A Subpopulation of Foxj1-Expressing, Nonmyelinating Schwann Cells of the Peripheral Nervous System Contribute to Schwann Cell Remyelination in the Central Nervous System.

Abstract

New myelin sheaths can be restored to demyelinated axons in a spontaneous regenerative process called remyelination. In general, new myelin sheaths are made by oligodendrocytes newly generated from a widespread population of adult CNS progenitors called oligodendrocyte progenitor cells (OPCs). New myelin in CNS remyelination in both experimental models and clinical disease can also be generated by Schwann cells, the myelin forming cells of the peripheral nervous system. Fate mapping studies have shown that Schwann cells contributing to remyelination in the CNS are often derived from OPCs, and appear not to be derived from myelinating Schwann cells from the PNS. In this study we address whether CNS remyelinating Schwann cells can also be generated from PNS derived cells other than myelinating Schwann cells. Using a genetic fate mapping approach, we have found that a sub-population of non-myelinating Schwann cells identified by the expression of the transcription factor foxj1 also contribute to CNS Schwann cell remyelination, as well as to remyelination in the peripheral nervous system. We also find the ependymal cells lining the central canal of the spinal cord, which also express foxj1, do not generate cells that contribute to CNS remyelination. These findings therefore identify a previously unrecognised population of PNS glia that can participate in the regeneration of new myelin sheaths following CNS demyelination.