Abstract 17357: Direct Cardiac Reprogramming Using Combinatorial Modified mRNA

Abstract

Introduction: Despite various clinical modalities, ischemic heart disease remains among the leading causes of mortality and morbidity worldwide. The elemental problem is the immense loss of cardiomyocytes (CMs) post-myocardial infarction (MI). Reprogramming non- cardiomyocytes (non-CMs) into cardiomyocyte (CM)-like cells in vivo is a promising strategy for cardiac regeneration: however, the traditional viral delivery method hampered its application into clinical settings due to low and erratic transduction efficiency. Methods: We used a modified mRNA (modRNA) gene delivery platform to deliver different stoichiometry of cardiac-reprogramming genes (Gata4, Mef2c, Tbx5 and Hand2) together with reprogramming helper genes (Dominant Negative (DN)-TGFβ, DN- Wnt8a and Acid ceramidase (AC)), named 7G, to induce direct cardiac reprogramming post myocardial infarction (MI). Results: Here, we identified 7G modRNA cocktail as an important regulator ofthe cardiac reprogramming. Cardiac transfection with 7G modRNA doubled cardiac reprogramming efficiency (57%) in comparison to Gata4, Mef2C and Tbx5 (GMT) alone (28%) in vitro . By inducing MI in our lineage tracing model, we showed that one-time delivery of the 7G-modRNA cocktail reprogrammed ~25% of the non-CMs in the scar area to CM- like cells. Furthermore, 7G modRNA treated mice showed significantly improved cardiac function, longer survival, reduced scar size and greater capillary density than control mice 28 days post-MI. We attributed the improvement in heart function post modRNA delivery of 7G or 7G with increased Hand2 ratio (7G-GMT Hx2) to significant upregulation of 15 key angiogenic factors without any signs of angioma or edema. Conclusions: 7G or 7G GMT HX2 modRNA cocktails boosts de novo CM-like cells and promotes cardiovascular regeneration post-MI. Thus, we highlight that this gene delivery approach not only has high efficiency but also high margin of safety for translation to clinics.