No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The influence of mineral particles on fibroblast behaviour: A comparative study
Abstract
Minerals are versatile tools utilised to modify and control the physical-chemical and functional properties of substrates. Those properties include ones directing cell fate; thus, minerals can potentially provide a direct and inexpensive method to manipulate cell behaviour. This paper shows how different minerals influence human dermal fibroblast behaviour depending on their properties. Different calcium carbonates, calcium sulphates, silica, silicates, and titanium dioxide were characterised using TEM, ATR-FTIR, and zeta potential measurements. Mineral-cell interactions were analysed through MTT assay, LDH assay, calcein AM staining, live cell imaging, immunofluorescence staining, western blot, and extra/intracellular calcium measurements. Results show that the interaction of the fibroblasts with the minerals was governed by a shared period of adaptation, followed by increased proliferation, growth inhibition, or increased toxicity. Properties such as size, ion release and chemical composition had a direct influence on the cells leading to cell agglomeration, morphological changes, and the possible formation of protein-mineral complexes. In addition, zeta potential and FTIR measurements of the minerals showed adsorption of the cell culture media onto the particles. This article provides fundamental insight into the mineral-fibroblast interactions, and makes it possible to arrange the minerals according to the time-dependent cellular response.
... Several studies have shown that TiO 2 NPs exhibit higher toxicity when compared to particles that do not have a nanometric scale, which is associated with the most significant toxic effects among smaller particle sizes [3,19,20]. Size is a very important characteristic since NPs can be internalized and trigger a toxic response to the cellular system [21][22][23][24]. Besides possible internalization, NPs can induce pores in the cell membrane, or even the destruction of the cell membrane and organelles, and also bind to macromolecules, altering their structure and function, causing damage to cell function and communication [25,26]. ...
... Although many studies on nanotoxicity are produced every year [23,24,[34][35][36][37][38], the mechanisms that trigger cytotoxicity are not yet fully elucidated. Moreover, the cellular effects of NPs are dependent on several factors, such as particle size, surface ligands, their agglomeration state, as well as the dose and exposure time in addition to the cell line being studied [3,22,26]. ...
Background/aims:
Titanium dioxide nanoparticles (TiO2 NPs) are extensively applied in the industry due to their photocatalytic potential, low cost, and considerably low toxicity. However, new unrelated physicochemical properties and the wide use of nanoparticles brought concern about their toxic effects. Thereby, we evaluated the cytotoxicity of a TiO2 NP composed of anatase and functionalized with sodium carboxylate ligands in a murine fibroblast cell line (LA-9).
Methods:
Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and ATR-FTIR spectroscopy were applied to determine nanoparticle physicochemical properties. The cell viability (MTT assay) and clonogenic survival were analyzed in fibroblasts exposed to TiO2 NP (50, 150, and 250 µg/mL) after 24h. Moreover, oxidative stress, proinflammatory state, and apoptosis were evaluated after 24h.
Results:
TiO2 NP characterization showed an increased hydrodynamic size (3.57 to 7.62 nm) due to solvent composition and a heterogeneity dispersion in water and cell culture media. Also, we observed a zeta potential increased from -20 to -11 mV in function of protein adsorption. TiO2 NP reduced fibroblast cell viability and induced ROS production at the highest concentrations (150 and 250 µg/mL). Moreover, TiO2 NP reduced the fibroblasts clonogenic survival at the highest concentration (250 µg/mL) on the 7th day after the 24h exposure. Nevertheless, TiO2 NP did not affect the fibroblast proinflammatory cytokines (IL-6 and TNF) secretion at any condition. Early and late apoptotic fibroblast cells were detected only at 150 µg/mL TiO2 NP after 24h.
Conclusion:
Probably, TiO2 NP photocatalytic activity unbalanced ROS production which induced apoptosis and consequently reduced cell viability and metabolic activity at higher concentrations.
... Similar to the bone and dental materials, most studies on dermatological biomaterials stop at the microstructure level. Soto Veliz et al. [29] showed the influence of mineral composition of 18 different minerals on the growth and propagation of human dermal fibroblast cells. Variation in zeta potential was masked by the previously observed adsorbed protein corona on the particles [30]. ...
The success of science and engineering in increasing life span and quality of life has generated difficult challenges to sustaining health span. Aging populations and poor health patterns have increased the need for replacement organs, tissues, and limbs that must do more, longer. To meet this need, advanced synthetic biomaterials that mimic or encourage native tissue regrowth are needed. We highlight recent advances in tissue engineering and regenerative medicine for bone, skin, and cardio scaffolds, grafts, and replacements. Recognizing the complexity of multiscale development and testing, we use these as case studies to propose a hierarchical integration pyramid to assist the rapid translation of these developments from benchtop to bedside.
Inorganic nanoparticles (NPs) are gaining increasing attention in nanomedicine because of their stimuli responsiveness, which allows combining therapy with diagnosis. However, little information is known about their interaction with intracellular or plasma proteins when they are introduced in a biological environment. Here we present atomistic molecular dynamics (MD) simulations investigating the case study of dopamine-functionalized TiO2 nanoparticles and two proteins that are overexpressed in cancer cells, i.e. PARP1 and HSP90, since experiments proved them to be the main components of the corona in cell cultures. The mechanism and the nature of the interaction (electrostatic, van der Waals, H-bonds, etc.) is unravelled by defining the protein residues that are more frequently in contact with the NPs, the extent of contact surface area and the variations in the protein secondary structures, at different pH and ionic strength conditions of the solution where they are immersed to simulate a realistic biological environment. The effects of the NP surface functionalization and charge are also considered. Our MD results suggest that less acidic intracellular pH conditions in the presence of cytosolic ionic strength enhance PARP1 interaction with the nanoparticle, whereas the HSP90 contribution is partly weakened, providing a rational explanation to existing experimental observations.
Mineral coatings manipulate surface properties such as roughness, porosity, wettability and surface energy. Properties that are known to determine cell behaviour. Therefore, mineral coatings can potentially be used to manipulate cell fate. This paper studies mineral-cell interactions through coatings in a stacked cell culture platform. Minerals were chosen according to their influence on Human Dermal Fibroblasts (HDFs): calcium carbonate, calcium sulphates, and kaolin. Mineral coatings were formulated with the additives latex, sorbitol, polyvinyl alcohol (PVOH) and TEMPO-oxidised cellulose nanofibrils (CNF-T). The coatings were placed as a bottom or top of the device, for a direct or indirect interaction with HDFs, respectively. Cells were seeded, in various densities, to the bottom of the device; and cell density and confluency were monitored in time. Overall, results show that the coating interaction is influenced at first by the cell seeding density. Scarce cell seeding density limits adaptability to the new environment, while an abundant one encourages confluency in time. In between those densities, coating formulation plays the next major role. Calcium carbonate promoted HDFs growth the most as expected, but the response to the rest of minerals depended on the coating additive. CNF-T encouraged proliferation even for kaolin, a mineral with long-term toxicity to HDFs, while PVOH induced a detrimental effect on HDF growth regardless of the mineral. At last, the placement of the coated layer provided insights on the contact-dependency of each response. This study highlights the importance of the experimental design, including coating formulation, when investigating cellular response to biomaterials.
