Refining fibroblast-to-cardiomyocyte transdifferentiation protocols to explore emergent self- organization in cardiac cultures

Fibrotic scars post-myocardial infarction disrupt cardiac conduction, causing arrhythmias. We developed a minimized 4-component cocktail (CHIR99021/BMP4/Activin A/IWP2) for efficient fibroblast-to-cardiomyocyte transdifferentiation. The use of the developed four-component protocol allows achieving significant electromechanical activity and pronounced expression of cardiomyocyte markers, as evidenced by the 56–83% cells expressing α-actinin. The results show that partial transdifferentiation of fibroblast cells into cardiac ones is sufficient to restore cardiac tissue conductivity, while the efficiency exceeds the critical percolation threshold. Systemic delivery of components is safe, but requires further optimization, which will open up opportunities for localized delivery through smart substrates and combinations with cell therapy. Minimization of the transdifferentiation cocktail is not a compromise, but a strategic advantage that provides an optimal balance between functional efficiency and clinical applicability, including safety, delivery, and manufacturing.