An improved in vitro model simulating the feto-maternal interface to study developmental effects of potentially toxic compounds: The example of titanium dioxide nanoparticles.

The study of developmental effect of xenobiotics in humans is limited and often relies on epidemiological data. Whether and to which extent potentially toxic compounds may cross the placental barrier, and whether adverse effects on embryo development are the consequence of direct or indirect placental-mediated action is debated. The availability of in vitro models simulating the feto-maternal interface could contribute to elucidate this issue. Here, we report the development of a novel in vitro model using murine blastocyst derived trophoblast stem cells (TSC) to mimic the placental barrier and mouse embryoid bodies (EBs) to represent the embryonic tissues. We demonstrate that this model can be used for translocation studies, as well as embryotoxicity assessment of titanium dioxide nanoparticles (TiO2NPs). By evaluating trans-epithelial electrical resistance, translocation of fluorescein isothiocyanate-dextran beads and expression of junctional complex proteins, we show that TSCs cultured on transwell inserts under differentiating condition form syncytia. We also show that TiO2NPs administered in the upper transwell compartment are able to reach the lower compartment and interfere with EB differentiation when no TSC are cultured on the insert. On the contrary, when TSC are present, NPs translocate to a lesser extent and do not affect EB development. These results indicate that the proposed in vitro model is suitable to study the correlation between translocation and toxicity of TiO2NPs and suggest a direct effect of the particles on EB development. We propose that this model could be exploited to study developmental effect of other xenobiotics.

Silica encapsulation of ZnO nanoparticles reduces their toxicity for cumulus cell-oocyte-complex expansion.

BACKGROUND: Metal oxide nanoparticles (NPs) are increasingly used in many industrial and biomedical applications, hence their impact on occupational and public health has become a concern. In recent years, interest on the effect that exposure to NPs may exert on human reproduction has grown, however data are still scant. In the present work, we investigated whether different metal oxide NPs interfere with mouse cumulus cell-oocyte complex (COC) expansion. METHODS: Mouse COCs from pre-ovulatory follicles were cultured in vitro in the presence of various concentrations of two types of TiO2 NPs (JRC NM-103 and NM-104) and four types of ZnO NPs (JRC NM-110, NM-111, and in-house prepared uncoated and SiO2-coated NPs) and the organization of a muco-elastic extracellular matrix by cumulus cells during the process named cumulus expansion was investigated. RESULTS: We show that COC expansion was not affected by the presence of both types of TiO2 NPs at all tested doses, while ZnO NM-110 and NM-111 induced strong toxicity and inhibited COCs expansion at relatively low concentration. Medium conditioned by these NPs showed lower toxicity, suggesting that, beside ion release, inhibition of COC expansion also depends on NPs per se. To further elucidate this, we compared COC expansion in the presence of uncoated or SiO2-coated NPs. Differently from the uncoated NPs, SiO2-coated NPs underwent slower dissolution, were not internalized by the cells, and showed an overall lower toxicity. Gene expression analysis demonstrated that ZnO NPs, but not SiO2-coated ZnO NPs, affected the expression of genes fundamental for COC expansion. Dosimetry analysis revealed that the delivered-to-cell mass fractions for both NPs was very low. CONCLUSIONS: Altogether, these results suggest that chemical composition, dissolution, and cell internalization are all responsible for the adverse effects of the tested NPs and support the importance of a tailored, safer-by-design production of NPs to reduce toxicity.

Skin sensitization among night shift and daytime healthcare workers: a cross sectional study.

