Effects of cadmium on preimplantation and early postimplantation mouse embryos in vitro with special reference to their trophoblastic invasiveness

Effects of Maternal Exposure to Cadmium Oxide Nanoparticles During Pregnancy on Maternal and Offspring Kidney Injury Markers Using a Murine Model

Nanoparticles (NP) are pervasive in many areas of modern life, with little known about their potential toxicities. One commercially important NP is cadmium oxide (CdO), which is used to synthesize other Cd-containing NP, such as quantum dots. Cadmium (Cd) is a well-known nephrotoxicant, but the nephrotoxic potential of CdO NP remains unknown, particularly when exposure occurs during pregnancy. Therefore, pregnant CD-1 mice were used to examine the effects of inhaled CdO NP (230 μg CdO NP/m(3)) on maternal and neonatal renal function by examining urinary creatinine and urinary biomarkers of kidney injury, including kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL). Inhalation of CdO NP by dams produced a fivefold increase in urinary Kim-1 with no marked effect on urinary creatinine levels. Kim-1 mRNA expression peaked by gestational day (GD) 10.5, and NGAL expression increased from GD 10.5 to 17.5. In addition, histological analyses revealed proximal tubular pathology at GD 10.5. Neonatal Kim-1 mRNA expression rose between postnatal days (PND) 7 and 14, with mammary glands/milk being the apparent source of Cd for offspring. These studies demonstrate that, similar to what is seen with other Cd forms, Cd associated with inhaled CdO NP results in renal injury to both directly exposed dam and offspring. As commercial uses for nanotechnology continue to expand throughout the world, risks for unintentional exposure in the workplace increase. Given the large number of women in the industrial workforce, care needs to be taken to protect these already vulnerable populations.

Cadmium associated with inhaled cadmium oxide nanoparticles impacts fetal and neonatal development and growth

One industrially important metal oxide nanoparticle (NP) is cadmium oxide (CdO). A study was performed using timed-pregnant CD-1 mice to determine if Cd associated with inhaled CdO NP could reach the placenta and adversely affect the developing fetus and/or neonate. Pregnant mice were exposed by inhalation either every other day to 100 μg of freshly generated CdO/m(3) (exposure 1) or daily to 230 μg CdO/m(3) (exposure 2). In each exposure, mice were exposed to CdO NP or carrier gas (control) for 2.5 h from 4.5 days post coitus (dpc) through 16.5 dpc. At 17.5 dpc, fetuses and placentas from both exposures 1 and 2 were collected, measured, and weighed. A subgroup from the second exposure was allowed to give birth, and neonates were weighed daily until weaning. Cadmium in the uterus and placenta, as well as in other maternal organs, was elevated in NP-treated mice, but was undetectable in fetuses at 17.5 dpc. Daily inhalation of 230 μg CdO NP/m(3) decreased the incidence of pregnancy (i.e., no evidence of implantation) by 23%, delayed maternal weight gain, altered placental weight, and decreased fetal length, as well as delayed neonatal growth. This study demonstrates that inhalation of CdO NP during pregnancy adversely affects reproductive fecundity and alters fetal and postnatal growth of the developing offspring.

In vitro comparative effect of Cd2+, Ni2+, and Co2+ on mouse postblastocyst development

Postblastocyst development of mouse preembryos was studied in vitro in order to determine direct effect of Cd2+, Ni2+, and Co2+ ions on embryogenesis during the peri-implantation stage. Uterine horns were flushed on Day 4 of pregnancy and expanded blastocysts were cultured for 4 days in the presence of micromolar Cd2+ (1.1-26.4), Ni2+ (0. 1-500) or Co2+ (1-200). Area of trophoblast outgrowth was measured and used as a quantitative toxicological endpoint. Hatching, attachment, outgrowth, and formation of inner cells mass were also registered. Significant adverse effect on the development stages were observed at 2.2 microM (Cd2+), at 10 microM (Ni2+), and at 100 microM (Co2+). Cd2+ and Co2+ decreased the area of trophoblast markedly at concentrations of 1.1 and 10 microM, respectively. Ni2+ exposure resulted in a slight increase at 10 microM followed by a marked reduction in the trophoblast area at 250 microM. Reduced proliferative ability of trophoblast cells may point to compromised invasiveness of the embryo. The lowest Cd2+ concentration (1.1 microM=0.25 microg/ml) significantly deteriorating trophoblast development was found to be lower than Cd levels ranging up to 0.512 microg/g, reported in clinical ovarian samples of occupationally nonexposed women. The morphological alteration and loss of cellular contacts in blastocysts induced by exposure to Cd2+, Ni2+, or Co2+ may adversely influence adhesion and recognition events and may disturb aggregation of mononuclear trophoblastic cells to multinucleated cells in the course of peri-implantation in vivo as well.

Human trophoblast cultures: models for implantation and peri-implantation toxicology

Implantation is the process that leads from blastocyst attachment to its embedding in the uterine wall. It is widely believed that failure of implantation is a common cause of pregnancy loss. Toxic agents can interfere directly with the process of implantation and therefore may account for unexplained implantation failures. Our knowledge of human implantation remains limited, mainly due to the lack of adequate experimental models. Studies of mechanisms underlying implantation in humans are by nature and for ethical reasons restricted to in vitro models. The aim of this review is to provide a critical evaluation of various in vitro models of implantation in humans, as well as essential background knowledge required for application of these models to the assessment of peri-implantation toxicity. Particular attention has been devoted to cell-cell and cell-matrix interactions as possible endpoints in the screening of toxic agents.

Zinc protection against cadmium effect on estrual cycle of Wistar rat

A single dose of cadmium chloride (2.2 mg/kg of body wt) increased the estrual cycle period about two times. This effect could be prevented by means of simultaneous administration of zinc at the same dose.