REANIMA scientists have identified a new factor specifically expressed in a subset of pro-regenerative cardiomyocytes in fishes that spontaneously regenerate their hearts. On the other side, they have generated genetic tools and molecular approaches that allow the classification and functional testing of different populations of cardiac fibroblasts in regenerative animals (axolotl and zebrafish). The specific involvement of these cell populations in heart regeneration are currently being analyzed by the members of the consortium. REANIMA scientists have also established new approaches for single-cell mRNA sequencing from adult cardiomyocytes, a procedure that currently bears important limitations in the scientific community.
Moving along the translational pathway, REANIMA scientists have screened hundreds of factors affecting sarcomere protein degradation. As a result, they isolated two factors essential in the regulation of sarcomere stability and cardiomyocyte proliferation. The factors identified have been studied in a mouse model of myocardial infarction (MI), showing positive results. After thorough study in the rodent model, these factors will be ready to progress along the translational pipeline towards large animal models testing. Working in the mouse model, REANIMA scientists have been able to test the role of Erbb2 in restoring heart function during the chronic phase on MI. The results obtained were very positive, indicating that even in a remodelling heart with a consolidated scar, this treatment is effective.
Moving into areas of research closer to the clinical application, Agrin efficacy in improving heart function after AMI in the pig has been tested in two independent studies in different laboratories. One of the studies yielded positive results in terms of safety and efficacy of the treatment and has been published. The second study has been completed and its results are currently been analyzed. The effects of Agrin have been assessed as well in a model of chronic MI in rats, yielding an improved function following the treatment. On the other side, mir-199a has been tested in a model of chronic MI in pigs. In this case, the results were negative in terms of improving heart function and, in addition, produced fatal arrhythmias due to long-term expression of the miRNA. Given that previous results indicated a clear pro-regenerative effect of miRNA-199a during AMI, new ways are being explored for the transient delivery of this pro-regenerative factor in the pig model. To this end, REANIMA scientists have developed a novel nanoparticle formulation that efficiently delivers the concentrated miRNA, and demonstrated efficacy in vitro and in the mouse heart.
Finally, REANIMA scientists have generated a new model of cardiac injury in human engineered heart tissues. Using cryoinjury as an approach, they showed the loss of myocardial tissue and the inability of the damaged muscle to regain contractile force following cryoinjury. This model provides for the first time a functional platform for testing regenerative treatments in human myocardial tissue.