OBJECTIVE: Allergic contact dermatitis (ACD) in the healthcare sector is a major occupational health hazard. There are many reasons for a higher frequency of ACD in healthcare personnel compared to other populations: among others, simultaneous exposure to multiple substances, use of aggressive detergents and wet work. However, studies that systematically correlate skin symptoms with the presence of sensitization investigated through patch tests in specific categories of health workers are very rare and conflicting. Although some studies have reported a correlation between skin disease and night shift, the strength of the evidence is rather limited. The purpose of our study was to investigate by means of patch testing the skin sensitization (SS) to common allergens in the hospital setting in a group of healthcare workers (HCW) reporting symptoms related to dermatitis, according to their job activity and their shift status. METHODS: 132 HCWs visiting a health surveillance centre were investigated by means of specific questionnaire for dermatitis, followed by patch test evaluation including 40 haptens of the SIDAPA 2016 series. RESULTS: Skin sensitization was observed in 1/3 of the subjects investigated by patch tests. The nursing job was strongly associated with cutaneous reactivity after controlling for the confounding of gender, age and other factors. Shift work was related to the prevalence of SS. CONCLUSIONS: In our study, the nurse's role and shift work were significantly associated with the risk of cutaneous sensitization, in particular for common antigens.

Relationship between the night shift work and thyroid disorders: A systematic review and meta-analysis.

OBJECTIVES: The night shift workers were reported to have health consequences, ranging from mild, as cluster headache, to severe, as heart attacks and hormonal irregularities. This study is aimed to perform a systematic review and meta-analyze of the association between the night shift work and the thyroid disorders. METHODS: We comprehensively searched eight databases, including PubMed and Google Scholar for the relevant articles. This systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. RESULTS: We finally included six papers involving 4074 participants. Four papers were eligible for meta-analysis involving 1864 night shift workers and 2017 day shift workers. We against found that thyroid stimulating hormone (TSH) is significantly higher in the night shift group compared to the day shift group. CONCLUSIONS: The higher TSH among the night shift workers is attributed to disruption of the circadian rhythm and sleep/wake cycle, with subsequent eating disorders. We proposed that more attention should be paid to the working pattern and the related health consequences.

A Body Tracking-Based Low-Cost Solution for Monitoring Workers' Hygiene Best Practices during Pandemics.

Since its beginning at the end of 2019, the pandemic spread of the severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) caused more than one million deaths in only nine months. The threat of emerging and re-emerging infectious diseases exists as an imminent threat to human health. It is essential to implement adequate hygiene best practices to break the contagion chain and enhance society preparedness for such critical scenarios and understand the relevance of each disease transmission route. As the unconscious hand-face contact gesture constitutes a potential pathway of contagion, in this paper, the authors present a prototype system based on low-cost depth sensors able to monitor in real-time the attitude towards such a habit. The system records people's behavior to enhance their awareness by providing real-time warnings, providing for statistical reports for designing proper hygiene solutions, and better understanding the role of such route of contagion. A preliminary validation study measured an overall accuracy of 91%. A Cohen's Kappa equal to 0.876 supports rejecting the hypothesis that such accuracy is accidental. Low-cost body tracking technologies can effectively support monitoring compliance with hygiene best practices and training people in real-time. By collecting data and analyzing them with respect to people categories and contagion statistics, it could be possible to understand the importance of this contagion pathway and identify for which people category such a behavioral attitude constitutes a significant risk.

Severe facial reaction to thiurams in surgeons

Contact dermatitis is a major problem in the healthcare environment and in other sectors. Healthcare professionals may be exposed to a large number of chemical agents, including the accelerators for rubber vulcanization process. The prevalence of allergic contact dermatitis among operators in the sector ranges 13­30%. This paper describes the case of a 46-year-old male cardiac surgeon affected by a severe skin reaction localized on the face in the absence of hand dermatitis, presumably resulting from the use of a surgical patch applied to the face. Patch tests were performed and the result was negative for latex and positive (+++) for thiuram mix. A thiuram-free tape was prescribed and the operator's dermatitis improved significantly. Thus, it would be very important to pay attention to skin disorders in health workers and thiuram as an occupational allergen. Med Pr. 2019;70(1):121­4

Relevance to investigate different stages of pregnancy to highlight toxic effects of nanoparticles: The example of silica.

