Printer center nanoparticles alter the DNA repair capacity of human bronchial airway epithelial cells.

Nano-enabled, toner-based printing equipment emit nanoparticles during operation. The bioactivity of these nanoparticles as documented in a plethora of published toxicological studies raises concerns about their potential health effects. These include pro-inflammatory effects that can lead to adverse epigenetic alterations and cardiovascular disorders in rats. At the same time, their potential to alter DNA repair pathways at realistic doses remains unclear. In this study, size-fractionated, airborne particles from a printer center in Singapore were sampled and characterized. The PM0.1 size fraction (particles with an aerodynamic diameter less than 100 nm) of printer center particles (PCP) were then administered to human lung adenocarcinoma (Calu-3) or lymphoblastoid (TK6) cells. We evaluated plasma membrane integrity, mitochondrial activity, and intracellular reactive oxygen species (ROS) generation. Moreover, we quantified DNA damage and alterations in the cells' capacity to repair 6 distinct types of DNA lesions. Results show that PCP altered the ability of Calu-3 cells to repair 8oxoG:C lesions and perform nucleotide excision repair, in the absence of acute cytotoxicity or DNA damage. Alterations in DNA repair capacity have been correlated with the risk of various diseases, including cancer, therefore further genotoxicity studies are needed to assess the potential risks of PCP exposure, at both occupational settings and at the end-consumer level.

Toxicity, uptake, and nuclear translocation of ingested micro-nanoplastics in an in vitro model of the small intestinal epithelium.

Despite mounting evidence of increasing micro- and nanoplastics (MNPs) in natural environments, food, and drinking water, little is known of the potential health hazards of MNPs ingestion. We assessed toxicity and uptake of environmentally relevant MNPs in an in vitro small intestinal epithelium (SIE). Test MNPs included 25 and 1000 nm polystyrene (PS) microspheres (PS25 and PS1K); 25, 100, and 1000 nm carboxyl modified PS spheres (PS25C, PS100C, and PS1KC), and secondary MNPs from incinerated polyethylene (PEI). MNPs were subjected to 3-phase digestion to mimic transformations in the gastrointestinal tract (GIT) and digestas applied to the SIE. Carboxylated MNPs significantly reduced viability and increased permeability to 3 kD dextran. Uptake of carboxyl PS materials was size dependent, with significantly greater uptake of PS25C. Fluorescence confocal imaging showed some PS25C agglomerates entering cells independent of endosomes (suggesting diffusion), others within actin shells (suggesting phagocytosis), and many free within the epithelial cells, including agglomerates within nuclei. Pre-treatment with the dynamin inhibitor Dyngo partially reduced PS25 translocation, suggesting a potential role for endocytosis. These findings suggest that ingestion exposures to MNPs could have serious health consequences and underscore the urgent need for additional detailed studies of the potential hazards of ingested MNPs.

Oxidized carbon black nanoparticles induce endothelial damage through C-X-C chemokine receptor 3-mediated pathway.

Oxidation of engineered nanomaterials during application in various industrial sectors can alter their toxicity. Oxidized nanomaterials also have widespread industrial and biomedical applications. In this study, we evaluated the cardiopulmonary hazard posed by these nanomaterials using oxidized carbon black (CB) nanoparticles (CBox) as a model particle. Particle surface chemistry was characterized by X-ray photo electron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). Colloidal characterization and in vitro dosimetry modeling (particle kinetics, fate and transport modeling) were performed. Lung inflammation was assessed following oropharyngeal aspiration of CB or oxidized CBox particles (20 µg per mouse) in C57BL/6J mice. Toxicity and functional assays were also performed on murine macrophage (RAW 264.7) and endothelial cell lines (C166) with and without pharmacological inhibitors. Oxidant generation was assessed by electron paramagnetic resonance spectroscopy (EPR) and via flow cytometry. Endothelial toxicity was evaluated by quantifying pro-inflammatory mRNA expression, monolayer permeability, and wound closure. XPS and FTIR spectra indicated surface modifications, the appearance of new functionalities, and greater oxidative potential (both acellular and in vitro) of CBox particles. Treatment with CBox demonstrated greater in vivo inflammatory potentials (lavage neutrophil counts, secreted cytokine, and lung tissue mRNA expression) and air-blood barrier disruption (lavage proteins). Oxidant-dependent pro-inflammatory signaling in macrophages led to the production of CXCR3 ligands (CXCL9,10,11). Conditioned medium from CBox-treated macrophages induced significant elevation in endothelial cell pro-inflammatory mRNA expression, enhanced monolayer permeability and impairment of scratch healing in CXCR3 dependent manner. In summary, this study mechanistically demonstrated an increased biological potency of CBox particles and established the role of macrophage-released chemical mediators in endothelial damage.

