RNA-sequencing-based elucidation of the mechanism underlying aFGF mediated regulation of BMSCs via the PI3K-AKT pathway and its implications for rotator cuff injury repair.

BACKGROUND: Rotator cuff injury is a common clinical musculoskeletal issue with poor tendon-bone healing and high re-tear rates, posing therapeutic challenges. Acidic fibroblast growth factor (aFGF) has drawn wide attention for promoting angiogenesis, wound healing, and metabolic regulation. Bone marrow mesenchymal stem cells (BMSCs) enhance rotator cuff tendon-bone healing, making them ideal for tissue engineering repair. However, how aFGF regulates BMSCs and the involved signaling pathways in this repair process remain unclear. METHODS: Rabbit BMSCs were isolated and identified via flow cytometry for surface markers. Their osteogenic and adipogenic differentiation capacities were evaluated using Alizarin Red S (ARS) and Oil Red O staining, respectively. RNA sequencing (RNA-seq) was utilized to identify differentially expressed genes (DEGs) between aFGF-treated and control groups. DAVID database was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, while String database combined with Cytoscape software was employed to construct the protein-protein interaction (PPI) network. Finally, protein levels, cell proliferation, migration, angiogenic capacity, and osteogenic differentiation along with expression of osteogenic factors and chondrogenic genes were detected by Western blot, CCK-8, wound healing assay, tube formation assay, and alkaline phosphatase (ALP)/ARS staining and qRT-PCR, respectively. RESULTS: BMSCs were identified by high CD44/CD90 expression, low CD34/CD45 expression, and osteogenic/adipogenic differentiation potential. RNA-seq revealed 370 DEGs (158 upregulated, 212 downregulated). GO and KEGG pathway analyses identified significant terms, with prominent enrichment of the PI3K-AKT pathway. Furthermore, a PPI network illustrated DEG interactions. Mechanistically, aFGF treatment increased PI3K/AKT phosphorylation, enhanced BMSC proliferation, migration, angiogenesis and osteogenic differentiation, and upregulated osteogenic factors and chondrogenic genes, while these effects were attenuated by the PI3K inhibitor LY294002. CONCLUSION: aFGF modulated the differential gene expression in BMSCs by activating the PI3K-AKT signaling pathway, thereby promoting BMSCs' proliferation, migration, angiogenesis, and osteogenic differentiation. This mechanism provides a novel theoretical basis and potential therapeutic targets for rotator cuff injury management.