Manot-Saillet, B. | bioRxiv Science

bioRxiv2022

Versatile and automated workflow for the analysis of oligodendroglial calcium signals in preclinical mouse models of myelin repair

Intracellular Ca2+ signals of oligodendroglia, the myelin-forming cells of the central nervous system, regulate vital cellular processes including myelination. However, studies on oligodendroglia Ca2+ signal dynamics are still scarce, especially during myelin repair, and there are no software solutions to properly analyze the unique Ca2+ signal characteristics in these cells. Here, we provide a comprehensive experimental and analytical workflow to acquire and analyze Ca2+ imaging data of oligodendroglia at the population and single-cell levels in preclinical mouse models of myelin repair. We report diverse ex vivo and in vivo experimental protocols to obtain reproducible Ca2+ imaging data from oligodendroglia in demyelinated lesions. Importantly, we provide an analytical pipeline containing two free, open source and cross-platform software programs, Occam and post-prOccam, that enable the fully automated analysis of one- and two-photon Ca2+ imaging datasets from oligodendroglia obtained by either ex vivo or in vivo Ca2+ imaging techniques. This versatile and accessible experimental and analytical framework, which revealed significant but uncorrelated spontaneous Ca2+ activity in oligodendroglia inside demyelinated lesions, should facilitate the elucidation of Ca2+-mediated mechanisms underlying remyelination and therefore help to accelerate the development of therapeutic strategies for the many myelin-related disorders, such as multiple sclerosis.

neuroscience↗

bioRxiv2020

Multiple sclerosis iPSC-derived oligodendroglia conserve their intrinsic properties to functionally interact with axons and glia in vivo

The remyelination failure in multiple sclerosis (MS) is associated with a migration/differentiation block of oligodendroglia. The reason for this block is highly debated. It could result from disease-related extrinsic regulators of the oligodendroglial biology or reflect MS oligodendrocyte intrinsic properties. To avoid confounding immune-mediated extrinsic effect, we used an immune-deficient, dysmyelinating mouse model, to compare side-by-side induced pluripotent stem-cell-derived O4+ oligodendroglia from MS and healthy donors following their engraftment in the developing CNS. We show that the MS-progeny survives, proliferates and differentiates into oligodendrocytes to the same extent as controls. Quantitative multi-parametric imaging indicates that MS and control oligodendrocytes generate equal amounts of myelin, with bona-fide nodes of Ranvier and promote equal restoration of their host slow conduction. Moreover, the MS-derived progeny expressed oligodendrocyte- and astrocyte-specific connexins and established functional connections with donor and host glial cells. Thus, MS pluripotent stem cell-derived progeny fully integrates into functional axo-glial and glial-glial components, reinforcing the view that the MS oligodendrocyte differentiation block is not due to intrinsic oligodendroglial deficits. These biological findings as well as the fully integrated human-murine chimeric model should facilitate the development of pharmacological or cell-based therapies to promote CNS remyelination. One Sentence SummaryMultiple Sclerosis oligodendroglia, regardless of major immune manipulators, are intrinsically capable of myelination and making functional axo-glia and glia-glia connections after engraftment in the murine CNS, reinforcing the view that the MS oligodendrocyte differentiation block is not due to major intrinsic oligodendroglial deficits but most likely to environmental conditions.

neuroscience↗