Crystalline silica (SiO 2 ) particles have very strong toxicity to the lungs, and silicosis is an excessive pulmonary interstitial remodeling disease that follows persistent SiO 2 injury. We showed here that DNA double strand breaks (DSBs) and apoptosis were aggravated during rat silicosis induced by SiO 2 exposure. Ac-SDKP attenuates lung parenchymal distortion and collagen deposition, and decreases the expression of γH2AX, p21, and cleaved caspase-3, as well as improves the reduction of pulmonary function caused by silicosis. In vitro, we found an evolution of smooth muscle actin α (α-SMA), collagen type I (Col I) in both A549 and MRC-5 cells in response to transforming growth factor-beta 1 (TGF-β1) + SiO 2 . Only A549 cells showed any reduction in the rate of apoptosis induced by the double stimulation, because of the anti-apoptotic effects of TGF-β1. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is an anti-fibrotic tetrapeptide. It also has the ability to promote the apoptosis of leukemia cells. However its role in promoting cell apoptosis in silicosis is still unknown. We here found that Ac-SDKP could induce cell apoptosis and inhibit fibrotic response in A549 and MRC-5 cells treated with TGF-β1 + SiO 2 , and these effects depended on regulation of α-tubulin acetyltransferase 1 (α-TAT1). These findings suggest that Ac-SDKP may have therapeutic value in the treatment of silicotic fibrosis.
Natural two-dimensional (2D) kaolinite nanoclay has been incorporated into an emerging drug delivery system. The basal spacing of the kaolinite nanoclay was expanded from 0.72 to 4.16 nm through the intercalation of various organic guest species of different chain lengths, which can increase the efficiency in drug delivery and reduce the toxicity of doxorubicin (DOX). Original kaolinite (Kaolin) and the Kaolin intercalation compounds exhibited a high level of biocompatibility and very low toxicity towards cells of pancreatic cancer, gastric cancer, prostate cancer, breast cancer, colorectal cancer, esophageal cancer, and differentiated thyroid cancer. However, lung cancer and hepatocellular cancer cells need more strict compositional, structural, and morphological modulations for drug delivery carriers. DOX-Kaolin and the DOX-Kaolin intercalation compounds showed dramatically faster drug release in moderately acidic solution than in neutral condition, and exhibited enhanced therapeutic effects against ten model cancer cell cultures in a dose-dependent manner. The use of 2D nanoclay materials for a novel drug delivery system could feasibly pave a way towards high-performance nanotherapeutics, with superior antitumor efficacy and significantly reduced side effects.
Open image in new window
Organisms are constantly exposed to acute and chronic stress conditions, which challenge the maintenance of protein homeostasis. Heat Shock Proteins (HSPs) function as molecular chaperones to stabilize protein structures, facilitate refolding of misfolded proteins, and prevent uncontrolled protein aggregation. Therefore, HSPs serve as the first and last line of defense in the events of proteotoxic stresses. The stress-inducible expression of HSPs, which is a hallmark of the heat shock response, is under strict control of evolutionary conserved transcription factors, known as Heat Shock Factors (HSFs). Invertebrates have only a single HSF, whereas the HSF family in vertebrates consists of multiple members. Direct interactions of HSFs with various proteins, including HSPs, chromatin-associated proteins, and other HSF family members as well as their complex post-translational modifications, allow these transcription factors to function not only in stress responses but also in many other biological processes. For example, mammalian HSF1, HSF2 and HSF4 are fundamental for normal organismal development and healthy aging. Moreover, recent discoveries have highlighted the importance of HSFs in tumorigenesis, neurodegeneration, and metabolic disorders, which positions them as promising therapeutic targets in multiple human diseases. In this review, we focus on recent advances in the HSF biology and discuss the functional impact of HSFs on stress responses, development, aging, and age-related pathologies.
In this study the effect of dry grinding on hydrophobicity, surface free energy (SFE), particle size distribution, surface area, porosity, oil absorption, and whiteness of talc was investigated. The dry grinding was performed in a vibrating ball mill at various grinding times (5-150 min) by keeping the grinding parameters constant such as the number of ball, ball size, the amount of talc, vibration frequency and amplitude. Then, the contact angle measurements were performed on disc-shaped samples produced under a hydraulic press by using a sessile drop method with different liquids (water, formamide, diiodomethane, and ethylene glycol), and surface free energies (mJ/m2) were calculated according to OCG-AB (van Oss-Chaudhury-Good Acid-Base) method by using the obtained contact angle values. In addition, the physicochemical analyses given above were carried out for each ground sample. According to the obtained results, the water contact angle and SFE of the original sample were 63.800 and 48.70 mJ/m2, respectively. The lowest and highest contact angle values for the samples were obtained as 59.300 and 70.770 at grinding times for 5 and 15 min, respectively. It was also determined that the grinding time over 30 min showed no significant effect on the contact angle and SFE values of the samples. Similarly, the grinding time vs. SFE, and the grinding time vs. contact angle curves showed a similar trend. Parallel to the increase in the surface area upon the grinding, a small increase in the oil absorption and whiteness of talc was also determined.
Paper has recently attracted increasing attention as a substrate for various biomedical applications. By modifying its physical and chemical properties, paper can be used as an alternative to conventional cell culture substrates. Because it can be stacked into a three-dimensional (3D) structure, which can better mimic the in vivo cell microenvironment. Paper has shown great potential as a 3D cell culture platform for developing normal and diseased models. This platform gives precise control over extracellular matrix (ECM) composition as well as cell distribution and precise analysis of the interactions between cells. Paper-based platforms have been applied for pathophysiological studies and therapeutic intervention studies. In this paper, we first discuss the modifications of the physical and chemical properties of paper to develop various 2D and 3D cell culture platforms. We then review the applications of paper-based cell culture platforms for the construction of in vitro disease models, drug screening, and cell cryopreservation applications. Because of its advantages such as biocompatibility, eco-friendliness, cost efficiency, and ease of large-scale production, we believe that paper-based cell culture platforms would play an important role in the fields of biomedicine.
