Abstract

Objective This study aimed to investigate the mechanisms by which the ultrafiltrate of Radix Angelicae Sinensis and Hedysari (RAS-RH) and its active component formononetin alleviate X-ray radiation-induced injury in rat cardiac microvascular endothelial cells (CMECs) through modulation of cardiac telocytes (TCs)-mediated paracrine signaling. Methods An in vitro radiation-induced CMEC injury model was established. Mitochondrial function, proliferation, migration, angiogenesis, and apoptosis were assessed using transmission electron microscopy, flow cytometry, mitochondrial probes, 5-ethynyl-2′-deoxyuridine staining, wound-healing and tube-formation assays, Western blotting, and immunofluorescence. Single-cell RNA sequencing, network pharmacology, molecular docking, and molecular dynamics simulations were used to identify formononetin as the key active component of RAS-RH and to predict its regulatory targets. Reverse transcription quantitative real-time polymerase chain reaction and in situ hybridization further validated the underlying mechanisms. Results X-ray radiation decreased the mitochondrial membrane potential, increased reactive oxygen species levels, and upregulated the expression of mitochondrial fission-related proteins: mitochondrial fission 1 protein (Fis1), dynamin-related protein 1,and mitochondrial fission factor, thereby inducing mitochondrial dysfunction. These changes suppressed endothelial cells (ECs) proliferation, migration and tube formation and downregulated the expression of endothelial growth factors, such as vascular endothelial growth factor, basic fibroblast growth factor, and angiopoietin-2. In contrast, formononetin, as the active component of RAS-RH upregulated androgen receptor (AR) transcription in TCs and enhanced the expression and paracrine release of TCs-derived miR-151a-5p, which subsequently downregulated Fis1 expression in ECs and inhibited Fis1-mediated excessive mitochondrial fission. Through these mechanisms, formononetin