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Bone Marrow Cultures (bone + marrow_culture)
Selected AbstractsProstaglandin E2 -Mediated Anabolic Effect of a Novel Inhibitor of Phosphodiesterase 4, XT-611, in the In Vitro Bone Marrow Culture,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2003Ken-Ichi Miyamoto Abstract The mechanism of osteoblast formation by a novel PDE4 inhibitor, XT-611, was studied in the in vitro bone marrow culture system. The compound potentiated the osteoblast differentiation through accumulation of cyclic AMP after autocrine stimulation of EP4 receptor by PGE2 in pro-osteoblastic cells. Introduction: We previously reported that inhibitors of phosphodiesterase (PDE)4 isoenzyme increase osteoblast formation in an in vitro bone marrow culture system and inhibit bone loss in animal osteoporosis models. Here we investigated the mechanism of the effect of a novel PDE4 inhibitor, 3,4-dipropyl-4,5,7,8-tetrahydro-3H -imidazo[1,2- i]-purin-5-one (XT-611), on osteoblast formation in the in vitro bone marrow culture system. Materials and Methods: Rodent bone marrow cells were cultured in the presence of 0.2 mM ascorbic acid phosphate ester, 1 mM ,-glycerophosphate, and 10 nM dexamethasone for 10 days. Drug treatments were done for 24 h on day 3 of culture. Results: PDE4 inhibitors, including XT-611, but not PDE3 and PDE5 inhibitors, increased mineralized nodule formation in rat and mouse bone marrow cell cultures. During culture of the bone marrow cells, prostaglandin E2 (PGE2) production increased with a peak on day 4, but the increase was completely inhibited by indomethacin, an unselective cyclo-oxygenase (COX) inhibitor. Spontaneous and XT-611-induced mineralized-nodule formation was also inhibited by indomethacin and COX-2 inhibitors, in a similar potential. Alkaline phosphatase-positive nodule formation in the absence or presence of XT-611 was inhibited by an antagonist of EP4 receptor, AH23848B, and synergistically potentiated by 11-deoxy-PGE1, but it was not influenced by other EP antagonists and agonists examined. The expression of PDE4 and EP4 mRNAs was observed in bone marrow cells. The effect of XT-611 was also confirmed to involve an increase of cyclic AMP and the cyclic AMP-dependent protein kinase pathway. Conclusion: These results suggest that PGE2 stimulates differentiation of osteoblast progenitor cells through the EP4 receptor in an autocrine manner, and the PDE4 inhibitor potentiates the differentiation by inhibiting hydrolysis of cyclic AMP in the cells. [source] Activation of Protease-Activated Receptor-2 Leads to Inhibition of Osteoclast Differentiation,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2004Rosealee Smith Abstract PAR-2 is expressed by osteoblasts and activated by proteases present during inflammation. PAR-2 activation inhibited osteoclast differentiation induced by hormones and cytokines in mouse bone marrow cultures and may protect bone from uncontrolled resorption. Introduction: Protease-activated receptor-2 (PAR-2), which is expressed by osteoblasts, is activated specifically by a small number of proteases, including mast cell tryptase and factor Xa. PAR-2 is also activated by a peptide (RAP) that corresponds to the "tethered ligand" created by cleavage of the receptor's extracellular domain. The effect of activating PAR-2 on osteoclast differentiation was investigated. Materials and Methods: Mouse bone marrow cultures have been used to investigate the effect of PAR-2 activation on osteoclast differentiation induced by parathyroid hormone (PTH), 1,25 dihydroxyvitamin D3 [1,25(OH)2D3], and interleukin-11 (IL-11). Expression of PAR-2 by mouse bone marrow, mouse bone marrow stromal cell-enriched cultures, and the RAW264.7 osteoclastogenic cell line was demonstrated by RT-PCR. Results: RAP was shown to inhibit osteoclast differentiation induced by PTH, 1,25(OH)2D3, or IL-11. Semiquantitative RT-PCR was used to investigate expression of mediators of osteoclast differentiation induced by PTH, 1,25(OH)2D3, or IL-11 in mouse bone marrow cultures and primary calvarial osteoblast cultures treated simultaneously with RAP. In bone marrow and osteoblast cultures treated with PTH, 1,25(OH)2D3, or IL-11, RAP inhibited expression of RANKL and significantly suppressed the ratio of RANKL:osteoprotegerin expression. Activation of PAR-2 led to reduced expression of prostaglandin G/H synthase-2 in bone marrow cultures treated with PTH, 1,25(OH)2D3, or IL-11. RAP inhibited PTH- or 1,25(OH)2D3 -induced expression of IL-6 in bone marrow cultures. RAP had no effect on osteoclast differentiation in RANKL-treated RAW264.7 cells. Conclusion: These observations indicate that PAR-2 activation inhibits osteoclast differentiation by acting on cells of the osteoblast lineage to modulate multiple mediators of the effects of PTH, 1,25(OH)2D3, and IL-11. Therefore, the role of PAR-2 in bone may be to protect it from uncontrolled resorption by limiting levels of osteoclast differentiation. [source] Osteoclast Inhibitory Peptide 2 Inhibits Osteoclast Formation via Its C-Terminal FragmentJOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2001Sun Jin Choi Abstract Osteoclast inhibitory peptide 2 (OIP-2) is a novel autocrine/paracrine factor produced by osteoclasts (OCLs) that inhibits bone resorption and OCL formation in vitro and in vivo. It is identical to the asparaginyl endopeptidase legumain. During maturation of OIP-2, a signal peptide and a 17-kDa C-terminal fragment (CTF) are cleaved to produce the mature enzyme. To determine if enzyme activity is required for inhibition of OCL formation or if only the CTF is responsible for these effects, we synthesized His-tagged complementary DNA (cDNA) constructs for the CTF of OIP-2, the proform of OIP-2, and the "mature enzyme" form of OIP-2. The proform or the CTF portion of OIP-2 inhibited OCL formation in a dose-dependent manner in murine bone marrow cultures stimulated with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. The mature form of OIP-2, which was enzymatically active, did not inhibit OCL formation. In addition, OIP-2 inhibited OCL formation in cultures of highly purified human OCL precursor cells or RAW264.7 cells stimulated with 10 ng/ml of receptor activator of NF-,B (RANK) ligand. Binding studies with His-tagged OIP-2 showed expression of a putative OIP-2 receptor on RAW264.7 cells treated with RANK ligand for 4 days and human marrow cultures treated with 1,25(OH)2D3 for 3 weeks. These data show that the CTF of OIP-2, rather than the mature enzyme, mediates the inhibitory effects of OIP-2 through a putative receptor on OCL precursors. [source] Capsular polysaccharide from Actinobacillus actinomycetemcomitans inhibits IL-6 and IL-8 production in human gingival fibroblastJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2003Yuko Ohguchi We previously reported that a capsular polysaccharide (CP) from Actinobacillus actinomycetemcomitans Y4 induces bone resorption in a mouse organ culture system and osteoclast formation in mouse bone marrow cultures. However, the effects of A. actinomycetemcomitans Y4 CP on human gingival fibroblasts (HGF) are still unclear. The present study was undertaken to test the hypothesis that A. actinomycetemcomitans Y4 CP alters the production of inflammatory cytokines, such as interleukin-6 (IL-6) and IL-8 by HGF. When HGF were cultured with various concentrations of Y4 CP for 24 h, IL-6 and IL-8 production decreased in a concentration-dependent manner. Y4 CP (100 ,g/ml) suppressed the release of IL-6 from 9.09 ± 0.08 ng/ml to 0.34 ± 0.21 ng/ml (P < 0.01) and IL-8 production decreased from 3.76 ± 0.03 ng/ml to 0.09 ± 0.01 ng/ml (P < 0.01). Y4 CP suppressed 70,80% of the release of IL-6 and IL-8 from HGF stimulated with Y4 lipopolysaccharide (LPS), too. Interestingly, anti- A. actinomycetemcomitans Y4 CP completely inhibited the effect of A. actinomycetemcomitans Y4 CP on IL-6 and IL-8 production from HGF. These results indicate that Y4 CP inhibits the release of IL-6 and IL-8 from HGF, suggesting that A. actinomycetemcomitans Y4 modulates the inflammatory response in periodontitis. Remarkably, this inhibitory effect was reversed by specific anti- A. actinomycetemcomitans Y4 CP suggesting an important relationship between the organism and the humoral host response. [source] Collagen barrier membranes decrease osteoclastogenesis in murine bone marrow culturesCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2010Hermann Agis Abstract Objective: Collagen barrier membranes (CBM) are used for guided bone regeneration to support the process of graft consolidation. It remains, unknown however, whether CBM can affect the consolidation of bone grafts by controlling the differentiation of progenitor cells into bone-resorbing osteoclasts and bone-forming osteoblasts. Material and Methods: To gain an insight into the underlying mechanisms, we performed in vitro bone marrow cultures on CBM (Bio-Gide®) under conditions that favor osteoclastogenesis and osteoblastogenesis, respectively. Measures of osteoclastogenesis were based on the number of tartrate-resistant acid-phosphatase-positive (TRAP+) multinucleated cells. Resorption assays revealed the activity of mature osteoclasts. Osteoblastogenesis was determined by alkaline-phosphatase activity. Viability was investigated utilizing the MTT assay. Results: Cultivation of murine bone marrow on CBM reduced the number of TRAP+ multinucleated cells compared with cultures on tissue culture plates. Inhibition of osteoclastogenesis was observed on the porous and the dense CBM surfaces. The majority of TRAP+ cells were mononucleated and the decreased osteoclastogenesis was not due to changes in cell viability. Furthermore, CBM are inert regarding the resorptive activity of mature osteoclasts. Moreover, osteoblastogenesis was not reduced when bone marrow cells were grown on the surface of CBM. Conclusions: These in vitro findings demonstrate that CBM can reduce the formation but not the activity of multinucleated osteoclasts. Our data further reveal that the formation of osteogenic cells from their progenitors is not reduced by the CBM. Overall, our results suggest that the beneficial effects of CBM during graft consolidation may involve their direct impact on osteoclastogenesis. To cite this article: Agis H, Magdalenko M, Stögerer K, Watzek G, Gruber R. Collagen barrier membranes decrease osteoclastogenesis in murine bone marrow cultures. Clin. Oral Impl. Res. 21, 2010; 656,661. doi: 10.1111/j.1600-0501.2009.01888.x [source] | ||||||||||