Improving Quality in Nanoparticle-Induced Cytotoxicity Testing by a Tiered Inter-Laboratory Comparison Study.

The quality and relevance of nanosafety studies constitute major challenges to ensure their key role as a supporting tool in sustainable innovation, and subsequent competitive economic advantage. However, the number of apparently contradictory and inconclusive research results has increased in the past few years, indicating the need to introduce harmonized protocols and good practices in the nanosafety research community. Therefore, we aimed to evaluate if best-practice training and inter-laboratory comparison (ILC) of performance of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay for the cytotoxicity assessment of nanomaterials among 15 European laboratories can improve quality in nanosafety testing.

Pan-European inter-laboratory studies on a panel of in vitro cytotoxicity and pro-inflammation assays for nanoparticles.

The rapid development of nanotechnologies and increased production and use of nanomaterials raise concerns about their potential toxic effects for human health and environment. To evaluate the biological effects of nanomaterials, a set of reliable and reproducible methods and development of standard operating procedures (SOPs) is required. In the framework of the European FP7 NanoValid project, three different cell viability assays (MTS, ATP content, and caspase-3/7 activity) with different readouts (absorbance, luminescence and fluorescence) and two immune assays (ELISA of pro-inflammatory cytokines IL1-β and TNF-α) were evaluated by inter-laboratory comparison.

Physicochemical and toxicological evaluation of silica nanoparticles suitable for food and consumer products collected by following the EC recommendation.

Specific information about the particle size distribution, agglomeration state, morphology, and chemical composition of four silica samples, used as additives in food and in personal care products, were achieved with a combination of analytical techniques. The combined use of differential centrifugal sedimentation (DCS), sedimentation field flow fractionation (SdFFF), and scanning and transmission electron microscopy (SEM and TEM) allows to classify the water dispersed samples as "nanomaterials" according to the EC definition. The mechanical stirring and the ultrasound treatment were compared as dispersion methods.

Role of p38MAPK and oxidative stress in copper-induced senescence.

In the present work, we indicate that copper is involved in the senescence of human diploid fibroblasts and we describe mechanisms to explain it. Using different techniques, we show for the first time an accumulation of copper in cells during replicative senescence. This accumulation seems to be co-localized with lipofuscin.

Copper(II) oxide nanoparticles penetrate into HepG2 cells, exert cytotoxicity via oxidative stress and induce pro-inflammatory response.

The potential toxic effects of two types of copper(II) oxide (CuO) nanoparticles (NPs) with different specific surface areas, different shapes (rod or spheric), different sizes as raw materials and similar hydrodynamic diameter in suspension were studied on human hepatocarcinoma HepG2 cells. Both CuO NPs were shown to be able to enter into HepG2 cells and induce cellular toxicity by generating reactive oxygen species. CuO NPs increased the abundance of several transcripts coding for pro-inflammatory interleukins and chemokines.

Differential toxicity of copper (II) oxide nanoparticles of similar hydrodynamic diameter on human differentiated intestinal Caco-2 cell monolayers is correlated in part to copper release and shape.

The potential toxic effects of copper oxide (CuO) nanoparticles (NPs) were studied on differentiated Caco-2 cell monolayers, a classical in vitro model of human small intestine epithelium. Two types of CuO NPs, with different specific surface area, different sizes as raw material but the same hydrodynamic diameter in suspension, differentially disturbed the monolayer integrity, were cytotoxic and triggered an increase of the abundance of several transcripts coding for pro-inflammatory cytokines and chemokines. Specific surface area was not a major variable explaining the increased toxicity when intestinal epithelium is exposed to rod-shaped CuO NPs, compared with spherical CuO NPs.

Validation of the calibrated thrombin generation test (cTGT) as the reference assay to evaluate the procoagulant activity of nanomaterials.

We validated a preclinical toxicological screening assay and provided guidelines to evaluate the potential impact of nanoparticles (NPs) on blood coagulation. Five NPs with various physicochemical properties were studied using several existing methods of clotting times and thrombin generation assays in human normal pool plasma. In both recalcification clotting time (RCT) and calibrated thrombin generation test (cTGT), the NPs exhibited procoagulant activity (SiO₂ ≥ SiC ≥ TiC > CuO > CB) but cTGT was more sensitive and relevant than RCT.

