Osterix mRNA Enrichment in Small Extracellular Vesicles Derived From Osteogenically Induced ADSCs: A Promoter of Osteogenic Differentiation in BMSCs

Osteogenic differentiation of bone marrow stem cells (BMSCs) is essential for bone tissue regeneration and repair. However, this process is often hindered by an unstable differentiation influenced by local microenvironmental factors. While small extracellular vesicles (sEVs) derived from osteogenically induced adipose mesenchymal stem cells (ADSCs) reportedly can promote osteogenic differentiation of BMSCs, the underlying molecular mechanisms remain incompletely understood. In this study, we investigated the mRNA expression profile of ADSC-sEVs⁺ and explored the role of specific mRNAs in the osteogenic differentiation of BMSCs. We first validated the osteogenic induction activity of ADSC-sEVs⁺ through both in vitro and in vivo experiments. Using reverse transcription polymerase chain reaction, we compared mRNA expression between ADSC-sEVs⁺ and ADSC-sEVs and further assessed the impact of specific mRNAs on the differentiation of BMSCs through a series of in vitro experiments. One of our key findings was that osterix mRNA was highly enriched in ADSC-sEVs⁺, which significantly enhanced alkaline phosphatase staining and upregulated downstream osteoblastic markers in BMSCs. Both overexpression and knockdown experiments confirmed that osterix mRNA is a critical signalling molecule that facilitates the differentiation of BMSCs into osteoblasts through ADSC-sEVs⁺. This finding expands our understanding of the molecular mechanisms underlying the osteogenic differentiation of BMSCs and offers a promising strategy for targeted osteoblastic differentiation in clinical applications.