Muscarinic receptor M ₃ R signaling prevents efficient remyelination by human and mouse oligodendrocyte progenitor cells

Muscarinic receptor antagonists act as potent inducers of oligodendrocyte differentiation and accelerate remyelination. However, the use of muscarinic antagonists in the clinic is limited by poor understanding of the operant receptor subtype, and questions regarding possible species differences between rodents and humans. Based on high selective expression in human oligodendrocyte progenitor cells (OPCs), we hypothesized that M ₃ R is the functionally relevant receptor. Lentiviral M ₃ R knockdown in human primary CD140a/PDGFαR ⁺ OPCs resulted in enhanced differentiation in vitro and substantially reduced the calcium response following muscarinic agonist treatment. Importantly, following transplantation in hypomyelinating shiverer/rag2 mice, M ₃ R knockdown improved remyelination by human OPCs. Furthermore, conditional M ₃ R ablation in adult NG2-expressing OPCs increased oligodendrocyte differentiation and led to improved spontaneous remyelination in mice. Together, we demonstrate that M ₃ R receptor mediates muscarinic signaling in human OPCs that act to delay differentiation and remyelination, suggesting that M ₃ receptors are viable targets for human demyelinating disease.