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Osteoclast Number (osteoclast + number)
Selected AbstractsAccentuated Ovariectomy-Induced Bone Loss and Altered Osteogenesis in Heterozygous N-Cadherin Null Mice,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2006Chung Fang Lai Abstract Ovariectomy-induced bone loss is accentuated in mice with germline Cdh2 haploinsufficiency, the result of a decreased osteoblastogenesis in the face of normal osteoclast number. Reduced N-cadherin abundance in these mice decreases cell,cell adhesion and alters signaling pathways important for osteoblast commitment and differentiation, thus providing in vivo evidence that N-cadherin,mediated cell,cell interactions are involved in homeostatic responses to increased bone remodeling. Introduction: We have shown that targeted expression of a dominant negative truncated form of N-cadherin (Cdh2) delays acquisition of peak bone mass in mice and retards osteoblast differentiation. We tested the role of this molecule in the skeletal homeostatic response to ovariectomy in mice with germline Cdh2 haploinsufficiency. Materials and Methods: Heterozygous Cdh2 null (Cdh2+/,) and wildtype mice were ovariectomized and followed up to 13 weeks by in vivo radiodensitometric and ex vivo histologic assessment of bone mass and turnover. Cells isolated from wildtype and Cdh2+/, mice were used to determine the alterations in bone cell function produced by partial loss of N-cadherin. Results: Bone mass was not significantly different between Cdh2+/, and wildtype littermates, but on ovariectomy, bone loss in Cdh2+/, mice was initially slower, but with time it became significantly greater than in wildtype mice. This accentuated bone loss was associated with lower osteoblast number and serum osteocalcin levels, with no differences in bone resorption. Although development of calcified nodules was faster in calvaria cells isolated from Cdh2+/, mice relative to Cdh2+/+ cells, bone marrow osteogenic precursors were lower in the former than in the latter genotypes. Cdh2 expression was downregulated with differentiation in wildtype calvaria cells, whereas cadherin-11 abundance remained unchanged. Furthermore, cell,cell adhesion (postconfluence) was decreased among heterozygous calvaria cells, as was cell proliferation (preconfluence), relative to wildtype cells. Finally, the abundance and cellular distribution of ,-catenin was minimally decreased in Cdh2+/, cells, whereas mitogen-activated protein kinase (MAPK) signaling was more active in Cdh2 insufficient cells. Conclusions:Cdh2 is involved in the homeostatic bone formation response to ovariectomy, presumably by regulating osteoprogenitors number and differentiation through stabilization of cell,cell adhesion and/or signaling modulation. [source] A Nonprostanoid EP4 Receptor Selective Prostaglandin E2 Agonist Restores Bone Mass and Strength in Aged, Ovariectomized RatsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2006Hua Zhu Ke MD Abstract CP432 is a newly discovered, nonprostanoid EP4 receptor selective prostaglandin E2 agonist. CP432 stimulates trabecular and cortical bone formation and restores bone mass and bone strength in aged ovariectomized rats with established osteopenia. Introduction: The purpose of this study was to determine whether a newly discovered, nonprostanoid EP4 receptor selective prostaglandin E2 (PGE2) agonist, CP432, could produce bone anabolic effects in aged, ovariectomized (OVX) rats with established osteopenia. Materials and Methods: CP432 at 0.3, 1, or 3 mg/kg/day was given for 6 weeks by subcutaneous injection to 12-month-old rats that had been OVX for 8.5 months. The effects on bone mass, bone formation, bone resorption, and bone strength were determined. Results: Total femoral BMD increased significantly in OVX rats treated with CP432 at all doses. CP432 completely restored trabecular bone volume of the third lumbar vertebral body accompanied with a dose-dependent decrease in osteoclast number and osteoclast surface and a dose-dependent increase in mineralizing surface, mineral apposition rate, and bone formation rate-tissue reference in OVX rats. CP432 at 1 and 3 mg/kg/day significantly increased total tissue area, cortical bone area, and periosteal and endocortical bone formation in the tibial shafts compared with both sham and OVX controls. CP432 at all doses significantly and dose-dependently increased ultimate strength in the fifth lumber vertebral body compared with both sham and OVX controls. At 1 and 3 mg/kg/day, CP432 significantly increased maximal load in a three-point bending test of femoral shaft compared with both sham and OVX