An innovative therapeutic treatment to stimulate cardiac regeneration through lipid nanoparticles-mediated miRNAs administration: from design to correlative morpho-functional characterization

During acute myocardial infarction (MI), up to 25% cardiomyocytes (CMs) in the left ventricle can die, which plays a major role in the progression to heart failure (HF). This loss is not compensated by new CM generation as, in adulthood, CMs lose their capability to proliferate. Recently, the host laboratory has proved that cardiac regeneration after MI can be stimulated by the therapeutic administration of various miRNAs in both mice (Eulalio et al., Nature, 2013) and pigs (Gabisonia et al., Nature, 2019). However, these studies also highlighted the safety issues related to the use of adeno-associated viruses for gene delivery. Here, we want to design a novel therapeutic treatment to regenerate infarcted hearts based on the administration of selected pro-proliferative miRNAs delivered through lipid nanoparticles, which have been recently approved clinically for other conditions and offer an unprecedented translational possibility to stimulate cardiac regeneration. The effects of treatment will be comprehensively characterized, both functionally and structurally, at both cellular and organ levels, using a novel reporter mouse in which replicating cells become genetically labelled. We will monitor cardiac function and analyze the number of replicating CMs, as well as angiogenesis and molecular and cellular parameters related to HF. By taking advantage of my expertise, we will perform whole-organ, high-resolution 3D reconstructions of the regenerated hearts, employing cutting-edge optical imaging platforms (Olianti et al., PBMB, 2021). The spatial distribution and arrangement of proliferating CMs, connexins and fibrotic patches will be mapped and quantified in 3D. For each heart, structural information will be correlated to functional analyses.The findings of this project will provide novel and important information on the molecular, functional and structural correlates of cardiac regeneration, which is essential to support therapeutic development in this field.