Exosome therapy protects the hippocampus in mice exposed to chronic methamphetamine: Insights into angiogenic and inflammatory signaling pathways.

Methamphetamine (Meth) exposure leads to cognitive dysfunction and neurodegeneration in the hippocampus. Considering exosome therapy as a new treatment approach for neurological diseases, the current study proposed to investigate the effects of mesenchymal stem cell (MSC)-derived exosomes on hippocampal angiogenesis, inflammation, and cognitive function in Meth-treated mice. Meth (5 mg/kg) was injected daily for 30 days, and MSC-derived exosomes (100 μg per dose) were administered intravenously for three consecutive days after the Meth exposure. The Y-maze and Novel Object Recognition Test (NORT) evaluated spatial and recognition memory, while motor function was assessed through the Open Field Test (OFT). Results showed that exosome therapy improved both spatial and recognition memory. Additionally, the time spent in the center of the open field and the distance traveled significantly increased following treatment in Meth-exposed animals. Furthermore, exosome therapy promoted hippocampal angiogenesis and neurogenesis, as indicated by increased expression levels of HIF-1α, VEGF, and DCX, respectively, and also reduced Meth-induced hippocampal inflammation, evidenced by decreased TNF-α expression. These findings demonstrate that exosome therapy enhances cognitive function, encourages hippocampal angiogenesis, and diminishes inflammation in the hippocampus of Meth-treated mice.