Amorphous silica nanoparticles (SiO2NPs) have been recognized as safe nanomaterial, hence their use in biomedical applications has been explored. Data, however, suggest potential toxicity of SiO2 NPs in pregnant individuals. However, no studies relating nanoparticle biokinetic/toxicity to the different gestational stages are currently available. In this respect, we have investigated the possible embryotoxic effects of three-size and two-surface functionalization SiO2NPs in mice. After intravenous administration of different concentrations at different stages of pregnancy, clinical and histopathological evaluations, performed close to parturition, did not show signs of maternal toxicity, nor effects on placental/fetal development, except for amino-functionalized 25 nm NPs. Biodistribution was studied by ICP-AES 24 h after administration, and demonstrates that all particles distributed to placenta and conceptuses/fetuses, although size, surface charge and gestational stage influenced biodistribution. Our data suggest the need of comprehensive toxicological studies, covering the entire gestation to reliably assess the safety of nanoparticle exposure during pregnancy.

The unrecognized occupational relevance of the interaction between engineered nanomaterials and the gastro-intestinal tract: a consensus paper from a multidisciplinary working group.

BACKGROUND: There is a fundamental gap of knowledge on the health effects caused by the interaction of engineered nanomaterials (ENM) with the gastro-intestinal tract (GIT). This is partly due to the incomplete knowledge of the complex physical and chemical transformations that ENM undergo in the GIT, and partly to the widespread belief that GIT health effects of ENM are much less relevant than pulmonary effects. However, recent experimental findings, considering the role of new players in gut physiology (e.g. the microbiota), shed light on several outcomes of the interaction ENM/GIT. Along with this new information, there is growing direct and indirect evidence that not only ingested ENM, but also inhaled ENM may impact on the GIT. This fact, which may have relevant implications in occupational setting, has never been taken into consideration. This review paper summarizes the opinions and findings of a multidisciplinary team of experts, focusing on two main aspects of the issue: 1) ENM interactions within the GIT and their possible consequences, and 2) relevance of gastro-intestinal effects of inhaled ENMs. Under point 1, we analyzed how luminal gut-constituents, including mucus, may influence the adherence of ENM to cell surfaces in a size-dependent manner, and how intestinal permeability may be affected by different physico-chemical characteristics of ENM. Cytotoxic, oxidative, genotoxic and inflammatory effects on different GIT cells, as well as effects on microbiota, are also discussed. Concerning point 2, recent studies highlight the relevance of gastro-intestinal handling of inhaled ENM, showing significant excretion with feces of inhaled ENM and supporting the hypothesis that GIT should be considered an important target of extrapulmonary effects of inhaled ENM. CONCLUSIONS: In spite of recent insights on the relevance of the GIT as a target for toxic effects of nanoparticles, there is still a major gap in knowledge regarding the impact of the direct versus indirect oral exposure. This fact probably applies also to larger particles and dictates careful consideration in workers, who carry the highest risk of exposure to particulate matter.

Thoracic dust exposure is associated with lung function decline in cement production workers.

We hypothesised that exposure to workplace aerosols may lead to lung function impairment among cement production workers.Our study included 4966 workers in 24 cement production plants. Based on 6111 thoracic aerosol samples and information from questionnaires we estimated arithmetic mean exposure levels by plant and job type. Dynamic lung volumes were assessed by repeated spirometry testing during a mean follow-up time of 3.5 years (range 0.7-4.6 years). The outcomes considered were yearly change of dynamic lung volumes divided by the standing height squared or percentage of predicted values. Statistical modelling was performed using mixed model regression. Individual exposure was classified into quintile levels limited at 0.09, 0.89, 1.56, 2.25, 3.36, and 14.6 mg·m(-3), using the lowest quintile as the reference. Employees that worked in administration were included as a second comparison group.Exposure was associated with a reduction in forced expiratory volume in 1 s (FEV1), forced expiratory volume in 6 s and forced vital capacity. For FEV1 % predicted a yearly excess decline of 0.84 percentage points was found in the highest exposure quintile compared with the lowest.Exposure at the higher levels found in this study may lead to a decline in dynamic lung volumes. Exposure reduction is therefore warranted.

Nanotoxicology ten years later: Lights and shadows.