controls. Conclusions: CP432 completely restored trabecular and cortical bone mass and strength in established osteopenic, aged OVX rats by stimulating bone formation and inhibiting bone resorption on trabecular and cortical surfaces. [source] Capsaicin-Sensitive Sensory Neurons Contribute to the Maintenance of Trabecular Bone Integrity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2005Sarah C Offley Abstract This investigation used capsaicin to selectively lesion unmyelinated sensory neurons in rats. Neuronal lesioning induced a loss of trabecular integrity, reduced bone mass and strength, and depleted neuropeptides in nerve and bone. These data suggest that capsaicin-sensitive sensory nerves contribute to trabecular bone integrity. Introduction: Familial dysautomia is an autosomal recessive disease in which patients suffer from unmyelinated sensory neuron loss, reduced BMD, and frequent fractures. It has been proposed that the loss of neurotransmitters synthesized by unmyelinated neurons adversely affects bone integrity in this hereditary syndrome. The purpose of this study was to determine whether small sensory neurons are required for the maintenance of bone integrity in rats. Materials and Methods: Ten-month-old male Sprague-Dawley rats were treated with either capsaicin or vehicle. In vivo DXA scanning and ,CT scanning, and histomorphometry were used to evaluate BMD, structure, and cellular activity. Bone strength was measured in distal femoral sections. Body weight and gastrocnemius/soleus weights were measured and spontaneous locomotor activity was monitored. Peroneal nerve morphometry was evaluated using light and electron microscopy. Substance P and calcitonin gene-related peptide (CGRP) content in the sciatic nerve and proximal tibia were determined by enzyme immunoassay (EIA). Substance P signaling was measured using a sciatic nerve stimulation extravasation assay. Results: Four weeks after capsaicin treatment, there was a loss of BMD in the metaphyses of the tibia and femur. In the proximal tibia, the osteoclast number and surface increased, osteoblast activity and bone formation were impaired, and trabecular bone volume and connectivity were diminished. There was also a loss of bone strength in the distal femur. No changes occurred in body weight, 24-h grid-crossing activity, weight bearing, or muscle mass after capsaicin treatment, indicating that skeletal unloading did not contribute to the loss of bone integrity. Capsaicin treatment destroyed 57% of the unmyelinated sensory axons, reduced the substance P and CGRP content in the sciatic nerve and proximal tibia, and inhibited neurogenic extravasation. Conclusion: These results support the hypothesis that capsaicin-sensitive sensory neurons contribute to the maintenance of trabecular bone integrity. Capsaicin-sensitive neurons have efferent functions in the tissues they innervate, effects mediated by transmitters released from the peripheral nerve terminals. We postulate that the deleterious effects of capsaicin treatment on trabecular bone are mediated by reductions in local neurotransmitter content and release. [source] Long-Term Dosing of Arzoxifene Lowers Cholesterol, Reduces Bone Turnover, and Preserves Bone Quality in Ovariectomized Rats,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2002Yanfei L. Ma M.D. Abstract Long-term effects of a new selective estrogen receptor modulator (SERM) arzoxifene were examined in ovariectomized (OVX) rats. Arzoxifene was administered postoperatively (po) at 0.1 mg/kg per day or 0.5 mg/kg per day to 4-month-old rats, starting 1 week after OVX for 12 months. At study termination, body weights for arzoxifene groups were 16,17% lower than OVX control, which was caused by mainly reduced gain of fat mass. Longitudinal analysis of the proximal tibial metaphysis (PTM) by computed tomography (CT) at 0, 2, 4, 6, 9, and 12 months showed that OVX induced a 22% reduction in bone mineral density (BMD) at 2 months, which narrowed to a 12% difference between sham-operated (sham) and OVX rats by 12 months. Both doses of arzoxifene prevented the OVX-induced decline in BMD. Histomorphometry of the PTM showed that arzoxifene prevented bone loss by reducing osteoclast number in OVX rats. Arzoxifene maintained bone formation indices at sham levels and preserved trabecular number above OVX controls. Micro-CT analysis of lumbar vertebrae showed similar preservation of BMD compared with OVX, which were not different from sham. Compression testing of the vertebra and three-point bending testing of femoral shaft showed that strength and toughness were higher for arzoxifene-treated animals compared with OVX