Bone Abstracts

Sp7 and Runx2 are essential transcription factors for osteoblast differentiation at an early stage, and Runx2 inhibits osteoblast maturation at a late stage. However, the functions of Sp7 in bone development are not fully elucidated. Thus, we pursued the functions of Sp7 in bone development by generating osteoblast-specific Sp7 transgenic (tg) mice using 2.3 kb Col1a1 promoter. Sp7 tg mice showed osteopenia and woven-bone like structure in the cortic...

We previously reported that interleukin (IL)-11 plays an important role in the mechanical stress and PTH-induced stimulation of osteoblast differentiation and bone formation. Mechanical stress and PTH enhance IL-11 gene promoter activity and increase IL-11 expression. Increased IL-11 down-regulates dikkopf 1/2 (Dkk1/2) expression and stimulates canonical Wnt signaling, which enhances osteoblast differentiation. The present study was undertaken to clarify the physiological role...

Smurf1 is an E3 ubiquitin ligase for Smad1/5, Runx2 and MEKK2 and plays a role as a negative regulator for osteoblast differentiation and bone formation. However, the role of Smurf1 in odontoblast differentiation has not been elucidated. Previously, we reported that histone deacetylase inhibitors (HDACi) enhance odontoblast differentiation through the upregulation of Nfic expression. In this study, we investigated the regulatory effect of HDACi on Smurf1 expression and the rol...

It is well known that the epidermal growth factor receptor (EGFR), its ligands, and the structurally related receptor ERBB2/neu are expressed in skeletal cells. However, the functions of EGFR ligands in bone cells remain poorly defined. In this study, we employed a transgenic mouse line overexpressing the EGFR ligand amphiregulin (AREG) specifically in osteoblasts under the α1(I)-collagen promoter. AREG-tg mice did not show changes in body weight or gross phenotype. Compa...

Collagen XIII is a conserved transmembrane collagen with wide distribution in various tissues. It can be enzymatically cleaved to form a soluble bioactive molecule with relevance to cell proliferation, migration and adhesion. Collagen XIII overexpression in mice causes a massive bone overgrowth with no defects in early skeletal development. The bone phenotype of Col13a1OE mice is most apparent in long tubular bones but also present in calvariae. Our findings show th...

We and others have recently showed that patients with type 2 diabetes mellitus (T2DM) have a higher risk for fracture, although they have normal or slightly higher bone mineral density (BMD). These findings suggest that bone fragility in T2DM, which is not defined by BMD, may contribute to fracture risk. Hyperglycemia accelerates the formation of advanced glycation end products (AGEs) and causes diabetic complications. AGEs including pentosidine are also known to cause bone fr...

Introduction: Mesenchymal stem cells (MSCs) counteract the decline of physiologic functions but their regenerative power decreases with age. In particular osteogenic differentiation capacity of MSCs has been shown to decrease with age thereby contributing to slowed down bone formation and osteoporosis. While much is known about cellular aging of MSCs, little is known about extrinsic factors influencing their functionality. Here we set out to identify circulating factors of the...

Proprotein convertase PC5/6 (Pcsk5) is expressed in mouse bone and Pcsk5 epiblast-specific conditional knockout mice have a bone phenotype displaying small size, delayed ossification and additional thoracic segments and ribs. Some features are attributed to growth and developmental factor 11 (GDF11) – a known substrate for PC5/6 – while the delayed mineralization has yet to be explained. Osteopontin (OPN) is a bone matrix protein with roles in miner...

Aging is a complex process that results in the decline of physiologic functions due to accumulation of damage in cells and tissues. Mesenchymal stem cells (MSCs) counteract this decline but their regeneration capacity decreases with age. In particular osteogenic differentiation potential of MSCs has been shown to decrease with age thereby contributing to slowed down bone formation and osteoporosis. While much is known about cellular aging of MSCs, little is known about factors...

Few drugs generate bone-stimulatory effects via epigenetic mechanisms. Modulation of CpG-residues hydroxymethylation in gene-promoters of key osteoblast-related factors (e.g., DLX5) induces their expression and increases osteoblast differentiation in vitro. The chemical properties of sulforaphane (SFN), a natural compound abundantly present in cruciferous vegetables like broccoli, suggest that it may have similar molecular and biological effects. Previous stu...

