MMP-2, MMP-9 and their inhibitors TIMP-2 and TIMP-1 production by human monocytes in vitro in the presence of different forms of hydroxyapatite particles.

DOI : 10.1016/j.biomaterials.2003.09.034After calcium-phosphates biomaterials based implantation like hydroxyapatite (HA) coating, particles are released in the periprosthetic tissues. Wear-debris induced fibrous membranes contain macrophage subsets that can produce metalloproteinases (MMPs), which are considered to be key enzymes in extra-cellular matrix turnover. Tissue inhibitors of metalloproteinases (TIMPs) are important regulator of MMPs activity. Interleukin-1 mainly produced by monocytes can also regulate MMPs production. In the present work, we have evaluated the effect of HA particles characteristics (size, shape and sintering temperature) on the MMP-2, -9 and their respective inhibitors TIMP-2, -1 production. Our results demonstrate that sintering temperature (that modify crystal size and surface area) have little effect on MMPs and TIMPs production. Non-phagocytable particles induced more MMP-9, although phagocytable particles induced more IL-1β release. The shape of the particles was the most important factor since needle-shaped particles induced the most significant up-regulated expression of MMPs and IL-1β

STEM and EDXS characterisation of physico-chemical reactions at the periphery of sol-gel derived Zn-substituted hydroxyapatites during interactions with biological fluids

With its good properties of biocompatibility and bioactivity hydroxyapatite (HA) is highly used as bone substitutes and as coatings on metallic prostheses. In order to improve bioactive properties of HA we have elaborated Zn2+ doped hydroxyapatite. Zn2+ ions substitute for Ca2+ cations in the HA structure and four Zn concentrations (Zn/Zn+Ca) were prepared 0.5, 1, 2, 5 % at. To study physico-chemical reactions at the materials periphery, we immersed the bioceramics into biological fluids for delays from 1 day to 20 days. The surface changes were studied at the nanometer scale by scanning transmission electron microscopy associated to energy dispersive X-ray spectroscopy. After 20 days of immersion we observed the formation of a calcium-phosphate layer at the periphery of the HA doped with 5% of zinc. This layer contains magnesium and its thickness was around 200 nm. Formation of this Ca-P-Mg layer represents bioactivity properties of the 5% Zn-substituted hydroxyapatite. This biologically active layer improves properties of HA and will permit a chemical bond between the ceramic and bone

Les dentinogenèses imparfaites

REIMS-BU Santé (514542104) / SudocPARIS-BIUM (751062103) / SudocLILLE2-UFR Odontologie (593502202) / SudocSudocFranceF

L'histoire de l'art dentaire vue à travers l'iconographie picturale et graphique de l'Antiquité à nos jours

LILLE2-UFR Odontologie (593502202) / SudocREIMS-BU Santé (514542104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Activités biologiques d'un peptide et mise au point d'un système de libération prolongée par microcapsulation en vue de la foctionnalisation de biomatériaux

La @première partie de ce travail a consisté en l'étude des effets d'un activateur du TGF-beta. Ce peptide KRFK, issu de la TSP-1, semble conserver ses propriétés activatrices du TGF-beta latent dans le système ostéoblastique.La deuxième partie de ce travail a concerné l'élaboration et la validation d'un système de libération prolongée, puis son association avec un revêtement prothétique. Ce système de libération est constitué de microcapsules. Leur caractérisation approfondie a permis de démontrer leur parfaite biocompatibilité, ainsi que leur capacité à libérer de façon prolongée le peptide. De plus, l'association de ces microcapsules à un revêtement de CaP a pu être réalisée par l'intermédiaire d'un film d'alginate de calcium. Ainsi, nous avons pu obtenir un biomatériau implantable en site osseux, et dont la capacité à libérer de façon prolongée un peptide actif sur les cellules osteoblastiques pourrait permettre d'accélérer la régénération tissulaire. Ces données peuvent donc inaugurer un nouveau type de biomatériau basé sur une approche liant l'ingénierie tissulaire et la pharmacotechnie.@The first part of this work was to study the effects of an activator of the TGF-beta. This peptide named KRFK, conserved its activator properties of the TGF-beta in the osteoblast.The second part of this work was to prepare and characterise a sustained release system, and then associate it to a prosthetic coating. This sustained release is called microcapsules. Their characterization allowed us to demonstrate their perfect biocompatibility and to obtain a sustained release of the peptide. Moreover, we created an alginate film in order to associate the release system to a CaP coating.Thus, we obtain a new biomaterial for bone implantation which is able to release an active peptide. This will lead to improve the bone regeneration.REIMS-BU Santé (514542104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Influence d'un phosphate de calcium substitué en strontium sur la physiologie de l'ostéoblaste humain en culture et évaluation de son potentiel de réparation osseusse chez la souris

