Exercise-induced plasma-derived extracellular vesicles increase adult hippocampal neurogenesis
Aerobic exercise enhances cognition in part by increasing adult hippocampal neurogenesis, angiogenesis, and astrogliogenesis. Since hippocampal atrophy is a hallmark of several neurological and psychiatric conditions- including depression, PTSD, Alzheimers disease, and aging- understanding the mechanisms by which exercise increases neurogenesis has broad therapeutic relevance. One potential mechanism involves extracellular vesicles (EVs), lipid bilayer-enclosed particles released by multiple tissues during exercise that transport bioactive molecular cargo to distant organs, including the brain. In this study, we tested whether plasma-derived EVs from exercising mice (ExerVs) are sufficient to promote hippocampal neurogenesis, astrogliogenesis, and vascular density in sedentary mice. EVs were isolated from the plasma of sedentary or exercising C57BL/6J mice and injected intraperitoneally into sedentary recipients twice weekly for four weeks. To evaluate reproducibility, the study was conducted across two independent cohorts using identical procedures. ExerV-treated mice showed a significant increase in BrdU-positive cells in the granule cell layer compared to both PBS- and SedV-treated controls in both cohorts. Approximately 90% of these cells co-expressed NeuN, indicating neuronal differentiation, while 6% co-expressed S100B;, indicating astrocyte generation. No changes were observed in vascular density across groups. These findings provide initial evidence that systemically delivered exercise-derived EVs can enhance hippocampal neurogenesis and astrogliogenesis in sedentary mice. This proof-of-concept work supports further investigation into ExerVs as a potential therapeutic strategy for conditions associated with hippocampal atrophy.