Ucmscs-Derived Exosomes Alleviate Jbmmscs Senescence And Restore Osteogenic Potential

To investigate the effects of exosomes derived from umbilical cord mesenchymal stem cells (UCMSCs) on the senescence and osteogenic capacity of jaw bone marrow mesenchymal stem cells (JBMMSCs) in aged rats. Young and aged JBMMSCs were isolated from 8-week-old and 20-month-old SD rats. Exosomes were obtained from UCMSCs using ultracentrifugation. The effects of exosomes on aged JBMMSCs were evaluated through: (1) CCK-8 and scratch wound assay; (2) β-galactosidase staining, PCR and WB (P16, P21, P53) for senescence; (3) ALP staining, Alizarin Red staining, PCR and WB (OPN, RUNX2, ALP) for osteogenic differentiation. Furthermore, autophagy-related proteins and key components of PI3K/AKT/mTOR pathway were examined. For in vivo experiments (approved by the Ethics Committee): Bilateral calvarial defects (5 mm diameter) were created in aged (20-month-old) and young (8-week-old) male SD rats (n=5 per group). In aged rats, exosomes were implanted into one defect site. Bone regeneration was assessed at 4 weeks by micro-CT, HE staining, Masson’s trichrome staining, and ALP immunohistochemistry. The exosomes significantly enhanced proliferation, migration and osteogenesis of senescent BMMSCs while attenuating cellular senescence. These beneficial effects may be mediated through PI3K/AKT/mTOR pathway-activated autophagy. In vivo results confirmed that exosome treatment effectively improved bone regeneration in aged rats. UCMSCs-Exos attenuated cellular senescence and enhanced osteogenic differentiation in aged JBMMSCs by activating autophagy through PI3K/AKT/mTOR pathway.