Casein kinase 2 inhibition decreases hypoxia-inducible factor-1 activity under hypoxia through elevated p53 protein level.

HIF-1 (hypoxia-inducible factor-1) is the main transcription factor involved in the adaptation of cells to hypoxia. In addition to regulation of HIF-1alpha protein level, HIF-1 activity is also enhanced by several pathways involving asparagine hydroxylation and phosphorylation. Here, we investigated the relationship between casein kinase 2 (CK2), p53 and HIF-1.

Caspase activation precedes PTP opening in TNF-alpha-induced apoptosis in L929 cells.

In this work, we studied the apoptotic pathway in murine fibrosarcoma cells L929 exposed to tumor necrosis factor alpha (TNF-alpha). DNA fragmentation, activation of caspases, cytochrome c release and poly (ADP-ribose) polymerase cleavage were demonstrated. We showed that the proapoptotic proteins Bid and Bax as well as caspase 8 are involved in the initiation of this apoptotic pathway triggered by TNF-alpha.

Hypoxia-inducible factor-1-dependent overexpression of myeloid cell factor-1 protects hypoxic cells against tert-butyl hydroperoxide-induced apoptosis.

Increased levels of Mcl-1 (myeloid cell factor-1) have been reported in several cancers, suggesting an important role played by Mcl-1 in cancer cell survival. Mcl-1 is an anti-apoptotic protein shown to delay or block apoptosis. In this work, using semiquantitative immunofluorescence, real-time PCR, and RNase protection assay, an increase in Mcl-1 expression was detected in hepatoma HepG2 cells incubated under hypoxia or in the presence of cobalt chloride.

Hypoxia and CoCl2 protect HepG2 cells against serum deprivation- and t-BHP-induced apoptosis: a possible anti-apoptotic role for HIF-1.

Hypoxia inducible factor-1 (HIF-1) is the main transcriptional factor activated by hypoxia. Besides the well-described role assigned to HIF-1 in the adaptation of cells to hypoxia, different recent data describe a possible role for HIF-1 in the modulation of apoptosis. However, this precise role is not yet clearly understood.

Mitochondria permeability transition-dependent tert-butyl hydroperoxide-induced apoptosis in hepatoma HepG2 cells.

Tert-butyl hydroperoxide (t-BHP) has been demonstrated to induce apoptosis in hepatoma cell line HepG2, but poor data were available on the signaling pathway initiated by t-BHP. In this work, we studied in details the apoptotic pathways induced in HepG2 cells by t-BHP. DNA fragmentation, activation of caspases and cytochrome c release were demonstrated.

Soluble factors released by virus specific activated cytotoxic T-lymphocytes induce apoptotic death of astroglioma cell lines.

Astrocytomas and astrogliomas represent the most common types of primary tumors in human central nervous system and are associated with high mortality due to the absence of efficient therapy. Here we demonstrate that, upon antigen-specific activation, cytotoxic T-lymphocytes (CTLs) secrete products that inhibit proliferation and induce apoptosis in a significant proportion of astroglioma cell lines. This effect is tumor specific in that normal cultured astrocytes do not develop apoptotic changes upon exposure to supernatant of activated CTLs.

CoCl2, a chemical inducer of hypoxia-inducible factor-1, and hypoxia reduce apoptotic cell death in hepatoma cell line HepG2.

HIF-1 (hypoxia-inducible factor-1) is the major transcription factor that is specifically activated during hypoxia. This transcription factor is composed of two subunits: HIF-1alpha and ARNT (aryl hydrocarbon receptor nuclear translocator). ARNT is constitutively expressed, whereas HIF-1alpha is targeted to proteasome degradation by ubiquitination during normoxia.

Is HIF-1alpha a pro- or an anti-apoptotic protein?

Hypoxia-inducible factor-1 (HIF-1) is the major transcription factor specifically activated by hypoxia. It induces the expression of different genes whose products play an adaptive role for hypoxic cells and tissues. Besides these protective responses, HIF-1 and/or hypoxia have also been shown to be either anti-apoptotic or pro-apoptotic, according to the cell type and experimental conditions.