Dottorato in MEDICINA MOLECOLARE

Titolo della tesi: Role of the extracellular matrix in human pathophysiologies

The extracellular matrix (ECM) is a complex network of fibers composed mainly of structural and fibrous proteins such as collagens and proteoglycans, which give it strength and plasticity. Both the composition of the ECM and the molecular structure are significantly modified during the repair of damaged tissues as well as in the progression of various diseases such as tumors and dystrophies. Recently many researches have attributed to the ECM features, the responsibility of modifying the transcriptomic profile of entire physiological systems, in pathological conditions. The development of advanced technologies applied to medicine, supported by innovative biomaterials, can provide significant insights into the knowledge of pathologies, recapitulating human three-dimensional pathological systems in vitro, included in a pathological ECM. Recently, it has been demonstrated that in triple negative breast cancer (TNBC) both the molecular and physical components of the tumor ECM are able to inhibit the permeabilization of the tumor mass by cytotoxic CD8+ T cells. Therefore, the main objective of the first part of the project was to create an investigation tool, recapitulating the physical characteristics of the tumor ECM in which to study the induced transcriptomic perturbation in human T lymphocytes. Our data showed that it is sufficient to increase the stiffness of the ECM, recapitulating the tumor microenvironment, to induce the physical, functional and molecular remodeling of CD8 T lymphocytes, significantly altering their immune belligerence. The second part of this work concerned the generation of a bio-printable natural hydrogel, derived from decellularized dystrophic porcine myocardium, to study the harmful cellular perturbations affecting the heart, in Duchenne Muscular Dystrophy (DMD). To this end, for the first time, we generated a pathological bio-printable hydrogel, which recapitulates the molecular composition and physical properties characteristic of the dystrophic cardiac ECM. Then, fibroblasts, induced pluripotent stem cells (iPSC)-derived cardiomyocytes and embryonic stem cells (ESC)-derived neurons were used to validate the functionality of the DMD bio-ink, demonstrating how the composition of the ECM is sufficient to induce molecular remodeling in cells. The need to investigate the role of the ECM in a pathological context led this study to develop revolutionary in vitro models, useful to overcome suboptimal translational models of ECM remodeling which could also be useful for testing the efficacy and toxicity of new drugs.