Type 2 diabetes mellitus impairs bone quality and increases fracture risk. We showed that diabetic ZDF rats have low bone mass due to impaired osteoblastogenesis, which can be partially reversed with an intermittent parathyroid hormone 1–84 (PTH) therapy. It remains unclear, why PTH treatment does not fully restore osteoblast (OB) function in diabetic conditions. Here, we tested if high glucose (HG) conditions lead to a partial PTH resistance in osteoblasts. Pre-osteoblas...

Mesenchymal cells alter and retain their phenotype during skeletal development through activation or suppression of signaling pathways. For example, we have shown that Wnt3a only stimulates osteoblast differentiation in cells with intrinsic osteogenic potential (e.g., MC3T3-E1 pre-osteoblasts) and not in fat cell precursors or fibroblasts (respectively, 3T3-L1 pre-adipocytes or NIH3T3 fibroblasts). Wnt3a promotes osteogenesis in part by stimulating autocrine production of the ...

Besides its well known effect on longitudinal bone growth, GH plays a role in the maintenance of adult bone mass. As aging progresses GH levels decline, bone mass decreases and mesenchymal precursors show a reduced osteogenic differentiation capacity resulting in an increase in bone marrow adipocytes. We investigated the effect of GH on MSC differentiation and the possible involvement of microRNA in this process. Human MSC derived from trabecular specimens, waste material of o...

BMPs and canonical Wnts are the representative developmental signals that enhance osteoblast differentiation and bone formation. Previously, we demonstrated that EGF inhibits BMP2-induced osteoblast differentiation through the induction of Smurf1 expression. However, the regulatory role of EGF in Wnt/β-catenin-induced osteoblast differentiation has not been elucidated. In this study, we investigated the effect of EGF on Wnt/β-catenin signaling-induced osteoblast diff...

Background: Autocrine and paracrine Wnt signaling operates in stem cell populations and regulates mesenchymal lineage specification. In Wnt producing cells, Wntless (GPR177) supports the transport of Wnt from the trans-Golgi network (TGN) to the cell surface in vesicles, from which Wnt is then released. The retromer complex (VPS35) interacts with Wntless and retrieves Wntless from endosomes back to TGN, thereby maintaining the normal levels of Wntless protein. V-ATPases-driven...

Changes in the ability of self-renewal and differentiation of mesenchymal stem cells may be affected by osteoporosis. The aim of this investigation was to compare the transcriptional profile of mRNAs and miRNAs of osteoblastic cells from calvaria and bone marrow of female rats after ovariectomy. Following the approval by ethics committee, 18 wistar rats were divided into control (sham) and ovariectomized groups. After 150 days, both groups were sacrificed to collect the femurs...

Allopurinol and, and its active metabolite, oxypurinol are widely used in the treatment of gout and hyperuricemia. They act by inhibiting xanthine oxidase an enzyme in the purine degradation pathway that converts xanthine to uric acid. This oxygen-dependent reaction also results in the generation of superoxide free radicals. The aim of this investigation was to examine the effect of allopurinol and oxypurinol on osteoblast differentiation and function. Rat calvarial osteoblast...

It is still unknown where from osteoblasts are recruited during remodeling of adult human cancellous bone. Still, it is often suggested that they originate from perivascular osteoprogenitors in the bone marrow (BM). Here we propose also the existence of a layer of osteoprogenitors at the periphery of the BM. This proposal is based on electron and light microscopy of the bone surface and of the neighboring BM in human iliac crest biopsies, where we quantified cell densities, ce...

Epidermal growth factor-like repeats and discoidin I-like domains 3 (Edil3) is an extracellular matrix protein that contains Arg-Gly-Asp (RGD) motif to bind to integrins. Recently it has been reported that Edil3 is involved in various biological processes, including angiogenesis and cellular differentiation. This study was to explore the role of Edil3 in osteoblast differentiation and an underlining molecular mechanism. When MC3T3E1 cells were cultured with osteogenic medium, ...

