Radial glial progenitors repair the zebrafish spinal cord following transection

• A dbx1a:GFP reporter transgene labels radial glial progenitors beyond embryogenesis.
• Zebrafish larvae rapidly regenerate lost neurons and regain sensory and motor function after complete spinal transection.
• dbx1a:GFP+ cells proliferate and undergo neurogenesis after spinal cord transection.

In mammals, spinal cord injury results in permanent sensory–motor loss due in part to a failure in reinitiating local neurogenesis. However, zebrafish show robust neuronal regeneration and functional recovery even after complete spinal cord transection. Postembryonic neurogenesis is dependent upon resident multipotent progenitors, which have been identified in multiple vertebrates. One candidate cell population for injury repair expresses Dbx1, which has been shown to label multipotent progenitors in mammals. In this study, we use specific markers to show that cells expressing a dbx1a:GFP reporter in the zebrafish spinal cord are radial glial progenitors that continue to generate neurons after embryogenesis. We also use a novel larval spinal cord transection assay to show that dbx1a:GFP+ cells exhibit a proliferative and neurogenic response to injury, and contribute newly-born neurons to the regenerative blastema. Together, our data indicate that dbx1a:GFP+ radial glia may be stem cells for the regeneration of interneurons following spinal cord injury in zebrafish.