Laser-targeted ablation of the zebrafish embryonic ventricle: A novel model of cardiac injury and repair
Matrone G, Taylor JM, Wilson KS, Baily J, Love GD, Girkin JM, Mullins JJ, Tucker CS, Denvir MA. Laser-targeted ablation of the zebrafish embryonic ventricle: A novel model of cardiac injury and repair. Int J Cardiol. 2013 Jul 17. doi:pii: S0167-5273(13)01117-0. 10.1016/j.ijcard.2013.06.063. [Epub ahead of print] PubMed PMID: 23871347. READ FULL ARTICLE
While the adult zebrafish (Danio rerio) heart demonstrates a remarkable capacity for self-renewal following apical resection little is known about the response to injury in the embryonic heart.
Injury to the beating zebrafish embryo heart was induced by laser using a transgenic zebrafish expressing cardiomyocyte specific green fluorescent protein. Changes in ejection fraction (EF), heart rate (HR), and caudal vein blood flow (CVBF) assessed by video capture techniques were assessed at 2, 24 and 48 h post-laser. Change in total and mitotic ventricular cardiomyocyte number following laser injury was also assessed by counting respectively DAPI (VCt) and Phospho-histone H3 (VCm) positive nuclei in isolated hearts using confocal microscopy.
Laser injury to the ventricle resulted in bradycardia and mild bleeding into the pericardium. At 2 h post-laser injury, there was a significant reduction in cardiac performance in lasered-hearts compared with controls (HR 117 ± 11 vs 167 ± 9 bpm, p ≤ 0.001; EF 14.1 ± 1.8 vs 20.1 ± 1.3%, p ≤ 0.001; CVBF 103 ± 15 vs 316 ± 13μms− 1, p ≤ 0.001, respectively). Isolated hearts showed a significant reduction in VCt at 2 h post-laser compared to controls (195 ± 15 vs 238 ± 15, p ≤ 0.05). Histology showed necrosis and apoptosis (TUNEL assay) at the site of laser injury. At 24 h post-laser cardiac performance and VCt had recovered fully to control levels. Pretreatment with the cell-cycle inhibitor, aphidicolin, significantly inhibited functional recovery of the ventricle accompanied by a significant inhibition of cardiomyocyte proliferation.
Laser-targeted injury of the zebrafish embryonic heart is a novel and reproducible model of cardiac injury and repair suitable for pharmacological and molecular studies.
MOVIE 1: Laser pulse injury (without synchronisation) of the zebrafish embryonic heart ventricle at 72 h post-fertilization– A single laser pulse, using the XYClone Laser Ablator, to the ventricle of a zebrafish embryo (72 hpf) results in instantaneous cardiac injury associated with marked bradycardia and gradual recovery of cardiac rhythm over the next few minutes. A laser burn-mark is clearly seen in the wall of the ventricle. This is an example where there is a clear view of non-overlapped cardiac chambers.