Functional and morphological study of cells in connected culture in response to interactions associated with nanoparticles

The improvement of in vitro and in vivo models for tissue engineering, pharmacology, or metabolic studies, is largely requested. In fact, while in vitro models are usually preferred due to their convenience and compatibility with the 3Rs, unfortunately they lack biochemical interactions, for instance cell-cell cross-talk or important bio-barriers leading to non-physiologically relevant results. The aim of this thesis is to develop a new in vitro system able to recreate the main barrier through ingestion, the intestinal epithelium as well as a connected target organs, the vascular endothelium and the liver. The thesis is focused on the study of nanoparticle (NP) fate after ingestion, the ability of NPs to cross the intestinal barrier and the effects on relevant target tissues. In order to achieve this aim simplified models were firstly used so that the complexity of the system could be increased stepwise to include additional cell types, more complex 3D models of tissues, and more sophisticated and specific tests of cellular responses to the presence of nanoparticles. The system developed is a new body-on-a-plate device able to study the physiologically relevant doses that actually reach the systemic circulation after intestinal absorption. It has a microfluidic flow which transports messaging molecules from cell to cell and stimulates them with a constant low shear stress. Hence, the results obtained with this new model were compared with data generated in conventional static cell cultures in order to validate the system and gain a better insight on the systemic effects of NP toxicity. Besides the study of the toxicity of nanoparticles of industrial and environmental interest, this thesis demonstrates the importance of advanced in vitro testing, pointing out the differences in results from standard simple cultures with respect to those obtained from more relevant physiological model.