Establishment and validation of an in vitro co-culture model to study myelination using human iPSC-derived glutamatergic neurons and oligodendrocytes

Oligodendrocytes, the myelinating cells of the central nervous system (CNS), wrap their cell membrane around axons to support rapid nerve impulse conduction. They develop from bipotential oligodendrocyte-type-2-astrocyte progenitors (O2A), which can differentiate in vitro into either oligodendrocytes or astrocytes. Oligodendrocyte progenitor cells (OPC) react in human adult CNS to injury by proliferation and migration. Oligodendrocyte dysfunction and disrupted myelin is involved in the pathogenesis of neurodegenerative disease such as multiple sclerosis (MS) and Alzheimer’s disease (AD).

Although microglia and astrocytes have been extensively characterised in neurodegeneration, oligodendrocytes have received less attention due to the complexity of primary oligodendrocyte isolation and culturing. Induced pluripotent stem cells (iPSCs)-derived oligodendrocytes can provide a suitable solution to study differentiation and maturation of oligodendrocytes as well as myelination.

Charles River Laboratories has successfully established a relevant in vitro mono- and co-culture myelination model using iPSC-derived ioOligodendrocyte-like cells and ioGlutamatergic Neurons. Immunofluorescent staining of ioOligodendrocyte-like cells at different time points showed positive staining for key oligodendrocyte lineage markers including Olig2, O4, and SOX2 and myelin markers, including myelin-binding protein (MBP) and myelin proteolipid protein (PLP). At day 3 post seeding the O4+ cells displayed a typical OPC-like morphology. They mature into oligodendrocyte-like cells with characteristic multiple branched processes. Co-culture of ioGlutamatergic Neurons and ioOligodendrocyte-like cells resulted in increased number of MBP+ cells compared to monocultures of oligodendrocytes in a time-dependent manner. Importantly, high content imaging showed that MBP+ cells surrounded neurites in the co-culture, indicating myelination of neuronal axons.