Ultraefficient extracellular vesicle–guided direct reprogramming of fibroblasts into functional cardiomyocytes

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 using virus-mediated transgenic expression of tumorigenic factors, are extremely inefficient (~25%). Thus, advanced methodologies capable of revolutionizing efficiency and addressing safety concerns are key to clinical translation of these technologies.

Researchers at Korea Institute of Science and Technology have developed an extracellular vesicle (EV)-guided, nonviral, direct lineage conversion strategy to enhance transdifferentiation of fibroblasts to induced cardiomyocyte-like cells (iCMs). The resulting iCMs have typical cardiac Ca²⁺ transients and electrophysiological features and exhibit global gene expression profiles similar to those of cardiomyocytes. This is the first demonstration of the use of EVs derived from embryonic stem cells undergoing cardiac differentiation as biomimetic tools to induce cardiac reprogramming with extremely high efficiency (>60%), establishing a general, more readily accessible platform for generating a variety of specialized somatic cells through direct lineage conversion.

Direct conversion of fibroblasts into functional cardiomyocytes

(A) Schematic illustration of EV-guided direct cardiac reprogramming. (B) Sarcomeric structure revealed by immunostaining for α-MHC, cTnT, and α-actinin in single cells digested from iCM beating clusters. Scale bars, 40 μm. (C and D) Comparison of cardiac reprogramming efficiency with that of previously described protocols. (C) Fluorescence-activated cell sorting (FACS) analyses of α-MHC⁺ cells at day 20 in EV/CS, virus (Oct4/SCPF), and small molecule (CRFVPT) groups. Abbreviations of small molecules are provided in table S2. (D) Number of beating clusters at day 20 in OCT4/SCPF, CRFVPT, and EV/CS groups.