Modeling of Heart Failure in Zebrafish
Heart failure is a silent yet deadly disease that has steadily risen this past decade due to the increase in the aging population. An alarming trend of heart failure in the young population has also been observed. To study this disease and find treatments or drugs for it, it is necessary to create a pre-clinical model. We describe the methods of creating a zebrafish model in heart failure along with its testing parameters.
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What is Heart Failure?
Heart failure is characterized by gradual deterioration of cardiac function, culminating in erratic heart rhythm and edema and eventually death. Most heart failures are chronic processes and commonly result from long-term hypertension or cardiovascular diseases. Weakening heart function often causes congestion, or fluid buildup in the lungs and other tissues, by hindering the flow of blood through the chambers of the heart. As a reflex response, several physiological systems, including the neurohormone, antidiuresis, and renin–angiotensin system, are triggered upon stress to the heart’s normal function to compensate for the insufficient cardiac output.
Why Zebrafish can be an effective animal model for heart failure?
- Zebrafish embryos have shown many advantages for human disease studies and drug discovery. A model at low cost which can be easily observed, and is possible to conduct rapid experimental procedures was created for zebrafish using zebrafish embryos and aristolochic acid (AA)
- Zebrafish models for heart diseases can be developed with the following phenotypes cardiac hypertrophy, severed cardiac fibers, loss of endocardium, and gradual weakening and subsequent cessation of cardiac contractility within 2 days of treatment.
Mode of Induction in Zebrafish:
- Cardiac phenotypes can appear as early as the embryonic stage at 48 hpf.
- These changes include distortion of the heart shape and decrease of heart size and gradual decrease of heart rate,
- Zebrafish at 48 hpf(hours post fertilization) is chosen to start verapamil treatment for the heart failure model development
Parameters to analyze heart development using quantitative and qualitative assays:
1) Quantitative image analysis
- Image-based morphometric analysis was performed under a microscope.
- Heart dilatation and venous congestion are mainly observed.
2) Quantitative Polymerase Chain Reaction
- 20 embryos from each treatment were subjected to RNA extraction with Trizol.
- Data were analyzed with the MxPro QPCR software to calculate the mRNA quantity of the genes of interest using the b-actin gene as a normalizer.
- Results of experimental groups were then compared with a control group (DMSO or AA-treated embryos
- A rapid in vivo screening and efficacy assessment of heart failure therapeutic drugs can be effectively done in zebrafish.
- Zebrafish is emerging as a predictive animal model for in vivo assessment of drug efficacy, toxicity, and safety.
- Zebrafish has morphological and molecular bases of tissues and organs that are either identical or similar to other vertebrates, including humans.