arg-Gly-Asp is the point between the integrin which comes from membrane and the ligand. In certain cases, the artificially synthesized RGD can be competitively combined with the integrin on cell surface, and outer-cell information is transmitted into cells, which will cause a series of physiological changes in cells. Presently, it is reported that the RGD has the ability to induce the growth of osteoblasts, restrain the adhesion between osteoclasts and substrates. This paper reviews and introduces the progress made with the work of RGD-inducing bone regeneration.
Biocompatible Materials ; Bone Regeneration ; drug effects ; physiology ; Cell Adhesion ; drug effects ; Oligopeptides ; administration & dosage ; chemistry ; pharmacology ; Osteoblasts ; drug effects ; physiology ; Osteoclasts ; drug effects ; physiology ; Tissue Engineering ; methods

Melanocortin is the downstream mediator of leptin signaling and absence of leptin signaling in ob/ob and db/db mice revealed the enhancement of bone formation through the central regulation. While alpha-melanocyte-stimulating hormone (alpha MSH) inhibits the secretion of interleukin-1 alpha and tumor necrosis factor-alpha from the inflammatory cells, alpha MSH can also enhance clonal expansion of pro B cells linked to stimulation of osteoclastogenesis. Therefore, we tested the effect of melanocortin on bones. alpha MSH analogues [6His] alpha MSH-ND and [6Asn] alpha MSH-ND were synthesized and the radio-ligand receptor binding- and cyclic AMP generating activity were analyzed in China Hamster Ovary cell line over- expressing melanocortin receptors. The EC50 of [6His] alpha MSH-ND measured from melanocortin-1, 3, 4 and 5 receptors were 0.008 0.0045, 1.523 0.707, 0.780 0.405, and 250.320 42.234 nM, respectively, and the EC50 of [6Asn] alpha MSH-ND were 16.8 6.94, 271.8 21.95, 8.0 1.21, and 1132.5 635.46 nM, respectively. Four weeks after the subcutaneous injection of the analogues, the body weights in the [6His] alpha MSH-ND and the [6Asn] alpha MSH-ND treated groups (346.0 20.63 g vs. 350.0 13.57 g) were lower than that of the vehicle treated group (375.8 17.31 g, p 0.05). There was no difference in the total femoral BMD measured by dual x-ray absorptiometry among the three groups. Among the three groups, there were no differences in the total numbers of crystal violet positive- or alkaline phosphatase positive colonies, in the expression of Receptor Activator of Nuclear Factor Kappa-B ligand on the tibia and the total number of multinucleated osteoclast-like cells differentiated from primary cultured bone marrow cells. From the above results, no evidence of bone gain or loss was found after treatment of the alpha MSH analogues peripherally.
Animal ; Body Weight/drug effects ; Bone and Bones/*drug effects ; CHO Cells ; Cyclic AMP/biosynthesis ; Eating/drug effects ; Hamsters ; Male ; Osteoblasts/drug effects/physiology ; Osteoclasts/drug effects/physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Corticotropin/physiology ; alpha-MSH/analogs & derivatives/*pharmacology

BACKGROUNDNeurofibromatosis type 1 (NF1) is the most common genetic syndrome predisposing patients to various tumors due to dysregulation of the Ras signaling pathway. Recent research has shown NF1 patients also suffer a spectrum of bone pathologies. The pathogenesis of NF1 bone diseases is largely unknown. There is no current treatment. By Nf1 heterozygote (Nf1+/-) mice and Nf1 conditional knockout mice, we and other groups demonstrated abnormal osteoblast and osteoclast function due to dysregulation of Ras signaling. However, the specific downstream effector pathways linked to NF1 abnormal osteoblastogenesis and osteoclastogenesis have not been defined. In this study, we investigated the Ras downstream effector related with NF1 bone disease.

METHODSWe used Nf1+/+ and Nf1+/- mice as normal and NF1 models. Bone stromal cells extracted from Nf1+/+ and Nf1+/- mice were induced osteoclasts. The osteoclast cell was stained by tartrate resistant acid phosphatase staining. The osteoclast cell number was counted and the surface area of osteoclast cells was calculated under the microscope. The mRNA of mammalian target of rapamycin (mTOR) was determined by quantitative reverse-transcription-polymerase chain reaction. The presence of ribosomal protein S6 kinase was determined by Western blotting.

RESULTSCompared with Nf1+/+ mice, Nf1+/- mice had about 20% more of osteoclast cells. These osteoclast cells were larger in size with more nuclei. Hyperactive mTOR was detected in Nf1+/- osteoclast cells. Inhibition of mTOR signaling by rapamycin in Nf1+/- osteoclasts abrogated abnormalities in cellular size and number.

CONCLUSIONmTOR pathway inhibition may represent a viable therapy for NF1 bone diseases.

