Adult rat myelin enhances axonal outgrowth from neural stem cells

Sci Transl Med. 2018 May 23;10(442):eaal2563. doi: 10.1126/scitranslmed.aal2563.


Axon regeneration after spinal cord injury (SCI) is attenuated by growth inhibitory molecules associated with myelin. We report that rat myelin stimulated the growth of axons emerging from rat neural progenitor cells (NPCs) transplanted into sites of SCI in adult rat recipients. When plated on a myelin substrate, neurite outgrowth from rat NPCs and from human induced pluripotent stem cell (iPSC)-derived neural stem cells (NSCs) was enhanced threefold. In vivo, rat NPCs and human iPSC-derived NSCs extended greater numbers of axons through adult central nervous system white matter than through gray matter and preferentially associated with rat host myelin. Mechanistic investigations excluded Nogo receptor signaling as a mediator of stem cell-derived axon growth in response to myelin. Transcriptomic screens of rodent NPCs identified the cell adhesion molecule neuronal growth regulator 1 (Negr1) as one mediator of permissive axon-myelin interactions. The stimulatory effect of myelin-associated proteins on rodent NPCs was developmentally regulated and involved direct activation of the extracellular signal-regulated kinase (ERK). The stimulatory effects of myelin on NPC/NSC axon outgrowth should be investigated further and could potentially be exploited for neural repair after SCI.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / metabolism*
  • Animals
  • Axons / metabolism*
  • Axons / ultrastructure
  • Cell Adhesion Molecules, Neuronal / genetics
  • Cell Adhesion Molecules, Neuronal / metabolism
  • Chondroitin Sulfate Proteoglycans / metabolism
  • Cyclic AMP / metabolism
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Female
  • Gray Matter / cytology
  • Humans
  • Mice, Inbred C57BL
  • Myelin Sheath / metabolism*
  • Myelin Sheath / ultrastructure
  • Neural Stem Cells / cytology*
  • Neural Stem Cells / ultrastructure
  • Neuronal Outgrowth*
  • Phosphorylation
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats, Inbred F344
  • Rats, Nude
  • Spinal Cord / cytology
  • White Matter / cytology


  • Cell Adhesion Molecules, Neuronal
  • Chondroitin Sulfate Proteoglycans
  • NEGR1 protein, mouse
  • RNA, Messenger
  • Cyclic AMP
  • Extracellular Signal-Regulated MAP Kinases