animals. Arzoxifene reduced serum cholesterol by 44,59% compared with OVX. Uteri wet weight from arzoxifene animals was 38,40% of sham compared with OVX rats, which were 29% of sham. Histology of the uterine endometrium showed that cell heights from both doses of arzoxifene were not significantly different from OVX controls. In summary, treatment of OVX rats with arzoxifene for nearly one-half of a lifetime maintained beneficial effects on cholesterol and the skeleton. These data suggest that arzoxifene may be a useful therapeutic agent for osteoporosis in postmenopausal women. [source] Lasofoxifene (CP-336,156) Protects Against the Age-Related Changes in Bone Mass, Bone Strength, and Total Serum Cholesterol in Intact Aged Male RatsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2001Hua Zhu Ke Abstract The purpose of this study was to evaluate if long-term (6 months) treatment with lasofoxifene (LAS), a new selective estrogen receptor modulator (SERM), can protect against age-related changes in bone mass and bone strength in intact aged male rats. Sprague-Dawley male rats at 15 months of age were treated (daily oral gavage) with either vehicle (n = 12) or LAS at 0.01 mg/kg per day (n = 12) or 0.1 mg/kg per day (n = 11) for 6 months. A group of 15 rats was necropsied at 15 months of age and served as basal controls. No significant change was found in body weight between basal and vehicle controls. However, an age-related increase in fat body mass (+42%) and decrease in lean body mass (,8.5%) was observed in controls. Compared with vehicle controls, LAS at both doses significantly decreased body weight and fat body mass but did not affect lean body mass. No significant difference was found in prostate wet weight among all groups. Total serum cholesterol was significantly decreased in all LAS-treated rats compared with both the basal and the vehicle controls. Both doses of LAS treatment completely prevented the age-related increase in serum osteocalcin. Peripheral quantitative computerized tomography (pQCT) analysis at the distal femoral metaphysis indicated that the age-related decrease in total density, trabecular density, and cortical thickness was completely prevented by treatment with LAS at 0.01 mg/kg per day or 0.1 mg/kg per day. Histomorphometric analysis of proximal tibial cancellous bone showed an age-related decrease in trabecular bone volume (TBV; ,46%), trabecular number (Tb.N), wall thickness (W.Th), mineral apposition rate, and bone formation rate-tissue area referent. Moreover, an age-related increase in trabecular separation (Tb.Sp) and eroded surface was observed. LAS at 0.01 mg/kg per day or 0.1 mg/kg per day completely prevented these age-related changes in bone mass, bone structure, and bone turnover. Similarly, the age-related decrease in TBV and trabecular thickness (Tb.Th) and the age-related increase in osteoclast number (Oc.N) and osteoclast surface (Oc.S) in the third lumbar vertebral cancellous bone were completely prevented by treatment with LAS at both doses. Further, LAS at both doses completely prevented the age-related decrease in ultimate strength (,47%) and stiffness (,37%) of the fifth lumbar vertebral body. These results show that treatment with LAS for 6 months in male rats completely prevents the age-related decreases in bone mass and bone strength by inhibiting the increased bone resorption and bone turnover associated with aging. Further, LAS reduced total serum cholesterol and did not affect the prostate weight in these rats. Our data support the potential use of a SERM for protecting against the age-related changes in bone and serum cholesterol in elderly men. [source] Moderate Alcohol Consumption Suppresses Bone Turnover in Adult Female RatsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2001R. T. Turner Abstract Chronic alcohol abuse is a major risk factor for osteoporosis but the effects of moderate drinking on bone metabolism are largely uninvestigated. Here, we studied the long-term dose-response (0, 3, 6, 13, and 35% caloric intake) effects of alcohol on cancellous bone in the proximal tibia of 8-month-old female rats. After 4 months of treatment, all alcohol-consuming groups of rats had decreased bone turnover. The inhibitory effects of alcohol on bone formation were dose dependent. A reduction in osteoclast number occurred at the lowest level of consumption but there were no further reductions with higher levels of consumption. An imbalance between bone formation and bone resorption at higher levels of consumption of alcohol resulted in trabecular thinning. Our observations in rats raise the concern that moderate consumption of alcoholic beverages in humans may reduce bone turnover and potentially have detrimental effects on the skeleton. [source] 2-methoxyestradiol-mediated anti-tumor effect increases osteoprotegrin expression in osteosarcoma cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2010Michaela B. Benedikt Abstract Osteosarcoma is a bone tumor that frequently develops during adolescence. 