Recreating biological barriers in a microfluidic system: applications of a new bioreactor

The need to develop increasingly faithful in vitro models capable of representing human organs and tissues under both physiological and pathological conditions is becoming pressing. Every year, countless topical and oral formulations are tested in the laboratory to evaluate their biodistribution, efficacy, safety, and potential toxicity. It is clear that the more accurately a laboratory model reflects the in vivo situation, the more informative and predictive the data obtained during this preclinical phase will be for the subsequent stages of research. In this way, with more robust preliminary data, the number of animals required in later research phases can be minimized, thus respecting the principle of the “3Rs” (Replace, Reduce, Refine). In an effort to meet this need, our research group has developed in recent years a dynamic culture model of tissue explants that has proven capable of slowing normal tissue degradation. In this way, our system provides a time window in which the explant responds to relevant stimuli in a manner comparable to the in vivo system, preserving cellular and extracellular components, and more generally the normal structural and ultrastructural morphology of the tissue. This model, which we define as a bioreactor, has the potential to bridge the gap between simplistic in vitro models and complex in vivo models. In our bioreactor, we have demonstrated improved preservation of human skin explants for up to 72 hours compared to the commonly used static model. This advanced system has allowed us to develop several experimental models, such as the creation of inflammatory skin models, the study of transcutaneous transport of various nanocarriers, and the evaluation of the effects of different formulations on human skin. Moreover, thanks to the modular nature of our bioreactor, we are developing experimental models involving different tissue types that require an environment as physiologically similar as possible to that of their anatomical origin. Our group has indeed set the goal of demonstrating the system’s ability to preserve intestinal and urinary bladder explants. Although this brings a huge number of challenges, it also opens up a wide range of potential applications of the model. Preliminary data are nonetheless encouraging and motivate us to continue our studies in this area. In addition to carrying out my work at the Section of Anatomy and Histology, Department of Neurosciences, Biomedicine and Movement Sciences of the University of Verona, I have had the opportunity to conduct experimental phases at the “Institute of Cell Biology, Faculty of Medicine” of the University of Ljubljana (Slovenia) and at the “Plants for Human Health Institute” of the North Carolina State University in Kannapolis (USA). Furthermore, I have participated in both national and international conferences, both as an oral presenter and a poster presenter. This doctoral thesis aims to collect the work carried out over these years.