Animals ; Male ; Mice ; Neurofibromatosis 1 ; drug therapy ; Osteoclasts ; drug effects ; physiology ; Osteogenesis ; drug effects ; Sirolimus ; pharmacology ; TOR Serine-Threonine Kinases ; antagonists & inhibitors ; physiology

The OPG/RANKL/RANK system plays an important role in osteoclastogenesis and represents a great progress in bone biology. RANKL, which expresses on the surface of osteoblast/stromal cells and activated T cells, binds to RANK on the osteoclastic precursors or mature osteoclasts, and promotes osteoclastogenesis and bone resorption. While osteoprotegerin (OPG), which is expressed by osteoblasts/stromal cells, strongly inhibits bone resorption by binding to its ligand RANKL and thereby blocks the interaction between BANKL and RANK. A number of cytokines and hormones exert their effects on bone metabolism by regulating the OPG/RANKL ratio in the bone marrow microenvironment. RANK is also expressed on mammary epithelial cells and RANKL expression in these cells is induced by pregnancy hormones, RANKL and RANK are essential for the formation of the lactating mammary gland and the transmission of maternal calcium to neonates in mammalian species. Modulation of these systems provides a unique opportunity to develop novel therapeutics to inhibit bone loss in osteoporosis, rheumatoid arthritis, and bone metastasis of cancer. Further research should be focused on the cooperation of OPG/RANKL/RANK system with other signal pathways and the interactions among bone remodeling, immune system and endocrinology system. Currently, the development of OPG analogues or compounds which may stimulate OPG expression is becoming an attractive industry which may be profitable to both patients and manufacturers.
Animals ; Bone Resorption ; immunology ; metabolism ; Humans ; Osteoclasts ; cytology ; metabolism ; pathology ; Osteogenesis ; drug effects ; genetics ; immunology ; Osteoprotegerin ; metabolism ; physiology ; RANK Ligand ; metabolism ; physiology ; Receptor Activator of Nuclear Factor-kappa B ; metabolism ; pharmacology ; physiology ; T-Lymphocytes ; drug effects ; immunology

This study was designed to investigate the effects of some Traditional Chinese Medicine (TCM) agents on bone resorption and morphometric features of osteoclasts as well as their relationships. TCM ShengGuZaiZaoSan and XianLingGuBao, were used to treat the experimental fracture. Thirty 6-month-old Chinchilla rabbits were used for the establishment of animal models each with a 3 mm bone defect in the middle of left radius as well as of right radius. These models were divided randomly into 3 groups : ShengGuZaiZaoSan Group (Group A), XianLingGuBao groups (Group B) and control-group (Group C). Every group was further divided into 2 subgroups: a former sacrificed group (14 days after operation) and a latter sacrificed group (31 days after operation). After the rabbits being killed, the samples of their undecalcified calli were subjected to the morphometry study of bone resorption and osteoclasts. Group A had more bone resorption, compared with Group B and C. Both Groups A and B exhibited some changed morphometric features of osteoclasts as compared with Group C (P < 0.05). Simple correlation analysis indicated that bone resorption is mainly correlated with osteoclast numbers, and that in individual group, bone resorption is correlated with osteoclast form factor, area and mean photodensity (P < 0.05). These allow us to conclude that ShengGuZaiZaoSan can increase bone resorption and accelerate bone remodeling by increasing osteoclast numbers at the former stage and can enhance osteoclast function at the latter stage. These changes are beneficial to fracture healing.
Animals ; Bone Remodeling ; drug effects ; Bone Resorption ; physiopathology ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Female ; Fracture Healing ; drug effects ; physiology ; Male ; Osteoclasts ; drug effects ; pathology ; Phytotherapy ; Rabbits ; Radius Fractures ; drug therapy ; pathology ; physiopathology ; Random Allocation

OBJECTIVETo evaluate the influence of naringin on PMMA-induced osteoclastic bone resorption using the mouse air sacs model.

METHODSTotal 48 female Balb/c mices with the age of 8 to 10 weeks were chosen in the study. Air were injected into the back in 32 mices and formed the air sacs, 6 d later, the skulls (originated from other 16 mices) were implanted to the air sacs. Thirty-two animals were divided into naringin treatment group (with 2 concentrations of 150 mg/kg and 30 mg/ kg) , DMSO group and PBS blank group, 8 animals in each group. Polymethylmethacrylate (PMMA) particles were injected into the air sacs in naringin treatment groups and DMSO group so as to irritate inflammatory reaction. Naringin with 2 concentrations of 150 mg/kg and 30 mg/kg were dissolved in DMSO of 0.2 ml, and were injected into air sacs, respectively. In PBS black group, no stimulation with PMMA particles, only injected PBS, and in DMSO group, injected DMSO without naringin. Tartrate resistant acid phosphatase (TRAP), Ca2+ release, modified Masson stain and histological analysis were performed on the 7th day after stimulation.