In this study the effect of amorphous calcium carbonate (ACC) microparticles and amorphous calcium polyphosphate (polyP) microparticles (termed aCa-polyP-MP) on bone mineral forming cells/tissue was investigated in vitro and in vivo. The ACC particles (termed ACC-P10-MP) were prepared in the presence of Na-polyP. Only the combinations of polyP and ACC microparticles enhanced the proliferation rate of human mesenchymal stem cells (MSCs). Gene expression studies revealed that ACC causes an upregulation of the expression of the cell membrane-associated carbonic anhydrase IX (CA IX; formation of ACC), while the transcript level of the alkaline phosphatase (ALP; liberation of orthophosphate from polyP) changes only relatively little. In contrast, aCa-polyP-MP primarily induces ALP expression. If both components are applied together a strong stimulation of expression of both marker genes is observed. In order to investigate whether ACC also enhances bone regeneration induced by polyP in vivo, the particles were encapsulated into PLGA (poly(d,l-lactide-co-glycolide)) microspheres (diameter ∼800 μm) and implanted into rat critical-size calvarial defects. The studies revealed that animals that received aCa-polyP-MP microspheres showed an increased rate of regeneration compared to β-tri-calcium phosphate (β-TCP) controls. This effect is even accelerated if microspheres with both aCa-polyP-MP and ACC-P10-MP (1 : 1 weight ratio) are applied, resulting in an almost complete restoration of the defect area after 12 weeks. qRT-PCR analyses of tissue sections through the regeneration zone with microspheres containing both aCa-polyP-MP and ACC-P10-MP revealed a significantly higher upregulation of expression of the marker genes compared to each of the components alone. The Young's moduli for microspheres containing aCa-polyP-MP (1.74 MPa) and aCa-polyP-MP/ACC-P10-MP (2.38 MPa) were markedly higher compared to β-TCP-controls (0.63 mPa). Our results show that the combined application of ACC and Ca-polyP (both in the amorphous state) opens new strategies for the development of regenerative implants for the reconstruction of bone defects.
The ability to selectively kill cancerous cell populations while leaving healthy cells unaffected is a key goal in anticancer therapeutics. The use of nanoporous silica-based materials as drug-delivery vehicles has recently proven successful, yet production of these materials requires costly and toxic chemicals. Here we use diatom microalgae-derived nanoporous biosilica to deliver chemotherapeutic drugs to cancer cells. The diatom Thalassiosira pseudonana is genetically engineered to display an IgG-binding domain of protein G on the biosilica surface, enabling attachment of cell-targeting antibodies. Neuroblastoma and B-lymphoma cells are selectively targeted and killed by biosilica displaying specific antibodies sorbed with drug-loaded nanoparticles. Treatment with the same biosilica leads to tumour growth regression in a subcutaneous mouse xenograft model of neuroblastoma. These data indicate that genetically engineered biosilica frustules may be used as versatile 'backpacks' for the targeted delivery of poorly water-soluble anticancer drugs to tumour sites.
Introduction:
Calcium carbonate (CaCO3) has broad biomedical utilizations owing to its availability, low cost, safety, biocompatibility, pH-sensitivity and slow biodegradability. Recently, there has been widespread interest in their application as drug delivery systems for different groups of drugs. Among them, CaCO3 nanoparticles have exhibited promising potential as drug carriers targeting cancer tissues and cells. The pH-dependent properties, alongside the potential to be functionalized with targeting agents give them the unique property that can be used in targeted delivery systems for anticancer drugs. Also, due to the slow degradation of CaCO3 matrices, these nanoparticles can be used as sustained release systems to retain drugs in cancer tissues for longer times after administration. Areas covered: Development of drug delivery carriers using CaCO3 nanoparticles has been reviewed. The current state of CaCO3 nanoparticles as cancer drug delivery systems with focus on their special properties like pH-sensitivity and biodegradability has also been evaluated. Expert opinion: According to our review, CaCO3 nanoparticles, owing to their special characteristics, will have a potential role in safe and efficient cancer treatment in future.
Inorganic cements have found utility in tissue replacement since the late nineteenth century, one of the first examples being calcium sulphates in the augmentation of bone defects. In the intervening period of time countless formulations of calcium phosphate, sulphate and silicate cement have been researched and as a result, many are now commercially available for a variety of biomedical applications. This review summarises the applications, formulations, advantages and drawbacks of such inorganic cements, suggesting future work that will drive progress in this area into the future of biomaterials research.
Worldwide increases in fluvial fine sediment are a threat to aquatic animal health. Fluvial fine sediment is always a mixture of particles whose mineralogical composition differs depending on the sediment source and catchment area geology. Nonetheless, whether particle impact in aquatic organisms differs between mineral species remains to be investigated. This study applied an in vitro approach to evaluate cytotoxicity and uptake of four common fluvial mineral particles (quartz, feldspar, mica, and kaolin; concentrations: 10, 50, 250 mg L-1) in the rainbow trout epithelial gill cell line RTgill-W1. Cells were exposed for 24, 48, 72, and 96 h. Cytotoxicity assays for cell membrane integrity (propidium iodide assay), oxidative stress (H2DCF-DA assay), and metabolic activity (MTT assay) were applied. These assays were complemented with cell counts and transmission electron microscopy. Regardless of mineral species, particles ≤2 µm in diameter were taken up by the cells, suggesting that particles of all mineral species came into contact and interacted with the cells. Not all particles, however, caused strong cytotoxicity: Among all assays the tectosilicates quartz and feldspar caused sporadic maximum changes of 0.8-1.2-fold compared to controls. In contrast, cytotoxicity of the clay particles was distinctly stronger and even differed between the two particle types: mica induced concentration-dependent increases in free radicals, with consistent 1.6-1.8-fold-changes at the 250 mg L-1 concentration, and a dilated endoplasmic reticulum. Kaolin caused concentration-dependent increases in cell membrane damage, with consistent 1.3-1.6-fold increases at the 250 mg L-1 concentration. All effects occurred in the presence or absence of 10% fetal bovine serum. Cell numbers per se were marginally affected. Results indicate that (i.) natural mineral particles can be cytotoxic to gill epithelial cells, (ii.) their cytotoxic potential differs between mineral species, with clay particles being more cytotoxic, and (iii.) some clays might induce effects comparable to engineered nanoparticles.
Introduction:
Heat shock protein 90 (HSP90) serves as a critical facilitator for oncogene addiction. There has been augmenting enthusiasm in pursuing HSP90 as an anticancer strategy. In fact, since the initial serendipitous discovery that geldanamycin (GM) inhibits HSP90, the field has rapidly moved from proof-of-concept clinical studies with GM derivatives to novel second-generation inhibitors.
Areas covered:
The authors highlight the current status of the second-generation HSP90 inhibitors in clinical development. Herein, the authors note the lessons learned from the completed clinical trials of first- and second-generation inhibitors and describe various assays attempting to serve for a more rational implementation of these agents to cancer treatment. Finally, the authors discuss the future perspectives for this promising class of agents.
