Traumatic brain injury (TBI) is a major global cause of long-term disability, with mild-to-moderate cases often leading to persistent neurological deficits. Current pharmacological interventions are limited by the blood-brain barrier and systemic side effects.

This study aims to investigate the therapeutic potential of exosomes (Exos) derived from tumor necrosis factor ɑ (TNFα) preconditioned fibroblast-like mesenchymal stem cells (FMSCs) for moderate TBI and compare their efficacy with untreated exosomes.

A mouse TBI model was established by closed-capsule blast shock wave injury. A total of 68 male mice were randomly divided into four groups (17 mice in each group): Sham group, TBI group, TBI+Exos group and TBI+TNFα-Exos group. Frontal bone-derived FMSCs were preconditioned with TNFα for 48 h. Exos were isolated and purified using the OMEGA kit. Mice in the TBI, TBI+Exos and TBI+TNFα-Exos groups were subjected to TBI modeling, and intranasal administration was performed 1 h after modeling. Y-maze alternation test and nesting test were used to evaluate the recovery of behavioral function after Exos intervention. PKH67 fluorescence labeling was applied to observe the in vitro cellular uptake and intracerebral distribution of Exos. An inflammatory model of mouse microglial BV2 cells was induced by lipopolysaccharide (LPS), and cells were divided into Control group, LPS group, Exos group and TNFα-Exos group. qRT-PCR was adopted to detect the expression levels of pro-inflammatory factors TNFα, interleukin-1β (IL-1β) and interleukin-6 (IL-6) in vitro.

Behavioral tests showed that the spontaneous alternation rate of the Y-maze was markedly increased in the Exos and TNFɑ-Exos groups compared to the TBI model group (P＜0.05). Nesting ability was significantly reduced in the TBI group compared with the Sham group, while notable improvements were observed in the Exos and TNFɑ-Exos groups (P＜0.05). qRT-PCR results demonstrated that the expression levels of pro-inflammatory factors in microglia were significantly decreased in the Exos and TNFɑ-Exos groups compared with the LPS group (P＜0.05). Furthermore, the TNFα-Exos group showed better improvements in the above indicators than the Exos group, and the difference was statistically significant (P＜0.05).

TNFα-preconditioned MSC-derived Exos exhibit favorable neuroprotective potential for early intervention in mild-to-moderate traumatic brain injury. Compared with conventional Exos, TNFα-Exos show superior effects in downregulating pro-inflammatory factors and improving cognitive function, which provides experimental evidence for the early treatment of military blast-induced brain injury.