Les phosphates de calcium sont des biomatériaux couramment utilisés dans de nombreuses spécialités médicales. L'amélioration de ces biomatériaux vise à augmenter leur ostéointégration et leur bioactivité. Le strontium possédant d'intéressantes capacités de modification de la physiologie osseuse, l'incorporation de ce dernier au sein de phosphates de calcium par substitution ionique pourrait permettre un déplacement de la balance osseuse vers la formation osseuse.Notre travail a permis de démontrer la capacité des particules de phosphates de calcium substitués en strontium à augmenter la prolifération des ostéoblastes en culture et à modifier l'expression et la synthèse des principales protéines impliquées dans la physiologie osseuse (Collagène de type I, Serpine H1, métalloprotéinases matricielles 1 et 2, inhibiteurs tissulaires des MMPs). Par ailleurs, la poudre de phosphates de calcium ne contenant pas de strontium a entrainé une sécrétion accrue de chimiokines pro-inflammatoires (MCP-1 et GRO-?) qui n'a pas été observée pour la poudre substituée. Enfin, des études in-vivo réalisées dans un modèle de défaut osseux murin a permis de démontrer une plus grande résorbabilité de la poudre contenant du strontium et sa plus grande capacité à stimuler la réparation osseuse.Calcium phosphate are widely used in medicine. Their upgrade tend to enhance their biocompatibility and their bioactivity. Strontium has interesting capability to modify the bone physiologie. Its incorporation in calcium phosphates could lead to modify the bone balance toward osteogenesis.The present work reveal the capacities of such biomaterials to enhance the replication of osteoblasts ant to modify the expression and the synthesis of proteins implicated in the bone balance (type I collagen, serpinH1, Matrix metalloproteinases 1 and 2, tissular inhibitors of MMPs). Moreover, non substituted calcium phosphate powders enhance the expression and synthesis of inflammatory cytokines (MCP-1 and Gro-a). This fact was not observed with the non substituted powder. In-vivo studies on a mouse model permit us to demonstrate the higher resorbability and the higher bone healing capability of the substituted powder.REIMS-SCD-Bib. electronique (514549901) / SudocSudocFranceF

Comportement de cellules osseuses humaines en culture en présence du lipopeptide Ea-KRFK et au contact d'un revêtement phosphocalcique en vue de la fonctionnalisation de biomatériaux

L' @objectif de notre laboratoire est de conceptualiser des biomatériaux fonctionnalisés. La réalisation de ces biomatériaux se fait par adjonction d'un système de libération prolongée de peptides sur un revêtement de phosphate de calcium élaboré par électrodéposition. Le peptide utilisé dans cette étude est un lipopeptide composé d'acide élaïdique pour sa partie lipidique et du peptide KRFK, issu de la thrombospondine de type I. Ce lipopeptide a la capacité d'activer le TGF-bêta1 latent. Une fois activé, le TGF-bêta1 exerce des effets stimulateurs sur les ostéoblastes et la formation osseuse. Toutefois, ses effets varient selon le type cellulaire utilisé et la concentration de TGF-bêta1 utilisée notamment. Ainsi, la première partie de notre étude a consisté à étudier les effets du TGF-bêta1 sur la formation osseuse dans un modèle d'ostéoblastes humains en culture tout au long de leur cinétique de différenciation. Cette étude nous a permis de déterminer à quel moment de la cinétique de différenciation des ostéoblastes le lipopeptide doit être libéré du biomatériau pour aller activer le TGF-bêta1 latent présent dans la matrice osseuse. La deuxième partie de ce travail a permis de démontrer la capacité du lipopeptide élaïdyl-KRFK à activer le TGF-bêta1 latent dans les ostéoblastes humains. Et enfin la dernière partie du travail a mis en évidence la biocompatibilité du revêtement de phosphate de calcium élaboré par électrodéposition destiné à être utilisé pour la fonctionnalisation des matériaux. Ainsi nous avons montré que le lipopeptide est un bon candidat à l'encapsulation en vue d'une libération prolongée et que le revêtement était un bon matériau pour la fonctionnalisation.REIMS-BU Santé (514542104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Nestin expression in embryonic and adult human teeth under normal and pathological conditions.