Expert opinion:
The knowledge gained thus far provides perhaps only a glimpse at the potential of HSP90 for which there is still much work to be done. Lessons from the clinical trials suggest that HSP90 therapy would advance at a faster pace if patient selection and tumor pharmacokinetics of these drugs were better understood and applied to their clinical development. It is also evident that combining HSP90 inhibitors with other potent anticancer therapies holds great promise not only due to synergistic antitumor activity but also due to the potential of prolonging or preventing the development of drug resistance.
Fiji is a distribution of the popular open-source software ImageJ focused on biological-image analysis. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms. Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biology research communities.
Albumin has a long historical involvement in design of media for the successful culture of mammalian cells, in both the research and commercial fields. The potential application of albumins, bovine or human serum albumin, for cell culture is a by-product of the physico-chemical, biochemical and cell-specific properties of the molecule. In this review an analysis of these features of albumin leads to a consideration of the extracellular and intracellular actions of the molecule, and importantly the role of its interactions with numerous ligands or bioactive factors that influence the growth of cells in culture: these include hormones, growth factors, lipids, amino acids, metal ions, reactive oxygen and nitrogen species to name a few. The interaction of albumin with the cell in relation to these co-factors has a potential impact on metabolic and biosynthetic activity, cell proliferation and survival. Application of this knowledge to improve the performance in manufacturing biotechnology and in the emerging uses of cell culture for tissue engineering and stem cell derived therapies is an important prospect.
Stochasticity pervades life at the cellular level. Cells receive stochastic signals, perform detection and transduction with stochastic biochemistry, and grow and die in stochastic environments. Here we review progress in going from the molecular details to the information-processing strategies cells use in their decision-making. Such strategies are fundamentally influenced by stochasticity. We argue that the cellular decision-making can only be probabilistic and occurs at three levels. First, cells must infer from noisy signals the probable current and anticipated future state of their environment. Second, they must weigh the costs and benefits of each potential response, given that future. Third, cells must decide in the presence of other, potentially competitive, decision-makers. In this context, we discuss cooperative responses where some individuals can appear to sacrifice for the common good. We believe that decision-making strategies will be conserved, with comparatively few strategies being implemented by different biochemical mechanisms in many organisms. Determining the strategy of a decision-making network provides a potentially powerful coarse-graining that links systems and evolutionary biology to understand biological design.
Titanium (Ti) and its alloys are extensively used in the manufacture of implants because they have biocompatibility. The production of a nanostructured surface can be achieved by means of titanium dioxide nanotubes (TNTs) which can have dimensions equivalent to the nanometric components of human bone, in addition to increasing the efficiency of such implants. The search is ongoing for ways to improve the performance of these TNTs in terms of their functionalization through coating these nanotubular matrices with biomolecules. The biocompatibility of the functionalized TNTs can be improved by promoting rapid osseointegration, by preventing the adhesion of bacteria on such surfaces and/or by promoting a more sustained local release of drugs that are loaded into such TNTs. In addition to the implants, these nanotubular matrices have been used in the manufacture of high-performance biosensors capable of immobilizing principally enzymes on their surfaces, which has possible use in disease diagnosis. The objective of this review is to show the main techniques of immobilization of biomolecules in TNTs, evidencing the most recent applications of bioactive molecules that have been functionalized in the nanotubular matrices for use in implants and biosensors. This surveillance also proposes a new class of biomolecules that can be used to functionalize these nanostructured surfaces, lectins.
Cellular invasion is the gateway to metastasis, which is the leading cause of cancer-related deaths. Invasion is driven by a number chemical and mechanical stresses that arise in the tumor microenvironment. In vitro assays are needed for the systematic study of cancer progress. To be truly predictive, these assays must generate tissue-like environments that can be experimentally controlled and manipulated. While two-dimensional (2D) monolayer cultures are easily assembled and evaluated, they lack the extracellular components needed to assess invasion. Three-dimensional (3D) cultures are better suited for invasion studies because they generate cellular phenotypes, that are more representative of those found in vivo than monolayer cultures. This feature article provides an overview of four invasion assay platforms. We focus on paper-based cultures, an emerging 3D culture platform capable of generating tissue-like structures and quantifying cellular invasion in defined extracellular gradients. Paper-based cultures are as easily assembled and analyzed as monolayers, but provide an experimentally powerful platform capable of supporting: co-cultures and representative extracellular environments; experimentally controlled gradients; readouts capable of quantifying, discerning, and separating cells based on their invasiveness. With a series of examples we highlight the potential of paper-based cultures, and discuss how they stack up against other invasion platforms.
Calcium sulfate (CS), also known as POP (Plaster of Paris) is a self-setting, biocompatible and osteoconductive biomaterial with a long history for the treatment of skeletal defects. However, calcium sulfate cements show a too fast resorption rate and are unable to provide a long term 3D framework during the osteogenesis process. In our previous studies, it was found that the incorporation of CaCO3 and CaCO3 hydrogel provided enhanced mechanical and degradation properties of POP composites. Furthermore, it was also found that the use of cinnamaldehyde to crosslink CaCO3 hydrogel may have some advantages, e.g. to crosslink the hydrogel and to act as anti-inflammatory control agent. The objective of the current study was to evaluate the effect of adding cinnamaldehyde crosslinked CaCO3 hydrogel into POP on the diametral tensile strength, weight loss, age swelling, degradation, cinnamaldehyde release and porosity. The following composites were prepared: POP/HCin-025 (25% addition of hydrogel microsphere) and POP/HCin-050 (50% addition of hydrogel microsphere). The composites were assessed on their diametral tensile strength, weight loss of the POP composite, age swelling, degradation of the hydrogel CaCO3 , cinnamaldehyde release and porosity, as well as XRD-patterns and FT-IR spectra. It was confirmed from the study that incorporation of cinnamaldehyde into CaCO3 hydrogel system significantly increased the mechanical strength of the POP composite. Weight loss, swelling ratio in both acid to neutral pH and biodegradability of the POP composites were controllable by the addition of cinnamaldehyde-CaCO3 hydrogel. Moreover, the cinnamaldehyde incorporated into the hydrogel was proven to be released in a controlled manner. This article is protected by copyright. All rights reserved.
Cytoplasmic vacuolization (also called cytoplasmic vacuolation) is a well-known morphological phenomenon observed in mammalian cells after exposure to bacterial or viral pathogens as well as to various natural and artificial low-molecular-weight compounds. Vacuolization often accompanies cell death; however, its role in cell death processes remains unclear. This can be attributed to studying vacuolization at the level of morphology for many years. At the same time, new data on the molecular mechanisms of the vacuole formation and structure have become available. In addition, numerous examples of the association between vacuolization and previously unknown cell death types have been reported. Here, we review these data to make a deeper insight into the role of cytoplasmic vacuolization in cell death and survival.
