Phosphorylated and Non-phosphorylated Leucine Rich Amelogenin Peptide Differentially Affect Ameloblast Mineralization

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Teaching and performing audits on caesarean delivery reduce the caesarean delivery rate.

AIM:To assess the factors associated with lower rate of caesarean deliveries in the South of France, based on the characteristics and organisation of the region's 40 maternity facilities and the characteristics of the practitioners in these facilities. METHOD:A retrospective study from 1 January 2012 to 31 December 2015. Data were collected by the Mediterranean network and a declarative survey was completed by each maternity facility in the region to study factor which could be associated with lower caesarean rate by univariate and multivariate analysis. RESULTS:250 564 women gave birth during this period, of which 55 097 by caesarean section. The mean caesarean delivery rate over the four years was 22.0%. The rate was significantly higher in private maternity facilities [23.9% (21.9%- 25.8%), p<0.05] and type III (maximum care level) maternity facilities [24.2% (21.3%- 27.1%), p<0.05]. After a stepwise regression, the factors associated with a decrease in the caesarean delivery rate were audits concerning caesarean delivery (19.83%, β = - 2.48, p = 0.03 over the four years) and the provision of training to trainee doctors at the maternity facility (20.28%, β = - 1.08, p = 0.04 over the four years). CONCLUSION:Performing audits in relation to caesarean deliveries could affect the caesarean. Teaching trainee doctors could be an indicator of quality of caesarean practices. They should be encouraged in maternity facilities to reduce the rate of caesareans

NAMPT expression in osteoblasts controls osteoclast recruitment in alveolar bone remodeling

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Strategies Developed to Induce, Direct, and Potentiate Bone Healing

Bone exhibits a great ability for endogenous self-healing. Nevertheless, impaired bone regeneration and healing is on the rise due to population aging, increasing incidence of bone trauma and the clinical need for the development of alternative options to autologous bone grafts. Current strategies, including several biomolecules, cellular therapies, biomaterials, and different permutations of these, are now developed to facilitate the vascularization and the engraftment of the constructs, to recreate ultimately a bone tissue with the same properties and characteristics of the native bone. In this review, we browse the existing strategies that are currently developed, using biomolecules, cells and biomaterials, to induce, direct and potentiate bone healing after injury and further discuss the biological processes associated with this repair

Phosphorylated and Non-phosphorylated Leucine Rich Amelogenin Peptide Differentially Affect Ameloblast Mineralization

The Leucine Rich Amelogenin Peptide (LRAP) is a product of alternative splicing of the amelogenin gene. As full length amelogenin, LRAP has been shown, in precipitation experiments, to regulate hydroxyapatite (HAP) crystal formation depending on its phosphorylation status. However, very few studies have questioned the impact of its phosphorylation status on enamel mineralization in biological models. Therefore, we have analyzed the effect of phosphorylated (+P) or non-phosphorylated (−P) LRAP on enamel formation in ameloblast-like cell lines and ex vivo cultures of murine postnatal day 1 molar germs. To this end, the mineral formed was analyzed by micro-computed tomography, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, Selected Area Electon Diffraction imaging. Amelogenin gene transcription was evaluated by qPCR analysis. Our data show that, in both cells and germ cultures, LRAP is able to induce an up-regulation of amelogenin transcription independently of its phosphorylation status. Mineral formation is promoted by LRAP(+P) in all models, while LRAP(–P) essentially affects HAP crystal formation through an increase in crystal length and organization in ameloblast-like cells. Altogether, these data suggest a differential effect of LRAP depending on its phosphorylation status and on the ameloblast stage at the time of treatment. Therefore, LRAP isoforms can be envisioned as potential candidates for treatment of enamel lesions or defects and their action should be further evaluated in pathological models

Bioactive Glass/Polycaprolactone Hybrid with a Dual Cortical/Trabecular Structure for Bone Regeneration

International audienceOrganic-inorganic hybrid biomaterials stand as a promise for combining bone bonding and bone mineral-forming ability, stimulation of osteogenic cells, and adequate mechanical properties. Bioactive glass (BG)-polycaprolactone (PCL) hybrids are of special interest as they gather the ability of BG to enhance osteoblast-mediated bone formation with the slow degradation rate and the toughness of PCL. In this study, BG-PCL hybrids were synthesized in the form of scaffold, owing to a dual cortical/trabecular structure mimicking the bone architecture. Their biological potential was evaluated both in vitro using rat primary osteoblasts (RPO) and in vivo in a mice model of critical-size calvarial defects. BG-PCL scaffolds were compared to Lubboc (BTB), a commercial purified bovine xenograft widely used in orthopedics and periodontal procedures and known for its efficiency. BG-PCL hybrids were found to facilitate RPO adhesion at their surface and to enhance RPO differentiation when compared to BTB. An in vivo micro-CT study demonstrates a higher bone ingrowth with BG-PCL scaffolds and a complete chemical conversion of the remaining BG-PCL after 3 months of implantation, while histological data show the vascularization of BG-PCL scaffolds and confirm the well-advanced bone regeneration with ongoing remodeling. Finally, we evidence the complete chemical conversion of the remaining BG-PCL into a bone-like mineral