The mounting societal concerns about possible and maybe even likely adverse effects of nanomaterials are reflected in a large and growing number of publications in the field of nanotoxicology. Indeed, today's search in PubMed reveals >3700 publications on the subject denoted by (toxic+nanomaterials) - quite a growth over the last decade that began with only two dozens of them up-to 2005.

New frontiers in nanotoxicology: Gut microbiota/microbiome-mediated effects of engineered nanomaterials.

It has been recently recognized that the gut microbiota, the community of organisms living within the gastrointestinal tract is an integral part of the human body, and that its genoma (the microbiome) interacts with the genes expressed by the cells of the host organism. Several important physiological functions require the cooperation of microbiota/microbiome, whose alterations play an important role in several human diseases. On this basis, it is probable that microbiota/microbiome may in part be involved in many biological effects of engineered nanomaterials (ENMs). There are still few reports on the possible toxicological effects of ENMs on microbiota/microbiome, and on their possible clinical consequences. Available data suggest that several ENMs, including carbon nanotubes (CNTs), titanium dioxide, cerium dioxide, zinc oxide, nanosilica and nanosilver may affect the microbiota and that clinical disorders such as colitis, obesity and immunological dysfunctions might follow. On the other hand, other ENMs such as iron nanoparticles may show advantages over traditional iron-based supplemental treatment because they do not interfere with the microbiota/microbiome, and some ENM-based therapeutic interventions might be employed for treating intestinal infections, while sparing the microbiota. The final section of the review is focused on the possible future developments of the research in this field: new in vitro and in vivo models, possible biomarkers and new pathophysiological pathways are proposed and discussed, as well as the possibility that metabolic changes following ENMs/microbiota interactions might be exploited as a fingerprint of ENM exposure. The potential toxicological relevance of physico-chemical modifications of ENMs induced by the microbiota is also highlighted.

Multi-walled carbon nanotubes directly induce epithelial-mesenchymal transition in human bronchial epithelial cells via the TGF-ß-mediated Akt/GSK-3ß/SNAIL-1 signalling pathway.

BACKGROUND: Multi-walled carbon nanotubes (MWCNT) are currently under intense toxicological investigation due to concern on their potential health effects. Current in vitro and in vivo data indicate that MWCNT exposure is strongly associated with lung toxicity (inflammation, fibrosis, granuloma, cancer and airway injury) and their effects might be comparable to asbestos-induced carcinogenesis. Although fibrosis is a multi-origin disease, epithelial-mesenchymal transition (EMT) is recently recognized as an important pathway in cell transformation. It is known that MWCNT exposure induces EMT through the activation of the TGF-ß/Smad signalling pathway thus promoting pulmonary fibrosis, but the molecular mechanisms involved are not fully understood. In the present work we propose a new mechanism involving a TGF-ß-mediated signalling pathway. METHODS: Human bronchial epithelial cells were incubated with two different MWCNT samples at various concentrations for up to 96 h and several markers of EMT were investigated. Quantitative real time PCR, western blot, immunofluorescent staining and gelatin zymographies were performed to detect the marker protein alterations. ELISA was performed to evaluate TGF-ß production. Experiments with neutralizing anti-TGF-ß antibody, specific inhibitors of GSK-3ß and Akt and siRNA were carried out in order to confirm their involvement in MWCNT-induced EMT. In vivo experiments of pharyngeal aspiration in C57BL/6 mice were also performed. Data were analyzed by a one-way ANOVA with Tukey's post-hoc test. RESULTS: Fully characterized MWCNT (mean length < 5 µm) are able to induce EMT in an in vitro human model (BEAS-2B cells) after long-term incubation at sub-cytotoxic concentrations. MWCNT stimulate TGF-ß secretion, Akt activation and GSK-3ß inhibition, which induces nuclear accumulation of SNAIL-1 and its transcriptional activity, thus contributing to switch on the EMT program. Moreover, a significant increment of nuclear ß-catenin - due to E-cadherin repression and following translocation to nucleus - likely reinforces signalling for EMT promotion. In vivo results supported the occurrence of pulmonary fibrosis following MWCNT exposure. CONCLUSIONS: We demonstrate a new molecular mechanism of MWCNT-mediated EMT, which is Smad-independent and involves TGF-ß and its intracellular effectors Akt/GSK-3ß that activate the SNAIL-1 signalling pathway. This finding suggests potential novel targets in the development of therapeutic and preventive approaches.

