Abstract 123: Establishing a Zebrafish Model of Ischemic Stroke Induced by Photochemical Thrombosis: a Novel Platform for Translational Researches

Introduction: Ischemic stroke is a leading cause of death and disability worldwide. Animal models of stroke are important for translational researches. We herein developed a novel zebrafish model of ischemic stroke using selective photochemical thrombosis, based on which further pathophysiological studies and pharmacological screening can be done. Method: Using 5 day post-fertilization zebrafish larva, we injected a photosensitizer rose bengal (120 pg) into the cardinal vein and employed a green laser (λ = 532 nm) targeting at selected cerebral arteries to induce photochemical thrombosis. The fluorescent FITC-dextran was used to stain the larval blood. The dynamic cerebral blood flow was continuously monitored. The neuronal death 12 h after arterial occlusion was indicated by acridine orange (AO). A neurological scoring system measuring the movement, coordination, and response to stimuli was established to determine the neurological function at 24 h. Thrombolysis using recombinant tissue plasminogen activator (rt-PA, 300 ng) at 0.5 and 3 h post-occlusion with comparison of the above parameters was used to demonstrate the potential application of this model. Results: Photochemical thrombosis consistently induced occlusion of the selected cerebral arteries. Occlusion at the basilar artery led to high mortality (73.3% at 12 h). All zebrafish survived the occlusion at the 1 st branch of central artery (CtA), but showed significantly increased AO stain and worsened neurological scores than control. Early treatment of rt-PA at 0.5 h post-occlusion resulted in a higher re-canalization rate than that at 3 h (40.0 vs. 26.7%). Moreover, the early treatment group exhibited significantly lower AO stain (42.2 ± 9.4 vs. 102.6 ± 17.4 a.u., P < 0.05) and improved neurological scores (4.2 ± 0.8 vs. 2.7 ± 1.1, P < 0.05). In contrast, no significant improvement was shown in the delayed treatment group even if the occluded artery had been reopened. Conclusion: This zebrafish model of ischemic stroke demonstrates characteristic pathophysiological responses and therapeutic effects seen in clinical stroke. With zebrafish being an increasingly employed model animal, there exist great potentials for this model to be applied in basic researches and translational studies.