Processing–structure–property relations of chemically bonded phosphate ceramic composites

ABSTRACT: Mechanical properties and microstructures of a chemically bonded phosphate ceramic (CBPC) and its composite with 1⋅0 wt% graphite nanoplatelets (GNPs) reinforcement have been investigated. Microstructure was identified by using optical and scanning electron microscopes, X-ray tomography, and X-ray diffraction. In addition, weight loss of the resin at room temperature was studied. The microstructure characterization shows that CBPC is itself a composite with several crystalline (wollastonite and brushite) and amorphous phases. SEM and micro tomography show a homogeneous distribution of crystalline phases. Bending and compression strength of the CBPC was improved by reducing bubbles via preparation in vacuum

A new biphasic osteoinductive calcium composite material with a negative Zeta potential for bone augmentation

The aim of the present study was to analyze the osteogenic potential of a biphasic calcium composite material (BCC) with a negative surface charge for maxillary sinus floor augmentation. In a 61 year old patient, the BCC material was used in a bilateral sinus floor augmentation procedure. Six months postoperative, a bone sample was taken from the augmented regions before two titanium implants were inserted at each side. We analyzed bone neoformation by histology, bone density by computed tomography, and measured the activity of voltage-activated calcium currents of osteoblasts and surface charge effects. Control orthopantomograms were carried out five months after implant insertion. The BCC was biocompatible and replaced by new mineralized bone after being resorbed completely. The material demonstrated a negative surface charge (negative Zeta potential) which was found to be favorable for bone regeneration and osseointegration of dental implants

Matériaux multiphasés pour l'ingéniérie tissulaire osseuse

Les affections ostéo-articulaires touchent des millions de personnes dans le monde et ce nombre augmente avec le vieillissement de la population. Les autogreffes et les allogreffes osseuses demeurent des matériaux de prédilection dans le traitement des pertes du tissu osseux. Parmi les substituts synthétiques, les biocéramiques phosphocalciques sont les plus utilisés grâce à leurs propriétés de bioactivité et d'ostéoconduction. Bien qu'elles ne soient pas généralement reconnues comme ostéoinductrices, notre étude a montré que l'implantation ectopique de granules de céramique conduit à la formation d'un tissu osseux. Nous avons ensuite étudié les applications de cette biocéramique en ingénierie tissulaire osseuse. Notre première approche a été d'associer ce matériau avec une matrice extracellulaire, la fibrine, en présence ou non de moelle osseuse. L'étude des propriétés de ce biomatériau composite/hybride a montré des caractéristiques ultra structurales, mécaniques et biologiques optimales pour des applications d'ingénierie tissulaire osseuse. Ces matériaux possèdent également des propriétés biologiques permettant la régénération et la formation du tissu osseux. Dans une seconde approche, le comportement de cellules de moelle osseuse ensemencées sur la matrice phosphocalcique a été analysé. Ces études ont permis de souligner la complexité des interactions cellules/matériaux en ingénierie tissulaire osseuse. L'ensemble de ce travail a montré le potentiel biologique des matériaux multiphasés pour des applications de reconstruction de défauts osseux.Millions people worldwide suffer from osteoarticular diseases and this number is increasing with the ageing of the population. Bone autografts and allografts remain the most employed materials for filling bone defects. Among synthetic bone substitutes, calcium phosphate bioceramics are widely used due to their bioactivity and osteoconductive properties. Although bioceramics are not generally recognized as osteoinductive, our study shows that ectopic implantation of ceramic granules led to the formation of mineralized bone tissue. Applications of this bioceramic in bone tissue engineering were studied. Our first approach associated this material with an extracellular matrix, the fibrin, with or without addition of bone marrow. Study of this composite/hybrid bone substitute properties have shown optimal ultra structural, mechanical and biological properties for bone tissue engineering. These materials also exhibited biological properties allowing bone tissue regeneration and formation. In a second approach, bone marrow cells were seeded onto calcium phosphate matrix. These studies have shown the complexity of cells/materials interactions in bone tissue engineering. The overall work demonstrated the biological potential of multiphasic materials for applications in bone tissue reconstruction.NANTES-BU Médecine pharmacie (441092101) / SudocNANTES-Bib.Odontologie (441092219) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

3D printed polymer–mineral composite biomaterials for bone tissue engineering: Fabrication and characterization

Applications in additive manufacturing technologies for bone tissue engineering applications requires the development of new biomaterials formulations. Different three-dimensional (3D) printing technologies can be used and polymers are commonly employed to fabricate 3D printed bone scaffolds. However, these materials used alone do not possess an effective osteopromotive potential for bone regeneration. A growing number of studies report the combination of polymers with minerals in order to improve their bioactivity. This review exposes the state-of-the-art of existing 3D printed composite biomaterials combining polymers and minerals for bone tissue engineering. Characterization techniques to assess scaffold properties are also discussed. Several parameters must be considered to fabricate a 3D printed material for bone repair (3D printing method, type of polymer/mineral combination and ratio) because all of them affect final properties of the material. Each polymer and mineral has its own advantages and drawbacks and numerous composites are described in the literature. Each component of these composite materials brings specific properties and their combination can improve the biological integration of the 3D printed scaffold. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2579-2595, 2019

Hybrid composites of calcium phosphate granules, fibrin glue, and bone marrow for skeletal repair.

