A Novel Zebrafish Larvae Hypoxia/Reoxygenation Model for Assessing Myocardial Ischemia/Reperfusion Injury

Strategies to reduce reperfusion injury after ischemia have been considered in clinical practice, but few interventions have successfully passed the proof-of-concept stage. In this study, we developed a novel zebrafish larvae hypoxia/reoxygenation (H/R) model to simulate myocardial ischemia/reperfusion injury (MIRI), with potential utility as a drug screening tool. After H/R treatment, videos of transgenic [Tg(cmlc:EGFP)] larval zebrafish hearts were captured using a digital high-speed camera, and the heart rate, diastolic area, systolic area, and total fraction of area changed were quantified. The mRNA expression of tnnt2, bnp, and hif1α was quantified, and red blood cells (RBCs) were detected by O-dianisidine staining. We found that a decline in cardiac contractility occurred in zebrafish larvae 48 h after hypoxia treatment. Reoxygenation for 2-5 h after 48 h of hypoxia caused heart dysfunction in zebrafish larvae, and were determined to be the optimum conditions for simulating MIRI similar to mammalian models. Our results indicated that heart dysfunction after reoxygenation in zebrafish larvae was accompanied by an upregulated gene expression of a number of myocardial injury biomarkers and increased numbers of RBCs. In conclusion, the novel larval zebrafish H/R model developed in this study could be used for rapid in vivo screening and efficacy assessment of MIRI therapeutics.