Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX 76205, USA.
SVP and head of Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg 431 50, Sweden.
Biol Open. 2024 Sep 15;13(9). doi: 10.1242/bio.060230. Epub 2024 Sep 12.
Contemporary cardiac injury models in zebrafish larvae include cryoinjury, laser ablation, pharmacological treatment and cardiac dysfunction mutations. Although effective in damaging cardiomyocytes, these models lack the important element of myocardial hypoxia, which induces critical molecular cascades within cardiac muscle. We have developed a novel, tractable, high throughput in vivo model of hypoxia-induced cardiac damage that can subsequently be used in screening cardioactive drugs and testing recovery therapies. Our potentially more realistic model for studying cardiac arrest and recovery involves larval zebrafish (Danio rerio) acutely exposed to severe hypoxia (PO2=5-7 mmHg). Such exposure induces loss of mobility quickly followed by cardiac arrest occurring within 120 min in 5 days post fertilization (dpf) and within 40 min at 10 dpf. Approximately 90% of 5 dpf larvae survive acute hypoxic exposure, but survival fell to 30% by 10 dpf. Upon return to air-saturated water, only a subset of larvae resumed heartbeat, occurring within 4 min (5 dpf) and 6-8 min (8-10 dpf). Heart rate, stroke volume and cardiac output in control larvae before hypoxic exposure were 188±5 bpm, 0.20±0.001 nL and 35.5±2.2 nL/min (n=35), respectively. After briefly falling to zero upon severe hypoxic exposure, heart rate returned to control values by 24 h of recovery. However, reflecting the severe cardiac damage induced by the hypoxic episode, stroke volume and cardiac output remained depressed by ∼50% from control values at 24 h of recovery, and full restoration of cardiac function ultimately required 72 h post-cardiac arrest. Immunohistological staining showed co-localization of Troponin C (identifying cardiomyocytes) and Capase-3 (identifying cellular apoptosis). As an alternative to models employing mechanical or pharmacological damage to the developing myocardium, the highly reproducible cardiac effects of acute hypoxia-induced cardiac arrest in the larval zebrafish represent an alternative, potentially more realistic model that mimics the cellular and molecular consequences of an infarction for studying cardiac tissue hypoxia injury and recovery of function.
当代斑马鱼幼虫的心脏损伤模型包括冷冻损伤、激光消融、药物处理和心脏功能障碍突变。虽然这些模型在损伤心肌细胞方面很有效，但它们缺乏心肌缺氧这一重要因素，而心肌缺氧会在心肌内引发关键的分子级联反应。我们开发了一种新颖的、易于处理的、高通量的体内缺氧诱导心脏损伤模型，可随后用于筛选心脏活性药物和测试恢复疗法。我们研究心脏骤停和恢复的潜在更现实的模型涉及急性暴露于严重缺氧（PO2=5-7mmHg）的斑马鱼幼虫（Danio rerio）。这种暴露会迅速导致运动能力丧失，随后在受精后 5 天内 120 分钟内发生心脏骤停，并在 10 天内 40 分钟内发生心脏骤停。大约 90%的 5 天龄幼虫能在急性缺氧暴露中存活，但到 10 天龄时存活率降至 30%。当回到空气饱和水中时，只有一部分幼虫恢复心跳，在 4 分钟（5 天龄）和 6-8 分钟（8-10 天龄）内发生。在缺氧暴露前，对照组幼虫的心率、每搏量和心输出量分别为 188±5bpm、0.20±0.001nL 和 35.5±2.2nL/min（n=35）。在严重缺氧暴露后短暂降至零后，心率在恢复 24 小时后恢复到对照值。然而，反映出严重的心脏损伤，由缺氧事件引起的每搏量和心输出量仍比恢复 24 小时时的对照值低约 50%，心脏功能的完全恢复最终需要心脏骤停后 72 小时。免疫组织化学染色显示肌钙蛋白 C（识别心肌细胞）和 Caspase-3（识别细胞凋亡）的共定位。作为对发育中的心肌采用机械或药物损伤的模型的替代，急性缺氧诱导的心脏骤停在斑马鱼幼虫中的高度重现的心脏效应代表了一种替代的、潜在更现实的模型，模拟了梗塞对研究心脏组织缺氧损伤和功能恢复的细胞和分子后果。