We investigated the ability of microRNAs to regulate osteoblast differentiation by controlling distinct aspects of the differentiation process. We have identified by microRNAs microarray a set of miRNAs that are differentially regulated during differentiation of the two osteoblast cell lines MC3T3-E1 and C3H10T1/2. We focused on miR-468 that is a potential regulator of Runx2.In our microarray analysis miR-468 was expressed at a high level and was strongl...

MicroRNAs are important regulators of gene expression with documented role in bone metabolism and osteoporosis. Moreover, the use of miRNAs constitutes potential therapeutic targets. Our aim was to identify miRNAs differentially expressed in fractured compared to healthy bone. Additionally, we performed a miRNA profiling of primary osteoblasts to assess the origin of the differentially expressed miRNAs. Total RNA was extracted from fresh femoral neck trabecular bone from women...

BAG-1 interacts with diverse proteins including heat shock proteins (HSC70/ HSP70) and nuclear hormone receptors to modulate cell proliferation, differentiation and apoptosis. We have shown that bone marrow stromal cells (BMSCs) of Bag-1+/− female mice display reduced BMP-2-directed osteogenic differentiation potential. Estradiol binds to estrogen receptors (ERs) and is functionally involved in BMP-directed osteogenic differentiation of osteoprogenito...

Objectives: A role for glucose-dependent insulinotropic polypeptide (GIP) in controlling extracellular bone matrix deposition and maturation has previously been evidenced in GIP receptor knock-out mice. However, as the GIP receptor is expressed in several tissues other than bone it was difficult to ascertain whether the modifications of extracellular bone matrix were due to direct effects on osteoblasts or indirect through regulation of signals originating from other tissues. ...

Small GTPases of the Rho family (RhoA and Rac-1) are responsible for cytoskeleton dynamics (particularly actin polymerisation) and control cellular tension. For these reasons, they are implicated in the commitment of multipotent cells (MCs). In one hand, increased tension (important RhoA activity) is commonly associated with osteogenesis (OS), in the other hand, a reduced one (low RhoA activity) is associated with adipogenesis (AD). Nevertheless, precise RhoGTPases regulations...

Uncarboxylated osteocalcin, allegedly via G-protein coupled receptors, interacts with adipocytes and pancreatic β-cells, thus affecting metabolic homeostasis. Here, we demonstrate that MK-7 directly and indirectly, via osteocalcin, modulates the endocrine functions of both β-cells and adipocytes.• It was shown (by applying the Mir@nt@n-based emulation algorithm) that MK-7 was involved in a network of intracellular regulat...

Little is known about the molecular mechanisms underlying the interaction between Sclerostin (SOST) and estrogen, showing an inverse relation in clinical data. Therefore, we investigated mechanisms by which estrogen modulates Sost expression at human osteoblastic cell level in association with BMP-2 signaling, which is a potential route of SOST induction. BMP-2 significantly induced SOST expression, which is suppressed by 17β-estradiol (E2) in human mesenchymal s...

Osteoporosis is generally accompanied by the fatty degeneration of the bone marrow. The enhanced deposition of adipocytes may result from adipogenic differentiation of bone-marrow mesenchymal stem cells (MSC) and from the adipogenic conversion of osteoblastic cells respectively. Thus, whether this clinical observation is a cause of the disease or rather a reaction of the afflicted bone marrow remains to be elucidated.Previous microarray and bioinformatic...

Background: Hypoxia induces mesenchymal stem cells (MSCs) proliferation but results in a population with impaired osteogenic differentiation potential. Bone healing of tibial lengthening is enhanced by hyperbaric oxygen therapy. However, little is known about the effects of HBO on the Wnt signaling pathway in MSCs.Materials and methods: MSCs were cultured in complete medium and the osteogenic groups were cultured in osteogenic induction medium. Control c...

There is a similarity of the mechanisms of physiological and pathological mineralization. Pathological calcification of soft tissues as the case of vascular calcification is characterized by the deposition of hydroxyapaptite induced by matrix vesicles at least in the initial stage as in the case of physiological calcification in skeletal tissues. Lipid metabolism is involved in the differentiation of smooth muscle cells and bone cells suggesting that phospholipases can modulat...