RESULTSCompared with DMSO group, naringin treatment group's cellular infiltration decreased (P < 0.01); concentration of 150 mg/kg was better than that of concentrations of 30 mg/kg (8.90 ± 1.75 vs 15.23 ± 1.86). Naringin can decrease calcium release in the lavage of the air sacs bone resorption model, especially obvious in naringin with concentration of 150 mg/kg. Naringin can ameliorate the inflammatory reaction and the subsequent bone resorption (including bone collagen loss, TRAP positive cells amount and so on) in air sacs with bone implant and PMMA particles. Naringin with concentration of 150 mg/kg appeared to be an optimal dosage to deliver the therapeutic effects.

CONCLUSIONNaringin inhibits PMMA-induced osteoclastogenesis and ameliorates the PMMA-associated inflammatory reaction and the subsequent bone resorption.

Animals ; Disease Models, Animal ; Female ; Flavanones ; therapeutic use ; Mice ; Mice, Inbred BALB C ; Osteoclasts ; drug effects ; physiology ; Osteolysis ; chemically induced ; prevention & control ; Polymethyl Methacrylate ; toxicity

Platinum nanoparticles (PtNP) exhibit remarkable antioxidant activity. There is growing evidence concerning a positive relationship between oxidative stress and bone loss, suggesting that PtNP could protect against bone loss by modulating oxidative stress. Intragastric administration of PtNP reduced ovariectomy (OVX)-induced bone loss with a decreased level of activity and number of osteoclast (OC) in vivo. PtNP inhibited OC formation by impairing the receptor activator of nuclear factor-kappaB ligand (RANKL) signaling. This impairment was due to a decreased activation of nuclear factor-kappaB and a reduced level of nuclear factor in activated T-cells, cytoplasmic 1 (NFAT2). PtNP lowered RANKL-induced long lasting reactive oxygen species as well as intracellular concentrations of Ca2+ oscillation. Our data clearly highlight the potential of PtNP for the amelioration of bone loss after estrogen deficiency by attenuated OC formation.
Animals ; Metal Nanoparticles/*administration & dosage ; Mice ; Mice, Inbred C57BL ; NFATC Transcription Factors/metabolism ; *Osteoclasts/drug effects/physiology ; Osteoporosis/drug therapy ; Ovariectomy/adverse effects ; Oxidative Stress/drug effects ; Platinum/*administration & dosage ; *RANK Ligand/genetics/metabolism ; Reactive Oxygen Species/metabolism ; Signal Transduction

Macrophage colony-stimulating factor (M-CSF) is known as one of the factors essential for osteoclast development. In the present study, we examined effects of M-CSF on the apoptotic pathway of osteoclast precursors and their underlying molecular mechanisms. Osteoclast precursors underwent apoptosis in the absence of M-CSF, even in the presence of receptor activator of NF-kB ligand (RANKL). Active caspase-3 and -9 were detected in the osteoclast precursors and treatments of precursors with their specific inhibitors (Z- DEVD-FMK and Z-LEHD-FMK) decreased the apoptosis. M-CSF decreased apoptosis in a dose-dependent manner with decreasing in active caspases-3 and -9 levels and up-regulating Bcl-XL. Those effects of M-CSF on inhibiting apoptosis of osteoclasts precursor by regulating anti-apoptotic signals was more effective when combined with RANKL. These results demonstrate that M-CSF acts as a survival factor for the osteoclast precursors. Furthermore, it is believed that the apoptosis of osteoclast precursors may be involved in the activation of caspase-9 and that M-CSF may promote their survival through Bcl-XL-induced inhibition of caspase-9 activation.
Animals ; Apoptosis/drug effects/physiology ; Carrier Proteins/pharmacology ; Caspases/antagonists & inhibitors/drug effects/metabolism ; Cell Survival/drug effects ; Cells, Cultured ; Cysteine Proteinase Inhibitors/pharmacology ; Enzyme Activation/drug effects ; Female ; Macrophage Colony-Stimulating Factor/*pharmacology ; Membrane Glycoproteins/pharmacology ; Mice ; Mice, Inbred ICR ; Oligopeptides/pharmacology ; Osteoclasts/*cytology/drug effects ; Proto-Oncogene Proteins c-bcl-2/drug effects/*metabolism ; Stem Cells/cytology/*drug effects ; Up-Regulation

