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

Forming nacreous layer of the shells of the bivalves Atrina rigida and Pinctada margaritifera: An environmental- and cryo-scanning electron microscopy study

International audienceA key to understanding control over mineral formation in mollusk shells is the microenvironment inside the pre-formed 3-dimensional organic matrix framework where mineral forms. Much of what is known about nacre formation is from observations of the mature tissue. Although these studies have elucidated several important aspects of this process, the structure of the organic matrix and the microenvironment where the crystal nucleates and grows are very difficult to infer from observations of the mature nacre. Here, we use environmental- and cryo-scanning electron microscopy to investigate the organic matrix structure at the onset of mineralization in the nacre of two mollusk species: the bivalves Atrina rigida and Pinctada margaritifera. These two techniques allow the visualization of hydrated biological materials coupled with the preservation of the organic matrix close to physiological conditions. We identified a hydrated gel-like protein phase filling the space between two interlamellar sheets prior to mineral formation. The results are consistent with this phase being the silk-like proteins, and show that mineral formation does not occur in an aqueous solution, but in a hydrated gel-like medium. As the tablets grow, the silk-fibroin is pushed aside and becomes sandwiched between the mineral and the chitin layer

Effect of Langmuir monolayer of bovine serum albumin protein on the morphology of calcium carbonate

Bovine serum albumin (BSA) Langmuir monolayer, as a model of biomineralization-associated proteins, was used to study its effect on regulated biomineralization of calcium carbonate. The effects of the BSA Langmuir monolayer and the concentration of the subphase solution on the nucleation and growth processes and morphology of the calcium carbonate crystal were investigated. The morphology and polymorphic phase of the resulting calcium carbonate crystals were characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Moreover, the interaction mechanisms of the subphase solution with the BSA Langmuir monolayer were discussed. It was found that BSA Langmuir monolayer could be used as a template to successfully manipulate the polymorphic phase and crystal morphology of calcium carbonate and had obvious influence on the oriented crystallization and growth. The final morphology or aggregation mode of the calcite crystal was closely dependent on the concentration of calcium bicarbonate solution. It is expected that this research would help to better understand the mechanism of biomineralization by revealing the interactions between protein matrices and crystallization of calcium carbonate crystal.Comment: 4 pages, 4 figure

Cell Adhesion to Crystal Surfaces: A Model for Initial Stages in the Attachment of Cells to Solid Substrates

This study addresses the mechanism of the chirally-restricted, ROD-independent adhesion of A6 epithelial cells to the {011} faces of calcium {R,R)-tartrate tetrahydrate crystals. The extensive and rapid adhesion of the cells to these surfaces, in the presence or absence of serum proteins, is distinctly different from the extracellular matrix-mediated adhesion to conventional tissue culture surfaces or to the {101} faces of the same crystals. The differences are manifested by insensitivity to ATP depletion, to disruption of microfilaments and microtubules and even to formaldehyde fixation of the cells. Furthermore, trypsin pretreatment does not affect cell attachment to the {011} faces, nor does trypsin post-treatment cause cell detachment from the crystals. We also noticed that the rapid adhesion to the crystal surface bears several lines of similarity to the early temporal stages in cell adhesion to regular tissue culture surfaces. Based on these observations and additional theoretical considerations, it is proposed that ·the molecular interactions responsible for the cell adhesion to the {011} surfaces may serve as models for an early engagement stage in cell adhesion which precedes, and may be essential for, the formation of stable and long-term contacts

Nature-inspired calcium phosphate coatings : present status and novel advances in the science of mimicry

There has been a growing awareness in materials science that the adaptation of nature biological processes can lead to significant progresses in the controlled fabrication of advanced materials for an all range of applications. To learn from, understand and apply these natural processes for producing calcium phosphate coatings that are biologically similar to bone apatite, mimicking its properties, has driven the attention of many researchers in recent years. This article reviews the most relevant advances in this emerging research field, pointing out several approaches being introduced and explored by distinct laboratories

