Jane F. Rasco

Surface charge and dosage dependent potential developmental toxicity and biodistribution of iron oxide nanoparticles in pregnant CD-1 mice

Iron oxide nanoparticles have attracted much attention because of their potential applications, such as drug delivery, biomedical imaging, and photocatalysis. Due to their small size and the potential to cross the placental barrier, the risk to pregnant women and the developing fetus from exposure to nanoparticles is of great concern. The developmental toxicity and biodistribution of a single dose versus multiple doses of iron oxide nanoparticles with positive or negative surface charges were investigated in vivo. Multiple doses of positively-charged nanoparticles given over several days resulted in significantly increased fetal deaths and accumulation of iron in the fetal liver and placenta. These results indicate both positively and negatively charged iron oxide nanoparticles have the ability to cross the placenta and accumulate in the fetus, though greater bioaccumulation and toxicity was observed with a positively-charged surface coating.

Effects of maternal restraint stress and sodium arsenate in mice.

Either maternal restraint stress or sodium arsenate treatment during pregnancy can cause adverse effects on the mouse conceptus. The current study assessed the effects of both factors administered concurrently. Five treatment groups were used initially: (1) vehicle (H2O) control [C], (2) feed/water deprived [FWD], (3) sodium arsenate [SA], (4) restraint only [R], and (5) sodium arsenate plus restraint [SA+R]. A sixth group, arsenate plus feed/water deprived [SA+FWD], was added later, along with (7) a concurrent arsenate-only control [SAC]. Mated female CD-1 mice in Groups 3, 5, 6, and 7 were injected ip with sodium arsenate (20 mg/kg) on gestation day (GD) 9 (plug = day 1). Group 5 mice were restrained for 12 h beginning immediately after dosing. Groups 4 and 5 were restrained in the supine position from 9:00 a.m. to 9:00 p.m. on GD 9; FWD mice were deprived during that time. All females were killed on GD 18 and subjected to teratologic examination. Significantly increased exencephaly and decreased fetal weight were seen in SA+R Group fetuses. The incidence of supernumerary ribs was significantly higher in the SA+R Group than in the SA Group but did not differ from the R Group. These results add to the evidence that maternal stress combined with a chemical teratogen may have a greater effect on the conceptus than would exposure to either agent alone.

Developmental toxicity assessment of the ionic liquid 1-butyl-3-methylimidazolium chloride in CD-1 mice

The effects of prenatal exposure of mice to the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) were studied because of the potential for human exposure as a result of water or soil contamination from industrial effluent or accidental spills. After exposure to the IL, fetal weight was significantly decreased at the two highest dosages (P≤ 0.01). Malformations were also somewhat more numerous at the highest dosage, suggesting that [C4mim]Cl may be teratogenic, although the apparent increase was not statistically significant. Maternal toxicity was also present, as shown by a dose-dependent increase in maternal morbidity and mortality during the course of treatment. Therefore from these results, [C4mim]Cl appears to be developmentally toxic at maternally toxic dosages, although the mechanism is unknown.

Short- and Long-Term Effects of Prenatal Exposure to Iron Oxide Nanoparticles: Influence of Surface Charge and Dose on Developmental and Reproductive Toxicity

Iron oxide nanoparticles (NPs) are commonly utilized for biomedical, industrial, and commercial applications due to their unique properties and potential biocompatibility. However, little is known about how exposure to iron oxide NPs may affect susceptible populations such as pregnant women and developing fetuses. To examine the influence of NP surface-charge and dose on the developmental toxicity of iron oxide NPs, Crl:CD1(ICR) (CD-1) mice were exposed to a single, low (10 mg/kg) or high (100 mg/kg) dose of positively-charged polyethyleneimine-Fe2O3-NPs (PEI-NPs), or negatively-charged poly(acrylic acid)-Fe2O3-NPs (PAA-NPs) during critical windows of organogenesis (gestation day (GD) 8, 9, or 10). A low dose of NPs, regardless of charge, did not induce toxicity. However, a high exposure led to charge-dependent fetal loss as well as morphological alterations of the uteri (both charges) and testes (positive only) of surviving offspring. Positively-charged PEI-NPs given later in organogenesis resulted in a combination of short-term fetal loss (42%) and long-term alterations in reproduction, including increased fetal loss for second generation matings (mice exposed in utero). Alternatively, negatively-charged PAA-NPs induced fetal loss (22%) earlier in organogenesis to a lesser degree than PEI-NPs with only mild alterations in offspring uterine histology observed in the long-term.

Developmental toxicity assessment of thermoresponsive poly(N-isopropylacrylamide-co-acrylamide) oligomers in CD-1 mice.

BACKGROUND Although polymers and hydrogels are used successfully in biomedical applications, including implants and drug delivery devices, smaller molecular weight oligomers, such as those investigated here, have not been extensively studied in vivo. Poly(N-isopropylacrylamide-co-acrylamide), or P(NIPAAm-co-AAm), has a unique thermoresponsive behavior and is under investigation as a novel drug delivery system for metastatic cancer treatment. To date, no studies have been published regarding the safety of P(NIPAAm-co-AAm) to the conceptus. METHODS From gestation days (GD) 6-16, pregnant CD-1 mice were dosed via i.p. injection with aqueous solutions containing 500, 750, or 1,000 mg/kg/d P(NIPAAm-co-AAm). Dams were sacrificed on GD 17 and their litters were examined for abnormalities. RESULTS P(NIPAAm-co-AAm) caused no statistically significant difference in maternal weight gain or percent resorbed or dead fetuses compared to control values, but fetal weight was significantly decreased in the two highest dosage groups. CONCLUSIONS At the highest dosages employed, maternal exposure to P(NIPAAm-co-AAm) was associated with decreased fetal weight. However, as the estimated human exposure levels for persons using this system would be some 1,500-fold lower than the lowest dosage administered in this study, the authors feel that this oligomer was not shown to pose a biologically significant risk at relevant human dosages.

