Neural Stem/Progenitor Cells of the Spinal Cord are Activated in Response to Tail Loss in the Leopard Gecko

Abstract

As for many lizards, the leopard gecko (Eublepharis macularius) is able to self‐detach its tail as an anti‐predation strategy and subsequently regenerate a replacement. The replacement tail includes a regenerated spinal cord. We hypothesize that endogenous neural stem progenitor cells (NSPCs) are present in the original spinal cord and that these cells are activated during regeneration. As many stem cells are slow cycling, we used a Bromodeoxyuridine (BrdU) pulse‐chase experiment to identify label‐retaining populations in the original spinal cord. We also conducted a spatiotemporal characterization of spinal cord cells before and during regeneration using a panel of common NSPC markers (including Sox2, Sox9, Vimentin, βIII‐Tubulin and Musashi‐1, and the proliferation marker PCNA). BrdU retaining cells were still present after a 20‐week chase. Prior to injury, expression of NSPC markers is limited, but co‐localization of BrdU and Sox2 in ependymal cells was observed. Following tail loss, ependymal cells in the original stump of the tail become highly proliferative and express our panel of NSPC markers. Outgrowth of the new tail is matched by proliferating, NSPC marker‐positive ependymal cells. These cells appear to contribute to regenerating spinal cord. We conclude that ependymal cells are a likely source of endogenous NSPCs in the gecko and that they are activated following tail loss.NSERC Grant: 400358