Dottorato in MORFOGENESI E INGEGNERIA TISSUTALE

Titolo della tesi: X-MET, a muscle engineered tissue as a tool for basic research and regenerative medicine

Tissue engineering is an emerging field of research focused on the development of bioartificial substitutes for organs and tissues, which can, in turn, be applied in regenerative medicine, pharmaceutical, diagnostic, and basic research to elucidate fundamental mechanisms of cell functions and to investigate the molecular mechanisms underpinning disease onset and progression. We have previously generated an in vitro bioengineered three-dimensional vascularized skeletal muscle tissue, named eX-vivo Muscle Engineered Tissue (X-MET), which displays several morpho-functional properties of an in vivo muscle; it is able to contract spontaneously as well as to respond to electrical stimulation. The general aim of the thesis’s project was to further define, throughout three specific aims, the mechanical properties of X-MET and to disclose the functional plasticity of X-MET, subjected to mechanical stimuli. At first, we characterized the maximum shortening velocity, the maximum power, and the values of force and velocity at which X-MET develops the maximum power. Secondly, we contributed to better define the potential use of X-MET as an in vitro model for the preliminary testing and screening of drugs and molecules involved in disease onset and progression. We cultured X-MET under different conditions, mimicking cancer cachexia and aging and analyzed the molecular mechanisms involved in the myogenic program and in the maintenance of the muscle phenotype. Finally, based on the evidence that X-MET shows a synchronous and spontaneous contraction, we defined the functional plasticity of X-MET triggered by mechanical stimuli. Of note, it was observed that the 3D culture system and the applied mechanical tension induce the onset of cardiac muscle stiffness within X-MET, triggering the switch/remodeling from skeletal muscle to cardiac-like phenotype. Interestingly, transplanted X-MET was able to functional rescue the infarcted myocardium. For these features, X-MET can be considered a useful experimental tool for in vitro and in vivo studies to analyze homeostatic processes in a more complex in vitro model, for drug screening, and in regenerative medicine to restore, maintain, or improve tissue function.