2-Methoxyestradiol (2-ME), a naturally occurring metabolite of 17,-estradiol, induces cell cycle arrest and cell death in human osteosarcoma cells. To investigate whether the osteoprotegrin (OPG) protein plays a role in 2-ME actions, we studied the effect of 2-ME treatment on OPG gene expression in human osteosarcoma cells. 2-ME treatment induced OPG gene promoter activity and mRNA levels. Also, Western blot analysis showed that 2-ME treatment increased OPG protein levels in MG63, KHOS, 143B and LM7 osteosarcoma cells by 3-, 1.9-, 2.8-, and 2.5-fold, respectively, but did not affect OPG expression in normal bone cells. In addition, increases in OPG protein levels were observed in osteosarcoma cell culture media after 3 days of 2-ME treatment. The effect of 2-ME on osteosarcoma cells was ligand-specific as parent estrogen, 17,-estradiol and a tumorigenic estrogen metabolite, 16,-hydroxyestradiol, which do not affect osteosarcoma cell cycle and cell death, had no effect on OPG protein expression. Furthermore, co-treating osteosarcoma cells with OPG protein did not further enhance 2-ME-mediated anti-tumor effects. OPG-released in 2-ME-treated cultures led to an increase in osteoblastic activity and a decrease in osteoclast number, respectively. These findings suggest that OPG is not directly involved in 2-ME-mediated anti-proliferative effects in osteosarcoma cells, but rather participates in anti-resorptive functions of 2-ME in bone tumor environment. J. Cell. Biochem. 109: 950,956, 2010. © 2010 Wiley-Liss, Inc. [source] Bone resorption activity of osteolytic metastatic lung and breast cancersJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2004Lih-Yuann Shih Abstract Production of bone resorption mediators and bone resorption activity were compared among osteolytic metastatic cancers, normal bone tissues, and soft tissue metastatic cancers to search for the possible factors leading to cancer-induced bone resorption. Twenty-five patients with untreated osteolytic metastatic breast or non-small cell lung cancers consisted of the study group. Normal bone tissues obtained from the same patient were used as internal controls; and tumor tissues from patients with soft tissue metastasis were used as external controls. Serum and urinary bone turnover markers were measured. Tissues harvested during surgery were subjected to tissue culture. The levels of prostaglandin E2 (PGE2), tumor necrosis factor-, (TNF-,), and interleukin-6 (IL-6) in the supernatant after 72 h of culture were measured. Bone resorption activity was measured by calcium release from cultured calvarias, and bone volume as well as osteoclast number in bone sections. Patients with osteolytic metastatic cancers showed significantly decreased serum osteocalcin, increased serum alkaline phosphatase, and urinary deoxypyridinoline levels. Osteolytic metastatic cancers produced significantly more PGE2 than both controls. Conditioned medium from osteolytic metastatic tumors showed significantly enhanced bone resorption activity, and indomethacin significantly reduced this activity. Levels of PGE2, and bone resorption activity increased in osteolytic tumor tissues than soft tissue metastatic tissues in the same patient indicated that the same tumor cells might respond differently to different microenvironments. Our observation showed that PGE2 was produced by osteolytic metastatic cancers and stimulated bone resorption in mice calvarias. PGE2 inhibitor may be applicable in reducing bone resorption by osteolytic metastatic cancers. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Expression of receptor activator of nuclear factor kappa B ligand relates to inflammatory bone resorption, with or without occlusal trauma, in ratsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2007Y. Yoshinaga Background and Objective:, Receptor activator of nuclear factor kappa B ligand (RANKL) is an important factor in osteoclast differentiation, activation and survival; however, its involvement in inflammatory bone resorption, with or without occlusal trauma, is unclear. The purpose of the present study was to investigate the distribution of RANKL-expressing cells in rat periodontium during lipopolysaccharide-induced inflammation with or without occlusal trauma. Material and Methods:, Lipopolysaccharide