CD271+ Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Promote Angiogenesis via miR-124-3p Mediated PGF Targeting

<title>Abstract</title> <p>Background Endometriosis, affecting approximately 10% of reproductive-age women, is critically dependent on angiogenesis for ectopic lesion establishment and growth. While exosomes from mesenchymal stem cells (MSCs) exhibit pro-angiogenic properties, the functional heterogeneity of MSC subpopulations and their distinct angiogenic mechanisms remain poorly understood. CD271 marks a UCMSC subpopulation with enhanced regenerative potential, yet its role in exosome-mediated angiogenesis remains unexplored. Methods Exosomes were isolated from CD271 + UCMSCs via ultracentrifugation and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blotting. End.3 endothelial cells were treated with UCMSC-Exos or CD271 + UCMSC-Exos, and functional angiogenesis was assessed by scratch wound healing, Transwell migration, and tube formation assays. miRNA cargo was profiled by qRT-PCR, and miR-124-3p inhibition experiments were performed to confirm functional specificity. Putative miR-124-3p targets were identified using miRDB, TargetScan, and the HARRIS_HYPOXIA gene set, and validated by dual-luciferase reporter assay, western blotting, and PGF overexpression rescue experiments. Public transcriptomic datasets (GSE25628) were analyzed for external validation. Results CD271 + UCMSC-Exos were efficiently internalized by End.3 cells and significantly enhanced cell migration and tube formation compared with UCMSC-Exos. miR-124-3p was enriched in CD271 + UCMSC-Exos. Dual-luciferase reporter assays confirmed that miR-124-3p directly targets the 3'-UTR of PGF, leading to post-transcriptional suppression of PGF protein expression. PGF overexpression reversed this effect. miR-124-3p targets were enriched in angiogenesis-related KEGG pathways (HIF-1, VEGF, Rap1; all FDR &lt; 0.05). External validation in endometriosis tissues (GSE25628) confirmed PGF downregulation in ectopic lesions (log2FC = -0.705) with, while angiogenic markers including VEGFA, KDR, and FLT1 were upregulated in the same lesions. Conclusion CD271 + UCMSC-Exos promote angiogenesis through delivery of miR-124-3p, which directly targets PGF in endothelial cells. External transcriptomic validation supports the clinical relevance of this axis in endometriosis, suggesting therapeutic potential.</p>