Abstract Body (Do not enter title and authors here): Background: Cardiac aging is a major global health challenge today. The aim of this study was to investigate the interventional effects and potential mechanisms of human umbilical cord mesenchymal stem cell exosomes (hUCMSC-exos) on the heart of naturally aging mice.
Methods: Twenty-two-month-old C57BL6J mice were used as a wild-type natural aging control group (WTA, n=10); the experimental group was the exosome-intervened aging group ( WTAEX, n=10), and 0.1 mL of hUCMSC-exos (concentration: 1x10¹⁰particles/particle) was injected in the tail vein once a week for eight weeks. The interventional effects of hUCMSC-exos on cardiac aging were comprehensively evaluated from multiple dimensions, including morphology histopathology, Proteomic and β-hydroxybutyrylation (Kbhb) modification omics. In addition, an AMPKα2 knockout mouse model was constructed to investigate the effect of AMPKα2 on exosome intervention in cardiac aging.
Results: Western blot showed that hUCMSC-exos reversed the expression of senescence-associated molecules (p53, p21, and p16, as well as telomerase reverse transcriptase (TERT)) in senescent mice. Echocardiography showed that hUCMSC-exos significantly decreased ratio of the early to late diastolic mitral flow velocity (E/A); H & E and Masson staining showed that hUCMSC-exos ameliorated the structural disturbances in senescent cardiomyocytes and mitochondria, in addition to increased adenosine triphosphate (ATP) production. Proteomics analyses revealed that 234 proteins were up-regulated in WTAEX group hearts, of which, AMPKα2 was significantly elevated. The KEGG functional enrichment analysis showed that hUCMSC-exos upregulated differentially expressed proteins (DEPs) involved in pathways such as hypertrophic cardiomyopathy, oxidative phosphorylation and TCA cycle. Kbhb modification omics identified 179 sites were down-regulated in 114 proteins. Furthermore, KEGG pathway enrichment analysis revealed that the downregulated Kbhb modified proteins are involved in pathways such as TCA cycle, fatty acid degradation, and glycolysis in WTAEX group. Knockdown of AMPKα2 reduces the ameliorative effect of hUCMSC-exos on cardiac aging.
Conclusions: HUCMSC-exos targets AMPKα2 to modulate the level of Kbhb modification of mitochondrial proteins, increase ATP production, and improve diastolic function in naturally cardiac aging mice. This finding provides a potential therapeutic strategy for the treatment of aging-associated cardiovascular diseases.