Differential effect of restraint procedure on incidence of restraint-stress-induced rib fusion in CD-1 mice

In an investigation of the effects of specific maternal stressors on development of the conceptus, pregnant mice were exposed to restraint stress on gestation day 9 (plug = day 1). Mated females were either unrestrained (C), unrestrained and food/water deprived (FWD), or restrained with surgical tape in a supine position for 12 h by one of two methods: I. 1-inch wide tape reaching from each shoulder across the body to the opposite thigh, or II. 1-inch wide tape placed over one shoulder, across the thorax, and over the opposite shoulder and similar tape placed over each thigh and across the intervening pelvic area. For both methods, an additional tape was placed across the tail and a 2-inch wide tape secured the upper abdominal area. There were 32 to 62 litters in each treatment group, and all fetuses were examined on day 18 for gross and skeletal defects. With regard to rib fusion, the percentage of affected fetuses and litters was increased (P < or = 0.05) by Method I (3.5% and 27%, respectively) vs. Method II. (0.5% and 4%), C (0.1% and 1%), or FWD (0%). Incidences of supernumerary ribs, however, did not differ between the restrained groups but were higher in both such groups than in the FWD and C groups. These results suggest that different methods of restraint may result in differences in incidence of rib fusion. Such data suggest that development of the offspring of stressed dams may be significantly influenced by what might appear to be minor differences in the stress techniques used.

Comment on: Padmavathi et al. (2010) Chronic Maternal Dietary Chromium Restriction Modulates Visceral Adiposity: Probable Underlying Mechanisms. Diabetes;59:98–104

Padmavathi et al. (1) examined the effects of two diets, AIN-93G and AIN-93G with the chromium (Cr) removed from the mineral mixture normally added to the diet. The authors considered the diet lacking the added Cr to be “restrictive” in terms of this element. The normal diet contained 1.56 mg Cr/kg diet, while the diet lacking the added Cr contained 0.51 mg Cr/kg diet. We believe that the “restrictive” diet is not restrictive and …

Transdermal Bioavailability in Rats of Lidocaine in the Forms of Ionic Liquids, Salts, and Deep Eutectic

Tuning the bioavailability of lidocaine was explored by its incorporation into the ionic liquid lidocainium docusate ([Lid][Doc]) and the deep eutectic Lidocaine·Ibuprofen (Lid·Ibu) and comparing the transdermal absorption of these with the crystalline salt lidocainium chloride ([Lid]Cl). Each form of lidocaine was dissolved in a vehicle cream and topically applied to Sprague-Dawley rats. The concentrations of the active pharmaceutical ingredients (APIs) in blood plasma were monitored over time as an indication of systemic absorption. The concentration of lidocaine in plasma varied between applied API-based creams, with faster and higher systemic absorption of the hydrogen bonded deep eutectic Lid·Ibu than the absorption of the salts [Lid]Cl or [Lid][Doc]. Interestingly, a differential transdermal absorption was observed between lidocaine and ibuprofen when Lid·Ibu was applied, possibly indicating different interactions with the tissue components.

Monocarboxylate Transporters are not Responsible for Cr3+ Transport from Endosomes

Cr3+, similar to Fe3+, is transported into cells primarily via endocytosis as the metal-transferrin complex. As Cr3+ ions are not readily reduced under biological conditions, the ion cannot be transported from endosomes by the same mechanism as iron that utilized divalent metal ion transporters. Cr3+ has been hypothesized to potentially be transported as small ligand complexes with a free carboxylate functionality by monocarboxylate transporters (MCT), in a similar fashion to that proposed for Al3+. Consequently, mouse C2C12 muscle cells were utilized to determine if Cr3+ is potentially transported by MCT by examining the effects of MCT inhibitors on Cr and Fe transport and subcellular distribution when the metals are added as their transferrin complexes. The results suggest that Cr is not primarily transported by MCT from the endosomes to the cytosol, and that another mechanism for this transport needs to be identified.

The Potential of Cr3 [Triaqua‐μ3‐Oxo‐Hexa‐μ‐Propionatotrichromium(III) Chloride] to Reduce Birth Defects in the Offspring of Diabetic CD‐1 Mice

Diabetes mellitus is a growing concern worldwide and leads to multiple complications during pregnancy. Pharmacologic doses of chromium (Cr) have been linked with improving insulin sensitivity and other positive benefits in the treatment of diabetes in animal models. By using streptozotocin induced hyperglycemia in female CD-1 mice, reproductive outcomes of diabetic and chromium-dosed diabetic females were examined. After dosing 10 mg/kg Cr in the form of triaqua-μ3 -oxo-hexa-μ-propionatotrichromium(III) chloride or Cr3 during gestation days 8-16 (GD8-GD16), all females were sacrificed on gestation day 17 (GD17) and examined for maternal weight gain. The fetuses were examined for gross malformations and for skeletal malformations. The offspring of Cr3-dosed females tended to have a reduction in the incidence of supernumerary ribs. While hyperglycemia still had negative impacts on the health of dams and their offspring, administration of Cr led to an apparent trend in the reduction in the number of malformations and incidence of supernumerary ribs compared to those of untreated diabetic mothers.