AMPK-dependent maturation of hiPSC-derived cardiomyocytes induced by human cardiac fibroblast exosomes

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a promising therapy for ischemic cardiomyopathy, which is often secondary to hypertension but remain functionally immature. We investigated whether exosomes from human cardiac fibroblasts (hc-FB-EXOs) promote hiPSC-CMs maturation and improve their reparative efficacy after myocardial infarction (MI). hc-FB-EXOs were isolated from cultured fibroblasts. hiPSC-CMs were treated with hc-FB-EXOs or vehicle and assessed for morphology, sarcomeric organization, metabolism, and electrophysiology. RNA sequencing and Western blotting were used to explore mechanisms. In a mouse MI model, left ventricular function, infarct size, wall thickness, and graft density were evaluated after intramyocardial injection of hiPSC-CMs with or without hc-FB-EXOs. hc-FB-EXOs induced adult-like features in hiPSC-CMs, including increased cell size and sarcomere length, fetal-to-adult isoform switching of myosin and troponin, enhanced mitochondrial respiration, and a shift toward fatty acid-based oxidative metabolism. Electrophysiological maturation was evidenced by a higher peak sodium current density, faster upstroke velocity, and more mature action potential and field potential profiles. Transcriptomic and biochemical analyses identified activation of AMP-activated protein kinase (AMPK) signaling, with the modulation of downstream regulators of fatty acid oxidation. In vivo, co-delivery of hc-FB-EXOs with hiPSC-CMs improved the left ventricular ejection fraction, reduced the infarct size, and increased the graft density compared with those of hiPSC-CMs alone. hc-FB-EXOs promote the maturation of hiPSC-CMs via AMPK-mediated metabolic reprogramming and enhance their therapeutic benefit after MI. Cardiac fibroblast-derived exosomes may serve as a practical adjunct to optimize hiPSC-CMs-based therapy for ischemic cardiomyopathy.