Biotherapies in multiple sclerosis: a step toward remyelination and neuroprotection?

M2 Microglia-Derived Exosomal miR-144-5p Attenuates White Matter Injury in Preterm Infants by Regulating the PTEN/AKT Pathway Through KLF12

Perinatal white matter injury (WMI), which is prevalent in premature infants, involves M2 microglia affecting oligodendrocyte precursor cells (OPCs) through exosomes, promoting OPC growth and reducing WMI. The molecular mechanism of WMI remains unclear, and this study explored the role of M2 microglia-derived exosomes in WMI. A tMCAO rat model was constructed to simulate WMI characteristics in vivo. Cresyl violet staining, neurobehavioral tests, rotarod tests, immunofluorescence and immunochemistry were used to assess the role of exos-derived miR-144-5p in pathological and neurological changes in rats. OGD/R cellular models were constructed to mimic WMI characteristics in vitro. CCK-8, TUNEL, Western blotting and immunofluorescence were used to assess the role of exos-derived miR-144-5p in OPC phenotypes. Rescue assays were used to assess the role of the PTEN/AKT pathway in miR-144-5p-mediated OPC phenotypes. Bioinformatics and mechanistic experiments were used to assess the association of PTEN or KLF12 with miR-144-5p in OPCs. M2-Exos suppressed cerebral injury and facilitated demyelination repair in rats post WMI. M2-Exos suppressed OGD/R-stimulated OPC apoptosis and facilitated OGD/R-stimulated OPC differentiation. M2-Exo-derived miR-144-5p suppressed OGD/R-stimulated OPC apoptosis and facilitated OGD/R-stimulated OPC differentiation. M2-Exo-derived miR-144-5p suppressed cerebral injury and facilitated demyelination repair in rats post WMI. MiR-144-5p suppressed OGD/R-stimulated OPC apoptosis and facilitated OGD/R-stimulated OPC differentiation through PTEN downregulation. MiR-144-5p targeted the KLF12 3'UTR to repress PTEN transcription in OPCs. M2 microglia secrete miR-144-5p to reduce WMI by targeting KLF12 in OPCs, inhibiting PTEN/AKT pathway activity, and offering potential targeted therapeutic insights for WMI.

Whole-brain ex-vivo quantitative MRI of the cuprizone mouse model

Myelin is a critical component of the nervous system and a major contributor to contrast in Magnetic Resonance (MR) images. However, the precise contribution of myelination to multiple MR modalities is still under debate. The cuprizone mouse is a well-established model of demyelination that has been used in several MR studies, but these have often imaged only a single slice and analysed a small region of interest in the corpus callosum. We imaged and analyzed the whole brain of the cuprizone mouse ex-vivo using high-resolution quantitative MR methods (multi-component relaxometry, Diffusion Tensor Imaging (DTI) and morphometry) and found changes in multiple regions, including the corpus callosum, cerebellum, thalamus and hippocampus. The presence of inflammation, confirmed with histology, presents difficulties in isolating the sensitivity and specificity of these MR methods to demyelination using this model.