reg6 is required for branching morphogenesis during blood vessel regeneration in zebrafish caudal fins

Abstract

Postnatal neovascularization is essential for wound healing, cancer progression, and many other physiological functions. However, its genetic mechanism is largely unknown. In this report, we study neovascularization in regenerating adult zebrafish fins using transgenic fish that express EGFP in blood vessel endothelial cells. We first describe the morphogenesis of regenerating vessels in wild-type animals and then the phenotypic analysis of a genetic mutation that disrupts blood vessel regeneration. In wild-type zebrafish caudal fins, amputated blood vessels heal their ends by 24 h postamputation (hpa) and then reconnect arteries and veins via anastomosis, to resume blood flow at wound sites by 48 hpa. The truncated vessels regenerate by first growing excess vessels to form unstructured plexuses, resembling the primary capillary plexuses formed during embryonic vasculogenesis. Interestingly, this mode of vessel growth switches by 8 days postamputation (dpa) to growth without a plexus intermediate. During blood vessel regeneration, vessel remodeling begins during early plexus formation and continues until the original vasculature pattern is reestablished at approximately 35 dpa. Temperature-sensitive mutants for reg6 have profound defects in blood vessel regeneration. At the restrictive temperature, reg6 regenerating blood vessels first fail to make reconnections between severed arteries and veins, and then form enlarged vascular sinuses rather than branched vascular plexuses. Reciprocal temperature-shift experiments show that reg6 function is required throughout plexus formation, but not during later growth. Our results suggest that the reg6 mutation causes defects in branch formation and/or angiogenic sprouting.

Regeneration of breeding tubercles on zebrafish pectoral fins requires androgens and two waves of revascularization

“…The overall fin vasculature in females is similar to that described in caudal fins (Huang et al, 2003). One artery runs down the center of each ray and two veins run along the external border of the rays.…”

Retinoic acid signaling spatially restricts osteoblasts and controls ray-interray organization during zebrafish fin regeneration

“…Blood vessels regenerate into the blastema accompanied by anastomosis between the injured arteries and veins of the same ray (Huang et al, 2003). Intriguingly, wounded arteries and veins had formed connections with vessels of neighboring rays in RA-and R115866-treated fli:gfp fish (Lawson and Weinstein, 2002) at 2.5 dpa ( Fig.…”

Animal Models of Angiogenesis and Lymphangiogenesis

“…One commonly used assay in the adult zebrafish, based on this principle is the regenerating tail fin. After amputation, the tail fin will re-grow and after approximately 1 month, the fin is back to its original size (Huang et al, 2003). This process of fin regeneration encompasses many of the same mechanisms as in human wound healing and regeneration, and is therefore a good model of regenerative angiogenesis.…”

“…Also in the fins, the vasculature is remarkably simple (Fig. 17), and as the fin grows back various levels of vascular remodeling can be observed and therefore studied in detail (Huang et al, 2003). This regeneration model is probably the most commonly used, adult zebrafish angiogenesis model, and is considered to be complementary to the developmental angiogenesis models.…”