Beginning with the crystallographic structures of kaolin, talc and calcite, the dominant morphologies of white pigments typically used in the paper industry are discussed in relation to their specific functions as fillers and coating pigments. Control of particle size, its measurement and the response of different minerals to comminution are discussed with particular reference to the effects on pigment packing characteristics. The practical application of pigments in aqueous systems and the inherent demands for dispersion and stabilization are outlined. Functional aspects of coverage and optical performance are dominant in the increasing market demand for improved paper properties of printability, uniformity and brightness, and the basis for these properties are summarized. Practical observation of ink-on-paper interactions using rheological methods in combination with in-situ ink tack measurements are shown to provide a direct measure of offset ink solids content and viscosity during the initial stages of absorption after printing. Based on fundamental studies of surface pores and the absorption dynamic of fluid imbibed into porous network systems the article outlines the link with printability and briefly presents the way forward to some potential strategies to meet the emerging technological demands of the printing media of the future.
Technology in microscopy advances rapidly, enabling increasingly affordable, faster, and more precise quantitative biomedical imaging, which necessitates correspondingly more-advanced image processing and analysis techniques. A wide range of software is available-from commercial to academic, special-purpose to Swiss army knife, small to large-but a key characteristic of software that is suitable for scientific inquiry is its accessibility. Open-source software is ideal for scientific endeavors because it can be freely inspected, modified, and redistributed; in particular, the open-software platform ImageJ has had a huge impact on the life sciences, and continues to do so. From its inception, ImageJ has grown significantly due largely to being freely available and its vibrant and helpful user community. Scientists as diverse as interested hobbyists, technical assistants, students, scientific staff, and advanced biology researchers use ImageJ on a daily basis, and exchange knowledge via its dedicated mailing list. Uses of ImageJ range from data visualization and teaching to advanced image processing and statistical analysis. The software's extensibility continues to attract biologists at all career stages as well as computer scientists who wish to effectively implement specific image-processing algorithms. In this review, we use the ImageJ project as a case study of how open-source software fosters its suites of software tools, making multitudes of image-analysis technology easily accessible to the scientific community. We specifically explore what makes ImageJ so popular, how it impacts the life sciences, how it inspires other projects, and how it is self-influenced by coevolving projects within the ImageJ ecosystem. Mol. Reprod. Dev. 2015. © 2015 Wiley Periodicals, Inc.
© 2015 Wiley Periodicals, Inc.
Engineering scaffolds combinging natural biomineral and artificially synthesized material hold promising potential for bone tissue regeneration. In this study, novel bioactive calcium sulfate/oyster shell (CS/OS) composites were prepared. Comparing to CS scaffold, the CS/OS composites with a controllable degradation rate displayed enhanced mineral nodule formation, higher alkaline phosphate (ALP) activity and increased proliferation rate while treated osteocytes. In CS/OS composites group, elevated mRNA levels of key osteogenic genes including bone morphogenetic protein-2 (BMP-2), runt-related transcription factor 2 (Runx2), osterix (Osx), and osteocalcin (OCN) were observed. Furthermore, The up-regulation of BMP-2 and type I collagen (COL-Ⅰ) was observed for CS/OS composites relative to a CS group. Scaffolds were implanted into critical-sized femur cavity defects in rabbits to investigate the osteogenic capacity of the composites in vivo. The CS/OS scaffolds with proper suitable times and mechanical strength strongly promoted osteogenic tissue regeneration relative to the regeneration capacity of CS scaffolds, as indicated by the results of histological staining. These results suggest that the OS-modified CS engineering scaffolds with improved mechanical properties and bioactivity would facilitate the development of a new strategy for clinic bone defect regeneration.
In this study, a facile method to modify nanostructured calcium carbonate (CaCO3) gene delivery systems by adding calcium phosphate (CaP) component was developed. CaCO3/CaP/DNA nanoparticles were prepared by the co-precipitation of Ca(2+) ions with plasmid DNA in the presence of carbonate and phosphate ions. For comparison, CaCO3/DNA nanoparticles and CaP/DNA co-precipitates were also prepared. The effects of carbonate ion/phosphate ion (CO3(2-)/PO4(3-)) ratio on the particle size and gene delivery efficiency were investigated. With an appropriate CO3(2-)/PO4(3-) ratio, the co-existence of carbonate and phosphate ions could control the size of co-precipitates effectively, and CaCO3/CaP/DNA nanoparticles with a decreased size and improved stability could be obtained. The in vitro gene transfections mediated by different nanoparticles in 293T cells and HeLa cells were carried out, using pGL3-Luc as a reporter plasmid. The gene transfection efficiency of CaCO3/CaP/DNA nanoparticles could be significantly improved as compared with CaCO3/DNA nanoparticles and CaP/DNA co-precipitates. The confocal microscopy study indicated that the cellular uptake and nuclear localization of CaCO3/CaP/DNA nanoparticles were significantly enhanced as compared with unmodified CaCO3/DNA nanoparticles.
Diatomaceous earth (DE), naturally available silica, originated from fossilized diatoms has been explored for use in drug delivery applications as a potential substitute for synthetic silica materials. The aim of this study is to explore the influence of particle size, morphology and surface modifications of diatom silica microparticles on their drug release properties. Raw DE materials was purified and prepared to obtain high purity DE silica porous particles with different size and morphologies. Comparative scanning electron microscope and particle characterization confirmed their particle size including irregularly shaped silica particles (size 0.1–1 μm, classified as “fine”), mixed fractions (size 1–10 μm, classified as “mixture”) and pure, unbroken DE structures (size 10–15 μm, classified as “entire”). Surface modification of DE with silanes and phosphonic acids was performed using standard silanization and phosphonation process to obtain surface with hydrophilic and hydrophobic properties. Water insoluble (indomethacin) and water soluble (gentamicin) drugs were loaded in DE particles to study their drug release performances. In vitro drug release studies were performed over 1–4 weeks, to examine the impact of the particle size and hydrophilic/hydrophobic functional groups. The release studies showed a biphasic pattern, comprising an initial burst release for 6 h, followed by near-zero order sustained release. This study demonstrates the potential of silica DE particles as a natural carrier for water soluble and insoluble drugs with release controlled by their morphological and interfacial properties.
Osmotic pressure measurements are reported as a function of bovine serum albumin (BSA) concentration in 0.15 M sodium chloride at pH 4.5, 5.4, and 7.4. The measured values increased markedly with increasing BSA concentration and with increasing pH (and therefore increasing macroion charge). At a concentration of 450 g/liter solution and a pH of 7.4, osmotic pressure was nearly five atmospheres, which is more than four times the value measured at the same concentration and a pH of 4.5 and about 30 times the value expected for an ideal solution. A semi-empirical analytical expression was developed which gave good agreement between prediction and the experimental data of this and other studies. The data were also compared to the prediction of a three-term virial equation wherein the second and third virial coefficients were calculated by using McMillan-Mayer solution theory. The expression for the potential of mean force was obtained by comparing various contributions to the potential energy of interaction. The terms for electrostatic repulsion and dispersion attraction are the same as those used in the DLVO theory of colloid stability. The predicted curves are of the correct order of magnitude and follow the correct qualitative trend with pH, but they fail to display the strong pH-dependence of the data. The factors responsible for this deficiency are assessed and opportunities for developing a more realistic potential function are identified.
