Abstract 12585: Human Heart Progenitors Regenerate Porcine Hearts via Migration and Fibroblast Repulsionhuman Heart Regeneration by Cardiac Pmigration and Fibroblast Repulsion

Abstract

Human heart regeneration is one of the most critical unmet clinical needs at a global level. Muscular regeneration is hampered both by the limited renewing capacity of adult cardiomyocytes and the onset of cardiac fibrosis, resulting in reduced compliance of the tissue. Pluripotent stem cell strategies have proven efficacious for heart regeneration in rodents, pigs and primates, but approaches to specifically drive cell migration to the site of injury and inhibit subsequent fibrosis have been elusive. By virtue of human cardiac progenitor lineage tracing and single-cell transcriptomics, we uncover coordinated muscular regeneration in injured non-human primate heart bio-mimics. Remuscularization occured via directed migration of human ventricular progenitors to site of injury, concomittant fibroblast repulsion targeting fibrosis, and ultimately functional replacement of damaged cardiac muscle by differentiation and electromechanical integration. Single-cell RNAseq captured distinct capabilities, such as migration towards a CXCL12 gradient and fibroblast repulsion regulated by SLIT2/ROBO1 guidance in organizing cytoskeletal dynamics. Injection of human cardiac progenitors into hypo-immunogenic CAG-LEA29Y transgenic porcine hearts following radiofrequency ablation injury proved their chemotactic response and ability to generate a remuscularized scar in vivo . Transplantation of ~500 million cryopreserved human embryonic stem cell-derived progenitors vs cadiomyocytes similarly enhance cardiac function in pigs with myocardial infarctions. However, the risk of graft-associated ventricular arrhythmias from ectopic pacemaker automaticity shown by electroanatomical mapping is significantly lower in progenitor- compared to cardiomyocyte-treated hearts. Moreover, progenitor grafts exhibit larger CD31 + blood vessel networks and lower CD68 + immune cell infiltration. Our study demonstrates that inherent developmental programs within cardiac progenitors are sequentially activated in the context of disease, allowing the cells to sense, counteract injury and integrate into the host environment. As such, they may represent an ideal bio-therapeutic for functional heart rejuvenation.