UCMSC-Exos treatment significantly reduced in jaw bone marrow mesenchymal stem cells.
Treatment with UCMSC-Exos decreased the number of senescent cells in JBMMSCs, indicated by reduced SA-β-gal-positive cells.
Key proteins associated with cellular senescence (p53, p21, p16) and inflammatory markers (IL-6, TNF-α) were downregulated following treatment.
Improvements in cellular functions such as proliferation, migration, and osteogenic differentiation were observed in UCMSC-Exos-treated JBMMSCs compared to controls.
UCMSC-Exos restored autophagy in JBMMSCs by modulating the PI3K/AKT/mTOR signaling pathway.
In aged rat models, UCMSC-Exos treatment enhanced bone repair in calvarial defects.
Simplified
BACKGROUND: The age-related functional decline of bone marrow mesenchymal stem cells significantly impairs bone regeneration capacity. derived from umbilical cord mesenchymal stem cells (UCMSCs) have emerged as promising therapeutic agents in regenerative medicine and anti-aging research due to their bioactive cargo and low immunogenicity. This study investigated the rejuvenating potential of UCMSCs-derived exosomes (UCMSC-Exos) on senescent jaw bone marrow mesenchymal stem cells (JBMMSCs) and their ability to enhance bone repair in aged rats.
METHODS: Senescent JBMMSCs were treated with UCMSC-Exos, and their effects on , proliferation, migration, and osteogenic capability were assessed using senescence-associated beta-galactosidase (SA-β-gal) staining, CCK8 assays, scratch assays, alizarin red S staining, alkaline phosphatase staining, RT-qPCR, ELISA and western blotting. The underlying mechanisms were explored through western blot analysis of autophagy markers and PI3K/AKT/mTOR pathway. For in vivo evaluation, calvarial defect models were established in aged rats, and the bone repair efficacy of UCMSC-Exos was assessed by micro-CT, histological staining, immunohistochemical staining for OCN and ALP, and immunofluorescence staining for OPN and OSX.
RESULTS: UCMSC-Exos treatment markedly attenuated cellular senescence in JBMMSCs, as demonstrated by decreased SA-β-gal-positive cells and downregulation of key senescence-associated proteins (p53, p21, and p16) and pro-inflammatory cytokines (IL-6 and TNF-α). The exosome-treated cells showed significant improvements in proliferative capacity, migratory ability, and osteogenic differentiation potential compared to untreated controls. Mechanistically, UCMSC-Exos restored autophagy through modulation of the PI3K/AKT/mTOR signaling pathway, as demonstrated by altered protein expression. In rat calvarial defect models, UCMSC-Exos treatment resulted in better bone repair in aged rats.
CONCLUSIONS: This study demonstrated that UCMSC-Exos could rejuvenate senescent JBMMSCs by activating autophagy via the regulation of PI3K/AKT/mTOR pathway, and enhance bone repair in aged rats. UCMSC-Exos hold potential as a cell-free therapeutic tool for anti-aging treatments and regenerative medicine, particularly for age-related skeletal disorders.
Key numbers
13.83±3.07%
Bone Volume/Total Volume in Aged Rats
Bone volume in the Aged + Exo group after UCMSC-Exos treatment
6
SA-β-gal-positive Cells Reduction
Number of experimental replicates for SA-β-gal staining
5
Calcium Deposition Increase
Number of experimental replicates for osteogenic differentiation assays
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Declarations. Ethics approval and consent to participate: Animal Ethics declaration: All experimental procedures involving animals were ethically approved by the Animal Welfare Ethics Committee of Beijing MDKN Biotechnology Co., Ltd. (Approval number: MDKN-2024-072; Date of approval: April 20, 2024; Title of the approved project: “Exosomes derived from umbilical cord mesenchymal stem cells alleviate jaw bone marrow mesenchymal stem cells senescence and promote osteogenic differentiation”), and were in compliance with the Guidelines for ethical review of animal welfare of Laboratory animals issued by the China National Standardization Management Committee (publication No. GB/T35892-2018). This work has been reported in line with the ARRIVE guidelines 2.0. There were no ethical conflicts associated with this manuscript. Other Ethics declaration: The research utilized UCMSCs were obtained from iCell Bioscience Inc. (HUM-iCell-e009, Shanghai, China), which were ethically sourced and complied with relevant regulatory standards. Consent for publication: All authors confirm their consent for publication. Competing interests: The authors declare no competing interests. Clinical trial number: Not applicable.
