Direct Reprogramming Induces Vascular Regeneration Post Muscle Ischemic Injury.

Overview

Reprogramming non-cardiomyocytes (non-CMs) into cardiomyocyte (CM)-like cells is a promising strategy for cardiac regeneration in conditions such as ischemic heart disease. Here, we used a modified mRNA (modRNA) gene delivery platform to deliver a cocktail of four cardiac-reprogramming genes (Gata4 (G), Mef2c (M), Tbx5 (T) and Hand2 (H)) together with three reprogramming-helper genes (Dominant Negative (DN)-TGFβ, DN-Wnt8a and Acid ceramidase (AC)), termed 7G-modRNA, to induce CM-like cells. We showed that 7G-modRNA reprogrammed 57% of CM-like cells in vitro. Through a lineage-tracing model, we determined that delivering the 7G-modRNA cocktail at the time of myocardial infarction reprogrammed ∼25% of CM-like cells in the scar area and significantly improved cardiac function, scar size, long-term survival and capillary density. Mechanistically, we determined that while 7G-modRNA cannot create de-novo beating CMs in vitro or in vivo, it can significantly upregulate pro-angiogenic mesenchymal stromal cells markers and transcription factors. We also demonstrated that our 7G-modRNA cocktail leads to neovascularization in ischemic-limb injury, indicating CM-like cells importance in other organs besides the heart. modRNA is currently being used around the globe for vaccination against COVID-19, and this study proves this is a safe, highly efficient gene delivery approach with therapeutic potential to treat ischemic diseases.