Significant Genotoxicity Research Articles

RETRACTED: Genotoxicity assessment of cerium oxide nanoparticles in female Wistar rats after acute oral exposure

Cerium oxide nanoparticles (CeO2 NPs; nanoceria) have demonstrated excellent potential for commercial use in various arenas, such as in biomedical industry in cosmetics and as a fuel additive. However, limited knowledge exists regarding their potential toxicity. In this study, acute oral toxicity of CeO2 NPs and their microparticles (MPs; bulk) was carried out in female albino Wistar rats. The CeO2 NPs and CeO2 MPs were characterized utilizing transmission electron microscopy (TEM), dynamic light scattering (DLS) and laser Doppler velocimetry (LDV) for the size, distribution and surface charge respectively. The genotoxicity studies were conducted using micronucleus test (MNT), comet and chromosomal aberration (CA) assays. Results revealed that at high dose (1000mg/kg bw) CeO2 NPs induced significant DNA damage in peripheral blood leukocytes (PBL) and liver cells, micronucleus formation in bone marrow and blood cells and total cytogenetic changes in bone marrow. However, significant genotoxicity was not observed at 500 and 100mg/kg bw of CeO2 NPs. The findings from biochemical assays depicted significant alterations in ALP and LDH activity in serum and GSH content in liver, kidneys and brain only at the high dose of CeO2 NPs. Tissue biodistribution of both particles was analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES). Bioaccumulation of nanoceria in all tissues was significant and dose-, time- and organ-dependent. Moreover, CeO2 NPs exhibited higher tissue distribution along with greater clearance in large fractions through urine and feces than CeO2 bulk, whereas, maximum amount of micro-sized CeO2 got excreted in feces. The histopathological examination documented alterations in the liver due to exposure with CeO2 NPs only. Hence, the results suggest that bioaccumulation of CeO2 NPs may induce genotoxic effects. However, further research on long term fate and adverse effects of CeO2 NPs is warranted.

Characterization of a Melamino Nitroheterocycle as a Potential Lead for the Treatment of Human African Trypanosomiasis

This paper reports an evaluation of a melamino nitroheterocycle, a potential lead for further development as an agent against human African trypanosomiasis (HAT). Studies on its efficacy, physicochemical and biopharmaceutical properties, and potential for toxicity are described. The compound previously had been shown to possess exceptional activity against Trypanosoma brucei in in vitro assays comparable to that of melarsoprol. Here, we demonstrate that the compound also was curative in the stringent acute mouse model T. brucei rhodesiense STIB 900 when given intraperitoneally at 40 mg/kg of body weight. Nevertheless, activity was only moderate when the oral route was used, and no cure was obtained when the compound was tested in a stage 2 rodent model of infection. Genotoxic profiling revealed that the compound induces DNA damage by a mechanism apparently independent from nitroreduction and involving the introduction of base pair substitutions (Ames test), possibly caused by oxidative damage of the DNA (comet test). No significant genotoxicity was observed at the chromosome level (micronucleus assay). The lack of suitable properties for oral and central nervous system uptake and the genotoxic liabilities prevent the progression of this melamine nitroheterocycle as a drug candidate for HAT. Further modification of the compound is required to improve the pharmacokinetic properties of the molecule and to separate the trypanocidal activity from the toxic potential.

Hancornia speciosa latex for biomedical applications: physical and chemical properties, biocompatibility assessment and angiogenic activity.

The latex obtained from Hancornia speciosa is used in folk medicine for treatment of several diseases, such as acne, warts, diabetes, gastritis and inflammation. In this work, we describe the biocompatibility assessment and angiogenic properties of H. speciosa latex and its potential application in medicine. The physical-chemical characterization was carried out following different methodologies (CHN elemental analyses; thermogravimetric analyses and Fourier transform infrared spectroscopy). The biocompatibility was evaluated through cytotoxicity and genotoxicity tests in fibroblast mouse cells and the angiogenic properties were evaluated using the chick chorioallantoic membrane (CAM) assay model. The physical-chemical results showed that the structure of Hancornia speciosa latex biomembrane is very similar to that of Hevea brasiliensis (commercially available product). Moreover, the cytotoxicity and genotoxicity assays showed that H. speciosa latex is biocompatible with life systems and can be a good biomaterial for medical applications. The CAM test showed the efficient ability of H. speciosa latex in neovascularization of tissues. The histological analysis was in accordance with the results obtained in the CAM assay. Our data indicate that the latex obtained from H. speciosa and eluted in water showed significant angiogenic activity without any cytotoxic or genotoxic effects on life systems. The same did not occur with H. speciosa latex stabilized with ammonia. Addition of ammonia does not have significant effects on the structure of biomembranes, but showed a smaller cell survival and a significant genotoxicity effect. This study contributes to the understanding of the potentialities of H. speciosa latex as a source of new phytomedicines.

Sodium arsenite induced changes in survival, growth, metamorphosis and genotoxicity in the Indian cricket frog (Rana limnocharis)

Arsenic contamination of the environment is a matter of great concern. Understanding the effects of arsenic on aquatic life will act as biological early warning system to assess how arsenic could shape the biodiversity in the affected areas. Rapid decline in amphibian population in recent decades is a cause of major concern. Over the years, amphibians have been recognized as excellent bio-indicators of environmental related stress. In the present study, we examined the toxic and genotoxic effects of sodium arsenite in the tadpoles of the Indian cricket frog (Rana limnocharis). Sodium arsenite at different concentrations (0, 50, 100, 200 and 400μgL−1) neither induced lethality nor significantly altered body weight at metamorphosis. However, it accelerated the rate of metamorphosis at higher concentrations, reduced body size (snout–vent length) and induced developmental deformities such as loss of limbs. Besides, at concentration ranges between 100 and 400μgL−1, sodium arsenite induced statistically significant genotoxicity at 24, 48, 72 and 96h of the exposure in a concentration-dependent manner. However, it did not show time effects as the highest frequency was found between 48 and 72h which remained steady subsequently. The genotoxicity was confirmed by comet assay in the whole blood cells. These findings suggest that arsenic at environmentally relevant concentrations has significant sub-lethal effects on R.limnocharis, which may have long-term fitness consequence to the species and may have similar implications in other aquatic life too.

Reduction of acute toxicity and genotoxicity of dye effluent using Fenton-coagulation process

Dye wastewater exhibits significant ecotoxicity even though its physico-chemical parameters meet the discharge standards. In this work, the acute toxicity and genotoxicity of dye effluent were tested, and the Fenton-coagulation process was carried out to detoxify this dye effluent. The acute toxicity was evaluated according to the mortality rate of zebrafish, and genotoxicity was evaluated by micronucleus (MN) and comet assays. Removal of color and chemical oxygen demand (COD) was also investigated. The results indicated that the dye effluent showed strong acute toxicity and genotoxicity to zebrafish. After 4h of treatment by Fenton-coagulation process, the dye effluent exhibited no significant acute toxicity and genotoxicity to zebrafish. In addition, its COD was less than 50mg/L, which met the discharge standard. It demonstrates that Fenton-coagulation process can comprehensively reduce the acute toxicity and genotoxicity as well as the COD of the dye effluent.

APPLICATION OF MAGNETIC NANOPARTICLES IN DRINKING WATER PURIFICATION

Pathogenic bacteria are fetal to human health, requiring cost-effective and safe approaches to be removed from drinking water source. With poly-allylamine-hydrochloride (PAAH) stabilization, magnetic nanoparticles (MNPs) were introduced in this study to remove pathogenic bacteria by electrostatic interaction and magnet capture. High removal efficiency was achieved for four main pathogenic species, as Escherichia, Acinetobacter, Pseudomonas and Bacillus, and over 99.5% of the pathogens can be removed when the bacterial count was less than 105 CFU/mL. Related to various species, the MNPs have respective adhesion effects on bacterial cells, which are higher for Acinetobacter and Pseudomonas, due to the mechanisms of external cell structure and ion exchange capacity, but not the zeta potential of bacterial cell surface. With the practical application in real drinking water samples collected from reservoirs in Sheffield and Leeds, the results showed high bacteria removal efficiency (99.48%) and the total bacteria residual counts was as low as 78 CFU/mL, which met the drinking water standard of WHO (<100 CFU/mL). Further toxicity test indicated that no significant genotoxicity or cytoxicity existed in MNPs treated water, suggesting MNPs are biocompatible for safety issues in drinking water. As an effective, easy-operation and low cost technique, MNPs have bright future and great potential in practical drinking water treatment to remove pathogenic bacteria.

Cyto-genotoxicity Assessment of Potential Anti-tubercular Drug Candidate Molecule-trans-cyclohexane-1, 4-diamine Derivative-9u in Human Lung Epithelial Cells A549.

Increasing incidences of multiple drug-resistance (MDR) in Mycobacterium tuberculosis are emerging as one among the serious public health threats and socio-economic burden to the third world countries including India. Last couples of decades are witnesses of the dedicated and sustained efforts made toward the development of target specific and cost-effective antimicrobial agents against MDR-M. tuberculosis. However, the drugs in use are still incapable of controlling the upsurge of MDR. Thus, in order to address the issue, we synthesized a library of symmetrical trans-cyclohexane-1, 4-diamine derivatives and evaluated their anti-mycobacterium activity in H37RV strain of M. tuberculosis. A range of efficacy has been recorded in different derivatives of synthesized compounds and compound “9u” having i-propyl group substitution at p-position, was found to have more significant detrimental effects against the tested strain of M. tuberculosis. The present investigations were aimed to study whether the effective anti-mycobacterium concentrations of “9u” are biologically safe to human cells or not? The human lung epithelial cell line-A549 were exposed to a range of concentrations, i.e., at and above the anti-mycobacterium effective dose of “9u” for a period of 0-96 h. The standard endpoints of cytotoxicity viz., tetrazolium bromide salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide), neutral red uptake, lactate dehydrogenase release, trypan blue dye exclusion assays; and genotoxicity viz., micronucleus and chromosomal aberrations assays were used to evaluate the bio-safety of test compound. The compound “9u” shows no significant cytotoxicity and genotoxicity in A549 cells exposed to 10-5 M for 72 h, a concentration substantially higher than the concentration kill the H37Rv strain of M. tuberculosis. The compound 9u was found to be safe up to 10-4 M if given for 24 h. The data reveal the therapeutic potential of compound 9u against M. tuberculosis without any having any cytotoxicity and genotoxicity responses.

Cytotoxicity and genotoxicity of phenazine in two human cell lines

Phenazine was recently identified as a drinking water disinfection byproduct (DBP), but little is known of its toxic effects. We examined in vitro cytotoxicity and genotoxicity of phenazine (1.9–123μM) in HepG2 and T24 cell lines. Cytotoxicity was determined by an impedance-based real-time cell analysis instrument. The BrdU (5-bromo-2′-deoxyuridine) proliferation and MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) viability assays were used to examine mechanisms of cytotoxicity. Genotoxicity was determined using the alkaline comet assay. Concentration-dependent cytotoxicity was observed in HepG2 cells, primarily due to an antiproliferative effect (BrdU 24h IC50: 11μM; 48h IC50: 7.8μM) observed as low as 1.9μM. T24 cells experienced a minor antiproliferative effect (BrdU 24h IC50: 47μM; 48h IC50: 17μM). IC50 values for HepG2 proliferation and viability were 54–77% lower compared to T24 cells. In both cell lines, IC50 values for proliferation were 66–90% lower than those for viability. At phenazine concentrations producing equivalent cytotoxicity, HepG2 cells (1.9–30.8μM) experienced no significant genotoxic effects, while T24 cells (7.7–123μM) experienced significant genotoxicity at ⩾61.5μM. While these effects were seen at phenazine concentrations above those found in disinfected water, the persistence of the antiproliferative effect and the differential toxicity in each cell line deserves further study.

Using the Comet Assay to Assess the Combined and Separate Genotoxic Effects of Cd and Zn in Eisenia andrei (Oligochaeta) at Different Temperatures

Using the comet assay, the genotoxicity of Cd, Zn and Cd/Zn mixtures in Eisenia andrei was assessed after 4 weeks of exposure at 15, 20 and 25 °C. Relative to the controls, significant increases in TDNA% were observed in exposures to Cd alone at 500 and 1,000 mg/kg soil at both 20 and 25 °C, while a general decrease occurred at 15 °C. For Zn alone, a decreasing trend in TDNA% occurred at all three temperatures with increasing Zn concentration. For the Cd/Zn mixtures at 15 °C, genotoxicity was reduced at all mixture concentrations relative to the control. At 20 °C, the genotoxic response was similar to the control at all exposures. At 25 °C, the response was elevated at the 50 + 50 and 250 + 250 mg/kg mixture concentrations. In the remaining treatments at 25 °C, TDNA% was similar to the values in the respective control. The lack of consistently significant mixture genotoxicity may indicate antagonistic interactions between Cd and Zn in the mixtures. However, this was not conclusively determined because temperature alone had an inconsistent effect upon TDNA% readings in the control exposures.

Mutagenicity and recombinagenicity of Ocotea acutifolia (Lauraceae) aporphinoid alkaloids

The somatic mutation and recombination test (SMART) in wing cells of Drosophila melanogaster was used to test the mutagenic and recombinogenic activities of five aporphinoid alkaloids isolated from Ocotea acutifolia: thalicminine (1), (+)-dicentrine (2), (+)-ocoteine (3), (+)-6S-ocoteine N-oxide (4), and (+)-leucoxine (5). Third-stage larvae derived from the standard cross with wing cell markers mwh and/or flr3 were treated chronically. The frequencies of mutant spots observed in marked heterozygous descendants revealed significant dose-dependent genotoxicity for alkaloids 1–4; compounds 1 and 2 were the most active. Alkaloids 1–4 also induced mitotic recombination. The presence of a methoxyl group at C-3 (as in compound 3) lowers its genotoxic effect relative to that of unsubstituted analogue 2, and the introduction of an N-oxide functionality (3 vs. 4) further reduces genotoxicity. The very planar conformation of oxo-aporphine alkaloid 1 may account for its higher genotoxicity vs. its less-planar analogues 3 and 4. As previously reported for (+)-dicentrine (2), alkaloids 1, 3, and 4 may also be DNA intercalating agents, interfering with the catalytic activity of topoisomerases.

Zinc-finger-nucleases mediate specific and efficient excision of HIV-1 proviral DNA from infected and latently infected human T cells.

HIV-infected individuals currently cannot be completely cured because existing antiviral therapy regimens do not address HIV provirus DNA, flanked by long terminal repeats (LTRs), already integrated into host genome. Here, we present a possible alternative therapeutic approach to specifically and directly mediate deletion of the integrated full-length HIV provirus from infected and latently infected human T cell genomes by using specially designed zinc-finger nucleases (ZFNs) to target a sequence within the LTR that is well conserved across all clades. We designed and screened one pair of ZFN to target the highly conserved HIV-1 5′-LTR and 3′-LTR DNA sequences, named ZFN-LTR. We found that ZFN-LTR can specifically target and cleave the full-length HIV-1 proviral DNA in several infected and latently infected cell types and also HIV-1 infected human primary cells in vitro. We observed that the frequency of excision was 45.9% in infected human cell lines after treatment with ZFN-LTR, without significant host-cell genotoxicity. Taken together, our data demonstrate that a single ZFN-LTR pair can specifically and effectively cleave integrated full-length HIV-1 proviral DNA and mediate antiretroviral activity in infected and latently infected cells, suggesting that this strategy could offer a novel approach to eradicate the HIV-1 virus from the infected host in the future.

Biosynthesis and safety evaluation of ZnO nanoparticles

The secrets gleaned from nature have led to the development of biomimetic approaches for the growth of advanced nanomaterials. Biological methods for nanoparticle synthesis using microorganisms, enzymes, and plants or plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical methods. Here, we report extracellular mycosynthesis of ZnO-NPs by Alternaria alternata (Fr.) Keissl (1912). On treating zinc sulfate solution with fungal culture filtrate, rapid reduction of ZnSO₄ was observed leading to the formation of highly stable ZnO-NPs in the solution and up-to-date literature survey showed this was the first report of biosynthesis of ZnO-NPs using this fungus. The particles thereby obtained were characterized by different analytical techniques. EDX-spectrum revealed the presence of zinc and oxygen in the nanoparticles. FTIR spectroscopy confirmed the presence of a protein shell outside the nanoparticles which in turn also support their stabilization. DLS and TEM analysis of the ZnO-NPs indicated that they ranged in size from 45 to 150 nm with average size of 75 ± 5 nm. But potential negative impacts of nanomaterials are sometimes overlooked during the discovery phase of research. Therefore, in the present study, bio-safety of mycosynthesized ZnO-NPs were evaluated by using cytotoxicity and genotoxicity assays in human lymphocyte cells, in vitro. Cytotoxicity studied as function of membrane integrity and mitochondrial dehydrogenase activity revealed significant (P < 0.05) toxicity at treatment concentration of 500 μg/ml and above. Additionally, DNA damaging potential was also studied using comet assay. The results revealed significant genotoxicity at the highest concentration (1,000 μg/ml).

Metabolic profile and genotoxicity in obese rats exposed to cigarette smoke

Experimental studies have shown that exposure to cigarette smoke has negative effects on lipid metabolism and oxidative stress status. Cigarette smoke exposure in nonpregnant and pregnant rats causes significant genotoxicity (DNA damage). However, no previous studies have directly evaluated the effects of obesity or the association between obesity and cigarette smoke exposure on genotoxicity. Therefore, the aim of the present investigation was to evaluate DNA damage levels, oxidative stress status and lipid profiles in obese Wistar rats exposed to cigarette smoke. Female rats subcutaneously (s.c.) received a monosodium glutamate solution or vehicle (control) during the neonatal period to induce obesity. The rats were randomly distributed into three experimental groups: control, obese exposed to filtered air, and obese exposed to tobacco cigarette smoke. After a 2-month exposure period, the rats were anesthetized and killed to obtain blood samples for genotoxicity, lipid profile, and oxidative stress status analyses. The obese rats exposed to tobacco cigarette smoke presented higher DNA damage, triglycerides, total cholesterol, free fatty acids, VLDL-c, HDL-c, and LDL-c levels compared to control and obese rats exposed to filtered air. Both obese groups showed reduced SOD activity. These results showed that cigarette smoke enhanced the effects of obesity. In conclusion, the association between obesity and cigarette smoke exposure exacerbated the genotoxicity, negatively impacted the biochemical profile and antioxidant defenses and caused early glucose intolerance. Thus, the changes caused by cigarette smoke exposure can trigger the earlier onset of metabolic disorders associated with obesity, such as diabetes and metabolic syndrome.

Oxidative DNA damage may not mediate Ni-induced genotoxicity in marine mussels: Assessment of genotoxic biomarkers and transcriptional responses of key stress genes

Nickel (Ni) is a known carcinogenic and mutagenic compound and an important contaminant of aquatic environments. Ni toxicity and its potential impact on aquatic organisms are, however, not well understood. This study used an integrated approach to evaluate genotoxic effects, tissue-specific accumulation and transcriptional profiles of key genes in mussels, Mytilus galloprovincialis, exposed to a range of concentrations of Ni. The genotoxic effects assessed were total and oxidative DNA damage (DNA strand breaks measured using the enzyme modified comet assay), and induction of micronuclei (MN; clastogenic and/or aneugenic effects) using haemocytes as the target cells. Six genes (pgp, mt10, mt20, sod, hsp70 and gst) were selected for transcriptional analysis in the gills based on their key role in the stress response. Following exposure to sublethal concentrations of Ni (0–3600μgL−1) for 5 days, mussel haemocytes showed significant genotoxicity at >1800μgL−1 (4-fold increase for DNA strand breaks and 3-fold increase for MN induction). There was no significant difference between buffer (control) and enzyme treatments which target oxidised DNA bases (formamidopyrimidine glycosylase or endonuclease IIII). This suggested that, in haemocytes, oxidative DNA damage is not a major mechanism for Ni-induced genotoxicity. The expression of mt20 and gst genes in gill was up-regulated at genotoxic concentrations, whilst pgp expression was markedly up-regulated, particularly at 18μgL−1 Ni (19-fold increase). Pearson's correlation analysis revealed significant associations between % tail DNA and MN induction in haemocytes (r=0.88, p<0.05), and between Ni accumulation in foot (r=0.47, p<0.05) and digestive gland (r=0.41, p<0.05) and induction of MN in the haemocytes. Our results are the first to suggest that Ni-induced genotoxicity in mussel haemocytes may not be a result of oxidative DNA damage, and that multixenobiotic resistance (MXR) may play an important role in Ni detoxification in this species.

Comparison of the in vivo and in vitro genotoxicity of glyphosate isopropylamine salt in three different organisms

There is considerable controversy with regard to the genotoxicity of glyphosate, with some reports stating that this compound is non-toxic for fish, birds and mammals. In this work, we used the comet assay to examine the genotoxicity of glyphosate isopropylamine (0.7, 7, 70 and 700 μM) in human lymphocytes, erythrocytes of Oreochromis niloticus and staminal nuclei of Tradescantia (4430) in vitro and in vivo. Cells, nuclei and fish that had and had not been exposed to 5 mM N-nitrosodiethylamine (NDEA) were used as positive and negative controls, respectively. Significant (p < 0.01) genetic damage was observed in vivo and in vitro in all cell types and organisms tested. Human lymphocytes and Tradescantia hairs showed lower genetic damage in vivo compared to in vitro, possibly because of efficient metabolization of the herbicide. In O. niloticus erythrocytes, significant (p < 0.001) genotoxicity was observed at ≥ 7 μM, whereas in vitro, glyphosphate was genotoxic in human lymphocytes and Tradescantia hairs at ≥ 0.7 μM. These results indicate that glyphosate is genotoxic in the cells and organisms studied at concentrations of 0.7-7 μM.

Assessment of genotoxicity of inorganic mercury in rats in vivo using both chromosomal aberration and comet assays

The major objective of the present investigation was to assess the genotoxic effects of mercuric chloride (HgCl2), an inorganic mercury (Hg), in rats (Rattus norvegicus) using two different genetic endpoints, namely, chromosomal aberration (CA) and comet assays following both short-term (acute) and long-term (chronic) exposures. The study showed that the acute exposures to HgCl2 at 2 and 5 mg/kg body weight (b.w.) induced nonsignificant effects. HgCl2 at 10 and 12 mg/kg b.w. was significantly toxic and is exhibited by the induction of different types of CAs like chromatid breaks, chromosomal breaks, clumps and damaged cells and types of comets. HgCl2 at 15 mg/kg b.w. was found to be highly toxic, as mitostatic condition of cells were observed in CA assay. Chronic exposure to the lowest dose (2 mg/kg b.w.) of HgCl2 for 15 consecutive days produced a significant genotoxicity. Although Hg was found to induce both DNA strand breakage and chromosomal breaks in a dose-dependent manner, the results of the present investigation showed that the combination of comet and CA assays provided a better choice for assessing the genotoxicity of inorganicHg.

The anticancer effect of phospho-tyrosol-indomethacin (MPI-621), a novel phosphoderivative of indomethacin: in vitro and in vivo studies

We have synthesized a novel derivative of indomethacin, phospho-tyrosol-indomethacin (PTI; MPI-621), and evaluated its anticancer efficacy in vitro and in vivo. PTI inhibited the growth of human colon, breast and lung cancer cell lines 6-30-fold more potently than indomethacin. In vivo, in contrast to indomethacin that was unable to inhibit colon cancer xenograft growth, PTI inhibited the growth of colon (69% at 10mg/kg/day, P < 0.01) and lung (91% at 15mg/kg/day, P < 0.01) subcutaneous cancer xenografts in immunodeficient mice, suppressing cell proliferation by 33% and inducing apoptosis by 75% (P < 0.05, for both). Regarding its pharmacokinetics in mice, after a single intraperitoneal injection of PTI, its plasma levels reached the maximum concentration (Cmax = 46 μM) at 2h (Tmax) and became undetectable at 4h. Indomethacin is the major metabolite of PTI, with plasma Cmax = 378 μM and Tmax = 2.5h; it became undetectable 24h postadministration. The cellular uptake of PTI (50-200 μM) at 6h was about 200-fold greater than that of indomethacin. Regarding its safety, PTI had no significant genotoxicity, showed less gastrointestinal toxicity than indomethacin and presented no cardiac toxicity. Mechanistically, PTI suppressed prostaglandin E2 production in A549 human lung cancer cells and strongly inhibited nuclear factor-κB activation in A549 xenografts. These findings indicate that PTI merits further evaluation as an anticancer agent.

