miR-21-5p Enriched Exosomes from Human Embryonic Stem Cells Promote Osteogenesis via YAP1 Modulation

Abstract

Purpose: To investigate the osteogenic potential of human embryonic stem cell-derived exosomes (hESC-Exos) and their effects on the differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs). Methods: hESC-Exos were isolated and characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blotting. hUCMSCs were cultured with hESC-Exos to assess osteogenic differentiation through alizarin red staining, quantitative PCR (qPCR), and Western blotting. miRNA profiling of hESC-Exos was performed using miRNA microarray analysis. In vivo bone regeneration was evaluated using an ovariectomized rat model with bone defects treated with exosome-loaded scaffolds. Results: hESC-Exos significantly promoted the osteogenic differentiation of hUCMSCs, as evidenced by increased alizarin red staining and the upregulation of osteogenesis-related genes and proteins (ALP, RUNX2, OCN). miRNA analysis revealed that miR-21-5p is a key regulator that targets YAP1 and activates the Wnt/β-catenin signaling pathway. In vivo, hESC-Exos enhanced bone repair in ovariectomized rats, as demonstrated by increased bone mineral density and improved bone microarchitecture compared to those in controls. Conclusion: hESC-Exos exhibit significant osteogenic potential by promoting the differentiation of hUCMSCs and enhancing bone regeneration in vivo. This study revealed that the miR-21-5p-YAP1/β-catenin axis is a critical pathway, suggesting that the use of hESC-Exos is a promising therapeutic strategy for bone regeneration and repair.