[Risk of tuberculosis in healthcare workers: risk assessment and medical surveillance]. / Rischio tubercolosi in ambiente sanitario. Valutazione del rischio e sorveglianza sanitaria.

Tuberculosis screening is recommended for all health care workers. We evaluated the prevalence of latent tuberculosis infection among 939 hospital workers of Tor Vergata University teaching hospital in Rome, Italy, in the period 2007-2013, by using the QuantiFERON Gold In-Tube (QFT) test. The mean age of subjects tested was 31 years. The prevalence of positive subjects (cut-off 0.35 UI/ml) was 5.5% (46/939) and the mean age of those who tested positive was 39 years. The low rate of positivity may be partly related to the higher reliability of QFT in comparison to tuberculin skin testing.

[Ultrafine particle emissions from laser printers]. / Particelle ultrafini emesse da stampanti laser.

In recent years there has been growing attention to the importance of indoor air quality on which scientist and experts have no doubts since in modern society we tend to spend most of the time in various types of indoor environments (office, private homes, etc.). Laser printers, in particular, release an aerosol into the environment including solid and liquid particles and gaseous compounds. The measurement of all these components is not practically feasible. Therefore, it is necessary to identify a marker which, when measured, shows accurately the frequency, duration and magnitude of the exposure. The measure with an optical particle counter (OPC) and a condensation particle counter (CPC) is an indicator with high sensitivity and representativeness. The major advantage of using these tools is the ability to detect the presence of ultrafine particles and also detect the particles in the liquid phase. The continuous recording of submicron particulate matter emitted during the printing activity allows to measure the exposure of personnel, while the ratio between the peak values and the values without printing activity can be used to classify the printers according to their emissivity. The particulate generated during the processes of printing has size less than 0.3 micron and therefore extends in the size range of nanoparticles (ultrafine particles less than 100 nm). These activities lead to high concentrations of ultrafine particles with a variability related to factors such as type of printer, toner, paper type, frequency of maintenance and air exchange. The concentrations of ultrafine particles in office environments can be reduced by proper choice of the printers, with the use of appropriate filtration techniques and placing the equipment away from workstations.

[In-depth assessment of work-related stress in a major company undergoing restructuring]. / La valvutazione approfondita dello stress lavoro correlate in una grande azienda in cambiamento.

BACKGROUND: An in-depth assessment of work-related stress was conducted in a major national telecommunications company undergoing major changes. The assessment was made on three homogeneous groups of workers and covered a large representative sample of the corresponding populations. OBJECTIVES: To identify the main sources of stress for the three populations of workers, stimulate a discussion on the possible corrective actions, and assess the impact of the on-going organizational changes on workers' health. METHODS: The assessment started with an analysis of the objective stress indicators listed in the INAIL (National Insurance Institute for Occupational Diseases and Accidents) Checklist. This was followed by a combination of qualitative and quantitative investigations on work context and tasks and on the subjective perceptions of workers, which were carried out by using: semi-structured interviews with management, field observations of work tasks, focus groups and questionnaires (GHQ-12, HSE Indicator Tool, ad-hoc questionnaire). RESULTS: The assessment allowed identification of the critical areas to be addressed with specific interventions: relationship with the company, work performance, work organization, and equipment. CONCLUSIONS: the investigation allowed to identification of specific practical actions (improvement of technological tools; professional development through training courses) as well as strategic actions ( re-establish relationship of trust with the company) so as to mitigate the workers' level of stress. Analysis of the results also showed that the three targeted populations differed in the degree of acceptance and understanding of the organizational changes.

