Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Alleviate Age-Related Insomnia in Rats by Suppressing Neuronal Ferroptosis in the Hippocampal Dentate Gyrus.

Age-related insomnia (ARI) is becoming increasingly prevalent among the elderly and remains inadequately addressed by conventional pharmacotherapy, prompting growing interest in stem cell–based alternatives. The present study investigated whether exosomes derived from umbilical cord mesenchymal stem cells (UCMSC-Exos) ameliorate ARI by suppressing hippocampal neuronal ferroptosis. UCMSCs were isolated from Sprague–Dawley rats on gestational day 21, and UCMSC-Exos were purified from passage 3 supernatants by ultracentrifugation. Transmission electron microscopy, nanoparticle tracking analysis, and western blotting confirmed characteristic exosomal morphology with a mean diameter of 118.4 nm, positive expression of TSG101, CD9, and CD81, and absence of Calnexin. Following tail vein injection of DiD-labeled UCMSC-Exos in rats, DiD signals were traceable for 21 days. An ARI model was established in adult male rats using D-galactose combined with para-chlorophenylalanine, and animals were randomized into Sham, ARI, ARI-UCMSC-Exos, and ARI-Fer-1 groups. Morris water maze, elevated plus maze, open field tests, and electroencephalography demonstrated that UCMSC-Exos reversed behavioral deficits and prolonged total and slow-wave sleep. Hematoxylin-eosin, Nissl, and Golgi staining revealed restored dentate gyrus neurons with increased dendritic number and length, while transmission electron microscopy showed improved synaptic and mitochondrial ultrastructure. Prussian blue staining, ELISA, and western blotting further indicated that UCMSC-Exos reduced Fe3+, glutamate, and reactive oxygen species while elevating cysteine, glutathione, GPX4, 5-HT, and BDNF. Collectively, UCMSC-Exos alleviate sleep disturbance in ARI rats by inhibiting hippocampal neuronal ferroptosis, highlighting their therapeutic potential for ARI.