The use of paper-based test platforms in cell culture experiments is demonstrated. The arrays used for 2D cell cultures were prepared by printing patterned structures on a paper substrate by using a hydrophobic PDMS ink. The non-printed, PDMS-free areas formed the array for the cell growth experiments. Cell imaging was enabled by using a lipophilic staining agent. A set of coated paper substrates was prepared to study the effect of the physicochemical properties of the substrate (topography, roughness and surface energetics) on cell attachment and growth. The studied paper substrates were found to be cell-repellent or cell-supporting. Cell growth was supported by substrates with a high bearing area, low surface area ratio (S(dr)), high total surface free energy and an intermediate electron donor surface energy component. The cells were grown to a full confluency during 72 hours.
Due to the critical role of heat shock protein 90 (HSP90) in regulating the stability, activity and intracellular sorting of its client proteins involved in multiple oncogenic processes, HSP90 inhibitors are promising therapeutic agents for cancer treatment. In cancer cells, HSP90 client proteins play a major role in oncogenic signal transduction (i.e., mutant epidermal growth factor receptor), angiogenesis (i.e., vascular endothelial growth factor), anti-apoptosis (i.e., AKT), and metastasis (i.e., matrix metalloproteinase 2 and CD91), processes central to maintaining the cancer phenotype. Thus, HSP90 has emerged as a viable target for antitumor drug development, and several HSP90 inhibitors have transitioned to clinical trials. HSP90 inhibitors include geldanamycin and its derivatives (i.e., tanespimycin, alvespimycin, IPI-504), synthetic and small molecule inhibitors (i.e., AUY922, AT13387, STA9090, MPC3100), other inhibitors of HSP90 and its isoforms (i.e., shepherdin and 5'-N-ethylcarboxamideadenosine). With more than 200 "client" proteins, many of them meta-stable and oncogenic, HSP90 inhibition can affect an array of tumors. Here we review the molecular structure of HSP90, structural features of HSP90 inhibition, pharmacodynamic effects and tumor responses in clinical trials of HSP90 inhibitors. We also discuss lessons learned from completed clinical trials of HSP90 inhibitors, and future directions for these promising therapeutic agents.
The hydration of calcium sulphate hemihydrate (CaSO4·0.5H2O) leading to the crystallization of gypsum (calcium sulphate dihydrate – CaSO4·2H2O) has been the subject of several investigations over a long period and a vast amount of data is widely distributed throughout in the literature. In this review article an overall picture of the subject is presented. The properties of the two hemihydrates (α- and β-), their hydration characteristics, the mechanism of their hydration and the crystal growth of gypsum are discussed. Additives modify the microstructures of the hardened gypsum and reduce its strength. A probable mechanism is discussed.
This paper reports the preparation of CaCO3 microcapsules and the direct encapsulation of biomacromolecules such as bovine serum albumin (BSA) and duplex DNA into the CaCO3 microcapsules. Vacant CaCO3 microcapsules were effectively obtained by interfacial reaction method using carbonate salts and calcium salts, which were dissolved in inner water phase or outer one, respectively. For the fabrication of microcapsule structure, the formation of vaterite as a metastable phase of calcium carbonate crystal was an important factor. When some biomacromolecules were dissolved in the aqueous solution of (NH4)2CO3 as the inner water phase, these macromolecules were successfully encapsulated into CaCO3 microcapsules. Biomacromolecules included in the microcapsules scarcely eliminated without the fracture of the microcapsule particles. These properties of encapsulated biomacromolecules might be utilized in various bio-related materials.
Chemical and morphological characteristics of a biomaterial surface are thought to play an important role in determining cellular differentiation and apoptosis. In this report, we investigate the effect of nanoparticle (NP) assemblies arranged on a flat substrate on cytoskeletal organization, proliferation and metabolic activity on two cell types, Bovine aortic endothelial cells (BAECs) and mouse calvarial preosteoblasts (MC3T3-E1). To vary roughness without altering chemistry, glass substrates were coated with monodispersed silica nanoparticles of 50, 100 and 300 nm in diameter. The impact of surface roughness at the nanoscale on cell morphology was studied by quantifying cell spreading, shape, cytoskeletal F-actin alignment, and recruitment of focal adhesion complexes (FAC) using image analysis. Metabolic activity was followed using a thiazolyl blue tetrazolium bromide assay. In the two cell types tested, surface roughness introduced by nanoparticles had cell type specific effects on cell morphology and metabolism. While BAEC on NP-modified substrates exhibited smaller cell areas and fewer focal adhesion complexes compared to BAEC grown on glass, MC3T3-E1 cells in contrast exhibited larger cell areas on NP-modified surfaces and an increased number of FACs, in comparison to unmodified glass. However, both cell types on 50 nm NP had the highest proliferation rates (comparable to glass control) whereas cells grown on 300 nm NP exhibited inhibited proliferation. Interestingly, for both cell types surface roughness promoted the formation of long, thick F-actin fibers, which aligned with the long axis of each cell. These findings are consistent with our earlier result that osteogenic differentiation of human mesenchymal progenitor cells is enhanced on NP-modified surfaces. Our finding that nanoroughness, as imparted by nanoparticle assemblies, effects cellular processes in a cell specific manner, can have far reaching consequences on the development of “smart” biomaterials especially for directing stem cell differentiation.
In our previous study we reported that the interaction of nanoparticles with cells can be influenced by particle shape, but until now the effect of particle shape on in vivo behavior remained poorly understood. In the present study, we control the fabrication of fluorescent mesoporous silica nanoparticles (MSNs) by varying the concentration of reaction reagents especially to design a series of shapes. Two different shaped fluorescent MSNs (aspect ratios, 1.5, 5) were specially designed, and the effects of particle shape on biodistribution, clearance and biocompatibility in vivo were investigated. Organ distributions show that intravenously administrated MSNs are mainly present in the liver, spleen and lung (>80%) and there is obvious particle shape effects on in vivo behaviors. Short-rod MSNs are easily trapped in the liver, while long-rod MSNs distribute in the spleen. MSNs with both aspect ratios have a higher content in the lung after PEG modification. We also found MSNs are mainly excreted by urine and feces, and the clearance rate of MSNs is primarily dependent on the particle shape, where short-rod MSNs have a more rapid clearance rate than long-rod MSNs in both excretion routes. Hematology, serum biochemistry, and histopathology results indicate that MSNs would not cause significant toxicity in vivo, but there is potential induction of biliary excretion and glomerular filtration dysfunction. These findings may provide useful information for the design of nanoscale delivery systems and the environmental fate of nanoparticles.
