Fig. 6

Fgfr Inhibition Blocks Epicardial EMT, Disrupting Coronary Neovascularization and Arresting Regeneration (A) cmlc2 expression at 7, 14, and 30 dpa in heat-induced wild-type and hsp70:dn-fgfr1 zebrafish. Transgenic animals arrested regeneration of cmlc2-positive differentiated muscle around 14 dpa, leaving a large wound by 30 dpa. (B) Thirty dpa hearts stained with acid fuchsin-orange G (AFOG). Wild-type ventricles display small deposits of scar tissue (blue) within a restored myocardial wall, while hsp70:dn-fgfr1 hearts retain large amounts of fibrin (orange) and collagen (blue). (C) Wild-type and hsp70:dn-fgfr1 ventricles at 14 and 30 dpa, stained for tbx18 expression by ISH. Wild-type tbx18-positive cells integrate into the regenerating muscle, but hsp70:dn-fgfr1 tbx18-positive cells fail to integrate and accumulate at the apical edge of the wound. Clot material is outlined in red. (D) Wild-type fli1:EGFP and hsp70:dn-fgfr1; fli1:EGFP ventricles at 14 and 30 dpa. Wild-type regenerates are well vascularized (region within arrowheads). By contrast, transgenic wounds developed little or no organized endothelial structures in the vicinity of muscle. Occasionally, vessels were seen on the periphery of the wound, as indicated by arrowheads in these ventricles. hsp70:dn-fgfr1 ventricles also display heat-induced fluorescence from the EGFP-tagged transgene. Scale bar = 100 μm.