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Villeurbanne, France

Monfoulet L.-E.,University of Paris Pantheon Sorbonne | Becquart P.,University of Paris Pantheon Sorbonne | Marchat D.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP | Vandamme K.,University of Paris Pantheon Sorbonne | And 7 more authors.
Tissue Engineering - Part A | Year: 2014

The present study aimed at elucidating the effect of local pH in the extracellular microenvironment of tissue-engineered (TE) constructs on bone cell functions pertinent to new tissue formation. To this aim, we evaluated the osteogenicity process associated with bone constructs prepared from human Bone marrow-derived mesenchymal stem cells (hBMSC) combined with 45S5 bioactive glass (BG), a material that induces alkalinization of the external medium. The pH measured in cell-containing BG constructs was around 8.0, that is, 0.5U more alkaline than that in two other cell-containing materials (hydroxyapatite/ tricalcium phosphate [HA/TCP] and coral) constructs tested. When implanted ectopically in mice, there was no de novo bone tissue in the BG cell-containing constructs, in contrast to results obtained with either HA/TCP or coral ceramics, which consistently promoted the formation of ectopic bone. In addition, the implanted 50:50 composites of both HA/TCP:BG and coral:BG constructs, which displayed a pH of around 7.8, promoted 20-30-fold less amount of bone tissue. Interestingly, hBMSC viability in BG constructs was not affected compared with the other two types of material constructs tested both in vitro and in vivo. Osteogenic differentiation (specifically, the alkaline phosphatase [ALP] activity and gene expression of RUNX2, ALP, and BSP) was not affected when hBMSC were maintained in moderate alkaline pH (≤7.90) external milieu in vitro, but was dramatically inhibited at higher pH values. The formation of mineralized nodules in the extracellular matrix of hBMSC was fully inhibited at alkaline (>7.54) pH values. Most importantly, there is a pH range (specifically, 7.9-8.27) at which hBMSC proliferation was not affected, but the osteogenic differentiation of these cells was inhibited. Altogether, these findings provided evidence that excessive alkalinization in the microenvironment of TE constructs (resulting, for example, from material degradation) affects adversely the osteogenic differentiation of osteoprogenitor cells. © Copyright 2014, Mary Ann Liebert, Inc. 2014. Source

Magallanes-Perdomo M.,University of Lyon | Magallanes-Perdomo M.,INSA Lyon | Meille S.,University of Lyon | Meille S.,INSA Lyon | And 5 more authors.
Journal of the European Ceramic Society | Year: 2012

A discussion of the effects of Bioglass ® powder crystallisation on the in vitro bioactivity in simulated body fluid (SBF) is presented. Starting from Bioglass ® powder, different glass-ceramics were obtained by thermal treatments between 580°C and 800°C, with variable crystallisation content (from 10 to 92wt%). All samples (glass and glass-ceramics) showed apatite formation at their surface when immersed in SBF. In case of the glass and the samples with lowest crystallinity, the first step of apatite formation involved a homogenous dissolution followed by an amorphous calcium phosphate (CaP) layer precipitation. For the samples with a high crystallisation content, heterogeneous dissolution occurred. For the first time, the Stevels number of the amorphous phase is used to explain the possible dissolution of the crystalline phase present in materials with a similar chemical composition of the Bioglass ®. All samples presented at 21 days of immersion in SBF B-type hydroxycarbonate apatite crystals. © 2012 Elsevier Ltd. Source

Monfoulet L.,University of Paris Pantheon Sorbonne | Deschepper M.,University of Paris Pantheon Sorbonne | Vandamme K.,University of Paris Pantheon Sorbonne | Manassero M.,University of Paris Pantheon Sorbonne | And 8 more authors.
IRBM | Year: 2012

The limitations imposed to both autogenous and allogenous bone grafts led to the development of new strategies for the treatment of large bone defects. The approach of bone tissue engineering aims to restore damaged bone tissue by combining osteocompetent cells such as mesenchymal stromal cells (MSC), and material scaffolds like ceramics. However, the therapeutic effectiveness of cell constructs has not yet met that of autologous bone grafts, in part due to the high death rate of cells (loaded onto the material scaffold) upon their implantation into the injured site. In order to improve the therapeutic functionality of these cell constructs, different strategies can be implemented. In this context, the Glassbone project aimed to optimize the conditions for preparation of tissue engineered products by approaching three aspects: identification of optimal ceramic scaffold relevant to bone formation; survival of implanted cells post-implantation, and finally cell preconditioning to promote cell viability in vivo. Such project will pave the way for the development of new "pro-survival" tissue engineered materials for optimal tissue regeneration. © 2012 Elsevier Masson SAS. All rights reserved. Source

Nathalie G.,CNRS Laboratory for Materials: Engineering and Science | Jerome C.,CNRS Laboratory for Materials: Engineering and Science | Marc C.J.,CNRS Laboratory for Materials: Engineering and Science | Sylvain M.,CNRS Laboratory for Materials: Engineering and Science | And 2 more authors.
Ceramic Engineering and Science Proceedings | Year: 2010

The present study aims to characterize a composite made of poly-L,DL-lactic acid (P(L,DL)LA, Mv: 120 KDa) containing 30 wt% of 45S5 bioactive glass particles. Glass transition (around 52°C) of the polymer was assessed by differential scanning calorimetry (DSC). The mechanical properties of the neat polymer and the composite were evaluated by tensile and compressive tests. From these tests, it was confirmed that the addition of bioglass into the polymer matrix leads to a slight decrease in tensile strength and an increase in elastic modulus. In vitro bioactivity of this composite was evaluated by immersion in a simulated body fluid (SBF) at 37°C for different durations. Formation of hydroxyapatite crystals on the surface of the composite was recorded by scanning electron microscopy and confirmed by X-ray diffraction. Many hydroxyapatite crystals covered the surface of the composite after 14 days of immersion in simulated body fluid. Osteoblast cells MG-63 (human osteosarcoma cell line) were cultured in direct contact with the polymer and the composite. Cells morphology and attachment were analysed using SEM and MTT viability test. Scanning electron microscopy analysis showed the presence of cells at the surface of the composite. These results confirmed the biocompatibility of the composite and the positive effect of the bioglass on the osteoblast cells adhesion and proliferation on the composite. Source

Ginsac N.,University Claude Bernard Lyon 1 | Ginsac N.,INSA Lyon | Chenal J.-M.,University Claude Bernard Lyon 1 | Chenal J.-M.,INSA Lyon | And 7 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2011

We report on the crystallization processes occurring at the surface of PDLLA-Bioglass® composites immersed in simulated body fluid. Composites manufactured by injection molding and containing different amounts (0, 20, 30, and 50 wt %) of 45S5 Bioglass® particles were tested for durations up to 56 days and compared with Bioglass® particles alone. Crystallization processes were followed by visual inspection, X-ray diffraction (with Rietveld analysis) and scanning electron microscopy. Both calcite and hydroxyapatite were formed at the surface of all materials, but their relative ratio was dependent on the Bioglass® content and immersion time. Hydroxyapatite was always the major phase after sufficient immersion time, insuring bioactivity of such composites especially for Bioglass® content higher than 30 wt %. A scenario of crystallization is proposed. Rapid degradation of the composites with 50 wt % was also observed during immersion. Therefore, composites with 30 wt % of Bioglass® particles seem to exhibit the best balance between bioactivity and stability at least during the first weeks of immersion in contact with body fluids. Copyright © 2011 Wiley Periodicals, Inc. Source

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