Extracorporeal cardiac shock wave stimulation enhances the therapeutic efficacy of intravenously delivered endothelial colony-forming cells via PI3K/AKT signaling in a rat myocardial infarction model

Abstract Background Extracorporeal cardiac shock wave (ECSW) therapy enhances the function of endothelial colony-forming cells (ECFCs), but whether it can serve as a preconditioning strategy to enhance myocardial infarction (MI) therapy remains unclear. This study investigated the efficacy and mechanism of intravenously delivered ECSW-preconditioned ECFCs (SW-ECFCs) in a rat MI model. Methods ECFCs were isolated from the bone marrow of ApoE -/- rats and fully characterized. RNA sequencing of control ECFCs versus SW-ECFCs revealed significant enrichment of the PI3K/AKT pathway. We therefore performed a series of in vitro functional assays on these cells, including Transwell migration, Matrigel tube formation, CCK-8 proliferation, flow cytometric apoptosis analysis, and VEGF-A ELISA. . The role of the PI3K/AKT pathway was interrogated using the inhibitor LY294002. Subsequently, an acute MI model was established in ApoE -/- rats via left anterior descending coronary artery ligation. Rats were randomized into four groups: MI + PBS, MI + ECFCs, MI + SW-ECFCs, and MI + LY294002-pretreated SW-ECFCs (LY-SW-ECFCs), with sham-operated rats as controls. Comprehensive evaluations included echocardiography, serum injury biomarkers, TTC, and histopathological (H&E, Masson) staining, immunohistochemical detection of cardiomyocyte apoptosis and p-eNOS, immunofluorescence assessment of ECFC homing and vascular markers (CD31, α-SMA, VEGF-A), tissue/plasma nitric oxide measurement, and Western blot analysis of PI3K/AKT signaling proteins. Results Transcriptomic analysis revealed significant enrichment of the PI3K/AKT pathway in SW-ECFCs. Functionally, ECSW enhanced ECFCs migration, tube formation, proliferation, and VEGF-A secretion, while reducing apoptosis; these effects were largely abolished by PI3K inhibition. In vivo, serum levels of CK, CK-MB, and LDH were significantly elevated in all MI groups compared to the Sham group ( P < 0.01), indicating comparable initial injury. However, no significant differences were observed among treatment groups ( P > 0.05). SW-ECFCs transplantation significantly improved cardiac function, reduced infarct size, fibrosis, and apoptosis, and enhanced angiogenesis ( P < 0.05). These benefits were associated with increased levels of p-AKT, p-eNOS, and BCL-2 protein as well as nitric oxide content, while suppressing the expression of cleaved caspase-3 ( P < 0.05). Crucially, all these therapeutic benefits were largely abolished by PI3K inhibition. Conclusion In conclusion, this study demonstrates that preconditioning ECFCs with ECSW significantly enhances their therapeutic efficacy for myocardial infarction, improving both cardiac function and structural repair. These benefits are mediated primarily through activation of the PI3K/AKT signaling pathway, which augments cell homing, paracrine activity, and survival, thereby providing a novel and promising strategy for cardiac regeneration.