Smart modular scaffolds (SMSs) for the realisation of 3D in-vitro organ models

This thesis is focused on engineering a pathophysiological 3D in-vitro liver model able to mimic healthy hepatic tissue as well as ageing and fibrotic processes. The classical Tissue Engineering approach (based on cells, scaffold and bioreactor) was followed for the bottom-up development of the 3D in-vitro liver model. In particular, since an ideal scaffold should mimic most of the properties of the native extracellular matrix (ECM), several decellularisation procedures were investigated to obtain liver matrices (dECMs) which were physicochemically and mechano-structurally characterised to derive the ideal design specification for ECM-mimicking scaffolds. Since the biomechanical environment plays a critical role in regulating hepatic cell response and directing the development of tissue fibrosis, attention was focused on the mechanical properties of decellularised hepatic tissue. Then, hydrogel-based smart modular scaffolds (SMSs) for hepatic cell encapsulation were designed to obtain supports that mimic the stiffness of healthy liver ECM and can subsequently be enzymatically stiffened to recreate fibrotic environments. The enzymatic stiffening was designed to recapitulate the enzyme-mediated hardening typical of ageing and fibrotic processes in hepatic tissue. A transparent bioreactor (TB) was subsequently designed and realised for dynamic cultivation and real-time monitoring of the hepatocyte-laden SMS constructs. Finally, experiments with HepG2 liver cells encapsulated within SMSs and cultured in the TB were conducted to assess the suitability of both SMSs and TB developed during this thesis for engineering pathophysiological 3D in-vitro liver models. The latter can be used for a vast range of applications, such as drug development, prediction of the ADMET (i.e. adsorption, distribution, metabolism, elimination and toxicology) properties and the clinical efficacy of new potential drugs and treatments, mechanistic studies, chemical testing and disease modelling, contributing to the reduction of both experimental costs and the number of animals currently used in research.