Bone marrow-derived mesenchymal stem cells overexpressed with miR-182-5p protects against brain injury in a mouse model of cerebral ischemia.

Background: Toll-like receptor 4 (TLR4) plays a critical role in ischemic brain injury by mediating the inflammatory response. The microRNA miR-185-5p suppresses inflammatory signaling by targeting TLR4. This study investigates whether overexpressing miR-182-5p in bone marrow-derived mesenchymal stem cells (BM-MSCs) could potentiate the neuroprotective effects of BM-MSCs in a mouse model of ischemic brain injury.

Methods: We isolated BM-MSCs from mice, transfected the cells with miR-182-5p mimic, determined their MSC lineage through flow cytometry analysis of surface markers, examined miR-182-5p and TLR4 expression levels, and injected them into mice undergone middle cerebral artery occlusion (MCAO). MSC transplanted mice were subjected to behavior assays to determine cognitive and motor functions and biochemical analysis to determine neuroinflammation and TLR4/NF-κB in the ischemic hemisphere.

Results: We found that BM-MSCs overexpressing miR-182-5p showed reduced TLR4 expression without affecting their MSC lineage. Mice transplanted with miR-182-5p overexpressing BM-MSCs after MCAO showed significantly improved cognitive and motor functions and reduced neuroinflammation, including suppressed microglial M1 polarization, reduced inflammatory cytokines, and inhibited TLR4/ NF-κB signaling.

Conclusion: Our findings suggest that overexpressing miR-182-5p in BM-MSCs can enhance the neuroprotective effects of BM-MSCs against ischemic brain injury by suppressing TLR4-mediated inflammatory response.