ObjectiveThe potential risk of a nanoparticle as a medical application has raised wide concerns, and this study aims to investigate silver nanoparticle (AgNP)-induced acute toxicities, genotoxicities, target organs and the underlying mechanisms.MethodsSprague-Dawley rats were randomly divided into 4 groups (n = 4 each group), and AgNP (containing Ag nanoparticles and released Ag+, 5 mg/kg), Ag+ (released from the same dose of AgNP, 0.0003 mg/kg), 5% sucrose solution (vechicle control) and cyclophophamide (positive control, 40 mg/kg) were administrated intravenously for 24 h respectively. Clinical signs and body weight of rats were recorded, and the tissues were subsequently collected for biochemical examination, Ag+ distribution detection, histopathological examination and genotoxicity assays.ResultsThe rank of Ag detected in organs from highest to lowest is lung>spleen>liver>kidney>thymus>heart. Administration of AgNP induced a marked increase of ALT, BUN, TBil and Cre. Histopathological examination results showed that AgNP induced more extensive organ damages in liver, kidneys, thymus, and spleen. Bone marrow micronucleus assay found no statistical significance among groups (p > 0.05), but the number of aberration cells and multiple aberration cells were predominately increased from rats dosed with Ag+ and AgNP (p < 0.01), and more polyploidy cells were generated in the AgNP group (4.3%) compared with control.ConclusionOur results indicated that the AgNP accumulated in the immune system organs, and mild irritation was observed in the thymus and spleen of animals treated with AgNP, but not with Ag+. The liver and kidneys could be the most affected organs by an acute i.v. dose of AgNP, and significantly increased chromosome breakage and polyploidy cell rates also implied the potential genotoxicity of AgNP. However, particle-specific toxicities and potential carcinogenic effect remain to be further confirmed in a chronic toxicity study.

The utility and sensitivity of the newly developed flow cytometric Pig‐a gene mutation assay have become a great concern recently. In this study, we have examined the feasibility of integrating the Pig‐a assay as well as micronucleus and Comet endpoints into acute and subchronic general toxicology studies. Male Sprague–Dawley rats were treated for 3 or 28 consecutive days by oral gavage with procarbazine hydrochloride (PCZ) or ethyl carbamate (EC) up to the maximum tolerated dose. The induction of CD59‐negative reticulocytes and erythrocytes, micronucleated reticulocytes in peripheral blood, micronucleated polychromatic erythrocytes in bone marrow, and Comet responses in peripheral blood, liver, kidney, and lung were evaluated at one, two, or more timepoints. Both PCZ and EC produced positive responses at most analyzed timepoints in all tissue types, both with the 3‐day and 28‐day treatment regimens. Furthermore, comparison of the magnitude of the genotoxicity responses indicated that the micronucleus and Comet endpoints generally produced greater responses with the higher dose, short‐term treatments in the 3‐day study, while the Pig‐a assay responded better to the cumulative effects of the lower dose, but repeated subchronic dosing in the 28‐day study. Collectively, these results indicate that integration of several in vivo genotoxicity endpoints into a single routine toxicology study is feasible and that the Pig‐a assay may be particularly suitable for integration into subchronic dose studies based on its ability to accumulate the mutations that result from repeated treatments. This characteristic may be especially important for assaying lower doses of relatively weak genotoxicants. Environ. Mol. Mutagen. 60:56–71, 2019. © 2018 Wiley Periodicals, Inc.

Our current knowledge on nanomaterials is mostly built on data from basic studies, and the application and developmental potentials of nanomaterials are emphasized. On the other hand, standard evaluation methods, models, exposure methods, standards, and guidelines for biological effect evaluation are inadequate. In response to the bottlenecks of supervision, scientific research institutes and regulatory organizations in China have cooperated closely to research and establish an evaluation system for nanomedical devices, and silver‐containing nanomaterials have been adopted as an example. In such a context, reference materials, characterization strategies, in vitro and in vivo distribution and toxicity evaluation standards have been established. This article highlights research on the risk assessment of nanomedical device products (taking silver‐containing nanomedical device products as an example) in China, including the characterization and release determination strategies, determination of nanosilver in tissues, applications of three‐dimensional skin models and in vitro and toxicity evaluation standards have been established. This article highlights research on technical standards. As a consequence, the “Guidelines for the safety and effectiveness evaluation of nanomedical devices” were published in 2021, and a market entry framework for nanomedical devices has been preliminarily formed as a significant component in scientific supervision. This Guideline supervises the review and supervision of nanomedical devices and, therefore, provides a guarantee for the market access of nanomedical devices in China.This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine