Nanoparticles and spermatogenesis: how do nanoparticles affect spermatogenesis and penetrate the blood-testis barrier

Testicular biodistribution of 450 nm fluorescent latex particles after intramuscular injection in mice

The significant expansion in the use of nanoparticles and submicron particles during the last 20 years has led to increasing concern about their potential toxicity to humans and particularly their impact on male fertility. Currently, an insufficient number of studies have focused on the testicular biodistribution of particles. The aim of our study was to assess the distribution of 450 nm fluorescent particles in mouse testes after intramuscular injection. To this end, testes were removed from 5 groups of 3 mice each at 1 h (H1), 4 days (D4), 21 days (D21), 45 days (D45) and 90 days (D90) after the injection of 7.28 × 10⁹ particles in the tibialis anterior muscles of each mouse. We examined histological sections from these samples by epifluorescence microscopy and confocal microscopy and identified testicular biodistribution of a small number of particles in groups H1, D4, D21, D45 and D90. Using CD11b immunostaining, we showed that particles were not carried into the testis by macrophages. The intratesticular repartition of particles mainly followed testicular vascularization. Finally, we found some particles in seminiferous tubules but could not determine if the blood-testis barrier was crossed.

Immunomodulatory effects in the spleen-injured mice following exposure to titanium dioxide nanoparticles

Immune injuries following the exposure of titanium dioxide nanoparticles (TiO₂ NPs) have been greatly concerned along with the TiO₂ NPs are widely used in pharmacology and daily life. However, very little is known about the immunomodulatory mechanisms in the spleen-injured mice due to TiO₂ NPs exposure. In this study, mice were continuously exposed to 2.5, 5, or 10 TiO₂ NPs mg kg(-1) body weight for 90 days with intragastric administration to investigate the immunomodulatory mechanisms in the spleen. The findings showed that TiO₂ NPs exposure resulted in significant increases in spleen and thymus indices, and titanium accumulation, in turn led to histopathological changes and splenocyte apoptosis. Furthermore, the exposure of TiO₂ NPs could significantly increase the levels of macrophage inflammatory protein (MIP)-1α, MIP-2, Eotaxin, monocyte chemotactic protein-1, interferon-γ, vascular cell adhesion molecule-1, interleukin-13, interferon-γ-inducible protein-10, migration inhibitory factor, CD69, major histocompatibility complex, protein tyrosine phosphatase, protein tyrosine kinase 1, basic fibroblast growth factor, Fasl, and GzmB expression, whereas markedly decrease the levels of NKG2D, NKp46, 2B4 expression involved in immune responses, lymphocyte healing and apoptosis. These findings would better understand toxicological effects induced by TiO₂ NPs exposure.

The effect of zinc oxide nanoparticles on mouse spermatogenesis

OBJECTIVE

To evaluate the effects of zinc oxide nanoparticles on mouse spermatogenesis.

METHODS

Thirty two adult male NMRI mice were used. Experimental Groups (ZNP-1-ZNP-3) received one of the following treatments daily for 35 days: 5, 50 and 300 mg/kg zinc oxide nanoparticles respectively. Control group received only distilled water. Epididymal sperm parameters, testicular histopathology, morphometric analysis and spermatogenesis assessments were performed for evaluation of the zinc oxide nanoparticles effects on testis.

RESULTS

Epididymal sperm parameters including sperm number, motility and percentage of abnormality were significantly changed in 50 and 300 mg/kg zinc oxide nanoparticles treated mice (p < 0.01). Histopathological criteria such as epithelial vacuolization, sloughing of germ and detachment were significantly increased in 50 and 300 mg/kg zinc oxide nanoparticles treated mice (p < 0.001). 300 mg/kg zinc oxide nanoparticles induced formation of multinucleated giant cells in the germinal epithelium. 50 and 300 mg/kg zinc oxide nanoparticles also caused a significant decrease in seminiferous tubule diameter, seminiferous epithelium height and maturation arrest (p < 0.001).

CONCLUSION

Zinc oxide nanoparticles act as testicular toxicant and further studies are needed to establish its mechanism of action upon spermatogenesis.

Titanium dioxide nanoparticle-induced testicular damage, spermatogenesis suppression, and gene expression alterations in male mice

Although titanium dioxide nanoparticles (TiO2 NPs) have been demonstrated to accumulate in organs resulting in toxicity, there is currently only limited data regarding male reproductive toxicity by TiO2 NPs. In this study, testicular damage and alterations in gene expression profiles in male mice induced by intragastric administration of 2.5, 5, and 10mg/kg body weight of TiO2 NPs for 90 consecutive days were examined. Our findings showed that TiO2 NPs can cross the blood-testis barrier to reach the testis and accumulate therein, which, in turn, results in testicular lesions, sperm malformations, and alterations in serum sex hormone levels. Furthermore, microarray analysis showed that 70 genes with known functions were up-regulated, while 72 were down-regulated in TiO2 NPs-exposed testes. Of the altered gene expressions, Ly6e, Adam3, Tdrd6, Spata19, Tnp2, and Prm1 are involved in spermatogenesis, whereas Sc4mol, Psmc3ip, Mvd, Srd5a2, Lep, and Cyp2e1 are associated with steroid and hormone metabolism. Hence, the production and application of TiO2 NPs should be carried out cautiously, especially by humans of reproductive age.

Gold nanoparticles elevate plasma testosterone levels in male mice without affecting fertility

ω-Methoxy and ω-aminoethyl poly(ethylene glycol)-modified 14-nm gold nanoparticles can accumulate in mouse testes, pass through the blood-testis barrier, and enter germ cells. Furthermore, PEG-NH2 @AuNP accumulate more easier in the testes and increase plasma T levels. However, these two gold nanoparticle types have no effect on male fertility, fetal survival, or fetal 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.

How to optimize the benefits of computer assisted sperm analysis in experimental toxicology

Exposure at the working place to various substances, that may affect semen quality is possible and should be investigated in detail. One appropriate method for this is computer-assisted sperm analysis (CASA) which offers multiple benefits in comparison to manual evaluation. However, several pitfalls exist, which make the evaluation of data obtained from CASA difficult to interpret. In the present commentary, we focus on these problems, show some examples, and try to define minimum standards which should be taken into consideration whenever working with computer-assisted sperm analysis.

Silver nanoparticles effects on epididymal sperm in rats

The motivation of our study was to examine the acute effects of intravenously administered a single bolus dose of silver nanoparticles (AgNPs) on rat spermatogenesis and seminiferous tubules morphology. In the treated rats compared to the vehicle treated control animals, the experiments revealed a size-dependent (20nm and 200nm), dose-dependent (5 and 10mg/kg body mass) and time-dependent (24h, 7 and 28days) decrease the epididymal sperm count measured by histological methods. In parallel AgNPs injection increased the level of DNA damage in germ cells, as measured by alkaline comet assay. Histological examination of the testes showed change in the testes seminiferous tubule morphometry in 200nm Ag NPs treated rats. No change of body weight, adipose tissue distribution and the frequency of abnormal spermatozoa was observed. Twenty nanometers AgNP appeared to be more toxic than 200nm ones.