Psoralen Enhances Direct Cardiac Reprogramming via PPARα Activation and Promotion of Mitochondrial Fission

BACKGROUNDCell-based therapy is a promising strategy for heart repair and regeneration. However, its clinical application has been hampered by the low efficiency of cell direct reprogramming and the immature state of the inducing cells. Developing novel strategies to enhance direct reprogramming efficiency and yield mature functional cardiomyocytes remains a critical challenge. METHODSWe evaluated the effect of Psr on cardiac reprogramming using RepSox and Forskolin (RF) as the baseline cocktail. Reprogramming efficiency, cardiomyocyte marker expression, and calcium handling were assessed by RT-qPCR, immunofluorescence. Ultrastructural features were examined by transmission electron microscopy. Metabolic profiles were analyzed using Seahorse assays. Transcriptomic changes were explored by RNA sequencing, followed by pathway and protein-protein interaction analyses. A myocardial infarction (MI) mouse model was used for in vivo validation. RESULTSSupplementation with Psr (10 M) markedly enhanced the induction of induced cardiomyocytes (iCMs), leading to earlier appearance of beating clusters (day 1 vs. day 6-8), improved sarcomere organization, robust calcium transients, and higher energy metabolism. Transcriptomic profiling identified activation of the PPAR signaling pathway, with PPAR, RXRG, and UCP1 as central regulators. Mechanistically, Psr promoted mitochondrial fission, thereby facilitating metabolic remodeling essential for cardiomyocyte maturation. In vivo, RF+Psr treatment significantly improved cardiac function and reduced fibrosis after MI compared to RF alone. CONCLUSIONPsr enhances direct cardiac reprogramming by activating PPAR signaling and promoting mitochondrial fission. These findings provide a novel mechanistic framework and suggest psoralen as a promising natural enhancer for cardiac regeneration strategies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/681288v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@13a5d27org.highwire.dtl.DTLVardef@b9cce5org.highwire.dtl.DTLVardef@3afef8org.highwire.dtl.DTLVardef@1398972_HPS_FORMAT_FIGEXP M_FIG C_FIG