Exposure effects of endotoxin-free titanium-based wear particles to human osteoblasts

Titanium-based materials are widely employed by the biomedical industry in orthopedic and dental implants. However, when placed into the human body, these materials are highly susceptible to degradation processes, such as corrosion, wear, and tribocorrosion. As a consequence, metallic ions or particles (debris) may be released, and although several studies have been conducted in recent years to better understand the effects of their exposure to living cells, a consensual opinion has not yet been obtained. In this work, we produced metallic based wear particles by tribological tests carried out on Ti-6Al-4V and Ti-15Zr-15Mo alloys. They were posteriorly physicochemically characterized according to their crystal structure, size, morphology, and chemical composition and compared to Ti-6Al-4V commercially available particles. Finally, adsorbed endotoxins were removed (by applying a specific thermal treatment) and endotoxin-free particles were used in cell experiments to evaluate effects of their exposure to human osteoblasts (MG-63 and HOb), namely cell viability/metabolism, proinflammatory cytokine production (IL-6 and PGE2), and susceptibility to internalization processes. Our results indicate that tribologically-obtained wear particles exhibit fundamental differences in terms of size (smaller) and morphology (irregular shapes and rough surfaces) when compared to the commercial ones. Consequently, both Ti-6Al-4V and Ti-15Zr-15Mo particles were able to induce more pronounced effects on cell viability (decrease) and cytokine production (increase) than did Ti-6Al-4V commercial particles. Furthermore, both types of wear particles penetrated osteoblast membranes and were internalized by the cells. Influences on cytokine production by endotoxins were also demonstrated.This work was supported by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP (2015/50280-5 and 2017/24300-4), Fundacao para a Ciencia e Tecnologia - FCT (UID/EEA/04436/2013), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - CAPES (Finance Code 0001), FCT/CAPES Joint Research Project (99999.008666/2014-08), FCT COMPETE 2020 (POCI-01-0145-FEDER-006941 and POCI-01-0145-FEDER-007265) and M-ERA-NET (0001/2015)

Nanoparticle-Decorated Erythrocytes Reveal That Particle Size Controls the Extent of Adsorption, Cell Shape, and Cell Deformability

Unraveling the interaction of nanoparticles with living cells is fundamental for nanomedicine and nanotoxicology. Erythrocytes are abundant and serve as model cells with well-characterized properties. Quantitative experiments addressing the binding of carboxylated polystyrene nanoparticles to human erythrocytes reveal saturated adsorption with only sparse (∼2%) coverage of the cell membrane by partial-wrapped nanoparticles. The independence of the adsorbed area on particle size suggests a restricted number of adhesive sites on the membrane. Using a continuum membrane model combined with nanoparticle–membrane adhesion mediated by receptor–ligand bonds, we predict high bond energies and low receptor densities for partial-wrapped particles. With the help of computer simulations, we determine sets of receptor densities, receptor diffusion coefficients, minimal numbers of bound receptors required for multivalent binding, and maximal possible numbers of bound receptors that reproduce the experimental nanoparticle adsorption data. Nanoparticle decoration of erythrocytes leads to shape transformations and reduced cell deformability. We quantitatively characterize and interpret erythrocyte shape and deformability changes. The shape changes also offer insights into the modification of the mechanical properties of other mammalian cell membranes by adhered nanoparticles. A potential application of nanoparticle-loaded erythrocytes is retarded targeted drug delivery with a long lifetime of the particles in the blood circulation

Predictive Toxicology of Cobalt Nanoparticles and Ions: Comparative In Vitro Study of Different Cellular Models Using Methods of Knowledge Discovery from Data.

International audienc

Predictive Toxicology of cobalt ferrite nanoparticles: comparative in-vitro study of different cellular models using methods of knowledge discovery from data.

International audienceBACKGROUND: Cobalt-ferrite nanoparticles (Co-Fe NPs) are attractive for nanotechnology-based therapies. Thus, exploring their effect on viability of seven different cell lines representing different organs of the human body is highly important. METHODS: The toxicological effects of Co-Fe NPs were studied by in-vitro exposure of A549 and NCIH441 cell-lines (lung), precision-cut lung slices from rat, HepG2 cell-line (liver), MDCK cell-line (kidney), Caco-2 TC7 cell-line (intestine), TK6 (lymphoblasts) and primary mouse dendritic-cells. Toxicity was examined following exposure to Co-Fe NPs in the concentration range of 0.05 -1.2 mM for 24 and 72 h, using Alamar blue, MTT and neutral red assays. Changes in oxidative stress were determined by a dichlorodihydrofluorescein diacetate based assay. Data analysis and predictive modeling of the obtained data sets were executed by employing methods of Knowledge Discovery from Data with emphasis on a decision tree model (J48). RESULTS: Different dose-response curves of cell viability were obtained for each of the seven cell lines upon exposure to Co-Fe NPs. Increase of oxidative stress was induced by Co-Fe NPs and found to be dependent on the cell type. A high linear correlation (R2=0.97) was found between the toxicity of Co-Fe NPs and the extent of ROS generation following their exposure to Co-Fe NPs. The algorithm we applied to model the observed toxicity belongs to a type of supervised classifier. The decision tree model yielded the following order with decrease of the ranking parameter: NP concentrations (as the most influencing parameter), cell type (possessing the following hierarchy of cell sensitivity towards viability decrease: TK6 > Lung slices > NCIH441 > Caco-2 = MDCK > A549 > HepG2 = Dendritic) and time of exposure, where the highest-ranking parameter (NP concentration) provides the highest information gain with respect to toxicity. The validity of the chosen decision tree model J48 was established by yielding a higher accuracy than that of the well-known "naive bayes" classifier. CONCLUSIONS: The observed correlation between the oxidative stress, caused by the presence of the Co-Fe NPs, with the hierarchy of sensitivity of the different cell types towards toxicity, suggests that oxidative stress is one possible mechanism for the toxicity of Co-Fe NPs