Angiogenesis in the regenerating tail of the leopard gecko, Eublepharis macularius

Abstract

Angiogenesis has well documented roles in embryonic development and tumourigenesis, and is also involved in the phenomenon of tissue repair and regeneration. We investigated angiogenesis during complex multi-tissue regeneration using the leopard gecko tail as a novel model. Similar to many lizards, leopard geckos are able to naturally regenerate their tails following predation. Using various mammalian angiogenic markers (alpha-smooth muscle actin (α-SMA), vascular endothelial growth factor (VEGF), thrombospondin-1 (TSP-1), and cluster of differentiation 36 (CD36)) we characterized angiogenesis during reparative regeneration. After an initial wound healing phase, tail regeneration begins with the formation of an aggregation of proliferating cells (blastema). As the blastema increases in size new capillaries develop, lined by VEGF positive endothelial cells (ECs). Continued maturation of vessels corresponds with the recruitment of α-SMA positive pericytes, as well as ongoing VEGF expression in ECs. While TSP-1 is not expressed in ECs, it is seen transiently in cells of the blastema immediately following wound healing. CD36 is expressed in ECs of the late stage regenerate tail, presumably involved in TSP-1 mediated vessel remodelling. We demonstrate that regenerative angiogenesis forms an organized vascular network through a highly regulated process comparable to embryonic embryogenesis. Grant Funding Source: NSERC, CIHR