Identification and quantification of gold engineered nanomaterials and impaired fluid transfer across the rat placenta via ex vivo perfusion

Abstract

Development and implementation of products incorporating nanoparticles are occurring at a rapid pace. These particles are widely utilized in domestic, occupational, and biomedical applications. Currently, it is unclear if pregnant women will be able to take advantage of the potential biomedical nanoproducts out of concerns associated with placental transfer and fetal interactions. We recently developed an ex vivo rat placental perfusion technique to allow for the evaluation of xenobiotic transfer and placental physiological perturbations. In this study, a segment of the uterine horn and associated placenta was isolated from pregnant (gestational day 20) Sprague-Dawley rats and placed into a modified pressure myography vessel chamber. The proximal and distal ends of the maternal uterine artery and the vessels of the umbilical cord were cannulated, secured, and perfused with physiological salt solution (PSS). The proximal uterine artery and umbilical artery were pressurized at 80 mmHg and 50 mmHg, respectively, to allow countercurrent flow through the placenta. After equilibration, a single 900 μL bolus dose of 20 nm gold engineered nanoparticles (Au-ENM) was introduced into the proximal maternal artery. Distal uterine and umbilical vein effluents were collected every 10 min for 180 min to measure placental fluid dynamics. The quantification of Au-ENM transfer was conducted via inductively coupled plasma mass spectrometry (ICP-MS). Overall, we were able to measure Au-ENM within uterine and umbilical effluent with 20 min of material infusion. This novel methodology may be widely incorporated into studies of pharmacology, toxicology, and placental physiology.

Keywords: Engineered nanomaterial; Gold nanomaterials; ICP-MS; Organ perfusion; Placenta.

Figure 1:

Schematic of placental perfusion methodology. Isolation of the uterine horn and placental until permits cannulation of the proximal uterine artery and umbilical vein; perfusion of these arteries allows for perfusion and countercurrent flow within the placenta. Cannulation of the distal uterine artery and umbilical artery allow for effluent collection for biochemical and physiological analyses.

Figure 2:

Representative images of placental morphology after ex vivo perfusion. (A) There was no identifiable histopathology associated with Au-ENM exposure or perfusion pressures in any of the samples (n=3). (B) Identification and visualization of Au-ENM particle deposition within the placenta after material infusion and placental perfusion using enhanced hyperspectral microscopy (CytoViva, Inc). While xenobiotic particles were identified in the control samples, these particles exhibit a different hyperspectral waveform compared to the Au-ENM samples.

Figure 3:

Quantification of Au-ENM concentration within the (A) uterine artery effluents and (B) fetal umbilical vein effluents over a 180-minute time course via ICP-MS analyses, normalized and compared to baseline. *p<0.05; ^Tp<0.1. (n=11)

Figure 4:

Measurement of (A) maternal fluid flow across the uterine artery or (B) fluid flow across the placenta to the fetal compartment after Au-ENM infusion. *p<0.05; ^Tp<0.1. compared to control values. (n=11)

Figure 5:

Total Au-ENM transfer after the perfusion experiment was complete via ICP-MS analyses. These represent the distribution of Au-ENM within the maternal effluents (time course samples pooled), uterine muscle and vasculature, placenta and fetal effluents (time course samples pooled). Data is represented as quantified deposition (left) and percentage of material collected (right).