In spite of significant advantages exhibiting in the applications of silicon dioxide particles in biological and medicine fields, their adverse effects still remain a big concern. Herein monodisperse spherical SiO(2) particles with diameters of 80 nm and 500 nm were used to study their interactions with human dermal fibroblasts. Both the particles were readily internalized into the fibroblasts within a short time. The 500 nm particles were taken up in a larger amount through macropinocytosis and clathrin-mediated endocytosis pathways, whereas uptake of the 80 nm SiO(2) particles was mediated corporately by macropinocytosis, clathrin-mediated and caveolae-mediated endocytosis. The particles mainly dispersed in the cytoplasm or resided within the lysosomal vesicles, but could not enter into the cell nucleus within 24 h culture in vitro. Treatment with the 80 nm SiO(2) particles caused apparently decrease of cell viability and also weakened the mitochondrial membrane potential. Further experiments demonstrated that the cell adhesion and migration were greatly affected by uptake of the SiO(2) particles regardless of their size. RT-PCR results indicated down regulation of the mRNA expression of adhesion relevant genes, i.e. fibronectin, laminin and focal adhesion kinase (FAK).
Deep bone defects are caused by the progression of periodontal disease, which breaks down bone and connective tissue that hold teeth in place. In this case, a 37-year-old male patient presented a deep bone defect with advanced periodontal disease around an upper canine. Medical-grade calcium sulfate was mixed with demineralized freeze-dried bone allograft and used to repair and regenerate the defect. Analysis of the radiographs at the 5-month time point showed the bone had completely regenerated.
Stress or heat shock proteins (HSPs) 70 and 90 are powerful chaperones whose expression is induced in response to a wide variety of physiological and environmental insults. These proteins have different functions depending on their intracellular or extracellular location. Intracellular HSPs have a protective function. They allow the cells to survive potentially lethal conditions. The cytoprotective functions of HSPs can largely be explained by their anti-apoptotic properties. HSP70 and HSP90 can directly interact with different proteins of the tightly regulated programmed cell death machinery and thereby block the apoptotic process at distinct key points. In cancer cells, where the expression of HSP70 and/or HSP90 is frequently abnormally high, they participate in oncogenesis and in resistance to chemotherapy. Therefore, the inhibition of HSPs has become an interesting strategy in cancer therapy. In contrast to intracellular HSPs, extracellularly located or membrane-bound HSPs mediate immunological functions. They can elicit an immune response providing a link between innate and adaptive immune systems. In cancer, most immunotherapeutical approaches based on extracellular HSPs exploit their carrier function for immunogenic peptides. This review will focus on the roles of HSP70 and HSP90 in apoptosis and in innate immunity and how these functions are being exploited in cancer therapy.
A diverse array of environmental factors contributes to the overall control of stem cell activity. In particular, new data continue to mount on the influence of the extracellular matrix (ECM) on stem cell fate through physical interactions with cells, such as the control of cell geometry, ECM geometry/topography at the nanoscale, ECM mechanical properties, and the transmission of mechanical or other biophysical factors to the cell. Here, we review some of the physical processes by which cues from the ECM can influence stem cell fate, with particular relevance to the use of stem cells in tissue engineering and regenerative medicine.
A study was conducted to demonstrate the synthesis of monodisperse mesoporous silica nanoparticle (MSN) suspensions and investigate the effect of nanoparticle size on cell uptake. The MSNs were synthesized by adjusting the pH of the reaction medium, leading to a series of MSNs with uniform size ranging from 30-280 nm. The physical properties of the MSNs were characterized with various methods, such as nitrogen adsorption-desorption, transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). The particle size effect on the cell uptake efficiency with human cervical cancer cells and cellular uptake of MSNs of various sizes were investigated by confocal laser scanning microscopy (CLSM). The uptake efficiencies were determined by inductively coupled plasma mass spectrometry (ICP-MS) analysis of total silicon content.
Calcium sulfate (CS) has enjoyed a longer history of clinical use than most currently available biomaterials. It is well-tolerated when used to fill bone defects and undergoes rapid and complete resorption without eliciting a significant inflammatory response. The raw material from which it is made is relatively inexpensive and abundant. In addition, CS can be used as a vehicle to deliver antibiotics, pharmacologic agents, and growth factors. It has found wide use in orthopedics and dentistry, and has been used in a variety of clinical applications, including the periodontal defect repair, the treatment of osteomyelitis, sinus augmentation, and as an adjunct to dental implant placement. Despite these advantages, the material has not enjoyed the popularity of many other regenerative materials, although there has been a recent resurgence of interest in the material. This review examines the properties and clinical applications of CS, with an emphasis on dental applications of the material. Limitations of the material are discussed as well as suggestions for future research.
Nanoparticles are an emerging class of functional materials defined by size-dependent properties. Application fields range from medical imaging, new drug delivery technologies to various industrial products. Due to the expanding use of nanoparticles, the risk of human exposure rapidly increases and reliable toxicity test systems are urgently needed. Currently, nanoparticle cytotoxicity testing is based on in vitro methods established for hazard characterization of chemicals. However, evidence is accumulating that nanoparticles differ largely from these materials and may interfere with commonly used test systems. Here, we present an overview of current in vitro toxicity test methods for nanoparticle risk assessment and focus on their limitations resulting from specific nanoparticle properties. Nanoparticle features such as high adsorption capacity, hydrophobicity, surface charge, optical and magnetic properties, or catalytic activity may interfere with assay components or detection systems, which has to be considered in nanoparticle toxicity studies by characterization of specific particle properties and a careful test system validation. Future studies require well-characterized materials, the use of available reference materials and an extensive characterization of the applicability of the test methods employed. The resulting challenge for nanoparticle toxicity testing is the development of new standardized in vitro methods that cannot be affected by nanoparticle properties.
The progress of using gadolinium (Gd)-based nanoparticles in cellular tracking lags behind that of superparamagnetic iron oxide (SPIO) nanoparticles in magnetic resonance imaging (MRI). Here, dual functional Gd-fluorescein isothiocyanate mesoporous silica nanoparticles (Gd-Dye@MSN) that possess green fluorescence and paramagnetism are developed in order to evaluate their potential as effective T1-enhancing trackers for human mesenchymal stem cells (hMSCs). hMSCs are labeled efficiently with Gd-Dye@MSN via endocytosis. Labeled hMSCs are unaffected in their viability, proliferation, and differentiation capacities into adipocytes, osteocytes, and chondrocytes, which can still be readily MRI detected. Imaging, with a clinical 1.5-T MRI system and a low incubation dosage of Gd, low detection cell numbers, and short incubation times is demonstrated on both loaded cells and hMSC-injected mouse brains. This study shows that the advantages of biocompatibility, durability, high internalizing efficiency, and pore architecture make MSNs an ideal vector of T1-agent for stem-cell tracking with MRI.
