Immunomodulatory and neuroprotective effects of miR-146a-enriched MSC-derived extracellular vesicles in experimental
Fatemeh Shahryari1, Morteza Jafarinia2, Mojtaba Jafarinia3
1Department of Biology, Marv.C., Islamic Azad University, Marvdasht, Iran.
Background:
Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as promising cell-free therapeutics due to their immunomodulatory and reparative properties, especially through microRNAs (miRNAs). This study investigates the therapeutic potential of EVs enriched with miR-146a-EVs, a key regulator of inflammatory signaling, in experimental autoimmune encephalomyelitis (EAE), a murine model of MS.
Methods:
Human adipose-derived MSCs (hADSCs) were transfected with miR-146a mimics or miR-control, and their EVs were isolated. After EAE induction in C57BL/6 mice, they were treated intravenously with miR-146a-enriched EVs, control EVs, or PBS. Clinical scores were monitored for 30 days. Cytokine levels (tumor necrosis factor (TNF)-α, interferon-gamma (IFN-γ), interleukin (IL)-17, IL-4, IL-10, transforming growth factor beta (TGF-β)) were measured in splenocytes and spinal cord tissue using enzyme-linked immunosorbent assay (ELISA) and quantitative polymerase chain reaction (qPCR), respectively. Histopathology (Hematoxylin and Eosin (H&E), Luxol Fast Blue (LFB)) and immunohistochemistry (Myelin Basic Protein (MBP)) assessed inflammation and demyelination.
Results:
miR-146a-enriched EVs significantly attenuated EAE severity, reducing pro-inflammatory cytokines (TNF-α, IFN-γ, IL-17) and elevating anti-inflammatory cytokines (IL-10, TGF-β) in both splenocyte cultures and spinal cord tissue. The miR-146a-EV-treated group also showed a significant downregulation in Interleukin-1 Receptor-Associated Kinase 1 (IRAK1) and Tumor Necrosis Factor Receptor-Associated Factor 6 (TRAF6) mRNA levels. Histopathological analysis revealed diminished neuroinflammation and demyelination, alongside enhanced myelin preservation in miR-146a-enriched EVs-treated mice.
Conclusion:
These findings demonstrate that miR-146a-enriched EVs effectively modulate immune responses, suppress neuroinflammation, and promote neuroprotection in EAE, highlighting their potential as a novel therapeutic strategy for MS. By targeting both inflammatory and degenerative pathways, miR-146a-enriched EVs represent a multifaceted approach to address the unmet needs in MS treatment.
