A human-induced pluripotent stem cell-derived spheroid model to investigate myelin injury and repair

Key Points:

• Researchers engineered iPSC-derived CNS spheroids enriched with mature myelinating oligodendrocytes and functional microglia by seeding separately differentiated iPSC-derived macrophage-like precursor cells, which matured into microglia within the spheroids, mimicking early CNS development.
• LPC treatment induced significant myelin fragmentation and demyelination in spheroids without causing overt microglial activation; microglia responded by phagocytosing myelin debris, confirmed via colocalization studies and electron microscopy.
• Single-cell RNA sequencing 24 hours post-LPC revealed gene expression changes in oligodendrocytes, OPCs, and microglia that closely mirror those observed in human MS lesions, validating the spheroid model's relevance for studying MS pathology.
• Following LPC-induced demyelination, OPCs proliferated and differentiated into new myelinating oligodendrocytes, forming compact myelin sheaths over weeks, as demonstrated by EdU incorporation, immunostaining, and electron microscopy.
• Treatment with the remyelinating drug clemastine fumarate after LPC exposure significantly enhanced the generation of new myelinating oligodendrocytes in spheroids, highlighting the model's utility for therapeutic screening.