Adult neural precursor cells and the dysmyelinated spinal cord.

Editor's Note: These short reviews of a recent paper in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to mimic the journal clubs that exist in your own departments or institutions. For more information on the format and purpose of the Journal Club, please see Review of Eftekharpour et al. The myelin surrounding axons is highly organized, with ion channels and adaptor molecules densely clustered at nodes of Ranvier. Loss of myelin decreases impulse conduction and ultimately leads to degen-eration of axons. Demyelinated axons also have disrupted organization, with loss of K ϩ channels contributing to functional deficits (Karimi-Abdolrezaee et al., 2004). Cell-based treatments are one approach to repair the loss of myelin and damaged axons (Ben-Hur et al. A recent study in The Journal of Neuro-science (Eftekharpour et al., 2007) examined the role of adult neural precursor cells (aNPCs) in myelin repair (Fig. 1). As a model system, the authors used a congenitally myelin-deficient transgenic Shiverer (shi/shi) mouse with sparse mye-lin sheaths and altered nodal K ϩ channels. The adult NPCs had the ability to commit to the three main CNS cell types in ratios similar to that seen by previous studies. This demonstrated potential is routine and well established for adult NPCs but nonetheless important [Eftekharpour et al. The authors assumed that adult NPCs were multipotent; however, clonal sphere formation was not performed. Using light and electron mi-croscopy, the authors illustrate that shi/shi mice lacked myelin basic protein (MBP) and compact myelin [Eftekharpour et al. accompanied by a mitogen infusion including bFGF, EGF, and PDGF-AA, which improves the survival of transplanted cells and encourages development of oligodendrocytes (Karimi-Abdolrezaee et al., 2006). Adult NPCs survived, as represented by yellow fluorescent protein (YFP) staining, predominantly in the white matter, after transplantation into the young adult spinal cord or neonatal brain [Eftekharpour et al. (2007), their Fig. 2back of this transgenic mouse is the short life span (15 weeks) of the animal, making it difficult to assess long-term survival of the transplanted aNPCs. Using pheno-typic markers and confocal analysis, the authors predominantly observed oligo-dendrocyte cell commitment (78 Ϯ 9%) [Eftekharpour et al. Only 9 Ϯ 3% became GFAP-positive astrocytes, which is lower than previous transplantation studies. Although not discussed by the authors , the 7 d mitogen infusion might explain the low percentage of GFAPϩ cells. There was no evidence of neuronal or Schwann cell differentiation after …