High-Throughput Screening Platform for Nanoparticle-Mediated Alterations of DNA Repair Capacity.

The potential genotoxic effects of engineered nanomaterials (ENMs) may occur through the induction of DNA damage or the disruption of DNA repair processes. Inefficient DNA repair may lead to the accumulation of DNA lesions and has been linked to various diseases, including cancer. Most studies so far have focused on understanding the nanogenotoxicity of ENM-induced damages to DNA, whereas the effects on DNA repair have been widely overlooked. The recently developed fluorescence multiplex-host-cell reactivation (FM-HCR) assay allows for the direct quantification of multiple DNA repair pathways in living cells and offers a great opportunity to address this methodological gap. Herein an FM-HCR-based method is developed to screen the impact of ENMs on six major DNA repair pathways using suspended or adherent cells. The sensitivity and efficiency of this DNA repair screening method were demonstrated in case studies using primary human small airway epithelial cells and TK6 cells exposed to various model ENMs (CuO, ZnO, and Ga2O3) at subcytotoxic doses. It was shown that ENMs may inhibit nucleotide-excision repair, base-excision repair, and the repair of oxidative damage by DNA glycosylases in TK6 cells, even in the absence of significant genomic DNA damage. It is of note that the DNA repair capacity was increased by some ENMs, whereas it was suppressed by others. Overall, this method can be part of a multitier, in vitro hazard assessment of ENMs as a functional, high-throughput platform that provides insights into the interplay of the properties of ENMs, the DNA repair efficiency, and the genomic stability.

Inflammation Increases Susceptibility of Human Small Airway Epithelial Cells to Pneumonic Nanotoxicity.

Exposure to inhaled anthropogenic nanomaterials (NM) with dimension <100 nm has been implicated in numerous adverse respiratory outcomes. Although studies have identified key NM physiochemical determinants of pneumonic nanotoxicity, the complex interactive and cumulative effects of NM exposure, especially in individuals with preexisting inflammatory respiratory diseases, remain unclear. Herein, the susceptibility of primary human small airway epithelial cells (SAEC) exposed to a panel of reference NM, namely, CuO, ZnO, mild steel welding fume (MSWF), and nanofractions of copier center particles (Nano-CCP), is examined in normal and tumor necrosis factor alpha (TNF-α)-induced inflamed SAEC. Compared to normal SAEC, inflamed cells display an increased susceptibility to NM-induced cytotoxicity by 15-70% due to a higher basal level of intracellular reactive oxygen species (ROS). Among the NM screened, ZnO, CuO, and Nano-CCP are observed to trigger an overcompensatory response in normal SAEC, resulting in an increased tolerance against subsequent oxidative insults. However, the inflamed SAEC fails to adapt to the NM exposure due to an impaired nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated cytoprotective response. The findings reveal that susceptibility to pulmonary nanotoxicity is highly dependent on the interplay between NM properties and inflammation of the alveolar milieu.

Human brain microvascular endothelial cell pairs model tissue-level blood-brain barrier function.

The blood-brain barrier plays a critical role in delivering oxygen and nutrients to the brain while preventing the transport of neurotoxins. Predicting the ability of potential therapeutics and neurotoxicants to modulate brain barrier function remains a challenge due to limited spatial resolution and geometric constraints offered by existing in vitro models. Using soft lithography to control the shape of microvascular tissues, we predicted blood-brain barrier permeability states based on structural changes in human brain endothelial cells. We quantified morphological differences in nuclear, junction, and cytoskeletal proteins that influence, or indicate, barrier permeability. We established a correlation between brain endothelial cell pair structure and permeability by treating cell pairs and tissues with known cytoskeleton-modulating agents, including a Rho activator, a Rho inhibitor, and a cyclic adenosine monophosphate analog. Using this approach, we found that high-permeability cell pairs showed nuclear elongation, loss of junction proteins, and increased actin stress fiber formation, which were indicative of increased contractility. We measured traction forces generated by high- and low-permeability pairs, finding that higher stress at the intercellular junction contributes to barrier leakiness. We further tested the applicability of this platform to predict modulations in brain endothelial permeability by exposing cell pairs to engineered nanomaterials, including gold, silver-silica, and cerium oxide nanoparticles, thereby uncovering new insights into the mechanism of nanoparticle-mediated barrier disruption. Overall, we confirm the utility of this platform to assess the multiscale impact of pharmacological agents or environmental toxicants on blood-brain barrier integrity.