Cytotoxic and Genotoxic Effects of Silver Nanoparticles on Primary Syrian Hamster Embryo (SHE) Cells

Silver-nanoparticles (NPs) have become increasingly common in various applications, raising some safety concerns. In this study, the cytotoxic and genotoxic effects of silver-NPs on primary Syrian hamster embryo (SHE) cells were investigated. Cell viability was assessed using a methyl tetrazolium (MTT) assay, and genotoxic potential was evaluated using a cytokinesis-block micronucleus (CBMN) assay. The results showed that dose-dependent cytotoxicity was induced after 24 h of exposure to silver-NPs. The micronucleation frequency (MNF) also increased significantly in a dose-dependent manner (P < 0.05), suggesting that silver-NPs induce genotoxicity. This is consistent with an increased MNF observed in primary SHE cells. The results of cell cycle analysis indicate that the cell cycles became arrested in the GO/G1 phase and that the S phase shortened after only 8 h of silver-NP exposure, suggesting that DNA replication had been inhibited, which in turn inhibited further cell proliferation. The rate of late-stage apoptosis increased after 12 h of silver-NP exposure, and both early- and late-stage apoptosis were obviously increased after 72 h of exposure than in controls. This study demonstrated that silver-NPs could induce strong cytotoxicity and significant genotoxicity in primary SHE cells and that this is probably due to silver-NP-induced apoptosis and the inhibition of cell proliferation.

Genotoxicity evaluation of stearic acid grafted chitosan oligosaccharide nanomicelles

Stearic acid grafted chitosan oligosaccharide (CSO-SA) nanomicelles could be promptly internalized into cancer cells; therefore, it is regarded as a promising drug carrier for cancer therapy. However, the toxicity of CSO-SA is not clear. In the present study, the genotoxic effects of CSO-SA nanomicelles (with high substitution degree of SA, 42.6±3.8%) were evaluated with a battery of genotoxicity assays. Mutagenicity was not found in Ames Salmonella/microsome mutagenicity assay (Ames test), while mild but definite positive results were observed in mouse bone marrow micronucleus assay and single cell gel electrophoresis (SCGE or comet assay) in A549 cells. CSO-SA was also found to induce apoptosis and oxidative stress through the induction of reactive oxygen species (ROS) in a dose-dependent manner in A549 cells. Preincubation with the free radical scavenger N-acetyl-l-cysteine (NAC) decreased the intracellular ROS level and alleviated the DNA damage in A549 cells. Expression levels of cleaved poly ADP-ribose polymerase (PARP), caspase-9 and caspase-3, markers of apoptosis, were significantly higher in CSO-SA treated cells. In conclusion, these results suggested significant genotoxicity of high doses of CSO-SA nanomicelles in vivo and in vitro. Oxidative stress was, at least partially, the possible mechanism underlying the genotoxicity induced by CSO-SA.

Study on the genotoxicity of HA/ZrO2 composite particles in vitro

To evaluate the genotoxicity of the HA/ZrO2 composite particles by using the micronucleus test (MNT) in vitro. HA/ZrO2 composite particles prepared by sintering at high temperature and pressure, that used powder of HA and ZrO2 of different proportions, were compared with pure HA particles and pure ZrO2 particles. The effect of the composite particles on cell proliferation of rabbit mesenchymal stem cells, and its the genotoxicity to rabbit mesenchymal stem cells were detected by MNT method. The MTT test showed that both pure HA particles and composite particles which contained HA promoted cell proliferation of rabbit mesenchymal stem cells, while pure ZrO2 particles did not, and there was a significant difference (P<0.05). The MNT test showed no significant difference between the HA group and the negative control group (P>0.05), but a significant difference between the HA group and the positive control group (P<0.05). The difference between the ZrO2 group and the negative control group was significant (P<0.01), while the difference between the ZrO2 group and the positive control group was insignificant (P>0.05). The genotoxicity of the HA/ZrO2 composite particle increased with a higher proportion of ZrO2 and an increase in the concentration of the composite, and the 30wt.% HA/70% ZrO2 composite with 200μg/mL concentration showed significant genotoxicity (P<0.01).