was injected into rat gingiva of the lower left first molar to induce inflammation. In addition, the occlusal surface of the upper left first molar of rat was raised by placing a gold inlay to induce occlusal trauma in the lower left first molars. The distribution of RANKL-expressing cells was immunohistochemically observed. Results:, In the inflammatory model, many osteoclasts were observed at the apical inter-radicular septum on day 5 and they were reduced by day 10. On the other hand, in the inflammatory model with occlusal trauma, many osteoclasts were still observed on day 10. RANKL expression was similar to the changes in osteoclast number. The expression of RANKL increased in endothelial cells, inflammatory cells and periodontal ligament cells. Conclusion:, These findings clearly demonstrated that RANKL expression on endothelial cells, inflammatory cells and periodontal ligament cells is involved in inflammatory bone resorption and the expression is enhanced by traumatic occlusion. These results suggest that RANKL expression on these cells is closely involved in the increase of osteoclasts induced by occlusal trauma. [source] TOCOTRIENOL OFFERS BETTER PROTECTION THAN TOCOPHEROL FROM FREE RADICAL-INDUCED DAMAGE OF RAT BONECLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2005NS Ahmad SUMMARY 1.,Free radicals generated by ferric nitrilotriacetate (FeNTA) can activate osteoclastic activity and this is associated with elevation of the bone resorbing cytokines interleukin (IL)-1 and IL-6. In the present study, we investigated the effects of 2 mg/kg FeNTA (2 mg iron/kg) on the levels of serum IL-1 and IL-6 with or without supplementation with a palm oil tocotrienol mixture or ,-tocopherol acetate in Wistar rats. 2.,The FeNTA was found to elevate levels of IL-1 and IL-6. Only the palm oil tocotrienol mixture at doses of 60 and 100 mg/kg was able to prevent FeNTA-induced increases in IL-1 (P < 0.01). Both the palm oil tocotrienol mixture and ,-tocopherol acetate, at doses of 30, 60 and 100 mg/kg, were able to reduce FeNTA-induced increases in IL-6 (P < 0.05). Therefore, the palm oil tocotrienol mixture was better than pure ,-tocopherol acetate in protecting bone against FeNTA (free radical)-induced elevation of bone-resorbing cytokines. 3.,Supplementation with the palm oil tocotrienol mixture or ,-tocopherol acetate at 100 mg/kg restored the reduction in serum osteocalcin levels due to ageing, as seen in the saline (control) group (P < 0.05). All doses of the palm oil tocotrienol mixture decreased urine deoxypyridinoline cross-link (DPD) significantly compared with the control group, whereas a trend for decreased urine DPD was only seen for doses of 60 mg/kg onwards of ,-tocopherol acetate (P < 0.05). 4.,Bone histomorphometric analyses have shown that FeNTA injections significantly lowered mean osteoblast number (P < 0.001) and the bone formation rate (P < 0.001), but raised osteoclast number (P < 0.05) and the ratio of eroded surface/bone surface (P < 0.001) compared with the saline (control) group. Supplementation with 100 mg/kg palm oil tocotrienol mixture was able to prevent all these FeNTA-induced changes, but a similar dose of ,-tocopherol acetate was found to be effective only for mean osteoclast number. Injections of FeNTA were also shown to reduce trabecular bone volume (P < 0.001) and trabecular thickness (P < 0.05), whereas only supplementation with 100 mg/kg palm oil tocotrienol mixture was able to prevent these FeNTA-induced changes. [source] Are Nonresorbing Osteoclasts Sources of Bone Anabolic Activity?,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2007Morten A Karsdal PhD Abstract Some osteopetrotic mutations lead to low resorption, increased numbers of osteoclasts, and increased bone formation, whereas other osteopetrotic mutations lead to low resorption, low numbers of osteoclasts, and decreased bone formation. Elaborating on these findings, we discuss the possibility that osteoclasts are the source of anabolic signals for osteoblasts. In normal healthy individuals, bone formation is coupled to bone resorption in a tight equilibrium. When this delicate balance is disturbed, the net result is pathological situations, such as osteopetrosis or osteoporosis. Human osteopetrosis, caused by mutations in proteins involved in the acidification of the resorption lacuna (ClC-7 or the a3-V-ATPase), is characterized by decreased resorption in face of normal or even increased bone formation. Mouse mutations leading to ablation of osteoclasts (e.g., loss of macrophage-colony stimulating factor [M-CSF] or c- fos) lead to secondary negative effects on bone formation, in