Synthetic bone substitutes, such as calcium phosphate ceramics, give good results in clinical applications. In order to adapt to surgical sites, bioceramics come in the form of blocks or granules, and are either dense or porous. Combining these bioceramics with fibrin glue provides a mouldable and self-hardening composite biomaterial with the biochemical properties of each component. Critical-sized defects in the femoral condyle of rabbits were filled with TricOs/fibrin glue/bone marrow hybrid/composite material. The TricOs granules (1-2 mm) were composed of hydroxyapatite and beta tricalcium phosphate (60/40 in weight). The fibrin glue was composed of fibrinogen, thrombin and other biological factors and mixed with MBCP granules either simultaneously or sequentially. Bone marrow was also added to the MBCP/fibrin composite prior to filling the defects. After 3, 6, 12, and 24 weeks of implantation, the newly-formed bone was analysed with histology, histomorphometry and mechanical tests. The newly-formed bone had grown centripetally. Simultaneous application of fibrin glue showed better results for mechanical properties than sequential application after 6 weeks. Around 40% of bone had formed after 24 weeks in the three groups. Although the addition of bone marrow did not improve bone formation, the MBCP/fibrin material could be used in clinical bone filling applications

Micro-architecture of calcium phosphate granules and fibrin glue composites for bone tissue engineering.

International audienceCalcium phosphate ceramics are currently used as bone graft substitutes in various types of clinical applications. Fibrin glue is also used in surgery due to its haemostatic, chemotactic and mitogenic properties. By combining these two biomaterials, new composite scaffolds were prepared. In this study, we attempt to analyse whether thrombin concentration in the fibrin glue could influence the properties of the composite. The association between fibrin glue and calcium phosphate ceramic granules was characterized at the ultra structural level. Micro and macroporous biphasic calcium phosphate ceramic granules with a diameter of 1-2mm composed of hydroxyapatite and beta-tricalcium phosphate (60/40) were associated to fibrin glue. The composites were observed by scanning and transmission electron microscopy and microcomputed tomography. Fibre thickness, porosity and homogeneity of the fibrin clot were modified by increased the thrombin concentration. Mixing fibrin glue with calcium phosphate granules (1:2) did not modify the microstructure of the fibrin clot in the composite. Nevertheless, thrombin interacted with the bioceramic by inducing the nucleation of crystalline precipitate at the ceramic/fibrin glue interface. Combining fibrin sealant and calcium phosphate ceramics could lead to new scaffolds for bone tissue engineering with the synergy of the properties of the two biomaterials

Moderate excess of pyruvate augments osteoclastogenesis

Summary Cell differentiation leads to adaptive changes in energy metabolism. Conversely, hyperglycemia induces malfunction of many body systems, including bone, suggesting that energy metabolism reciprocally affects cell differentiation. We investigated how the differentiation of bone-resorbing osteoclasts, large polykaryons formed through fusion and growth of cells of monocytic origin, is affected by excess of energy substrate pyruvate and how energy metabolism changes during osteoclast differentiation. Surprisingly, small increases in pyruvate (1–2 mM above basal levels) augmented osteoclastogenesis in vitro and in vivo, while larger increases were not effective in vitro. Osteoclast differentiation increased cell mitochondrial activity and ATP levels, which were further augmented in energy-rich conditions. Conversely, the inhibition of respiration significantly reduced osteoclast number and size. AMP-activated protein kinase (AMPK) acts as a metabolic sensor, which is inhibited in energy-rich conditions. We found that osteoclast differentiation was associated with an increase in AMPK levels and a change in AMPK isoform composition. Increased osteoclast size induced by pyruvate (1 mM above basal levels) was prevented in the presence of AMPK activator 5-amino-4-imidazole carboxamide ribonucleotide (AICAR). In keeping, inhibition of AMPK using dorsomorphin or siRNA to AMPKγ increased osteoclast size in control cultures to the level observed in the presence of pyruvate. Thus, we have found that a moderate excess of pyruvate enhances osteoclastogenesis, and that AMPK acts to tailor osteoclastogenesis to a cell's bioenergetics capacity