Nestin is an intermediate filament most related to neurofilaments and expressed predominantly in the developing nervous system and muscles. In the present study we examined the in vivo distribution of nestin in human teeth during embryonic development and in permanent teeth under normal and pathological conditions. The results show that nestin is first expressed at the bell stage and that its distribution is restricted in pulpal cells located at the cusp area of the fetal teeth. In young permanent teeth, nestin is found only in functional odontoblasts, which produce the hard tissue matrix of dentin. Expression is progressively down-regulated and nestin is absent from older permanent teeth. In carious and injured teeth, nestin expression is up-regulated in a selective manner in odontoblasts surrounding the injury site, showing a link between tissue repair competence and nestin up-regulation under pathological conditions. In an in vitro assay system of human dental pulp explants, nestin is up-regulated after local application of bone morphogenic protein-4. A similar effect is seen in cultures of primary pulp cells during their differentiation into odontoblasts. Taken together, these results suggest that nestin plays a potential role in odontoblast differentiation during normal and pathological conditions and that bone morphogenic protein-4 is involved in nestin up-regulation

Sensitivity of bacterial biofilms and planktonic cells to a new antimicrobial agent, Oxsil 320N.

The effective concentrations of disinfectants were determined for planktonic bacteria using the norms EN 1040 and NF T 72-150. This concentration corresponds to biocide efficacy after 5 min of contact, followed by neutralization. However, micro-organisms often colonize a substratum and form microcolonies or biofilms where they are enclosed in exopolymer matrices. Biofilms are commonly resistant to a broad range of antimicrobial agents, and resistance mechanisms involve exopolymer matrices, changes in gene expression and metabolic alterations. Due to these different resistance mechanisms, it is difficult to select and titrate antimicrobial agents to be effective against biofilms. In this context, SODIFRA developed a new disinfectant, Oxsil 320N (French patent 94 15 193). Oxsil 320N is an association of three active principles: hydrogen peroxide, acetic acid/peracetic acid and silver. This biocide was tested on planktonic bacteria and on 24-h biofilms formed on AISI 304 stainless steel surfaces. The effective concentration of Oxsil 320N was also determined on biofilms using SODIFRA recommendations (without neutralization of the biocide). Data showed that the antimicrobial efficacy measured on planktonic bacteria is not a reliable indicator of performance when biofilm is present. When biofilms were exposed to Oxsil 320N, the concentration needed to achieve a 10(5)-fold decrease in concentration was 10 times higher than that for bacterial suspensions (0.313% Oxsil 320N). An effective concentration of Oxsil 320N of 3.13% was required

Nestin Expression in Embryonic and Adult Human Teeth under Normal and Pathological Conditions

Nestin is an intermediate filament most related to neurofilaments and expressed predominantly in the developing nervous system and muscles. In the present study we examined the in vivo distribution of nestin in human teeth during embryonic development and in permanent teeth under normal and pathological conditions. The results show that nestin is first expressed at the bell stage and that its distribution is restricted in pulpal cells located at the cusp area of the fetal teeth. In young permanent teeth, nestin is found only in functional odontoblasts, which produce the hard tissue matrix of dentin. Expression is progressively down-regulated and nestin is absent from older permanent teeth. In carious and injured teeth, nestin expression is up-regulated in a selective manner in odontoblasts surrounding the injury site, showing a link between tissue repair competence and nestin up-regulation under pathological conditions. In an in vitro assay system of human dental pulp explants, nestin is up-regulated after local application of bone morphogenic protein-4. A similar effect is seen in cultures of primary pulp cells during their differentiation into odontoblasts. Taken together, these results suggest that nestin plays a potential role in odontoblast differentiation during normal and pathological conditions and that bone morphogenic protein-4 is involved in nestin up-regulation