87 Neutrophil dynamics following acute myocardial injury live in an embryonic zebrafish model

Innate immune cells, particularly neutrophils, are the first responders following myocardial infarction (MI). During inflammation resolution, neutrophils undergo apoptosis contributing to a more reparative phenotype within the surrounding milieu. However, the function of neutrophils following MI is not well-defined. We hypothesise that inducing neutrophil apoptosis to resolve inflammation will enhance heart repair and regeneration following injury. We have developed a novel and reproducible model of acute cardiac injury by lasering the ventricle of embryonic zebrafish at 3 days post-fertilisation. Cardiomyocyte and neutrophil reporting zebrafish (Tg(myl7:GFP; mpx:mCherry)) were used to quantify the extent of heart injury, heart function and neutrophil dynamics live in vivo up to 48 hours post injury (hpi) by serial imaging using epifluorescent microscopy. Additionally, more sophisticated single plane illumination microscopy (SPIM) combined with optical gating technology is being used to image heart-neutrophil interactions at greater spatial and temporal resolution. Lasered embryos exhibit a loss of GFP at the ventricular apex. Percentage ventricular GFP lost increases and is most significant at 6hpi 3.75±0.635 compared to uninjured embryos (p