Ultra-Efficient Exosome-Guided Direct Reprogramming of Fibroblasts into Functional Cardiomyocytes [Quant-seq]

Direct lineage conversion holds great promise in the regenerative medicine field for restoring damaged tissues using functionally engineered counterparts. However, current methods of direct lineage conversion, even those employing virus-mediated transgenic expression of tumorigenic factors, are extremely inefficient (~25%). Thus, advanced methodologies capable of revolutionizing efficiency and addressing safety issues are key to clinical translation of these technologies. Here, we propose an exosome-guided, non-viral, direct-lineage conversion strategy to enhance transdifferentiation of fibroblasts to induced cardiomyocyte-like cells (iCMs). Exosomes produced during the cardiac differentiation process of embryonic stem cells (ESCs) are able to achieve extremely high reprogramming efficiency (>60%) by generating functional iCMs from mouse embryonic fibroblasts via a cardiac precursor-like stage rather than a pluripotent state. The resulting iCMs possess typical cardiac Ca2+ transients and electrophysiological features, and exhibit global gene expression profiles similar to those of cardiomyocytes. The optimized reprogramming conditions produce beating iCM clusters ~3-fold more efficiently than conventional methods. This is the first demonstration of the use of exosomes derived from ESCs undergoing cardiac differentiation as biomimetic tools to induce direct cardiac reprogramming with greatly improved efficiency, establishing a general, more readily accessible platform for broadly generating a variety of specialized somatic cells through direct lineage conversion. Quant-seq 3’ mRNA sequencing for gene expression analysis of MEF, iCMs at day 15, iCMs at day 30 and nCMs