Metals distribution in colorectal biopsies: New insight on the elemental fingerprint of tumour tissue.

BACKGROUND: Some studies have linked colorectal cancer to metal exposure. AIMS: Our objective was to evaluate the element distribution in colorectal adenocarcinoma biopsies, adjacent non-tumour tissues, and healthy controls. METHODS: The study is a case-control study which compared the element distribution in colon biopsies from two groups of patients: with colorectal cancer (2 types of samples: colorectal cancer biopsies and adjacent non-tumour tissues) and healthy controls. Fifteen metal concentrations (Aluminium, Boron, Cadmium, Chromium, Copper, Iron, Magnesium, Manganese, Nickel, Lead, Selenium, Silicon, Titanium, Vanadium, and Zinc) were quantified by using inductively coupled plasma atomic emission spectrometry. RESULTS: 104 patients were included: 76 in the colorectal cancer group, 28 in the healthy control group. Among the 15 elements analyzed, only boron, chromium, zinc, silicon and magnesium were found at clearly detectable concentrations. Colorectal tumour biopsies had significantly higher concentrations of magnesium as compared to adjacent non-tumour or healthy tissues. Zinc concentration followed the same trend but differences were not statistically significant. In addition, concentration of silicon was higher in colorectal cancer tissue than in healthy non-cancer tissue, while chromium was mostly found in adjacent non-tumour tissue. CONCLUSION: Magnesium, chromium, zinc and silicon were found in noteworthy concentrations in colorectal tumour. Their potential role in colorectal carcinogenesis should be explored.

Purified graphene oxide dispersions lack in vitro cytotoxicity and in vivo pathogenicity.

Prompted by the excitement from the description of single layer graphene, increased attention for potential applications in the biomedical field has been recently placed on graphene oxide (GO). Determination of the opportunities and limitations that GO offers in biomedicine are particularly prone to inaccuracies due to wide variability in the preparation methodologies of GO material in different laboratories, that results in significant variation in the purity of the material and the yield of the oxidation reactions, primarily the Hummers method used. Herein, the fabrication of highly pure, colloidally stable, and evenly dispersed GO in physiologically-relevant aqueous buffers in comparison to conventional GO is investigated. The purified GO material is thoroughly characterized by a battery of techniques, and is shown to consist of single layer GO sheets of lateral dimensions below 500 nm. The cytotoxic impact of the GO in vitro and its inflammation profile in vivo is investigated. The purified GO prepared and characterized here does not induce significant cytotoxic responses in vitro, or inflammation and granuloma formation in vivo following intraperitoneal injection. This is one of the initial steps towards determination of the safety risks associated with GO material that may be interacting with living tissue.

Optimizing Druggability through Liposomal Formulations: New Approaches to an Old Concept.

Developing innovative delivery strategies remains an ongoing task to improve both efficacy and safety of drug-based therapy. Nanomedicine is now a promising field of investigation, rising high expectancies for treating various diseases such as malignancies. Putting drugs into liposome is an old story that started in the late 1960s. Because of the near-total biocompatibility of their lipidic bilayer, liposomes are less concerned with the safety issue related to the possible long-term accumulation in the body of most nanoobjects currently developed in nanomedicine. Additionally, novel techniques and recent efforts to achieve better stability (e.g., through sheddable coating), combined with a higher selectivity towards target cells (e.g., by anchoring monoclonal antibodies or incorporating phage fusion protein), make new liposomal drugs an attractive and challenging opportunity to improve clinical outcome in a variety of disease. This review covers the physicochemistry of liposomes and the recent technical improvements in the preparation of liposome-encapsulated drugs in regard to the scientific and medical stakes.