A Novel Ex Vivo Model to Study Therapeutic Treatments for Myelin Repair following Ischemic Damage.

Stroke is a major reason for persistent disability due to insufficient treatment strategies beyond reperfusion, leading to oligodendrocyte death and axon demyelination, persistent inflammation and astrogliosis in peri-infarct areas. After injury, oligodendroglial precursor cells (OPCs) have been shown to compensate for myelin loss and prevent axonal loss through the replacement of lost oligodendrocytes, an inefficient process leaving axons chronically demyelinated. Phenotypic screening approaches in demyelinating paradigms revealed substances that promote myelin repair. We established an ex vivo adult organotypic coronal slice culture (OCSC) system to study repair after stroke in a resource-efficient way. Post-photothrombotic OCSCs can be manipulated for 8 d by exposure to pharmacologically active substances testing remyelination activity. OCSCs were isolated from a NG2-CreERT2-td-Tomato knock-in transgenic mouse line to analyze oligodendroglial fate/differentiation and kinetics. Parbendazole boosted differentiation of NG2+ cells and stabilized oligodendroglial fate reflected by altered expression of associated markers PDGFR-α, CC1, BCAS1 and Sox10 and GFAP. In vitro scratch assay and chemical ischemia confirmed the observed effects upon parbendazole treatment. Adult OCSCs represent a fast, reproducible, and quantifiable model to study OPC differentiation competence after stroke. Pharmacological stimulation by means of parbendazole promoted OPC differentiation.

Myelin repair is fostered by the corticosteroid medrysone specifically acting on astroglial subpopulations.

BACKGROUND: Multiple sclerosis is characterised by inflammation, oligodendrocyte loss and axonal demyelination and shows an additional impact on astrocytes, and their polarization. Although a certain degree of spontaneous myelin repair can be observed, disease progression, and aging impair regeneration efforts highlighting the need to better understand glial cell dynamics to establish specific regenerative treatments. METHODS: Applying a chronic demyelination model, we here analysed demyelination and remyelination related effects on astrocytes and stem cell niches and studied the consequences of medrysone application on myelin repair, and astrocyte polarization. FINDINGS: Medrysone induced recovery of mature oligodendrocytes, myelin expression and node formation. In addition, C3d/S100a10 co-expression in astrocytes was enhanced. Moreover, Timp1 expression in C3d positive astrocytes revealed another astrocytic phenotype with a myelination promoting character. INTERPRETATION: Based on these findings, specific astrocyte subpopulations are suggested to act in a myelin regenerative way and manner the regulation of which can be positively modulated by this corticosteroid. FUNDING: This work was supported by the Jürgen Manchot Stiftung, the Research Commission of the medical faculty of the Heinrich-Heine-University of Düsseldorf, the Christiane and Claudia Hempel Foundation for clinical stem cell research and the James and Elisabeth Cloppenburg, Peek and Cloppenburg Düsseldorf Stiftung.