Brain aging is a multifactorial process associated with oxidative stress, chronic neuroinflammation, and synaptic dysfunction, ultimately leading to cognitive decline and increased susceptibility to n Show more
Brain aging is a multifactorial process associated with oxidative stress, chronic neuroinflammation, and synaptic dysfunction, ultimately leading to cognitive decline and increased susceptibility to neurodegenerative disorders. Epigallocatechin gallate (EGCG) is a potent antioxidant and anti-inflammatory agent, but its therapeutic potential is limited by poor stability and bioavailability. In this study, a dual nano delivery system was developed by loading chitosan-EGCG nanoparticles into mesenchymal stem cell-derived exosomes (Ex-Chit-EGCG NPs) and evaluated for neuroprotective efficacy in a D-galactose-induced brain aging model. Intranasal administration of Ex-Chit-EGCG NPs significantly improved cognitive and locomotor performance compared with exosomes alone, as evidenced by enhanced outcomes in Y-maze and open field tests. Biochemical analyses revealed that Ex-Chit-EGCG NPs effectively reduced lipid peroxidation, restored glutathione levels, and reactivated the LKB1/AMPK/SIRT1 signaling pathway. Molecular investigations demonstrated upregulation of Nrf2, BDNF, and SIRT1 together with suppression of NF-κB and Iba-1 expression, indicating attenuation of oxidative and inflammatory responses. Histopathological and immunohistochemical evaluations confirmed these findings, showing preservation of cortical and brain stem architecture with marked reductions in neuronal necrosis, gliosis, BAX, GFAP, and NLRP3 expression. Collectively, the results demonstrate that Ex-Chit-EGCG NPs exert superior neuroprotective effects compared with exosomes alone, highlighting the therapeutic advantage of combining EGCG with chitosan nanocarriers and exosomal delivery. This dual nanotherapeutic strategy offers a promising and non-invasive approach for mitigating brain aging and holds potential for translation into therapies targeting age-related neurodegenerative disorders. Show less