Studying Cardiovascular Mechanobiology in Development and Disease with Zebrafish

Zebrafish is a practical vertebrate model to investigate human cardiovascular disorders due to several advantages such as close genetic resemblance, cardiac physiological similarities, low maintenance costs, high throughput screening, and transparent body at early stages ideal for microscopy. In such investigations, cardiac function and blood flow hemodynamics should be assessed in a precise manner, in order to evaluate the influence of the interference on the cardiovascular system, which might then influence functioning and growth of other organ systems in the animal. For hemodynamic evaluation, important parameters include heart beat, stroke volume and cardiac output whereas some other parameters are fractional area change, fractional shortening, and vascular blood flow velocities. These analysis can be carried out by analyzing the animal under an inverted or a stereo brightfield microscope, most appropriate at the embryonic stage. Fluorescent labeling of myocardial walls, heart valves and red blood cells facilitates cardiac tissue and blood flow tracking respectively. From recorded high speed microscopy videos, atrial and ventricular dimensions as well as flow velocities are extracted to measure above mentioned parameters. This can be achieved manually or by using automated software applications. For adult zebrafish, doppler echocardiography is a useful and practical approach to assess cardiac function. In this case, doppler probe should be oriented aligned with the blood flow for the desired measurements (at atrioventricular canal, or outflow tract for example). In this presentation, we will summarize our experience on cardiac function analysis using high speed video microscopy and doppler echocardiography techniques on zebrafish. We will explain manual and automated video analysis to calculate cardiac parameters in zebrafish by providing results for different disease investigations from our lab.