contrast to mutations where bone resorption is abrogated with sustained osteoclast numbers, such as the c-src mice. These data indicate a central role for osteoclasts, and not necessarily their resorptive activity, in the control of bone formation. In this review, we consider the balance between bone resorption and bone formation, reviewing novel data that have shown that this principle is more complex than originally thought. We highlight the distinct possibility that osteoclast function can be divided into two more or less separate functions, namely bone resorption and stimulation of bone formation. Finally, we describe the likely possibility that bone resorption can be attenuated pharmacologically without the undesirable reduction in bone formation. [source] Diminished Bone Formation During Diabetic Fracture Healing is Related to the Premature Resorption of Cartilage Associated With Increased Osteoclast Activity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2007Rayyan A Kayal Abstract Histological and molecular analysis of fracture healing in normal and diabetic animals showed significantly enhanced removal of cartilage in diabetic animals. Increased cartilage turnover was associated with elevated osteoclast numbers, a higher expression of genes that promote osteoclastogenesis, and diminished primary bone formation. Introduction: Diminished bone formation, an increased incidence of nonunions, and delayed fracture healing have been observed in animal models and in patients with diabetes. Fracture healing is characterized by the formation of a stabilizing callus in which cartilage is formed and then resorbed and replaced by bone. To gain insight into how diabetes affects fracture healing, studies were carried out focusing on the impact of diabetes on the transition from cartilage to bone. Materials and Methods: A low-dose treatment protocol of streptozotocin in CD-1 mice was used to induce a type 1 diabetic condition. After mice were hyperglycemic for 3 weeks, controlled closed simple transverse fractures of the tibia were induced and fixed by intramedullary pins. Histomorphometric analysis of the tibias obtained 12, 16, and 22 days after fracture was performed across the fracture callus at 0.5 mm proximal and distal increments using computer-assisted image analysis. Another group of 16-day samples were examined by ,CT. RNA was isolated from a separate set of animals, and the expression of genes that reflect the formation and removal of cartilage and bone was measured by real-time PCR. Results: Molecular analysis of collagen types II and × mRNA expression showed that cartilage formation was the same during the initial period of callus formation. Histomorphometric analysis of day 12 fracture calluses showed that callus size and cartilage area were also similar in normoglycemic and diabetic mice. In contrast, on day 16, callus size, cartilage tissue, and new bone area were 2.0-, 4.4-, and 1.5-fold larger, respectively, in the normoglycemic compared with the diabetic group (p < 0.05). Analysis of ,CT images indicated that the bone volume in the normoglycemic animals was 38% larger than in diabetic animals. There were 78% more osteoclasts in the diabetic group compared with the normoglycemic group (p < 0.05) on day 16, consistent with the reduction in cartilage. Real-time PCR showed significantly elevated levels of mRNA expression for TNF-,, macrophage-colony stimulating factor, RANKL, and vascular endothelial growth factor-A in the diabetic group. Similarly, the mRNA encoding ADAMTS 4 and 5, major aggrecanases that degrade cartilage, was also elevated in diabetic animals. Conclusions: These results suggest that impaired fracture healing in diabetes is characterized by increased rates of cartilage resorption. This premature loss of cartilage leads to a reduction in callus size and contributes to decreased bone formation and mechanical strength frequently reported in diabetic fracture healing. [source] Active caspase-3 is required for osteoclast differentiationJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2006K.H. Szymczyk Based on our earlier observation that caspase-3 is present in osteoclasts that are not undergoing apoptosis, we investigated the role of this protein in the differentiation of primary osteoclasts and RAW264.7 cells (Szymczyk KH, et al., 2005, Caspase-3 activity is necessary for RANKL-induced osteoclast differentiation. The Proceedings of the 8th ICCBMT). We noted that osteoclast numbers are decreased in long bones of procaspase-3 knockout mice and that receptor activator of NF-,B ligand (RANKL) does not promote differentiation of isolated preosteoclasts. In