Early Single-Dose Treatment with Exosomes Provides Neuroprotection and Improves Blood-Brain Barrier Integrity in Swine Model of Traumatic Brain Injury and Hemorrhagic Shock

BACKGROUND: Administration of human mesenchymal stem cell (MSC)-derived exosomes can enhance neurorestoration in models of traumatic brain injury (TBI) and hemorrhagic shock (HS). The impact of early treatment with MSC-derived exosomes on brain injury in a large animal model remains unknown. We sought to evaluate the impact of early single-dose exosome treatment on brain swelling and lesion size, blood-based cerebral biomarkers, and blood-brain barrier (BBB) integrity. METHODS: Female Yorkshire swine were subjected to a severe TBI (12-mm cortical impact) and HS (40% estimated total blood volume). One hour into shock, animals were randomized (n=5/cohort) to receive either lactated Ringer\u27s (LR; 5mL) or LR + exosomes (LR+EXO; 1 x 10 exosome particles in 5 mL LR). Animals then underwent additional shock (1 hr) followed by normal saline resuscitation. After 6 hours of observation, brain swelling (% increase compared to the uninjured side) and lesion size (mm) were assessed. Cerebral hemodynamics and blood-based biomarkers of brain injury were compared. Immunofluorescence and RNA sequencing with differential gene expression and pathway analysis were used to assess the integrity of the peri-lesion BBB. RESULTS: Exosome-treated animals had significantly less (p \u3c 0.05) brain swelling and smaller lesion size. They also had significantly decreased (p \u3c 0.05) intracranial pressures and increased cerebral perfusion pressures. Exosome-treated animals had significantly decreased (p \u3c 0.05) albumin extravasation and significantly higher (p \u3c 0.05) laminin, claudin-5, and zonula occludens-1 levels. Differential gene expression and pathway analysis confirmed these findings. Serum glial fibrillary acidic protein levels were also significantly lower (p\u3c0.05) in the exosome-treated cohort at the end of the experiment. CONCLUSIONS: In a large animal model of TBI and HS, early treatment with a single dose of MSC-derived exosomes significantly attenuates brain swelling and lesion size, decreases levels of blood-based cerebral biomarkers, and improves BBB integrity. LEVEL OF EVIDENCE: Not applicable (pre-clinical study)