The causes of ovarian cancer are unknown. The increased incidence in industrialised countries suggests an environmental influence. Epidemiological, experimental,. and clinical data seem to link asbestos and talc with ovarian cancer. Direct passage of talc or asbestos-contaminated talc through the female reproductive tract to the ovarian surface may play an ætiological role. Further systematic evaluation of talc and asbestos as ovarian carcinogens is needed.
Using a method that allowed the reconstruction of simplified living human skin in vitro, we investigated the effects of collagen texture and dermal fibroblasts on epidermal growth. Like in vivo skin, our in vitro model comprised two tissues: a dermal equivalent and an overlying epidermis. It permitted measurement of epidermal growth and therefore evaluation of the effect of the dermal equivalent on this growth.
Epidermal growth was enhanced when the collagen matrix had previously been reorganized by fibroblasts, and was greatest when living fibroblasts persisted in this matrix. On cell-free collagen gel and on collagen matrices containing dead fibroblasts, epidermal growth increased when the medium was conditioned by fibroblasts grown in monolayers.
We conclude chat the function of the fibroblasts is not wily to synthesize and degrade the extracellular matrix, but also to regulate epidermalization; on the one hand by remodeling the collagen fibers, and on the other by secreting diffusible factors that promote epidermal growth. These results underline the importance of fibroblasts in dermo-epidermal inter- actions, and show that the skin equivalent culture model provides a way to quantitatively study these interactions.
An in vitro study of the biologic responses of surface-modified and native silica and kaolin was made to provide comparative information on the suppression of cytotoxicity by pulmonary surfactant. The release of alveolar macrophage cytoplasmic enzyme, lactate dehydrogenase (LDH), and lysosomal enzymes beta-N-acetylglucosaminidase (beta-NAG) and beta-glucuronidase (beta-GLUC) and sheep blood-cell hemolysis were monitored as indicators of cell membrane damage and cytotoxicity. Surface modification of silica and kaolin with dipalmitoyl lecithin (DPL) resulted in complete abrogation of cytotoxicity of both minerals. These findings indicate that surface modification of minerals with different adsorption properties by pulmonary surfactant generally lessens their prompt adverse effects.
The inhalation of china clay dust by man can cause pneumoconiosis. In an attempt to identify the factors responsible the cytotoxicity in vitro of china clay dust towards mouse peritoneal macrophages was examined. Respirable dusts collected at china clay drying plants were cytotoxic towards the cells. This activity was caused by kaolinite (the major mineral in china clay) and was not due to the presence of ancillary minerals. The cytotoxicity of kaolinite was not due to particle morphology and the positively charged edges of the mineral contributed only slightly to cytotoxicity. An electron microscope study showed that macrophages phagocytosed PVPNO-coated kaolinite particles indicating that the low cytotoxicity of these particles was not due to poor phagocytosis. Residence of china clay in rat lungs appeared to reduce its cytotoxicity. It was concluded that the cytotoxicity of kaolinite was probably related to the proposed amorphous silica-rich gel coating on the particles. The relevance of the findings in vitro to the effects in vivo of china clay is discussed.
Treatment of symptomatic carcinomatous pleural effusions is primarily directed at local palliation with a wide variety of sclerosing agents, of which talc is considered to be the most successful. The mechanism whereby talc achieves this effect is unknown. The objective of this study was to investigate whether talc stimulates pleural mesothelial cells (PMC) to release C-X-C and/or C-C chemokines and express adhesion molecules that initiate and amplify the inflammatory process in the pleural space. When PMC were challenged with talc in vitro, interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) levels were increased (p < 0.001) both at the protein and the mRNA level as compared with unstimulated cultures. Talc-stimulated PMC culture supernatant showed chemotactic activity for neutrophils and monocytes. The chemotactic activity of PMC culture supernatant was blocked by 44.2% with IL-8-specific antibody and by 55.7% with MCP-1-specific antibody, demonstrating that PMC-derived chemokines are bioactive. Talc also enhanced intercellular adhesion molecule-1 (ICAM-1) expression in PMC. The data demonstrate that talc stimulates PMC to release chemokines and express adhesion molecules that may play a critical role in pleurodesis.
The protein adsorption behavior of thin films of calcium phosphate (CaP) bioceramic and titanium (Ti) was studied in this research. The thin films were produced with an ion beam sputter deposition technique using targets of hydroxyapatite (HA), fluorapatite (FA) and titanium (Ti). Fourier transform infrared spectroscopy (FTIR) with attenuated total internal reflectance (ATR) was used to evaluate protein adsorption on these surfaces. This study showed that surface composition and structure influenced the kinetics of protein adsorption and the structure of adsorbed protein. CaP surfaces adsorbed greater amount of protein than the Ti surface, and caused more alteration of the structure of adsorbed BSA than did the Ti surface. The differences in protein adsorption behavior could result in very different initial cellular behavior on CaP and Ti implant surfaces.
The review focuses on a widely-observed morphological phenomenon, a unique class of cytoplasmic vacuolation, found in cultured (mammalian) cells. This vacuolation is quite distinct from autophagosomal and heterophagosomal, i.e. excessive lysosomal vacuolation, and occurs in most cell types spontaneously or via a wide range of inductive stimuli. Apart from vacuolation arising artefactually (usually due to poor fixation), spontaneous vacuolation occurs in individual or small clusters of cultured cells without apparent change in their local environment, while neighbouring cells remain completely unaffected. Since spontaneous vacuolation is unpredictable, the process of vacuolation--or 'vacuolisation'--('Vacuolation' is the state of being with vacuoles; 'vacuolisation' therefore implies the process of becoming vacuolated. However, only the quicker term vacuolation will be used throughout this review to refer to the process of vacuole development.) induced experimentally, and hence relatively reproducibly by a range of substances and disturbances, offers an experimental approach which should give further insight into its physiology and pathophysiology. Unfortunately, our knowledge here remains woefully inadequate compared with the purely morphological aspects of the phenomenon. Vacuolation following disturbances could have an underlying common mechanism; however, a review of the literature suggests that this is not the case, and that it occurs via several different pathways, involving many different cell organelles and structures. All cells appear to retain the capacity to vacuolate for some physiological purpose, and it can be a permanent feature in many cell types, particularly 'lower' organisms and plants. Vacuolation in cells is generally seen as an adaptive physiological response, presumably for 'damage limitation', but very little is known about the intracellular homeostatic mechanisms which operate to restore the status quo. Where damage limitation fails, cells usually die quickly, but no clear evidence has been found that this is in any way 'programmed'. It is argued that the demise which occurs via the vacuolation route may, in fact, be a distinct form of cell death which is difficult to fit into the conventional lytic and apoptotic modes.