建立斑馬魚全身缺氧再復氧之模型以模擬心搏停止及心肺復甦術─著眼於心搏停止後的心功能受損

Abstract

對公眾健康而言，心搏停止 (cardiac arrest) 是一個重要的議題，有接近百分之五十的心血管疾病死亡是由心臟驟停造成的。就算我們利用即時的心肺復甦術恢復心搏停止患者的自主血液循環 (return of spontaneous circulation, ROSC)，有只有百分之五到十的人可以存活下來。如此低的存活率主要是由所謂「後心搏停止綜合症 (cardiac arrest syndrome)」造成的。後心搏停止綜合症是在心搏停止的過程中造成的全身缺血和恢復自主血液循環之後產生的再灌流反應所引發一系列複雜的病理生理過程。許多傳統的動物模型如：大鼠、小鼠、豬等，都已被用來研究、發展及預測有關心搏停止的治療方法及效果。但這些傳統的心搏停止動物模型存在著低再現性以及實驗門檻較高的缺點。近年來斑馬魚 (Danio rerio) 漸漸成為常用的心血管疾病動物模型因為牠們擁有高繁殖率、與人類相似的基因以及在幼魚時期半透明的身體以便利用光學儀器觀察來心臟功能及心臟外觀。在此本論文中，我們利用缺氧再復氧的方法來建立斑馬魚心搏停止模型。我們先利用缺氧環境使斑馬魚的心搏停止再恢覆環境中的氧氣濃度來達到心肺復甦術的效果以恢復自主血液循環。在過程中我們發現受精後八天大的幼魚較年輕的幼魚相較於較年輕的幼魚較適合用來作為心搏停止的動物模型。我們在我們的斑馬魚心搏停止模型中觀察到了後心搏停止綜合症的特徵，包括：在心臟區域氧化壓力的上升、心肌細胞死亡、還有在恢復自主血液循環後心功能逐漸下降成心功能障礙甚至是回到心搏停止的過程。我們相信利用此動物模型不只可以幫助跟心搏停止有關的疾病的基礎研究還可以針對這些疾病來研發新的治療策略。

Cardiac arrest (CA) remains a critical challenge of public health. Almost 50% of all cardiovascular deaths is contributed by CA, which is mainly caused by and myocardial ischemia as a result of coronary stenosis or occlusion. Among the victims who are successfully rescued from CA to returning of spontaneous circulation (ROSC), only 5 to 10% of them would survive mainly because of complex pathophysiological processes that occur during ischemia and the subsequent reperfusion after ROSC (generally termed post cardiac arrest syndrome). A variety of animals have been developed as a model of cardiac arrest and these model systems have provided a useful platform for translational research and development of therapeutic intervention. However, they still suffer from limitations such as unsatisfactory reproducibility or complicated procedures of surgery. Recently, the zebrafish has become a popular model for cardiac research because of its high reproductive rate, high degree of genetic and functional conservation relative to human beings, and translucent body at larvae stage that facilitates dynamic observation of cardiac morphology and function in vivo. In this research, we report a novel zebrafish model of CA using hypoxia treatment to induce CA, and reoxygenation treatment to mimic the effect of CPR. By using pseudodynamic three-dimensional imaging, we particularly determined the cardiac function of zebrafish at varied phases post reoxygenation. We discovered that zebrafish larvae at 8 days post fertilization is suitable to model hypoxia induced cardiac arrest and ROSC after reoxygenation. More importantly, our observations conformed to some essential features of post cardiac arrest syndrome in higher animals, including an increased oxidative stress in the zebrafish heart, an increased myocardial cell death, and the dynamic change of cardiac function (dysfunction and resumption) after the onset of reoxygenation. We expect that our approach will benefit not only the fundamental research on diseases related to CA but also the investigation of new therapeutic strategies targeting these diseases.