Bone cells control initial steps of mineralization by forming matrix vesicles (MVs) in which calcium and phosphate ions are accumulated. Under physiological conditions, MVs are released to the extracellular matrix (ECM) and Ca2+ and Pi form hydroxyapatite (HA). Growing minerals break the MVs membrane and are deposited in ECM. Under pathological conditions the mineralization process becomes deregulated, which leads to the formation of calcium phosphate deposits. It is suggested...

The purpose of this study was evaluated the osteogenic differentiation in vitro of mesenchymal stem cells (MSC) of SHR (Spontaneously Hypertensive Rats) and Wistar (Normotensive) rats.Therefore, MSC from femoral bone marrow of Wistar and SHR rats 4 weeks old were utilized. The experimental protocols were approved by the Animal Experiments Local Ethics Committee (Process 00716-2012). The osteogenic medium (OM) consist of the proliferation medium (MEM) supplemented with...

Improving the effectiveness of adipose-derived human mesenchymal stromal/stem cells (AMSCs) for skeletal therapies requires a detailed molecular characterization of mechanisms supporting cell proliferation and multi-potency of AMSCs. We compared gene expression data obtained by high-throughput RNA sequencing and RT-qPCR of actively proliferating and uninduced post-proliferative AMSCs with flow cytometry data for mesenchymal stem cell markers (e.g., CD44, CD73/NT5E, CD90/THY1 a...

Titanium implants have been extensively used in dentistry as a replacement of absent dental elements. The biocompatibility of a material depends on cellular response in contact with a surface. The microarray technology is a tool to obtain an overview of the cell state in terms of large-scale transcriptional expression in different situations. Thus, the objective of this investigation was to evaluate the transcriptional profile of osteoblastic cells from human alveolar bone cul...

IGF1 is an osteo-anabolic factor that stimulates osteogenic precursor cell differentiation. IGF1 is produced in bone in response to mechanical stimulation, but also in mechanically-stimulated muscle cells. IGF1 enhances the rate of mRNA translation in muscle cells via activation of the PI3K/AKT/mTOR pathway, thereby increasing in muscle mass. Therefore we hypothesized that IGF1 not just enhances osteogenic differentiation of precursors, but also stimulates protein syn...

Caffeine is a methylxanthine found in many foods and is widely consumed by the human population. Therefore, its effects and mechanisms in various tissues have been widely studied. Various bone abnormalities have been observed in fetuses from rats treated with caffeine. But the genesis of these abnormalities is not known. The objective of this study was to verify the metabolism and activity of calvaria osteoblasts from offspring of rats treated with caffeine during pregnancy. T...

The lactation has been considered a cause of bone loss in humans and animals. Studies have shown that during lactation, there is a significant reduction of bone mineral density. Rats at the end of lactation show reduced bone mass. The objective of this study was to verify the effect of lactation under osteogenic potential of bone marrow mesenchymal stem cells (BMMSCs) of female rats. Twelve Wistar rats were distributed among the control and lactating groups. The experiment was...

Collagen barrier membranes are used in guided tissue regeneration to support bone healing and periodontal regeneration. Pharmacological inhibitors of prolyl-hydroxylases (PHD) can support hard and soft tissue regeneration and are therefore a promising tool for periodontal therapy. Here we evaluate the release kinetic of the PHD inhibitors dimethyloxaloylglycine and L-mimosine from the collagen barrier membranes.The PHD inhibitors were lyophilized onto co...

Up to now, most of standard methods for measuring inorganic phosphate (Pi) to determine phosphatase activity are based on coupled enzyme assays, colorimetric methods or conductance measurements. However, none of these methods can measure Pi, substrate and protein concentrations simultaneously, allowing direct kinetic determinations of phosphatase activity in cells in a single assay. Among the enzymes having a pyrophosphatase activity and releasing Pi...

