Local cytokine changes following fibrin-encapsulated mesenchymal stem cell-derived extracellular vesicle therapy in rat spinal cord injury

Spinal cord injury (SCI) induces a prolonged and complex inflammatory response that contributes to secondary damage and influences functional recovery. Targeting this inflammatory milieu represents a promising therapeutic strategy. In this study, we investigated the effects of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) and encapsulated in a fibrin matrix (FM) on cytokine regulation in a rat model of SCI 60 days post-injury. MSCs were isolated from rat adipose tissue, and EVs were obtained using cytochalasin B-induced vesiculation. The EVs were encapsulated in FM and applied locally to the injury site at doses of 5 and 10 μg. The SCI rat models were divided into four groups: untreated, treated with FM alone, treated with 5 μg of EVs in FM (FM+EVs5), and treated with a 10 μg dose (FM+EVs10). A multiplex assay was employed to quantify the levels of 23 cytokines in spinal cord tissue homogenates. The application of FM alone altered cytokine levels, notably increasing granulocyte colony-stimulating factor (G-CSF) levels by 2.8-fold, which may be attributed to the hemostatic and bioactive properties of fibrin. Treatment with MSC-derived EVs resulted in a dose-dependent modulation of inflammatory responses. In the FM+EVs10 group, pro-inflammatory cytokines interleukin (IL)-1β and IL-5, as well as the anti-inflammatory cytokine IL-10, were significantly reduced compared to both the untreated and FM-alone groups, with IL-10 levels decreasing 2.4-fold. A similar trend was observed for IL-17A, which was 1.6-fold lower in the FM+EVs10 group compared to the FM-alone group. These findings suggest that fibrin-encapsulated MSC-derived EVs can modulate inflammation in chronic SCI and warrant further investigation as a therapeutic approach for neuroprotection and tissue repair.