Avaliação do papel multifacetado de microRNAs no combate à fibrose cardíaca

Fibrosis is transversal to virtually all forms of cardiac disease. Cardiac fibrosis ensues from an over-activation of cardiac fibroblasts and their differentiation into myofibroblasts, alongside an exacerbated deposition of extracellular matrix proteins (in particular, collagen), which leads to stiffening of the myocardium and, eventually, to pathological remodelling of the heart. Recent studies have shown that miRNAs control several features of cardiovascular diseases, (CVDs) including cardiac fibrosis. We recently performed a series of high-content microscopy functional screenings using genome-wide libraries of miRNA mimics to investigate, at the genome scale, the role of miRNAs on key phenotypes relevant to cardiac fibrosis, including human primary cardiac fibroblast proliferation, fibroblast activation/myofibroblast transdifferentiation, and deposition of fibrillar collagen. Building on these data and extensive validation, we selected 3 highly promising miRNAs (miR-377-5p, miR-5195-3p and miR-7113-5p), which will be the focus of this project. These miRNAs block fibroblast proliferation and collagen deposition, while exhibiting a differential effect on myofibroblast transdifferentiation (cf. Preliminary Data, unpublished); the selection of miRNAs that block collagen, while increasing or decreasing myofibroblast transdiffferentiation, provides a unique opportunity to explore the role of this process in replacement vs. interstitial cardiac fibrosis. The MAIN GOAL of this project Is to evaluate the anti-fibrotic potential of miR-377-5p, miR-5195-3p and miR-7113-5p in advanced 3D multicellular human cardiac tissue models in vitro, and subsequently in pre-clinical models of replacement and interstitial fibrosis, alongside with the characterisation of the underlying mechanisms of action. This ambitious goal will be pursued through the achievement of 3 SPECIFIC OBJECTIVES that will be pursued in the 3 TASKS proposed, each representing a significant improvement of the knowledge in the field: 1. To identify the targets and characterize the molecular mechanisms underlying the effect of the selected miRNAs in fibrosis-related phenotypes; 2. To evaluate the anti-fibrotic effect of the selected miRNAs in Engineered Human Myocardium (EHM); 3. To determine whether in vivo modulation of the selected miRNAs can translate into a therapeutic benefit, using pre-clinical mouse models of replacement and interstitial cardiac fibrosis. We anticipate that the knowledge resulting from this research project will constitute a significant improvement beyond the state-of-the-art and pave the way to the development of novel anti-fibrotic therapies.