This study was performed to characterize the effects of calcium phosphate coated and hydroxyapatite coated zirconia compared to smooth surfaced zirconia with bone marrow-derived osteoblast culture.Bone marrow-derived osteoblasts were cultured on i) smooth zirconia, ii) zirconia coated with calcium phosphate (CaP), and iii) zirconia coated with hydroxyapatite (HA). The tetrazolium-based colorimetric assay (MTT test) was used for examining the attachment o...

After trauma or carious lesion dental pulp healing is difficult to predict. In addition systemic diseases like diabetes mellitus can impair the regenerative capacity. New regenerative strategies target prolyl hydroxylase (PHD) by pharmacological inhibitors to stimulate hard and soft tissue healing. PHD inhibitors such as L-mimosine (L-MIM) induce vascular endothelial growth factor (VEGF) production by promoting angiogenesis. However, it is unclear if L-MIM is a feasible tool t...

Nacre, or mother of pearl, is a promising natural biocompatible biomaterial consisting of aragonite (97%) and of organics (3%) and capable to increase the cell osteogenic activity. It has been established that osteoarthritic osteoblasts present a mineralization defect and, to date, only a few molecules (vitamin D3 and bone morphogenetic protein2) could improve the mineralization potential of this cell type. In this context, we evaluated the impact of nacreous molecules on the ...

Strontium ranelate is a promising drug used in the treatment of osteoporosis. This drug has a unique dual effect on bone turnover, simultaneously increasing bone formation by osteoblasts (anabolic effect) and decreasing bone resorption by osteoclasts (antiresorptive effect). The goal of this study was to evaluate: i) anabolic effects of strontium ranelate on the formation of bone-like mineralized matrix in osteoblast cell cultures and ii) changes the drug could cause on the ma...

The integration of biomaterials into the calcified bone tissue is essential for the clinical success of bone implants. A particular strategy to improve such integration is the use of specific molecules to increase osteoblast cell adhesion, proliferation, and/or differentiation on the surface of the implants, aiming to enhance the interaction of cells with biomaterials. The goal of this study was to better understand the potential of the anti-osteoporotic drug strontium ranelat...

Constant remodeling of extracellular matrix is a hallmark during physiological conditions, such as stem cell differentiation, embryogenesis and tissue repair. Matrix metalloproteinases (MMP) play a key role in these processes. Mesenchymal stem cells derived from dental pulp are multipotent and have the capacity to differentiate into mesenchymal lineages. Bone morphogenetic proteins (BMP) are a family of signaling molecules critically involved at various stages in the formation...

Brain-derived neurotrophic factor (BDNF) has recently emerged as a factor able to concurrently target age related diseases as neurodegenerative disease, osteoporosis and metabolic syndrome. However the role of BDNF in the frailty syndrome associated with aging has never been investigated. The deletion of central BDNF gene in mice results in increased bone mass and in vitro experiments show that BDNF has a positive effect on bone. BDNF expression is mediated by estroge...

The molecular mechanisms underlying telomere shortening and telomerase deficiency contributing to defective age-related bone formation are poorly studied. We have previously demonstrated the role of telomerase re-activation in enhancing osteoblast differentiation of BMSCs in vitro and in vivo. Here, we investigated further the signaling pathways underlying the regulatory function of telomerase in osteogenesis. Comparative microarray analysis of telomerase-ove...

Protein kinases are an important class of regulatory elements and pharmacological targets for treatment of a number of diseases including cancer, heart and lung diseases. However, their role in regulation of the skeletal (mesenchymal) stem cell (MSC) functions and bone formation is not fully understood. Thus, we performed functional screening of human kinome, using three siRNAs for each of the ~700 known kinases represented in the human genome. Activity of alkaline phosphatase...

Wnt factors bind to heparan sulfate chains of syndecans that hence control their distribution in the cell microenvironment and also contribute to the internalization and recycling of the Wnt receptors. Syndecans are therefore likely important Wnt regulators within the bone marrow. Here, we investigated the interactions between Syndecan-2 and Wnt signaling in normal bone cells. We analyzed the effects of 2.3 kb Col1A1 promoter-driven Syndecan-2 overexpression in osteoblasts. Sy...