Conditioned Extracellular Vesicles From Dedifferentiated Fat Cells Enhanced Bone Regeneration

Bone regeneration remains a major challenge in the field of oral and craniofacial medicine. Our previous study demonstrated that extracellular vesicles (EVs) derived from dedifferentiated fat cells (DFATs) promoted bone regeneration in vitro for the first time. This study aimed to further investigate the bone repair potential of conditioned extracellular vesicles (Cond-EVs) derived from DFATs in vivo and elucidate their downstream molecular regulatory mechanisms. DFATs were cultured using the ‘ceiling culture method’, and the secreted EVs were extracted by ultracentrifugation. Their effects on BMSCs proliferation, migration and osteogenic differentiation was verified. An EVs/ Gelatin methacryloyl (GelMA) hydrogel complex was constructed to verify its effect on repairing critical bone defects in rat skulls. Differential miRNAs of EVs before and after osteogenic induction pretreatment were screened by high-throughput sequencing to explore the molecular mechanism. DFATs-derived conditioned EVs (Cond-EVs) could promote the proliferation, migration and osteogenic differentiation of BMSCs. In vivo results showed that hydrogel-loaded Cond-EVs could significantly promote bone tissue regeneration at the rat skull defect site. After osteogenic induction pretreatment, miR-214-3p was significantly upregulated in DFATs-derived EVs, which relieved the negative regulation of osteogenic differentiation by CXXC5. DFATs-derived Cond-EVs promoted osteogenic differentiation of BMSCs by regulating the miR-214-3p/CXXC5 axis. These results may provide a new therapeutic target for the repair of craniofacial bone defects.