Chronic obstructive pulmonary disease (COPD) patients with osteoporotic vertebral compression fractures (OVCFs): improvement of pulmonary function after percutaneous vertebroplasty (VTP).

OBJECTIVES: To investigate the changes of respiratory function in patients affected by chronic obstructive pulmonary disease (COPD) with single dorsal osteoporotic vertebral compression fractures (OVCFs) treated with vertebroplasty (VTP). METHODS: Forty-five patients affected by COPD and single dorsal OVCF underwent VTP (29 men, 16 women; mean age 71.4 years, range 65-77 years). Inclusion criteria were magnetic resonance findings of bone marrow oedema, without intracanal bone fragments and refractory pain to medical treatment for at least 3 months. Osteoporosis was assessed by bone densitometry. Spirometry was performed before and after treatment. RESULTS: A significant VAS-score decrease was observed 1 week after VTP, with a subsequent decrease over time; vital capacity (VC) and forced vital capacity (FVC) improved over time, reaching a plateau at 3 months. Forced expiratory volume at 1 s (FEV1) did not significantly differ between the pre-VTP values and follow-up values. A significant correlation was observed between VAS-score values and VC, and VAS-score values and FVC. No significant correlation was observed between VAS-score values and FEV1 values. CONCLUSIONS: VTP improves restrictive ventilatory impairment in patients with moderate and severe COPD affected by single thoracic OVCFs. We recommend this treatment in the management of these patients. KEY POINTS: • Osteoporosis is a major comorbidity in chronic obstructive pulmonary disease (COPD) patients. • Pain due to osteoporotic vertebral compression fractures worsens respiratory failure in COPD. • Vertebroplasty improves ventilatory impairment in COPD patients with osteoporotic vertebral compression fractures.

Targeted nanodrugs for cancer therapy: prospects and challenges.

The recent advent of nanomedicine holds potential to revolutionize cancer therapy. This innovative discipline has paved the way for the emergence of a new class of drugs based on nanoengineered particles. These "nanodrugs" are designed to greatly enhance drug therapeutic indices. First-generation nanodrugs consisted of conventional anti-cancer drugs loaded into/onto nanoengineered particles (nanocarriers) devoid of targeting features (non-targeted nanodrugs). Non-targeted nanodrugs have provided the opportunity to carry large amounts of drugs, including poorly water-soluble and/or permeable drugs, to several types of tumors, improving the therapeutic index with respect to comparable free drugs. Although effective, the primary delivery mechanism of non-targeted nanodrugs was through passive tissue accumulation, due to pathophysiological differences between tumor-associated and healthy vessels, and through non-specific targeting of cell subsets, posing the danger of off-target binding and effects. Recently, the therapeutic indices of certain anti-cancer drugs were further improved by attaching targeting ligands to nanodrugs (targeted-nanodrugs). Targeted-nanodrugs selectively bind to cognate receptors expressed on target cells and enter cells more efficiently than non-targeted formulations. Although these advancements have been sufficiently beneficial to place targeted-nanodrugs into clinical development for use in cancer therapy, they also come at a price. The addition of ligands to drug-loaded nanocarriers often leads to additional synthesis steps and costs, and more complex biological performance relative to ligand-devoid nanodrugs. Here, we will discuss the benefits and challenges facing the addition of targeting features to nanodrugs for cancer therapy.

Maternal exposure to zinc oxide nanoparticles causes cochlear dysfunction in the offspring.

