title: Laser-targeted ablation of the zebrafish embryonic ventricle: a novel model of cardiac injury and repair.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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 ± 13 μms(-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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: University/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, EH16 4TJ, United Kingdom.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Matrone
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Taylor
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: Wilson
authors.forename: James
authors.initials: J
authors.lastname: Baily
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Love
authors.forename: John M
authors.initials: JM
authors.lastname: Girkin
authors.forename: John J
authors.initials: JJ
authors.lastname: Mullins
authors.forename: Carl S
authors.initials: CS
authors.lastname: Tucker
authors.forename: Martin A
authors.initials: MA
authors.lastname: Denvir
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles / Q000196:embryology* / Q000293:injuries* / Q000473:pathology; D053685:Laser Therapy / Q000009:adverse effects* / Q000379:methods; D023421:Models, Animal; D032383:Myocytes, Cardiac / Q000473:pathology; D013318:Stroke Volume / Q000502:physiology; D015027:Zebrafish
keywords: Heart; Injury; Laser; Repair; Zebrafish