In vitro placental model optimization for nanoparticle transport studies

Abstract

Background

Advances in biomedical nanotechnology raise hopes in patient populations but may also raise questions regarding biodistribution and biocompatibility, especially during pregnancy. Special consideration must be given to the placenta as a biological barrier because a pregnant woman’s exposure to nanoparticles could have significant effects on the fetus developing in the womb. Therefore, the purpose of this study is to optimize an in vitro model for characterizing the transport of nanoparticles across human placental trophoblast cells.

Methods

The growth of BeWo (clone b30) human placental choriocarcinoma cells for nanoparticle transport studies was characterized in terms of optimized Transwell^® insert type and pore size, the investigation of barrier properties by transmission electron microscopy, tight junction staining, transepithelial electrical resistance, and fluorescein sodium transport. Following the determination of nontoxic concentrations of fluorescent polystyrene nanoparticles, the cellular uptake and transport of 50 nm and 100 nm diameter particles was measured using the in vitro BeWo cell model.

Results

Particle size measurements, fluorescence readings, and confocal microscopy indicated both cellular uptake of the fluorescent polystyrene nanoparticles and the transcellular transport of these particles from the apical (maternal) to the basolateral (fetal) compartment. Over the course of 24 hours, the apparent permeability across BeWo cells grown on polycarbonate membranes (3.0 μm pore size) was four times higher for the 50 nm particles compared with the 100 nm particles.

Conclusion

The BeWo cell line has been optimized and shown to be a valid in vitro model for studying the transplacental transport of nanoparticles. Fluorescent polystyrene nanoparticle transport was size-dependent, as smaller particles reached the basal (fetal) compartment at a higher rate.

Keywords:

• nanoparticles
• placenta
• BeWo cells
• transport
• model optimization
• nanotoxicology

Acknowledgments

The authors are grateful for funding provided through the NanoTEST Consortium, supported by the European Commission FP7 (Health-2007-2001.3-4, contract number 201335), and express thanks for the support of Maria Dusinska, Lucienne Juillerat, and Antonio Marcomini in their leadership roles within the NanoTEST Consortium. LC and MS acknowledge technical support from Sara Correia Carreira and also acknowledge that some of this work was carried out with the support of the Bristol Centre for Nanoscience and Quantum Information and the Wolfson Bioimaging Facility, University of Bristol. ER is supported by a research career development award (K12HD052023: Building Interdisciplinary Research Careers in Women’s Health Program, BIRCWH) from the National Institute of Allergy and Infectious Diseases (NIAID), the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and the Office of the Director (OD), National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIAID, NICHD, OD, or the National Institutes of Health.

Disclosure

The authors report no conflicts of interest in this work.