Introduction: Zinc oxide nanoparticles (ZnO NPs) have been engineered and are largely used in material science and industry. This large and increasing use justifies a careful study about the toxicity of this material for human subjects. The concerns regard also the reproductive toxicity and the fetotoxicity. Materials and methods: The effect of the exposure to ZnO NPs on the cochlear function was studied in a group of pregnant CD1 mice and in their offspring. This study is part of a larger toxicological study about the toxicity of ZnO NPs during pregnancy. Four groups were analyzed and compared, exposed and non-exposed dams and their offspring. The cochlear function was quantitatively assessed by means of Distortion Product Otoacoustic Emissions (DPOAEs). Results and discussion: A large statistically significant difference was found between the non-exposed dams offspring and the exposed dams offspring (p = 1.6 · 10-3), whose DPOAE levels were significantly lower than those of non-exposed dams offspring and comparable to those of the adults. The DPOAE levels of the exposed and non-exposed dams were very low and not significantly different. This occurrence is related to the fact that these mice encounter a rapid aging process. Conclusion: Our findings show that maternal exposure to ZnO NPs does not reflect in overt toxicity on fetal development nor impair offspring birth, however it may damage the nervous tissue of the inner ear in the offspring. Other studies should confirm this result and identify the mechanisms through which ZnO NPs may affect ear development.

Interactions of engineered nanoparticles with organs protected by internal biological barriers.

Engineered nanomaterials may exert adverse effects on human health which, in turn, may be linked to their propensity to cross biological barriers in the body. Here, available evidence is discussed, based on in vivo studies for interactions of commercially relevant nanoparticles with critical internal barriers. The internal barriers in focus in this review are the blood-brain barrier, protecting the brain, the blood-testis barrier, protecting the male germ line, and the placenta, protecting the developing fetus. The route of exposure (pulmonary, gastro-intestinal, intravenous, intraperitoneal, dermal), and, hence, the portal of entry of nanoparticles into the body, is of critical importance. Different physico-chemical properties, not only size, may determine the ability of nanoparticles to breach biological barriers; the situation is further compounded by the formation of a so-called corona of biomolecules on the surfaces of nanoparticles, the composition of which may vary depending on the route of exposure and the translocation of nanoparticles from one biological compartment to another. The relevance of nanoparticle interactions with internal biological barriers for their impact on the organs protected by these barriers is also discussed.

Biodistribution and toxicity of pegylated single wall carbon nanotubes in pregnant mice.

BACKGROUND: Single wall carbon nanotubes (SWCNTs) are considered promising nanoparticles for industrial and biomedical applications; however their potential toxicity in several biological systems, including the feto-placental unit, has been demonstrated. Functionalization of SWCNTs with polyethylene glycol chains (PEG-SWCNTs) dramatically reduces their toxicity, and for this reason PEG-SWCNTs are candidates for biomedical applications. However, no data are available on their safety for the developing embryo, in spite of the clinical and social relevance of this topic. The purpose of this study is therefore to investigate the safety of PEG-SWCNTs for their use as biomedical carriers in pregnancy. METHODS: For toxicological studies, amino-functionalized PEG-SWCNT were intravenously injected in CD1 pregnant mice at different doses (range 0.1-30 µg/mouse), in single or multiple administrations. For biodistribution studies, fluorescently labeled PEG-SWCNTs were obtained by acylation of terminal PEG amino groups with near infrared emitting fluorochromes (PEG-SWCNT-750) and injected at the dosage of 10 µg/mouse, at either day 5.5 (when the placenta is still developing) or day 14.5 of gestation (when the maturation of the placenta is complete). RESULTS: We found no adverse effects both on embryos and dams up to the dose of 10 µg/mouse. At the dose of 30 µg/mouse, occasional teratogenic effects, associated with placental damage, were detected both when administered as a single bolus (1 out of 10 dams; 1 malformed embryo) or as multiple doses (2 out of 10 dams; 5 malformed embryos). The difference in the prevalence of dams with malformed embryos between the 30 µg exposed group and controls approached the statistical significance (p = 0.06). Hepatic damage in dams was seen only in the multiple exposure group (4 out of 10; p = 0.04 when compared with the single exposure group or controls). PEG-SWCNT-750 reached the conceptus when administered early in pregnancy. At later stages, PEG-SWCNT-750 were detected in the placenta and the yolk sac, but not in the embryo. CONCLUSIONS: PEG-SWCNTs may cause occasional teratogenic effects in mice beyond a threshold dose. Such effect might depend on their ability to reach the feto-placenta unit. Although not automatically transferable to humans, these data should be considered if exposing women during pregnancy.