BACKGROUND/AIMS: The present study was performed to determine the effects of the ethyl acetate extract of Cudrania tricuspidata (EACT) on interleukin (IL)-1beta-stimulated receptor activator of NF-kappaB ligand (RANKL)-mediated osteoclast differentiation. METHODS: Bone marrow cells were harvested from 6-week-old male imprinting control region mice, and the differentiation of osteoclasts from these cells was evaluated by tartrate-resistant acid phosphatase and resorption pit formation assay. Phosphorylated extracellular signal regulated kinase (p-ERK), phosphorylated p38, phosphorylated c-Jun amino-terminal kinase, NF-kappaB (p65), IkappaBalpha, c-Fos, and nuclear factor of activated T-cells c1 (NFATc1) expression was examined by immunoblotting and quantitative reverse transcription-polymerase chain reaction. RESULTS: EACT inhibits IL-1beta-stimulated RANKL-mediated osteoclast differentiation. EACT also inhibits IL-1beta-stimulated RANKL-mediated phosphorylation of ERK 1/2, p38 mitogen activated protein kinase, and expression of c-Fos and NFATc1. CONCLUSIONS: These results suggest that EACT may be involved in the inhibition of bone loss by preventing osteoclast formation and may be used to manage bone destruction in inflammatory diseases, such as rheumatoid arthritis.
*Acetates ; Animals ; Bone Marrow Cells/cytology/drug effects/metabolism ; Cell Differentiation/drug effects/physiology ; Cell Survival/drug effects/physiology ; Cells, Cultured ; Down-Regulation/drug effects ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Interleukin-1beta/*pharmacology ; MAP Kinase Signaling System/*drug effects/physiology ; Male ; Mice ; Mice, Inbred ICR ; *Moraceae ; NFATC Transcription Factors/metabolism ; *Osteoclasts/cytology/drug effects/metabolism ; Plant Extracts/*pharmacology ; Proto-Oncogene Proteins c-fos/metabolism ; RANK Ligand/metabolism ; Stem Cells/cytology/drug effects/metabolism ; p38 Mitogen-Activated Protein Kinases/metabolism

OBJECTIVETo investigate the treatment effects and mechanisms of pyrroloquinoline quinine(PQQ) on defective teeth and mandible in Bmi-1 knockout mice.

METHODSMale and female Bmi1(+/-) mice were paired with each other from the same nest. At the age of 7 weeks, the mice were divided into three groups, the wild type mice received normal diet(10 mice, WT group), Bmi1(-/-) mice received normal diet (10 mice, BKO group), and the Bmi1(-/-) mice received normal diet and PQQ diet(10 mice, BKO+PQQ group). X-ray and micro- CT were used to detect mandible and dental size and bone mineral density. HE staining, histochemical and immunohistochemical methods were respectively used to detect alveolar bone thickness of cortical bone, predentin thickness of mandibular first molar, mandibular osteoblast number and osteoclast number. Flow cytometry was used to detect reactive oxygen species(ROS) levels of various organs(femur, thymus and liver). The data were statistically analyzed with one-way ANOVA and t test.

RESULTSCompared with BKO mice, BKO+PQQ mice partially rescued total body phenotype, increased body weight and prolonged survival time. X- ray and micro- CT showed the size of the mandible and teeth and bone mineral density of PQQ+BKO mice increased compared with BKO mice. In PQQ+BKO mice, mandibular alveolar bone cortical thickness [(68.65 ± 0.25) µm] was significantly different from that in BKO mice [(42.45 ± 0.35) µm] (P<0.01). There was significant difference in predentin thickness of mandibular first molar between PQQ+BKO mice [(4.25 ± 0.15) µm] and BKO mice [(31.55 ± 0.35) µm] (P<0.001). The number of osteoblasts in the mandible of BKO+PQQ mice [(38.45 ± 0.25) cell/mm³] was significantly higher than that in the BKO mice [(18.15 ± 0.55) cell/mm³] (P<0.01). However, the number of osteoclasts in the BKO+PQQ mice [(9.45 ± 0.25) cell/mm³] was significantly lower than that in the BKO group [(14.25 ± 0.35) cell/mm³] (P<0.01). Compared with the BKO group, ROS levels of the femur, thymus and liver in the BKO+PQQ mice were significantly decreased (P<0.01).

CONCLUSIONSThe results indicate that PQQ may have treatment effects on defective teeth and mandible through promoting osteoblast bone formation and reducing osteoclast bone resorption, scavenging ROS and reducing DNA damage.

Animals ; Bone Density ; drug effects ; Bone Resorption ; prevention & control ; Female ; Male ; Mandible ; drug effects ; pathology ; physiopathology ; Mice ; Mice, Knockout ; Organ Size ; Osteoblasts ; cytology ; drug effects ; Osteoclasts ; cytology ; drug effects ; Osteogenesis ; drug effects ; physiology ; PQQ Cofactor ; pharmacology ; Polycomb Repressive Complex 1 ; genetics ; Proto-Oncogene Proteins ; genetics ; Reactive Oxygen Species ; analysis ; Tooth ; drug effects ; pathology ; physiopathology ; X-Ray Microtomography