Osteogenic Effect of Fisetin Doping in Bioactive Glass/Poly(caprolactone) Hybrid Scaffolds

International audienceTreating large bone defects or fragile patients may require enhancing the bone regeneration rate to overcome a weak contribution from the body. This work investigates the osteogenic potential of nutrient fisetin, a flavonoid found in fruits and vegetables, as a doping agent inside the structure of a SiO 2 − CaO bioactive glass−poly(caprolactone) (BG−PCL) hybrid scaffold. Embedded in the full mass of the BG− PCL hybrid during one-pot synthesis, we demonstrate fisetin to be delivered sustainably; the release follows a first-order kinetics with active fisetin concentration being delivered for more than 1 month (36 days). The biological effect of BG−PCL−fisetin-doped scaffolds (BG−PCL−Fis) has been highlighted by in vitro and in vivo studies. A positive impact is demonstrated on the adhesion and the differentiation of rat primary osteoblasts, without an adverse cytotoxic effect. Implantation in critical-size mouse calvaria defects shows bone remodeling characteristics and remarkable enhancement of bone regeneration for fisetin-doped scaffolds, with the regenerated bone volume being twofold that of nondoped scaffolds and fourfold that of a commercial trabecular bovine bone substitute. Such highly bioactive materials could stand as competitive alternative strategies involving biomaterials loaded with growth factors, the use of the latter being the subject of growing concerns

Effect of Hypoxia on Dental Pulp Mesenchymal Stem Cells in a Purpose of Tissue Engineering

International audienceDuring life, teeth are exposed to severe injuries (decay, traumatisms…), which can result in dental pulp necrosis. Creating a “pulp tissue equivalent” constitutes a promising therapeutic approach to replace the current invasive treatments. Dental pulp of deciduous teeth contains mesenchymal stem cells (SHEDs: Stem cells from Human Exfoliated Deciduous teeth), shown to have a high proliferation and differentiation potential. Our approach aims to assess the effect of severe hypoxia on these cells, mimicking the clinical conditions of the matrix implantation in the pulp space. 3D collagen matrices seeded with SHEDs (1.5 million of cells/ml) were cultivated under severe hypoxia (1% O2) during 3 days. Then, to mimic the kinetics of revascularization, the matrices were replaced in normoxic conditions (21% O2). Induced mRNA and protein modifications were studied by qPCR, ELISA, Western Blot and immunocytochemistry, at several time points. A transcriptomic analysis (DNA affymetrix chips “gene” type) of the samples was then performed at the time point with the highest VEGF mRNA expression. The capacity of SHEDs exposed to hypoxia to induce angiogenenis was then tested in a tubulogenesis model. Finally, SHEDs pretreated by hypoxia were induced toward osteogenic differentiation in 3D plastic compressed collagen matrix. Our data show that hypoxic conditions induce: 1) an increase of the transcription factor HIF‐1 alpha observed in the cell nucleus, 2) a x4 increase of VEGF mRNA expression at 24 h (qPCR), confirmed by ELISA analysis, 3) the up‐regulation of numerous genes activated by HIF‐1 alpha and involved in angiogenesis, apoptosis and glycolysis regulation. Furthermore, SHEDs pretreated by hypoxia enhanced capillary formation by endothelial cells. In parallel, osteogenic differentiation assay showed that pretreatment by hypoxia did not impair matrix mineralization by SHEDs, which was slightly enhanced.These cells are good candidate for tissue engineering approaches, in particular for treating damaged dental tissues

Combining sclerostin neutralization with tissue engineering: An improved strategy for craniofacial bone repair

International audienceScaffolds associated with different types of mesenchymal stromal stem cells (MSC) are extensively studied for the development of novel therapies for large bone defects. Moreover, monoclonal antibodies have been recently introduced for the treatment of cancer-associated bone loss and other skeletal pathologies. In particular, antibodies against sclerostin, a key player in bone remodeling regulation, have demonstrated a real benefit for treating osteoporosis but their contribution to bone tissue-engineering remains uncharted. Here, we show that combining implantation of dense collagen hydrogels hosting wild-type (WT) murine dental pulp stem cells (mDPSC) with weekly systemic injections of a sclerostin antibody (Scl-Ab) leads to increased bone regeneration within critical size calvarial defects performed in WT mice. Furthermore, we show that bone formation is equivalent in calvarial defects in WT mice implanted with Sost knockout (KO) mDPSC and in Sost KO mice, suggesting that the implantation of sclerostin-deficient MSC similarly promotes new bone formation than complete sclerostin deficiency. Altogether, our data demonstrate that an antibody-based therapy can potentialize tissue-engineering strategies for large craniofacial bone defects and urges the need to conduct research for antibody-enabled local inhibition of sclerostin