Biosynthesis of copper carbonate nanoparticles by ureolytic fungi

In this research, the ureolytic fungi Neurospora crassa, Pestalotiopsis sp. and Myrothecium gramineum were investigated for the preparation of nanoscale copper carbonate and the role of fungal extracellular protein in such mineral formation. After incubation in urea-modified media, carbonate-laden fungal supernatants were used for the precipitation of copper carbonate, with experimental results agreeing closely with those obtained using geochemical modelling (Geochemist's Workbench). Compared with commercial and chemically synthesized copper carbonate, the minerals obtained using fungal supernatants were nanoscale and showed varying morphologies. It was found that extracellular protein played an important role in determining the size and morphology of the carbonate minerals precipitated, and after mixture with CuCl2 and resultant copper carbonate precipitation, more than 80% protein was removed from the N. crassa supernatant. Moreover, with addition of extracellular protein extracted from different fungal supernatants or standard bovine serum albumin, more than 96% of protein was removed by carbonate mineral precipitation. These results provide direct experimental evidence for the preparation of copper carbonate nanoparticles utilizing fungal ureolytic activity and show that fungal extracellular protein plays an important role in the formation and size of specific nano metal carbonates. Such a process provides opportunities for production of specific and/or novel metal carbonate nanoparticles of applied relevance, and as precursors of other useful biomineral products such as oxides.</p

Shell we cook it? An experimental approach to the microarchaeological record of shellfish roasting

In this paper, we investigate the microarchaeological traces and archaeological visibility of shellfish cooking activities through a series of experimental procedures with direct roasting using wood-fueled fires and controlled heating in a muffle furnace. An interdisciplinary geoarchacological approach, combining micromorphology, FTIR (in transmission and ATR collection modes), TGA and XRD, was used to establish a baseline on the mineralogical transformation of heated shells from aragonite to calcite and diagnostic sedimentary traces produced by roasting fire features. Our experimental design focused on three main types of roasting procedures: the construction of shallow depressions with heated rocks (pebble cuvette experiments), placing shellfish on top of hot embers and ashes (fire below experiment), and by kindling short-lived fires on top of shellfish (fire above experiments). Our results suggest that similar shellfish roasting procedures will largely create microstratigraphic signatures of anthropogenically reworked combusted material spatially "disconnected" from the actual combustion locus. The construction of shallow earth ovens might entail an increased archaeological visibility, and some diagnostic signatures of in situ hearths can be obtained by fire below roasting activities. We also show that macroscopic visual modifications and mineralogical characterization of discarded shellfish might be indicative of specific cooking activities versus secondary burning.Max Planck Societyinfo:eu-repo/semantics/publishedVersio

Tuning of Crystal Nucleation and Growth by Proteins: Molecular Interactions at Solid-Liquid Interfaces in Biomineralization

The mineralized tissues of a bivalve mollusk and a sea urchin are both composed of calcium carbonate crystals that are intimately associated with acidic glycoproteins. In vitro studies in which carboxylate-, carbonate- and phosphate-containing crystals are grown in the presence of partially purified acidic glycoproteins from these two tissues show that some of these macro- molecules are able to interact specifically with certain crystal faces. Significantly all the affected crystal faces contain a common stereochemical motif. Interesting differences, however, were observed in the modes of interaction between the mollusk and sea urchin derived acidic glycoproteins. Only the former can induce oriented calcite nucleation in vitro and only the latter can interact from solution with specific calcite crystal faces. These differences are ascribed in part to the fact that the mollusk macromolecules are much more acidic than those from the sea urchin. Some of the acidic glycoproteins are also occluded inside the growing crystals. In the case of the sea urchin, and not of the mollusk, the proteins are preferentially located at specific crystal planes and their presence influences the mechanical properties of the crystal. A detailed study of these composite crystals by X-ray synchrotron radiation shows how the presence of the protein influences the crystal mosaicity. The interactions revealed by these studies follow well defined stereochemical rules, tuned by electrostatic forces. They, in turn, provide new \u27insight into some of the basic underlying processes occurring in biomineralization