• biological barrier monitoring
• bioreactors
• cellular impedance
• engineering hydrogel viscoelasticity
• in-vitro models
• mechanical properties monitoring
• viscoelasticity

The aim of this work of thesis was to contribute to the engineering of physiologically relevant in-vitro models with the design of systems able to mimic and monitor the dynamic environment of cellular constructs. These advanced models are emerging as a powerful solution to bridge the gap between basic and clinical research, currently hindered by the low predictivity and limited successful translation rate of animal models.
In particular, a cellular impedance-meter was designed and interfaced with a dual-flow bioreactor to monitor the electrical properties of biological barriers. Indeed, epithelial and endothelial tissue allow the separation of different compartments in the human body and are normally exposed to shear stress on both sides (e.g. blood and interstitial fluid flow).
The system was validated with an intestinal model, demonstrating that dynamic conditions contribute significantly to the tightness of the barrier. Possible applications of the system range from drug testing to the study of several pathologic conditions related with an alteration of barrier functions.
Since it is well known that mechanical properties of tissues dynamically evolve during growth, ageing or diseases like fibrosis, different methods were investigated to modulate spatial and temporal viscoelastic properties of hydrogel-based scaffolds. In order to monitor mechanical properties of cellular constructs in real-time, the MechanoCulture TR (MCTR) bioreactor was re-engineered in collaboration with the Canadian company CellScale. Finally, a model of liver fibrosis was implemented mimicking in-vitro the ‘healthy’-fibrotic transition with an enzymatic stiffening method and monitoring the mechanical properties of hepatocyte laden gels in the MCTR. The results obtained represent a first step towards physiologically relevant models useful in the understanding of fibrosis mechanobiological mechanisms and progression or in the study of antifibrotic drugs.
In conclusion, during the PhD, advanced models with integrated sensing for the real-time monitoring of electrical and mechanical properties of cell construct were designed, tested and validated. The results obtained have relevant implications both in the medical field, contributing to the study of disease development, and in the pharmaceutic and cosmetic fields, providing reliable tools for testing chemical compounds and drugs.