addition, after treatment with inhibitors of caspase-3 activity, neither the wild-type primary nor the RAW264.7 cells express TRAP or became multinucleated. We found that immediately following RANKL treatment, procaspase-3 is cleaved and the activated protein is localized to lipid regions of the plasma membrane and the cytosol. We developed RAW264.7 procaspase-3 knockdown clonal cell lines using RNAi technology. Again, treatment with RANKL fails to induce TRAP activity or multinucleation. Finally, we evaluated NF-,B in procaspase-3 silenced cells. We found that RANKL treatment prevented activation and nuclear translocation of NF-,B. Together these findings provide direct support for the hypothesis that caspase-3 activity is required for osteoclast differentiation. J. Cell. Physiol. 209: 836,844, 2006. © 2006 Wiley-Liss, Inc. [source] Efficacy of ex vivo OPG gene therapy in preventing wear debris induced osteolysisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2002J. Jeffrey Goater Aseptic loosening of prosthetic implants remains a serious orthopaedic problem and the greatest limitation to total joint arthroplasty. Central to the etiology of aseptic loosening is periprosthetic osteolysis at the bone-implant interface, which is caused by wear debris-induced inflammation. This inflammation produces the critical osteoclast differentiation factor RANKL, which directly stimulates osteoclastogenesis and osteoclastic bone resorption. A dominant factor known to counteract this process is the natural RANKL receptor antagonist protein OPG. Here we explore the potential of ex vivo OPG gene therapy for aseptic loosening by evaluating the efficacy of stably transfected fibroblast-like synoviocytes (FLS) expressing OPG in preventing wear debris-induced osteoclastogenesis, in a mouse calvaria model. Although the stably transfected fibroblasts produced small amounts of OPG (0.3 ng/ml/72 h/106 cells), this protein was very effective in preventing osteoclastic resorption as determined in a bone wafer assay. More importantly, implantation of 107 FLS,OPG, together with 30 mg of Ti wear debris, onto the calvaria of mice, completely inhibited osteoclastogenesis 3 days after surgery. Animals given FLS-LacZ control cells, which persisted for 3 days as determined by X-gal staining, together with the Ti particles, had a 6-fold increase in osteoclastogenesis compared to controls without Ti. This increased osteoclastogenesis was completely inhibited by the FLS-OPG, as osteoclast numbers in the calvaria of these animals were similar to that seen in the SHAM controls. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] The proteasome inhibitor, bortezomib suppresses primary myeloma and stimulates bone formation in myelomatous and nonmyelomatous bones in vivo,AMERICAN JOURNAL OF HEMATOLOGY, Issue 1 2009Angela Pennisi Multiple myeloma (MM), a hematologic malignancy of terminally differentiated plasma cells is closely associated with induction of osteolytic bone disease, induced by stimulation of osteoclastogenesis and suppression of osteoblastogenesis. The ubiquitin-proteasome pathway regulates differentiation of bone cells and MM cell growth. The proteasome inhibitor, bortezomib, is a clinical potent antimyeloma agent. The main goal of this study was to investigate the effect of bortezomib on myeloma-induced bone resorption and tumor growth in SCID-rab mice engrafted with MM cells from 16 patients. Antimyeloma response of bortezomib, which was evident in >50% of 16 experiments and resembled clinical response, was associated with significant increased bone mineral density (BMD) and osteoblast numbers, and reduced osteoclast numbers in myelomatous bones. This bone anabolic effect, which was also visualized on X-ray radiographs and confirmed by static and dynamic histomorphometric analyses, was unique to bortezomib and was not observed in hosts responding to melphalan, a chemotherapeutic drug widely used to treat MM. Bortezomib also increased BMD and osteoblasts number and reduced osteoclasts number in nonmyelomatous implanted bones. In vitro bortezomib directly suppressed human osteoclast formation and promoted maturation of osteoblasts. We conclude that bortezomib promotes bone formation in myelomatous and nonmyelomatous bones by simultaneously inhibiting osteoclastogenesis and stimulating osteoblastogenesis. As clinical and experimental studies indicate that bone disease is both a consequence and necessity of MM progression our results suggest and that bortezomib's effects on bone remodeling contribute to the antimyeloma efficacy of this drug. Am. J. Hematol., 2009. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||