Nanoparticles (NPs) have gained a lot of interest in recent years due to their huge potential for
applications in industry and medicine. Their unique properties offer a large number of
attractive possibilities in the biomedical field, providing innovative tools for diagnosis of
diseases and for novel therapies. Nevertheless, a deep understanding of their interactions with
living tissues and the knowledge about their possible effects in the human body are necessary
for the safe use of nanoparticulate formulations.
The aim of this PhD project was to study in detail the interactions of therapeutic NPs with
living cells, including cellular uptake and release, cellular localization and transport across the
cell layers. Moreover, the effects of NPs on the cellular metabolic processes were determined
using adapted in vitro assays. We evaluated the biological effect of several NPs potentially
used in the biomedical field, including titanium dioxide (TiO2) NPs, 2-sized fluorescent silica
NPs, ultrasmall superparamagnetic iron oxide (USPIO) NPs, either uncoated or coated with
oleic acid or with polyvinylamine (aminoPVA) and poly(lactic-co-glycolic acid) -
polyethylene-oxide (PLGA-PEO) NPs.
We have found that the NPs were internalized by the cells, depending on their size, chemical
composition, surface coating and also depending on the cell line considered. The uptake of
aminoPVA-coated USPIO NPs by endothelial cells was enhanced in the presence of an
external magnetic field. None of the tested USPIO NPs and silica NPs was transported across
confluent kidney cell layers or brain endothelial cell layers, even in the presence of a
magnetic field. However, in an original endothelium-glioblastoma barrier model which was
developed, uncoated USPIO NPs were directly transferred from endothelial cells to
glioblastoma cells. Following uptake, TiO2 NPs and uncoated USPIO NPs were released by
the kidney cells, but not by the endothelial cells. Furthermore, these NPs induced an oxidative
stress and autophagy in brain endothelial cells, possibly associated with their enhanced
agglomeration in cell medium. A significant DNA damage was found in brain endothelial
cells after their exposure to TiO2 NPs.
Altogether these results extend the existing knowledge about the effects of NPs on living cells
with regard to their physicochemical characteristics and provide interesting tools for further
investigation. The development of the in vitro toxicological assays with a special
consideration for risk evaluation aims to reduce the use of animal experiments.