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Advanced Neurology Cytokine response to EV therapy in SCI

alongside a more moderate rise in the anti-inflammatory signaling pathways, such as reducing fibrinogen interaction
cytokine IL-10. Cytokines such as GM-CSF, IFN-γ, with αVβ3 receptors or regulating CD11b/CD18-mediated
and IL-6 were particularly elevated, possibly reflecting microglial activation. EV cargo, including regulatory
the intrinsic hemostatic properties of FM. Notably, miRNAs or surface molecules, could contribute to these
IL-6—increased 2.4-fold in the FM group—was partially modulatory effects, potentially influencing natural tissue
normalized in both EV-treated groups, particularly in repair processes following traumatic injuries. It is also
FM+EVs10, indicating that EVs counteracted FM-induced important to note that differences in viral inactivation and
upregulation of inflammatory cytokines. This supports the processing methods between Tisseel and Vistaseal have
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role of MSC-EVs in fine-tuning the local cytokine milieu, been suggested to theoretically influence the inflammatory
underscoring their capacity to modulate complex immune potential of Tisseel . However, the clinical significance of
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responses in the chronic phase of SCI. Previous studies these differences has not yet been fully established. 23
indicate that fibrin glues, such as Tisseel (also referred Our study is among the first to explore the effects of
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to as Tissucol in our study), despite their hemostatic
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properties, can elicit local inflammatory responses. 17,18 In FM combined with MSC-EVs on the cytokine profile
one study, fibrin glue application in a rat SCI model did not during the chronic phase of SCI (60 dpi). While previous
reduce inflammation, an effect likely linked to activation research has examined the role of MSC-EVs encapsulated
of coagulation-dependent inflammatory cascades. This in FM in promoting oligodendrogenesis and functional
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may explain the elevated levels of pro-inflammatory recovery, as well as neurogenesis in rodent models
cytokines observed in our experiment. In addition, a study of chronic SCI, the impact of this combination on
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comparing Tisseel with other adhesives, such as BioGlue neuroinflammatory processes within the injured spinal
and Adherus , demonstrated that Tisseel caused relatively cord has not been addressed. We found that MSC-EVs can
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less pronounced inflammatory and degenerative responses mitigate cytokine shifts at the injury site induced by local
in rat SCI. However, even in these cases, localized FM exposure, exhibiting a clear dose-dependent effect.
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inflammatory reactions were still observed, aligning with Specifically, increasing the MSC-EV dosage significantly
our findings. It is noteworthy that these studies examined reduced the expression levels of IL-1β, IL-5, IL-17A,
the effects of adhesives on inflammation up to 28 days and IL-10 compared to the FM-only group. However,
post-application, whereas our study extended to 60 dpi, the notably elevated RANTES (CCL5) levels observed in
suggesting that FM-induced inflammatory responses can the SCI FM+EVs5 group, as opposed to the FM+EVs10
persist into the chronic stage of SC. group, warrant further investigation to clarify its role in
anti-inflammatory or regenerative processes. This increase
The study of FM biodegradation in the body is also may reflect an insufficient dose of EVs to fully suppress
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noteworthy. As a biocompatible material, Tisseel is specific pro-inflammatory pathways or could represent
slowly resorbed in tissues, which may lead to prolonged a transitional state in immune modulation. Given the
interactions with surrounding cells and potentially pleiotropic functions of RANTES in both promoting and
sustain an inflammatory response. Research on various resolving inflammation depending on context, its dose-
commercial fibrin matrices, including Tisseel , has shown dependent dynamics in response to EV therapy are of
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that the presence of protease inhibitors like aprotinin slows particular interest for future studies.
its biodegradation, suggesting that its extended presence in
tissues may have prolonged effects on cellular responses. A key point of comparison with our previous results is the
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In an in vitro study, Tisseel was also found to increase dose-dependent immunomodulatory effect of MSC-EVs.
metalloproteinases (MMP-1, MMP-2) levels in mesothelial The application of 10 µg MSC-EVs (SCI FM+EVs10) led to
cells and fibroblasts, which may alter cytokine profiles a significant reduction in both pro-inflammatory cytokines
and prolong inflammation during matrix degradation. (IL-1β, IL-5, IL-17A) and the anti-inflammatory cytokine
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Furthermore, studies have identified key cellular targets IL-10. This is consistent with our prior study, where
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and molecular mechanisms by which fibrinogen and higher EV doses resulted in greater tissue preservation and
thrombin, essential components of Tisseel , can hinder enhanced electrophysiological recovery (M-wave, MEP,
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neurotrauma recovery. For instance, fibrinogen binding and SSEP measurements), indicating that MSC-EVs do not
to αVβ3 inhibits neurite outgrowth in the central nervous merely suppress inflammation but instead regulate it toward
system (CNS), as demonstrated in a mouse model of a balanced immune state. The reduction in IL-10, therefore,
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encephalomyelitis, while its interaction with CD11b/ does not necessarily indicate heightened inflammation but
CD18 activates microglia in a mouse model of traumatic rather suggests a dampened immune activation requiring
brain injury. It is plausible that MSC-EVs may attenuate less compensatory regulation, reflecting a reestablishment
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FM-associated inhibitory signals by modulating integrin of immune balance. Another strong correlation with our

Volume 4 Issue 4 (2025) 82 doi: 10.36922/AN025110022